Yields for J/psi production in Cu+Cu collisions at sqrt (s_NN)= 200 GeV have been measured by the PHENIX experiment over the rapidity range |y| < 2.2 at transverse momenta from 0 to beyond 5 GeV/c. The invariant yield is obtained as a function of rapidity, transverse momentum and collision centrality, and compared with results in p+p and Au+Au collisions at the same energy. The Cu+Cu data provide greatly improved precision over existing Au+Au data for J/psi production in collisions with small to intermediate numbers of participants, providing a key constraint that is needed for disentangling cold and hot nuclear matter effects.
J/PSI yield versus transverse momentum PT, at mid rapidity : -0.35<y<0.35, for a centrality range of 0-20%.
J/psi-->e+e- invariant yield in Cu+Cu collisions as a function of p_T at mid-rapidity for the 0-20 centrality range. The statistical and systematic uncertainties vary point-to-point and are listed for each measured value. An additional global systematic uncertainty is provided in each column heading, which applies to all data points per column.
J/PSI yield versus transverse momentum PT, at mid rapidity : -0.35<y<0.35, for a centrality range of 20-40%.
Muon production at forward rapidity (1.5 < |\eta| < 1.8) has been measured by the PHENIX experiment over the transverse momentum range 1 < p_T \le 3 GeV/c in sqrt(s) = 200 GeV p+p collisions at the Relativistic Heavy Ion Collider. After statistically subtracting contributions from light hadron decays an excess remains which is attributed to the semileptonic decays of hadrons carrying heavy flavor, i.e. charm quarks or, at high p_T, bottom quarks. The resulting muon spectrum from heavy flavor decays is compared to PYTHIA and a next-to-leading order perturbative QCD calculation. PYTHIA is used to determine the charm quark spectrum that would produce the observed muon excess. The corresponding differential cross section for charm quark production at forward rapidity is determined to be d\sigmac c^bar)/dy|_(y=1.6)=0.243 +/- 0.013 (stat.) +/- 0.105 (data syst.) ^(+0.049(-0.087) (PYTHIA syst.) mb.
Differential charm cross section at forward rapidity of 1.6 An additional +0.049 -0.087 systematic uncertainty associated with the PYTHIA normalization is not included in the values given.
The PHENIX experiment at the Relativistic Heavy Ion Collider has measured low mass vector meson, $\omega$, $\rho$, and $\phi$, production through the dimuon decay channel at forward rapidity ($1.2<|y|<2.2$) in $p$$+$$p$ collisions at $\sqrt{s}=200$ GeV. The differential cross sections for these mesons are measured as a function of both $p_T$ and rapidity. We also report the integrated differential cross sections over $1<p_T<7$ GeV/$c$ and $1.2<|y|<2.2$: $d\sigma/dy(\omega+\rho\rightarrow\mu\mu) = 80 \pm 6 \mbox{(stat)} \pm 12 \mbox{(syst)}$ nb and $d\sigma/dy(\phi\rightarrow\mu\mu) = 27 \pm 3 \mbox{(stat)} \pm 4 \mbox{(syst)}$ nb. These results are compared with midrapidity measurements and calculations.
Differential cross sections of (OMEGA + RHO) and PHI as functions of PT. The statistical uncertainty includes the type-A systematic uncertainty. The systematic uncertainty is the type-B systematic uncertainty.
Differential cross sections of (OMEGA + RHO) and PHI as functions of rapidity. The statistical uncertainty includes the type-A systematic uncertainty. The systematic uncertainty is the type-B systematic uncertainty.
N(PHI) / ( N(OMEGA) + N(RHO) ) as a function of PT. The statistical uncertainty includes the type-A systematic uncertainty. The systematic uncertainty is the type-B systematic uncertainty.
J/Psi production in p+p collisions at sqrt(s) = 200 GeV has been Measured in the PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC) over a rapidity range of -2.2 < y < 2.2 and a transverse momentum range of 0 < pT < 9 GeV/c. The statistics available allow a detailed measurement of both the pT and rapidity distributions and are sufficient to constrain production models. The total cross section times branching ratio determined for J/Psi production is B_{ll} sigma_pp^J/psi = 178 +/- 3(stat) +/- 53(syst) +/- 18(norm) nb.
J/PSI differential cross section, times dilepton branching ratio, versus transverse momentum PT, at mid rapidity : -0.35<y<0.35.
J/PSI differential cross section, times dilepton branching ratio, versus transverse momentum PT, at forward rapidities : absolute value of y belongs to [1.2;2.2].
Mean PT^2 value at mid rapidities : -0.35<y<0.35 The mean PT is obtained with a phenomonological fit of the J/PSI distribution in PT of the form (1/(2*PI*PT))*D(SIG)/DPT = A ( 1+(PT/B)^2)^-6 .The systematic error includes the incertainty from the maximum shape deviation permitted by the point-to-point correlated errors and from allowing the exponent of the fit fonctionto be a free parameter.
All of the experimental data points presented in the original paper are correct and unchanged (including statistical and systematic uncertainties). However, herein we correct a comparison between the experimental data and a theoretical picture, because we discovered a mistake in the code used. All of the most probable sigma_breakup values differ by less than 0.4 mb from those originally presented. However, the one standard deviation uncertainties (that include contributions from both the statistical and systematic uncertainties on the experimental data points) are approximately 30-60% larger than originally reported. We give a table of the new comparison results and corrected versions of Figs. 8-11 of the original paper and we note that no correction is needed for results from the data-driven method in Fig. 13.
J/PSI invariant (1/(2PI*PT))*D2(N)/DPT/DYRAP versus rapidity in D+AU collisions, over 3 bins of rapidity.
J/PSI invariant (1/(2PI*PT))*D2(N)/DPT/DYRAP versus rapidity in D+AU collisions, over 5 bins of rapidity.
J/PSI invariant (1/(2PI*PT))*D2(N)/DPT/DYRAP versus PT at backward rapidity (-2.2<y<-1.2) in D+AU collisions.
The PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC) has measured J/psi production for rapidities 2.2 < y < 2.2 in Au+Au collisions at sqrt(s_NN) = 200 GeV. The J/psi invariant yield and nuclear modification factor R_AA as a function of centrality, transverse momentum and rapidity are reported. A suppression of J/psi relative to binary collision scaling of proton-proton reaction yields is observed. Models which describe the lower energy J/Psi data at the Super Proton Synchrotron (SPS) invoking only J/psi destruction based on the local medium density would predict a significantly larger suppression at RHIC and more suppression at mid rapidity than at forward rapidity. Both trends are contradicted by our data.
J/PSI invariant yield versus transverse momentum for 0-20%, 20-40%, 40-60%, 60-92% centrality at mid rapidity :,-0.35<y<0.35 An up/down correction, to translate each point at the center of it's relative bin, have been applied to the data.
J/PSI invariant yield versus transverse momentum for 0-20%, 20-40%, 40-60%, 60-92% centrality at forward rapidities : absolute value of y belongs to [1.2;2.2] An up/down correction, to translate each point at the center of it's relative bin, have been applied to the data.
Mean PT^2 values for different bins of centrality, at mid rapidities :-0.35<y<0.35,.
J/psi production in d+Au and p+p collisions at sqrt(s_NN) = 200 GeV has been measured by the PHENIX experiment at rapidities -2.2 < y < +2.4. The cross sections and nuclear dependence of J/\psi production versus rapidity, transverse momentum, and centrality are obtained and compared to lower energy p+A results and to theoretical models. The observed nuclear dependence in d+Au collisions is found to be modest, suggesting that the absorption in the final state is weak and the shadowing of the gluon distributions is small and consistent with Dokshitzer-Gribov-Lipatov-Altarelli-Parisi-based parameterizations that fit deep-inelastic scattering and Drell-Yan data at lower energies.
J/PSI differential cross section in P+P reactions( times di-lepton branching ratio B=5.9%) as a function of rapidity.
J/PSI nuclear modification factor RDA,as a function of rapidity.
Total cross-section for J/PSI production in P P reactions. The total cross section is estimated using a pythia calculation, normalized to our data. The di-lepton branching ratio used is 5.9%.The systematic error given is due to the fit. The choice of the PDF and model was estimated to have little impact in the value of the total cross section.
J/psi production has been measured in proton-proton collisions at sqrt(s)= 200 GeV over a wide rapidity and transverse momentum range by the PHENIX experiment at RHIC. Distributions of the rapidity and transverse momentum, along with measurements of the mean transverse momentum and total production cross section are presented and compared to available theoretical calculations. The total J/psi cross section is 3.99 +/- 0.61(stat) +/- 0.58(sys) +/- 0.40(abs) micro barns. The mean transverse momentum is 1.80 +/- 0.23(stat) +/- 0.16(sys) GeV/c.
Measured J/PSI distribution in PT for the e+e- channel. The value of B, the branching fraction to either electrons or muons is the average value from PDG : 5.9%.The rapidity range is -0.35<y<0.35. Incertainties are 1-sigma statistical errors on the (signal - background) net yield. There is a 10% overall absolute cross section normalization error in addition to the error given.
Measured J/PSI distribution in PT for the mu+mu- channel. The value of B, the branching fraction to either electrons or muons, is the average value from PDG: 5.9%.The rapidity range is -2.2<y<-1.2. Incertainties are 1-sigma statistical errors on the (signal - background) net yield.There is a 10% overall absolute cross section normalization error in addition to the error given.
J/PSI distribution in rapidity. The data at rapidity = 0 is from the electron arm, the data from the muon arm, corresponding to forward rapidity is divided in two bins.The value of B,the branching fraction to either electrons or muons, is 5.9%, the average value from PDG.Incertainties are 1-sigma statistical errors on the (signal - background) net yield.There is a 10% overall absolute cross section normalization error in addition to the error given.
A search for the lepton flavor violating $\tau$$\to$ 3$\mu$ decay is performed using proton-proton collision events at a center-of-mass energy of 13 TeV collected by the CMS experiment at the LHC in 2017-2018, corresponding to an integrated luminosity of 97.7 fb$^{-1}$. Tau leptons produced in both heavy-flavor hadron and W boson decays are exploited in the analysis. No evidence for the decay is observed. The results of this search are combined with an earlier null result based on data collected in 2016 to obtain a total integrated luminosity of 131 fb$^{-1}$. The observed (expected) upper limits on the branching fraction $\mathcal{B}$($\tau$$\to$ 3$\mu$) at confidence levels of 90 and 95% are 2.9 $\times$ 10$^{-8}$ (2.4 $\times$ 10$^{-8}$) and 3.6 $\times$ 10$^{-8}$ (3.0 $\times$ 10$^{-8}$), respectively.
Expected and observed upper limits on the $\tau\to3\mu$ branching fraction at 90% of confidence level for different categories of the analyis.
Expected and observed upper limits on the $\tau\to3\mu$ branching fraction at 95% of confidence level for the Run2 combination.
We present a measurement of inclusive J/$\psi$ production in p-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV as a function of the centrality of the collision, as estimated from the energy deposited in the Zero Degree Calorimeters. The measurement is performed with the ALICE detector down to zero transverse momentum, $p_{\rm T}$, in the backward ($-4.46 < y_{\rm cms} < -2.96$) and forward ($2.03 < y_{\rm cms} < 3.53$) rapidity intervals in the dimuon decay channel and in the mid-rapidity region ($-1.37 < y_{\rm cms} < 0.43$) in the dielectron decay channel. The backward and forward rapidity intervals correspond to the Pb-going and p-going direction, respectively. The $p_{\rm T}$-differential J/$\psi$ production cross section at backward and forward rapidity is measured for several centrality classes, together with the corresponding average $p_{\rm T}$ and $p^2_{\rm T}$ values. The nuclear modification factor, $Q_{\rm pPb}$, is presented as a function of centrality for the three rapidity intervals, and, additionally, at backward and forward rapidity, as a function of $p_{\rm T}$ for several centrality classes. At mid- and forward rapidity, the J/$\psi$ yield is suppressed up to 40% compared to that in pp interactions scaled by the number of binary collisions. The degree of suppression increases towards central p-Pb collisions at forward rapidity, and with decreasing $p_{\rm T}$ of the J/$\psi$. At backward rapidity, the $Q_{\rm pPb}$ is compatible with unity within the total uncertainties, with an increasing trend from peripheral to central p-Pb collisions.
Differential cross sections dsigma_JPsi/dydpt as function of pt at backward (-4.46<y_cms<-2.96) centre-of-mass rapidity. The first uncertainty is statistical, the second and third ones are the systematic uncertainties. The third uncertainty is fully correlated over pT.
Differential cross sections d^2sigma^cent_JPsi/dydpt as function of pt for six centrality classes at forward (2.03<y_cms<3.53) centre-of-mass rapidity. The first uncertainty is statistical, the second and third ones are the systematic uncertainties. The third uncertainty is fully correlated over pT.
Differential cross sections dsigma^cent_JPsi/dy for four centrality classes at mid-rapidity (-1.37<y_cms<0.43). The first uncertainty is statistical, the second and third ones are the systematic uncertainties. The third uncertainty is fully correlated over centrality.
The inclusive production cross sections at forward rapidity of J/$\psi$, $\psi$(2S), $\Upsilon$(1S) and $\Upsilon$(2S) are measured in pp collisions at $\sqrt{s} = 7$ TeV with the ALICE detector at the LHC. The analysis is based in a data sample corresponding to an integrated luminosity of 1.35 pb$^{-1}$. Quarkonia are reconstructed in the dimuon-decay channel and the signal yields are evaluated by fitting the $\mu^+\mu^-$ invariant mass distributions. The differential production cross sections are measured as a function of the transverse momentum $p_{\rm T}$ and rapidity $y$, over the ranges $0 < p_{\rm T} < 20$ GeV/$c$ for J/$\psi$, $0 < p_{\rm T} < 12$ GeV/$c$ for all other resonances and for $2.5 < y < 4$. The measured cross sections integrated over $p_{\rm T}$ and $y$, and assuming unpolarized quarkonia, are: $\sigma_{J/\psi} = 6.69 \pm 0.04 \pm 0.63$ $\mu$b, $\sigma_{\psi^{\prime}} = 1.13 \pm 0.07 \pm 0.14$ $\mu$b, $\sigma_{\Upsilon{\rm(1S)}} = 54.2 \pm 5.0 \pm 6.7$ nb and $\sigma_{\Upsilon{\rm (2S)}} = 18.4 \pm 3.7 \pm 2.2$ nb, where the first uncertainty is statistical and the second one is systematic. The results are compared to measurements performed by other LHC experiments and to theoretical models.
Differential production cross sections of J/psi as a function of pT.
Differential production cross sections of J/psi as a function of rapidity.
integrated production cross section of J/psi.
The ALICE Collaboration has studied the inclusive production of the charmonium state $\psi(2S)$ in proton-lead (p-Pb) collisions at the nucleon-nucleon centre of mass energy $\sqrt{s_{NN}}$ = 5.02 TeV at the CERN LHC. The measurement was performed at forward ($2.03<y_{cms}<3.53$) and backward ($-4.46<y_{cms}<-2.96$) centre of mass rapidities, studying the decays into muon pairs. In this paper, we present the inclusive production cross sections $\sigma_{\psi(2S)}$, both integrated and as a function of the transverse momentum $p_{T}$, for the two $y_{cms}$ domains. The results are compared to those obtained for the 1S vector state (J/$\psi$), by showing the ratios between the production cross sections, as well as the double ratios $[\sigma_{\psi(2S)}/\sigma_{J/\psi}]_{pPb}/[\sigma_{\psi(2S)}/\sigma_{J/\psi}]_{pp}$ between p-Pb and proton-proton collisions. Finally, the nuclear modification factor for inclusive $\psi(2S)$ is evaluated and compared to the measurement of the same quantity for J/$\psi$ and to theoretical models including parton shadowing and coherent energy loss mechanisms. The results show a significantly larger suppression of the $\psi(2S)$ compared to that measured for J/$\psi$ and to models. These observations represent a clear indication for sizeable final state effects on $\psi(2S)$ production.
The cross section ratios B.R. sigma_Psi(2S)/ B.R. sigma_JPsi obtained in p-Pb and Pb-p collisions. The first uncertainty is statistical, the second one is systematic.
The double ratio [sigma(Psi(2S))/sigma(J/Psi)]_pA/[sigma(Psi(2S))/sigma(J/Psi)]_pp for p-Pb and Pb-p collisions. First uncertainty is statistical, the second one is the correlated systematic, while the third is the uncorrelated systematic.
The Psi(2S) nuclear modification factor RpA measured in pPb and Pbp collisions. The first uncertainty is statistical, the second one is the correlated systematic and the third the uncorrelated systematic.
We present the first measurement at the LHC of exclusive J/$\psi$ photoproduction off protons, in ultra-peripheral proton-lead collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV. Events are selected with a dimuon pair produced either in the rapidity interval, in the laboratory frame, $2.5<y<4$ (p-Pb) or $-3.6<y<-2.6$ (Pb--p), and no other particles observed in the ALICE acceptance. The measured cross sections $\sigma (\gamma + {\rm p} \rightarrow J/\psi + {\rm p})$ are 33.2 $\pm$ 2.2 (stat) $\pm$ 3.1 (syst) $\pm$ 0.7 (theo) nb in p-Pb and 284 $\pm$ 36 (stat) $^{+27}_{-32}$ (syst) $\pm$ 26 (theo) nb in Pb-p collisions. We measure this process up to about 700 GeV in the $\gamma {\rm p}$ centre-of-mass, which is a factor of two larger than the highest energy studied at HERA. The data are consistent with a power law dependence of the $J/\psi$ photoproduction cross section in $\gamma {\rm p}$ energies from about 20 to 700 GeV, or equivalently, from Bjorken-$x$ between $\sim 2\times 10^{-2}$ to $\sim 2\times 10^{-5}$, thus indicating no significant change in the gluon density behaviour of the proton between HERA and LHC energies.
Differential cross sections as a function of rapidity for exclusive J/PSI photoproduction off protons in ultra-peripheral p-Pb collisions. The corresponding J/PSI photoproduction cross sections in bins of the GAMMA-P centre-of-mass, W(GAMMA P), are also presented.
Differential cross section as a function of rapidity for exclusive J/PSI photoproduction off protons in ultra-peripheral Pb-p collisions. The corresponding J/PSI photoproduction cross section in a range of the GAMMA-P centre-of-mass, W(GAMMA P), is also presented.
We report on the inclusive production cross sections of J/$\psi$, $\psi$(2S), $\Upsilon$(1S), $\Upsilon$(2S) and $\Upsilon$(3S), measured at forward rapidity with the ALICE detector in pp collisions at a center-of-mass energy $\sqrt{s}=8$ TeV. The analysis is based on data collected at the LHC and corresponds to an integrated luminosity of 1.28 pb$^{-1}$. Quarkonia are reconstructed in the dimuon-decay channel. The differential production cross sections are measured as a function of the transverse momentum $p_{\rm T}$ and rapidity $y$, over the $p_{\rm T}$ ranges $0<p_{\rm T}<20$ GeV/$c$ for J/$\psi$, $0<p_{\rm T}<12$ GeV/$c$ for all other resonances, and for $2.5<y<4$. The cross sections, integrated over $p_{\rm T}$ and $y$, and assuming unpolarized quarkonia, are $\sigma_{{\rm J}/\psi} = 8.98\pm0.04\pm0.82$ $\mu$b, $\sigma_{\psi{\rm (2S)}} = 1.23\pm0.08\pm0.22$ $\mu$b, $\sigma_{\Upsilon{\rm(1S)}} = 71\pm6\pm7$ nb, $\sigma_{\Upsilon{\rm(2S)}} = 26\pm5\pm4$ nb and $\sigma_{\Upsilon{\rm(3S)}} = 9\pm4\pm1$ nb, where the first uncertainty is statistical and the second one is systematic. These values agree, within at most $1.4\sigma$, with measurements performed by the LHCb collaboration in the same rapidity range.
Differential production cross sections of J/$\psi$ as a function of $p_{\rm T}$.
Differential production cross sections of J/$\psi$ as a function of rapidity.
integrated production cross section of J/$\psi$.
We have studied the transverse-momentum ($p_{\rm T}$) dependence of the inclusive J/$\psi$ production in p-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV, in three center-of-mass rapidity ($y_{\rm cms}$) regions, down to zero $p_{\rm T}$. Results in the forward and backward rapidity ranges ($2.03 < y_{\rm cms} < 3.53$ and $-4.46 <y_{\rm cms}< -2.96$) are obtained by studying the J/$\psi$ decay to $\mu^+\mu^-$, while the mid-rapidity region ($-1.37 < y_{\rm cms} < 0.43$) is investigated by measuring the ${\rm e}^+{\rm e}^-$ decay channel. The $p_{\rm T}$ dependence of the J/$\psi$ production cross section and nuclear modification factor are presented for each of the rapidity intervals, as well as the J/$\psi$ mean $p_{\rm T}$ values. Forward and mid-rapidity results show a suppression of the J/$\psi$ yield, with respect to pp collisions, which decreases with increasing $p_{\rm T}$. At backward rapidity no significant J/$\psi$ suppression is observed. Theoretical models including a combination of cold nuclear matter effects such as shadowing and partonic energy loss, are in fair agreement with the data, except at forward rapidity and low transverse momentum. The implications of the p-Pb results for the evaluation of cold nuclear matter effects on J/$\psi$ production in Pb-Pb collisions are also discussed.
$p_{\rm T}$-differential inclusive cross section ${\rm d}^2\sigma^{J/\psi}/{\rm d}y{\rm d}p_{T}$ in the backward rapidity range (-4.46<$y_{\rm cms}$<-2.96). The first uncertainty is statistical, the second one is the $p_{\rm T}$-uncorrelated systematic uncertainty, while the third is the $p_{\rm T}$-correlated one.
$p_{\rm T}$-differential inclusive cross section ${\rm d}^2\sigma^{J/\psi}/{\rm d}y{\rm d}p_{T}$ in the mid-rapidity range (-1.37<$y_{\rm cms}$<0.43). The first uncertainty is statistical, the second one is the $p_{\rm T}$-uncorrelated systematic uncertainty, while the third is the $p_{\rm T}$-correlated one.
$p_{\rm T}$-differential inclusive cross section ${\rm d}^2\sigma^{J/\psi}/{\rm d}y{\rm d}p_{T}$ in the forward rapidity range (2.03<$y_{\rm cms}$<3.53). The first uncertainty is statistical, the second one is the $p_{\rm T}$-uncorrelated systematic uncertainty, while the third is the $p_{\rm T}$-correlated one.
Inclusive J/$\psi$ production has been studied with the ALICE detector in p-Pb collisions at the nucleon-nucleon center of mass energy $\sqrt{s_{\rm NN}}$ = 5.02 TeV at the CERN LHC. The measurement is performed in the center of mass rapidity domains $2.03<y_{\rm cms}<3.53$ and $-4.46<y_{\rm cms}<-2.96$, down to zero transverse momentum, studying the $\mu^+\mu^-$ decay mode. In this paper, the J/$\psi$ production cross section and the nuclear modification factor $R_{\rm pPb}$ for the rapidities under study are presented. While at forward rapidity, corresponding to the proton direction, a suppression of the J/$\psi$ yield with respect to binary-scaled pp collisions is observed, in the backward region no suppression is present. The ratio of the forward and backward yields is also measured differentially in rapidity and transverse momentum. Theoretical predictions based on nuclear shadowing, as well as on models including, in addition, a contribution from partonic energy loss, are in fair agreement with the experimental results.
The inclusive JPsi nuclear modification factor obtained in p-Pb and Pb-p collisions. The first uncertainty is statistical, the second one is the uncorrelated systematic uncertainty, while the third one is the partially correlated systematic uncertainty. The fourth is a global uncertainty common to p-Pb and Pb-p results.
The rapidity dependence of the inclusive JPsi production cross-section obtained in p-Pb and Pb-p collisions. The first uncertainty is statistical, the second one is the uncorrelated systematic uncertainty, while the third one is the partially correlated systematic uncertainty.
The rapidity dependence of the inclusive JPsi nuclear modification factor obtained in p-Pb and Pb-p collisions. The first uncertainty is statistical, the second one is the uncorrelated systematic uncertainty, while the third one is the partially correlated systematic uncertainty. The fourth is a global uncertainty common to p-Pb and Pb-p results.
The elliptic flow, $v_{2}$, of muons from heavy-flavour hadron decays at forward rapidity ($2.5 < y < 4$) is measured in Pb--Pb collisions at $\sqrt{s_{\rm NN}}$~=~2.76 TeV with the ALICE detector at the LHC. The scalar product, two- and four-particle $Q$ cumulants and Lee-Yang zeros methods are used. The dependence of the $v_2$ of muons from heavy-flavour hadron decays on the collision centrality, in the range 0--40\%, and on transverse momentum, $p_{\rm T}$, is studied in the interval $3 < p_{\rm T} < 10$~GeV/$c$. A positive $v_2$ is observed with the scalar product and two-particle $Q$ cumulants in semi-central collisions (10--20\% and 20--40\% centrality classes) for the $p_{\rm T}$ interval from 3 to about 5 GeV/$c$. The $v_2$ magnitude tends to decrease towards more central collisions and with increasing $p_{\rm T}$. It becomes compatible with zero in the interval $6<p_{\rm T}<10~{\rm GeV/}c$. The results are compared to models describing the interaction of heavy quarks and open heavy-flavour hadrons with the high-density medium formed in high-energy heavy-ion collisions. The model calculations describe the measured $v_2$ within uncertainties.
pT-differential inclusive muon $v_{2}$ extracted with scalar product method.
pT-differential inclusive muon $v_{2}$ extracted with two-particle $Q$ cumulants method.
pT-differential inclusive muon $v_{2}$ extracted with scalar product method.
The ALICE Collaboration has measured the energy dependence of exclusive photoproduction of $J/\psi$ vector mesons off proton targets in ultra-peripheral p-Pb collisions at a centre-of-mass energy per nucleon pair $\sqrt{s_{\rm NN}} = 5.02$ TeV. The e$^+$e$^-$ and $\mu^+\mu^-$ decay channels are used to measure the cross section as a function of the rapidity of the $J/\psi$ in the range $-2.5 < y < 2.7$, corresponding to an energy in the $\gamma$p centre-of-mass in the interval $40 < W_{\gamma\mathrm{p}}<550$ GeV. The measurements, which are consistent with a power law dependence of the exclusive $J/\psi$ photoproduction cross section, are compared to previous results from HERA and the LHC and to several theoretical models. They are found to be compatible with previous measurements.
Differential cross sections as a function of rapidity for exclusive J/PSI photoproduction off protons in ultra-peripheral p-Pb collisions. The corresponding J/PSI photoproduction cross sections in bins of the GAMMA-P centre-of-mass, W(GAMMA P), are also presented.
Protons consist of three valence quarks, two up-quarks and one down-quark, held together by gluons and a sea of quark-antiquark pairs. Collectively, quarks and gluons are referred to as partons. In a proton-proton collision, typically only one parton of each proton undergoes a hard scattering - referred to as single-parton scattering - leaving the remainder of each proton only slightly disturbed. Here, we report the study of double- and triple-parton scatterings through the simultaneous production of three J/$\psi$ mesons, which consist of a charm quark-antiquark pair, in proton-proton collisions recorded with the CMS experiment at the Large Hadron Collider. We observed this process - reconstructed through the decays of J/$\psi$ mesons into pairs of oppositely charged muons - with a statistical significance above five standard deviations. We measured the inclusive fiducial cross section to be 272 $^{+141}_{-104}$ (stat) $\pm$ 17 (syst) fb, and compared it to theoretical expectations for triple-J/$\psi$ meson production in single-, double- and triple-parton scattering scenarios. Assuming factorization of multiple hard-scattering probabilities in terms of single-parton scattering cross sections, double- and triple-parton scattering are the dominant contributions for the measured process.
Kinematic properties of each one of the three \JPsi mesons selected in the 5? 6? signal events.
Dimuon invariant mass ($m$), proper decay-length ($L$), transverse momentum ($p_{T}$), rapidity ($y$), and azimuthal angle ($\phi$) of each of the three $J/\psi$ candidates measured in the six triple-$J/\psi$ events passing our selection criteria.
DPS effective cross section
The production of a Z boson, decaying into two leptons and produced in association with one or more b jets, is studied using proton-proton collisions delivered by the LHC at a centre-of-mass energy of 7 TeV. The data were recorded in 2011 with the CMS detector and correspond to an integrated luminosity of 5 inverse femtobarns. The Z(ll) + b-jets cross sections (where ll = mu mu or ee) are measured separately for a Z boson produced with exactly one b jet and with at least two b jets. In addition, a cross section ratio is extracted for a Z boson produced with at least one b jet, relative to a Z boson produced with at least one jet. The measured cross sections are compared to various theoretical predictions, and the data favour the predictions in the five-flavour scheme, where b quarks are assumed massless. The kinematic properties of the reconstructed particles are compared with the predictions from the MADGRAPH event generator using the PYTHIA parton shower simulation.
The cross section at the particle level for the production of a Z boson with exactly one b-jet.
The cross section at the particle level for the production of a Z boson with at least two b-jets.
The cross section at the particle level for the production of a Z boson with at least one b-jet.
Differential cross sections as a function of transverse momentum pt are presented for the production of Y(nS) (n = 1, 2, 3) states decaying into a pair of muons. Data corresponding to an integrated luminosity of 4.9 inverse femtobarns in pp collisions at sqrt(s) = 7 TeV were collected with the CMS detector at the LHC. The analysis selects events with dimuon rapidity abs(y) < 1.2 and dimuon transverse momentum in the range 10 < pt < 100 GeV. The measurements show a transition from an exponential to a power-law behavior at pt ~ 20 GeV for the three Y states. Above that transition, the Y spectrum is significantly harder than that of the Y(1S) and Y(2S). The ratios of the Y(3S) and Y(2S) differential cross sections to the Y(1S) cross section show a rise as pt increases at low pt, then become flatter at higher pt.
The $p_{\rm T}$ bin width, the weighted mean $p_{\rm T}$ within a bin, and the differential cross section times the dimuon branching fraction for the $\Upsilon$(1S), $\Upsilon$(2S), and $\Upsilon$(3S) with $0 < |y| < 0.6$. The statistical and systematic uncertainties in the differential cross section are given as the percentage of the cross section.
The $p_{\rm T}$ bin width, the weighted mean $p_{\rm T}$ within a bin, and the differential cross section times the dimuon branching fraction for the $\Upsilon$(1S), $\Upsilon$(2S), and $\Upsilon$(3S) with $0.6 < |y| < 1.2$. The statistical and systematic uncertainties in the differential cross section are given as the percentage of the cross section.
The $p_{\rm T}$ bin width, the weighted mean $p_{\rm T}$ within a bin, and the differential cross section times the dimuon branching fraction for the $\Upsilon$(1S), $\Upsilon$(2S), and $\Upsilon$(3S) with $|y| < 1.2$. The statistical and systematic uncertainties in the differential cross section are given as the percentage of the cross section.
The ratio of the top-quark branching fractions $R = B(t \to Wb)/B(t \to Wq)$, where the denominator includes the sum over all down-type quarks (q = b, s, d), is measured in the $t\bar{t}$ dilepton final state with proton-proton collision data at $\sqrt{s}$ = 8 TeV from an integrated luminosity of 19.7 inverse-femtobarns, collected with the CMS detector. In order to quantify the purity of the signal sample, the cross section is measured by fitting the observed jet multiplicity, thereby constraining the signal and background contributions. By counting the number of b jets per event, an unconstrained value of R = 1.014 $\pm$ 0.003 (stat) $\pm$ 0.032 (syst) is measured, in good agreement with the standard model prediction. A lower limit R greater than 0.955 at the 95% confidence level is obtained after requiring R lower than one, and a lower limit on the Cabibbo-Kobayashi-Maskawa matrix element |$V_tb$| greater than 0.975 is set at 95% confidence level. The result is combined with a previous CMS measurement of the t-channel single-top-quark cross section to determine the top-quark total decay width, $\Gamma_t$ = 1.36 $\pm$ 0.02 (stat)$^{+0.14}_{-0.11}$ (syst) GeV.
The measured TOP TOPBAR production cross section.
The measured ratio of branching fractions, R = BR(TOP --> W BOTTOM) / BR(TOP --> W QUARK) where the denominator includes the sum over all down-type quarks (QUARK = BOTTOM, STRANGE, DOWN). The combined measurement and the individual measurements from the three channels considered are presented.
An indirect measurement of the top-quark total decay width.
The inclusive top quark pair ($t\bar{t}$) production cross-section $\sigma_{t\bar{t}}$ has been measured in $pp$ collisions at $\sqrt{s}=7$ TeV and $\sqrt{s}=8$ TeV with the ATLAS experiment at the LHC, using $t\bar{t}$ events with an opposite-charge $e\mu$ pair in the final state. The measurement was performed with the 2011 7 TeV dataset corresponding to an integrated luminosity of 4.6 fb$^{-1}$ and the 2012 8 TeV dataset of 20.3 fb$^{-1}$. The cross-section was measured to be: $\sigma_{t\bar{t}}=182.9\pm 3.1\pm 4.2\pm 3.6 \pm 3.3$ pb ($\sqrt{s}=7$ TeV) and $\sigma_{t\bar{t}}=242.9\pm 1.7\pm 5.5\pm 5.1\pm 4.2$ pb ($\sqrt{s}=8$ TeV, updated as described in the Addendum), where the four uncertainties arise from data statistics, experimental and theoretical systematic effects, the knowledge of the integrated luminosity and of the LHC beam energy. The results are consistent with recent theoretical QCD calculations at next-to-next-to-leading order. Fiducial measurements corresponding to the experimental acceptance of the leptons are also reported, together with the ratio of cross-sections measured at the two centre-of-mass energies. The inclusive cross-section results were used to determine the top quark pole mass via the dependence of the theoretically-predicted cross-section on $m_t^{\rm pole}$, giving a result of $m_t^{\rm pole}=172.9^{+2.5}_{-2.6}$ GeV. By looking for an excess of $t\bar{t}$ production with respect to the QCD prediction, the results were also used to place limits on the pair-production of supersymmetric top squarks $\tilde{t}_1$ with masses close to the top quark mass decaying via $\tilde{t}_1\rightarrow t\tilde{\chi}^0_1$ to predominantly right-handed top quarks and a light neutralino $\tilde{\chi}_0^1$, the lightest supersymmetric particle. Top squarks with masses between the top quark mass and 177 GeV are excluded at the 95% confidence level.
95% CL exclusion limit on signal strength.
95% CL exclusion limit on signal cross section for the 7 TeV dataset.
95% CL exclusion limit on signal cross section for the 8 TeV dataset.
A measurement of the forward-backward asymmetry (A[FB]) of Drell-Yan lepton pairs in pp collisions at sqrt(s) = 7 TeV is presented. The data sample, collected with the CMS detector, corresponds to an integrated luminosity of 5 inverse femtobarns. The asymmetry is measured as a function of dilepton mass and rapidity in the dielectron and dimuon channels. Combined results from the two channels are also presented. The A[FB] measurement in the dimuon channel and the combination of the two channels are the first such results obtained at a hadron collider. The measured asymmetries are consistent with the standard model predictions.
The unfolded mu+mu- measurement of AFB at the Born level in four rapidity bins. The errors on data are statistical only.
The unfolded e+e- measurement of AFB at the Born level in four rapidity bins. The errors on data are statistical only.
Unfolded combined measurements of AFB in each M-|y| bin (mu+mu- and e+e- combined).
Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pt) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 inverse femtobarns. The measured cross sections are compared to predictions from Monte Carlo generators, MADGRAPH + PYTHIA and SHERPA, and to next-to-leading-order calculations from BLACKHAT + SHERPA. The differential cross sections are found to be in agreement with the predictions, apart from the pt distributions of the leading jets at high pt values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.
The cross section measurement as a function of the exclusive jet multiplicity, for jet multiplicities of up to 6.
The cross section measurement as a function of the inclusive jet multiplicity, for jet multiplicities of up to 6.
The differential cross section measurement as a function of the transverse momentum of the first leading jet.
Measurements of four-lepton (4$\ell$, $\ell=e,\mu$) production cross sections at the $Z$ resonance in $pp$ collisions at the LHC with the ATLAS detector are presented. For dilepton and four-lepton invariant mass region $m_{\ell^+\ell^-} > 5$ GeV and $80 < m_{4\ell} < 100$ GeV, the measured cross sections are $76 \pm 18 \text { (stat) } \pm 4 \text { (syst) } \pm 1.4 \text { (lumi) }$ fb and $107 \pm 9 \text{ (stat) } \pm 4 \text{ (syst) } \pm 3.0 \text { (lumi) }$ fb at $\sqrt s$ = 7 and 8 TeV, respectively. By subtracting the non-resonant 4$\ell$ production contributions and normalizing with $Z\rightarrow \mu^+\mu^-$ events, the branching fraction for the $Z$ boson decay to $4\ell$ is determined to be $\left( 3.20 \pm 0.25\text{ (stat)} \pm 0.13\text{ (syst)} \right) \times 10^{-6}$, consistent with the Standard Model prediction.
The measured individual cross sections in the fiducial region and the combined cross sections for 4-muon and 4-electron final states at a centre-of-collision energy of 7 TeV.
The measured individual cross sections in the fiducial region and the combined cross sections for 2-muon-2-electron final states at a centre-of-collision energy of 7 TeV.
The measured cross section for four-lepton final states at a centre-of-collision energy of 7 TeV.
The cross section for the production of Z gamma in proton-proton collisions at 8 TeV is measured based on data collected by the CMS experiment at the LHC corresponding to an integrated luminosity of 19.5 inverse femtobarns. Events with an oppositely-charged pair of muons or electrons together with an isolated photon are selected. The differential cross section as a function of the photon transverse momentum is measured inclusively and exclusively, where the exclusive selection applies a veto on central jets. The observed cross sections are compatible with the expectations of next-to-next-to-leading-order quantum chromodynamics. Limits on anomalous triple gauge couplings of Z Z gamma and Z gamma gamma are set that improve on previous experimental results obtained with the charged lepton decay modes of the Z boson.
Inclusive fiducial cross sections in bins of pT(gamma) with statistical, systematic, and luminosity uncertainties, respectivley. Results are not divided by bin-widths. The last bin is the cross section for pT(gamma) > 120 GeV. Combined result of electron and muon channels.
Fiducial cross sections with jet-veto in bins of pT(gamma) with statistical, systematic, and luminosity uncertainties, respectivley. Results are not divided by bin-widths. The last bin is the cross section for pT(gamma) > 120 GeV. Combined result of electron and muon channels.
Ratio of fiducial cross section with jet-veto and the inclusive cross section in bins of pT(gamma). The last bin is the cross section for pT(gamma) > 120 GeV. Combined result of electron and muon channels.
The differential cross sections for the production of photons in Z to mu+ mu- gamma decays are presented as a function of the transverse energy of the photon and its separation from the nearest muon. The data for these measurements were collected with the CMS detector and correspond to an integrated luminosity of 4.7 inverse femtobarns of pp collisions at sqrt(s) = 7 TeV delivered by the CERN LHC. The cross sections are compared to simulations with POWHEG and PYTHIA, where PYTHIA is used to simulate parton showers and final-state photons. These simulations match the data to better than 5%.
Measured differential cross section dsigma/dET in pb/GeV. For the data values, the first uncertainty is statistical and the second is systematic. For the theory values, the uncertainty combines statistical, PDF, and renormalization/factorization scale components.
Measured differential cross section dsigma/dET in pb/GeV given (0.05 < DeltaR < 0.5). For the data values, the first uncertainty is statistical and the second is systematic. For the theory values, the uncertainty combines statistical, PDF, and renormalization/factorization scale components.
Measured differential cross section dsigma/dET in pb/GeV given (0.5 < DeltaR < 3.0). For the data values, the first uncertainty is statistical and the second is systematic. For the theory values, the uncertainty combines statistical, PDF, and renormalization/factorization scale components.
The production cross section for a W boson and two b jets is measured using proton-proton collisions at sqrt(s) = 7 TeV in a data sample collected with the CMS experiment at the LHC corresponding to an integrated luminosity of 5.0 inverse femtobarns. The W + b b-bar events are selected in the W to mu nu decay mode by requiring a muon with transverse momentum pt > 25 GeV and pseudorapidity abs(eta) < 2.1, and exactly two b-tagged jets with pt > 25 GeV and abs(eta) < 2.4. The measured W + b b-bar production cross section in the fiducial region, calculated at the level of final-state particles, is sigma(pp to W + b b-bar) x B(W to mu nu) = 0.53 +/- 0.05 (stat.) +/- 0.09 (syst.) +/- 0.06 (theo.) +/- 0.01 (lum.) pb, in agreement with the standard model prediction. In addition, kinematic distributions of the W + b b-bar system are in agreement with the predictions of a simulation using MADGRAPH and PYTHIA.
The measured $W+b\bar{b}$ cross section.
Parameters for theoretical comparison: theoretical $W+b\bar{b}$ cross section from MCFM and the two corrections (additive double parton scattering cross section estimation at the parton jet level, and multiplicative hadronization correction factor $C_{b\rightarrow B}$ ) that need to be applied in this order to it to compare to the observed cross section.
The double-differential cross sections of promptly produced J/psi and psi(2S) mesons are measured in pp collisions at sqrt(s) = 7 TeV, as a function of transverse momentum pt and absolute rapidity abs(y). The analysis uses J/psi and psi(2S) dimuon samples collected by CMS, corresponding to integrated luminosities of 4.55 and 4.90 inverse femtobarns, respectively. The results are based on a two-dimensional analysis of the dimuon invariant mass and decay length, and extend to pt = 120 and 100 GeV for the J/psi and psi(2S), respectively, when integrated over the interval abs(y) < 1.2. The ratio of the psi(2S) to J/psi cross sections is also reported for abs(y) < 1.2, over the range 10 < pt < 100 GeV. These are the highest pt values for which the cross sections and ratio have been measured.
J/psi double-differential cross section times branching fraction assuming unpolarized production as a function of pT and y for 0.0 < |y| < 0.3, 0.3 < |y| < 0.6, 0.6 < |y| < 0.9 and 0.9 < |y| < 1.2.
psi(2S) double-differential cross section times branching fraction assuming unpolarized production as a function of pT and y for 0.0 < |y| < 0.3, 0.3 < |y| < 0.6, 0.6 < |y| < 0.9 and 0.9 < |y| < 1.2.
J/psi double-differential cross section times branching fraction and the corresponding scaling factors to obtain the cross sections for different polarization scenarios (azimuthal polarization parameter in the center of mass helicity frame lambda_theta^HX = +1, -1, +0.1) as a function of pT for |y| < 1.2.
A search is conducted for non-resonant new phenomena in dielectron and dimuon final states, originating from either contact interactions or large extra spatial dimensions. The LHC 2012 proton-proton collision dataset recorded by the ATLAS detector is used, corresponding to 20 fb$^{-1}$ at $\sqrt{s}$ = 8 TeV. The dilepton invariant mass spectrum is a discriminating variable in both searches, with the contact interaction search additionally utilizing the dilepton forward-backward asymmetry. No significant deviations from the Standard Model expectation are observed. Lower limits are set on the $\ell\ell q q$ contact interaction scale $\Lambda$ between 15.4 TeV and 26.3 TeV, at the 95% credibility level. For large extra spatial dimensions, lower limits are set on the string scale $M_{S}$ between 3.2 TeV to 5.0 TeV.
Reconstructed dielectron mass distributions for data and the SM background estimate.
Reconstructed dimuon mass distributions for data and the SM background estimate.
Reconstructed $\cos\theta^*$ distributions for data and the SM background estimate in the dielectron channel.
Measurements of the differential and double-differential Drell-Yan cross sections in the dielectron and dimuon channels are presented. They are based on proton-proton collision data at sqrt(s) = 8 TeV recorded with the CMS detector at the LHC and corresponding to an integrated luminosity of 19.7 inverse femtobarns. The measured inclusive cross section in the Z peak region (60-120 GeV), obtained from the combination of the dielectron and dimuon channels, is 1138 +/- 8 (exp) +/- 25 (theo) +/- 30 (lumi) pb, where the statistical uncertainty is negligible. The differential cross section d(sigma)/d(m) in the dilepton mass range 15 to 2000 GeV is measured and corrected to the full phase space. The double-differential cross section d2(sigma)/d(m)d(abs(y)) is also measured over the mass range 20 to 1500 GeV and absolute dilepton rapidity from 0 to 2.4. In addition, the ratios of the normalized differential cross sections measured at sqrt(s) = 7 and 8 TeV are presented. These measurements are compared to the predictions of perturbative QCD at next-to-leading and next-to-next-to-leading (NNLO) orders using various sets of parton distribution functions (PDFs). The results agree with the NNLO theoretical predictions computed with FEWZ 3.1 using the CT10 NNLO and NNPDF2.1 NNLO PDFs. The measured double-differential cross section and ratio of normalized differential cross sections are sufficiently precise to constrain the proton PDFs.
Absolute Drell-Yan cross section measurements in the Z peak region (60 < m < 120 GeV). The uncertainties in the measurements include the experimental and theoretical systematic sources and the uncertainty in the integrated luminosity. The statistical component is negligible.
The Drell-Yan differential pre-FSR cross section D(SIG)/DM as measured in the combined dilepton channel for the full phase space. Theoretical uncertainty on acceptance is included.
The Drell-Yan pre-FSR dilepton rapidity distribution D(SIG)/DABS(YRAP) within the detector acceptance, for the mass bin 20-30 GeV, as measured in the combined dilepton channel.
Production of prompt J/$\psi$ meson pairs in proton-proton collisions at $\sqrt{s}$ = 7 TeV is measured with the CMS experiment at the LHC in a data sample corresponding to an integrated luminosity of about 4.7 inverse-femtobarns. The two J/$\psi$ mesons are fully reconstructed via their decays into $\mu^+\mu^-$ pairs. This observation provides for the first time access to the high-transverse-momentum region of J/$\psi$ pair production where model predictions are not yet established. The total and differential cross sections are measured in a phase space defined by the individual J/$\psi$ transverse momentum ($p_T^{J/\psi}$) and rapidity (|$y^{J/\psi}$|): |$y^{J/\psi}$| lower than 1.2 for $p_T^{J/\psi}$ greater than 6.5 GeV/c; |$y^{J/\psi}$| in [1.2,1.43] for a $p_T$ threshold that scales linearly with |$y^{J/\psi}$| from 6.5 to 4.5 GeV/c; and |$y^{J/\psi}$| in [1.43,2.2] for $p_T^{J/\psi}$ greater than 4.5 GeV/c. The total cross section, assuming unpolarized prompt J/$\psi$ pair production is 1.49 $\pm$ 0.07 (stat.) $\pm$ 0.13 (syst.) nb. Different assumptions about the J/$\psi$ polarization imply modifications to the cross section ranging from -31% to +27%.
Differential cross section D(SIG)/DM(J/PSI J/PSI) in bins of the J/PSI pair invariant mass, M(J/PSI J/PSI).
Differential cross section D(SIG)/DABS(DELTA(YRAP)) in bins of the absolute rapidity difference between J/PSI mesons, ABS(DELTA(YRAP)).
Differential cross section D(SIG)/DPT(J/PSI J/PSI) in bins of the transverse momentum of the J/PSI pair, PT(J/PSI J/PSI).
The polarizations of prompt J/psi and psi(2S) mesons are measured in proton-proton collisions at sqrt(s) = 7 TeV, using a dimuon data sample collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 4.9 inverse femtobarns. The prompt J/psi and psi(2S) polarization parameters lambda[theta], lambda[phi], and lambda[theta,phi], as well as the frame-invariant quantity lambda(tilde), are measured from the dimuon decay angular distributions in three different polarization frames. The J/psi results are obtained in the transverse momentum range 14 < pt < 70 GeV, in the rapidity intervals abs(y) < 0.6 and 0.6 < abs(y) < 1.2. The corresponding psi(2S) results cover 14 < pt < 50 GeV and include a third rapidity bin, 1.2 < abs(y) < 1.5. No evidence of large transverse or longitudinal polarizations is seen in these kinematic regions, which extend much beyond those previously explored.
Lambda-Theta in the CS frame for the J/psi as a function of pT for 0.0 < |y| < 0.6.
Lambda-Theta in the CS frame for the J/psi as a function of pT for 0.6 < |y| < 1.2.
Lambda-Phi in the CS frame for the J/psi as a function of pT for 0.0 < |y| < 0.6.
The production of a W boson in association with a single charm quark is studied using 4.6 fb^-1 of pp collision data at sqrt(s)=7 TeV collected with the ATLAS detector at the Large Hadron Collider. In events in which a W boson decays to an electron or muon, the charm quark is tagged either by its semileptonic decay to a muon or by the presence of a charmed meson. The integrated and differential cross sections as a function of the pseudorapidity of the lepton from the W-boson decay are measured. Results are compared to the predictions of next-to-leading-order QCD calculations obtained from various parton distribution function parameterisations. The ratio of the strange-to-down sea-quark distributions is determined to be 0.96 +0.26 -0.30 at Q^2=1.9 GeV^2, which supports the hypothesis of an SU(3)-symmetric composition of the light-quark sea. Additionally, the cross-section ratio sigma(W^+ + bar{c})/sigma(W^- + c) is compared to the predictions obtained using parton distribution function parameterisations with different assumptions about the s-bar{s} quark asymmetry.
Measured integrated cross sections of the production of a W boson with a single c-jet, a D meson or a D* meson times the branching ratio W -> l nu in the fiducial regions together with the statistical and systematic uncertainties. For the W+c-jet cross sections events with more than one c-jet are discarded. The particle-level c-jet is defined as the one containing a weakly decaying c-hadron with pt>5 GeV, within DeltaR<0.3. Jets containing c-hadrons originating from b-hadron decays are not counted as c-jets. Jets are not required for the W+D/D* cross sections. The cross sections are defined for OS-SS events.
Measured integrated cross section ratios of the production of W+ and W- bosons associated with a single c-jet, a D meson or a D* meson in the fiducial regions together with the statistical and systematic uncertainties. For the W+c-jet cross sections events with more than one c-jet are discarded. The particle-level c-jet is defined as the one containing a weakly decaying c-hadron with pt>5 GeV, within DeltaR<0.3. Jets containing c-hadrons originating from b-hadron decays are not counted as c-jets. Jets are not required for the W+D/D* cross sections. The cross sections are defined for OS-SS events.
Measured differential cross sections as function of the lepton pseudo-rapidity of the production of a W boson with a single c-jet times the branching ratio W -> l nu in the fiducial regions together with the statistical and systematic uncertainties. For the W+c-jet cross sections events with more than one c-jet are discarded. The particle-level c-jet is defined as the one containing a weakly decaying c-hadron with pt>5 GeV, within DeltaR<0.3. Jets containing c-hadrons originating from b-hadron decays are not counted as c-jets. The cross sections are defined for OS-SS events.
The normalised differential top quark-antiquark production cross section is measured as a function of the jet multiplicity in proton-proton collisions at a centre-of-mass energy of 7 TeV at the LHC with the CMS detector. The measurement is performed in both the dilepton and lepton + jets decay channels using data corresponding to an integrated luminosity of 5.0 inverse femtobarns. Using a procedure to associate jets to decay products of the top quarks, the differential cross section of the t t-bar production is determined as a function of the additional jet multiplicity in the lepton + jets channel. Furthermore, the fraction of events with no additional jets is measured in the dilepton channel, as a function of the threshold on the jet transverse momentum. The measurements are compared with predictions from perturbative quantum chromodynamics and no significant deviations are observed.
Normalised differential TOP TOPBAR production cross section as a function of the jet multiplicity for jets with PT(JET) > 30 GeV in the dilepton channel. The statistical and main experimental and model systematic uncertainties are displayed.
Normalised differential TOP TOPBAR production cross section as a function of the jet multiplicity for jets with PT(JET) > 60 GeV in the dilepton channel. The statistical and main experimental and model systematic uncertainties are displayed.
Normalised differential TOP TOPBAR production cross section as a function of the jet multiplicity for jets with PT(JET) > 35 GeV in the lepton+jets channel. The statistical and main experimental and model systematic uncertainties are displayed.
This paper describes a measurement of the $Z/\gamma^*$ boson transverse momentum spectrum using ATLAS proton-proton collision data at a centre-of-mass energy of $\sqrt{s}$ = 7 TeV at the LHC. The measurement is performed in the $Z/\gamma^* \rightarrow e^+e^-$ and $Z/\gamma^* \rightarrow \mu^+\mu^-$ channels, using data corresponding to an integrated luminosity of 4.7 fb$^{-1}$. Normalized differential cross sections as a function of the $Z/\gamma^*$ boson transverse momentum are measured for transverse momenta up to 800 GeV. The measurement is performed inclusively for $Z/\gamma^*$ rapidities up to 2.4, as well as in three rapidity bins. The channel results are combined, compared to perturbative and resummed QCD calculations and used to constrain the parton shower parameters of Monte Carlo generators.
The measured normalized cross section (1/SIG(FID))*D(SIG(FID))/DPT(Z) at the Born level in bins of PT(Z) for the Z/GAMMA* --> E+ E- and Z/GAMMA* --> MU+ MU- channels, and correction factors to the bare- and dressed-level cross sections. The relative statistical and total uncorrelated systematic uncertainties are given for each channel as well as the correlated systematic uncertainties.
The measured normalized combined (electron and muon channels) cross section (1/SIG(FID))*D(SIG(FID))/DPT(Z) inclusive in rapidity. The cross sections at Born and dressed levels are given as well as the relative statistical and total uncorrelated systematic uncertainties as well as the correlated systematic uncertainties.
The measured normalized combined (electron and muon channels) cross section (1/SIG(FID))*D(SIG(FID))/DPT(Z) for 0 <= ABS(YRAP(Z)) < 1, 1 <= ABS(YRAP(Z)) < 2 and 2 <= ABS(YRAP(Z)) < 2.4. The cross sections at Born and dressed levels are given as well as the relative statistical and systematic uncertainties for uncorrelated and correlated sources.
The process pp--> W + J/psi provides a powerful probe of the production mechanism of charmonium in hadronic collisions, and is also sensitive to multiple parton interactions in the colliding protons. Using the 2011 ATLAS dataset of 4.5 fb-1 of sqrt{s} = 7 TeV pp collisions at the LHC, the first observation is made of the production of W + prompt J/psi events in hadronic collisions, using W-->mu+nu and J/psi-->mu+mu. A yield of 27.4+7.5-6.5 W + prompt J/psi events is observed, with a statistical significance of 5.1 sigma. The production rate as a ratio to the inclusive W boson production rate is measured, and the double parton scattering contribution to the cross section is estimated.
The W + prompt J/psi to inclusive W production cross-section ratio (times 10^6) in the J/psi fiducial region (Fiducial), after correction for J/psi acceptance (Inclusive), and after subtraction of the double parton scattering component (DPS-subtracted). The first uncertainty is statistical, the second is systematic, and the third/fourth (where applicable) is the uncertainty up/down due to spin-alignment.
The inclusive (SPS+DPS) cross-section ratio (times 10^6) as a function of J/psi transverse momentum, along with the estimate of the DPS contribution. For the inclusive result, the first uncertainty is statistical, second uncertainty is systematic, and the third uncertainty is the possible variation due to spin-alignment.
The inclusive (SPS+DPS) cross-section ratio (times 10^6) as a function of J/psi transverse momentum under the LONGITUDINAL spin-alignment hypothesis. The first uncertainty is statistical and the second uncertainty is systematic.
Measurements of the differential and double-differential Drell-Yan cross sections are presented using an integrated luminosity of 4.5(4.8) inverse femtobarns in the dimuon (dielectron) channel of proton-proton collision data recorded with the CMS detector at the LHC at $\sqrt{s}$ = 7 TeV. The measured inclusive cross section in the Z-peak region (60-120 GeV) is $\sigma(\ell \ell)$ = 986.4 +/- 0.6 (stat.) +/- 5.9 (exp. syst.) +/- 21.7 (th. syst.) +/- 21.7 (lum.) pb for the combination of the dimuon and dielectron channels. Differential cross sections $d\sigma/dm$ for the dimuon, dielectron, and combined channels are measured in the mass range 15 to 1500 GeV and corrected to the full phase space. Results are also presented for the measurement of the double-differential cross section $d^2\sigma/dm d |y|$ in the dimuon channel over the mass range 20 to 1500 GeV and absolute dimuon rapidity from 0 to 2.4. These measurements are compared to the predictions of perturbative QCD calculations at next-to-leading and next-to-next-to-leading orders using various sets of parton distribution functions.
Normalization factors for the cross section measurements from the Z-peak region (60 < M < 120 GeV) with associated uncertainties. The measurements are given in the muon, electron and combined channels. The three systematic uncertainties correspond to experimental, theoretical and luminosity.
The DY cross section measurements for the muon channel normalized to the Z-peak region, pre- and post-FSR, as measured in the full acceptance and for the CMS detector acceptance. The uncertainty indicates the experimental (statistical and systematic) uncertainties summed in quadrature with the theoretical uncertainty resulting from the model-dependent kinematic distributions inside each bin.
The DY cross section measurements for the electron channel normalized to the Z-peak region, pre- and post-FSR, as measured in the full acceptance and for the CMS detector acceptance. The uncertainty indicates the experimental (statistical and systematic) uncertainties summed in quadrature with the theoretical uncertainty resulting from the model-dependent kinematic distributions inside each bin.
This Letter presents a search for quantum black-hole production using 20.3 inverse fb of data collected with the ATLAS detector in pp collisions at the LHC at sqrt(s) = 8 TeV. The quantum black holes are assumed to decay into a lepton (electron or muon) and a jet. In either channel, no event with a lepton-jet invariant mass of 3.5 TeV or more is observed, consistent with the expected background. Limits are set on the product of cross sections and branching fractions for the lepton+jet final states of quantum black holes produced in a search region for invariant masses above 1 TeV. The combined 95% confidence level upper limit on this product for quantum black holes with threshold mass above 3.5 TeV is 0.18 fb. This limit constrains the threshold quantum black-hole mass to be above 5.3 TeV in the model considered.
The combined 95% CL upper limits on the cross section times branching fraction (SIG*BR) for Quantum Black Holes decaying to a lepton and jet, as a function of the threshold mass, Mth.
Numbers of observed events and expected background events for electron+jet channel, along with acceptance (A), experimental efficiency (EPSILON), cumulative efficiency (A*EPSILON), total cross section (SIG*BR) and 95% CL observed upper limit, for various values of the threshold mass, Mth. The leading order cross sections have a statistical precision of the order of 1%. The uncertainties on the predicted background include both statistical and systematic components. Acceptance is calculated using generator-level quantities by imposing selection criteria that apply directly to phase space (electron/jet eta, electron/jet pT, Delta(eta), Delta(phi), <eta>, and Minv). All other selections, which in general correspond to event and object quality criteria, are used to calculate the efficiency on the events included in the acceptance. The cumulative signal efficiency is the product of the acceptance and experimental efficiency.
Numbers of observed events and expected background events for muon+jet channel, along with acceptance (A), experimental efficiency (EPSILON), cumulative efficiency (A*EPSILON), total cross section (SIG*BR) and 95% CL observed upper limit, for various values of the threshold mass, Mth. The leading order cross sections have a statistical precision of the order of 1%. The uncertainties on the predicted background include both statistical and systematic components. Acceptance is calculated using generator-level quantities by imposing selection criteria that apply directly to phase space (muon/jet eta, muon/jet pT, Delta(eta), Delta(phi), <eta>, and Minv). All other selections, which in general correspond to event and object quality criteria, are used to calculate the efficiency on the events included in the acceptance. The cumulative signal efficiency is the product of the acceptance and experimental efficiency.
A measurement of angular correlations in Drell-Yan lepton pairs via the phistar observable is presented. This variable probes the same physics as the Z/gamma* boson transverse momentum with a better experimental resolution. The Z/gamma*->e+e- and Z/gamma*->mu+mu- decays produced in proton--proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV are used. The data were collected with the ATLAS detector at the LHC and correspond to an integrated luminosity of 4.6 fb-1. Normalised differential cross sections as a function of phistar are measured separately for electron and muon decay channels. These channels are then combined for improved accuracy. The cross section is also measured double differentially as a function of phistar for three independent bins of the Z boson rapidity. The results are compared to QCD calculations and to predictions from different Monte Carlo event generators. The data are reasonably well described, in all measured Z boson rapidity regions, by resummed QCD predictions combined with fixed-order perturbative QCD calculations. Some of the Monte Carlo event generators are also able to describe the data. The measurement precision is typically better by one order of magnitude than present theoretical uncertainties.
The measured PHI* distributions for the dielectron events corrected back to the born level. The distributions are normalised to unity inidividually for each abs(yrap) bin and channel.
The measured PHI* distributions for the dielectron events corrected back to the dress level. The distributions are normalised to unity inidividually for each abs(yrap) bin and channel.
The measured PHI* distributions for the dielectron events corrected back to the bare particle level. The distributions are normalised to unity inidividually for each abs(yrap) bin and channel.
The $\Upsilon$(1S), $\Upsilon$(2S), and $\Upsilon$(3S) production cross sections are measured using a data sample corresponding to an integrated luminosity of 35.8 $\pm$ 1.4 inverse picobarns of proton-proton collisions at $\sqrt{s}$ = 7 TeV, collected with the CMS detector at the LHC. The Upsilon resonances are identified through their decays to dimuons. Integrated over the $\Upsilon$ transverse momentum range $p_{t}^{\Upsilon} \lt$ 50GeV and rapidity range |$y^\Upsilon$| $\lt$ 2.4, and assuming unpolarized Upsilon production, the products of the Upsilon production cross sections and dimuon branching fractions are \begin{equation*}\sigma(pp \to \Upsilon(1S) X) . B(\Upsilon(1S) \to \mu^+ \mu^-) = (8.55 \pm 0.05^{+0.56}_{-0.50} \pm 0.34) nb,\end{equation*} \begin{equation*}\sigma(pp \to \Upsilon(2S) X) . B(\Upsilon(2S) \to \mu^+ \mu^-) = (2.21 \pm 0.03^{+0.16}_{-0.14} \pm 0.09) nb,\end{equation*} \begin{equation*}\sigma(pp \to \Upsilon(3S) X) . B(\Upsilon(3S) \to \mu^+ \mu^-) = (1.11 \pm 0.02^{+0.10}_{-0.08} \pm 0.04) nb, \end{equation*} where the first uncertainty is statistical, the second is systematic, and the third is from the uncertainty in the integrated luminosity. The differential cross sections in bins of transverse momentum and rapidity, and the cross section ratios are presented. Cross section measurements performed within a restricted muon kinematic range and not corrected for acceptance are also provided. These latter measurements are independent of Upsilon polarization assumptions. The results are compared to theoretical predictions and previous measurements.
The fiducial and acceptance-corrected cross sections for PT<50 GeV/c and |rapidity|<2.4.
The fiducial and acceptance corrected UPSI(1S) production cross sections (times di-muon branching ratio) as a function of PT for the |rapidity| range < 2.4. Note these are integrated cross sections and the acceptance-corrected cross sections assume the UPSI(1S) are unpolarized with the variations due to the 4 extreme polarization scenarios shown in the last 4 columns. The fiducial cross sections do not need to make any assumptions on the polarizations scenarios. The luminosity uncertainty of 4% is not included in the systematic errors.
The fiducial and acceptance corrected UPSI(2S) production cross sections (times di-muon branching ratio) as a function of PT for the |rapidity| range < 2.4. Note these are integrated cross sections and the acceptance-corrected cross sections assume the UPSI(2S) are unpolarized with the variations due to the 4 extreme polarization scenarios shown in the last 4 columns. The fiducial cross sections do not need to make any assumptions on the polarizations scenarios. The luminosity uncertainty of 4% is not included in the systematic errors.
The production cross-section of B+ mesons is measured as a function of transverse momentum pT and rapidity y in proton--proton collisions at center-of-mass energy sqrt(s) = 7 TeV, using 2.4 fb-1 of data recorded with the ATLAS detector at the Large Hadron Collider. The differential production cross-sections, determined in the range 9<pT<120 GeV and y<2.25, are compared to next-to-leading-order theoretical predictions.
Differential cross-section measurement for B+ production multiplied by the branching ratio to the J/PSI < MU+ MU- > K+ final state in B+ pT intervals in the B+ rapidity range |y|<0.5. The first quoted uncertainty is statistical, the second uncertainty is systematic.
Differential cross-section measurement for B+ production multiplied by the branching ratio to the J/PSI < MU+ MU- > K+ final state in B+ pT intervals in the B+ rapidity range 0.5<|y|<1. The first quoted uncertainty is statistical, the second uncertainty is systematic.
Differential cross-section measurement for B+ production multiplied by the branching ratio to the J/PSI < MU+ MU- > K+ final state in B+ pT intervals in the B+ rapidity range 1<|y|<1.5 The first quoted uncertainty is statistical, the second uncertainty is systematic.
The differential cross section for the process $Z/\gamma^*\rightarrow ll$ ($l=e,\mu$) as a function of dilepton invariant mass is measured in pp collisions at $\sqrt{s}=$ 7 TeV at the LHC using the ATLAS detector. The measurement is performed in the $e$ and $\mu$ channels for invariant masses between 26 GeV and 66 GeV using an integrated luminosity of 1.6 fb$^{-1}$ collected in 2011 and these measurements are combined. The analysis is extended to invariant masses as low as 12 GeV in the muon channel using 35 pb$^{-1}$ of data collected in 2010. The cross sections are determined within fiducial acceptance regions and corrections to extrapolate the measurements to the full kinematic range are provided. Next-to-next-to-leading-order QCD predictions provide a significantly better description of the results than next-to-leading-order QCD calculations, unless the latter are matched to a parton shower calculation.
The nominal electron-channel differential Born-level fiducial cross section. The statistical and systematic uncertainties are given for each invariant mass bin. The luminosity uncertainty 1.8% is not included.
The systematic uncertainties of the nominal electron-channel cross-section measurement. Some sources of uncertainty have both correlated and uncorrelated components. Correlated uncertainties arise from the uncertainty in the electroweak background contributions delta(e.w.)_cor, from corrections to the Monte Carlo modelling of the Z/gamma* pT spectra, delta(pTrw)_cor, the electron identification efficiency, delta(id)_cor1 and delta(id)_cor2, the reconstruction efficiency, delta(rec)_cor, and from the Geant4 simulation, delta(geant4)_cor. Uncorrelated uncertainties arise from the isolation and trigger efficiency corrections, delta(trig) and delta(iso) respectively, unfolding uncertainties, delta(res)_unf, and the statistical precision of the signal Monte Carlo, delta(MC). The electron identification efficiency uncertainties have several components other than the two largest correlated parts above. These additional components are all combined into a single uncorrelated error source delta(id)_unc. The uncertainty on the normalisation of the multijet background is given by delta(multijet). The luminosity uncertainty 1.8% is not included.
The nominal muon-channel differential Born-level fiducial cross section. The statistical, systematic, and total uncertainties are given for each invariant mass bin. The luminosity uncertainty 1.8% is not included.
The production of $Z$ bosons with one or two isolated high-energy photons is studied using $pp$ collisions at $\sqrt{s}$ = 8 TeV. The analyses use a data sample with an integrated luminosity of 20.3 fb$^{-1}$ collected by the ATLAS detector during the 2012 LHC data taking. The $Z\gamma$ and $Z\gamma\gamma$ production cross sections are measured with leptonic ($e^{+}e^{-}$, $\mu^{+}\mu^{-}$, $\nu\bar{\nu}$) decays of the $Z$ boson, in extended fiducial regions defined in terms of the lepton and photon acceptance. They are then compared to cross-section predictions from the Standard Model, where the sources of the photons are radiation off initial-state quarks and radiative $Z$-boson decay to charged leptons, and from fragmentation of final-state quarks and gluons into photons. The yields of events with photon transverse energy $E_T >$ 250 GeV from $\ell^{+}\ell^{-}\gamma$ events and with $E_T >$ 400 GeV from $\nu\bar{\nu}\gamma$ events are used to search for anomalous triple gauge-boson couplings $ZZ\gamma$ and $Z\gamma\gamma$. The yields of events with diphoton invariant mass $m_{\gamma\gamma} >$ 200 GeV from $\ell^{+}\ell^{-}\gamma\gamma$ events and with $m_{\gamma\gamma} > $ 300 GeV from $\nu\bar{\nu}\gamma\gamma$ events are used to search for anomalous quartic gauge-boson couplings $ZZ\gamma\gamma$ and $Z\gamma\gamma\gamma$. No deviations from Standard Model predictions are observed and limits are placed on parameters used to describe anomalous triple and quartic gauge-boson couplings.
Measured integrated cross sections for the $Z\gamma$ process for charged lepton final states at $\sqrt{s} = 8$ TeV in the extended fiducial regions defined in the paper, table 5. The parton-to-particle correction factors are also shown, which are defined as the ratio of the cross sections at parton-level to the cross sections at particle-level.
Measured integrated cross sections for the $Z\gamma$ process for neutrino final states at $\sqrt{s} = 8$ TeV in the extended fiducial regions defined in the paper, table 5. The parton-to-particle correction factors are also shown, which are defined as the ratio of the cross sections at parton-level to the cross sections at particle-level.
Measured integrated cross sections for the $Z\gamma\gamma$ process for charged lepton final states at $\sqrt{s} = 8$ TeV in the extended fiducial regions defined in the paper, table 5. The parton-to-particle correction factors are also shown, which are defined as the ratio of the cross sections at parton-level to the cross sections at particle-level.
The production rates of prompt and non-prompt $J/\psi$ and $\psi(2\mathrm{S})$ mesons are measured using 2.1 $fb^{-1}$ and 11.4 $fb^{-1}$ of data collected with the ATLAS experiment at the LHC, in proton-proton collisions at $\sqrt{s}=7$ and 8 TeV respectively. Production cross-sections for both prompt and non-prompt production sources, ratios of $\psi(2\mathrm{S})$ to $J/\psi$ production, and fractions of non-prompt to inclusive production for $J/\psi$ and $\psi(2\mathrm{S})$ are measured double-differentially as a function of meson $p_{T}$ and rapidity. These measurements are made in a restricted fiducial volume and also corrected for geometrical acceptance after which they are compared to a variety of theoretical predictions.
Summary of results for cross-section of prompt $J/\psi$ decaying to a muon pair for 7 TeV data in nb/GeV. Uncertainties are statistical and systematic, respectively.
Summary of results for cross-section of prompt $J/\psi$ decaying to a muon pair for 8 TeV data in nb/GeV. Uncertainties are statistical and systematic, respectively.
Summary of results for cross-section of non-prompt $J/\psi$ decaying to a muon pair for 7 TeV data in nb/GeV. Uncertainties are statistical and systematic, respectively.
Distributions of transverse momentum $p_T^{ll}$ and the angular variable $\phi^*_\eta$ of Drell--Yan lepton pairs are measured in 20.3 fb$^{-1}$ of proton--proton collisions at $\sqrt{s}=8$ TeV with the ATLAS detector at the LHC. Measurements in electron-pair and muon-pair final states are corrected for detector effects and combined. Compared to previous measurements in proton--proton collisions at $\sqrt{s}=7$ TeV, these new measurements benefit from a larger data sample and improved control of systematic uncertainties. Measurements are performed in bins of lepton-pair mass above, around and below the Z-boson mass peak. The data are compared to predictions from perturbative and resummed QCD calculations. For values of $\phi^*_\eta < 1$ the predictions from the Monte Carlo generator ResBos are generally consistent with the data within the theoretical uncertainties. However, at larger values of $\phi^*_\eta$ this is not generally the case. Monte Carlo generators based on the parton-shower approach are unable to describe the data over the full range of $p_T^{ll}$ and the fixed-order prediction of DYNNLO falls below the data at high values of $p_T^{ll}$. ResBos and the parton-shower Monte Carlo generators provide a much better description of the evolution of the $\phi^*_\eta$ and $p_T^{ll}$ distributions as a function of lepton-pair mass and rapidity.
Fiducial cross sections at Born level in the electron- and muon-pair channels as well as the combined value. The statistical and systematic uncertainties are given as a percentage of the cross section. An additional uncertainty of 2.8% on the integrated luminosity, which is fully correlated between channels and among all $m_{\ell\ell}$ bins, pertains to these measurements. The individual uncertainty sources after the combination are not necessarily orthogonal and also do not include uncertainties uncorrelated between bins of $m_{\ell\ell}$. Therefore their quadratic sum may not give the total systematic uncertainty.
The values of $(1/\sigma)\,\mathrm{d}\sigma/\mathrm{d}\phi^*_{\eta}$ in each bin of $\phi^*_{\eta}$ for the electron and muon channels separately (for various particle-level definitions) and for the Born-level combination in the kinematic region $46\textrm{ GeV} \leq m_{\ell\ell} < 66\textrm{ GeV},\ 0 \leq |y_{\ell\ell}| < 0.8$. The associated statistical and systematic (both uncorrelated and correlated between bins of $\phi^*_{\eta}$) are provided in percentage form.
The values of $(1/\sigma)\,\mathrm{d}\sigma/\mathrm{d}\phi^*_{\eta}$ in each bin of $\phi^*_{\eta}$ for the electron and muon channels separately (for various particle-level definitions) and for the Born-level combination in the kinematic region $46\textrm{ GeV} \leq m_{\ell\ell} < 66\textrm{ GeV},\ 0.8 \leq |y_{\ell\ell}| < 1.6$. The associated statistical and systematic (both uncorrelated and correlated between bins of $\phi^*_{\eta}$) are provided in percentage form.
The $ZZ$ production cross section in proton-proton collisions at 13 TeV center-of-mass energy is measured using 3.2 fb$^{-1}$ of data recorded with the ATLAS detector at the Large Hadron Collider. The considered $Z$ boson candidates decay to an electron or muon pair of mass 66-116 GeV. The cross section is measured in a fiducial phase space reflecting the detector acceptance. It is also extrapolated to a total phase space for $Z$ bosons in the same mass range and of all decay modes, giving $16.7^{+2.2}_{-2.0}$(stat.)$^{+0.9}_{-0.7}$(syst.)$^{+1.0}_{-0.7}$(lumi.) pb. The results agree with standard model predictions.
Measured fiducial cross section in the $e^+e^-e^+e^-$ channel. The first systematic uncertainty is the combined systematic uncertainty excluding luminosity uncertainty, the second is the luminosity uncertainty.
Measured fiducial cross section in the $e^+e^-\mu^+\mu^-$ channel. The first systematic uncertainty is the combined systematic uncertainty excluding luminosity uncertainty, the second is the luminosity uncertainty.
Measured fiducial cross section in the $\mu^+\mu^-\mu^+\mu^-$ channel. The first systematic uncertainty is the combined systematic uncertainty excluding luminosity uncertainty, the second is the luminosity uncertainty.
A search for neutral Higgs bosons predicted in the minimal supersymmetric standard model (MSSM) for mu+ mu- decay channels is presented. The analysis uses data collected by the CMS experiment at the LHC in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV, corresponding to integrated luminosities of 5.1 and 19.3 inverse femtobarns, respectively. The search is sensitive to Higgs bosons produced through the gluon fusion process or in association with a bb quark pair. No statistically significant excess is observed in the mu+ mu- mass spectrum. Results are interpreted in the framework of several benchmark scenarios, and the data are used to set an upper limit on the MSSM parameter tan(beta) as a function of the mass of the pseudoscalar A boson in the range from 115 to 300 GeV. Model independent upper limits are given for the product of the cross section and branching fraction for gluon fusion and b quark associated production. They are the most stringent limits obtained to date in this channel.
The 95% CL upper limit on tan B as a function of mA, after combining the data from the two event categories at the two centre-of-mass energies (7 and 8 TeV). The results are obtained in the framework of the mh-mod+ benchmark scenario.
The 95% CL limit on the product of the cross section and the decay branching fraction to two muons as a function of mPHI, obtained from a model independent analysis of the data. The results refer to b quark associated production, obtained using data collected at swrt(s) = 8 TeV.
The 95% CL limit on the product of the cross section and the decay branching fraction to two muons as a function of mPHI, obtained from a model independent analysis of the data. The results refer to gluon-fusion production, obtained using data collected at swrt(s) = 8 TeV.
A search for supersymmetry (SUSY) in events with large missing transverse momentum, jets, at least one hadronically decaying tau lepton and zero or one additional light leptons (electron/muon), has been performed using 20.3 fb$^{-1}$ of proton-proton collision data at $\sqrt{s} = 8$ TeV recorded with the ATLAS detector at the Large Hadron Collider. No excess above the Standard Model background expectation is observed in the various signal regions and 95% confidence level upper limits on the visible cross section for new phenomena are set. The results of the analysis are interpreted in several SUSY scenarios, significantly extending previous limits obtained in the same final states. In the framework of minimal gauge-mediated SUSY breaking models, values of the SUSY breaking scale $\Lambda$ below 63 TeV are excluded, independently of tan$\beta$. Exclusion limits are also derived for an mSUGRA/CMSSM model, in both the R-parity-conserving and R-parity-violating case. A further interpretation is presented in a framework of natural gauge mediation, in which the gluino is assumed to be the only light coloured sparticle and gluino masses below 1090 GeV are excluded.
Distribution of MTtau after all analysis requirements but the requirement on MTtau and the final requirement on HT for the 1tau ''Loose'' SR. The SM prediction includes the data-driven corrections discussed in the paper. MC events are normalized to data in the CRs corresponding to MTtau below 130 GeV. Also shown is the expected signal from typical mSUGRA, GMSB and bRPV samples. The last bin in the expected background distribution is an overflow bin.
Distribution of HT after the MTtau requirement for the 1-tau ''Loose'' SR. The SM prediction includes the data-driven corrections discussed in the paper. MC events are normalized to data in the CRs corresponding to MTtau below 130 GeV. Also shown is the expected signal from typical mSUGRA, GMSB and bRPV samples. The last bin in the expected background distribution is an overflow bin.
Distribution of MTtau after all analysis requirements but the requirement on MTtau and the final requirement on HT for the 1tau 'Tight'' SR. The SM prediction includes the data-driven corrections discussed in the paper. MC events are normalized to data in the CRs corresponding to MTtau below 130 GeV. Also shown is the expected signal from typical mSUGRA, GMSB and bRPV samples. The last bin in the expected background distribution is an overflow bin.
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