The PHENIX experiment at the Relativistic Heavy Ion Collider has measured the differential cross section, mean transverse momentum, mean transverse momentum squared of inclusive $J/\psi$ and cross-section ratio of $\psi(2S)$ to $J/\psi$ at forward rapidity in \pp collisions at \sqrts = 510 GeV via the dimuon decay channel. Comparison is made to inclusive $J/\psi$ cross sections measured at \sqrts = 200 GeV and 2.76--13 TeV. The result is also compared to leading-order nonrelativistic QCD calculations coupled to a color-glass-condensate description of the low-$x$ gluons in the proton at low transverse momentum ($p_T$) and to next-to-leading order nonrelativistic QCD calculations for the rest of the $p_T$ range. These calculations overestimate the data at low $p_T$. While consistent with the data within uncertainties above $\approx3$ GeV/$c$, the calculations are systematically below the data. The total cross section times the branching ratio is BR $d\sigma^{J/\psi}_{pp}/dy (1.2<|y|<2.2, 0<p_T<10~\mbox{GeV/$c$}) =$ 54.3 $\pm$ 0.5 (stat) $\pm$ 5.5 (syst) nb.
The total cross section times the branching ratio.
The inclusive $J/\psi$ differential cross section as a function of $p_T$ at 1.2 < $|y|$ < 2.2 at 510 GeV.
The inclusive $J/\psi$ differential cross section integrated over 0 < $p_T$ < 10 GeV/$c$ as a function of rapidity at 510 GeV.
We present a measurement of inclusive $J/\psi$ production at mid-rapidity ($|y|<1$) in $p+p$ collisions at a center-of-mass energy of $\sqrt{s}$ = 200 GeV with the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). The differential production cross section for $J/\psi$ as a function of transverse momentum ($p_T$) for $0
Top$:$ J/$\psi$ cross section times branching ratio as a function of pT in p+p collisions at $\sqrt{s_{NN}}$ = 200 GeV. Solid circles are from this analysis for |y| < 1; open circles and blue squares are the published results for |y| < 1 from STAR; triangles are the published results for |y| < 0.35 from PHENIX. Bars and boxes are statistical and systematic uncertainties, respectively. The curves are CEM (green), NLO NRQCD A (orange) [4], CGC + NRQCD (blue) , and NLO NRQCD B (magenta) theoretical calculations, respectively. Bottom$:$ ratios of these results with respect to the central value from this analysis.
The corrected $n_{ch}$ distributions at mid-rapidity (|$\eta$| < 1) for MB events (open circles) and J/$\psi$ events with J/$\psi$ $p_{T}$ greater than 0 (purple circles), 1.5 (blue squares), and 4 GeV/c (red triangles) in p+p collisions at $\sqrt{s}$ = 200 GeV. The fit function is a negative binomial function. Bars and boxes are statistical and systematic uncertainties, respectively.
The multiplicity dependence of J/$\psi$ production in p+p collisions at $\sqrt{s}$ = 200 GeV. Purple circles, blue squares, and red triangles represent the results for J/$\psi$ with $p_{T}$ greater than 0, 1.5, and 4 GeV/c, respectively. Bars and open boxes are statistical and systematic uncertainties, respectively. The ALICE result is shown in the left panel. The purple, blue and red bands in the middle panel are generated from PYTHIA8 for J/$\psi$ with $p_{T}$ greater than 0, 1.5, and 4 GeV/c, respectively. The blue and red bands in the right panel are from EPOS3 model calculations for D$^{0}$ with 2 < $p_{T}$ < 4 and 4 < $p_{T}$ < 8 GeV/c, respectively, while the green curve is from the Percolation model for J/$\psi$ with $p_{T}$ > 0 GeV/c.
The ALICE experiment has measured the inclusive J/$\psi$ production in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}} } = 2.76$ TeV down to zero transverse momentum in the rapidity range $2.5 < y < 4$. A suppression of the inclusive J/$\psi$ yield in Pb-Pb is observed with respect to the one measured in pp collisions scaled by the number of binary nucleon-nucleon collisions. The nuclear modification factor, integrated over the 0-80% most central collisions, is $0.545 \pm 0.032 \rm{(stat.)} \pm 0.083 \rm{(syst.)}$ and does not exhibit a significant dependence on the collision centrality. These features appear significantly different from measurements at lower collision energies. Models including J/$\psi$ production from charm quarks in a deconfined partonic phase can describe our data.
Jpsi Nuclear Modification Factor (Raa) measured in Pb-Pb collisions at sqrt(sNN) = 2.76 TeV in 2.5 < y < 4 and pt > 0 GeV/c, as a function of - the average number of participating nucleons (<Npart>), - the average number of participating nucleons (<Npart,w>) weigthed by the average number of binary collisions, - the mid-rapidity charged-particle density measured at pseudo-rapidity eta = 0 dNch,w/deta|eta=0 weigthed by the average number of binary collisions.
Centrality integrated (0%-80%) inclusive Jpsi Nuclear Modification Factor (Raa) measured in Pb-Pb collisions at sqrt(sNN) = 2.76 TeV as a function of rapidity for two transverse momentum ranges.
We report the measurement of $K^{*0}$ meson at midrapidity ($|y|<$ 1.0) in Au+Au collisions at $\sqrt{s_{\rm NN}}$~=~7.7, 11.5, 14.5, 19.6, 27 and 39 GeV collected by the STAR experiment during the RHIC beam energy scan (BES) program. The transverse momentum spectra, yield, and average transverse momentum of $K^{*0}$ are presented as functions of collision centrality and beam energy. The $K^{*0}/K$ yield ratios are presented for different collision centrality intervals and beam energies. The $K^{*0}/K$ ratio in heavy-ion collisions are observed to be smaller than that in small system collisions (e+e and p+p). The $K^{*0}/K$ ratio follows a similar centrality dependence to that observed in previous RHIC and LHC measurements. The data favor the scenario of the dominance of hadronic re-scattering over regeneration for $K^{*0}$ production in the hadronic phase of the medium.
$p_{\mathrm T}$-differential yield of $\mathrm{K^{*0}} + \bar{\mathrm{K^{*0}}}$ in AuAu collisions at $\sqrt{s_{\mathrm{NN}}}~=~$7.7 GeV (Multiplicity class 0-20%).
$p_{\mathrm T}$-differential yield of $\mathrm{K^{*0}} + \bar{\mathrm{K^{*0}}}$ in AuAu collisions at $\sqrt{s_{\mathrm{NN}}}~=~$7.7 GeV (Multiplicity class 20-40%).
$p_{\mathrm T}$-differential yield of $\mathrm{K^{*0}} + \bar{\mathrm{K^{*0}}}$ in AuAu collisions at $\sqrt{s_{\mathrm{NN}}}~=~$7.7 GeV (Multiplicity class 40-60%).
Using a data sample with a total integrated luminosity of 10.0 pb$^{-1}$ collected at center-of-mass energies of 2.6, 3.07 and 3.65 GeV with BESII, cross sections for $e^+e^-$ annihilation into hadronic final states ($R$ values) are measured with statistical errors that are smaller than 1%, and systematic errors that are about 3.5%. The running strong interaction coupling constants $\alpha_s^{(3)}(s)$ and $\alpha_s^{(5)}(M_Z^2)$ are determined from the $R$ values.
R values.
The ATLAS Collaboration has measured the inclusive production of $Z$ bosons via their decays into electron and muon pairs in $p+$Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV at the Large Hadron Collider. The measurements are made using data corresponding to integrated luminosities of 29.4 nb$^{-1}$ and 28.1 nb$^{-1}$ for $Z \rightarrow ee$ and $Z \rightarrow \mu\mu$, respectively. The results from the two channels are consistent and combined to obtain a cross section times the $Z \rightarrow \ell\ell$ branching ratio, integrated over the rapidity region $|y^{*}_{Z}|<3.5$, of 139.8 $\pm$ 4.8 (stat.) $\pm$ 6.2 (syst.) $\pm$ 3.8 (lumi.) nb. Differential cross sections are presented as functions of the $Z$ boson rapidity and transverse momentum, and compared with models based on parton distributions both with and without nuclear corrections. The centrality dependence of $Z$ boson production in $p+$Pb collisions is measured and analyzed within the framework of a standard Glauber model and the model's extension for fluctuations of the underlying nucleon-nucleon scattering cross section.
The centrality bias factors derived from data as explained in the text. Model calculations shown in the Figure are found in arXiv:1412.0976.
The differential $Z$ boson production cross section, $d\sigma/dy^\mathrm{*}_{Z}$, as a function of $Z$ boson rapidity in the center-of-mass frame $y^\mathrm{*}_{Z}$, for $Z\rightarrow ee$, $Z\rightarrow\mu\mu$, and their combination $Z\rightarrow\ell\ell$.
The differential cross section of $Z$ boson production multiplied by the Bjorken $x$ of the parton in the lead nucleus, $x_{Pb} d\sigma /dx_{Pb}$, as a function of $x_{Pb}$.
Measurements of $ZZ$ production in the $\ell^{+}\ell^{-}\ell^{\prime +}\ell^{\prime -}$ channel in proton-proton collisions at 13 TeV center-of-mass energy at the Large Hadron Collider are presented. The data correspond to 36.1 $\mathrm{fb}^{-1}$ of collisions collected by the ATLAS experiment in 2015 and 2016. Here $\ell$ and $\ell'$ stand for electrons or muons. Integrated and differential $ZZ \to \ell^{+}\ell^{-}\ell^{\prime +}\ell^{\prime -}$ cross sections with $Z \to \ell^+\ell^-$ candidate masses in the range of 66 GeV to 116 GeV are measured in a fiducial phase space corresponding to the detector acceptance and corrected for detector effects. The differential cross sections are presented in bins of twenty observables, including several that describe the jet activity. The integrated cross section is also extrapolated to a total phase space and to all Standard-Model decays of $Z$ bosons with mass between 66 GeV and 116 GeV, resulting in a value of $17.3 \pm 0.9$ [$\pm 0.6$ (stat.) $\pm 0.5$ (syst.) $\pm 0.6$ (lumi.)] pb. The measurements are found to be in good agreement with the Standard-Model predictions. A search for neutral triple gauge couplings is performed using the transverse momentum distribution of the leading $Z$-boson candidate. No evidence for such couplings is found and exclusion limits are set on their parameters.
Integrated fiducial cross sections. Fiducial phase space - At least 4 electrons, 4 muons, or 2 electrons and 2 muons forming two same-flavour opposite-charge dileptons (Z candidates) - Lepton pairing ambiguities are resolved by choosing the combination that results in the smaller value of the sum of |mll - mZ| for the two pairs, where mll is the mass of the dilepton system and mZ the Z boson pole mass - Lepton absolute pseudorapidity |eta| < 2.7 - Lepton transverse momentum pT > 5 GeV - The three leading-pT leptons satisfy pT > 20 GeV, 15 GeV, 10 GeV - Angular separation of any same-flavour (opposite-flavour) leptons DeltaR > 0.1 (0.2) - Both chosen dileptons have invariant mass between 66 GeV and 116 GeV - All possible same-flavour opposite-charge dileptons have mass > 5 GeV Details about the fiducial definition as well as all other aspects of the analysis can be found in the journal publication.
Differential fiducial cross section as function of the transverse momentum of the four-lepton system. Fiducial phase space - At least 4 electrons, 4 muons, or 2 electrons and 2 muons forming two same-flavour opposite-charge dileptons (Z candidates) - Lepton pairing ambiguities are resolved by choosing the combination that results in the smaller value of the sum of |mll - mZ| for the two pairs, where mll is the mass of the dilepton system and mZ the Z boson pole mass - Lepton absolute pseudorapidity |eta| < 2.7 - Lepton transverse momentum pT > 5 GeV - The three leading-pT leptons satisfy pT > 20 GeV, 15 GeV, 10 GeV - Angular separation of any same-flavour (opposite-flavour) leptons DeltaR > 0.1 (0.2) - Both chosen dileptons have invariant mass between 66 GeV and 116 GeV - All possible same-flavour opposite-charge dileptons have mass > 5 GeV Details about the fiducial definition as well as all other aspects of the analysis can be found in the journal publication.
Predicted background as function of the transverse momentum of the four-lepton system.
The production of $\Upsilon$ mesons in Pb-Pb collisions at a centre-of-mass energy per nucleon pair $\sqrt{s_{\rm NN}}$ = 5 TeV is measured with the muon spectrometer of the ALICE detector at the LHC. The yields as well as the nuclear modification factors are determined in the forward rapidity region $2.5<y<4.0$, as a function of rapidity, transverse momentum and collision centrality. The results show that the production of the $\Upsilon$(1S) meson is suppressed by a factor of about three with respect to the production in proton-proton collisions. For the first time, a significant signal for the $\Upsilon$(2S) meson is observed at forward rapidity, indicating a suppression stronger by about a factor 2-3 with respect to the ground state. The measurements are compared with transport, hydrodynamic, comover and statistical hadronisation model calculations.
Rapidity-differential yield of $\Upsilon(1\mathrm{S}) \rightarrow \mu^{+}\mu^{-}$ divided by the average nuclear overlap function $\langle T_{\mathrm{AA}} \rangle$ for the 0–90% centrality interval ($\langle T_{\mathrm{AA}} \rangle$ = 6.28 $\pm$ 0.06 mb$^{-1}$).
Rapidity-differential yield of $\Upsilon(2\mathrm{S}) \rightarrow \mu^{+}\mu^{-}$ divided by the average nuclear overlap function $\langle T_{\mathrm{AA}} \rangle$ for the 0–90% centrality interval ($\langle T_{\mathrm{AA}} \rangle$ = 6.28 $\pm$ 0.06 mb$^{-1}$).
$p_{\mathrm{T}}$-differential yield of $\Upsilon(1\mathrm{S}) \rightarrow \mu^{+}\mu^{-}$ divided by the average nuclear overlap function $\langle T_{\mathrm{AA}} \rangle$ for the 0–90% centrality interval ($\langle T_{\mathrm{AA}} \rangle$ = 6.28 $\pm$ 0.06 mb$^{-1}$).
The polarizations of the Y(1S), Y(2S), and Y(3S) mesons are measured as a function of the charged particle multiplicity in proton-proton collisions at sqrt(s) = 7 TeV. The measurements are performed with a dimuon data sample collected in 2011 by the CMS experiment, corresponding to an integrated luminosity of 4.9 inverse femtobarns. The results are extracted from the dimuon decay angular distributions, in two ranges of Y(nS) transverse momentum (10-15 and 15-35 GeV), and in the rapidity interval abs(y) < 1.2. The results do not show significant changes from low- to high-multiplicity pp collisions, although large uncertainties preclude definite statements in the Y(2S) and Y(3S) cases.
$\Upsilon$(nS) polarization parameter $\lambda_\vartheta$ in the HX frame for $p_T$ of 10 to 15 GeV. The global uncertainties, independent of state and $N_{ch}$ bin, are also indicated.
$\Upsilon$(nS) polarization parameter $\lambda_\varphi$ in the HX frame for $p_T$ of 10 to 15 GeV. The global uncertainties, independent of state and $N_{ch}$ bin, are also indicated.
$\Upsilon$(nS) polarization parameter $\lambda_{\vartheta\varphi}$ in the HX frame for $p_T$ of 10 to 15 GeV. The global uncertainties, independent of state and $N_{ch}$ bin, are also indicated.
The production of $\mathrm{K}^{*}(\mathrm{892})^{0}$ and $\mathrm{\phi(1020)}$ resonances has been measured in p-Pb collisions at $\sqrt{s_{\rm NN}}$ = 8.16 TeV using the ALICE detector. Resonances are reconstructed via their hadronic decay channels in the rapidity interval $-$0.5 $<$$y$$<$ 0 and the transverse momentum spectra are measured for various multiplicity classes up to $p_{\rm T}$ = 20 GeV/$c$ for $\mathrm{K}^{*}(\mathrm{892})^{0}$ and $p_{\rm T}$ = 16 GeV/$c$ for $\mathrm{\phi(1020)}$. The $p_{\rm T}$ -integrated yields and mean transverse momenta are reported and compared with previous results in pp, p-Pb and Pb-Pb collisions. The $x_{\mathrm{T}}$ scaling for $\mathrm{K}^{*}(\mathrm{892})^{0}$ and $\mathrm{\phi(1020)}$ resonance production is newly tested in p-Pb collisions and found to hold in the high-$p_{\rm T}$ region at LHC energies. The nuclear modification factors ($R_{\rm pPb}$) as a function of $p_{\rm T}$ for $\mathrm{K}^{*0}$ and $\mathrm{\phi}$ at $\sqrt{s_{NN}}$ = 8.16 TeV are presented along with the new $R_{\rm pPb}$ measurements of $\mathrm{K}^{*0}$, $\mathrm{\phi}$ , $\Xi$, and $\Omega$ at $\sqrt{s_{\rm NN}}$ = 5.02 TeV. At intermediate $p_{\rm T}$ (2-8 GeV/$c$), $R_{\rm pPb}$ of $\Xi$, $\Omega$ show a Cronin-like enhancement, while $\mathrm{K}^{*0}$ and $\mathrm{\phi}$ show no or little nuclear modification. At high $p_{\rm T}$ ($>$ 8 GeV/$c$), the $R_{\rm pPb}$ values of all hadrons are consistent with unity within uncertainties. The $R_{\rm pPb}$ of $\mathrm{K}^{*}(\mathrm{892})^{0}$ and $\mathrm{\phi(1020)}$ at $\sqrt{s_{\rm NN}}$ = 8.16 and 5.02 TeV show no significant energy dependence.
$p_{\mathrm T}$-differential yield of $\frac{\mathrm{K^{*0}} + \overline{\mathrm{K^{*0}}}}{2}$ in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}~=~$8.16 TeV (NSD).
$p_{\mathrm T}$-differential yield of $\frac{\mathrm{K^{*0}} + \overline{\mathrm{K^{*0}}}}{2}$ in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}~=~$8.16 TeV (Multiplicity class 0-5%).
$p_{\mathrm T}$-differential yield of $\frac{\mathrm{K^{*0}} + \overline{\mathrm{K^{*0}}}}{2}$ in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}~=~$8.16 TeV (Multiplicity class 5-10%).
The PHENIX experiment has measured $\phi$ meson production in $d$$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV using the dimuon and dielectron decay channels. The $\phi$ meson is measured in the forward (backward) $d$-going (Au-going) direction, $1.2<y<2.2$ ($-2.2<y<-1.2$) in the transverse-momentum ($p_T$) range from 1--7 GeV/$c$, and at midrapidity $|y|<0.35$ in the $p_T$ range below 7 GeV/$c$. The $\phi$ meson invariant yields and nuclear-modification factors as a function of $p_T$, rapidity, and centrality are reported. An enhancement of $\phi$ meson production is observed in the Au-going direction, while suppression is seen in the $d$-going direction, and no modification is observed at midrapidity relative to the yield in $p$$+$$p$ collisions scaled by the number of binary collisions. Similar behavior was previously observed for inclusive charged hadrons and open heavy flavor indicating similar cold-nuclear-matter effects.
Invariant yields of $\phi$ meson production as a function of $p_T$ at different $d$+Au centrality classes. Type B represents uncertainties that are correlated from point to point.
Invariant yields of $\phi$ meson production as a function of $p_T$ at different $d$+Au centrality classes. Type B represents uncertainties that are correlated from point to point.
Invariant yields of $\phi$ meson production as a function of $p_T$ at different $d$+Au centrality classes. Type B represents uncertainties that are correlated from point to point.
The PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC) has measured $\phi$ meson production and its nuclear modification in asymmetric Cu$+$Au heavy-ion collisions at $\sqrt{s_{NN}}=200$ GeV at both forward Cu-going direction ($1.2<y<2.2$) and backward Au-going direction ($-2.2<y<-1.2$), rapidities. The measurements are performed via the dimuon decay channel and reported as a function of the number of participating nucleons, rapidity, and transverse momentum. In the most central events, 0\%--20\% centrality, the $\phi$ meson yield integrated over $1<p_T<5$ GeV/$c$ prefers a smaller value, which means a larger nuclear modification, in the Cu-going direction compared to the Au-going direction. Additionally, the nuclear-modification factor in Cu$+$Au collisions averaged over all centrality is measured to be similar to the previous PHENIX result in $d$$+$Au collisions for these rapidities.
Invariant yield as a function of the number of participating nucleons for 1.2 < $|y|$ < 2.2 and 1 < $p_T$ < 5 GeV/$c$. Type A represents uncertainties that are uncorrelated from point to point, Type B represents uncertainties that are correlated from point to point, and Type C represents uncertainties in the overall normalization.
Invariant yield as a function of transverse momentum for 1.2 < $|y|$ < 2.2 and 0%–93% centrality. Type A represents uncertainties that are uncorrelated from point to point, Type B represents uncertainties that are correlated from point to point, and Type C represents uncertainties in the overall normalization.
Invariant yield as a function of rapidity for 1 < $p_T$ < 5 GeV/$c$ and 0%–93% centrality. Type A represents uncertainties that are uncorrelated from point to point, Type B represents uncertainties that are correlated from point to point, and Type C represents uncertainties in the overall normalization.
The prompt production of the charm baryon $\rm \Lambda_{c}^{+}$ and the $\rm \Lambda_{c}^{+}/\mathrm {D^0}$ production ratios were measured at midrapidity with the ALICE detector in pp and p-Pb collisions at $\sqrt{s_\mathrm{NN}} = 5.02$TeV. These new measurements show a clear decrease of the $\rm \Lambda_{c}^{+}/\mathrm {D^0}$ ratio with increasing transverse momentum ($p_{\rm T}$) in both collision systems in the range $2<p_{\rm T}<12$ GeV/$c$, exhibiting similarities with the light-flavour baryon-to-meson ratios ${\rm p}/\pi$ and $\Lambda/\mathrm {K^0_S}$. At low $p_{\rm T}$, predictions that include additional colour-reconnection mechanisms beyond the leading-colour approximation; assume the existence of additional higher-mass charm-baryon states; or include hadronisation via coalescence can describe the data, while predictions driven by charm-quark fragmentation processes measured in $\mathrm {e^+e^-}$ and $\mathrm {e^-p}$ collisions significantly underestimate the data. The results presented in this letter provide significant evidence that the established assumption of universality (colliding-system independence) of parton-to-hadron fragmentation is not sufficient to describe charm-baryon production in hadronic collisions at LHC energies.
Prompt $\Lambda_{\rm {c}}^{+}$ baryon $p_{\rm {T}}$-differential cross section in pp collisions at $\sqrt{s} = 5.02$ TeV in the rapidity interval $|y|<0.5$.
Prompt $\Lambda_{\rm {c}}^{+}$ baryon $p_{\rm {T}}$-differential cross section in p-Pb collisions at $\sqrt{s_{\rm {NN}}} = 5.02$ TeV in the rapidity interval $-0.96 \lt y \lt 0.04$.
The nuclear modification factor $R_\mathrm{pPb}$ of prompt $\Lambda_{\rm {c}}^{+}$ baryons in p-Pb collisions at $\sqrt{s_{\rm {NN}}} = 5.02$ TeV in the rapidity interval $ -0.96\lt y \lt 0.04$.
We report on the measurement of $\rm{J}/\psi$ production in the dielectron channel at mid-rapidity (|y|<1) in p+p and d+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV from the STAR experiment at the Relativistic Heavy Ion Collider. The transverse momentum $p_{T}$ spectra in p+p for $p_{T}$ < 4 GeV/c and d+Au collisions for $p_{T}$ < 3 GeV/c are presented. These measurements extend the STAR coverage for $\rm{J}/\psi$ production in p+p collisions to low $p_{T}$. The $<p_{T}^{2}>$ from the measured $\rm{J}/\psi$ invariant cross section in p+p and d+Au collisions are evaluated and compared to similar measurements at other collision energies. The nuclear modification factor for $\rm{J}/\psi$ is extracted as a function of $p_{T}$ and collision centrality in d+Au and compared to model calculations using the modified nuclear Parton Distribution Function and a final-state $\rm{J}/\psi$ nuclear absorption cross section.
The mean square of $p_T$.
Nuclear absorption cross section.
The nuclear modicifation factor vs. $p_T$ for $J\psi$ with |y| < 1 in 0-100 percent central d+Au collisions.
The measurement of the production of ${\rm f}_{0}(980)$ in inelastic pp collisions at $\sqrt{s} = 5.02$ TeV is presented. This is the first reported measurement of inclusive ${\rm f}_{0}(980)$ yield at LHC energies. The production is measured at midrapidity, $|y| < 0.5$, in a wide transverse momentum range, $0 < p_{\rm T} < 16$ GeV/$c$, by reconstructing the resonance in the ${\rm f}_{0}(980) \rightarrow \pi^{+}\pi^{-}$ hadronic decay channel using the ALICE detector. The $p_{\rm T}$-differential yields are compared to those of pions, protons and $\phi$ mesons as well as to predictions from the HERWIG 7.2 QCD-inspired Monte Carlo event generator and calculations from a coalescence model that uses the AMPT model as an input. The ratio of the $p_{\rm T}$-integrated yield of ${\rm f}_{0}(980)$ relative to pions is compared to measurements in ${\rm e}^{+}{\rm e}^{-}$ and pp collisions at lower energies and predictions from statistical hadronisation models and HERWIG 7.2. A mild collision energy dependence of the ${\rm f}_{0}(980)$ to pion production is observed in pp collisions from SPS to LHC energies. All considered models underpredict the $p_{\rm T}$-integrated $2{\rm f}_{0}(980)/(\pi^{+}+\pi^{-})$ ratio. The prediction from the canonical statistical hadronisation model assuming a zero total strangeness content of ${\rm f}_{0}(980)$ is consistent with the data within 1.9$\sigma$ and is the closest to the data. The results provide an essential reference for future measurements of the particle yield and nuclear modification in p$-$Pb and Pb$-$Pb collisions, which have been proposed to be instrumental to probe the elusive nature and quark composition of the ${\rm f}_{0}(980)$ scalar meson.
$p_{\rm T}$-differential yields of $f_{0}(980)$ at midrapidity in the inelastic pp collisions at $\sqrt(s)$ = 5.02 TeV. The uncertainty 'syst' indicates the total systematic uncertainty and 'stat' indicates the statistical uncertainty. The branching ratio correction amounts to BR = (46 $\pm$ 6)% [ Phys. Rev. Lett. 111 no. 6, (2013) 062001] assuming dominance of $\pi\pi$ and KK channel has been applied to the $p_{\rm T}$-differential yields of $f_{0}(980)$. The normalisation and branching ratio relative uncertainties on the yields are independent of $p_{\rm{T}}$ and amount to 2.5% and 13%, respectively and therefore not included in the $p_{\rm T}$-differential yields of $f_{0}(980)$.
$p_{\rm T}$-integrated yield of $f_{0}(980)$, dN/dy at midrapidity as a function of $\langle {\rm d}N_{\rm ch}/{\rm d}\eta \rangle$. The uncertainty 'syst' indicates the total systematic uncertainty on the measurement. The branching ratio correction amounts to BR = (46 $\pm$ 6)% [ Phys. Rev. Lett. 111 no. 6, (2013) 062001] assuming dominance of $\pi\pi$ and KK channel has been applied to the $p_{\rm T}$-differential yields of $f_{0}(980)$. Here, the branching ratio relative uncertainty (13%) for $f_{0}(980)$ is not included.
mean-$p_{\rm{T}}$ of $f_{0}(980)$, (<$p_{\rm{T}}$>) at midrapidity as a function of $\langle {\rm d}N_{\rm ch}/{\rm d}\eta \rangle$. The uncertainty 'syst' indicates the total systematic uncertainty on the measurement.
We have measured the partial width and forward-backward charge asymmetry for the reaction e + e - →Z 0 →μ + μ - (γ). We obtain a partial width Γ μμ of 83.3±1.3(stat)±0.9(sys) MeV and the following values for the vector and axial vector couplings: g v =−0.062 −0.015 +0.020 and g A =−0.497 −0.005 +0.005 . From our measurement of the partial width and the mass of the Z 0 boson we determine the effective electroweak mixing angle, sin 2 θ w =0.232±0.005, and the neutral current coupling strength parameter, ϱ =0.998±0.016.
No description provided.
Forward backward charge asymmetry.
No description provided.
We have measured the partial widths for the three reactions e + e − → Z 0 → e + e − , μ + μ − , τ + τ − . The results are Γ ee = 84.3±1.3 MeV, √ Γ ee Γ μμ =83.9±1.4 MeV, and √ Γ ee Γ ττ =83.9±1.4 MeV, where the errors are statistical. The systematic errors are estimated to be 1.0 MeV, 0.9 MeV, and 1.4 MeV, respectively. We perform a simultaneous fit to the cross sections for the e + e − →e + e − , μ + μ − , and τ + τ − data, the differential cross section as a function of polar angle for the electron data, and the forward- backward asymmetry for the muon data. We obtain the leptonic partial with Γ ℓℓ =84.0±0.9 (stat.) MeV. The systematic error is estimated to be 0.8 MeV. Also, we obtain the axial-vector and vector weak coupling constants of charged leptons, g A =−0.500±0.003 and g ν =−0.064 −0.013 +0.017 .
Cross section from 1990 data.
Visible cross section obtained using the cuts required by Method I (see text of paper). (1989 and 1990 data).
Visible cross section obtained using the cuts required by Method II (see text of paper). (1989 and 1990 data). RE = E+ E- --> E+ E- (GAMMA).
We report the results of first physics runs of the L3 detector at LEP. Based on 2538 hadron events, we determined the mass m z 0 and the width Γ z 0 of the intermediate vector boson Z 0 to be m z 0 =91.132±0.057 GeV (not including the 46 MeV LEP machine energy uncertainty) and Γ z 0 =2.588±0.137 GeV. We also determined Γ invisible =0.567±0.080 GeV, corresponding to 3.42±0.48 number of neutrino flavors. We also measured the muon pair cross section and determined the branching ratio Γ μμ = Γ h =0.056±0.006. The partial width of Z 0 →e + e − is Γ ee =88±9±7 MeV.
No description provided.
Using the DASP detector at the DESY storage ring DORIS we have continued measuring e + e − annihilations near and on the ϒ(9.46) resonance. From the cross sections for e + e − → μ + μ − and e + e − → hadrons we obtain a μ + μ − branching ratio for the ϒ(9.46) of (2.9 ± 1.3 ± 0.5) %, a leptonic width г ee = (1.35 ± 0.11 ± 0.22) keV and a total width of (47 −15 +37 keV.
VISIBLE HADRONIC CROSS SECTION. PEAK VALUE AT UPSILON IS 10.1 +- 0.7 NB.
No description provided.
The L3 detector at LEP has been used to determine the number of light neutrino families by measuring the cross section of single photon even in e + e − collisions at energies near the Z 0 resonance. We have observed 61 single photon candidates with more than 1.5 GeV of deposited energy in the barrel electromagnetic calorimeter, for a total integrated luminosity of 3.0 pb −1 . From a likelihood fir to the single photon cross sections, we determin N ν =3.24 ± 0.46 ( statistical ) ±0.22 ( systematic ).
Corrected single photon cross sections. Errors represent 68 pct CL intervals and take into account the background fluctuations.
The Beijing Spectrometer (BES) experiment has observed purely leptonic decays of the Ds meson in the reaction e+e−→Ds+Ds− at a c.m. energy of 4.03 GeV. Three events are observed in which one Ds decays hadronically to φπ, K¯*0K, or K¯0K, and the other decays leptonically to μνμ or τντ. With the assumption of μ−τ universality, values of the branching fraction, B(Ds→μνμ)=(1.5−0.6−0.2+1.3+0.3)%, and the Ds pseudoscalar decay constant, fDs=(4.3−1.3−0.4+1.5+0.4)×102 MeV, are obtained.
No description provided.
In this table CONST is the pseudoscalar decay constant, f_[D/S].
The reaction γγ → ϱ + ϱ − → π + π − π 0 π 0 has been studied with the ARGUS detector at the e + e − storage ring DORIS II at DESY. Near threshold, the cross section for this reaction is about four times smaller than for the reaction γγ → ϱ 0 ϱ 0 .
Data read from graph.
Data read from graph.
Data read from graph.
Cross sections for inclusive π0 production at large transverse momentum pT were measured in π−p, π+p, and pp collisions at 300 GeV/c. The cross-section ratio σ(π−p→π0X)/σ(π+p→π0X) was found to be consistent with unity in the pT region of 1 to 5 GeV/c. The cross-section ratio σ(π+p→π0X)/σ(pp→π0X) however is growing with increasing pT and increasing π0 c.m.-system rapidity in agreement with parton-model expectations, where the partons in the pions have on average higher momenta than in the proton.
THERE IS ALSO A 1 PCT UNCERTAINTY IN THE PT SCALE AND A 7 PCT UNCERTAINTY IN THE NORMALISATION.
A study of the fragmentation properties of charm and bottom quarks intoD mesons is presented. From 263 700Z0 hadronic decays collected in 1991 with the DELPHI detector at the LEP collider,D0,D+ andD*+ are reconstructed in the modesK−π+,K−π+K+ andD0π+ followed byD0→K−π+, respectively. The fractional decay widths\(\Gamma {{(Z^0\to {D \mathord{\left/ {\vphantom {D {\bar D}}} \right. \kern-\nulldelimiterspace} {\bar D}}X)} \mathord{\left/ {\vphantom {{(Z^0\to {D \mathord{\left/ {\vphantom {D {\bar D}}} \right. \kern-\nulldelimiterspace} {\bar D}}X)} {\Gamma _h }}} \right. \kern-\nulldelimiterspace} {\Gamma _h }}\) are determined, and first results are presented for the production ofD mesons from\(c\bar c\) and\(b\bar b\) events separately. The average energy fraction ofD*± in charm quark fragmentation is found to be 〈XE(D*)〉c=0.487±0.015 (stat)±0.005 (sys.). Assuming that the fraction ofDs and charm-baryons produced at LEP is similar to that around 10 GeV, theZ0 partial width into charm quark pairs is determined to beΓc/Γh=0.187±0.031 (stat)±0.023 (sys). The probability for ab quark to fragment into\(\bar B_s \) orb-baryons is inferred to be 0.268±0.094 (stat)±0.100 (sys) from the measured probability that it fragments into a\(\bar B^0 \) orB−.
Using full data sample.
Using full data sample with proper time > 1 ps to enrich (b bbar) content.
Data with Delta(L) > 1.
Cross sections for inclusive direct photon production in π−p, π+p, and pp collisions at 300 GeV/c are measured at transverse momenta pT up to 7 GeV/c (xT=0.6). For π−p→γX also the rapidity distribution is presented. The cross-section ratio σ(π−p→γX)/σ(π+p→γX) is found to be 1 at pT=4 GeV/c and rises with increasing pT. This observation signals the occurrence of valence-quark–antiquark annihilation. The results are in good agreement with QCD predictions.
THERE IS ALSO A 1 PCT UNCERTAINTY IN THE PT SCALE AND A 7 PCT UNCERTAINTY IN THE NORMALISATION.
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