Production of exclusive dijets in diffractive deep inelastic $e^\pm p$ scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 372 pb$^{-1}$. The measurement was performed for $\gamma^*-p$ centre-of-mass energies in the range $90 < W < 250$ GeV and for photon virtualities $Q^2 > 25$ GeV$^2$. Energy and transverse-energy flows around the jet axis are presented. The cross section is presented as a function of $\beta$ and $\phi$, where $\beta=x/x_{\rm I\!P}$, $x$ is the Bjorken variable and $x_{\rm I\!P}$ is the proton fractional longitudinal momentum loss. The angle $\phi$ is defined by the $\gamma^*-$dijet plane and the $\gamma^*-e^\pm$ plane in the rest frame of the diffractive final state. The $\phi$ cross section is measured in bins of $\beta$. The results are compared to predictions from models based on different assumptions about the nature of the diffractive exchange.
Differential cross-section $d\sigma/d\beta$ in the kinematic range: $Q^2 > 25 GeV^2$, $90 < W < 250 GeV^2$, $x_{\rm I\!P} < 0.01$, $M_X > 5 GeV$ and $p_{T,jet} > 2 GeV$. The contribution from proton dissociation was subtracted. The uncertainty of the subtraction determines the uncertainty of the normalisation also given in the table.
Differential cross-section $d\sigma/d\phi$ in the kinematic range: $Q^2 > 25 GeV^2$, $90 < W < 250 GeV$, $x_{\rm I\!P} < 0.01$, $M_X > 5 GeV$ and $p_{T,jet} > 2 GeV$. The contribution from proton dissociation was subtracted. The uncertainty of the subtraction determines the uncertainty of the normalisation given in the table.
Results of the fit to the cross-section $d\sigma/d\phi$ in bins of $\beta$. The fitted function is proportional to $(1+A \rm{cos}2\phi)$. The uncertainty includes both statistical and systematical contributions (see text of paper).
The normalized differential cross section for top quark pair (tt-bar) production is measured in pp collisions at a centre-of-mass energy of 8 TeV at the CERN LHC using the CMS detector in data corresponding to an integrated luminosity of 19.7 inverse femtobarns. The measurements are performed in the lepton + jets (e/mu + jets) and in the dilepton (e+e-, mu+mu-, and e+-mu-+) decay channels. The tt-bar cross section is measured as a function of the kinematic properties of the charged leptons, the jets associated to b quarks, the top quarks, and the tt-bar system. The data are compared with several predictions from perturbative quantum chromodynamics up to approximate next-to-next-to-leading-order precision. No significant deviations are observed relative to the standard model predictions.
Normalized differential tt cross section (from l+jets channel) as a function of the transverse momentum pt of the lepton. The results are presented at particle level in the fiducial phase space. The statistical and systematic uncertainties are added in quadrature to yield the total uncertainty.
Normalized differential tt cross section (from l+jets channel) as a function of the pseudo-rapidity of the lepton. The results are presented at particle level in the fiducial phase space. The statistical and systematic uncertainties are added in quadrature to yield the total uncertainty.
Normalized differential tt cross section (from l+jets channel) as a function of the transverse momentum pt(b-jet) of the b-jet. The results are presented at particle level in the fiducial phase space. The statistical and systematic uncertainties are added in quadrature to yield the total uncertainty.
We present measurements from the PHENIX experiment of large parity-violating single spin asymmetries of high transverse momentum electrons and positrons from $W^\pm/Z$ decays, produced in longitudinally polarized $p$$+$$p$ collisions at center of mass energies of $\sqrt{s}$=500 and 510~GeV. These asymmetries allow direct access to the anti-quark polarized parton distribution functions due to the parity-violating nature of the $W$-boson coupling to quarks and anti-quarks. The results presented are based on data collected in 2011, 2012, and 2013 with an integrated luminosity of 240 pb$^{-1}$, which exceeds previous PHENIX published results by a factor of more than 27. These high $Q^2$ data provide an important addition to our understanding of anti-quark parton helicity distribution functions.
Longitudinal single-spin asymmetries, $A_L$, for the 2011 and 2012 data sets (combined) spanning the entire $\eta$ range of PHENIX ($\left|\eta\right|<0.35$), for the 2013 data set separated into two $\eta$ bins, and for the combined 2011-2013 data sets.
Results are reported on a search for decays of a pseudoscalar A boson into a Z boson and a light scalar h boson, where the Z boson decays into a pair of oppositely-charged electrons or muons, and the h boson decays into b anti-b. The search is based on data from proton-proton collisions at a center-of-mass energy sqrt(s)=8 TeV collected with the CMS detector, corresponding to an integrated luminosity of 19.7 inverse femtobarns. The h boson is assumed to be the standard model-like Higgs boson with a mass of 125 GeV. With no evidence for signal, upper limits are obtained on the product of the production cross section and the branching fraction of the A boson in the Zh channel. Results are also interpreted in the context of two Higgs doublet models.
Observed and expected 95% CL upper limits on sigma A x B(A->Zh->llbb) as a function of mA in the narrow-width approximation, including statistical and systematic uncertainties.
Observed 95% CL upper limits on sigma A x B(A->Zh->llbb) as a function of mA and the A natural width Gamma.
Expected 95% CL upper limits on sigma A x B(A->Zh->llbb) as a function of mA and the A natural width Gamma.
We present a measurement of the Z boson differential cross section in rapidity and transverse momentum using a data sample of pp collision events at a centre-of-mass energy sqrt(s)=8 TeV, corresponding to an integrated luminosity of 19.7 inverse femtobarns. The Z boson is identified via its decay to a pair of muons. The measurement provides a precision test of quantum chromodynamics over a large region of phase space. In addition, due to the small experimental uncertainties in the measurement the data has the potential to constrain the gluon parton distribution function in the kinematic regime important for Higgs boson production via gluon fusion. The results agree with the next-to-next-to-leading-order predictions computed with the FEWZ program. The results are also compared to the commonly used leading-order MADGRAPH and next-to-leading-order POWHEG generators.
Measured double differential fiducial cross section normalised to the inclusive fiducial cross section. The uncertainty indicates the total experimental uncertainties (statistical and systematic added in quadrature).
Measured absolute double differential fiducial cross section. The uncertainty indicates the total experimental uncertainties (statistical and systematic added in quadrature).
Covariance matrix of total experimental uncertainties (statistical and systematic uncertainties added in quadrature) of double differential fiducial cross section normalised to the inclusive fiducial cross section. The bin index is PT_i + 10*y_j.
Measurements of the five most significant angular coefficients, A[0] through A[4], for Z bosons produced in pp collisions at $\sqrt{s}$ = 8 TeV and decaying to $\mu^+ \mu^-$ are presented as a function of the transverse momentum and rapidity of Z boson. The integrated luminosity of the dataset collected with the CMS detector at the LHC corresponds to 19.7 inverse femtobarns. These measurements provide comprehensive information about Z boson production mechanisms, and are compared to QCD predictions at leading order, next-to-leading order, and next-to-next-to-leading order in perturbation theory.
The five angular coefficients A0 to A4 and A0-A2 in bins of qT for |y| < 1.
The five angular coefficients A0 to A4 and A0-A2 in bins of qT for 1 < |y| < 2.1.
A search is presented for particle dark matter produced in association with a pair of top quarks in pp collisions at a centre-of-mass energy of sqrt(s) = 8 TeV. The data were collected with the CMS detector at the LHC and correspond to an integrated luminosity of 19.7 inverse femtobarns. This search requires the presence of one lepton, multiple jets, and large missing transverse energy. No excess of events is found above the SM expectation, and upper limits are derived on the production cross section. Interpreting the findings in the context of a scalar contact interaction between fermionic dark matter particles and top quarks, lower limits on the interaction scale are set. These limits are also interpreted in terms of the dark matter-nucleon scattering cross sections for the spin-independent scalar operator and they complement direct searches for dark matter particles in the low mass region.
Systematic uncertainties from various sources and their impact on the total background prediction.
Expected number of background events in the SR, expected number of signal events for a DM particle with the mass $M_{\chi}$ = 1 GeV, assuming an interaction scale $M_{*}$ = 100 GeV, and observed data. The statistical and systematic uncertainties are given on the expected yields.
Expected number of signal events in SR assuming an interaction scale $M_{*}$ = 100 GeV, signal efficiencies, and observed and expected limits at 90% CL on production cross sections for $\mathrm{pp \rightarrow t\bar{t} + \chi\bar{\chi}}$, for various DM particle masses.
A search for a heavy Higgs boson in the H to WW and H to ZZ decay channels is reported. The search is based upon proton-proton collision data samples corresponding to an integrated luminosity of up to 5.1 inverse femtobarns at sqrt(s) = 7 TeV and up to 19.7 inverse femtobarns at sqrt(s) = 8 TeV, recorded by the CMS experiment at the CERN LHC. Several final states of the H to WW and H to ZZ decays are analyzed. The combined upper limit at the 95% confidence level on the product of the cross section and branching fraction exclude a Higgs boson with standard model-like couplings and decays in the range 145 < m[H] < 1000 GeV. We also interpret the results in the context of an electroweak singlet extension of the standard model.
Upper limits at 95\% CL on the cross section for a heavy Higgs boson decaying to a pair of W bosons as a function of its mass and its width relative to a SM-like Higgs boson.
Upper limits at 95\% CL on the cross section for a heavy Higgs boson decaying to a pair of Z bosons as a function of its mass and its width relative to a SM-like Higgs boson.
Upper limits at 95% CL on the cross section for a heavy Higgs boson as a function of its mass and its width relative to a SM-like Higgs boson. Both, gluon-gluon fusion and VBF production processes are combined, assuming a SM-like ratio between the two.
H1 and ZEUS have published single-differential cross sections for inclusive D^{*\pm}-meson production in deep-inelastic ep scattering at HERA from their respective final data sets. These cross sections are combined in the common visible phase-space region of photon virtuality Q2 > 5 GeV2, electron inelasticity 0.02 < y < 0.7 and the D^{*\pm} meson's transverse momentum pT (D^*) > 1.5 GeV and pseudorapidity |eta(D^*)| < 1.5. The combination procedure takes into account all correlations, yielding significantly reduced experimental uncertainties. Double-differential cross sections d2s /dQ2dy are combined with earlier D^{*\pm} data, extending the kinematic range down to Q2 > 1.5 GeV2. Perturbative next-to-leadingorder QCD predictions are compared to the results.
The combined differential $D^{*\pm}$-production cross section as a function of $p_T(D^{*})$, with its uncorrelated and correlated uncertainties.
The combined differential $D^{*\pm}$-production cross section as a function of $\eta(D^{*})$, with its uncorrelated and correlated uncertainties.
The combined differential $D^{*\pm}$-production cross section as a function of $z(D^{*})$, with its uncorrelated and correlated uncertainties.
The first study of W boson production in pPb collisions is presented, for bosons decaying to a muon or electron, and a neutrino. The measurements are based on a data sample corresponding to an integrated luminosity of 34.6 inverse nanobarns at a nucleon-nucleon centre-of-mass energy of sqrt(s[NN]) = 5.02 TeV, collected by the CMS experiment. The W boson differential cross sections, lepton charge asymmetry, and forward-backward asymmetries are measured for leptons of transverse momentum exceeding 25 GeV, and as a function of the lepton pseudorapidity in the abs(eta[lab]) < 2.4 range. Deviations from the expectations based on currently available parton distribution functions are observed, showing the need for including W boson data in nuclear parton distribution global fits.
Lepton charge asymmetry, $(N_{\ell}^+ - N_{\ell}^-)/(N_{\ell}^+ + N_{\ell}^-)$ as a function of the lepton pseudorapidity.
Production cross section for $\textrm{pPb} \to W^+ + X \to \ell \nu + X$ for positively (top) and negatively (bottom) charged leptons of $p_T$ larger than 25 GeV$/c$, in nanobarns, as a function of the lepton pseudorapidity. Values are given first for muons and electrons separately, then combined. The global normalization uncertainty of 3.5\% is not included in the listed uncertainties.
Production cross section for $\textrm{pPb} \to W^- + X \to \ell \nu + X$ for positively (top) and negatively (bottom) charged leptons of $p_T$ larger than 25 GeV$/c$, in nanobarns, as a function of the lepton pseudorapidity. Values are given first for muons and electrons separately, then combined. The global normalization uncertainty of 3.5\% is not included in the listed uncertainties.
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