The e^+p charged-current deep inelastic scattering cross sections, $d\sigma/dQ^2$ for Q^2 between 200 and 60000 GeV^2, and $d\sigma/dx$ and $d\sigma/dy$ for Q^2 > 200 GeV^2, have been measured with the ZEUS detector at HERA. A data sample of 47.7 pb^-1, collected at a center-of-mass energy of 300 GeV, has been used. The cross section $d\sigma/dQ^2$ falls by a factor of about 50000 as Q^2 increases from 280 to 30000 GeV^2. The double differential cross section $d^2\sigma/dxdQ^2$ has also been measured. A comparison between the data and Standard Model (SM) predictions shows that contributions from antiquarks ($\bar{u}$ and $\bar{c}$) and quarks (d and s) are both required by the data. The predictions of the SM give a good description of the full body of the data presented here. A comparison of the charged-current cross section $d\sigma/dQ^2$ with the recent ZEUS results for neutral-current scattering shows that the weak and electromagnetic forces have similar strengths for Q^2 above $M^2_W, M^2_Z$. A fit to the data for $d\sigma/dQ^2$ with the Fermi constant $G_F$ and $M_W$ as free parameters yields $G_F = (1.171 \pm 0.034 (stat.) ^{+0.026}_{-0.032} (syst.) ^{+0.016}_{-0.015} (PDF)) \times 10^{-5} GeV^{-2}$ and $M_W = 80.8 ^{+4.9}_{-4.5} (stat.) ^{+5.0}_{-4.3} (syst.) ^{+1.4}_{-1.3} (PDF) GeV$. Results for $M_W$, where the propagator effect alone or the SM constraint between $G_F$ and $M_W$ have been considered, are also presented.
The differential cross section DSIG/DQ**2.
The differential cross section DSIG/DX.
The differential cross section DSIG/DY.
The production of D*+-(2010) mesons in deep inelastic scattering has been measured in the ZEUS detector at HERA using an integrated luminosity of 37 pb^-1. The decay channels D*+ -> D0 pi+(+c.c.), with D0 -> K- pi+ or D0 ->K- pi- pi+ pi+, have been used to identify the D mesons. The e+p cross section for inclusive D*+- production with 1<Q^2<600 GeV^2 and 0.02<y<0.7 is 8.31 +- 0.31(stat.) +0.30-0.50(syst.) nb in the kinematic region 1.5< pT(D*+-)<15 GeV and |eta(D*+-)|<1.5. Differential cross sections are consistent with a next-to-leading-order perturbative-QCD calculation when using charm-fragmentation models which take into account the interaction of the charm quark with the proton remnant. The observed cross section is extrapolated to the full kinematic region in pT(D*+-) and eta(D*+-) in order to determine the charm contribution, F^ccbar_2(x,Q^2), to the proton structure function. The ratio F^ccbar_2/F_2 rises from ~10% at Q^2 ~1.8 GeV^2 to ~30% at Q^2 ~130 GeV^2 for x values in the range 10^-4 to 10-3.
The measured cross section for D* production. The first is derived from theK2PI final state and the second from the K4PI final state.
The differential cross section w.r.t. Q**2 from the K2PI final state. The asymmetric errors are the quadratic sum of the statistical and systematic errors. The statistical errors are also shown separately.
The differential cross section w.r.t. X from the K2PI final state. The asymmetric errors are the quadratic sum of the statistical and systematic errors. The statistical errors are also shown separately.
Production of D*+/-(2010) mesons in diffractive deep inelastic scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 82 pb^{-1}. Diffractive events were identified by the presence of a large rapidity gap in the final state. Differential cross sections have been measured in the kinematic region 1.5 < Q^2 < 200 GeV^2, 0.02 < y < 0.7, x_{IP} < 0.035, beta < 0.8, p_T(D*+/-) > 1.5 GeV and |\eta(D*+/-)| < 1.5. The measured cross sections are compared to theoretical predictions. The results are presented in terms of the open-charm contribution to the diffractive proton structure function. The data demonstrate a strong sensitivity to the diffractive parton densities.
Total cross section for diffractive D*+- production in the stated kinematicregion.. The second DSYS uncertainty arises from the subtraction of the proton-dissociative background.
The differential cross section as a function of X(NAME=POMERON).
The differential cross section as a function of transverse momentum.
This paper presents measurements of D^{*\pm} production in deep inelastic scattering from collisions between 27.5 GeV positrons and 820 GeV protons. The data have been taken with the ZEUS detector at HERA. The decay channel $D^{*+}\to (D^0 \to K^- \pi^+) \pi^+ $ (+ c.c.) has been used in the study. The $e^+p$ cross section for inclusive D^{*\pm} production with $5<Q^2<100 GeV^2$ and $y<0.7$ is 5.3 \pms 1.0 \pms 0.8 nb in the kinematic region {$1.3<p_T(D^{*\pm})<9.0$ GeV and $| \eta(D^{*\pm}) |<1.5$}. Differential cross sections as functions of p_T(D^{*\pm}), $\eta(D^{*\pm}), W$ and $Q^2$ are compared with next-to-leading order QCD calculations based on the photon-gluon fusion production mechanism. After an extrapolation of the cross section to the full kinematic region in p_T(D^{*\pm}) and $\eta$(D^{*\pm}), the charm contribution $F_2^{c\bar{c}}(x,Q^2)$ to the proton structure function is determined for Bjorken $x$ between 2 $\cdot$ 10$^{-4}$ and 5 $\cdot$ 10$^{-3}$.
No description provided.
Integrated charm cross sections in two Q**2 regions.
Distribution of the fractional momentum of the D* in the gamma*-p system.
The e^+p neutral-current deep inelastic scattering differential cross-sections $d\sigma/dQ^2$, for Q^2 > 400 GeV^2, $d\sigma/dx$ and $d\sigma/dy$, for Q^2 > 400, 2500 and 10000 GeV^2, have been measured with the ZEUS detector at HERA. The data sample of 47.7 pb^-1 was collected at a center-of-mass energy of 300 GeV. The cross-section, $d\sigma/dQ^2$, falls by six orders of magnitude between Q^2 = 400 and 40000 GeV^2. The predictions of the Standard Model are in very good agreement with the data. Complementing the observations of time-like Z^0 contributions to fermion-antifermion annihilation, the data provide direct evidence for the presence of Z^0 exchange in the space-like region explored by deep inelastic scattering.
The differential cross section as a function of Q**2.
The differential cross section as a function of x, the Bjorken x variable.
The differential cross section as a function of x, the Bjorken x variable.
Deep inelastic $e~-p$ scattering has been studied in both the charged-current (CC) and neutral-current (NC) reactions at momentum transfers squared, $Q~2$, between 400 GeV$~2$ and the kinematic limit of 87500 GeV$~2$ using the ZEUS detector at the HERA $ep$ collider. The CC and NC total cross sections, the NC to CC cross section ratio, and the differential cross sections, $ d\sigma/dQ~2 $, are presented. For $Q~2 \simeq M_W~2$, where $M_W$ is the mass of the $W$ boson, the CC and NC cross sections have comparable magnitudes, demonstrating the equal strengths of the weak and electromagnetic interactions at high $Q~2$. The $Q~2$ dependence of the CC cross section determines the mass term in the CC propagator to be $M_{W} = 76 \pm 16 \pm 13$GeV.
Data requested from authors.
Neutral current cross sections.
Charged current cross sections.
None
Axis error includes +- 10/10 contribution.
Axis error includes +- 10/10 contribution.
Axis error includes +- 10/10 contribution.
The production rates and substructure of jets have been studied in charged current deep inelastic e+p scattering for Q**2>200 GeV**2 with the ZEUS detector at HERA using an integrated luminosity of 110.5 pb**-1. Inclusive jet cross sections are presented for jets with transverse energies E_T(jet) > 14 GeV and pseudorapidities in the range -1 < eta(jet) < 2. Dijet cross sections are presented for events with a jet having E_T(jet) > 14 GeV and a second jet having E_T(jet) > 5 GeV. Measurements of the mean subjet multiplicity, <n_sbj>, of the inclusive jet sample are presented. Predictions based on parton-shower Monte Carlo models and next-to-leading-order QCD calculations a re compared to the measurements. The value of alphas(M_Z), determined from <n_sbj> at y_cut=0.01 for jets with 25<E_T(jet)<119 GeV, is alphas(M_Z) = 0.1202 +-0.0052 (stat.) +0.0060-0.0019 (syst.) +0.0065-0.0053 (th.). The mean subjet multiplicity as a function of Q**2 is found to be consistent with that measured in NC DIS.
Inclusive jet cross section DSIG/DQ**2 for jets in the lab. frame. Data from the 1995-1997 sample.
Inclusive jet cross section DSIG/DQ**2 for jets in the lab. frame. Data from the 1999-2000 sample.
Inclusive jet cross section DSIG/DQ**2 for jets in the lab. frame. Data from the combined sample.
Inclusive production of $D^*(2010)$ mesons in deep inelastic scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 81.9 pb$^{-1}$. The decay channel $D^{* +}\to D^0 \pi^+ $ with $D^0\to K^-\pi^+$ and corresponding antiparticle decay were used to identify $D^*$ mesons. Differential $D^*$ cross sections with $1.5<Q^2<1000$ GeV$^2$ and $0.02<y<0.7$ in the kinematic region $1.5<p_T(D^*)<15$ GeV and $|\eta(D^*)|<1.5$ are compared to different QCD calculations incorporating different parameterisations of the parton densities in the proton. The data show sensitivity to the gluon distribution in the proton and are reasonably well described by next-to-leading-order QCD with the ZEUS NLO QCD fit used as the input parton density in the proton. The observed cross section is extrapolated to the full kinematic region in $p_T(D^*)$ and $\eta(D^*)$ in order to determine the open-charm contribution, $F_2^{\rm charm}(x,Q^2)$, to the proton structure function, $F_2$. Since, at low $Q^2$, the uncertainties of the data are comparable to those from the QCD fit, the measured differential cross sections in $y$ and $Q^2$ should be used in future fits to constrain the gluon density.
Overall total cross section. The second DSYS error is due to the uncertainty in the BR for D* and D0 decay.
Measured differential cross section as a function of Q**2.
Measured differential cross section as a function of X.
Cross sections for e^+p charged current deep inelastic scattering at a centre-of-mass energy of 318 GeV have been determined with an integrated luminosity of 60.9pb^-1 collected with the ZEUS detector at HERA. The differential cross sections dsigma/dQ^2, dsigma/dx and dsigma/dy for Q^2>200 GeV^2 are presented. In addition, d^2sigma/dxdQ^2 has been measured in the kinematic range 280 GeV^2 < Q^2 < 17000 GeV^2 and 0.008 < x < 0.42. The predictions of the Standard Model agree well with the measured cross sections. The mass of the W boson propagator is determined to be M_W=78.9 +/- 2.0 (stat.) +/- 1.8 (syst.) +2.0 -1.8 (PDF) GeV from a fit to dsigma/dQ^2. The chiral structure of the Standard Model is also investigated in terms of the (1-y)^2 dependence of the the double-differential cross section. The structure-function F_2^CC has been extracted by combining the measurements presented here with previous ZEUS results from e^-p scattering, extending the measurement obtained in a neutrino-nucleus scattering experiment to a significantly higher Q^2 region.
The total cross section for Q**2 > 200 GeV**2.
The differential cross section as a function of Q**2.
The differential cross section as a function of X.
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