A measurement is presented, using data taken with the H1 detector at HERA, of the contribution of diffractive interactions to deep-inelastic electron-proton scattering. The diffractive contribution to the proton structure function is evaluated as a function of the appropriate deep-inelastic scattering variables using a class of deep-inelastic ep scattering events with no hadronic energy flow in an interval of pseudo-rapidity adjacent to the proton beam direction. The dependence of this contribution on x-pomeron is consistent with both a diffractive interpretation and a factorisable ep diffractive cross section. A first measurement of the deep-inelastic structure of the pomeron in the form of a factorised structure function is presented. This structure function is observed to be consistent with scale invariance.
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The $Q~{2}$ dependence and the total cross sections for charged and neutral current processes are measured in $e~{\pm}p$ reactions for transverse momenta of the outgoing lepton larger than 25 GeV. Comparable size of cross sections for the neutral current process and for the weak charged current process are observed above $Q~2\approx5000$GeV$~2$. Using the shape and magnitude of the charged current cross section we determine a propagator mass of $m_{W} = 84\ ~{+10}_{-7}$ GeV.
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Total cross-section for E-P events.
A measurement of the proton structure function F 2 ( x , Q 2 ) is presented with about 1000 neutral current deep inelastic scattering events for Bjorken x in the range x ⋍ 10 −2 – 10 −4 and Q 2 > 5 GeV 2 . The measurement is based on an integrated luminosity of 22.5 nb −1 recorded by the H1 detector in the first year of HERA operation. The structure function F 2 ( x , Q 2 ) shows a significant rise with decreasing x .
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Inclusive e\pmp single and double differential cross sections for neutral and charged current deep inelastic scattering processes are measured with the H1 detector at HERA. The data were taken at a centre-of-mass energy of \surds = 319GeV with a total integrated luminosity of 333.7 pb-1 shared between two lepton beam charges and two longitudinal lepton polarisation modes. The differential cross sections are measured in the range of negative fourmomentum transfer squared, Q2, between 60 and 50 000GeV2, and Bjorken x between 0.0008 and 0.65. The measurements are combined with earlier published unpolarised H1 data to improve statistical precision and used to determine the structure function xF_3^gammaZ. A measurement of the neutral current parity violating structure function F_2^gammaZ is presented for the first time. The polarisation dependence of the charged current total cross section is also measured. The new measurements are well described by a next-to-leading order QCD fit based on all published H1 inclusive cross section data which are used to extract the parton distribution functions of the proton.
The Neutral Current Reduced Cross Section for E- P interactions with a beam polarisation of -25.8 % for Q^2 values of 120, 150, 200, 250 and 300 GeV^2.
The Neutral Current Reduced Cross Section for E- P interactions with a beam polarisation of -25.8 % for Q^2 values of 400, 500, 650, 800 and 1000 GeV^2.
The Neutral Current Reduced Cross Section for E- P interactions with a beam polarisation of -25.8 % for Q^2 values of 1200, 1500, 2000, 3000 and 5000 GeV^2.
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.
We have measured the ratio g1pF1p over the range 0.029<x<0.8 and 1.3<Q2<10 (GeV/c)2 using deep-inelastic scattering of polarized electrons from polarized ammonia. An evaluation of the integral ∫01g1p(x, Q2)dx at fixed Q2=3 (GeV/c)2 yields 0.127±0.004(stat)±0.010(syst), in agreement with previous experiments, but well below the Ellis-Jaffe sum rule prediction of 0.160±0.006. In the quark-parton model, this implies Δq=0.27±0.10.
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Values of G1 computed assuming G1/F1 is independent of Q**2 and using a fixed Q**2 of 3 GeV**2.
Using 13.5-GeV beams at Stanford Linear Accelerator Center, we have compared electron and positron inelastic scattering over the range 1.2<|q2|<3.3 (GeV/c)2, 2<ν<9.5 GeV for the four-momentum and energy transfers, respectively. We find the ratio of the cross sections to be e+e−=1.0027±0.0035 (including statistical and systematic effects), with no significant dependence on q2 or ν. This result has appreciably smaller errors than previous attempts to find two-photon-exchange effects in electron or muon scattering.
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A combination is presented of all inclusive deep inelastic cross sections previously published by the H1 and ZEUS collaborations at HERA for neutral and charged current $e^{\pm}p$ scattering for zero beam polarisation. The data were taken at proton beam energies of 920, 820, 575 and 460 GeV and an electron beam energy of 27.5 GeV. The data correspond to an integrated luminosity of about 1 fb$^{-1}$ and span six orders of magnitude in negative four-momentum-transfer squared, $Q^2$, and Bjorken $x$. The correlations of the systematic uncertainties were evaluated and taken into account for the combination. The combined cross sections were input to QCD analyses at leading order, next-to-leading order and at next-to-next-to-leading order, providing a new set of parton distribution functions, called HERAPDF2.0. In addition to the experimental uncertainties, model and parameterisation uncertainties were assessed for these parton distribution functions. Variants of HERAPDF2.0 with an alternative gluon parameterisation, HERAPDF2.0AG, and using fixed-flavour-number schemes, HERAPDF2.0FF, are presented. The analysis was extended by including HERA data on charm and jet production, resulting in the variant HERAPDF2.0Jets. The inclusion of jet-production cross sections made a simultaneous determination of these parton distributions and the strong coupling constant possible, resulting in $\alpha_s(M_Z)=0.1183 \pm 0.0009 {\rm(exp)} \pm 0.0005{\rm (model/parameterisation)} \pm 0.0012{\rm (hadronisation)} ^{+0.0037}_{-0.0030}{\rm (scale)}$. An extraction of $xF_3^{\gamma Z}$ and results on electroweak unification and scaling violations are also presented.
HERA combined reduced cross sections $\sigma_{r,\rm NC}^{+}$ for NC $e^{+}p$ scattering at $\sqrt{s} = 318$ GeV; $\delta_{\rm stat}$, $\delta_{\rm uncor}$ and $\delta_{\rm cor}$ represent the statistical, uncorrelated systematic and correlated systematic uncertainties, respectively; $\delta_{\rm rel}$, $\delta_{\gamma p}$, $\delta_{\rm had}$ and $\delta_{1}$ to $\delta_{4}$ are the correlated sources of uncertainties arising from the combination procedure. The uncertainties are quoted in percent relative to $\sigma_{r,\rm NC}^{+}$.
HERA combined reduced cross sections $\sigma_{r,\rm NC}^{+}$ for NC $e^{+}p$ scattering at $\sqrt{s} = 300$ GeV; $\delta_{\rm stat}$, $\delta_{\rm uncor}$ and $\delta_{\rm cor}$ represent the statistical, uncorrelated systematic and correlated systematic uncertainties, respectively; $\delta_{\rm rel}$, $\delta_{\gamma p}$, $\delta_{\rm had}$ and $\delta_{1}$ to $\delta_{4}$ are the correlated sources of uncertainties arising from the combination procedure. The uncertainties are quoted in percent relative to $\sigma_{r,\rm NC}^{+}$.
HERA combined reduced cross sections $\sigma_{r,\rm NC}^{+}$ for NC $e^{+}p$ scattering at $\sqrt{s} = 251$ GeV; $\delta_{\rm stat}$, $\delta_{\rm uncor}$ and $\delta_{\rm cor}$ represent the statistical, uncorrelated systematic and correlated systematic uncertainties, respectively; $\delta_{\rm rel}$, $\delta_{\gamma p}$, $\delta_{\rm had}$ and $\delta_{1}$ to $\delta_{4}$ are the correlated sources of uncertainties arising from the combination procedure. The uncertainties are quoted in percent relative to $\sigma_{r,\rm NC}^{+}$.
The ratio g1/F1 has been measured over the range 0.03<x<0.6 and 0.3<Q2<10 (GeV/c)2 using deep-inelastic scattering of polarized electrons from polarized protons and deuterons. We find g1/F1 to be consistent with no Q2-dependence at fixed x in the deep-inelastic region Q~2>1 (GeV/c)2. A trend is observed for g1/F1 to decrease at lower Q2. Fits to world data with and without a possible Q2-dependence in g1/F1 are in agreement with the Bjorken sum rule, but Delta_q is substantially less than the quark-parton model expectation.
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This paper presents our first measurement of the F 2 structure function in neutral-current, deep inelastic scattering using the ZEUS detector at HERA, the ep colliding beam facility at DESY. The data correspond to an integrated luminosity of 24.7 nb −1 . Results are presented for data in range of Q 2 from 10 GeV 2 to 4700 GeV 2 and Bjorken x down to 3.0 × 10 −4 . The F 2 structure function increases rapidly as x decreases.
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