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(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image).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 ... 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... and span six orders of magnitude in negative four-momentum-transfer squared, ..., 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 ... An extraction of ... and results on electroweak unification and scaling violations are also presented.

Cross sections for elastic and proton-dissociative photoproduction of J / ψ mesons are measured with the H1 detector in positron-proton collisions at HERA. The data were collected at ep centre-of-mass energies and , corresponding to integrated luminosities of and , respectively. The cross sections are measured as a function of the photon-proton centre-of-mass energy in the range 25< W γp <110 GeV. Differential cross sections d σ /d t , where t is the squared four-momentum transfer at the proton vertex, are measured in the range | t |<1.2 GeV 2 for the elastic process and | t |<8 GeV 2 for proton dissociation. The results are compared to other measurements. The W γp and t -dependences are parametrised using phenomenological fits.

The strong coupling constant α s is determined from inclusive jet and dijet cross sections in neutral-current deep-inelastic ep scattering (DIS) measured at HERA by the H1 collaboration using next-to-next-to-leading order (NNLO) QCD predictions. The dependence of the NNLO predictions and of the resulting value of α s ( m Z ) at the Z -boson mass m Z are studied as a function of the choice of the renormalisation and factorisation scales. Using inclusive jet and dijet data together, the strong coupling constant is determined to be α s ( m Z ) = 0.1157 ( 20 ) exp ( 29 ) th . Complementary, α s ( m Z ) is determined together with parton distribution functions of the proton (PDFs) from jet and inclusive DIS data measured by the H1 experiment. The value α s ( m Z ) = 0.1142 ( 28 ) tot obtained is consistent with the determination from jet data alone. The impact of the jet data on the PDFs is studied. The running of the strong coupling is tested at different values of the renormalisation scale and the results are found to be in agreement with expectations.

A precision measurement of jet cross sections in neutral current deep-inelastic scattering for photon virtualities 5.5 < Q 2 < 80 GeV 2 and inelasticities 0.2 < y < 0.6 is presented, using data taken with the H1 detector at HERA, corresponding to an integrated luminosity of 290 pb - 1 . Double-differential inclusive jet, dijet and trijet cross sections are measured simultaneously and are presented as a function of jet transverse momentum observables and as a function of Q 2 . Jet cross sections normalised to the inclusive neutral current DIS cross section in the respective Q 2 -interval are also determined. Previous results of inclusive jet cross sections in the range 150 < Q 2 < 15 , 000 GeV 2 are extended to low transverse jet momenta 5 < P T jet < 7 GeV . The data are compared to predictions from perturbative QCD in next-to-leading order in the strong coupling, in approximate next-to-next-to-leading order and in full next-to-next-to-leading order. Using also the recently published H1 jet data at high values of Q 2 , the strong coupling constant α s ( M Z ) is determined in next-to-leading order.

The H1 Collaboration at HERA reports the first measurement of groomed event shape observables in deep inelastic electron-proton scattering (DIS) at s = 319 GeV, using data recorded between the years 2003 and 2007 with an integrated luminosity of 351 pb - 1 . Event shapes provide incisive probes of perturbative and non-perturbative QCD. Grooming techniques have been used for jet measurements in hadronic collisions; this paper presents the first application of grooming to DIS data. The analysis is carried out in the Breit frame, utilizing the novel Centauro jet clustering algorithm that is designed for DIS event topologies. Events are required to have squared momentum-transfer Q 2 > 150 GeV 2 and inelasticity 0.2 < y < 0.7 . We report measurements of the production cross section of groomed event 1-jettiness and groomed invariant mass for several choices of grooming parameter. Monte Carlo model calculations and analytic calculations based on Soft Collinear Effective Theory are compared to the measurements.

Exclusive photoproduction of ρ 0 ( 770 ) mesons is studied using the H1 detector at the ep collider HERA. A sample of about 900,000 events is used to measure single- and double-differential cross sections for the reaction γ p → π + π - Y . Reactions where the proton stays intact ( m Y = m p ) are statistically separated from those where the proton dissociates to a low-mass hadronic system ( m p < m Y < 10 GeV ). The double-differential cross sections are measured as a function of the invariant mass m π π of the decay pions and the squared 4-momentum transfer t at the proton vertex. The measurements are presented in various bins of the photon–proton collision energy W γ p . The phase space restrictions are 0.5 ≤ m π π ≤ 2.2 GeV , | t | ≤ 1.5 GeV 2 , and 20 ≤ W γ p ≤ 80 GeV . Cross section measurements are presented for both elastic and proton-dissociative scattering. The observed cross section dependencies are described by analytic functions. Parametrising the m π π dependence with resonant and non-resonant contributions added at the amplitude level leads to a measurement of the ρ 0 ( 770 ) meson mass and width at m ρ = 770.8 - 2.7 + 2.6 ( tot. ) MeV and Γ ρ = 151.3 - 3.6 + 2.7 ( tot. ) MeV , respectively. The model is used to extract the ρ 0 ( 770 ) contribution to the π + π - cross sections and measure it as a function of t and W γ p . In a Regge asymptotic limit in which one Regge trajectory α ( t ) dominates, the intercept α ( t = 0 ) = 1.0654 - 0.0067 + 0.0098 ( tot. ) and the slope α ′ ( t = 0 ) = 0.233 - 0.074 + 0.067 ( tot. ) GeV - 2 of the t dependence are extracted for the case m Y = m p .

Inclusive e(+/-)p 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 root s = 319 GeV 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 four-momentum transfer squared, Q(2), between 60 and 50 000GeV(2), 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)(gamma Z). A measurement of the neutral current parity violating structure function F-2(gamma Z) 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.

A measurement of the inclusive ep scattering cross section is presented in the region of low momentum transfers, 0.2 GeV2 a parts per thousand currency signQ (2)a parts per thousand currency sign12 GeV2, and low Bjorken x, 5a <...10(-6)a parts per thousand currency signxa parts per thousand currency sign0.02. The result is based on two data sets collected in dedicated runs by the H1 Collaboration at HERA at beam energies of 27.6 GeV and 920 GeV for positrons and protons, respectively. A combination with data previously published by H1 leads to a cross section measurement of a few percent accuracy. A kinematic reconstruction method exploiting radiative ep events extends the measurement to lower Q (2) and larger x. The data are compared with theoretical models which apply to the transition region from photoproduction to deep inelastic scattering.

A bstract The cross section of the diffractive process e + p → e + Xp is measured at a centre-of-mass energy of 318 GeV, where the system X contains at least two jets and the leading final state proton p is detected in the H1 Very Forward Proton Spectrometer. The measurement is performed in photoproduction with photon virtualities Q 2 < 2 GeV 2 and in deep-inelastic scattering with 4 GeV 2 < Q 2 < 80 GeV 2 . The results are compared to next- to-leading order QCD calculations based on diffractive parton distribution functions as extracted from measurements of inclusive cross sections in diffractive deep-inelastic scattering.

The measurement of the jet cross sections by the H1 collaboration had been compared to various predictions including the next-to-next-to-leading order (NNLO) QCD calculations which are corrected in this erratum for an implementation error in one of the components of the NNLO calculations. The jet data and the other predictions remain unchanged. Eight figures, one table and conclusions are adapted accordingly, exhibiting even better agreement between the corrected NNLO predictions and the jet data.