The production of beauty and charm quarks in ep interactions has been studied with the ZEUS detector at HERA for exchanged four-momentum squared 5 < Q 2 < 1000 GeV 2 using an integrated luminosity of 354 pb −1 . The beauty and charm content in events with at least one jet have been extracted using the invariant mass of charged tracks associated with secondary vertices and the decay-length significance of these vertices. Differential cross sections as a function of Q 2 , Bjorken x, jet transverse energy and pseudorapidity were measured and compared with next-to-leading-order QCD calculations. The beauty and charm contributions to the proton structure functions were extracted from the double-differential cross section as a function of x and Q 2 . The running beauty-quark mass, m b at the scale m b , was determined from a QCD fit at next-to-leading order to HERA data for the first time and found to be m b (m b ) = 4.07 ± 0.14 (fit) +0.01 −0.07 (mod.) +0.05 −0.00 (param.) +0.08 −0.05 (theo.) GeV.Keywords: Lepton-Nucleon Scattering, QCD, Jets, B physics The ZEUS collaboration 53 IntroductionThe measurement of beauty and charm production in ep collisions at HERA is an important testing ground for perturbative Quantum Chromodynamics (pQCD), since the heavy-quark masses provide a hard scale that allows perturbative calculations to be made. At leading order, the dominant process for heavy-quark production at HERA is boson-gluon fusion (BGF). In this process, a virtual photon emitted by the incoming electron interacts with a gluon from the proton forming a heavy quark-antiquark pair. When the negative squared four-momentum of the virtual photon, Q 2 , is large compared to the proton mass, the interaction is referred to as deep inelastic scattering (DIS). For heavy-quark transverse momenta comparable to the quark mass, next-to-leading-order (NLO) QCD calculations based on the dynamical generation of the massive quarks [1][2][3][4] are expected to provide reliable predictions. Beauty and charm production in DIS has been measured using several methods by the H1 [5][6][7][8][9][10][11][12][13][14][15][16] and ZEUS [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] Inclusive jet cross sections in beauty and charm events are used in the analysis presented here to extract the heavy-quark contribution to the proton structure function F 2 with high precision, and to measure the b-quark mass. For this purpose, the long lifetimes of the weakly decaying b and c hadrons, which make the reconstruction of their decay vertices possible, as well as their large masses were exploited. Two discriminating variables, the significance of the reconstructed decay length and the invariant mass of the charged tracks associated with the decay vertex (secondary vertex), were used. This inclusive tagging method leads to a substantial increase in statistics with respect to previous ZEUS measurements.Differential cross sections as a function of Q 2 , the Bjorken scaling variable, x, jet transverse energy, E jet T , and pseudorapidit...

The photoproduction of isolated photons, both inclusive and together with a jet, has been measured with the ZEUS detector at HERA using an integrated luminosity of 374 pb(-1). Differential cross sections are presented in the isolated-photon transverse-energy and pseudorapidity ranges 6 < E-T(gamma) < 15 GeV and -0.7 < eta(gamma) < 0.9, and for jet transverse-energy and pseudorapidity ranges 4 < E-T(jet) < 35 GeV and -1.5 < eta(jet) < 1.8, for exchanged-photon virtualities Q(2) < 1 GeV2. Differential cross sections are also presented for inclusive isolated-photon production as functions of the transverse energy and pseudorapidity of the photon. Higher-order theoretical calculations are compared to the results. (C) 2014 The Authors. Published by Elsevier B.V

The neutral current e AE p cross section has been measured up to values of Bjorken x ≅ 1 with the ZEUS detector at HERA using an integrated luminosity of 187 pb −1 of e − p and 142 pb −1 of e þ p collisions at ffiffi ffi s p ¼ 318 GeV. Differential cross sections in x and Q 2 , the exchanged boson virtuality, are presented for Q 2 ≥ 725 GeV 2. An improved reconstruction method and greatly increased amount of data allows a finer binning in the high-x region of the neutral current cross section and leads to a measurement with much improved precision compared to a similar earlier analysis. The measurements are compared to Standard Model expectations based on a variety of recent parton distribution functions.

The reduced cross sections for e + p deep inelastic scattering have been measured with the ZEUS detector at HERA at three different centre-of-mass energies, 318, 251 and 225 GeV. The cross sections, measured double differentially in Bjorken x and the virtuality, Q 2 , were obtained in the region 0.13 ≤ y ≤ 0.75, where y denotes the inelasticity and 5 ≤ Q 2 ≤ 110 GeV 2 . The proton structure functions F 2 and F L were extracted from the measured cross sections.Dedicated to our friend and colleague Alexander Proskuryakov.

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