Abstract
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 4.07 \pm 0.14 (fit} ^{+0.01}_{-0.07} (mod.) ^{+0.05}_{-0.00} (param.) ^{+0.08}_{-0.05} (theo) GeV.
Highlights
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 F2 with high precision, and to measure the b-quark mass
1 C rad where ∆Yi is the width of the bin, kq denotes the scaling factor obtained from the fit, Nqhad,Monte Carlo (MC) is the number of generated jets in beauty or charm events at the MC hadron level, Crad is the QED radiative correction and L is the corresponding integrated luminosity
Inclusive jet production cross sections in events containing beauty or charm quarks have been measured in DIS at HERA, exploiting the long lifetimes and large masses of b and c hadrons
Summary
This analysis was performed with data taken with the ZEUS detector from 2004 to 2007, when HERA collided electrons with energy√Ee = 27.5 GeV with protons of energy 920 GeV, corresponding to a centre-of-mass energy s = 318 GeV. This data-taking period is denoted as HERA II. In the kinematic range of the analysis, charged particles were tracked in the central tracking detector (CTD) [34,35,36] and the microvertex detector (MVD) [37] These components operated in a magnetic field of 1.43 T provided by a thin superconducting solenoid. The luminosity was measured using the Bethe-Heitler reaction ep → eγp by a luminosity detector which consisted of independent lead–scintillator calorimeter [42,43,44] and magnetic spectrometer [45] systems
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