Measurement of beauty and charm production in deep inelastic scattering at HERA and measurement of the beauty-quark mass

The ZEUS collaborationThe 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 trans- verse 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)_{−0.07}^{+0.01}(mod.)_{−0.00}^{+0.05}(param.)_{−0.05}^{+0.08}(theo.)GeV.We appreciate the contributions to the construction, maintenance and operation of the ZEUS detector of many people who are not listed as authors. The HERA machine group and the DESY computing staff are especially acknowledged for their success in providing excellent operation of the collider and the data-analysis environment. We thank the DESY directorate for their strong support and encouragement. It is a pleasure to thank the ABKM, CTEQ, JR and MSTW groups that provided the predictions for F_2^{b\overline{b}} shown in figure 12. We gratefully acknowledge the advice from S. Alekhin and R. Plačakytė concerning the appropriate usage of OPENQCDRAD and HERAFitter. Article funded by SCOAP