Photoproduction of isolated photons, inclusively and with a jet, at HERA
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 730 (2014) 293-301
Abstract:
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 6Erratum: Measurement of D*± production in deep inelastic scattering at HERA
Journal of High Energy Physics Springer Nature 2014:2 (2014) 106
Big-bang nucleosynthesis
Chinese Physics C IOP Publishing 38:9 (2014) 090001
Abstract:
A critical review is given of the current status of cosmological nucleosynthesis. In the framework of the Standard Model with 3 types of relativistic neutrinos, the baryon-to-photon ratio, $\eta$, corresponding to the inferred primordial abundances of deuterium and helium-4 is consistent with the independent determination of $\eta$ from observations of anisotropies in the cosmic microwave background. However the primordial abundance of lithium-7 inferred from observations is significantly below its expected value. Taking systematic uncertainties in the abundance estimates into account, there is overall concordance in the range $\eta = (5.7-6.7)\times 10^{-10}$ at 95% CL (corresponding to a cosmological baryon density $\Omega_B h^2 = 0.021 - 0.025$). The D and He-4 abundances, when combined with the CMB determination of $\eta$, provide the bound $N_\nu=3.28 \pm 0.28$ on the effective number of neutrino species. Other constraints on new physics are discussed briefly.Measurement of beauty and charm production in deep inelastic scattering at HERA and measurement of the beauty-quark mass
Journal of High Energy Physics 2014:9 (2014) 1-56
Abstract:
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 < Q2< 1000 GeV2using 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 Q2, 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 Q2. The running beauty-quark mass, mbat the scale mb, was determined from a QCD fit at next-to-leading order to HERA data for the first time and found to be mb(mb) = 4.07 ± 0.14 (fit)− 0.07+ 0.01(mod.)− 0.00+ 0.05(param.)− 0.05+ 0.08(theo.) GeV.Measurement of charm fragmentation fractions in photoproduction at HERA
Journal of High Energy Physics 2013:9 (2013)