55062868
Measurement of beauty production in deep inelastic scattering at HERA using decays into electrons
The production of beauty quarks in ep interactions has been studied with the ZEUS detector at HERA for exchanged four-momentum squared Q2>10 GeV2, using an integrated luminosity of 363 pb−1. The beauty events were identified using electrons from semileptonic b decays with a transverse momentum $0.9 < p_{T}^{e} < 8$ GeV and pseudorapidity |ηe|<1.5. Cross sections for beauty production were measured and compared with next-to-leading-order QCD calculations. The beauty contribution to the proton structure function F2 was extracted from the double-differential cross section as a function of Bjorken-x and Q2.
16863612
The spectrometer system for measuring ZEUS luminosity at HERA
The upgrade of the HERA accelerator has provided much increased collider luminosity. In turn, the improvements have necessitated a new design for the ZEUS luminosity measurements. The intense synchrotron radiation field, as well as the high probability of a bremsstrahlung photon in each bunch crossing, posed new experimental constraints. In this report, we describe how these challenges were met with the ZEUS luminosity spectrometer system. The design, testing and commissioning of the device are described, and the results from the initial operational experience are reported.
56102023
Production of Z(0) bosons in elastic and quasi-elastic ep collisions at HERA
The production of Z 0 bosons in the reaction ep→eZ 0 p (*) , where p (*) stands for a proton or a low-mass nucleon resonance, has been studied in ep collisions at HERA using the ZEUS detector. The analysis is based on a data sample collected between 1996 and 2007, amounting to 496pb -1 of integrated luminosity. The Z 0 was measured in the hadronic decay mode. The elasticity of the events was ensured by a cut on η max max is the maximum pseudorapidity of energy deposits in the calorimeter defined with respect to the proton beam direction. A signal was observed at the Z 0 mass. The cross section of the reaction ep→eZ 0 p (*) was measured to be σ(ep→eZ 0 p (*) )=0.13±0.06(stat.)±0.01(syst.) pb, in agreement with the Standard Model prediction of 0.16 pb. This is the first measurement of Z 0 production in ep collisions. © 2012 Elsevier B.V.
62786869
Measurement of isolated photons accompanied by jets in deep inelastic ep scattering
The production of isolated high-energy photons accompanied by jets has been measured in deep inelastic ep scattering with the ZEUS detector at HERA, using an integrated luminosity of 326pb -1 . Measurements were made for exchanged photon virtualities, Q 2 , in the range 10 to 350GeV 2 . The photons were measured in the transverse-energy and pseudorapidity ranges 4 γ jet <1.8. Differential cross sections are presented as functions of these quantities. Perturbative QCD predictions give a reasonable description of the shape of the measured cross sections over most of the kinematic range, but the absolute normalisation is typically in disagreement by 20-30%. © 2012 Elsevier B.V.
53324568
Measurement of heavy-quark jet photoproduction at HERA
Photoproduction of beauty and charm quarks in events with at least two jets has been measured with the ZEUS detector at HERA using an integrated luminosity of 133 pb−1. The fractions of jets containing b and c quarks were 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 jet transverse momentum, $p_{\mathrm {T}}^{\mathrm{jet}}$, and pseudorapidity, ηjet, were measured. The data are compared with previous measurements and are well described by next-to-leading-order QCD predictions.
116979994
The search for strange pentaquarks at ZEUS
A study of states and enhancements reconstructed using the invariant‐mass spectra associated with strange baryons has been performed in ep collisions with the ZEUS detector at HERA using an integrated luminosity of 121 pb−1. The invariant‐mass spectra were reconstructed in several kinematic regions with the main emphasis on the spectra which are sensitive to the production of pentaquarks. The candidate Θ+ signal was found to be produced predominantly in the forward hemisphere in the laboratory frame. This is unlike the case for the Λ(1520) or the Λc, and indicates that the Θ+ may have an unusual production mechanism related to proton‐remnant fragmentation.
115470739
Flavor tagged time-dependent angular analysis of the $B_s \rightarrow J/\psi \phi$ decay and extraction of $\Delta\Gamma$s and the weak phase $\phi_s$ in ATLAS
A measurement of the B0s→J/ψϕ decay parameters, updated to include flavor tagging is reported using 4.9  fb−1 of integrated luminosity collected by the ATLAS detector from s√=7  TeV pp collisions recorded in 2011 at the LHC. The values measured for the physical parameters are 
ϕs0.12±0.25(stat)±0.05(syst)  radΔΓs0.053±0.021(stat)±0.010(syst)  ps−1Γs0.677±0.007(stat)±0.004(syst)  ps 1|A∥(0)|20.220±0.008(stat)±0.009(syst)|A0(0)|20.529±0.006(stat)±0.012(syst)δ⊥=3.89±0.47(stat)±0.11(syst)  rad 
where the parameter ΔΓs is constrained to be positive. The S-wave contribution was measured and found to be compatible with zero. Results for ϕs and ΔΓs are also presented as 68% and 95% likelihood contours, which show agreement with the Standard Model expectations.
125079233
Systematic study of new data for extreme alpha decays
Recently discovered alpha decays with new or improved data, covering naturally occurring alpha emitters with long lifetimes, short-lived ones approaching the proton drip line, and decays of heavy and superheavy elements, have been studied in a systematic investigation within the modified two-potential approach for deformed nuclei by constructing the microscopic double-folding potential. It is found that the experimental half-lives are well reproduced in the density-dependent cluster model. Some predictions on natural alpha emitters and alpha decays of several proton emitters are made in this study. Moreover, the alpha-decay half-lives of even-even superheavy nuclei with Z = 110-114 and N = 184-194 are estimated to pursue the quite stable nuclei around the proton Z similar to 114 and neutron N similar to 184 shell closures. These predictions can be useful for future experiments aimed at searching for long-lived natural elements.
122517028
Structure of 8Li from a reaction cross-section measurement
We have precisely measured reaction cross sections (sigma(R)) for Li-8 using Be-9, C-12, Al-27, and proton targets at intermediate energies by the transmission method. From the energy dependence of the sigma(R) including the high energy data, the density distribution of Li-8 was deduced through a modified Glauber model. It is shown that Li-8 has a shorter tail structure in the density as compared with that of B-8 and the matter radius of Li-8 is similar to those of the other nonhalo Li isotopes. The result is consistent with the previous experiments that there is a tendency for Li-8 to be a skin nucleus.
122100793
Search for the $X_b$ and other hidden-beauty states in the $\pi^+ \pi^- \Upsilon(1 \rm S)$ channel at ATLAS
This Letter presents a search for a hidden-beauty counterpart of the X(3872) in the mass ranges of 10.05–10.31 GeV and 10.40–11.00 GeV, in the channel Xb→π+π−ϒ(1S)(→μ+μ−) , using 16.2 fb −1 of s=8 TeV pp collision data collected by the ATLAS detector at the LHC. No evidence for new narrow states is found, and upper limits are set on the product of the Xb cross section and branching fraction, relative to those of the ϒ(2S) , at the 95% confidence level using the CLS approach. These limits range from 0.8% to 4.0%, depending on mass. For masses above 10.1 GeV, the expected upper limits from this analysis are the most restrictive to date. Searches for production of the ϒ(13DJ) , ϒ(10860) , and ϒ(11020) states also reveal no significant signals.
123971708
Electroweak charge density distributions with parity-violating electron scattering
Parity-violating electron scattering (PVS) is an accurate and model-independent way to investigate the weak-charge density distributions of nuclei. In this paper, we study parity-violating electron scattering with the Helm model where the effects of spin-orbit currents on nuclear weak skins are taken into account. The conditions of two PVS measurements to constrain the surface thickness ${\ensuremath{\sigma}}_{W}$ of Helm weak-charge densities are investigated. According to the plane wave Born approximation, ${A}_{\mathrm{pv}}$ is expressed in terms of parameters of the corresponding Helm charge and weak-charge densities. After fitting the results of ${A}_{\mathrm{pv}}$ calculated from the phase-shift analysis method where the Coulomb distortion effects are incorporated, an empirical formula in terms of Helm model parameters for calculating ${A}_{\mathrm{pv}}$ is obtained. If two PVS measurements with different scattering angles are carried out, the modeled weak-charge density distributions with two parameters could be extracted from this empirical formula.