THE ZEPLIN III DETECTOR: RESULTS FROM SURFACE CALIBRATIONS

title: The ZEPLIN-III dark matter detector: Performance study using an end-to-end simulation tool
abstract: We present results from a GEANT4-based Monte Carlo tool for end-to-end simulations of the ZEPLIN-III dark matter experiment. ZEPLIN-III is a two-phase detector which measures both the scintillation light and the ionisation charge generated in liquid xenon by interacting particles and radiation. The software models the instrument response to radioactive backgrounds and calibration sources, including the generation, ray-tracing and detection of the primary and secondary scintillations in liquid and gaseous xenon, and subsequent processing by data acquisition electronics. A flexible user interface allows easy modification of detector parameters at run time. Realistic datasets can be produced to help with data analysis, an example of which is the position reconstruction algorithm developed from simulated data. We present a range of simulation results confirming the original design sensitivity of a few times 10−8 pb to the WIMP-nucleon cross-section.

title: Progress report from the UK Dark Matter search at Boulby Mine
abstract: The UK Dark Matter Collaboration is currently running a series of scintillation devices at the Boulby mine in North Yorkshire to search for the neutralino, the hypothetical WIMP solution to the dark matter problem. Results of the current NaI(T1) detector array will be discussed, illustrating a population of events of unknown origin. Diagnostic tests performed to investigate the origin of these anomalous events will be outlined, including alpha, beta and neutron calibrations.

title: Muon-induced background in the EDELWEISS dark matter search
abstract: A dedicated analysis of the muon-induced background in the EDELWEISS dark matter search has been performed on a data set acquired in 2009 and 2010. The total muon flux underground in the Laboratoire Souterrain de Modane (LSM) was measured to be Φ μ = ( 5.4 ± 0.2 - 0.9 + 0.5 )  muons/m 2 /d. The modular design of the μ -veto system allows the reconstruction of the muon trajectory and hence the determination of the angular dependent muon flux in LSM. The results are in good agreement with both MC simulations and earlier measurements. Synchronization of the μ -veto system with the phonon and ionization signals of the Ge detector array allowed identification of muon-induced events. Rates for all muon-induced events Γ μ = ( 0.172 ± 0.012 ) evts / ( kg d ) and of WIMP-like events Γ μ – n = 0.008 - 0.004 + 0.005 evts / ( kg d ) were extracted. After vetoing, the remaining rate of accepted muon-induced neutrons in the EDELWEISS-II dark matter search was determined to be Γ irred μ – n 6 · 10 - 4 evts / ( kg d ) at 90% C.L. Based on these results, the muon-induced background expectation for an anticipated exposure of 3000 kg d for EDELWEISS-III is N 3000 kg d μ – n 0.6 events.

title: The potential of liquid xenon for WIMP search: the ZEPLIN diagnostic array
abstract: A Liquid Xenon based WIMP detector diagnostic array is currently developed by the UKDMC with the help of international collaborators. After a brief reminder on the detection principle in Liquid Xenon, the individual detectors will be described. ZEPLIN I, a detector with a 4 kg fiducial mass with a background discrimination based on Pulse Shape Analysis, is already underground and starting operation. Two setups with improved background discrimination tools (as the ionisation is also recorded) are designed and scheduled to move underground in the second half of 2001. Both of them, ZEPLIN II and ZEPLIN III, are predicted to be sensitive to rate of 0.1–0.01 events/kg/day within 2 years of data taking. Furthermore, new ideas for lower background readout devices are studied, in order to avoid the use of PhotoMultiplier Tubes (PMTs).

title: Particle polarization in inclusive reactions

title: Study of forward Z + jet production in pp collisions at $ \sqrt{s} $ = 7 TeV
abstract: A bstractA measurement of the Z(→ μ+μ−) + jet production cross-section in pp collisions at a centre-of-mass energy $ \sqrt{s} $ = 7 TeV is presented. The analysis is based on an integrated luminosity of 1.0 fb−1 recorded by the LHCb experiment. Results are shown with two jet transverse momentum thresholds, 10 and 20 GeV, for both the overall cross-section within the fiducial volume, and for six differential cross-section measurements. The fiducial volume requires that both the jet and the muons from the Z boson decay are produced in the forward direction (2.0 < η < 4.5). The results show good agreement with theoretical predictions at the second-order expansion in the coupling of the strong interaction.

title: Composite superstring model for hadron amplitudes
abstract: Hadron dynamics is formulated in terms of interacting composite strings. These composite string amplitudes give other possible solution of duality equations for crossing channels in addition to classical string amplitudes. The composite strings carry quark flavour and spin degrees of freedom on edging two-dimensional surfaces. Consistent composite string models with extended N = 3 Virasoro superconformal symmetry are found. Simple amplitudes for interaction of π and K-mesons in this model are represented.

title: Amplitude analysis and the branching fraction measurement of $\bar{B}^0_s \to J/\psi K^+K^-$
abstract: An amplitude analysis of the final state structure in the Bs0→J/ψK+K- decay mode is performed using 1.0  fb-1 of data collected by the LHCb experiment in 7 TeV center-of-mass energy pp collisions produced by the LHC. A modified Dalitz plot analysis of the final state is performed using both the invariant mass spectra and the decay angular distributions. Resonant structures are observed in the K+K- mass spectrum as well as a significant non-resonant S-wave contribution over the entire K+K- mass range. The largest resonant component is the ϕ(1020), accompanied by f0(980), f2′(1525), and four additional resonances. The overall branching fraction is measured to be B(Bs0→J/ψK+K-)=(7.70±0.08±0.39±0.60)×10-4, where the first uncertainty is statistical, the second systematic, and the third due to the ratio of the number of Bs0 to B- mesons produced. The mass and width of the f2′(1525) are measured to be 1522.2±2.8-2.0+5.3  MeV and 84±6-5+10  MeV, respectively. The final state fractions of the other resonant states are also reported.

title: HADRON AMPLITUDES IN COMPOSITE SUPERCONFORMAL STRING MODEL
abstract: Dynamics of π, K-mesons interactions is formulated in terms of composite superconformal string model. Supersymmetry is defined on two-dimensional world surface only. Dimensionality of target space equals to four. The model treats usual hadron scale which is of order 1 GeV-2, as string scale α′. Intercept of leading meson trajectory equals to ½. Tree amplitudes are free from ghosts in physical state spectrum in accordance with usual classical superstring amplitudes. Interaction of π-mesons in the chiral limit in the model turns out in correspondence with description in terms of chiral Lagrangian for pions in QCD.

title: Production of high-energy muons in extensive air showers from primary el rays
abstract: The primary mechanism for the production of high-energy muons (E/sub / > 5 TeV) in extensive air showers from primary el rays is the production of muon pairs by shower photons in the field of a nucleus.