122671773
Future neutrino astrophysics projects at the UK Boulby mine
Improved and expanded underground and surface facilities have been funded at the UK Boulby Mine to allow international participation in an expanded dark matter programme and new experiments in neutrino astrophysics. Neutrino detectors proposed are OMNIS and SIREN. OMNIS is a two-target detector for the mu and tau neutrinos from a Galactic supernova burst, giving unique information on both mass and mixing. SIREN is a real time low energy solar neutrino detector with energy spectroscopy capable of distinguishing between oscillation models of the solar deficit. Similar components and materials may allow OMNIS and SIREN to be combined into a single neutrino observatory. Comments are included on the future detectability of the integrated cosmological supernova flux and of the relic neutrino background.
119286983
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.
120314532
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.
12347950
The ZEPLIN-III dark matter detector: Performance study using an end-to-end simulation tool
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.
121667127
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).
115887438
Particle polarization in inclusive reactions
197461694
Evidence for the decay $X(3872)\rightarrow\psi(2S)\gamma$
Evidence for the decay mode $X(3872)\rightarrow\psi(2S)\gamma$ in $B^+\rightarrow X(3872)K^+$ decays is found with a significance of 4.4 standard deviations. The analysis is based on a data sample of proton-proton collisions, corresponding to an integrated luminosity of 3fb$^{-1}$ collected with the LHCb detector, at centre-of-mass energies of 7 and 8TeV. The ratio of the branching fraction of the $X(3872)\to\psi(2S)\gamma$ decay to that of the $X(3872)\rightarrow J/\psi \gamma$ decay is measured to be $$ \frac{Br(X(3872)\rightarrow\psi(2S)\gamma)}{Br(X(3872)\rightarrow J/\psi\gamma)} = 2.46\pm0.64\pm0.29, %\pm0.06,$$ where the first uncertainty is statistical and the second is systematic. The measured value agrees with expectations for a pure charmonium interpretation of the $X(3872)$ state and a mixture of charmonium and molecular interpretations. However, it does not support a pure $D\bar{D}^{*}$ molecular interpretation of the $X(3872)$state.
123747264
Heavy states of hadron string as weak interacting massive particles for Dark Matter
Massive states (of order 10 Gev and more) of hadron string (with scale 1 Gev) can have very small coupling constants with usual baryons of the Universe. Corresponding mean times for them are found to be order and even more than the age of the Universe. They are proposed as possible candidates for weak interacting massive particles (WIMP) of Dark Matter.
17306575
First measurement of the charge asymmetry in beauty-quark pair production.
The difference in the angular distributions between beauty quarks and antiquarks, referred to as the charge asymmetry, is measured for the first time in bb pair production at a hadron collider. The data used correspond to an integrated luminosity of 1.0 fb(-1) collected at 7 TeV center-of-mass energy in proton-proton collisions with the LHCb detector. The measurement is performed in three regions of the invariant mass of the bb system. The results obtained are A(C)(bb))(40 105 GeV/c(2)) = 1.6 ± 1.7 ± 0.6%, where A(C)(bb)) is defined as the asymmetry in the difference in rapidity between jets formed from the beauty quark and antiquark, where in each case the first uncertainty is statistical and the second systematic. The beauty jets are required to satisfy 2 < η < 4, E(T) >20 GeV, and have an opening angle in the transverse plane Δ ϕ > 2.6 rad. These measurements are consistent with the predictions of the standard model.
119162725
Observation of CP violation in B+ to DK+ decays
An analysis of B → DK and B → Dπ decays is presented where the D meson is reconstructed in the two-body final states: Kπ, KK, ππ and πK. Using 1.0 fb of LHCb data, measurements of several observables are made including the first observation of the suppressed mode B ± → [πK]DK . CP violation in B → DK decays is observed with 5.8σ significance. Submitted to Physics Letters B
118354146
Precision measurement of D meson mass differences
A bstractUsing three- and four-body decays of D mesons produced in semileptonic b-hadron decays, precision measurements of D meson mass differences are made together with a measurement of the D0 mass. The measurements are based on a dataset corresponding to an integrated luminosity of 1.0 fb−1 collected in pp collisions at 7 TeV. Using the decay D0 → K+K−K−π+, the D0 mass is measured to be
$ M\left( {{D^0}} \right)={{{1864.75\pm 0.15\left( {\mathrm{stat}} \right)\pm 0.11\left( {\mathrm{syst}} \right)\mathrm{MeV}}} \left/ {{{c^2}}} \right.}. $
 The mass differences
 $ \begin{array}{*{20}{c}} {{{{M\left( {{D^{+}}} \right)-M\left( {{D^0}} \right)=4.76\pm 0.12\left( {\mathrm{stat}} \right)\pm 0.07\left( {\mathrm{syst}} \right)\mathrm{MeV}}} \left/ {{{c^2}}} \right.},} \hfill \\ {{{{M\left( {{D^s}} \right)-M\left( {{D^{+}}} \right)=98.68\pm 0.03\left( {\mathrm{stat}} \right)\pm 0.04\left( {\mathrm{syst}} \right)\mathrm{MeV}}} \left/ {{{c^2}}} \right.}} \hfill \\ \end{array} $
 are measured using the D0 → K+K−π+π− and $ D_{(s)}^{+}\to {K^{+}}{K^{-}}{\pi^{+}} $ modes.
