1,978 research outputs found
Light neutralino in the MSSM: An update with the latest LHC results
We discuss the scenario of light neutralino dark matter in the minimal
supersymmetric standard model, which is motivated by the results of some of the
direct detection experiments --- DAMA, CoGENT, and CRESST. We update our
previous analysis with the latest results of the LHC. We show that new LHC
constraints disfavour the parameter region that can reproduce the results of
DAMA and CoGENT.Comment: 4 pages, 4 figures, to appear in the conference proceedings of TAUP
2011, Munich Germany, 5-9 September 201
Real-Time Treatment Planning Optimisation for Brachytherapy
In this paper, we present an integrated system for real-time dose distribution calculation and treatment planning optimisation for brachytherapy of prostate cancer, with a special emphasis on the visual integration of the dosimetry and target images obtained from the open magnetic resonance system. This system involves a fast method to calculate dose distributions of multiple concurrent radioactive sources, based on the combination of elements from a database of pre-calculated dose distribution maps for single sources, combined linearly to provide the final dose distribution map. Simulated annealing, in conjunction with the inverse planning method, is used to determine the source dwell times at pre-selected locations in order to optimally irradiate thetumour while preserving the surrounding healthy tissues. This algorithm, implemented in FORTRAN, is integrated into a computer-assisted treatment planning tool, written in JAVA, using the runtime class and RMI API of Java. The whole system is now under clinical testing at the Geneva University Hospital
The Semileptonic to Decays in QCD Sum Rules
We analyze the semileptonic rare decays of meson to and
axial vector mesons. The
decays are significant flavor changing neutral current decays of the meson.
These decays are sensitive to the new physics beyond SM, since these processes
are forbidden at tree level at SM. These decays occurring at the quark level
via transition, also provide new opportunities for
calculating the CKM matrix elements and . In this study, the
transition form factors of the decays
are calculated using three-point QCD sum rules approach. The resulting form
factors are used to estimate the branching fractions of these decays.Comment: 18 pages, 7 figures, version to appear in JP
First Operational Experience from the LHCb Silicon Tracker
The LHCb Silicon Tracker is a silicon micro-strip detector covering a sensitive area of 12 m2 with a total of 272k readout channels. The installation of the detector is complete and commissioning is making excellent progress. The detector has recorded first beam-induced events during LHC synchronization tests in August 2008 and in June 2009. These events have allowed the performance to be studied, and adjustments to the operational parameters to be made. In this contribution, we will draw first lessons from the in-situ commissioning of the Silicon Tracker, and present results from the reconstruction of data collected during the LHC synchronization tests
Performance of the LHCb Silicon Tracker with first data
The LHCb Silicon Tracker consists of two sub-detectors the Tracker Turicensis and Inner Tracker that are constructed from silicon microstrip technology. Performance studies of both sub-detectors using data taken during the LHC synchronization tests are described
Commissioning of the LHCb Silicon Tracker using data from the LHC injection tests
LHCb is a single-arm forward spectrometer dedicated to the study of the CP-violation and rare decays in the b-quark sector. An efficient and high precision tracking system is a key requirement of the experiment. The LHCb Silicon Tracker Project consists of two sub-detectors that make use of silicon micro-strip technology: the Tracker Turicensis located upstream of the spectrometer magnet and the Inner Tracker which covers the innermost part of the tracking stations after the magnet. In total an area of 12 m^2 is covered by silicon. In September 2008 and June 2009, injection tests from the SPS to the LHC were performed. Bunches of order 5x10^9 protons were dumped onto a beam stopper (TED) located upstream of LHCb. This produced a spray of ~10 GeV muons in the LHCb detector. Though the occupancy in this environment is relatively large, these TED runs have allowed a first space and time alignment of the tracking system. Results of these studies together and the overall detector performance obtained in the TED running will be discussed
The LHCb Silicon Tracker
The Silicon Tracker is a large-surface silicon micro-strip detector that covers the full acceptance of the experiment in a single tracking station upstream of the spectrometer magnet and the inner-most part of the three tracking stations downstream of the magnet. Special emphasis has been put on module quality assurance at all stages of the production. Various tests are performed after each production step and each module goes through several burn-in cycles. The design of the LHCb silicon detectors is described and the main lessons learnt from the R&D phase are summarized. Focus will be on the experience from module production and the quality assurance program
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Search for lepton-flavour-violating decays of Higgs-like bosons.
A search is presented for a Higgs-like boson with mass in the range 45 to 195 GeV/c2 decaying into a muon and a tau lepton. The dataset consists of proton-proton interactions at a centre-of-mass energy of 8 TeV , collected by the LHCb experiment, corresponding to an integrated luminosity of 2 fb-1 . The tau leptons are reconstructed in both leptonic and hadronic decay channels. An upper limit on the production cross-section multiplied by the branching fraction at 95% confidence level is set and ranges from 22 pb for a boson mass of 45 GeV/c2 to 4 pb for a mass of 195 GeV/c2
Radiation Monitoring System for the LHCb Inner Tracker
The performance requirements and the design of the Radiation Monitoring System (RMS) for the LHCb Inner Tracker are presented. Details of the Metal Foil Detector technology employed for the RMS are described, along with results from tests of RMS prototypes
Observation of two new baryon resonances
Two structures are observed close to the kinematic threshold in the mass spectrum in a sample of proton-proton collision data, corresponding
to an integrated luminosity of 3.0 fb recorded by the LHCb experiment.
In the quark model, two baryonic resonances with quark content are
expected in this mass region: the spin-parity and
states, denoted and .
Interpreting the structures as these resonances, we measure the mass
differences and the width of the heavier state to be
MeV,
MeV,
MeV, where the first and second
uncertainties are statistical and systematic, respectively. The width of the
lighter state is consistent with zero, and we place an upper limit of
MeV at 95% confidence level. Relative
production rates of these states are also reported.Comment: 17 pages, 2 figure
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