0000000000407406
AUTHOR
J. A. Valls
Searching for $B_c$ mesons in the ATLAS experiment at LHC
We discuss the feasibility of the observation of the signal from $B_c$ mesons in the ATLAS experiment at the LHC. In particular, we address the decay mode $B_c{\rightarrow}J/\psi \pi$ followed by the leptonic decay $J/\psi{\rightarrow}\mu^+\mu^-$, which should permit an accurate measurement of the $B_c$ mass. We performed a Monte Carlo study of the signal and background concluding that a precision of $\approx$ 1 MeV for the $B_c$ mass could be achieved after one year of running at $\lq\lq$low" luminosity. The semileptonic decay $B_c{\rightarrow}J/\psi\ {\mu}^+{\nu}_{\mu}$ is also considered for a possible extraction of ${\mid}V_{cb}{\mid}$.
A layer correlation technique for pion energy calibration at the 2004 ATLAS Combined Beam Test
A new method for calibrating the hadron response of a segmented calorimeter is developed and successfully applied to beam test data. It is based on a principal component analysis of energy deposits in the calorimeter layers, exploiting longitudinal shower development information to improve the measured energy resolution. Corrections for invisible hadronic energy and energy lost in dead material in front of and between the calorimeters of the ATLAS experiment were calculated with simulated Geant4 Monte Carlo events and used to reconstruct the energy of pions impinging on the calorimeters during the 2004 Barrel Combined Beam Test at the CERN H8 area. For pion beams with energies between 20GeV…
TileCal optical multiplexer board 9U prototype
This paper presents the architecture and the status of the optical multiplexer board (OMB) for the ATLAS/LHC Tile hadronic calorimeter (TileCal). This board will analyze the front-end data CRC to prevent bit and burst errors produced by radiation. Besides, due to its position within the data acquisition chain it will be used to emulate front-end data for tests. The first two prototypes of the final OMB 9U version have been produced at CERN. Detailed design issues and manufacture features of these prototypes are described. These prototypes are being validated whereas some firmware developments are being implemented in the programmable devices of the board. Functional descriptions of the boar…
A search for new physics in dijet mass and angular distributions in pp collisions at [subscript √s=7] TeV measured with the ATLAS detector
A search for new interactions and resonances produced in LHC proton–proton (pp) collisions at a centre-of-mass energy ps = 7 TeV was performed with the ATLAS detector. Using a dataset with an integrated luminosity of 36 pb−1, dijet mass and angular distributions were measured up to dijet masses of 3.5 TeV and were found to be in good agreement with Standard Model predictions. This analysis sets limits at 95% CL on various models for new physics: an excited quark is excluded for mass between 0.60 and 2.64 TeV, an axigluon hypothesis is excluded for axigluon masses between 0.60 and 2.10 TeV and quantum black holes are excluded in models with six extra space–time dimensions for quantum gravity…