Readiness of CMS Simulation towards LHC Startup

CMS experiment has used detector simulation software in its conceptual as well as technical design. With the detector construction near its completion, the role of simulation has changed toward understanding collision data to be collected by CMS in near future. CMS simulation software is becoming a data driven, realistic and accurate Monte Carlo programme. The software architecture is described with some detail of the framework as well as detector specific components. Performance issues are discussed as well

&#945;<SUB>s</SUB> Measurements

The strong coupling constant, &#945;s, has been determined from many pure inclusive and semi-inclusive measurements. All these measurements, measured at different scales, are consistent among each other and the measurements can be combined to give &#945;s(mZ) = 0.118&#177;0.003

Quantum chromodynamics studies at LEP2

Several studies have been made to the hadronic final states in e+ e - collisions at LEP. Studies of the annihilation process at LEP2 have given rise to results on jet rate, event shape, heavy flavour production, inclusive momentum spectra, Bose-Einstein correlation and colour reconnection effects. Event shape studies have given rise to accurate determination of the strong coupling constant &#945; s using O (&#945;s2 ) with resummed leading and next-to-leading log calculation and also with power law corrections. Studies of 2-photon processes have yielded results on &#947;&#947; cross-section, heavy flavour production, photon structure function and &#947;* &#947;* scattering

Validation of geant4 hadronic physics models at intermediate energies

Geant4 provides a number of physics models at intermediate energies (corresponding to incident momenta in the range 1-20 GeV/c). Recently, these models have been validated with existing data from a number of experiments: (a) inclusive proton and neutron production with a variety of beams (&#960;-, &#960;+, p) at different energies between 1 and 9 GeV/c on a number of nuclear targets (from beryllium to uranium); (2) inclusive pion/kaon/proton production from 14.6 GeV/c proton beams on nuclear targets (from beryllium to gold); (3) inclusive pion production from pion beams between 3-13 GeV/c on a number of nuclear targets (from beryllium to lead). The results of simulation/data comparison for different GEANT4 models are discussed in the context of validating the models and determining their usage in physics lists for high energy application. Due to the increasing number of validations becoming available, and the requirement that they be done at regular intervals corresponding to the GEANT4 release schedule, automated methods of validation are being developed

Data driven approach to calorimeter simulation in CMS

CMS is looking forward to tune detector simulation using the forthcoming collision data from the LHC. CMS established a task force in February 2008 in order to understand and reconcile the discrepancies observed between the CMS calorimetry simulation and the test beam data recorded during 2004 and 2006. Within this framework, significant effort has been made to develop a strategy of tuning fast and flexible parameterizations describing showering in the calorimeter with available data from test beams. These parameterizations can be used within the context of Full as well as Fast Simulation. The study is extended to evaluate the use of first LHC collision data, when it becomes available, to rapidly tune the CMS calorimeter

Data Driven Approach to Calorimeter Simulation in CMS

CMS is looking forward to tune detector simulation using the forthcoming collision data from the LHC. CMS established a task force in February 2008 in order to understand and reconcile the discrepancies observed between the CMS calorimetry simulation and the test beam data recorded during 2004 and 2006. Within this framework, significant effort has been made to develop a strategy of tuning fast and flexible parameterizations describing showering in the calorimeter with available data from test beams. These parameterizations can be used within the context of Full as well as Fast Simulation. The study is extended to evaluate the use of first LHC collision data, when it becomes available, to rapidly tune the CMS calorimeter

Readiness of CMS Simulation towards LHC Startup

Abstract. CMS experiment has used detector simulation software in its conceptual as well as technical design. With the detector construction near its completion, the role of simulation has changed toward understanding collision data to be collected by CMS in near future. CMS simulation software is becoming a data driven, realistic and accurate Monte Carlo programme. The software architecture is described with some detail of the framework as well as detector specific components. Performance issues are discussed as well

Puzzles of excited charm meson masses

We attempt a comprehensive analysis of the low lying charm meson states which present several puzzles, including the poor determination of masses of several non-strange excited mesons. We use the well-determined masses of the ground states and the strange first excited states to `predict' the mass of the non-strange first excited state in the framework of heavy hadron chiral perturbation theory, an approach that is complementary to the well-known analysis of Mehen and Springer. This approach points to values for the masses of these states that are smaller than the experimental determinations. We provide a critical assessment of these mass measurements and point out the need for new experimental information.Comment: 9 pages, 1 figure, accepted for publication in Physics Letters