for CMS Collaboration

arXiv2011

Centrality and pT dependence of charged particle RAA in PbPb collisions at sqrt(sNN) = 2.76 TeV

The transverse momentum pT spectra of charged particles is measured by CMS as a function of collision centrality in PbPb collisions at sqrt(sNN) = 2.76 TeV. The results are compared to a pp reference spectrum, constructed by interpolation between sqrt(s) = 0.9 and 7 TeV measurements. The nuclear modification factor RAA is constructed by dividing the PbPb pT spectrum, normalized to the number of binary collisions (Ncoll), by the pp spectrum. Measured RAA in 0-5% centrality bin is compared to several theoretical predictions.

nucl-ex↗

arXiv2009

Searching for Stopped Gluinos at CMS

We describe plans for a search for long-lived particles which will become stopped by the CMS detector. We will look for the subsequent decay of these particles during time intervals where there are no $pp$ collisions in CMS: during gaps between crossings in the LHC beam structure, and during inter-fill periods between the beam being dumped and re-injection. Such long living particles decays will be recorded with dedicated calorimeter triggers. For models predicting these particles, such as split-susy gluinos, the large cross-section combined with good stopping power of CMS, yields a significant number of triggerable decays. If LHC instantaneous luminosity approaches 10^32 cm^-2 s^-1 in 2009-10, 5-sigma significance can be established in a matter of days, since these decays occur on top of a negligible background. Due to limited size, this paper concentrates on main idea and expected results. More details are available in https://twiki.cern.ch/twiki/bin/view/CMS/PhysicsResults.

hep-ex↗