Professor Daniela Bortoletto

Abstract:

We present a search for a new narrow, spin-1, high mass resonance decaying to μ+μ-+X, using a matrix-element-based likelihood and a simultaneous measurement of the resonance mass and production rate. In data with 4.6fb-1 of integrated luminosity collected by the CDF detector in pp̄ collisions at √s=1960GeV, the most likely signal cross section is consistent with zero at 16% confidence level. We therefore do not observe evidence for a high mass resonance and place limits on models predicting spin-1 resonances, including M>1071GeV/c2 at 95% confidence level for a Z′ boson with the same couplings to fermions as the Z boson. © 2011 American Physical Society.

Abstract:

A search for microscopic black hole production and decay in pp collisions at a center-of-mass energy of 7 TeV has been conducted by the CMS Collaboration at the LHC, using a data sample corresponding to an integrated luminosity of 35 pb-1. Events with large total transverse energy are analyzed for the presence of multiple high-energy jets, leptons, and photons, typical of a signal expected from a microscopic black hole. Good agreement with the standard model backgrounds, dominated by QCD multijet production, is observed for various final-state multiplicities and model-independent limits on new physics in these final states are set. Using simple semi-classical approximation, limits on the minimum black hole mass are derived as well, in the range 3.5-4.5 TeV. These are the first direct limits on black hole production at a particle accelerator. © 2011 CERN.

Abstract:

Measurements of the total and differential cross sections dσ/dpTB and dσ/dyB for B+ mesons produced in pp collisions at √s=7TeV are presented. The data correspond to an integrated luminosity of 5.8pb-1 collected by the CMS experiment operating at the LHC. The exclusive decay B+→J/ψK+, with J/ψ→μ+μ-, is used to detect B+ mesons and to measure the production cross section as a function of pTB and yB. The total cross section for pTB>5GeV and |yB|<2.4 is measured to be 28.1±2.4±2.0±3.1μb, where the first uncertainty is statistical, the second is systematic, and the last is from the luminosity measurement. © 2011 American Physical Society.