Search for new physics in events with same-sign dileptons and b-tagged jets in pp collisions at $ \sqrt {s} = 7 $ TeV

Abstract

A search for new physics is performed using isolated same-sign dileptons with at least two b-quark jets in the final state. Results are based on a 4.98 fb −1 sample of protonproton collisions at a centre-of-mass energy of 7 TeV collected by the CMS detector. No excess above the standard model background is observed. Upper limits at 95% confidence level are set on the number of events from non-standard-model sources. These limits are used to set constraints on a number of new physics models. Information on acceptance and efficiencies are also provided so that the results can be used to confront additional models in an approximate way.

The same-sign dilepton signature of RPV/MFV SUSY

“…The leading order (LO) cross section provided by Pythia is multiplied by the NLO K-factor computed with Prospino 2.1 [23] for normalization. To compute the efficiency of the CMS cuts on the signal, we essentially follow the procedure described in the CMS report [21] and its predecessors [24,25]. For details, see appendix A.…”

“…To recast the CMS SSDL+MET+b analysis in terms of the RPV SUSY model, we follow closely the instructions provided by CMS in [21] and its predecessors [24,25]. The only significant difference is in the treatment of leptons.…”

“…To do so, we impose a lepton isolation cut on the hadronized signal MC events. Following [24], Iso(ˆ ) is defined as a scalar sum of the lepton p T 's and photon and hadron E T 's within a cone of size ∆R ≡ (∆η) 2 + (∆φ) 2 < 0.3 about the lepton, not including the p T of the lepton itself:…”

“…To count b-tagged jets, we apply a p T -dependent tagging efficiency, parameterized in section 7 of [21], to all the b quarks that pass the jet kinematic cuts. To implement the cuts on H T and / E T , we compute "generator-level" quantities gen-H T and gen-/ E T , and use the turn-on efficiency curves parameterized in section 7 of [24] to get efficiencies for the cuts. gen-H T is the scalar sum of p T 's of the jets that pass the kinematic cuts, and gen-/ E T is the magnitude of the vector sum of the p T 's of non-interacting final-state particles.…”

XQCAT: eXtra Quark Combined Analysis Tool

“…• SUSY searches XQCAT implements four searches inspired by scenarios potentially induced by SUSY, each characterised by the presence of a different number of electrons/muons in the final state and large missing transverse energy: 0-lepton (α T ) [61], single lepton (L p ) [62], oppositesign dilepton (OS) [63] plus same-sign dilepton (SS) [64], considering the entire 4.98 fb −1 2011 dataset at √ s = 7 TeV. We also have accounted for the updated α T analysis [65] and same-sign [66] search at 8 TeV, based on 11.7 fb −1 and 10.5 fb −1 of luminosity, respectively.…”