Measuring supersymmetric particle masses at the LHC in scenarios with baryon number R-parity violating couplings.

Abstract

The measurement of sparticle masses in the Minimal Supersymmetric Standard Model at the LHC is analysed, in the scenario where the lightest neutralino, the ˜χ01 , decays into three quarks. Such decays, occurring through the baryon-number violating coupling λ′′ ijk, pose a severe challenge to the capability of the LHC detectors since the final state has no missing energy signature and a high jet multiplicity. We focus on the case λ′′ 212 6= 0 which is the most difficult experimentally. The proposed method is valid over a wide range of SUGRA parameter space with λ′′ 212 ∼ 10−5−0.1. Simulations are performed of the ATLAS detector at the Large Hadron Collider. Using the ˜χ01 from the decay chain ˜qL → ˜χ02 q → ˜lRℓq → ˜χ01 ℓℓq, we show that the ˜χ01 and ˜χ02 masses can be measured by 3-jet and 3-jet + lepton pair invariant mass combinations. At the SUGRA point m0 = 100 GeV, m1/2 = 300 GeV, A0 = 300 GeV, tan β = 10, μ > 0 and with λ′′ 212 = 0.005, we achieve statistical (systematic) errors of 3 (3), 3 (3), 0.3 (4) and 5 (12) GeV respectively for the masses of the ˜χ01 , ˜χ02 , ˜lR and ˜qL, with an integrated luminosity of 30 fb−1.