Determining the squark mass at the LHC

Abstract

We propose a new way to determine the squark mass based on the shape of di-jet invariant mass distribution of supersymmetry (SUSY) di-jet events at the Large Hadron Collider (LHC). Our algorithm, which is based on event kinematics, requires that the branching ratio $B(\tilde{q}\to q{\tilde{z}}_1)$ is substantial for at least some types of squarks, and that $m_{{\tilde{z}}_1}^2/m_{\tilde{q}}^2\ll 1$. We select di-jet events with no isolated leptons, and impose cuts on the total jet transverse energy, $E_T^{tot}=E_T(j_1)+E_T(j_2)$, on $\alpha =E_T(j_2)/m_{jj}$, and on the azimuthal angle between the two jets to reduce SM backgrounds. The shape of the resulting di-jet mass distribution depends sensitively on the squark mass, especially if the integrated luminosity is sufficient to allow a hard enough cut on $E_T^{tot}$ and yet leave a large enough signal to obtain the $m_{jj}$ distribution. We simulate the signal and Standard Model (SM) backgrounds for 100 fb${}^{-1}$ integrated luminosity at 14 TeV requiring $E_T^{tot}>700$ GeV. We show that it should be possible to extract $m_{\tilde{q}}$ to within about 3% at 95% CL --- similar to the precision obtained using $m_{T2}$ --- from the di-jet mass distribution if $m_{\tilde{q}}\sim 650$ GeV, or to within $\sim 5$% if $m_{\tilde{q}}\sim 1$ TeV.

20 pages, 9 figures. Footnote added, updated references

References in corpus (11)

• Gluino Stransverse Mass
• Measuring superparticle masses at hadron collider using the transverse mass kink
• Using Subsystem MT2 for Complete Mass Determinations in Decay Chains with Missing Energy at Hadron Colliders
• Minimal Kinematic Constraints and MT2
• Search for squarks and gluinos in events with jets and missing transverse energy using 2.1 fb-1 of ppbar collision data at sqrt(s)=1.96 TeV
• Dijet Searches for Supersymmetry at the LHC
• MTGEN : Mass scale measurements in pair-production at colliders
• Transverse Observables and Mass Determination at Hadron Colliders
• Precision gluino mass at the LHC in SUSY models with decoupled scalars
• Precise reconstruction of sparticle masses without ambiguities
• Many Leptons at the LHC from the NMSSM