Sharpening $m_{T2}$ cusps: the mass determination of semi-invisibly decaying particles from a resonance

Abstract

We revisit mass determination techniques for the minimum symmetric event topology, namely $X$ pair production followed by $X\to \ell N$, where $X$ and $N$ are unknown particles with the masses to be measured, and $N$ is an invisible particle, concentrating on the case where $X$ is pair produced from a resonance. We consider separate scenarios, with different initial constraints on the invisible particle momenta, and present a systematic method to identify the kinematically allowed mass regions in the $(m_N,m_X)$ plane. These allowed regions exhibit a cusp structure at the true mass point, which is equivalent to the one observed in the $m_{T2}$ endpoints in certain cases. By considering the boundary of the allowed mass region we systematically define kinematical variables which can be used in measuring the unknown masses, and find a new expression for the $m_{T2}$ variable as well as its inverse. We explicitly apply our method to the case that $X$ is pair produced from a resonance, and as a case study, we consider the process $pp\to A\to {\tilde{\chi }}_1^{+}{\tilde{\chi }}_1^{-}$, followed by ${\tilde{\chi }}_1^{\pm }\to {\ell }^{\pm }{\tilde{\nu }}_{\ell }$, in the Minimal Supersymmetric Standard Model and show that our method provides a precise measurement of the chargino and sneutrino masses, $m_X$ and $m_N$, at $14\mathrm{TeV}$ LHC with $300{\mathrm{fb}}^{-1}$ luminosity.

18 pages, 13 figures, version 2 updated to JHEP 06 (2014) 175

References in corpus (14)

• PYTHIA 6.4 Physics and Manual
• Vector boson pair production at the LHC
• 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
• Accurate Mass Determinations in Decay Chains with Missing Energy
• A Review of the Mass Measurement Techniques proposed for the Large Hadron Collider
• Inclusive transverse mass analysis for squark and gluino mass determination
• Handling jets + missing E_T channel using inclusive mT2
• FeynHiggs 2.7
• Mass determination in sequential particle decay chains
• Controlling ISR in sparticle mass reconstruction
• Extracting the Dark Matter Mass from Single Stage Cascade Decays at the LHC

Cited by in corpus (4)

• Quantum information and CP measurement in $H\to {\tau }^{+}{\tau }^{-}$ at future lepton colliders
• Exploring properties of long-lived particles in inelastic dark matter models at Belle II
• Constraints on sneutrino dark matter from LHC Run 1
• Monochromatic neutrino lines from sneutrino dark matter