Hidden Thresholds: A Technique for Reconstructing New Physics Masses at Hadron Colliders

Abstract

We present an improved method of reconstructing New Physics (NP) masses from invariant mass endpoints. While the traditional method focuses on a single NP decay, our method considers the decays of two or more NP particles ($ABC...$) in a grander decay chain: $anything\to ABC...\to ...\to jets+leptons$. Though the center-of-mass energy $E_{CM}$ of `anything' varies unpredictably at a hadron collider, a sample of many events nonetheless expresses features of threshold production $E_{CM}=m_A+m_B+...$: invariant masses constructed from the final jet and lepton momenta are correlated in a way that makes their threshold endpoints visually obvious in a scatterplot. We illustrate this technique for the production of two neutralinos in the MSSM: $anything\to {\tilde{\chi }}_i^0{\tilde{\chi }}_j^0$ ($i,j=2,3,4$) which subsequently decay via on- or off-shell sleptons to four leptons. Assuming the relevant SUSY spectrum is below $1TeV$ and squarks/gluinos eventually decay to neutralinos, our MC study shows that one low-luminosity year at the LHC ($10-30f{b}^{-1}$) can quantitatively determine on- versus off-shell decays and find the relevant neutralino and slepton masses to less than 10 percent.

15 pages, 6 figures; Discussion simplified

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Cited by in corpus (12)

• Using Subsystem MT2 for Complete Mass Determinations in Decay Chains with Missing Energy at Hadron Colliders
• Dark Matter Particle Spectroscopy at the LHC: Generalizing MT2 to Asymmetric Event Topologies
• Transverse masses and kinematic constraints: from the boundary to the crease
• Using kinematic boundary lines for particle mass measurements and disambiguation in SUSY-like events with missing energy
• Precise reconstruction of sparticle masses without ambiguities
• Supersymmetric particle mass measurement with invariant mass correlations
• Four-lepton LHC events from MSSM Higgs boson decays into neutralino and chargino pairs
• Effects of QCD radiation on inclusive variables for determining the scale of new physics at hadron colliders
• On Measuring Split-SUSY Neutralino and Chargino Masses at the LHC
• Improving SUSY Spectrum Determinations at the LHC with Wedgebox Technique
• Determination of supersymmetric masses using kinematic fits at the LHC
• Hidden Thresholds: Reconstructing NP Masses