Abstract
We examine the detection prospects for a long-lived biνo, a pseudo-Dirac bino which is responsible for neutrino masses, at the LHC and at dedicated long-lived particle detectors. The biνo arises in U(1)R-symmetric supersymmetric models where the neutrino masses are generated through higher dimensional operators in an inverse seesaw mechanism. At the LHC the biνo is produced through squark decays and it subsequently decays to quarks, charged leptons and missing energy via its mixing with the Standard Model neutrinos. We consider long-lived biνos which escape the ATLAS or CMS detectors as missing energy and decay to charged leptons inside the proposed long-lived particle detectors FASER, CODEX-b, and MATHUSLA. We find the currently allowed region in the squark-biνo mass parameter space by recasting most recent LHC searches for jets+ . We also determine the reach of MATHUSLA, CODEX-b and FASER. We find that a large region of parameter space involving squark masses, biνo mass and the messenger scale can be probed with MATHUSLA, ranging from biνo masses of 10 GeV-2 TeV and messenger scales 102−11 TeV for a range of squark masses.
Highlights
The collider phenomenology of R-symmetric MSSM differs from the MSSM phenomenology
We find that a large region of parameter space involving squark masses, biνo mass and the messenger scale can be probed with MATHUSLA, ranging from biνo masses of 10 GeV-2 TeV and messenger scales 102−11 TeV for a range of squark masses
At this scale the biνo decays promptly and the strongest constraints come from ATLAS jets+E/ T search, where the missing energy comes from neutrinos produced in biνo decays in contrast to the LSP as in most other MSSM models
Summary
The biνo decays primarily via its mixing with light neutrinos, with branching fraction 1/3 to each channel: (i) B → W − +; (ii) B → Zν; and (iii) B → hν. Probability of a biνo surviving, i.e. not having decayed, after traveling a distance x = 25, 100, 500 meters, roughly corresponding to the length of the ATLAS detector, and the distance between the biνo production point and MATHUSLA and FASER respectively. We give the decay length γcτ of biνo assuming a benchmark boost factor of γ = 10, which shows the expected behavior where as the decay width gets smaller, the lifetime gets longer It can be seen in this plot that for ΛM = 100 TeV and MB > 100 GeV, which was covered in [13], biνo decays within a nanometer of the production point. We will focus on the reach of proposed, dedicated LLP experiments
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