LSP squark decays at the LHC and the neutrino mass hierarchy

Abstract

The existence of R-parity in supersymmetric models can be naturally explained as being a discrete subgroup of gauged baryon minus lepton number (B − L). The most minimal supersymmetric B − L model triggers spontaneous R-parity violation, while remaining consistent with proton stability. This model is well-motivated by string theory and makes several interesting, testable predictions.Furthermore, R-parity violation contributes to neutrino masses, thereby connecting the neutrino sector to the decay of the lightest supersymmetric particle (LSP). This paper analyzes the decays of third generation squark LSPs into a quark and a lepton. In certain cases, the branching ratios into charged leptons reveal information about the neutrino mass hierarchy, a current goal of experimental neutrino physics, as well as the θ 23 neutrino mixing angle. Furthermore, optimization of leptoquark searches for this scenario is discussed. Using currently available data, the lower bounds on the third generation squarks are computed.

The minimal SUSY B − L model: from the unification scale to the LHC

“…A further study of the Wilson lines, spectra, mass scales and the unification of gauge couplings from the high-energy superstring point of view was presented in [30]. Combining the bottom-up and top-down approaches to the B − L MSSM, various aspects of both LHC and neutrino phenomenology were studied in the special case where a stop or a sbottom sparticle is the lightest supersymmetric particle (LSP) [31,32].…”

“…For LHC studies, see [17,18] as well as recent work on stop and sbottom LSP's in this context and the connection between their decays and the neutrino sector [31,32]. Predictions for the neutrino sector were discussed in [16,34,35].…”

“…In this paper, we impose these bounds except in the case of a stop or sbottom LSP. These two cases were explicitly studied in [31,32] and yielded the following lower bounds:…”

“…Again, the cyan and black points may obscure a low density of other points not satisfying their constraint. separated into wino-like and higgsino like charginos, and the stops and sbottom divisions are as in our earlier papers, references [31,32]. Note that this notation for the stops,t ad andt r , are only used to describe stop LSP's.…”

“…At this point, the JHEP06(2015)182 bilinear R-parity violating terms allow the LSP to decay. While only a few studies have been done on the phenomenology of the minimal B − L MSSM [17,18,31,32], there have been several works on the phenomenology of explicit bilinear R-parity violation, which has some similarities to this model. References to such papers are mentioned below although see [76][77][78][79] for general discussions.…”