Abstract
Abstract A classification of phenomenologically interesting supersymmetric extensions of the Standard-Model with a U(1) R symmetry is presented. Some of these are consistent with subsets of leptonic or baryonic “R-parity violating” (RPV) operators, thereby providing a natural motivation for them. We then focus on a particular class of models in which the U(1) R symmetry coincides with lepton number when restricted to the SM sector. In this case, the extension of lepton number to the superpartners is “non-standard”, implying, in particular, the existence of the leptonic RPV operators LLE c and LQD c , and a vacuum structure where one of the left-handed sneutrinos acquires a significant vacuum-expectation-value, while not being constrained by neutrino mass bounds. The model can be naturally consistent with bounds from electroweak precision measurements and flavor-changing processes. It can also easily accommodate the recently measured Higgs mass due to the existence of a scalar triplet that couples to the Higgs with an order one coupling, with only moderate fine-tuning. The phenomenology is rather rich and distinctive, with features such as heavy-but-natural Dirac gauginos, relaxed bounds on squarks, resonant slepton/sneutrino production, lepto-quark signals, as well as an interesting connection to neutrino physics arising from R-breaking. The broad qualitative features are discussed in this paper, with a more detailed phenomenological study carried out in a companion paper [1].
Highlights
We are extremely fortunate to live in a data-rich era of particle physics
We focus on a particular class of models in which the U(1)R symmetry coincides with lepton number when restricted to the SM sector
We focus on the case where the lepton number is tied to U(1)R symmetry, and study it in detail with the goal of laying out the LHC phenomenology
Summary
We are extremely fortunate to live in a data-rich era of particle physics. The discovery of a Higgs-like particle [2, 3] is a monumental achievement of the LHC. In the limiting case when Hd is heavy and is not part of the low-energy spectrum, the dominant contribution to down-type masses arises from the sneutrino vev, which is not constrained by neutrino masses unlike that in standard RPV models All these points will be explained in detail . The appendices deal with some details of R-symmetry breaking operators in appendix A, a description of a flavor ansatz for the λ and λ couplings (the standard notation for the coefficients of the LLEc and LQDc operators, respectively) in appendix B, and an estimate of the lower bound on λi couplings, given the observation of a lepto-quark (LQ) signal, in appendix C
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