Natural,R-parity violating supersymmetry, and horizontal flavor symmetries

Abstract

The absence so far of any supersymmetric signals at the LHC pushes towards a rethinking of the assumptions underlying the minimal supersymmetric Standard Model. Because the large missing E T searches are inadequate to detect a lightest supersymmetric partner (LSP) decaying within the detector, R-parity violating supersymmetry is still a good candidate for low-energy, natural supersymmetry. We show that, in Froggatt-Nielsen-like models of horizontal symmetries, specific textures for the R-parity violating couplings are dictated by the symmetry, with the largest coupling involving the third generation fields. Lepton number can be an accidental symmetry of the renormalizable superpotential and baryon number violation is given by a "u " d " d operator. The collider phenomenology then mimics the main features of minimal flavor violation R-parity violating supersymmetry. The LSP can evade current LHC supersymmetry searches and is allowed to be well below 1 TeV, and at the same time all the constraints from proton decay and other low-energy decays can be satisfied; in particular, dimension-five operators allowed by R-parity but dangerous for the proton are under control, while neutrino masses are generated by the Weinberg operator. Assuming sub-TeV (natural) superpartners, we obtain both upper and lower limits on the magnitude of the dominant R-parity violating coupling: a lower limit of order 10 À9 arises from null LHC searches on R-hadrons and heavy stable charged particles, while an upper limit of order 10 À2 follows from constraints on low-energy flavor-changing neutral currents. Displaced vertices are predicted in the lower end of this range.

New signatures and limits on R-parity violation from resonant squark production

“…In this work, we will focus on the resonant production of stops: the couplings λ 3jk are less constrained by flavor-changing neutral currents and flavor physics [12], while at the same time they are expected to be the largest in models where flavor symmetries determine a hierarchical structure of the RPV couplings [13][14][15][16]. We note that the cross section for any (right-handed) up-type squarkũ i is the same as for the stop, with the substitution λ 3jk → λ ijk .…”

“…In addition, all the limits become weaker as the relevant superpartner masses are increased. Such limits can be easily be accommodated by assuming particular flavor ansatze, in which the flavor structure of the Yukawas imposes hierarchical structures on the RPV couplings [13][14][15][16].…”

Models of dynamical R-parity violation

“…However, flavor should not be ignored. The reason is that the R-parity violating interactions break the approximate U (3) 5 non-abelian global flavor symmetries of the SM and may therefore induce flavor-violating interactions [39,40]. For example, the model presented in (3.18) leads to dimension-6 four-fermi operators that may or may not respect the R-parity and that violate baryon and lepton number.…”

Sneutrino Higgs models explain lepton non-universality in eejj, eνjj excesses

“…The lack of observation at colliders has lead to the introduction of many variations of supersymmetry such as R-parity violating (RPV) [3][4][5][6][7][8][9][10][11] and R-symmetric supersymmetry [12][13][14][15][16][17][18][19][20][21][22][22][23][24][25][26][27][28][29][30][31][32][33]. Constraints on SUSY, even in the context of RPV models, are already quite stringent [34][35][36].…”