Top quark forward-backward asymmetry in R-parity violating supersymmetry

Abstract

The interaction of bottom squark-mediated top quark pair production, occuring in the R-parity violating minimal supersymmetric standard model (MSSM), is proposed as an explanation of the anomalously large tt forward-backward asymmetry (FBA) observed at the Tevatron. We find that this model can give a good fit to top quark data, both the inclusive and invariant mass-dependent asymmetries, while remaining consistent (at the 2-σ level) with the total and differential production cross-sections. The scenario is challenged by strong constraints from atomic parity violation (APV), but we point out an extra diagram for the effective down quark-Z vertex, involving the same coupling constant as required for the FBA, which tends to weaken the APV constraint, and which can nullify it for reasonable values of the top squark masses and mixing angle. Large contributions to flavor-changing neutral currents can be avoided if only the third generation of sparticles is light.

LHC constraints on scalar diquarks

“…These appear in models with E 6 [2] or SU(2) L × SU(2) R × SU(4) C [3] symmetry, and in supersymmetry with R-parity violation [4]. Studies of diquark phenomenology mostly fall into three categories: (i) the LHC discovery reach for scalar diquarks [3,[5][6][7][8][9][10][11][12][13][14][15][16][17][18][19], (ii) explanations of the Tevatron tt forward-backward asymmetry [20][21][22][23][24][25][26][27][28], and (iii) contributions to n-n oscillations [13,[29][30][31][32][33][34][35]. Thus, there is a good deal of room to examine the effect of diquarks in other processes (for example, see refs.…”

LHC Constraints on Scalar Diquarks

“…These appear in models with E 6 [2] or SU (2) L × SU (2) R × SU (4) C [3] symmetry, and in supersymmetry with R-parity violation [4]. Studies of diquark phenomenology mostly fall into three categories: (i) the LHC discovery reach for scalar diquarks [3,[5][6][7][8][9][10][11][12][13][14][15][16][17][18][19], (ii) explanations of the Tevatron t t forward-backward asymmetry [20][21][22][23][24][25][26][27][28], and (iii) contributions to n-n oscillations [13,[29][30][31][32][33][34][35]. Thus, there is a good deal of room to examine the effect of diquarks in other processes (for example, see Refs.…”