Squark and Gaugino Hadroproduction and Decays in Non-Minimal Flavour Violating Supersymmetry

TL;DR

The paper analyzes squark and gaugino hadroproduction and decays in non-minimal flavour violating SUSY (NMFV MSSM) using the super-CKM basis and generalized couplings to capture CKM-induced quark–squark misalignment. It derives analytic cross sections and decay widths for all production channels and two-body decays, and performs scans of constrained MSSM parameter space under low-energy, EW precision, and cosmological bounds, defining four NMFV benchmark points with $\lambda$ up to a few tenths. It computes LO LHC production cross sections at $\sqrt{s}=14$ TeV as functions of $\lambda$, identifying regimes where NMFV effects are visible—especially in heavy-flavour channels and certain $t$/$u$-channel processes—and regimes where they are suppressed, constrained by BR$(b\to s\gamma)$ and relic density. The work provides analytic inputs and benchmark scenarios to facilitate collider studies of NMFV and motivates future experimental efforts with heavy-flavour tagging and dedicated Monte Carlo implementations.

Abstract

We present an extensive analysis of squark and gaugino hadroproduction and decays in non-minimal flavour violating supersymmetry. We employ the so-called super-CKM basis to define the possible misalignment of quark and squark rotations, and we use generalized (possibly complex) charges to define the mutual couplings of (s)quarks and gauge bosons/gauginos. The cross sections for all squark-(anti-)squark/gaugino pair and squark-gaugino associated production processes as well as their decay widths are then given in compact analytic form. For four different constrained supersymmetry breaking models with non-minimal flavour violation in the second/third generation squark sector only, we establish the parameter space regions allowed/favoured by low-energy, electroweak precision, and cosmological constraints and display the chirality and flavour decomposition of all up- and down-type squark mass eigenstates. Finally, we compute numerically the dependence of a representative sample of production cross sections at the LHC on the off-diagonal mass matrix elements in the experimentally allowed/favoured ranges.

Figures (29)

• Figure 1: Tree-level Feynman diagrams for the production of charged squark-antisquark pairs in quark-antiquark collisions.
• Figure 2: Tree-level Feynman diagrams for the production of neutral squark-antisquark pairs in quark-antiquark (top) and gluon-gluon collisions (bottom).
• Figure 3: Tree-level Feynman diagrams for the production of one down-type squark ($\tilde{q}_i$) and one up-type squark ($\tilde{q}_j^\prime$) in the collision of an up-type quark ($q$) and a down-type quark ($q^\prime$).
• Figure 4: Tree-level Feynman diagrams for the production of two up-type or down-type squarks.
• Figure 5: Tree-level Feynman diagrams for the associated production of squarks and gauginos.