Speaker
Description
We study the supersymmetric (SUSY) effects on $C_7(\mu_b)$ and $C'_7(\mu_b)$
which are the Wilson coefficients (WC) for $b \to s \gamma$ at b quark
mass scale $\mu_b$ and are closely related to radiative B meson decays.
The SUSY-loop contributions to $C_7(\mu_b)$ and $C'_7(\mu_b)$ are calculated
at leading order (LO) in the Minimal Supersymmetric Standard Model (MSSM) with
general quark flavor violation (QFV). For the first time we perform a systematic
MSSM parameter scan for the WCs $C_7(\mu_b)$ and $C'_7(\mu_b)$ respecting all
the relevant constraints, i.e. the theoretical constraints from vacuum stability
conditions and the experimental constraints, such as those from $K$- and
$B$-meson data and electroweak precision data, as well as recent limits on SUSY
particle masses and the 125 GeV Higgs boson data from LHC experiments.
From the parameter scan, we find the following:
(1) The MSSM contribution to Re($C_7(\mu_b)$) can be as large as $\sim \pm 0.05$
which could correspond to about 3$\sigma$ significance of New Physics (NP)
signal in the future LHCb-Upgrade and Belle II experiments.
(2) The MSSM contribution to Re($C'_7(\mu_b)$) can be as large as $\sim -0.08$
which could correspond to about 4$\sigma$ significance of NP signal
in the future LHCb-Upgrade and Belle II experiments.
(3) These large MSSM contributions to the WCs are mainly
due to (i) large scharm-stop mixing and large scharm/stop involved
trilinear couplings $T_{U23}$, $T_{U32}$ and $T_{U33}$, (ii) large
sstrange-sbottom mixing and large sstrange-sbottom involved
trilinear couplings $T_{D23}$, $T_{D32}$ and $T_{D33}$ and
(iii) large bottom Yukawa coupling $Y_b$ for large $\tan\beta$
and large top Yukawa coupling $Y_t$.
In case such large NP contributions to the WCs are really observed
in the future experiments at Belle II and LHCb-Upgrade, this could
be the imprint of QFV SUSY (the MSSM with general QFV) and would
encourage to perform further studies of the WCs $C'_7(\mu_b)$ and
$C_7^{MSSM}(\mu_b)$ at higher order (NLO/NNLO) level in this model.
Note: This work is based on collaboration with Helmut Eberl, Elena Ginina
(HEPHY, Vienna) and Akimasa Ishikawa (Belle II, KEK).
Reference: arXiv:2106.15228 [hep-ph] (under submission to a journal)
