Weekly seminars

Inverse Hierarchy MFV: The Quark Dipole Operator

par Di Liu (LAPTh)

Europe/Paris
Auditorium (LAPTh)

Auditorium

LAPTh

Description
We present a new minimal flavor violation (MFV) scenario in 
which the up-type quark dipole coupling matrices $C_{uV}^{ij}$, $V=W$ or 
$B$,
are not only diagonal in the up-type mass eigenbasis but also have the 
eigenvalues that are inversely proportional to
the quark masses. Namely, $C_{uV}^{11}$ is the largest Wilson 
coefficient in the three families.
We analyze several aspects of $\mathcal{O}_{uW}$ in this ``inverse 
hierarchy MFV quark dipole'' framework.
In the infrared regime, we compare the flavor changing bounds of the 
$K^0-\bar{K}^0$ oscillation and exotic decays of the charged pion 
$\pi^+\rightarrow \bar{e}\nu_e\gamma$.
Due to the GIM cancellation and the helicity suppression, these bounds 
are loose for the first generation quark and require 
$|C_{uV}^{11}|<\mathcal{O}(10){\rm TeV}^{-2}$.
In the ultraviolet(UV) theories, the quark dipole operators are induced 
by the heavy states in the loops. Consequently, the quark masses receive 
sizable radiative corrections, leading to the light quarks' naturalness 
problem. In our framework, we provide a type of UV model in which the 
loop corrections to the mass cancel each other out. As a key part of our 
phenomenological study, we simulate the $pp\rightarrow W h\rightarrow 
\gamma\gamma\ell\nu$ process at the FCC-$hh$ colliderwith $\sqrt{s}=100$ 
TeV and $\mathcal{L}=30$  ab$^{-1}$. High-precision measurements there 
could set an upper bound on $C_{uW}$ in the ballpark of $10^{-2}$ 
TeV$^{-2}$ which is an order of magnitude stronger than the existing 
bounds obtained from LHC dilepton Drell-Yann channel analysis. As to 
$\mathcal{O}_{uB}$, we discuss it relation with $\mathcal{O}_{\varphi 
q}^{(1)}$ in the presence of the $H\leftrightarrow H^*$ symmetry.