The Hunt for New Physics in the Flavour Sector with up vector-like quarks

TL;DR

This paper investigates the potential for new physics in the flavour sector by analyzing anomalies and proposing a model with an up vector-like quark, predicting observable deviations from the Standard Model in various flavour processes.

Contribution

It introduces a simple extension of the Standard Model with an up vector-like quark, providing detailed predictions and correlations for flavour observables and constraints from recent data.

Findings

Deviations from the SM in $b d$ sector observables like $ ext{A}_{SL}^d$ and $B_d^0 o \mu^+\mu^-$

Preference for an up vector-like quark with mass below 600 GeV at 1$\sigma$

Potential signals in rare processes such as $K_L^0 o \pi^0 u ar{ u}$ and $t o Zq$

Abstract

We analyse the possible presence of New Physics (NP) in the Flavour Sector and evaluate its potential for solving the tension between the experimental values of $\AJPKs$ and $\BTNu$ with respect to the Standard Model (SM) expectations. Updated model independent analyses, where NP contributions are allowed in Bd - anti-Bd and Bs - anti-Bs transitions, suggest the need of New Physics in the $bd$ sector. A detailed analysis of recent Flavour data is then presented in the framework of a simple extension of the SM, where a $Q=2/3$ vector-like isosinglet quark is added to the spectrum of the SM. Special emphasis is given to the implications of this model for correlations among various measurable quantities. We include constraints from all the relevant quark flavour sectors and give precise predictions for selected rare processes. We find important deviations from the SM in observables in the $bd$ sector like the semileptonic asymmetry $\asld$, $B_{d}^{0}\to \mu ^{+}\mu ^{-}$ and $A^s_{SL}-A^d_{SL}$. Other potential places where NP can show up include $A_{J/\Psi\Phi}$, $\gamma$, $K_{L}^{0}\to \pi^{0}\nu \bar{\nu}$, $t\to Zq$ and $D^{0}\to \mu ^{+}\mu ^{-}$ among others. The experimental data favours in this model the existence of an up vector-like quark with a mass below $600(1000)$ GeV at $1(2)$ $\sigma $.