相关论文: Vector-like Singlet Quarks: a Roadmap

Nelson-Barr models solve the strong CP problem based on spontaneous CP violation and generically requires vector-like quarks (VLQs) mixing with standard quarks to transmit the CP violation. We devise an explicit parametrization for the case…

A gluon resonance G of mass below 1 TeV could be the origin of the t\bar{t} forward-backward asymmetry observed at the Tevatron provided that new decay modes G->\bar{q}Q, with q a standard quark and Q its massive excitation, make G broad…

Based on flavour symmetries only, there are two ways to give rise to an effective description of flavour physics in the quark sector close to the CKM picture: one is based on $U(3)_q\times U(3)_u\times U(3)_d$ (or equivalent) and the other…

Like many other models, Composite Higgs Models feature the existence of heavy vector-like quarks. Mixing effects between the Standard Model fields and the heavy states, which can be quite large in case of the top quark, imply deviations…

Studying heavy flavour physics is driven by multiple motivations: to probe our theoretical control over QCD; enhance our information on gluon and sea quark structure functions; use heavy flavour production as signal for the onset of the…

Vector-like quark is a common feature in many new physics models. We study the vector-like quark production as an s-channel resonance at the Large Hadron Collider for the vector-like quarks mainly mixing with the top- and bottom-quark in…

We study the flavor invariants of the SM augmented by one singlet vector-like quark. Aided by the Hilbert series, we construct all the basic invariants with which any flavor invariant can be written as a polynomial. In special, this theory…

We propose a KSVZ-type axion framework in which vector-like quarks (VLQ) and colored scalars generate Dirac neutrino masses radiatively. The global Peccei-Quinn symmetry (under which the exotic fermions are charged) addresses the strong CP…

Extending previous work on this subject, we evaluate the impact of vector-like fermions at next-to-leading order accuracy in models with a massive vector leptoquark embedded in the $SU(4)\times SU(3)^\prime\times SU(2)_L\times U(1)_X$ gauge…

Extensions of the MSSM often predict the existence of new fermions and their scalar superpartners which are vectorlike with respect to the standard model gauge group but may be chiral under additional gauge factors. In this paper we explore…

We point out that hints of deviations from unitarity in the first row of the CKM matrix may be explained by the presence of a single vector-like top. We study how the stringent experimental constraints arising from CP Violation in the kaon…

We explore CP-violating (CPV) effects of heavy New Physics in flavour-changing quark dipole transitions, within the framework of Standard Model Effective Field Theory (SMEFT). First, we establish the relevant dimension six operators and…

Extending the Standard Model with higher-dimensional operators in an effective-field-theory (EFT) approach provides a systematic framework to study new-physics (NP) effects from a bottom-up perspective, as long as the NP scale is…

We consider the phenomenological signatures of Simplified Models of Flavourful Leptoquarks, whose Beyond-the-Standard Model (SM) couplings to fermion generations occur via textures that are well motivated from a broad class of ultraviolet…

We study renormalizable extensions of the standard model that contain vector-like fermions in a (single) complex representation of the standard model gauge group. There are 11 models where the vector-like fermions Yukawa couple to the…

We discuss $Z$ mediated flavour changing neutral currents within a model where the hierarchical quark and lepton masses are explained via a fourth vector-like family, together with a scalar sector consisting of two Higgs doublets augmented…

Simplified models provide a useful tool to conduct the search and exploration of physics beyond the Standard Model in a model-independent fashion. In this work we consider the complementarity of indirect searches for new physics in Higgs…

We confront the new physics models with extra iso-singlet down quarks in the new CP violation experimental era with $\sin{(2\beta)}$ and $\epsilon'/\epsilon$ measurements, $K^+ \to \pi^+ \nu \bar{\nu}$ events, and $x_s$ limits. The…

The large number of top quarks produced at the LHC and possible future hadron colliders allows to study rare decays of this particle. In many well motivated models of new physics, for example in non-minimal composite-Higgs models, the…

The mixing of the known quarks with new heavy singlets can modify significantly some observables with respect to the Standard Model predictions. We analyse the range of deviations permitted by the constraints from precision electroweak data…