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We consider the approximate U(2)^3 flavour symmetry exhibited by the quark sector of the Standard Model and all its possible breaking terms appearing in the quark Yukawa couplings. Taking an Effective Field Theory point of view, we…

High Energy Physics - Phenomenology · Physics 2015-06-05 Riccardo Barbieri , Dario Buttazzo , Filippo Sala , David M. Straub

There are strong similarities between charge-parity (CP) violating observables in hadronic $B$ decays (in particular $\Delta A^-_{\rm CP}$ in $B\to K\pi$) and direct CP violation in Kaon decays ($\epsilon^\prime$): All these observables are…

High Energy Physics - Phenomenology · Physics 2020-02-05 Andreas Crivellin , Christian Gross , Stefan Pokorski , Leonardo Vernazza

A non-Abelian flavour symmetry in a minimal supersymmetric standard model can explain the flavour structures in the Yukawa couplings and simultaneously solve the SUSY flavour problem. Similarly the SUSY CP problem can be solved if CP is…

High Energy Physics - Phenomenology · Physics 2010-02-23 L. Calibbi , J. Jones-Perez , A. Masiero , Jae-hyeon Park , W. Porod , O. Vives

The coming flavour precision era will allow to uncover various patterns of flavour violation in different New Physics (NP) scenarios that are presently washed out by hadronic and experimental uncertainties. We illustrate this by performing…

High Energy Physics - Phenomenology · Physics 2013-02-13 Andrzej J. Buras , Fulvia De Fazio , Jennifer Girrbach , Maria V. Carlucci

We extend the Zee model by introducing a vector-like lepton doublet and a flavor dependent global $U(1)$ symmetry. Flavor changing neutral currents in the quark sector can be naturally forbidden at tree level due to the $U(1)$ symmetry,…

High Energy Physics - Phenomenology · Physics 2021-09-15 Toshinori Matsui , Takaaki Nomura , Kei Yagyu

The basic features of quark and lepton mass matrices can be successfully explained by natural minima of a generic potential with dynamical Yukawa fields invariant under the $[\mathrm{SU(3)}]^5\times \mathcal{O}(3)$ flavor symmetry. If this…

High Energy Physics - Phenomenology · Physics 2017-01-18 Andreas Crivellin , Javier Fuentes-Martin , Admir Greljo , Gino Isidori

LHCb has reported deviations from the Standard Model in $b\to s\mu^+\mu^-$ transitions for which a new neutral gauge boson is a prime candidate for an explanation. As this gauge boson has to couple in a flavour non-universal way to muons…

High Energy Physics - Phenomenology · Physics 2015-09-25 Andreas Crivellin , Lars Hofer , Joaquim Matias , Ulrich Nierste , Stefan Pokorski , Janusz Rosiek

The quark sector of the Standard Model exhibits an approximate U(2)^3 flavour symmetry. This symmetry, broken in specific directions dictated by minimality, can explain the success of the Cabibbo-Kobayashi-Maskawa picture of flavour mixing…

High Energy Physics - Phenomenology · Physics 2017-08-23 Riccardo Barbieri , Dario Buttazzo , Filippo Sala , David M. Straub

We calculate a number of observables related to particle-antiparticle mixing and the branching ratios for the most interesting rare and CP-violating K and B decays in the Standard Model (SM3) extended by a fourth generation of quarks and…

High Energy Physics - Phenomenology · Physics 2010-12-01 Andrzej J. Buras , Björn Duling , Thorsten Feldmann , Tillmann Heidsieck , Christoph Promberger , Stefan Recksiegel

We study $b \to s \ell_1^+ \ell_2^-$ transitions, both for the lepton flavour conserving $\ell_1=\ell_2$ and violating case $\ell_1 \neq \ell_2$, in a minimal extension of the Standard Model proposed in [1]. In this framework, the Standard…

High Energy Physics - Phenomenology · Physics 2026-01-23 Pietro Colangelo , Fulvia De Fazio , Davide Milillo

We explore a $Z^\prime$ boson coupled only with the Standard Model (SM) fermions ($Z^\prime f\bar{f}$) in the framework of Minimal Flavor Violation. We study its effects on the processes with lepton flavor violation $\ell_j\to…

High Energy Physics - Phenomenology · Physics 2016-05-25 C. S. Kim , Xing-Bo Yuan , Ya-Juan Zheng

A U(2)^3 flavour symmetry acting on the first two generations of quarks partially explains the hierarchies of the yukawa couplings, and provides a natural embedding for Supersymmetry with heavier first two generations, where collider…

High Energy Physics - Phenomenology · Physics 2012-09-21 Filippo Sala

New neutral heavy gauge bosons ($Z^\prime$) are predicted within many extensions of the Standard Model. While in case they couple to quarks the LHC bounds are very stringent, leptophilic $Z^\prime$ bosons (even with sizable couplings) can…

High Energy Physics - Phenomenology · Physics 2021-06-30 Andrzej J. Buras , Andreas Crivellin , Fiona Kirk , Claudio Andrea Manzari , Marc Montull

We propose renormalizable models of new physics that can explain various anomalies observed in decays of B-mesons to electron and muon pairs. The new physics states couple to linear combinations of Standard Model fermions, yielding a…

High Energy Physics - Phenomenology · Physics 2016-07-20 Ben Gripaios , M. Nardecchia , S. A. Renner

We consider an abelian extension of the Standard Model (SM) comprising a new gauge group $U(1)^\prime$, with the neutral gauge boson $Z^\prime$ having flavour violating couplings to quarks and leptons. The fermion content is the same as in…

High Energy Physics - Phenomenology · Physics 2025-11-27 Pietro Colangelo , Fulvia De Fazio , Davide Milillo

We explore the possibility that lepton family numbers and baryon number are such good symmetries of Nature because they are the global remnant of a spontaneously broken gauge symmetry. An almost arbitrary linear combination of these…

High Energy Physics - Phenomenology · Physics 2020-01-15 Wolfgang Altmannshofer , Joe Davighi , Marco Nardecchia

The flavor changing and CP violating phenomena predicted in supersymmetric unified theories as a consequence of the large top quark Yukawa coupling, are investigated in the quark sector and compared with related phenomena in the lepton…

High Energy Physics - Phenomenology · Physics 2009-10-09 Riccardo Barbieri , Lawrence Hall , Alessandro Strumia

As a consequence of the large top quark Yukawa coupling, supersymmetric unified theories with soft supersymmetry breaking terms generated at the Planck scale predict lepton flavour and CP violating processes with significant rates. The…

High Energy Physics - Phenomenology · Physics 2009-10-09 R. Barbieri , L. Hall , A. Strumia

In the framework of the Standard Model Effective Field Theory, we compare the lower bounds on the scale of new physics possibly contributing to the $f\bar{f}h$ effective couplings, obtained from the measurements of different observables,…

High Energy Physics - Phenomenology · Physics 2022-05-25 J. Alonso-Gonzalez , A. de Giorgi , L. Merlo , S. Pokorski

We reconsider basic, in the sense of minimal field content, Pati-Salam x SU(3) family models which make use of the Type I see-saw mechanism to reproduce the observed mixing and mass spectrum in the neutrino sector. The goal of this is to…

High Energy Physics - Phenomenology · Physics 2010-11-26 Lorenzo Calibbi , Eung Jin Chun , Liliana Velasco-Sevilla
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