scholarly journals Flavour observables and composite dynamics: leptons

2021 ◽  
Author(s):  
Florian Goertz
Keyword(s):  
Flavor Physics ◽  
Dipole Moments ◽  
Lepton Sector ◽  
Lepton Flavor ◽  
Flavor Symmetries ◽  
Composite Higgs ◽  
Partial Compositeness

AbstractWe review lepton flavor physics and corresponding observables in the composite Higgs framework with partial compositeness, considering ‘UV complete’ setups as well as effective and holographic approaches. This includes anarchic flavor setups, scenarios with flavor symmetries, and minimal incarnations of the see-saw mechanism that naturally predict non-negligible lepton compositeness. We focus on lepton flavor violating processes, dipole moments, and on probes of lepton flavor universality, all providing stringent tests of partial compositeness. We discuss the expected size of effects in the different approaches to lepton flavor, which will be useful to understand how a composite lepton sector could look like, given up-to-date experimental constraints.

scholarly journals Flavor physics in warped space

2015 ◽  
Vol 30 (15) ◽  
pp. 1540013 ◽  
Author(s):  
Gero von Gersdorff
Keyword(s):  
Cp Violation ◽  
Flavor Physics ◽  
Lepton Flavor Violation ◽  
Lepton Sector ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
Quark Flavor ◽  
Dimensional Models ◽  
Electroweak Precision ◽  
Kaluza Klein

We review constraints from quark and lepton flavor violation on extra dimensional models with warped geometry, both in the minimal and the custodial model. For both scenarios, Kaluza–Klein (KK) masses that are large enough to suppress constraints from electroweak precision tests (EWPT) also sufficiently suppress all quark flavor and CP violation, with the exception of CP violation in [Formula: see text] mixing and (to a lesser extend) in [Formula: see text] mixing. In the lepton sector the minimal scenario leads to excessively large contributions to μ→eγ transitions, requiring KK masses of at least 20 TeV or larger.

scholarly journals A more natural composite Higgs model

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
Hsin-Chia Cheng ◽  
Yi Chung
Keyword(s):  
Standard Model ◽  
Higgs Model ◽  
Quadratic Term ◽  
Beyond The Standard Model ◽  
Higgs Potential ◽  
Little Higgs ◽  
Composite Higgs ◽  
Partial Compositeness ◽  
Quartic Term ◽  
Natural Composite

Abstract Composite Higgs models provide an attractive solution to the hierarchy problem. However, many realistic models suffer from tuning problems in the Higgs potential. There are often large contributions from the UV dynamics of the composite resonances to the Higgs potential, and tuning between the quadratic term and the quartic term is required to separate the electroweak breaking scale and the compositeness scale. We consider a composite Higgs model based on the SU(6)/Sp(6) coset, where an enhanced symmetry on the fermion resonances can minimize the Higgs quadratic term. Moreover, a Higgs quartic term from the collective symmetry breaking of the little Higgs mechanism can be realized by the partial compositeness couplings between elementary Standard Model fermions and the composite operators, without introducing new elementary fields beyond the Standard Model and the composite sector. The model contains two Higgs doublets, as well as several additional pseudo-Nambu-Goldstone bosons. To avoid tuning, the extra Higgs bosons are expected to be relatively light and may be probed in the future LHC runs. The deviations of the Higgs couplings and the weak gauge boson couplings also provide important tests as they are expected to be close to the current limits in this model.

scholarly journals Top partner-resonance interplay in a composite Higgs framework

2018 ◽  
Vol 33 (11) ◽  
pp. 1841008 ◽  
Author(s):  
Juan Yepes ◽  
Alfonso Zerwekh
Keyword(s):  
Symmetry Breaking ◽  
Electric Dipole ◽  
Dipole Moments ◽  
Low Energy ◽  
Vector Resonance ◽  
Electric Dipole Moments ◽  
Parameter Spaces ◽  
Standard Model Fermion ◽  
Composite Higgs ◽  
The Standard Model

Guided us by the scenario of weak scale naturalness and the possible existence of exotic resonances, we have explored in a [Formula: see text] Composite Higgs setup the interplay among three matter sectors: elementary, top partners and vector resonances. We parametrize it through explicit interactions of spin-1 [Formula: see text]-resonances, coupled to the [Formula: see text]-invariant fermionic currents and tensors presented in this work. Such invariants are built upon the Standard Model fermion sector as well as top partners sourced by the unbroken [Formula: see text]. The mass scales entailed by the top partner and vector resonance sectors will control the low energy effects emerging from our interplaying model. Its phenomenological impact and parameter spaces have been considered via flavor-dijet processes and electric dipole moments bounds. Finally, the strength of the Nambu–Goldstone symmetry breaking and the extra couplings implied by the top partner mass scales are measured in accordance with expected estimations.

scholarly journals CHARGED LEPTON FLAVOR PHYSICS AND EXTRA DIMENSIONS

2007 ◽  
Vol 22 (20) ◽  
pp. 1513-1531
Author(s):  
E. O. ILTAN
Keyword(s):  
Charged Lepton ◽  
Extra Dimensions ◽  
Zero Mode ◽  
Dipole Moments ◽  
Higgs Doublet ◽  
Lepton Flavor ◽  
Gaussian Profile ◽  
Doublet Model ◽  
Two Higgs Doublet Model ◽  
Physical Quantities

We estimate the charged lepton electric dipole moments and the branching ratios of radiative lepton flavor violating decays in the framework of the two Higgs doublet model with the inclusion of two extra dimensions. Here, we consider that the new Higgs doublet is accessible to one of the extra dimensions with a Gaussian profile and the fermions are accessible to the other extra dimension with uniform zero-mode profile. We observe that the numerical values of the physical quantities studied enhance with the additional effects due to the extra dimensions and they are sensitive to the new Higgs localization.

scholarly journals Exploring new possibilities to discover a light pseudo-scalar at LHCb

2022 ◽  
Vol 82 (1) ◽  
Author(s):  
Diogo Buarque Franzosi ◽  
Giacomo Cacciapaglia ◽  
Xabier Cid Vidal ◽  
Gabriele Ferretti ◽  
Thomas Flacke ◽  
...  
Keyword(s):  
Mass Region ◽  
Decay Channels ◽  
Composite Higgs ◽  
Partial Compositeness ◽  
Tau Pairs ◽  
Muon Pairs ◽  
Pseudo Scalar

AbstractWe study the possibility of observing a light pseudo-scalar a at LHCb. We target the mass region $$2.5\,\mathrm{GeV}\lesssim m_a\lesssim 60\,\mathrm{GeV}$$ 2.5 GeV ≲ m a ≲ 60 GeV and various decay channels, some of which have never been considered before: muon pairs, tau pairs, D meson pairs, and di-photon. We interpret the results in the context of models of 4D Composite Higgs and Partial Compositeness in particular.

scholarly journals Lepton Flavor Violation beyond the MSSM

2015 ◽  
Vol 2015 ◽  
pp. 1-22 ◽  
Author(s):  
A. Vicente
Keyword(s):  
Standard Model ◽  
Parity Violation ◽  
New Physics ◽  
Lepton Flavor Violation ◽  
Lepton Sector ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
The Standard Model ◽  
Supersymmetric Models ◽  
Characteristic Features

Most extensions of the Standard Model lepton sector predict large lepton flavor violating rates. Given the promising experimental perspectives for lepton flavor violation in the next few years, this generic expectation might offer a powerful indirect probe to look for new physics. In this review we will cover several aspects of lepton flavor violation in supersymmetric models beyond the Minimal Supersymmetric Standard Model. In particular, we will concentrate on three different scenarios: high-scale and low-scale seesaw models as well as models withR-parity violation. We will see that in some cases the LFV phenomenology can have characteristic features for specific scenarios, implying that dedicated studies must be performed in order to correctly understand the phenomenology in nonminimal supersymmetric models.

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