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Search: authors:"Alejandro Celis"

7 papers found.
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Yukawa enhancement of Z-mediated new physics in ∆S = 2 and ∆B = 2 processes

We discuss Yukawa-enhanced contributions from Z-mediated new physics to down-type quark ΔF = 2 processes in the framework of the standard model gauge-invariant effective theory (SMEFT). Besides the renormalization group (RG) mixing of the Z-mediating ψ 2 H 2 D operators into ΔF = 2 operators, we include at the electroweak scale one-loop (NLO) matching corrections consistently, ...

DsixTools: the standard model effective field theory toolkit

We present DsixTools, a Mathematica package for the handling of the dimension-six standard model effective field theory. Among other features, DsixTools allows the user to perform the full one-loop renormalization group evolution of the Wilson coefficients in the Warsaw basis. This is achieved thanks to the SMEFTrunner module, which implements the full one-loop anomalous dimension ...

Patterns of flavour violation in models with vector-like quarks

We study the patterns of flavour violation in renormalisable extensions of the Standard Model (SM) that contain vector-like quarks (VLQs) in a single complex representation of either the SM gauge group GSM or G SM ′ ≡ GSM ⊗ U(1)L μ − L τ . We first decouple VLQs in the M = (1 − 10) TeV range and then at the electroweak scale also Z, Z ′ gauge bosons and additional scalars to study ...

Phenomenology of an SU(2) × SU(2) × U(1) model with lepton-flavour non-universality

We investigate a gauge extension of the Standard Model in light of the observed hints of lepton universality violation in b → cℓν and b → sℓ + ℓ − decays at BaBar, Belle and LHCb. The model consists of an extended gauge group SU(2)1 × SU(2)2 × U(1) Y which breaks spontaneously around the TeV scale to the electroweak gauge group. Fermion mixing effects with vector-like fermions give ...

Stringy explanation of b → sℓ + ℓ − anomalies

We show that the recent anomalies in b → sℓ + ℓ − transitions observed by the LHCb collaboration can be accommodated within string motivated models with a low mass Z′ gauge boson. Such Z′ gauge boson can be obtained in compactifications with a low string scale. We consider a class of intersecting D-brane models in which different families of quarks and leptons are simultaneously ...

A class of invisible axion models with FCNCs at tree level

We build a class of invisible axion models with tree-level Flavor Changing Neutral Currents completely controlled by the fermion mixing matrices. The scalar sector of these models contains three-Higgs doublets and a complex scalar gauge singlet, with the same fermionic content as in the Standard Model. A horizontal Peccei-Quinn symmetry provides a solution to the strong CP problem ...

Flavour-changing top decays in the aligned two-Higgs-doublet model

We perform a complete one-loop computation of the two-body flavour-changing top decays t → ch and t → cV (V = γ, Z), within the aligned two-Higgs-doublet model. We evaluate the impact of the model parameters on the associated branching ratios, taking into account constraints from flavour data and measurements of the Higgs properties. Assuming that the 125 GeV Higgs corresponds to ...