arXiv subjects

Sergio Ferrando Solera

Publications and source records attributed to Sergio Ferrando Solera.

4 recordsLinked to original sources

arXiv2026

Symmetry-restoring finite counterterms of SMEFT four-fermion operator insertions at one loop

Some effects induced by SMEFT operators at one loop have attracted a lot of attention in recent years, in particular, the renormalization of divergences by physical operators in single insertions of dimension-6 operators. Important non-logarithmically enhanced contributions must also be calculated. We discuss dimensional regularization in the Breitenlohner-Maison-'t Hooft-Veltman scheme. The goal here consists of determining in this scheme quantum effects in chiral theories at one loop. Namely, the determination of finite counterterms at one loop that reestablish the Slavnov-Taylor identities, which follow from gauge symmetries. These counterterms are necessary due to the presence of evanescent symmetry-breaking terms in the classical Lagrangian needed to regularize fermion propagators. We consider a technique that allows an easier calculation of such finite effects, relying on the identification of $(D-4)/(D-4)$ terms of one-loop amplitudes with an external ghost leg. We focus on dimension-6 four-fermion operators, identifying all finite counterterms in the Breitenlohner-Maison-'t Hooft-Veltman scheme at one loop, and as expected find no obstructions to the Slavnov-Taylor identities that cannot be cured by finite counterterms. This represents one step towards moving to higher order calculations.

hep-ph↗

arXiv2024

Model Independent Bounds on Left-Right Gauge Boson Masses from LHC Run 2 and Flavour Observables

Left-Right Models (LRMs) are one of the most relevant extensions of the Standard Model (SM) of particle physics. They introduce an extended gauge sector and can restore parity (P) or charge conjugation (C) symmetries at high enough energies. These theories can be embedded in other more fundamental ones with larger gauge groups. Consequently, the restoration of the C or P symmetries can be pushed towards higher energy scales compared to the scale of the Spontaneous Symmetry Breaking (SSB) of the LRM gauge group. We study three LRMs with different specific realizations of the scalar sector without imposing any additional discrete symmetry on the theory. We present bounds on the masses of the new gauge bosons using data from the LHC Run 2 and study rare meson decays, discussing the structure of the right-handed quark mixing matrix and the impact of the neutrino and scalar sectors. Collider bounds valid for specific LRM realizations are alleviated bringing New Physics (NP) effects in flavour observables closer to an observable level.

hep-ph↗

arXiv2024

Direct bounds on Left-Right gauge boson masses

While the third run of the Large Hadron Collider (LHC) is ongoing, the underlying theory that extends the Standard Model remains so far unknown. Left-Right Models (LRMs) introduce a new gauge sector, and can restore parity symmetry at high enough energies. If LRMs are indeed realized in nature, the mediators of the new weak force can be searched for in colliders via their direct production. We recast existing experimental limits from the LHC Run 2 and derive generic bounds on the masses of the heavy LRM gauge bosons. As a novelty, we discuss the dependence of the $W_R$ and $Z_R$ total decay width on the LRM scalar content, obtaining model-independent bounds within the specific realizations of the LRM scalar sectors analysed here. These bounds avoid the need to detail the spectrum of the scalar sector, and apply in the general case where no discrete symmetry is enforced. Moreover, we emphasize the impact on the $W_R$ production at LHC of general textures of the right-handed quark mixing matrix without manifest left-right symmetry. We find that the $W_R$ and $Z_R$ masses are constrained to lie above $2$ TeV and $4$ TeV, respectively.

hep-ph↗

arXiv2023

Direct bounds on Left-Right gauge boson masses at LHC Run 2

While the third run of the Large Hadron Collider (LHC) is ongoing, the underlying theory that extends the Standard Model remains so far unknown. Left-Right Models (LRMs) introduce a new gauge sector, and can restore parity symmetry at high enough energies. If LRMs are indeed realized in nature, the mediators of the new weak force can be searched for in colliders via their direct production. We recast existing experimental bounds from LHC Run 2 on the heavy LRM gauge boson masses. As a novelty, we discuss the effect of the LRM scalar content on the total width of the new gauge bosons, obtaining model-independent bounds within the specific realizations of the LRM scalar sectors analysed here. These bounds avoid the need to detail the spectrum of the scalar sector, and apply in the general case where no discrete symmetry is enforced. Moreover, we emphasize the effect of the structure of the quark right-handed mixing matrix on the charged LRM gauge boson production at LHC. We find that $W_R$ and $Z_R$ masses are constrained to lie above $2$ TeV and $4$ TeV, respectively.

hep-ph↗