arXiv subjects

P. M. Ferreira

Publications and source records attributed to P. M. Ferreira.

At least 19 recordsLinked to original sources

arXiv2026

Imaginary scaling invariance of the one-loop effective potential

Recently, a hitherto unknown class of renormalization group stable relations between parameters of bosonic field theories have been identified and dubbed as the r0 or 'GOOFy' symmetries. Here, one-loop properties of the r0 invariant two-Higgs Doublet Model and a minimal symmetric model are discussed. It is concluded that the symmetry is present at the one-loop provided the UV cutoff squared transforms non-trivially under r0. The minimal model requires the presence of two real fields.

hep-ph↗

arXiv2026

GOOFy fermions

A new class of symmetries of two Higgs doublet models was recently discovered, the result of an unorthodox transformation on scalar and gauge fields and spacetime coordinates. It was explicitly shown that it is possible to choose Yukawa matrix textures which respect those symmetries up to two-loops. In this work we will establish the fermion field transformations for the two Higgs doublet models to be considered in the context of the new symmetries established. New regions of parameter space, invariant under renormalization to all orders of perturbation theory, are discovered, including scalar-fermion interactions.

hep-ph↗

arXiv2026

Pseudoscalar contributions to Zh production at the LHC at 95 GeV and above

In generalizations of the Standard Models with extended scalar sectors, pseudoscalar particles will contribute to associated production of the Higgs boson discovered at the LHC, $h$, and the $Z$ boson. The pseudoscalar can be produced via gluon-gluon fusion, and as such may give contributions to $Zh$ production comparable to the value predicted by the Standard Model. We analyze this possibility in two different models, the Two Higgs Doublet Model, with and without an added complex singlet scalar, computing both the total and differential cross sections for this process. We focus on two pseudoscalar mass regions: (i) $m_A \sim 95$ GeV, to describe the di-photon excesses observed by CMS and ATLAS; (ii) 100 GeV $ \le m_A \le $ 1000 GeV, as a generic heavier pseudoscalar. A pseudoscalar with $m_A \sim 95$ GeV tends to give a contribution to the $pp \to Zh$ cross section that is too small to set new limits on the parameter spaces of the two models. Heavier pseudoscalars, on the other hand, can yield cross-section contributions larger than allowed by current LHC measurements and thus restricting regions of parameter space of these models which are in agreement with theoretical and all other experimental constraints. The increase of LHC luminosity will yield even substantially tighter constraints.

hep-ph↗

arXiv2026

RG-stable parameter relations of a scalar field theory in absence of a symmetry

The stability of tree-level relations among the parameters of a quantum field theory with respect to renormalization group (RG) running is typically explained by the existence of a symmetry. We examine a toy model of a quantum field theory of two real scalars in which a tree-level relation among the squared-mass parameters of the scalar potential appears to be RG-stable without the presence of an appropriate underlying symmetry. The stability of this relation with respect to renormalization group running can be explained by complexifying the original scalar field theory. It is then possible to exhibit a symmetry that guarantees the relations of relevant beta functions of squared-mass parameters of the complexified theory. Among these relations, we can identify equations that are algebraically identical to the corresponding equations that guarantee the stability of the relations among the squared-mass parameters of the original real scalar field theory where the symmetry of the complexified theory is no longer present.

hep-ph↗

arXiv2025

One-loop pseudoscalar mass in a 2HDM with a $Z_3$ symmetry

A two-Higgs doublet model with a discrete $Z_3$ symmetry acquires, in its scalar and gauge sectors, an accidental continuous $U(1)$ symmetry. One therefore finds, after spontaneous symmetry breaking of those symmetries, that a massless pseudoscalar arises, as expected by Goldstone's theorem. In the fermion sector, however, it is possible to obtain Yukawa matrix textures which distinguish between the $Z_3$ and $U(1)$ symmetries, so one expects loop corrections to originate a non-zero pseudoscalar mass for the $Z_3$ case. We perform an explicit calculation that shows that at one-loop the pseudoscalar remains massless for all but one tested $Z_3$ Yukawa matrices. The pseudoscalar mass thus found is highly suppressed by the hierarchy of fermion masses.

hep-ph↗

arXiv2023

A closer look at the $U(1)_{B-L}$ explanation of the ATOMKI nuclear anomalies

We revisit the gauged $U(1)_{B-L}$ explanation of the ATOMKI nuclear anomalies, in which the new gauge boson is the hypothetical $X(17)$ particle. It is known that the vanilla $B-L$ scenario is unable to account for appropriate couplings, namely the suppression of the couplings of $X(17)$ to neutrinos, which motivates adding vector-like leptons. The simplest case, in which the new fields have $B-L$ charges equal to $1$, is highly disfavoured since it requires large mixing with the Standard Model fields. One solution recently put forward is to consider large $B-L$ charges to counterbalance small mixing. We show that, in this scenario, and after taking into account several phenomenological constraints, the dominant contribution to the muon anomalous magnetic moment $(g-2)_μ$ is expected to be extremely large and with a negative sign, being thus excluded by experiment.

hep-ph↗

arXiv2023

2HDM interpretations of the CMS diphoton excess at 95 GeV

In both Run 1 and Run 2 of the LHC, the CMS collaboration has observed an excess of events in the searches for low-mass Higgs bosons in the diphoton final state at a mass of about 95 GeV. After a recent update of the experimental analysis, in which the full Run 2 data collected at 13 TeV has been included and an improved experimental calibration has been applied, the local significance of the excess amounts to $2.9σ$. The presence of this diphoton excess is especially interesting in view of a further excess observed by CMS in ditau final states at a comparable mass and similar local significance. Moreover, an excess of events with about $2σ$ local significance and consistent with a mass of 95 GeV was observed in LEP searches for a Higgs boson decaying to pairs of bottom quarks. We interpret the CMS diphoton excess in combination with the ditau excess in terms of a pseudoscalar resonance in the CP-conserving two-Higgs-doublet model (2HDM). Furthermore, we discuss the possibility that, if CP-violation is taken into account, a CP-mixed scalar state can in addition describe the LEP result, thus accommodating all three excesses simultaneously. We find that the region of parameter space where both the CMS diphoton and ditau excesses can be fitted is in tension with current constraints from the flavour sector, potentially calling for other new-physics contributions to flavour-physics observables, most notably $b \to sγ$ transitions. We also comment on the compatibility with the recent ATLAS di-photon searches.

hep-ph↗

arXiv2022

Preserving the validity of the Two-Higgs Doublet Model up to the Planck scale

We examine the constraints on the two Higgs doublet model (2HDM) due to the stability of the scalar potential and absence of Landau poles at energy scales below the Planck scale. We employ the most general 2HDM that incorporates an approximately Standard Model (SM) Higgs boson with a flavor aligned Yukawa sector to eliminate potential tree-level Higgs-mediated flavor changing neutral currents. Using basis independent techniques, we exhibit robust regimes of the 2HDM parameter space with a 125 GeV SM-like Higgs boson that is stable and perturbative up to the Planck scale. Implications for the heavy scalar spectrum are exhibited.

hep-ph↗

arXiv2022

The hidden side of scalar-triplet models with spontaneous CP violation

Scalar triplet extensions of the Standard Model provide an interesting playground for the explanation of neutrino mass suppression through the type-II seesaw mechanism. Propelled by the possible connections with leptonic CP violation, we explore under which conditions spontaneous CP violation can arise in models with extra scalar triplets. The minimal model satisfying such conditions requires adding two such triplets to the SM field content. For this model, the scalar mass spectrum in both the CP-conserving and spontaneous CP-violating scenarios is studied. In the former case, a decoupling limit for the new scalars can be achieved, while this is not the case when CP is spontaneously broken. In particular, we show that the existence of two light neutral scalars with masses below a few tenths of GeVs is unavoidable in the CP-violating case. Using matrix theory theorems, we derive upper bounds for the masses of those light scalars and briefly examine whether they can still be experimentally viable. Other interesting features of the scalar mass spectrum are discussed as, e.g., the existence of relations among the charged and neutral scalar masses.

hep-ph↗

arXiv2021

A three Higgs doublet model with symmetry-suppressed flavour changing neutral currents

We construct a three-Higgs doublet model with a flavour non-universal ${\rm U}(1)\times \mathbb{Z}_2$ symmetry. That symmetry induces suppressed flavour-changing interactions mediated by neutral scalars. New scalars with masses below the TeV scale can still successfully negotiate the constraints arising from flavour data. Such a model can thus encourage direct searches for extra Higgs bosons in the future collider experiments, and includes a non-trivial flavour structure.

hep-ph↗

arXiv2021

$(g-2)_μ$ in the 2HDM and slightly beyond -- an updated view

The recent measurement of the muon $g - 2$ anomaly continues to defy a Standard Model explanation, but can be accommodated within the framework of two Higgs doublet models. If one further includes extra fermion content in the form of a generation of vector like leptons, the allowed parameter range that explains the anomaly is even further extended, and thorny issues of perturbativity and clashes with $B$-decay constraints avoided. We will show how the muon magnetic moment anomaly can be fit within these models, under the assumption that the vector-like leptons do not mix with the muon. We update previous analyses and include all theoretical and experimental constraints, including searches for extra scalars. It is shown that the inclusion of vector-like fermions allows the lepton-specific and muon-specific models to perform much better in fitting the muon's $g - 2$. These fits do require the Yukawa coupling between the Higgs and the vector-like leptons to be large, causing potential problems with perturbativity and unitarity, and thus models in which the vector-like leptons mix with the muon may be preferred.

hep-ph↗

arXiv2021

Symmetries of the 2HDM: an invariant formulation and consequences

Symmetries of the Two-Higgs-Doublet Model (2HDM) potential that can be extended to the whole Lagrangian, i.e. the CP-symmetries CP1, CP2, CP3 and the Higgs-family symmetries Z2, U(1) and SO(3) are discussed. Sufficient and necessary conditions in terms of constraints on masses and physical couplings for the potential to respect each of these symmetries are found. Each symmetry can be realized through several alternative cases, each case being a set of relations among physical parameters. We will show that some of those relations are invariant under the renormalization group, but others are not. The cases corresponding to each symmetry group are illustrated by analyzing the interplay between the potential and the vacuum expectation values.

hep-ph↗

arXiv2020

Radiative seesaw corrections and charged-lepton decays in a model with soft flavour violation

We consider the one-loop radiative corrections to the light-neutrino mass matrix and their consequences for the predicted branching ratios of the five lepton-flavour-violating decays $\ell_1^- \to \ell_2^- \ell_3^+ \ell_3^-$ in a two-Higgs-doublet model furnished with the type-I seesaw mechanism and soft lepton-flavour violation. We find that the radiative corrections are very significant; they may alter the predicted branching ratios by several orders of magnitude and, in particular, they may help explain why $\mbox{BR}(μ^- \to e^- e^+ e^-)$ is strongly suppressed relative to the branching ratios of the decays of the $τ^-$. We conclude that, in any serious numerical assessment of the predictions of this model, it is absolutely necessary to take into account the one-loop radiative corrections to the light-neutrino mass matrix.

hep-ph↗

arXiv2020

Suppression of the Higgs Dimuon Decay

It is often stated that elimination of tree-level flavor-changing neutral currents in multi-Higgs models requires that all fermions of a given charge to couple to the same Higgs boson. A counterexample was provided by Abe, Sato and Yagyu in a muon-specific two-Higgs doublet model with a softly-broken $Z_4$ symmetry. In this model, all fermions except the muon couple to one Higgs and the muon couples to the other. We study the phenomenology of the model and show that there is a wide range of parameter-space in which the branching ratios of the 125 GeV Higgs are very close to their Standard Model values, with the exception of the branching ratio into muons, which can be substantially suppressed -- this is an interesting possibility, since the current value of this branching ratio is $0.5 \pm 0.7$ times the Standard Model value. We also study the charged Higgs boson and show that, if it is lighter than $200$ GeV, it could have a large branching ratio into $μν$ - even substantially larger than the usual decay into $τν$. The decays of the heavy neutral scalars are also studied. The model does have a relationship between the branching ratios of the 125 GeV Higgs into $Z$'s, $τ$'s and $μ$'s, which can be tested in future accelerators.

hep-ph↗

arXiv2020

Stability of neutral minima against charge breaking in the Higgs triplet model

We analyse the possibility of charge breaking minima developing in the Higgs triplet model, and under what conditions they are deeper than charge-preserving ones. Analytical expressions relating the depth of minima of different types are deduced. A global symmetry of the model leads to increased stability for charge-preserving vacua. However, if that symmetry is broken by a soft term, deeper charge-breaking minima may occur more easily. We identify the vev configurations most likely to produce charge breaking minima.

hep-ph↗

arXiv2019

No strong $CP$ violation up to the one-loop level in a two-Higgs-doublet model

We put forward a two-Higgs-doublet model, furnished with a $Z_3$ symmetry, wherein $CP$ is conserved in the dimension-four terms of the Lagrangian and is softly broken in the scalar potential. The new particles of our model are one neutral scalar $H$, one neutral pseudoscalar $A$, and two charged scalars $H^\pm$. In our model the only locus of $CP$ violation is the CKM matrix. Strong $CP$ violation is absent both at the tree and one-loop levels. We work out the phenomenological constraints on our model, which features flavour-changing neutral Yukawa interactions, showing that the new scalar particles may in some cases be lighter than 500\,GeV.

hep-ph↗

arXiv2019

Vacuum Instabilities in the N2HDM

The Higgs sector of the Next-to-Minimal Two-Higgs-Doublet Model (N2HDM) is obtained from the Two-Higgs-Doublet Model (2HDM) containing two complex Higgs doublets, by adding a real singlet field. In this paper, we analyse the vacuum structure of the N2HDM with respect to the possibility of vacuum instabilities. We show that while one type of charge- and CP-preserving vacuum cannot coexist with deeper charge- or CP-breaking minima, there is another type of vacuum whose stability is endangered by the possible occurrence of deeper charge- and CP-breaking minima. Analytical expressions relating the depth of different vacua are deduced. Parameter scans of the model are carried out that illustrate the regions of parameter space here the vacuum is either stable or metastable as well as the regions where tunnelling to deeper vacua gives rise to a too short lifetime of the vacuum. Taking other experimental and theoretical constraints into account, we find that the vacuum stability constraints have an important impact on the phenomenology of the N2HDM.

hep-ph↗

arXiv2018

Electroweak vacuum lifetime in two Higgs doublet models

We study the stability of neutral electroweak vacua in two Higgs doublet models, and calculate the lifetime of these states when the parameters are such that they are false vacua. As the two Higgs doublet model is invariant under a sign change of both doublets, degenerate true vacua exist. It is shown that this degeneracy, despite the fact that each of these minima locally describes the same physics, can immensely affect their lifetime. We apply these calculations to the parameter space of the models which is allowed by recent LHC searches, and infer combinations of parameters which should be excluded on grounds of a tunneling time inferior to the age of the universe.

hep-ph↗