arXiv subjects

Alfonso R. Zerwekh

Publications and source records attributed to Alfonso R. Zerwekh.

At least 19 recordsLinked to original sources

arXiv2026

Vector Dark Matter in the Fundamental Representation of $SU(2)_{L}$: Sommerfeld Enhancement and Indirect Detection

In this work, we study an extension of the Standard Model that includes a new massive vector field in the fundamental representation of $SU(2)_{L}$. The neutral component of this field provides a natural dark matter candidate. We compute the annihilation cross-section including Sommerfeld enhancement and the gamma-ray flux arising from dark matter annihilation. We derive constraints on the model parameter space using current gamma-ray observations and investigate the prospects for future searches. We find that the model exhibits resonances for dark matter masses in the range $2-10$ TeV, whose properties are influenced by the value of the Higgs portal coupling. We show that part of the remaining parameter space can be probed by CTA in the near future.

hep-ph↗

arXiv2024

Mono-Higgs and Mono-$Z$ Production in the Minimal Vector Dark Matter Model

The Minimal Vector Dark Matter is a viable realization of the minimal dark matter paradigm. It extends the Standard Model by the inclusion of a vector matter field in the adjoint representation of $SU (2)_L$. The dark matter candidate corresponds to the neutral component of the new vector field ($V^0$). Previous studies have shown that the model can explain the observed dark matter abundance while evading direct and indirect searches. At colliders, the attention has been put on the production of the charged companions of the dark matter candidate. In this work, we focus on the mono-Higgs and mono-$Z$ signals at hadron colliders. The new charged vectors ($V^{\pm}$) are invisible unless a dedicated search is performed. Consequently, we assume that the mono-Higgs and mono-$Z$ processes correspond the $pp\rightarrow h V^{+,0} V^{-,0}$ and $pp\rightarrow Z V^{+,0} V^{-,0}$ reactions, respectively. We show that, while the $p p \rightarrow h V^{+,0} V^{-,0}$ is more important, both channels may produce significant signals at the HL-LHC and colliders running at $\sqrt{s} = 27$ TeV and $100$ TeV, probing almost the complete parameter space.

hep-ph↗

arXiv2024

Fermion Dark Matter in the Vector Scotogenic Model: A Survey of Signatures

In this work, we have studied the Vector Scotogenic Model in the context of the Dark Matter problem. Due to unitarity considerations, we have focused on the scenario with fermion dark matter, finding out that co-annihilations play a fundamental role in achieving dark matter relic abundance. Moreover, the coannihilation effects allow to separate the parameter space into two regions with different phenomenology. In addition, we have studied the detection prospects of these regions separately, focusing on signatures that can appear in lepton flavor violating decays, indirect and direct searches, and the production of these new particles at collider facilities.

hep-ph↗

arXiv2024

Introducing Model Benchmark Analysis for dark matter models with isomorphic lagrangians

In this work, we propose a novel approach to particle physics phenomenology, which we dubbed as model benchmark analysis. We consider models that provide vertices with similar topology but different Lorentz and gauge structure, which we call isomorphic models. Under this setup, the coupling constants for each theory have the same meaning, in the sense that describe the topologically equivalent diagrams. Consequently, each model acts like a map of parameter space into the observable space. This definition allows to group isomorphic models into families with a common parameter space and perform calculations for each model. As a proof of concept, we obtained some guidelines for the search of leptophilic dark fermions at CLIC, making predictions oriented to discriminate between beyond the standard model scenarios in light of possible signals of new physics that could appear at lepton colliders. We present different observables that can be useful to help discriminating between models.

hep-ph↗

arXiv2023

Probing Left-handed Heavy Neutral Leptons in the Vector Scotogenic Model

In this work, we consider an extension to the Standard Model composed by a Massive Vector Doublet under SU(2)$_L$ and a Left-handed Heavy Neutral Lepton. We study the production of these exotic leptons with the Same Flavor Opposite Sign standard lepton pair, and jets, considering Drell-Yan and Vector Boson Fusion as independent cases. We find that for the latter, the dilepton angular distribution is different enough from the background to use it as a smoking-gun for our model. Based on this fact, we establish limits on the parameter space considering previous experimental searches in this final state.

hep-ph↗

arXiv2022

Polynomial affine model of gravity in three-dimensions

In this work, we explore a three-dimensional formulation of the polynomial affine model of gravity, which is a model that extends general relativity by relaxing the equivalence principle through the exclusion of the metric from the set of fundamental fields. In particular, in an attempt to gain insight of the role of the torsion and nonmetricity in the gravitational models, we consider homogeneous and isotropic cosmological models, for which their solutions are classified in a \emph{decisions tree}. We also show a few of these explicit solutions that allow the definition of (alternative/emergent) metrics derived from the connection.

gr-qc↗

arXiv2021

Fermion Singlet Dark Matter in a Pseudoscalar Dark Matter Portal

We explore a simple extension to the Standard Model containing two gauge singlets: a Dirac fermion and a real pseudoscalar. In some regions of the parameter space both singlets are stable without the necessity of additional symmetries, then becoming a possible two-component dark matter model. We study the relic abundance production via freeze-out, with the latter determined by annihilations, conversions and semi-annihilations. Experimental constraints from invisible Higgs decay, dark matter relic abundance and direct/indirect detection are studied. We found three viable regions of the parameter space, and the model is sensitive to indirect searches.

hep-ph↗

arXiv2021

Aspects of the polynomial affine model of gravity in three dimensions

The polynomial affine gravity is a model that is built up without the explicit use of a metric tensor field. In this article we reformulate the three-dimensional model and, given the decomposition of the affine connection, we analyse the consistently truncated sectors. Using the cosmological ansatz for the connection, we scan the cosmological solutions on the truncated sectors. We discuss the emergence of different kinds of metrics.

gr-qc↗

arXiv2020

Minimal Spin-one Isotriplet Dark Matter

In this work we present a simple extension of the Standard Model that contains, as the only new physics component, a massive spin-one matter field in the adjoint representation of $SU(2)_{L}$. In order to be consistent with perturbative unitarity, the vector field must be odd under a $Z_{2}$ symmetry. Radiative corrections make the neutral component of the triplet ($V^{0}$) slightly lighter than the charged ones. We show that $V^{0}$ can be the dark matter particle while satisfying all current bounds if it has a mass between $2.8$ and $3.8$ TeV. We present the current limit on the model parameter space from highly complementary experimental constraints including dark matter relic density measurement, dark matter direct and indirect detection searches, LHC data on Higgs couplings to photons and LHC data on disappearing track searches. We show that the two-dimensional parameter space can be substantially covered by disappearing track searches at a future 100 TeV hadron collider, which will probe DM mass upto about 1.2 TeV.

hep-ph↗

arXiv2019

Emergent metric and geodesic analysis in cosmological solutions of (torsion-free) Polynomial Affine Gravity

Starting from an affinely connected space, we consider a model of gravity whose fundamental field is the connection. We build up the action using as sole premise the invariance under diffeomorphisms, and study the consequences of a cosmological ansatz for the affine connection in the torsion-free sector. Although the model is built without requiring a metric, we show that the nondegenerated Ricci curvature of the affine connection can be interpreted as an \emph{emergent} metric on the manifold. We show that there exists a parametrization in which the $(r,φ)$-restriction of the geodesics coincides with that of the Friedman--Robertson--Walker model. Additionally, for connections with nondegenerated Ricci we are able to distinguish between space-, time- and null-like self-parallel curves, providing a way to differentiate \emph{trajectories} of massive and massless particles.

gr-qc↗

arXiv2019

A Dark Vector Resonance at CLIC

One of the main problems in Particle Physics is to understand the origin and nature of Dark Matter. An exciting possibility is to consider that the Dark Matter belongs to a new complex but hidden sector. In this paper, we assume the existence of a strongly interacting dark sector consisting on a new scalar doublet and new vector resonances, in concordance with a model recently proposed by our group. Since in a previous work it was found that it is very challenging to find the new vector resonances at the LHC, here we study the possibility of finding them at the a future Compact Linear Collider (CLIC) running at $\sqrt{s}=3$ TeV. We consider two distinct scenarios: when the non-standard scalars are heavy, the dark resonance is intense enough to make its discovery possible at CLIC when the resonance mass is in the range $[2000,3000]$ GeV. In the second scenario, when the non-standard scalars are light, the new vector boson is too broad to be recognized as a resonance and is not detectable except when the mass of the scalars is close to (but smaller than) a half of the resonance mass and the scale of the dark sector is high. In all the positive cases, less than a tenth of the maximum integrated luminosity is needed to reach the discovery level. Finally, we also comment about the mono-$Z$ production.

hep-ph↗

arXiv2018

Dark Matter from a Vector Field in the Fundamental Representation of $SU(2)_L$

We explore an extension to the Standard Model which incorporates a vector field in the fundamental representation of $SU(2)_L$ as the only non-standard degree of freedom. This kind of field may appear in different scenarios such as Compositness, Gauge-Higgs unification and extradimensional scenarios. We study the model in which a $Z_2$ symmetry is manifest, making the neutral CP-even component of the new vector field a vectorial dark matter candidate. We constraint the parameter space through LEP and LHC data, as well as from current dark matter searches. Additionally, comment on the implications of perturbative unitarity are presented. We find that the model is highly constrained but a small region of the parameter space can provide a viable DM candidate. On the other hand, unitarity demands an UV completion at an scale below 10 TeV. Finally we contrast our predictions on mono-jet, -$Z$, -Higgs production with the ones obtained in the inert Two Higgs Doublet Model.

hep-ph↗

arXiv2018

The Linear BESS Model at the LHC

In this work we consider the Linear BESS model at the LHC. This model can be seen as an adequate benchmark for exploring the phenomenological consequences of a composite Higgs sector since its particle content is the one we would expect in a realistic low energy description of modern (Technicolor inspired) dynamical electroweak symmetry breaking scenarios. Additionally, the model exhibits the property of decoupling, producing a good ultraviolet behavior. We focus on the limits on the masses of the new heavy vector particles imposed by direct resonance searches, recent measurements of the decay of the Higgs boson into two photons and the electroweak precision tests. We found that the model is capable to accommodate the existing experimental constrains provided that the spin-1 resonances are heavier than 3.4 TeV.

hep-ph↗

arXiv2017

Corrections to (pseudo)scalars decay into a fermion pair from gravitational torsion

We study the contribution of the torsion-descendent four-fermion contact interaction to the decay width of a neutral (pseudo)scalar field into a fermion pair. This new interaction comes from the existence of gravitational torsion in models with extra dimensions. Additionally, we exemplify the formalism with two examples: first, the variation of the considered branching ratio of the Higgs in the context of the standard model, and second the proper variations of the scalar and pseudo scalar fields of the type II-1 two Higgs doublets model.

hep-ph↗

arXiv2017

An i2HDM Strongly Coupled to a non-Abelian Vector Resonance

We study the possibility of a Dark Matter candidate having its origin in an extended Higgs sector which, at least partially, is related to a new strongly interacting sector. More concretely, we consider an i2HDM (i.e. a Type-I Two Higgs Doublet Model supplemented with a Z_2 under which the non-standard scalar doublet is odd) based on the gauge group SU(2)_1 x SU(2)_2 x U(1)_Y. We assume that one of the scalar doublets and the standard fermion transform non-trivially under SU(2)_1 while the second doublet transforms under SU(2)_2. Our main hypothesis is that standard sector is weakly coupled while the gauge interactions associated to the second group is characterized by a large coupling constant. We explore the consequences of this construction for the phenomenology of the Dark Matter candidate and we show that the presence of the new vector resonance reduces the relic density saturation region, compared to the usual i2DHM, in the high Dark Matter mass range. In the collider side, we argue that the mono-Z production is the channel which offers the best chances to manifest the presence of the new vector field. We study the departures from the usual i2HDM predictions and show that the discovery of the heavy vector at the LHC is challenging even in the mono-$Z$ channel since the typical cross sections are of the order of 10^{-2} fb.

hep-ph↗

arXiv2016

On infrared problems of effective Lagrangians of massive spin 2 fields coupled to gauge fields

In this paper we analyze the interactions of a massive spin-2 particles charged under both Abelian and non-Abelian group using the Porrati-Rahman Lagrangian. This theory is valid up to an intrinsic cutoff scale. Phenomenologically a theory valid up to a cutoff scale is sensible as all known higher spin particles are non-fundamental and it is shown that indeed this action can be used to estimate some relevant cross section. Such action necessarily includes Stuckelberg field and therefore it is necessary to fix the corresponding gauge symmetry. We show that this theory, when the Stuckelberg symmetry is gauge-fixed, possesses a non-trivial infrared problem. A gauge fixing ambiguity arises which is akin to the Gribov problem in QCD in the Abelian case as well. In some cases (such as when the space-time is the four-dimensional torus) the vacuum copies can be found analytically. A similar phenomenon also appears in the case of Proca fields. A very interesting feature of these copies is that they arise only for "large enough" gauge potentials. This opens the possibility to avoid the appearance of such gauge fixing ambiguities by using a Gribov-Zwanziger like approach.

hep-th↗

arXiv2015

Composite Resonances effects on EWPT and Higgs diphoton decay rate

In scenarios of strongly coupled electroweak symmetry breaking, heavy composite particles of different spin and parity may arise and cause observable effects on signals that appear at loop levels. The recently observed process of Higgs to $γγ$ at the LHC is one of such signals. We study the new constraints that are imposed on composite models from $H\to γγ$, together with the existing constraints from the high precision electroweak tests. We use an effective chiral Lagrangian to describe the effective theory that contains the Standard Model spectrum and the extra composites below the electroweak scale. Considering the effective theory cutoff at $Λ= 4πv \sim 3 $ TeV, consistency with the $T$ and $S$ parameters and the newly observed $H\to γγ$ can be found for a rather restricted range of masses of vector and axial-vector composites from $1.5$ TeV to $1.7$ TeV and $1.8$ TeV to $1.9$ TeV, respectively, and only provided a non-standard kinetic mixing between the $W^{3}$ and $B^{0}$ fields is included.

hep-ph↗

arXiv2015

Higgs boson coupling to a new strongly interacting sector

In the framework of strongly interacting dynamics for electroweak symmetry breaking, heavy composite particles may arise and cause observable effects, as they should couple strongly to the resulting Higgs boson and affect the signals that appear at one loop level. Here we study this expected behavior, contrasting it with current experimental knowledge. We work in a simple and generic scenario where the lowest lying composite states are the Higgs scalar doublet and a massive vector triplet. We use an effective chiral Lagrangian to describe the theory below the compositeness scale $Λ$, assumed to be $4πv \simeq~3$ TeV. The effective theory contains the Standard Model spectrum and the extra composites. We determine the constraints on this scenario imposed by our current knowledge of the $Zb\bar{b}$ vertex, the $T$ and $S$ oblique parameters, and the recently measured Higgs mass and its diphoton decay rate. We found that the $T$ and $S$ parameters as well as the Higgs diphoton decay do not provide important constraints on the model. In contrast, the constraints arising from the $Zb\bar{b}$ vertex and from the Higgs mass at $126$ GeV are fulfilled only if the heavy vector resonances do not couple strongly with quarks, and at the same time the Higgs boson has a moderate but not too strong coupling to the heavy composite resonances.

hep-ph↗