arXiv subjects

Alejandro de la Puente

Publications and source records attributed to Alejandro de la Puente.

At least 19 recordsLinked to original sources

arXiv2019

Mono-Higgs Signature in the Scotogenic Model with Majorana Dark Matter

We study the phenomenology of scotogenic model in the case of Majorana Dark Matter (DM) candidate. This scenario gives important consequences since the parameter space of the model is almost unconstrained compared to the Inert Higgs Doublet Model (or the scotogenic model with scalar DM), and hence, offers new opportunities for discovery at future high energy collider, e.g. the HL-LHC. As an example, we focus on the production of the Standard Model (SM) Higgs boson in association with a pair of dark scalars. Owing to its clean signature, the $γγ$ decay channel of the SM Higgs boson is investigated in great detail at both the HL-LHC (at $\sqrt{s}=14$ TeV) and the future FCC-hh (at $\sqrt{s}=100$ TeV). After revisiting the LHC constraints from run-II on the parameter space of the model, and selecting benchmark points satisfying all the theoretical and experimental constraints, we found that scalars with mass up to $140$ GeV ($160$ GeV) can be probed at the LHC (FCC-hh) with a $3$ ab$^{-1}$ of integrated luminosity assuming $5\%$ of uncertainty.

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arXiv2016

Implications of a Electroweak Triplet Scalar Leptoquark on the Ultra-High Energy Neutrino Events at IceCube

We study the production of scalar leptoquarks at IceCube, in particular, a particle transforming as a triplet under the weak interaction. The existence of electroweak-triplet scalars is highly motivated by models of grand unification and also within radiative seesaw models for neutrino mass generation. In our framework, we extend the Standard Model by a single colored electroweak-triplet scalar leptoquark and analyze its implications on the excess of ultra-high energy neutrino events observed by the IceCube collaboration. We consider only couplings between the leptoquark to first generation leptons and quarks and carry out a statistical analysis to determine the parameters that best describe the IceCube data as well as set $95\%$ CL upper bounds. We analyze whether this study is still consistent with most up-to-date LHC data and various low energy observables.

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arXiv2016

Breakdown of Effective Field Theory for a Gluon Initiated Resonance

Gauge invariance dictates that a resonance produced from initial state gluons must be produced through a non-renormalizable operator or a loop process. Should such a resonance be discovered, uncovering the dynamics that give rise to its couplings to gluons will be crucial to understanding the nature of the new state. Here we study how the production of this resonance at high transverse momentum in association with one (or more) jets can be used to directly measure the scale of the operator or the mass of the particles in the loop. We use a 750 GeV diphoton resonance as an example application, and we study how the non-renormalizable operator case can be described by a slowly converging effective field theory (EFT) expansion with operators of dimension five and seven. We show that with O(100) events, one can put strong constraints on the scale of the EFT, particularly in theories with strong coupling. We also compare the EFT analysis to that of a UV completion with vector-like quarks, and outline how the mass of said quarks could be measured.

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arXiv2016

The Dilaton-like Higgs boson with scalar singlet dark matter

We study a model with a Higgs-like dilaton and a Standard Model gauge-singlet scalar dark matter candidate. We begin by updating the status of identifying the observed 125 GeV Higgs-like boson with the pseudo Nambu-Goldstone boson that arises from the spontaneous breaking of scale invariance using recent Higgs boson signal strength measurements by the ATLAS and CMS collaborations. We then constrain the extended model with recent constraints on the Higgs invisible width, the observed dark matter relic abundance and the latest dark matter direct detection limits. We found that the magnitude of the dilaton-$γγ$ and dilaton-glue-glue coupling is constrained to be close to the standard model values. The mass of the dark matter candidate is contrained to be greater than half the dilaton mass by relic abundance limits and Higgs invisible width limits. Dark matter direct detection limits allow only small mass regions which will be further constrained by upcoming DEAP measurements.

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arXiv2016

Electroweak Vacuum Stability and the Seesaw Mechanism Revisited

We study the electroweak vacuum stability in Type I seesaw models for 3 generations of neutrinos in scenarios where the right-handed neutrinos have explicit bare mass terms in the Lagrangian and where these are dynamically generated through the mechanism of spontaneous symmetry breaking. To best highlight the difference of the two cases we concentrate on the absolute stability of the scalar potential. We observe that for the first scenario, the scale at which the scalar potential becomes unstable is lower from that within the Standard Model. In addition the Yukawa couplings $\mathbf{Y}_ν$ are constrained such that $\Tr{[\mathbf{Y}^{\dagger}_ν\mathbf{Y}_ν}] \lesssim10^{-3}$. In the second scenario the electroweak stability can be improved in a large region of parameter space. However, we found that the scalar used to break the lepton number symmetry cannot be too light and have a large coupling to right-handed neutrinos in order for the seesaw mechanism to be a valid mechanism for neutrino mass generation. In this case we have $\Tr [\mathbf{Y}^\dagger_ν \mathbf{Y}_ν]\lesssim 0.01$.

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arXiv2016

Compressing the Inert Doublet Model

The Inert Doublet Model relies on a discrete symmetry to prevent couplings of the new scalars to Standard Model fermions. This stabilizes the lightest inert state, which can then contribute to the observed dark matter density. In the presence of additional approximate symmetries, the resulting spectrum of exotic scalars can be compressed. Here, we study the phenomenological and cosmological implications of this scenario. We derive new limits on the compressed Inert Doublet Model from LEP, and outline the prospects for exclusion and discovery of this model at dark matter experiments, the LHC, and future colliders.

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arXiv2016

Long-lived Colored Scalars at the LHC

We study the collider signatures of a long-lived massive colored scalar transforming trivially under the weak interaction and decaying within the inner sections of a detector such as ATLAS or CMS. In our study, we assume that the colored scalar couples at tree-level to a top quark and a stable fermion, possibly arising from a dark sector or from supersymmetric extensions of the Standard Model. After implementing the latest experimental searches for long-lived colored scalars, we observe a region of parameter space consistent with a colored electroweak-singlet scalar with mass between $\sim200-350$ GeV and a lifetime between $0.1-1$ $\text{mm}/c$ together, with a nearly degenerate dark fermion that may be probed at the $\sqrt{s}=13$ TeV LHC. We show that a search strategy using a combination of cuts on missing transverse energy and impact parameters can exclude regions of parameter space not accessed by prompt searches. We show that a region of parameter space within our simplified model may naturally arise from the light-stop window regime of supersymmetric extensions of the Standard Model, where a light mostly right-handed stop has a mass slightly larger than the lightest neutralino and decays through a four-body process.

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arXiv2015

Search for Heavy Right-Handed Neutrinos at the LHC and Beyond in the Same-Sign Same-Flavor Leptons Final State

In this study we explore the LHC's Run II potential to the discovery of heavy Majorana neutrinos, with luminosities between $30$ and $3000$ fb$^{-1}$ in the $l^{\pm}l^{\pm}j~j$ final state. Given that there exist many models for neutrino mass generation, even within the Type I seesaw framework, we use a simplified model approach and study two simple extensions to the Standard Model, one with a single heavy Majorana neutrino, singlet under the Standard Model gauge group, and a limiting case of the left-right symmetric model. We then extend the analysis to a future hadron collider running at $100$ TeV center of mass energies. This extrapolation in energy allows us to study the relative importance of the resonant production versus gauge boson fusion processes in the study of Majorana neutrinos at hadron colliders. We analyze and propose different search strategies designed to maximize the discovery potential in either the resonant production or the gauge boson fusion modes.

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arXiv2014

Probing Radiative Neutrino Mass Generation through Monotop Production

We present a generalization of a model where the right-handed up-type quarks serve as messengers for neutrino mass generation and as a portal for dark matter. Within this framework the Standard Model is extended with a single Majorana neutrino, a coloured electroweak-singlet scalar and a coloured electroweak-triplet scalar. We calculate the relic abundance of dark matter and show that we can match the latest experimental results. Furthermore, the implications from the scattering between nuclei and the dark matter candidate are studied and we implement the latest experimental constraints arising from flavour changing interactions, Higgs production and decay and LHC collider searches for a single jet and jets plus missing energy. In addition, we implement constraints arising from scalar top quark pair-production. We also study the production of a single top in association with missing energy and calculate the sensitivity of the LHC to the top quark semileptonic decay mode with the current $20$ fb$^{-1}$ data set at a centre of mass energy of $\sqrt{s}=8$ TeV. Furthermore, we carry out the analysis to centre of mass energies of $\sqrt{s}=14$ TeV with $30$ and $300$ fb$^{-1}$ of data.

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arXiv2014

Vector-like quarks with a scalar triplet

We study a minimal extension to the Standard Model with an additional real scalar triplet, $Σ$, and a single vector-like quark, $T$. This class of models appear naturally in extensions of the Littlest Higgs model that incorporate dark matter without the need of $T$-parity. We assume the limit that the triplet does not develop a vacuum expectation value and that all dimension five operators coupling the triplet to Standard Model fields and the vector-like quarks are characterized by the scale $Λ$ at which we expect new physics to arise. We introduce new non-renormalizable interactions between the new scalar sector and fermion sector that allow mixing between the Standard Model third generation up-type quark and the vector-like quark in a way that leads to the cancellation of the leading quadratic divergences to the one-loop corrections from the top quark to the mass of the Higgs boson. Within this framework, new decay modes of the vector-like quark to the real scalar triplet and SM particles arise and bring forth an opportunity to probe this model with existing and future LHC data. We contrast constraints from direct colliders searches with low energy precision measurements and find that heavy vector-like top quarks with a mass as low as $650$ GeV are consistent with current experimental constraints in models where new physics arises at scales below $2$ TeV.

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arXiv2014

Manifestations of Warped Extra Dimension in Rare Charm Decays and Asymmetries

We study the effects of models with a warped extra dimension on rare charm decays. While the new degrees of freedom in these models are bounded above a few TeV, they can leave signatures in rare charm decays with their tiny Standard Model background. We look at several channels with leptons in the final state along with several asymmetries of both kinematical and dynamical nature. CPT invariance is `usable' for analyzing the impacts of new dynamics in $D$ meson decays and in particular, rare decays of charm mesons.

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arXiv2013

Darkening the Little Higgs

We present a novel new method for incorporating dark matter into little Higgs models in a way that can be applied to many existing models without introducing T-parity, while simultaneously alleviating precision constraints arising from heavy gauge bosons. The low energy scalar potential of these dark little Higgs models is similar to, and can draw upon existing phenomenological studies of, inert doublet models. Furthermore, we apply this method to modify the littlest Higgs model to create the next to littlest Higgs model, and describe details of the dark matter candidate and its contribution to the relic density.

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arXiv2013

Top Quark as a Dark Portal and Neutrino Mass Generation

We present a new model for radiatively generating Majorana active neutrino masses while incorporating a viable dark matter candidate. This is possible by extending the Standard Model with a single Majorana neutrino endowed with a dark parity, a colour electroweak singlet scalar, as well as a colour electroweak triplet scalar. Within this framework, the $up$-type quarks play a special role, serving as a portal for dark matter, and a messenger for neutrino mass generation. We consider three benchmark scenarios where the abundance of dark matter can match the latest experimental results, while generating neutrino masses in the milli-electronvolt range. We show how constraints from lepton flavour violation, in particular the branching fraction of $μ\to eγ$, can place lower bounds on the coupling between our dark matter candidate and top quarks. Furthermore, we show that this coupling can also be constrained using collider data from the Tevatron and the LHC.

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arXiv2012

LHC Signals of Non-Custodial Warped 5D Models

We study the implications at the LHC for a recent class of non-custodial warped extra-dimensional models where the AdS_5 metric is modified near the infrared brane. Such models allow for TeV Kaluza-Klein excitations without conflict with electroweak precision tests. We discuss both the production of electroweak and strong Kaluza-Klein gauge bosons. As we will show, only signals involving the third generation of quarks seem to be feasible in order to probe this scenario.

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arXiv2011

Signals of CP Violation Beyond the MSSM in Higgs and Flavor Physics

We study an extension of the Higgs sector of the Minimal Supersymmetric Standard Model (MSSM), considering the effects of new degrees of freedom at the TeV scale, and allowing for sources of CP violation beyond the MSSM (BMSSM). We analyze the impact of the BMSSM sources of CP violation on the Higgs collider phenomenology and on low energy flavor and CP violating observables. We identify distinct Higgs collider signatures that cannot be realized, either in the case without CP violating phases or in the CP violating MSSM, and investigate the prospects to probe them at the Tevatron and the LHC. The most striking benchmark scenario has three neutral Higgs bosons that all decay dominantly into W boson pairs and that are well within the reach of the 7 TeV LHC run. On the other hand, we also present scenarios with three Higgs bosons that have masses M_Hi > 150 GeV and decay dominantly into b bbar. Such scenarios are much more challenging to probe and can even lie completely outside the reach of the 7 TeV LHC run. We explore complementary scenarios with standard MSSM Higgs signals that allow to accommodate a sizable B_s mixing phase as indicated by D0, as well as the excess in B_s --> mu+ mu- candidates recently reported by CDF. We find that, in contrast to the MSSM, a minimal flavor violating soft sector is sufficient to generate significant corrections to CP violating observables in meson mixing, compatible with EDM constraints. In particular, a sizable B_s mixing phase, S_psiphi < 0.4, can be achieved for specific regions of parameter space. Such a large B_s mixing phase would unambiguously imply a sizable suppression of S_psiKs with respect to the SM prediction and a BR(B_s --> mu+ mu-) close to the 95% C.L. upper bound reported by CDF.

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arXiv2011

The Forward-Backward Top Asymmetry in a Singlet extension of the MSSM

The CDF and D0 collaborations have recently reported a large forward-backward asymmetry in the ttbar system which deviates from the next to-leading order QCD standard model prediction. We study the asymmetry in the ttbar system within the framework of singlet extensions of the Minimal Supersymmetric Standard Model. For this purpose, we introduce non-renormalizable couplings between first and third generation of quarks to scalars. We analyze two limiting cases of the model, characterized by the size of the supersymmetric mass for the singlet superfield. We study both the small and large limits of this mass parameter. We find that in the region of small singlet supersymmetric mass we can obtain a large asymmetry while being consistent with limits on the ttbar production cross section. These results are also consistent with constraints arising from flavor physics, quark masses and top quark decays.

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arXiv2011

Solving the Hierarchy Problem with a Light Singlet and Supersymmetric Mass Terms

A generalization of the Next-to-Minimal Supersymmetric Model (NMSSM) is studied in which an explicit μ-term as well as a small supersymmetric mass term for the singlet superfield are incorporated. We study the possibility of raising the Standard Model-like Higgs mass at tree level through its mixing with a light, mostly-singlet, CP-even scalar. We are able to generate Higgs boson masses up to 145 GeV with top squarks below 1.1 TeV and without the need to fine tune parameters in the scalar potential. This model yields light singlet-like scalars and pseudoscalars passing all collider constraints.

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arXiv2010

A Gauge-Mediated Embedding of the S-MSSM

We embed the S-MSSM -- a singlet extension of the minimal supersymmetric standard model with an explicit mu-term and supersymmetric mass term -- in a gauge-mediated supersymmetry breaking scheme. We find that by absolving the singlet of its responsibility for solving the mu-problem, we are instead able to solve the little hierarchy problem naturally. Specifically, we find that even with a minimal embedding of the S-MSSM into a gauge-mediated scheme, we can easily raise the lightest Higgs mass above 114 GeV, while keeping top squarks below the TeV scale, maintaining perturbative unification of the gauge couplings, and without tuning the other parameters of the model.

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