arXiv subjects

Farinaldo S. Queiroz

Publications and source records attributed to Farinaldo S. Queiroz.

At least 55 records · Page 3Linked to original sources

arXiv2019

New Physics Probes: Atomic Parity Violation, Polarized Electron Scattering and Neutrino-Nucleus Coherent Scattering

Atomic Parity Violation (APV) is usually quantified in terms of the weak nuclear charge $Q_W$ of a nucleus, which depends on the coupling strength between the atomic electrons and quarks. In this work, we review the importance of APV to probing new physics using effective field theory. Furthermore, using $SU(2)$ invariance, we correlate our findings with those from neutrino-nucleus coherent scattering. Moreover, we investigate signs of parity violation in polarized electron scattering and show how precise measurements on the Weinberg angle, $\sin θ_W$, will give rise to competitive bounds on light mediators over a wide range of masses and interactions strength. Lastly, apply our bounds to several models namely, Dark Z, Two Higgs Doublet Model-$U(1)_X$ and 3-3-1, considering both light and heavy mediator regimes.

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arXiv2019

Dark and Bright Signatures of Di-Higgs Production

If the Higgs boson decays to a pair of invisible particles, the number of di-Higgs events, where each Higgs decay into Standard Model (SM) particles, are reduced by a factor of two-third taking into account the current LHC bound on invisible decay width of the Higgs boson. We investigate the sensitivity of the upcoming high luminosity run of the LHC to di-Higgs production and subsequent decay to dark matter in the context of the singlet scalar extension of the SM augmented by a fermionic dark matter in the dark and bright channel $γγ+\not\!\! E_T$. Once systematic uncertainties on background yields are considered, this dark and bright channel presents competitive limits than $b\bar{b}+\not\!\! E_T$ after a careful tuning of the kinematical cuts that raise the signal over background ratio. We further show that in a multivariate analysis, for an invisible branching fraction as low as $\sim 10$%, we obtain stronger bounds for the Higgs trilinear coupling from the $γγ+\not\!\! E_T$ channel compared to the $b\bar{b}γγ$ final state. Finally, we demonstrate that the three channels $γγ+\not\!\! E_T$, $b\bar{b}+\not\!\! E_T$ and $b\bar{b}γγ$, complement each other in the search for di-Higgs production with non-SM trilinear couplings when an invisible decay mode is present.

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arXiv2019

Neutrino Masses in a Two Higgs Doublet Model with a U(1) Gauge Symmetry

General Two Higgs Doublet Models (2HDM) are popular Standard Model extensions but feature flavor changing interactions and lack neutrino masses. We discuss a 2HDM where neutrino masses are generated via type I seesaw and propose an extension where neutrino masses are generated via a type II seesaw mechanism with flavor changing interactions being absent via the presence of a U(1) gauge symmetry. After considering a variety of bounds such as those rising from collider and electroweak precision we show that our proposal stands as a UV complete 2HDM with a dark photon where neutrino masses and flavor changing interactions are addressed. A possible dark matter realization is also discussed.

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arXiv2019

Search for Semi-Annihilating Dark Matter with Fermi-LAT, H.E.S.S., Planck, and the Cherenkov Telescope Array

Dark matter annihilations have been fiercely restricted by the non-observation of excess events in indirect detection probes. Typically the interactions that dictate annihilation are also present in the dark matter-nucleon scattering cross section, also severely constrained by direct detection experiments. Semi-annihilations arise as a possible way to ameliorate the tension and even change the standard dark matter relic density calculation. In this work, we derive indirect detection bounds for several semi-annihilation channels including gauge bosons, the Higgs, leptophilic and leptophobic scalars. Our analysis is based on the gamma-ray observations in the direction of Dwarf Spheroidal Galaxies (Fermi-LAT) and the Galactic Center (H.E.S.S.), and Planck measurements of Cosmic Background Radiation. In addition, we derive the prospects for the Cherenkov Telescope Array (CTA) sensitivity to all these semi-annihilation modes.

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arXiv2019

Type I + II Seesaw in a Two Higgs Doublet Model

Two Higgs Doublet Models (2HDM) are popular extensions of the Standard Model for several reasons, but do not explain neutrino masses. In this work, we investigate how one can incorporate neutrino masses within the framework of the 2HDM-U(1), where U(1) is an abelian gauge symmetry used to nicely address the absence of flavor changing neutral currents in 2HDM. In particular, we explore realizations of the type I and type II seesaw since they are mechanisms that we dote on for being able to generate elegantly small active neutrino masses. We show that one can build several models featuring type I, type II and type I+II seesaw mechanism with different phenomenological implications.

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arXiv2019

Lepton Flavor Violation and Collider Searches in a Type I + II Seesaw Model

Neutrino are massless in the Standard Model. The most popular mechanism to generate neutrino masses are the type I and type II seesaw, where right-handed neutrinos and a scalar triplet are augmented to the Standard Model, respectively. In this work, we discuss a model where a type I + II seesaw mechanism naturally arises via spontaneous symmetry breaking of an enlarged gauge group. Lepton flavor violation is a common feature in such setup and for this reason, we compute the model contribution to the $μ\rightarrow eγ$ and $μ\rightarrow 3e$ decays. Moreover, we explore the connection between the neutrino mass ordering and lepton flavor violation in perspective with the LHC, HL-LHC and HE-LHC sensitivities to the doubly charged scalar stemming from the Higgs triplet. Our results explicitly show the importance of searching for signs of lepton flavor violation in collider and muon decays. The conclusion about which probe yields stronger bounds depends strongly on the mass ordering adopted, the absolute neutrino masses and which much decay one considers. In the 1-5 TeV mass region of the doubly charged scalar, lepton flavor violation experiments and colliders offer orthogonal and complementary probes. Thus if a signal is observed in one of the two new physics searches, the other will be able to assess whether it stems from a seesaw framework.

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arXiv2019

A Two Higgs Doublet Model for Dark Matter and Neutrino Masses

Motivated by the interesting features of Two Higgs Doublet Models (2HDM) we present a 2HDM extension where the stability of dark matter, neutrino masses and the absence of flavor changing interactions are explained by promoting baryon and lepton number to gauge symmetries. Neutrino masses are addressed within the usual type I seesaw mechanism. A vector-like fermion acts as dark matter and it interacts with Standard Model particles via the kinetic and mass mixings between the neutral gauge bosons. We compute the relevant observables such as the dark matter relic density and spin-independent scattering cross section to outline the region of parameter space that obeys current and projected limits from collider and direct detection experiments via thermal and non-thermal dark matter production.

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arXiv2019

Detecting Dark Matter with Neutron Star Spectroscopy

The presence of dark matter has been ascertained through a wealth of astrophysical and cosmological phenomena and its nature is a central puzzle in modern science. Elementary particles stand as the most compelling explanation. They have been intensively searched for at underground laboratories looking for an energy recoil signal and at telescopes sifting for excess events in gamma-ray or cosmic-ray observations. In this work, we investigate a detection method based on spectroscopy measurements of neutron stars. We outline the luminosity and age of neutrons stars whose dark matter scattering off neutrons can heat neutron stars up to a measurable level. We show that in this case neutron star spectroscopy could constitute the best probe for dark matter particles over a wide masses and interactions strength.

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arXiv2018

Scrutinizing Right-Handed Neutrino Portal Dark Matter With Yukawa Effect

Analyzing the neutrino Yukawa effect in the freeze-out process of a generic dark matter candidate with right-handed neutrino portal, we identify the parameter regions satisfying the observed dark matter relic density as well as the current Fermi-LAT and H.E.S.S. limits and the future CTA reach on gamma-ray signals. In this scenario the dark matter couples to the Higgs boson at one-loop level and thus could be detected by spin-independent nucleonic scattering for a reasonable range of the relevant parameters.

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arXiv2018

XENON1T Takes a Razor to a Dark $E_6$-Inspired Model

Motivated by the recent result of XENON1T collaboration with full exposure, 279 life days, that sets the most stringent limit on the spin-independent dark matter-nucleon scattering cross section we discuss a dark $E_6$-inspired model that features the presence of a $U(1)_{d-u}$ gauge symmetry. The dark matter candidate is a Dirac fermion that interacts with Standard Model fermions via a massive Z' that preserves the quantum number assignments of this symmetry. We compute the spin-independent scattering cross section off xenon nucleus and compare with the XENON1T limit; find the LHC bound on the Z' mass as well as the projection sensitivity of high-energy and luminosity LHC; and derive the Fermi-LAT bounds on the dark matter annihilation cross section based on the observation of gamma-rays in the direction of Dwarf Spheroidal galaxies. We exploit the complementarity between these datasets to conclude that the new bound from XENON1T severely constrain the model, which combined with the LHC upgrade sensitivity rules out this WIMP realization setup below 5 TeV.

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arXiv2018

Tritium beta decay with additional emission of new light bosons

We consider tritium beta decay with additional emission of light pseudoscalar or vector bosons coupling to electrons or neutrinos. The electron energy spectrum for all cases is evaluated and shown to be well estimated by approximated analytical expressions. We give the statistical sensitivity of KATRIN to the mass and coupling of the new bosons, both in the standard setup of the experiment as well as for future modifications in which the full energy spectrum of tritium decay is accessible.

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arXiv2018

Gamma-ray lines may reveal the CP nature of the dark matter particle

Determining the fundamental properties of the dark matter is one of the most important open problems in particle physics today. If the dark matter particle has spin zero, one of these properties is its CP nature. That is, whether it is CP-even (scalar), CP-odd (pseudoscalar), or if its interactions violate CP. In this paper, we show that the observation of $γ$-ray lines arising from the decay of a spin-zero dark matter particle could be used to discriminate among these possibilities. We consider a general setup where dark matter decay is induced by effective operators and demonstrate that, due to gauge invariance, there exists correlations among the branching ratios into gauge boson final states ($γγ$, $γZ$, $W^+W^-$, $ZZ$) that depend on the mass and the CP properties of the dark matter. Consequently, the future observation of $γ$-ray lines may in principle be used to establish the CP nature of the dark matter particle.

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arXiv2018

The Dark $L_μ- L_τ$ Rises via Kinetic Mixing

We investigate the dark matter phenomenology of a Dirac fermion together with kinetic mixing in the context of an $L_μ- L_τ$ model. We analyze which part of the parameter space can provide a viable dark matter candidate and explain the B-decay anomaly, while obeying current data. Although the allowed region of parameter space, satisfying these requirements, is still large at the moment, future direct detection experiments like XENONnT and DARWIN will, in case of null results, significantly strengthen the limits and push the model to a corner of the parameter space.

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arXiv2018

Collider Bounds on 2-Higgs Doublet Models with $U(1)_X$ Gauge Symmetries

2-Higgs Doublet Models (2HDMs) typically need to invoke an ad-hoc discrete symmetry to avoid severe flavor bounds and in addition feature massless neutrinos, thus falling short of naturally complying with existing data. However, when augmented by an Abelian gauge symmetry naturally incorporating neutrino masses via a type-I seesaw mechanism while at the same time escaping flavor changing interactions, such enlarged 2HDMs become very attractive phenomenologically. In such frameworks, the distinctive element is the $Z'$ gauge boson generated by the spontaneous breaking of the Abelian group $U(1)_X$. In this work, we derive updated collider bounds on it. Several theoretical setups are possible, each with different and sometimes suppressed couplings to quarks and leptons. Thus, complementary data from dijet and dilepton resonance searches need to be considered to fully probe these objects. We employ the corresponding datasets as obtained at the Large Hadron Collider (LHC) at the 13 TeV CMs energy for $\mathcal{L}=12,36$ and $300$ fb$^{-1}$ of luminosity. Moreover, we present the potential sensitivity to such $Z'$s of the High Luminosity LHC (HL-LHC) and High Energy LHC (HE-LHC).

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arXiv2018

Asymmetric Dark Matter, Inflation and Leptogenesis from B-L Symmetry Breaking

We propose a unified setup for dark matter, inflation and baryon asymmetry generation through the neutrino mass seesaw mechanism. Our scenario emerges naturally from an extended gauge group containing $B-L$ as a non-commutative symmetry, broken by a singlet scalar that also drives inflation. Its decays reheat the universe, producing the lightest right-handed neutrino. Automatic matter parity conservation leads to the stability of an asymmetric dark matter candidate, directly linked to the matter-antimatter asymmetry in the universe.

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arXiv2018

MeV Dark Matter Complementarity and the Dark Photon Portal

We discuss the phenomenology of an MeV-scale Dirac fermion coupled to the Standard Model through a dark photon with kinetic mixing with the electromagnetic field. We compute the dark matter relic density and explore the interplay of direct detection and accelerator searches for dark photons. We show that precise measurements of the temperature and polarization power spectra of the Cosmic Microwave Background Radiation lead to stringent constraints, leaving a small window for the thermal production of this MeV dark matter candidate. The forthcoming MeV gamma-ray telescope e-ASTROGAM will offer important and complementary opportunities to discover dark matter particles with masses below 10 MeV. Lastly, we discuss how a late-time inflation episode and freeze-in production could conspire to yield the correct relic density while being consistent with existing and future constraints.

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arXiv2018

Pseudoscalar Mediators: A WIMP model at the Neutrino Floor

Due to its highly suppressed cross section (fermionic) dark matter interacting with the Standard Model via pseudoscalar mediators is expected to be essentially unobservable in direct detection experiments. We consider both a simplified model and a more realistic model based on an extended two Higgs doublet model and compute the leading one-loop contribution to the effective dark matter- nucleon interaction. This higher order correction dominates the scattering rate completely and can naturally, i.e. for couplings of order one, lead to a direct detection cross section in the vicinity of the neutrino floor. Taking the observed relic density and constraints from low-energy observables into account we analyze the direct detection prospects in detail and find regions of parameter space that are within reach of upcoming direct detection experiments such as XENONnT, LZ, and DARWIN.

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arXiv2018

Neutrino-Electron Scattering: General Constraints on Z' and Dark Photon Models

We study the framework of $U(1)_X$ models with kinetic mixing and/or mass mixing terms. We give general and exact analytic formulas and derive limits on a variety of $U(1)_X$ models that induce new physics contributions to neutrino-electron scattering, taking into account interference between the new physics and Standard Model contributions. Data from TEXONO, CHARM-II and GEMMA are analyzed and shown to be complementary to each other to provide the most restrictive bounds on masses of the new vector bosons. In particular, we demonstrate the validity of our results to dark photon-like as well as light $Z^\prime$ models.

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