arXiv subjects

Maíra Dutra

Publications and source records attributed to Maíra Dutra.

15 recordsLinked to original sources

arXiv2026

Constraining light dark matter in vector-scalar portals with COSI and AMEGO-X

Detecting gamma-ray signals that could be due to dark matter (DM) particles would give us invaluable information about the nature of DM. In particular, gamma-ray lines could provide a way to measure the DM mass. The excellent energy resolution of the upcoming Compton Spectrometer and Imager (COSI) will allow us to probe underexplored regions of the DM parameter space while being sensitive to distinctive spectral features of potential DM signals. In this work, we consider a fermionic sub-GeV DM charged under a new U(1) gauge symmetry. Both the DM and the new gauge boson $Z'$ acquire mass from a new singlet scalar. The masses of the new particles in this class of vector-scalar portal models are naturally at the MeV scale, enabling detectable gamma-ray lines in the bandpasses of COSI and proposed missions such as the All-sky Medium Energy Gamma-ray Observatory eXplorer (AMEGO-X). We estimate the sensitivities of COSI and AMEGO-X to sub-GeV DM in this context, considering a B-L and a purely axial $Z'$ as benchmark examples. We find regions of the parameter space where COSI will provide leading constraints, beyond the strong CMB limits. On the other hand, AMEGO-X would probe most of the viable parameter space leading to continuum gamma rays. The implementation of our generic vector-scalar portal model in the Hazma toolkit is available at GitHub.

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arXiv2024

The Waning of the WIMP: Endgame?

Weakly Interacting Massive Particles (WIMPs) continue to be considered some of the best-motivated Dark Matter (DM) candidates. No conclusive signal, despite an extensive search program that combines, often in a complementary way, direct, indirect, and collider probes, has been however detected so far. This situation might change in the near future with the advent of even larger, multi-ton Direct Detection experiments. We provide here an updated review of the WIMP paradigm, with a focus on selected models that can be probed with upcoming facilities, all relying on the standard freeze-out paradigm for the relic density. We also discuss Collider and Indirect Searches when they provide complementary experimental information.

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arXiv2023

Snowmass2021 Cosmic Frontier White Paper: Ultraheavy particle dark matter

We outline the unique opportunities and challenges in the search for "ultraheavy" dark matter candidates with masses between roughly $10~{\rm TeV}$ and the Planck scale $m_{\rm pl} \approx 10^{16}~{\rm TeV}$. This mass range presents a wide and relatively unexplored dark matter parameter space, with a rich space of possible models and cosmic histories. We emphasize that both current detectors and new, targeted search techniques, via both direct and indirect detection, are poised to contribute to searches for ultraheavy particle dark matter in the coming decade. We highlight the need for new developments in this space, including new analyses of current and imminent direct and indirect experiments targeting ultraheavy dark matter and development of new, ultra-sensitive detector technologies like next-generation liquid noble detectors, neutrino experiments, and specialized quantum sensing techniques.

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arXiv2023

Probing feebly interacting dark matter with monojet searches

Dark matter may consist of feebly interacting massive particles (FIMPs) that never thermalized with the cosmic plasma. Their relic density is achieved via freeze-in for a wide range of masses, significantly expanding the model space that can be tested compared to other production mechanisms. However, testing the tiny couplings required by freeze-in is challenging. We show that FIMPs can be probed by LHC searches for new physics in mono-jet events with large missing energy. We study a $Z'$ portal model in which gluon annihilation produces FIMPs in the early universe and today at colliders. Monojet searches by LHC Run 3 might discover new physics accounted for by FIMPs with mass in the MeV-TeV range.

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arXiv2023

EvoEMD: cosmic evolution with an early matter-dominated era

We present EvoEMD, a framework to calculate the evolution of cosmic relics in a Universe with an early matter-dominated (EMD) era. There are mainly two aspects to consider in this regard. First, an EMD era changes the Hubble expansion rate with respect to the standard radiation-dominated (RD) universe. Second, when the EMD era ends, the out-of-equilibrium decay of the dominant matter component may reheat the thermal bath and dilute cosmic relics. We briefly introduce the cosmology with an EMD era, and present how it is implemented in the EvoEMD framework. Users can study the coupled evolution of different interacting species in an EMD or RD universe. Two important cosmic relics are dark matter and a net lepton number. In order to show the capabilities of EvoEMD, we include simple examples of dark matter produced via freeze-out and freeze-in, and also of leptogenesis. Moreover, users can modify the model files in order to explore different new physics scenarios. EvoEMD is hosted on Github at \url{https://github.com/ycwu1030/EvoEMD}.

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arXiv2021

A model for mixed warm and hot right-handed neutrino dark matter

We discuss a model where a mixed warm and hot keV neutrino dark matter rises naturally. We arrange active and sterile neutrinos in the same $SU(3)_L$ multiplet, with the lightest sterile neutrino being dark matter. The other two heavy sterile neutrinos, through their out-of-equilibrium decay, contribute both to the dilution of dark matter density and its population, after freeze-out. We show that this model features all ingredients to overcome the overproduction of keV neutrino dark matter, and explore the phenomenological implications for Big Bang Nucleosynthesis and the number of relativistic degrees of freedom.

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arXiv2021

Testing freeze-in with axial and vector $Z'$ bosons

The freeze-in production of Feebly Interacting Massive Particle (FIMP) dark matter in the early universe is an appealing alternative to the well-known - and constrained - Weakly Interacting Massive Particle (WIMP) paradigm. Although challenging, the phenomenology of FIMP dark matter has been receiving growing attention and is possible in a few scenarios. In this work, we contribute to this endeavor by considering a $Z^\prime$ portal to fermionic dark matter, with the $Z^\prime$ having both vector and axial couplings and a mass ranging from MeV up to PeV. We evaluate the bounds on both freeze-in and freeze-out from direct detection, atomic parity violation, leptonic anomalous magnetic moments, neutrino-electron scattering, collider, and beam dump experiments. We show that FIMPs can already be tested by most of these experiments in a complementary way, whereas WIMPs are especially viable in the $Z^\prime$ low mass regime, in addition to the $Z^\prime$ resonance region. We also discuss the role of the axial couplings of $Z^\prime$ in our results. We therefore hope to motivate specific realizations of this model in the context of FIMPs, as well as searches for these elusive dark matter candidates.

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arXiv2020

Neutrino Portal to FIMP Dark Matter with an Early Matter Era

We study the freeze-in production of Feebly Interacting Massive Particle (FIMP) dark matter candidates through a neutrino portal. We consider a hidden sector comprised of a fermion and a complex scalar, with the lightest one regarded as a FIMP candidate. We implement the Type-I Seesaw mechanism for generating the masses of the Standard Model (SM) neutrinos and consider three heavy neutrinos, responsible for mediating the interactions between the hidden and the SM sectors. We assume that an early matter-dominated era (EMDE) took place for some period between inflation and Big Bang Nucleosynthesis, making the Universe to expand faster than in the standard radiation-dominated era. In this case, the hidden and SM sectors are easily decoupled and larger couplings between FIMPs and SM particles are needed from the relic density constraints. In this context, we discuss the dynamics of dark matter throughout the modified cosmic history, evaluate the relevant constraints of the model and discuss the consequences of the duration of the EMDE for the dark matter production. Finally, we show that if the heavy neutrinos are not part of the thermal bath, this scenario becomes testable through indirect detection searches.

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arXiv2019

Freeze-in production of dark matter through spin-1 and spin-2 portals

In this conference, I have talked about two scenarios in which the out-of-equilibrium production of dark matter (DM) particles in the early universe is unavoidable. In the first one \cite{bhattacharyya_freezing-dark_2018}, we extend the standard model (SM) of particle physics by an extra $U(1)$ gauge group under which all the SM particles are neutral. We then consider DM candidates interacting only with the new spin-1 gauge boson, a heavy $Z^\prime$. We assume the presence of heavy beyond the SM fermions charged under both extra $U(1)$ and SM $SU(3)_c$, allowing for a feeble connection between DM and gluons. In the second scenario \cite{bernal_spin-2_2018}, we assume that the interactions between DM and SM particles are only mediated by gravitons and massive spin-2 fields, being therefore suppressed by the Planck and some intermediate scales, respectively. In both models, we show that the SM particles are able to produce the right amount of DM candidates via freeze-in at most in the early stages of the radiation era, for DM mass in the range $10^{-3}-10^{14}$ GeV. We have shown that if heavy mediators were produced on-shell within a period of entropy production in the early universe, as in the post-inflationary reheating, the DM relic density may be enhanced by many orders of magnitude relative to the usual instantaneous reheating approximation.

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arXiv2019

The moduli portal to dark matter particles

The out-of-equilibrium production of dark matter (DM) from standard model (SM) species in the early universe (freeze-in mechanism) is expected in many scenarios in which very heavy beyond the SM fields act as mediators. In this conference, I have talked about the freeze-in of scalar, fermionic and vector DM though the exchange of moduli fields \cite{chowdhury_moduli_2019}, which are in the low-energy spectrum of many extra-dimensions and string theory frameworks. We have shown that the high-temperature dependencies of the production rate densities in this model, as well as the possibility of having moduli masses at the post-inflationary reheating scale, make it crucial to consider the contribution of the freeze-in prior the start of the standard radiation era for a correct prediction of the DM relic density.

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arXiv2018

Moduli Portal Dark Matter

We show that moduli fields as mediators between the Standard Model and the dark sector can naturally lead to the observed relic abundance. Indeed, even if moduli are very massive, the nature of their couplings with matter and gauge fields allows producing a sufficiently large amount of dark matter in the early Universe through the freeze-in mechanism. Moreover, the complex nature of the moduli fields whose real and imaginary part couple differently to the thermal bath gives an interesting and unusual phenomenology compared to other freeze-in models of that type.

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arXiv2018

Freezing-in dark matter through a heavy invisible $Z'$

We demonstrate that in a class of the $U(1)'$ extension of the Standard Model (SM), under which all the Standard Model matter fields are uncharged and the additional neutral gauge boson $Z'$ couples to a set of heavy nonstandard fermions, dark matter (DM) production mediated by $Z'$ can proceed through the generation of generalized Chern-Simons (GCS) couplings. The origin of the GCS terms is intimately connected to the cancellation of gauge anomalies. We show that the DM production cross section triggered by GCS couplings is sufficient even for an intermediate scale $Z'$ . A large range of DM and Z masses is then allowed for reasonably high reheating temperature ($T_\rh \gtrsim 10^{10}~\text{GeV}$). This type of scenario opens up a new paradigm for unified models. We also study the UV completion of such effective field theory constructions, augmenting it by a heavy fermionic spectrum. The latter, when integrated out, generates the GCS-like terms and provides a new portal to the dark sector. The presence of a number of derivative couplings in the GCS-like operators induces a high temperature dependence to the DM production rate. The mechanism has novel consequences and leads to a new reheating dependence of the relic abundance.

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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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arXiv2017

The Waning of the WIMP? A Review of Models, Searches, and Constraints

Weakly Interacting Massive Particles (WIMPs) are among the best-motivated dark matter candidates. In light of no conclusive detection signal yet despite an extensive search program that combines, often in a complementary way, direct, indirect, and collider probes, we find it timely to give a broad overview of the WIMP paradigm. In particular, we review here the theoretical foundations of the WIMP paradigm, discuss status and prospects of various detection strategies, and explore future experimental challenges and opportunities.

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arXiv2015

Majorana Dark Matter in Minimal Higgs Portal Models after LUX

We consider the Singlet Majorana fermion dark matter model, in which the standard model particles interact with the dark sector through the mixing of a singlet scalar and the Higgs boson. In this model both the dark matter and the singlet scalar carry lepton number, the latter being a bilepton. We suppose the existence of a $Z_2$ symmetry, remnant of some high energy local symmetry breaking, that stabilizes the Majorana fermion. We analyzed the parameter space of this model and found that the lepton number symmetry breaking scale, drove by the singlet scalar, is constrained to be within hundreds to thousands of GeV, so as to conform with the observed dark matter relic density. Finally, we address the direct detection and invisible Higgs decay complementarity, confronting our model with recent LUX and LHC constraints, as well as XENON1T prospects.

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