arXiv subjects

Alejandro Ibarra

Publications and source records attributed to Alejandro Ibarra.

At least 37 records · Page 2Linked to original sources

arXiv2025

Probing Dark Matter Electromagnetic Properties in Direct Detection Experiments

Astronomical and cosmological observations indicate that dark matter should interact very weakly with the electromagnetic radiation. Nevertheless, the existence of such interactions is not precluded by observations nor by theoretical considerations. A promising approach to probe the dark matter electromagnetic properties is through the search of photon-mediated dark matter-nucleus interactions in direct detection experiments. In this paper we present a simple methodology to calculate the scattering rate in a direct detection experiment for given values of the dark matter electric charge, charge radius, electric- and magnetic- dipole moments and anapole moment. In our work we include contributions to the scattering from nuclear recoils and from the Migdal effect. We finally apply this formalism to determine exclusion limits on the five electromagnetic interactions using data from XENON1T, LZ, PICO-60 and DS50 experiments, and we discuss the implications for a simplified dark matter model with t-channel mediators.

hep-ph↗

arXiv2025

Asymmetric Bending Boundary Layer: the $λ$-test

We investigate the mechanics of two asymmetric ribbons bound at one end and pulled apart at the other ends. We characterize the elastic junction near the bonding and conceptualize it as a bending boundary layer. While the size of this junction decreases with the pulling force, we observe the surprising existence of the binding angle as a macroscopic signature of the bending stiffnesses. Our results thus challenge the standard assumption of neglecting bending stiffness of thin shells at large tensile loading. In addition, we show how the rotational response of the structure exhibits a non-linear and universal behavior regardless of the ratio of asymmetry. Leveraging the independence of the binding angle to the pulling force, we finally introduce the $λ$-test -- a visual measurement technique to characterize membranes through simple mechanical coupling.

cond-mat.soft↗

arXiv2024

Complete Two-loop Renormalization Group Equation of the Weinberg Operator

We calculate the renormalization group equation (RGE) of the lepton-number-violating Weinberg operator with the particle content of the Standard Model (SM), thus completing the set of two-loop RGEs of the SM effective field theory up to dimension 5. We identify new diagrams that could increase the rank of the Wilson coefficient of the Weinberg operator, and we calculate the complete two-loop RGE for the neutrino mass eigenvalues and leptonic mixing matrix. We also briefly discuss some phenomenological implications of the RGEs.

hep-ph↗

arXiv2024

Matter-antimatter asymmetry and dark matter stability from baryon number conservation

There is currently no evidence for a baryon asymmetry in our Universe. Instead, cosmological observations have only demonstrated the existence of a quark-antiquark asymmetry, which does not necessarily imply a baryon asymmetric Universe, since the baryon number of the dark sector particles is unknown. In this paper we discuss a framework where the total baryon number of the Universe is equal to zero, and where the observed quark-antiquark asymmetry arises from neutron portal interactions with a dark sector fermion $N$ that carries baryon number. In order to render a baryon symmetric universe throughout the whole cosmological history, we introduce a complex scalar $χ$, with opposite baryon number and with the same initial abundance as $N$. Notably, due to the baryon number conservation, $χ$ is absolutely stable and could have an abundance today equal to the observed dark matter abundance. Therefore, in this simple framework, the existence of a quark-antiquark asymmetry is intimately related to the existence (and the stability) of dark matter.

hep-ph↗

arXiv2024

Minimal decaying dark matter: from cosmological tensions to neutrino signatures

The invisible decay of cold dark matter into a slightly lighter dark sector particle on cosmological time-scales has been proposed as a solution to the $S_8$ tension. In this work we discuss the possible embedding of this scenario within a particle physics framework, and we investigate its phenomenology. We identify a minimal dark matter decay setup that addresses the $S_8$ tension, while avoiding the stringent constraints from indirect dark matter searches. In our scenario, the dark sector contains two singlet fermions $N_{1,2}$, quasi-degenerate in mass, and carrying lepton number so that the heaviest state ($N_2$) decays into the lightest ($N_1$) and two neutrinos via a higher-dimensional operator $N_2\to \bar N_1νν$. The conservation of lepton number, and the small phase-space available for the decay, forbids the decay channels into hadrons and strongly suppresses the decays into photons or charged leptons. We derive complementary constraints on the model parameters from neutrino detectors, freeze-in dark matter production via $νν\to N_1N_2$, collider experiments and blazar observations, and we show that the upcoming JUNO neutrino observatory could detect signals of dark matter decay for model parameters addressing the $S_8$ tension if the dark matter mass is below $\simeq 1$ GeV.

hep-ph↗

arXiv2023

Proton capture in compact dark stars and observable implications

Asymmetric dark matter under certain conditions could form compact star-like objects, which can be searched either through gravitational lensing or by observation of gravitational waves from binaries involving such compact objects. In this paper we analyze possible signatures of such dark stars made of asymmetric dark matter with a portal to the Standard Model. We argue that compact dark stars could capture protons and electrons from the interstellar medium, which then accumulate in the core of the dark star, forming a very hot gas that emits X-rays or $γ$-rays. For dark matter parameters compatible with current laboratory constraints, compact dark stars could be sufficiently luminous to be detected at the Earth as point sources in the X-ray or $γ$-ray sky.

hep-ph↗

arXiv2023

New constraints on the dark matter-neutrino and dark matter-photon scattering cross sections from TXS 0506+056

The flux of high energy neutrinos and photons produced in a blazar could get attenuated when they propagate through the dark matter spike around the central black hole and the halo of the host galaxy. Using the observation by IceCube of a few high-energy neutrino events from TXS 0506+056, and their coincident gamma ray events, we obtain new constraints on the dark matter-neutrino and dark matter-photon scattering cross sections. Our constraints are orders of magnitude more stringent than those derived from considering the attenuation through the intergalactic medium and the Milky Way dark matter halo. When the cross-section increases with energy, our constraints are also stronger than those derived from the CMB and large-scale structure.

hep-ph↗

arXiv2023

Enhanced prospects for direct detection of inelastic dark matter from a non-galactic diffuse component

In some scenarios, the dark matter particle predominantly scatters inelastically with the target, producing a heavier neutral particle in the final state. In this class of scenarios, the reach in parameter space of direct detection experiments is limited by the velocity of the dark matter particle, usually taken as the escape velocity from the Milky Way. On the other hand, it has been argued that a fraction of the dark matter particles in the Solar System could be bound to the envelope of the Local Group or to the Virgo Supercluster, and not to our Galaxy, and therefore could carry velocities larger than the escape velocity from the Milky Way. In this paper we estimate the enhancement in sensitivity of current direct detection experiments to inelastic dark matter scatterings with nucleons or electrons due to the non-galactic diffuse components, and we discuss the implications for some well motivated models.

hep-ph↗

arXiv2023

Multipole vector dark matter below the GeV-scale

We consider electrically neutral complex vector particles $V$ below the GeV mass scale that, from a low energy perspective, couple to the photon via higher dimensional form factor interactions. We derive ensuing astrophysical constraints by considering the anomalous energy loss from the Sun, Horizontal Branch, and Red Giant stars as well as from SN1987A that arise from vector pair-production in these environments. Under the assumption that the dark states $V$ constitute dark matter, the bounds are then complemented by direct and indirect detection as well as cosmological limits. The relic density from freeze-out and freeze-in mechanisms is also computed. On the basis of a UV-complete model that realizes the considered effective couplings, we also discuss the naturalness of the constrained parameter space, and provide an analysis of the zero mass limit of $V$.

hep-ph↗

arXiv2023

Primordial lepton asymmetries in the precision cosmology era: Current status and future sensitivities from BBN and the CMB

Using a new sample of extremely metal poor systems, the EMPRESS survey has recently reported a primordial helium abundance that is $3σ$ smaller than the prediction from the standard big bang nucleosynthesis (BBN) scenario. This measurement could be interpreted as a hint for a primordial lepton asymmetry in the electron neutrino flavor. Motivated by the EMPRESS results, we present a comprehensive analysis of the lepton asymmetry using measurements of the abundances of primordial elements, along with cosmic microwave background (CMB) data from Planck. Assuming that there is no dark radiation in our Universe, we find an electron neutrino chemical potential $ξ_{ν_e} = 0.043 \pm 0.015$, which deviates from zero by $2.9σ$. If no assumption is made on the abundance of dark radiation in the Universe, the chemical potential is $ξ_{ν_e} = 0.046 \pm 0.021$, which deviates from zero by $2.2σ$. We also find that this result is rather insensitive to the choice of nuclear reaction rates. If the true helium abundance corresponds to the EMPRESS central value, future CMB observations from the Simons Observatory and CMB-S4 will increase the significance for a nonzero lepton asymmetry to $4σ$ and $5σ$ respectively, assuming no dark radiation, or to $3σ$ when no assumption is made on the abundance of dark radiation.

hep-ph↗

arXiv2023

Anapole Moment of Majorana Fermions and Implications for Direct Detection of Neutralino Dark Matter

For Majorana fermions the anapole moment is the only allowed electromagnetic multipole moment. In this work we calculate the anapole moment induced at one-loop by the Yukawa and gauge interactions of a Majorana fermion, using the pinch technique to ensure the finiteness and gauge-invariance of the result. As archetypical example of a Majorana fermion, we calculate the anapole moment for the lightest neutralino in the Minimal Supersymmetric Standard Model, and specifically in the bino, wino and higgsino limits. Finally, we briefly discuss the implications of the anapole moment for the direct detection of dark matter in the form of Majorana fermions.

hep-ph↗

arXiv2022

Indirect upper limits on $\ell_i\to\ell_jγγ$ from $\ell_i\to\ell_jγ$

We perform an effective field theory analysis to correlate the charged lepton flavor violating processes $\ell_i\to\ell_jγγ$ and $\ell_i\to\ell_jγ$. Using the current upper bounds on the rate for $\ell_i\to\ell_jγ$, we derive model-independent upper limits on the rates for $\ell_i\to\ell_jγγ$. Our indirect limits are about three orders of magnitude stronger than the direct bounds from current searches for $μ\to eγγ$, and four orders of magnitude better than current bounds for $τ\to\ellγγ$. We also stress the relevance of Belle II or a Super Tau Charm Facility to discover the rare decay $τ\to\ellγγ$.

hep-ph↗

arXiv2022

Probing the Inert Doublet Dark Matter Model with Cherenkov Telescopes

We present a detailed study of the annihilation signals of the inert dark matter doublet model in its high mass regime. Concretely, we study the prospects to observe gamma-ray signals of the model in current and projected Cherenkov telescopes taking into account the Sommerfeld effect and including the contribution to the spectrum from gamma-ray lines as well as from internal bremsstrahlung. We show that present observations of the galactic center by the H.E.S.S. instrument are able to exclude regions of the parameter space that give the correct dark matter relic abundance. In particular, models with the charged and the neutral components of the inert doublet nearly degenerate in mass have strong gamma-ray signals. Furthermore, for dark matter particle masses above 1 TeV, we find that the non-observation of the continuum of photons generated by the hadronization of the annihilation products typically gives stronger constraints on the model parameters than the sharp spectral features associated to annihilation into monochromatic photons and the internal bremsstrahlung process. Lastly, we also analyze the interplay between indirect and direct detection searches for this model, concluding that the prospects for the former are more promising. In particular, we find that the upcoming Cherenkov Telescope Array will be able to probe a significant part of the high mass regime of the model.

hep-ph↗

arXiv2022

Reevaluation of the cosmic antideuteron flux from cosmic-ray interactions and from exotic sources

Cosmic-ray antideuterons could be a key for the discovery of exotic phenomena in our Galaxy, such as dark-matter annihilations or primordial black hole evaporation. Unfortunately the theoretical predictions of the antideuteron flux at Earth are plagued with uncertainties from the mechanism of antideuteron production and propagation in the Galaxy. We present the most up-to-date calculation of the antideuteron fluxes from cosmic-ray collisions with the interstellar medium and from exotic processes. We include for the first time the antideuteron inelastic interaction cross section recently measured by the ALICE collaboration to account for the loss of antideuterons during propagation. In order to bracket the uncertainty in the expected fluxes, we consider several state-of-the-art models of antideuteron production and of cosmic-ray propagation.

astro-ph.HE↗

arXiv2022

Complementarity of experiments in probing the non-relativistic effective theory of dark matter-nucleon interactions

The non-relativistic effective theory of dark matter-nucleon interactions depends on 28 coupling strengths for dark matter spin up to 1/2. Due to the vast parameter space of the effective theory, most experiments searching for dark matter interpret the results assuming that only one of the coupling strengths is non-zero. On the other hand, dark matter models generically lead in the non-relativistic limit to several interactions which interfere with one another, therefore the published limits cannot be straightforwardly applied to model predictions. We present a method to determine a rigorous upper limit on the dark matter-nucleon interaction strength including all possible interferences among operators. We illustrate the method to derive model independent upper limits on the interaction strengths from the null search results from XENON1T, PICO-60 and IceCube. For some interactions, the limits on the coupling strengths are relaxed by more than one order of magnitude. We also present a method that allows to combine the results from different experiments, thus exploiting the synergy between different targets in exploring the parameter space of dark matter-nucleon interactions.

hep-ph↗

arXiv2021

Flavor violating muon decay into an electron and a light gauge boson

We analyze the flavor violating muon decay $μ\rightarrow eχ$, where $χ$ is a massive gauge boson, with emphasis in the regime where $χ$ is ultralight. We first study this process from an effective field theory standpoint in terms of form factors. We then present two explicit models where $μ\rightarrow eχ$ is generated at tree level and at the one-loop level. We also comment on the prospects of observing the process $μ\rightarrow eχ$ in view of the current limits on $μ\rightarrow 3e$ from the SINDRUM collaboration.

hep-ph↗

arXiv2021

Direct detection of non-galactic light dark matter

A fraction of the dark matter in the solar neighborhood might be composed of non-galactic particles with speeds larger than the escape velocity of the Milky Way. The non-galactic dark matter flux would enhance the sensitivity of direct detection experiments, due to the larger momentum transfer to the target. In this note, we calculate the impact of the dark matter flux from the Local Group and the Virgo Supercluster diffuse components in nuclear and electron recoil experiments. The enhancement in the signal rate can be very significant, especially for experiments searching for dark matter induced electron recoils.

hep-ph↗

arXiv2021

Conservative constraints on the effective theory of dark matter-nucleon interactions from IceCube: the impact of operator interference

We present a method to derive conservative upper limits on the coupling constants of the effective theory of dark matter-nucleon interactions, taking into account the interference among operators. The method can be applied in any basis, and can be easily particularized to any UV complete model. To illustrate our method, we use the IceCube constraints on an exotic neutrino flux from dark matter annihilations in the Sun to derive conservative upper limits on the dark matter-nucleon coupling constants of the effective theory, as well as to derive conservative upper limits on the dark matter-proton and dark matter-neutron scattering cross-sections.

hep-ph↗