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Donini, A., Folgado, M. G., Herrero-Garcia, J., Landini, G., Muñoz-Ovalle, A., & Rius, N. (2025). Dark Matter in an evanescent three-brane Randall-Sundrum scenario. J. High Energy Phys., 11(11), 037–42pp.
Abstract: Apart from its gravitational interactions, dark matter (DM) has remained so far elusive in laboratory searches. One possible explanation is that the relevant interactions to explain its relic abundance are mainly gravitational. In this work we consider an extra-dimensional Randall-Sundrum scenario with a TeV-PeV IR brane, where the Standard Model is located, and a GeV-TeV deep IR (DIR) one, where the DM lies. When the curvatures of the bulk to the left and right of the IR brane are very similar, the tension of the IR brane is significantly smaller than that of the other two branes, and therefore we term it “evanescent”. In this setup, the relic abundance of DM arises from the freeze-out mechanism, thanks to DM annihilations into radions and gravitons. Focusing on a scalar singlet DM candidate, we compute and apply current and future constraints from direct, indirect and collider-based searches. Our findings demonstrate the viability of this scenario and highlight its potential testability in upcoming experiments. We also discuss the possibility of inferring the number of branes if the radion and several Kaluza-Klein graviton resonances are detected at a future collider.
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Navarro-Madrid, J. R., Reina-Valero, J., Diaz-Morcillo, A., & Gimeno, B. (2025). Enhancement of dark photon haloscope sensitivity with degenerate modes: Toward axion-level form factor and polarization determination. Phys. Rev. D, 112(10), 103029–13pp.
Abstract: The dark photon has been postulated as a potential constituent of dark matter, exhibiting notable similarities to the axion. The primary distinction between the two particles lies in the nature of their respective fields: the dark photon field is a vector field with a polarization direction that remains undetermined. This work explores the prospect of utilizing three degenerate modes for scanning the three dimensions of space in order to mitigate the low form factor expected in the detection of the dark photon due to their unknown polarization. The employment of a haloscope with three orthogonal and degenerate modes in conjunction with the coherent sum of signals is demonstrated in this work in order to enhance the dark photon form factor up to the axion form factor, and to determine the direction of the dark photon polarization vector. We show in this manuscript that the maximum form factor is achieved in cavities of cubic, spherical, and cylindrical geometries, considering the introduction of tuning elements. To achieve this adequately, some conditions reviewed in this article must be fulfilled in the resonant cavity, leading to uncertainties in the final measurement. Finally, this technique can allow the simultaneous search for dark matter axions and dark photons, and to the knowledge of the authors, the method shown in this work is the most effective one for detecting dark photons with microwave resonant cavities.
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Giare, W., Mena, O., Specogna, E., & Di Valentino, E. (2025). Neutrino mass tension or suppressed growth rate of matter perturbations? Phys. Rev. D, 112(10), 103520–19pp.
Abstract: Assuming a minimal A cold dark matter (ACDM) cosmology with three massive neutrinos, the joint analysis of Planck cosmic microwave background data, DESI baryon acoustic oscillations, and distance moduli measurements of type Ia supernovae from the Pantheon + sample sets an upper bound on the total neutrino mass, Sigma m(nu)less than or similar to 0.06-0.07 eV, that lies barely above the lower limit from oscillation experiments. These constraints are mainly driven by mild differences in the inferred values of the matter density parameter across different probes that can be alleviated by introducing additional background-level degrees of freedom (e.g., by dynamical dark energy models). However, in this work, we explore an alternative possibility. Since both Omega(m) and massive neutrinos critically influence the growth of cosmic structures, we test whether the neutrino mass tension may originate from the way matter clusters, rather than from a breakdown of the ACDM expansion history. To this end, we introduce the growth index gamma, which characterizes the rate at which matter perturbations grow. Deviations from the standard ACDM value (gamma similar or equal to 0.55) can capture a broad class of models, including nonminimal dark sector physics and modified gravity. We show that allowing gamma to vary significantly relaxes the neutrino mass bounds to Sigma m(nu)less than or similar to 0.13-0.2 eV, removing any tension with terrestrial constraints without altering the inferred value of 1m. However, this comes at the cost of departing from standard growth predictions: to have Sigma m(nu)less than or similar to 0.06 eV, one needs gamma > 0.55, and we find a consistent preference for gamma > 0.55 at the level of similar to 26. This preference increases to similar to 2.5-36 when a physically motivated prior Sigma m(nu)>= 0.06 eV from oscillation experiments is imposed.
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Farakos, K., Koutsoumbas, G., Mavromatos, N. E., & Zarafonitis, A. (2025). On internal mechanical properties of electroweak magnetic monopoles and their effects on stability. Eur. Phys. J.-Spec. Top., , 53pp.
Abstract: By considering properties of the energy-momentum tensor of the electroweak magnetic monopole and its Born-Infeld extension, we attempt to make comments on the stability of these configurations. Specifically, we perform a study of the behaviour of the so-called internal force and pressure of these extended field-theoretic solitonic objects, which are derived from the energy-momentum tensor. Our method is slightly different from the so-called Laue's criterion for stability of nuclear matter, a local form of which had been proposed and applied in the earlier literature to the 't Hooft-Polyakov (HP) magnetic monopole, and found to be violated. By applying our method first to HP monopole, we also observe that, despite its topological stability, the total (finite) internal force (which has only radial components) is directed inwards, towards the centre of the monopole, which would imply instability. Thus this mechanical criterion for stability is arguably violated in the case of the HP monopole, as is the local version of Laue's criterion. The criterion is satisfied for the short-range part of the energy momentum tensor, in which the long-range part, due to the massless photon of the U(1) subgroup, is subtracted. This makes the HP monopole mechanically stable by our criterion, which is also confirmed due to its proven topological stability. Par contrast, the total internal force of the Cho-Maison (CM) electroweak monopole has both radial and angular components, which diverge at the origin, leading to rotational instabilities, violating the short-range Laue's criterion for stability. Finally, by studying extensions of the CM, in which the latter is embedded in theories with non-minimal couplings of the hypercharge and Higgs sectors, as well as higher-derivative electromagnetic interactions of Born-Infeld type, we find that the total force, integrated over space, is finite, but, in the Born-Infeld case it has also angular components. The latter feature is interpreted as indicating that, unlike the rest of the CM extensions, the Born-Infeld-CM monopole might be subject to rotations upon the action of perturbations, but this does not necessarily imply mechanical instabilities of the configuration. For such unstable composite monopoles, one expects a decay after production into charged constituent W +/-\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$W<^>\pm$$\end{document} bosons, which are in principle detectable at colliders.
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Miramontes, A. S., Papavassiliou, J., & Pawlowski, J. M. (2025). Electromagnetic properties of heavy-light mesons. Eur. Phys. J. C, 85(12), 1390–16pp.
Abstract: Within the Bethe-Salpeter framework, we present a computation of space-like electromagnetic form factors for pseudoscalar mesons, including light and heavy-light systems. Our approach employs a flavour-dependent variation of the standard Taylor effective charge, which contains key contributions from the quark-gluon vertices. This effective interaction is a common ingredient of all relevant dynamical equations, and accommodates the crucial mass differences between the various quark flavours. Particular attention is paid to the nonperturbative determination of the quark-photon vertex. The computed electromagnetic form factors for the pion and the kaon mesons show excellent agreement with experimental determinations. In addition, the predictions for the charge radii of heavy-light systems are in overall good agreement with lattice QCD.
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