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Grinstein, B., Lu, X. C., Miro, C., & Quílez, P. (2025). Most general EFTs from spurion analysis Hilbert series and minimal lepton flavor violation. J. High Energy Phys., 07(7), 259–41pp.
Abstract: We derive a saturation theorem for general Effective Field Theories (EFTs) constructed using spurion analysis. Let S be a set of spurion fields introduced to organize the breaking of a global symmetry Gf, and HS be the subgroup of Gf that remains unbroken under a generic vacuum expectation value < S >; we show that the EFT Lagrangian constructed from the spurion analysis saturates the EFT Lagrangian without the spurions but restricted to HS invariance, provided that arbitrary powers of the spurion fields are allowed. As examples, we study several implementations of the Minimal Lepton Flavor Violation (MLFV) principle, corresponding to various origins of the neutrino masses. In each scenario, we compute the Hilbert series to obtain the numbers of independent lepton flavor covariants that appear in the corresponding EFT at mass dimension 6. These numbers agree with the number of HS invariants in the EFT without the spurions, demonstrating the saturation theorem. Motivated by phenomenological connections, we provide linearly independent spurion polynomials for selected lepton flavor covariants. A supplementary material file supplies , a Mathematica notebook that provides functions for computing general Hilbert series of invariants and covariants of compact classical groups. It presents examples demonstrating the use of the code, including the Hilbert series for our MLFV scenarios.
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De Romeri, V., Donato, F., Maurin, D., Stefanuto, L., & Tolino, A. (2025). Antinuclei from primordial black holes. Phys. Rev. D, 112(2), 023003–16pp.
Abstract: Light primordial black holes (PBHs) may have originated in the early Universe, and could contribute to the dark matter in the Universe. Their Hawking evaporation into particles could eventually lead to the production of antinuclei, which propagate and arrive at Earth as cosmic rays with a flux peaked at GeV energies. We revisit here the antiproton and antideuteron signatures from PBH evaporation, relying on a lognormal PBH mass distribution, state-of-the-art propagation models, and an improved coalescence model for fusion into antideuterons. Our predictions are then compared with AntiMatter Spectrometer (AMS)-02 data on the antiproton flux. We find that the AMS-02 antiproton data severely constrain the Galactic PBH density, setting bounds that depend significantly on the parameters of the lognormal mass distribution, and that are comparable to or slightly stronger than bounds set from diverse messengers. We also discuss prospects for future detection of antideuterons. Given the bounds from AMS-02 antiproton data, we predict that if antideuterons were to be measured by AMS-02 or General Antiparticle Spectrometer, since the secondary contribution is subdominant, they would clearly be a signal of new physics, only part of which could, however, be explained by PBH evaporation.
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Caprini, C., Jinno, R., Konstandin, T., Pol, A. R., Rubira, H., & Stomberg, I. (2025). Gravitational waves from first-order phase transitions: from weak to strong. J. High Energy Phys., 07(7), 217–69pp.
Abstract: We study the generation of gravitational waves (GWs) during a cosmological first-order phase transition (PT) using the recently introduced Higgsless approach to numerically simulate the fluid motion induced by the PT. We present for the first time GW spectra sourced by bulk fluid motion in the aftermath of strong first-order PTs (alpha = 0.5), alongside weak (alpha = 0.0046) and intermediate (alpha = 0.05) PTs, previously considered in the literature. We find that, for intermediate and strong PTs, the kinetic energy in our simulations decays, following a power law in time. The decay is potentially determined by non-linear dynamics and hence related to the production of vorticity. We show that the assumption that the source is stationary in time, characteristic of compressional motion in the linear regime (sound waves), agrees with our numerical results for weak PTs, since in this case the kinetic energy does not decay with time. We then provide a theoretical framework that extends the stationary assumption to one that accounts for the time evolution of the source: as a result, the GW energy density is no longer linearly increasing with the source duration, but proportional to the integral over time of the squared kinetic energy fraction. This effectively reduces the linear growth rate of the GW energy density and allows to account for the period of transition from the linear to the non-linear regimes of the fluid perturbations. We validate the novel theoretical model with the results of simulations and provide templates for the GW spectrum for a broad range of PT parameters.
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Peñalver, D., De Vito, M., Balbinot, R., & Fabbri, A. (2025). Acoustic black holes in BECs with an extended sonic region. Phys. Rev. D, 112(2), L021701–5pp.
Abstract: In the context of Hawking-like radiation in sonic black holes formed by Bose-Einstein condensates we investigate the modifications of the emission spectrum caused by a finite width of the sonic transition region connecting the subsonic to supersonic flow.
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Salor-Iguiñiz, N., Benlloch-Rodriguez, J. M., Esteve, R., Alvarez, V., Ballester, F., Gadea, R., et al. (2025). Evaluation of coincidence time resolution in a liquid xenon detector with silicon photomultipliers. Phys. Rev. Res., 7(3), 033089–9pp.
Abstract: This work explores the combination of liquid xenon as a scintillating medium and silicon photomultipliers as a readout in Positron Emission Tomography (PET) for enhanced Time-Of-Flight resolution. We present the results of our first prototype optimized to maximize light collection using high photodetection efficiency (PDE), VUV-sensitive sensors and to minimize time fluctuations. We report a coincidence time resolution of 281 +/- 2 ps FWHM, obtained using a 22Na calibration source. This result is competitive with the current state-of-the-art PET scanners and represents a significant step forward in the development of liquid xenon as a viable alternative to conventional scintillators in PET technology.
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