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Shergold, J. D., & Spinrath, M. (2025). Constraining neutrino charges at beam experiments. Phys. Rev. D, 112(7), 073006–8pp.
Abstract: We propose a new method to constrain neutrino charges at neutrino beam experiments. Uncharged in the Standard Model, evidence for a neutrino electric charge would be a smoking gun for new physics, shedding light on the Dirac or Majorana nature of neutrinos, and giving insight into the origin of charge quantization. We find that using the most sensitive magnetometers available, existing beam experiments could constrain neutrino charges |q(nu)|less than or similar to 10(-13), in units of the electron charge, while future upgrades could strengthen these bounds significantly. We also discuss electromagnetic dipole moments and show that our proposal is highly sensitive to new long-range forces.
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Calibbi, L., Hagedorn, C., Schmidt, M. A., & Vandeleur, J. (2025). Selection rules for charged lepton flavor violating processes from residual flavor groups. Phys. Rev. D, 112(7), 075031–20pp.
Abstract: We systematically investigate the possible phenomenological impact of residual flavor groups in the charged lepton sector. We consider all possible flavor charge assignments for Abelian residual symmetries up to Z8. The allowed flavor structures of operators in Standard Model effective field theory (up to dimension six) lead to distinctive and observable patterns of charged lepton flavor violating processes. We illustrate the relevance of such selection rules displaying the current bounds on and the future sensitivities to the new physics scale. These results demonstrate, in particular, the importance and discriminating power of searches for lepton flavor violating tau lepton decays and muonium to antimuonium conversion.
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Martinez de Lejarza, J. J., Wu, H. Y., Kyriienko, O., Rodrigo, G., & Grossi, M. (2025). Quantum Chebyshev probabilistic models for fragmentation functions. Commun. Phys., 8(1), 448–9pp.
Abstract: Quantum generative modeling is emerging as a powerful tool for advancing data analysis in high-energy physics, where complex multivariate distributions are common. However, efficiently learning and sampling these distributions remains challenging. We propose a quantum protocol for a bivariate probabilistic model based on shifted Chebyshev polynomials, trained as a circuit-based representation of two correlated variables, with sampling performed via quantum Chebyshev transforms. As a key application, we study fragmentation functions (FFs) of charged pions and kaons from single-inclusive hadron production in electron-positron annihilation. We learn the joint distribution of momentum fraction z and energy scale Q, and infer their correlations from the entanglement structure. Building on the generalization capabilities of the quantum model and extended register architecture, we perform fine-grid multivariate sampling for FF dataset augmentation. Our results highlight the growing potential of quantum generative modeling to advance data analysis and scientific discovery in high-energy physics.
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Ardu, M., Davidson, S., & Valori, N. (2025). Left-handed physics is not right for leptonic EDMs. Eur. Phys. J. C, 85(11), 1323–12pp.
Abstract: Heavy New Physics models with lepton flavour-changing interactions are motivated by neutrino masses, and generically induce dipole interactions for leptons, which can be flavour-changing (lj→liγ) or flavour-diagonal (magnetic and electric dipole moments(edms)). We focus on models with complex couplings, and where the singlet Standard Model leptons ({eiR}) do not interact with the New Physics. In such models, edms are calculated to arise at two loops, despite that complex amplitudes for lj→liγ appear at one loop. We explore whether the extra loop suppression of edms survives flavour basis rotations that could be induced by flavour-changing NP contributions to the charged lepton mass matrix. We show that one-loop edms vanish in both the mass and Yukawa eigenstate bases.
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Olmo, G. J., Rosa, J. L., Rubiera-Garcia, D., Rueda, A., & Saez-Chillon Gomez, D. (2025). Shadows from thin accretion disks of parametrized black hole solutions. Phys. Rev. D, 112(8), 084059–19pp.
Abstract: We discuss the optical appearance from thin accretion disks in parametrized black holes, namely, solutions characterized by an arbitrarily large number of parameters without any regards to the theory of the gravitational and matter fields they come from. More precisely, we consider the leading-order terms of the spherically symmetric Johanssen-Psaltis (JP) and Konoplya-Rezzolla-Zhidenko (KRZ) parametrizations after imposing constraints from asymptotic flatness and solar system observations. Furthermore, we use the inferred correlation, by the Event Horizon Telescope Collaboration, between the size of the bright ring (which is directly observable) and the size of the central brightness depression (which is not) of M87 and Sgr A* central supermassive objects, to constrain the parameters of the leading-order JP and KRZ solutions. Using ten samples of the Standard Unbound distribution previously employed in the literature to reproduce certain scenarios of General Relativistic HydroDynamical simulations, we produce images of four samples of JP and KRZ geometries enhancing and diminishing the shadow's size, respectively. Via a qualitative and quantitative analysis of the features of the corresponding photon rings and, in particular, of their relative brightness, we argue that it should be possible to distinguish between such parametrized solutions and the Schwarzschild geometry via future upgrades of very long baseline interferometry. We furthermore consider images of some naked objects within these parametrizations, and also discuss the role of inclination in comparing images of different black holes.
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