Fernandez Navarro, M., King, S. F., & Vicente, A. (2024). Tri-unification: a separate SU(5) for each fermion family. J. High Energy Phys., 05(5), 130–32pp.
Abstract: In this paper we discuss SU(5)3 with cyclic symmetry as a possible grand unified theory (GUT). The basic idea of such a tri-unification is that there is a separate SU(5) for each fermion family, with the light Higgs doublet(s) arising from the third family SU(5), providing a basis for charged fermion mass hierarchies. SU(5)3 tri-unification reconciles the idea of gauge non-universality with the idea of gauge coupling unification, opening the possibility to build consistent non-universal descriptions of Nature that are valid all the way up to the scale of grand unification. As a concrete example, we propose a grand unified embedding of the tri-hypercharge model \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\text{U}}{\left(1\right)}_{Y}<^>{3}$$\end{document} based on an SU(5)3 framework with cyclic symmetry. We discuss a minimal tri-hypercharge example which can account for all the quark and lepton (including neutrino) masses and mixing parameters. We show that it is possible to unify the many gauge couplings into a single gauge coupling associated with the cyclic SU(5)3 gauge group, by assuming minimal multiplet splitting, together with a set of relatively light colour octet scalars. We also study proton decay in this example, and present the predictions for the proton lifetime in the dominant e+pi 0 channel.
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Chu, X. Y., Garani, R., Garcia-Cely, C., & Hambye, T. (2024). Dark matter bound-state formation in the Sun. J. High Energy Phys., 05(5), 045–32pp.
Abstract: The Sun may capture asymmetric dark matter (DM), which can subsequently form bound-states through the radiative emission of a sub-GeV scalar. This process enables generation of scalars without requiring DM annihilation. In addition to DM capture on nucleons, the DM-scalar coupling responsible for bound-state formation also induces capture from self-scatterings of ambient DM particles with DM particles already captured, as well as with DM bound-states formed in-situ within the Sun. This scenario is studied in detail by solving Boltzmann equations numerically and analytically. In particular, we take into consideration that the DM self-capture rates require a treatment beyond the conventional Born approximation. We show that, thanks to DM scatterings on bound-states, the number of DM particles captured increases exponentially, leading to enhanced emission of relativistic scalars through bound-state formation, whose final decay products could be observable. We explore phenomenological signatures with the example that the scalar mediator decays to neutrinos. We find that the neutrino flux emitted can be comparable to atmospheric neutrino fluxes within the range of energies below one hundred MeV. Future facilities like Hyper-K, and direct DM detection experiments can further test such scenario.
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Giarnetti, A., Herrero-Garcia, J., Marciano, S., Meloni, D., & Vatsyayan, D. (2024). Neutrino masses from new Weinberg-like operators: phenomenology of TeV scalar multiplets. J. High Energy Phys., 05(5), 055–37pp.
Abstract: The unique dimension-5 effective operator, LLHH, known as the Weinberg operator, generates tiny Majorana masses for neutrinos after electroweak spontaneous symmetry breaking. If there are new scalar multiplets that take vacuum expectation values (VEVs), they should not be far from the electroweak scale. Consequently, they may generate new dimension-5 Weinberg-like operators which in turn also contribute to Majorana neutrino masses. In this study, we consider scenarios with one or two new scalars up to quintuplet SU(2) representations. We analyse the scalar potentials, studying whether the new VEVs can be induced and therefore are naturally suppressed, as well as the potential existence of pseudo-Nambu-Goldstone bosons. Additionally, we also obtain general limits on the new scalar multiplets from direct searches at colliders, loop corrections to electroweak precision tests and the W-boson mass.
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Forconi, M., Giare, W., Mena, O., Ruchika, Di Valentino, E., Melchiorri, A., et al. (2024). A double take on early and interacting dark energy from JWST. J. Cosmol. Astropart. Phys., 05(5), 097–37pp.
Abstract: The very first light captured by the James Webb Space Telescope (JWST) revealed a population of galaxies at very high redshifts more massive than expected in the canonical Lambda CDM model of structure formation. Barring, among others, a systematic origin of the issue, in this paper, we test alternative cosmological perturbation histories. We argue that models with a larger matter component ohm m and/or a larger scalar spectral index n s can substantially improve the fit to JWST measurements. In this regard, phenomenological extensions related to the dark energy sector of the theory are appealing alternatives, with Early Dark Energy emerging as an excellent candidate to explain (at least in part) the unexpected JWST preference for larger stellar mass densities. Conversely, Interacting Dark Energy models, despite producing higher values of matter clustering parameters such as sigma 8 , are generally disfavored by JWST measurements. This is due to the energy -momentum flow from the dark matter to the dark energy sector, implying a smaller matter energy density. Upcoming observations may either strengthen the evidence or falsify some of these appealing phenomenological alternatives to the simplest Lambda CDM picture.
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Gorkavenko, V., Jashal, B. K., Kholoimov, V., Kyselov, Y., Mendoza, D., Ovchynnikov, M., et al. (2024). LHCb potential to discover long-lived new physics particles with lifetimes above 100 ps. Eur. Phys. J. C, 84(6), 608–15pp.
Abstract: For years, it has been believed that the main LHC detectors can play only a limited role of a lifetime frontier experiment exploring the parameter space of long-lived particles (LLPs)-hypothetical particles with tiny couplings to the Standard Model. This paper demonstrates that the LHCb experiment may become a powerful lifetime frontier experiment if it uses the new Downstream algorithm reconstructing tracks that do not allow hits in the LHCb vertex tracker. In particular, for many LLP scenarios, LHCb may be as sensitive as the proposed experiments beyond the main LHC detectors for various LLP models, including heavy neutral leptons, dark scalars, dark photons, and axion-like particles.
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Baeza-Ballesteros, J., Donini, A., Molina-Terriza, G., Monrabal, F., & Simon, A. (2024). Towards a realistic setup for a dynamical measurement of deviations from Newton's 1/r2 law: the impact of air viscosity. Eur. Phys. J. C, 84(6), 596–20pp.
Abstract: A novel experimental setup to measure deviations from the 1/r(2) distance dependence of Newtonian gravity was proposed in Donini and Marimon (Eur Phys J C 76:696, 2016). The underlying theoretical idea was to study the orbits of a microscopically-sized planetary system composed of a “Satellite”, with mass m(S) similar to O(10-9) g, and a “Planet”, with mass M-P similar to O(10-5) g at an initial distance of hundreds of microns. The detection of precession of the orbit in this system would be an unambiguous indication of a central potential with terms that scale with the distance differently from 1/r. This is a huge advantage with respect to the measurement of the absolute strength of the attraction between two bodies, as most electrically-induced background potentials do indeed scale as 1/r. Detection of orbit precession is unaffected by these effects, allowing for better sensitivities. In Baeza-Ballesteros et al. (Eur Phys J C 82:154, 2022), the impact of other subleading backgrounds that may induce orbit precession, such as, e.g., the electrical Casimir force or general relativity, was studied in detail. It was found that the proposed setup could test Yukawa-like corrections, alpha x exp(-r/lambda), to the 1/r potential with couplings as low as alpha similar to 10(-2) for distances as small as lambda similar to 10 μm, improving by roughly an order of magnitude present bounds. In this paper, we start to move from a theoretical study of the proposal to a more realistic implementation of the experimental setup. As a first step, we study the impact of air viscosity on the proposed setup and see how the setup should be modified in order to preserve the theoretical sensitivity achieved in Donini and Marimon (2016) and Baeza-Ballesteros et al. (2022).
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Bhattacharya, S., Mondal, N., Roshan, R., & Vatsyayan, D. (2024). Leptogenesis, dark matter and gravitational waves from discrete symmetry breaking. J. Cosmol. Astropart. Phys., 06(6), 029–25pp.
Abstract: We analyse a model that connects the neutrino sector and the dark sector of the universe via a mediator 41., stabilised by a discrete Z4 symmetry that breaks to a remnant Z2 upon 41. acquiring a non -zero vacuum expectation value (v phi). The model accounts for the observed baryon asymmetry of the universe via additional contributions to the canonical Type -I leptogenesis. The Z4 symmetry breaking scale (v phi) in the model not only establishes a connection between the neutrino sector and the dark sector, but could also lead to gravitational wave signals that are within the reach of current and future experimental sensitivities.
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Gargalionis, J., Herrero-Garcia, J., & Schmidt, M. A. (2024). Model-independent estimates for loop-induced baryon-number-violating nucleon decays. J. High Energy Phys., 06(6), 182–52pp.
Abstract: Baryon number is an accidental symmetry of the Standard Model (SM) Lagrangian that so far has been measured to be exactly preserved, although it is expected to be violated at higher energies. In this work we compute order-of-magnitude estimates for the matching contributions of generic ultraviolet models to effective operators that generate nucleon decay processes. This is done in a systematic and automated way using operators constructed from SM fields up to dimension nine and working in a framework that has proved useful in the study of lepton-number violation. For each of the operators we derive estimates for the rates of different nucleon-decay channels. These allow us to establish model-independent lower bounds on the underlying new-physics scale and identify potential correlations between the various decay modes. The results are most relevant for families of models that generate the considered operator. This analysis is especially timely given the expected future sensitivities in numerous experiments such as Hyper-K, DUNE, JUNO and THEIA.
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Maluf, R. V., Mora-Perez, G., Olmo, G. J., & Rubiera-Garcia, D. (2024). Nonsingular, Lump-like, Scalar Compact Objects in (2+1)-Dimensional Einstein Gravity. Universe, 10(6), 258–13pp.
Abstract: We study the space-time geometry generated by coupling a free scalar field with a noncanonical kinetic term to general relativity in (2+1) dimensions. After identifying a family of scalar Lagrangians that yield exact analytical solutions in static and circularly symmetric scenarios, we classify the various types of solutions and focus on a branch that yields asymptotically flat geometries. We show that the solutions within such a branch can be divided in two types, namely naked singularities and nonsingular objects without a center. In the latter, the energy density is localized around a maximum and vanishes only at infinity and at an inner boundary. This boundary has vanishing curvatures and cannot be reached by any time-like or null geodesic in finite affine time. This allows us to consistently interpret such solutions as nonsingular, lump-like, static compact scalar objects whose eventual extension to the (3+1)-dimensional context could provide structures of astrophysical interest.
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IDS Collaboration(Andel, B. et al), Algora, A., & Nacher, E. (2024). β decay of the ground state and of a low-lying isomer in Bi-216. Phys. Rev. C, 109(6), 064321–18pp.
Abstract: A detailed beta -decay study of the low- and high -spin states in 216 Bi has been performed at the ISOLDE Decay Station at the CERN-ISOLDE facility. In total, 48 new levels and 83 new transitions in the beta -decay daughter 216 Po were identified. Shell -model calculations for excited states in 216 Bi and 216 Po were performed using the H208 and the modified Kuo-Herling particle effective interactions. Based on the experimental observations and the shell -model calculations, the most likely spin and parity assignments for the beta -decaying states in 216 Bi are (3 – ) and (8 – ), respectively.
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