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LHCb Collaboration(Aaij, R. et al), Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., & Ruiz Vidal, J. (2022). Search for the radiative Xi(-)(b) -> Xi(-)gamma decay. J. High Energy Phys., 01(1), 069–20pp.
Abstract: The first search for the rare radiative decay Xi(-)(b) -> Xi(-)gamma is performed using data collected by the LHCb experiment in proton-proton collisions at a center-of-mass energy of 13TeV, corresponding to an integrated luminosity of 5.4 fb(-1). The Xi(-)(b) -> Xi(-)-J/ psi channel is used as normalization. No Xi(-)(b) -> Xi(-)gamma signal is found and an upper limit of B(Xi(-)(b) -> Xi(-)gamma) < 1.3 x 10(-4) at 95% confidence level is obtained.
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Sierra, D. A., De Romeri, V., Flores, L. J., & Papoulias, D. K. (2022). Impact of COHERENT measurements, cross section uncertainties and new interactions on the neutrino floor. J. Cosmol. Astropart. Phys., 01(1), 055–26pp.
Abstract: We reconsider the discovery limit of multi-ton direct detection dark matter experiments in the light of recent measurements of the coherent elastic neutrino-nucleus scattering process. Assuming the cross section to be a parameter entirely determined by data, rather than using its Standard Model prediction, we use the COHERENT CsI and LAr data sets to determine WIMP discovery limits. Being based on a data-driven approach, the results are thus free from theoretical assumptions and fall within the WIMP mass regions where XENONnT and DARWIN have best expected sensitivities. We further determine the impact of subleading nuclear form factor and weak mixing angle uncertainties effects on WIMP discovery limits. We point out that these effects, albeit small, should be taken into account. Moreover, to quantify the impact of new physics effects in the neutrino background, we revisit WIMP discovery limits assuming light vector and scalar mediators as well as neutrino magnetic moments/transitions. We stress that the presence of new interactions in the neutrino sector, in general, tend to worsen the WIMP discovery limit.
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Beltran, R., Cottin, G., Helo, J. C., Hirsch, M., Titov, A., & Wang, Z. S. (2023). Long-lived heavy neutral leptons from mesons in effective field theory. J. High Energy Phys., 01(1), 015–38pp.
Abstract: In the framework of the low-energy effective field theory of the Standard Model extended with heavy neutral leptons (HNLs), we calculate the production rates of HNLs from meson decays triggered by dimension-six operators. We consider both lepton number-conserving and lepton-number-violating four-fermion operators involving either a pair of HNLs or a single HNL. Assuming that HNLs are long-lived, we perform simulations and investigate the reach of the proposed far detectors at the high-luminosity LHC to (i) active-heavy neutrino mixing and (ii) the Wilson coefficients associated with the effective operators, for HNL masses below the mass of the B-meson. We further convert the latter to the associated new-physics scales. Our results show that scales in excess of hundreds of TeV and the active-heavy mixing squared as small as 10(-15 )can be probed by these experiments.
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Fiza, N., Khan Chowdhury, N. R., & Masud, M. (2023). Investigating Lorentz Invariance Violation with the long baseline experiment P2O. J. High Energy Phys., 01(1), 076–29pp.
Abstract: One of the basic propositions of quantum field theory is Lorentz invariance. The spontaneous breaking of Lorentz symmetry at a high energy scale can be studied at low energy extensions like the Standard model in a model-independent way through effective field theory (EFT). The present and future Long-baseline neutrino experiments can give a scope to observe such a Planck-suppressed physics of Lorentz invariance violation (LIV). A proposed long baseline experiment, Protvino to ORCA (dubbed “P2O”) with a baseline of 2595 km, is expected to provide good sensitivities to unresolved issues, especially neutrino mass ordering. P2O can offer good statistics even with a moderate beam power and runtime, owing to the very large (similar to 6 Mt) detector volume at KM3NeT/ ORCA. Here we discuss in detail, how the individual LIV parameters affect neutrino oscillations at P2O and DUNE baselines at the level of probability and derive analytical expressions to understand interesting degeneracies and other features. We estimate increment Delta chi(2) sensitivities to the LIV parameters, analyzing their correlations among each other, and also with the standard oscillation parameters. We calculate these results for P2O alone and also carry out a combined analysis of P2O with DUNE. We point out crucial features in the sensitivity contours and explain them qualitatively with the help of the relevant probability expressions derived here. Finally we estimate constraints on the individual LIV parameters at 95% confidence level (C.L.) intervals stemming from the combined analysis of P2O and DUNE datasets, and highlight the improvement over the existing constraints. We also find out that the additional degeneracy induced by the LIV parameter a(ee) around -22 x 10(-23) GeV is lifted by the combined analysis at 95% C.L.
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ANTARES Collaboration(Albert, A. et al), Alves, S., Calvo, D., Carretero, V., Gozzini, R., Hernandez-Rey, J. J., et al. (2023). Limits on the nuclearite flux using the ANTARES neutrino telescope. J. Cosmol. Astropart. Phys., 01(1), 012–19pp.
Abstract: In this work, a search for nuclearites of strange quark matter by using nine years of ANTARES data taken in the period 2009-2017 is presented. The passage through matter of these particles is simulated taking into account a detailed description of the detector response to nuclearites and of the data acquisition conditions. A down-going flux of cosmic nuclearites with Galactic velocities (beta = 10(-3)) was considered for this study. The mass threshold for detecting these particles at the detector level is 4 x 10(13) GeV/c(2). Upper limits on the nuclearite flux for masses up to 10(17) GeV/c(2) at the level of similar to 5 x 10(-17) cm(-2) s(-1) sr(-1) are obtained. These are the first upper limits on nuclearites established with a neutrino telescope and the most stringent ever set for Galactic velocities.
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Boudet, S., Bombacigno, F., Moretti, F., & Olmo, G. J. (2023). Torsional birefringence in metric-affine Chern-Simons gravity: gravitational waves in late-time cosmology. J. Cosmol. Astropart. Phys., 01(1), 026–28pp.
Abstract: In the context of the metric-affine Chern-Simons gravity endowed with projective invariance, we derive analytical solutions for torsion and nonmetricity in the homogeneous and isotropic cosmological case, described by a flat Friedmann-Robertson-Walker metric. We discuss in some details the general properties of the cosmological solutions in the presence of a perfect fluid, such as the dynamical stability and the emergence of big bounce points, and we examine the structure of some specific solutions reproducing de Sitter and power law behaviours for the scale factor. Then, we focus on first-order perturbations in the de Sitter scenario, and we study the propagation of gravitational waves in the adiabatic limit, looking at tensor and scalar polarizations. In particular, we find that metric tensor modes couple to torsion tensor components, leading to the appearance, as in the metric version of Chern-Simons gravity, of birefringence, characterized by different dispersion relations for the left and right circularized polarization states. As a result, the purely tensor part of torsion propagates like a wave, while nonmetricity decouples and behaves like a harmonic oscillator. Finally, we discuss scalar modes, outlining as they decay exponentially in time and do not propagate.
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Carrasco, J., & Zurita, J. (2024). Emerging jet probes of strongly interacting dark sectors. J. High Energy Phys., 01(1), 034–23pp.
Abstract: A strongly interacting dark sector can give rise to a class of signatures dubbed dark showers, where in analogy to the strong sector in the Standard Model, the dark sector undergoes its own showering and hadronization, before decaying into Standard Model final states. When the typical decay lengths of the dark sector mesons are larger than a few centimeters (and no larger than a few meters) they give rise to the striking signature of emerging jets, characterized by a large multiplicity of displaced vertices.In this article we consider the general reinterpretation of the CMS search for emerging jets plus prompt jets into arbitrary new physics scenarios giving rise to emerging jets. More concretely, we consider the cases where the SM Higgs mediates between the dark sector and the SM, for several benchmark decay scenarios. Our procedure is validated employing the same model than the CMS emerging jet search. We find that emerging jets can be the leading probe in regions of parameter space, in particular when considering the so-called gluon portal and dark photon portal decay benchmarks. With the current 16.1 fb-1 of luminosity this search can exclude down to O\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \mathcal{O} $$\end{document}(20)% exotic branching ratio of the SM Higgs, but a naive extrapolation to the 139 fb-1 luminosity employed in the current model-independent, indirect bound of 16 % would probe exotic branching ratios into dark quarks down to below 10 %. Further extrapolating these results to the HL-LHC, we find that one can pin down exotic branching ratio values of 1%, which is below the HL-LHC expectations of 2.5-4 %. We make our recasting code publicly available, as part of the LLP Recasting Repository.
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Herrero-Brocal, A., & Vicente, A. (2024). The majoron coupling to charged leptons. J. High Energy Phys., 01(1), 078–33pp.
Abstract: The particle spectrum of all Majorana neutrino mass models with spontaneous violation of global lepton number include a Goldstone boson, the so-called majoron. The presence of this massless pseudoscalar changes the phenomenology dramatically. In this work we derive general analytical expressions for the 1-loop coupling of the majoron to charged leptons. These can be applied to any model featuring a majoron that have a clear hierarchy of energy scales, required for an expansion in powers of the low-energy scale to be valid. We show how to use our general results by applying them to some example models, finding full agreement with previous results in several popular scenarios and deriving novel ones in other setups.
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Penalva, N., Flynn, J. M., Hernandez, E., & Nieves, J. (2024). Study of new physics effects in (B)over-bars → Ds(*) τ-(ν)over-bar τ semileptonic decays using lattice QCD form factors and heavy quark effective theory. J. High Energy Phys., 01(1), 163–33pp.
Abstract: We benefit from the lattice QCD determination by the HPQCD of the Standard Model (SM) form factors for the (B) over bar (s) -> D-s [Phys. Rev. D101(2020) 074513] and the SM and tensor ones for the (B) over bar (s) -> D-s* (arXiv:2304.03137[hep-lat]) semileptonic decays, and the heavy quark effective theory (HQET) relations for the analogous B -> D-(*()) decays obtained by F.U. Bernlochner et al. in Phys. Rev. D95(2017) 115008, to extract the leading and sub-leading Isgur-Wise functions for the (B) over bar (s) -> D-s(()*()) decays. Further use of the HQET relations allows us to evaluate the corresponding scalar, pseudoscalar and tensor form factors needed for a phenomenological study of new physics (NP) effects on the (B) over bar (s) -> D-s(()*()) semileptonic decay. At present, the experimental values for the ratios R-D(*) = Gamma[ (B) over bar -> D-(*())(tau- (nu) over bar tau)]/Gamma[(B) over bar -> D-(*())e(-)(mu(-)) (nu) over bar (e(mu))]are the best signal in favor of lepton flavor universality violation (LFUV) seen in charged current (CC) b -> c decays. In this work we conduct a study of NP effects on the (B) over bar (s) -> D-s(()*()) tau(-)(tau) semileptonic decays by comparing tau spin, angular and spin-angular asymmetry distributions obtained within the SM and three different NP scenarios. As expected from SU(3) light-flavor symmetry, we get results close to the ones found in a similar analysis of the (B) over bar -> D-(*()) case. The measurement of the (B) over bar (s) -> D-s(()*())(l (nu) over bar tau) semileptonic decays, which is within reach of present experiments, could then be of relevance in helping to establish or rule out LFUV in CC b -> c transitions.
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Coloma, P., López-Pavón, J., Molina-Bueno, L., & Urrea, S. (2024). New physics searches using ProtoDUNE and the CERN SPS accelerator. J. High Energy Phys., 01(1), 134–18pp.
Abstract: The exquisite capabilities of liquid Argon Time Projection Chambers make them ideal to search for weakly interacting particles in Beyond the Standard Model scenarios. Given their location at CERN the ProtoDUNE detectors may be exposed to a flux of such particles, produced in the collisions of 400 GeV protons (extracted from the Super Proton Synchrotron accelerator) on a target. Here we point out the interesting possibilities that such a setup offers to search for both long-lived unstable particles (Heavy Neutral Leptons, axion-like particles, etc) and stable particles (e.g. light dark matter, or millicharged particles). Our results show that, under conservative assumptions regarding the expected luminosity, this setup has the potential to improve over present bounds for some of the scenarios considered. This could be done within a short timescale, using facilities that are already in place at CERN, and without interfering with the experimental program in the North Area at CERN.
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