Mandal, S., Romao, J. C., Srivastava, R., & Valle, J. W. F. (2021). Dynamical inverse seesaw mechanism as a simple benchmark for electroweak breaking and Higgs boson studies. J. High Energy Phys., 07(7), 029–38pp.
Abstract: The Standard Model (SM) vacuum is unstable for the measured values of the top Yukawa coupling and Higgs mass. Here we study the issue of vacuum stability when neutrino masses are generated through spontaneous low-scale lepton number violation. In the simplest dynamical inverse seesaw, the SM Higgs has two siblings: a massive CP-even scalar plus a massless Nambu-Goldstone boson, called majoron. For TeV scale breaking of lepton number, Higgs bosons can have a sizeable decay into the invisible majorons. We examine the interplay and complementarity of vacuum stability and perturbativity restrictions, with collider constraints on visible and invisible Higgs boson decay channels. This simple framework may help guiding further studies, for example, at the proposed FCC facility.
|
Escrihuela, F. J., Flores, L. J., Miranda, O. G., & Rendon, J. (2021). Global constraints on neutral-current generalized neutrino interactions. J. High Energy Phys., 07(7), 061–26pp.
Abstract: We study generalized neutrino interactions (GNI) for several neutrino processes, including neutrinos from electron-positron collisions, neutrino-electron scattering, and neutrino deep inelastic scattering. We constrain scalar, pseudoscalar, and tensor new physics effective couplings, based on the standard model effective field theory at low energies. We have performed a global analysis for the different effective couplings. We also present the different individual constraints for each effective parameter (scalar, pseudoscalar, and tensor). Being a global analysis, we show robust results for the restrictions on the different GNI parameters and improve some of these bounds.
|
Beniwal, A., Herrero-Garcia, J., Leerdam, N., White, M., & Williams, A. G. (2021). The ScotoSinglet Model: a scalar singlet extension of the Scotogenic Model. J. High Energy Phys., 06(6), 136–34pp.
Abstract: The Scotogenic Model is one of the most minimal models to account for both neutrino masses and dark matter (DM). In this model, neutrino masses are generated at the one-loop level, and in principle, both the lightest fermion singlet and the lightest neutral component of the scalar doublet can be viable DM candidates. However, the correct DM relic abundance can only be obtained in somewhat small regions of the parameter space, as there are strong constraints stemming from lepton flavour violation, neutrino masses, electroweak precision tests and direct detection. For the case of scalar DM, a sufficiently large lepton-number-violating coupling is required, whereas for fermionic DM, coannihilations are typically necessary. In this work, we study how the new scalar singlet modifies the phenomenology of the Scotogenic Model, particularly in the case of scalar DM. We find that the new singlet modifies both the phenomenology of neutrino masses and scalar DM, and opens up a large portion of the parameter space of the original model.
|
Masud, M., Mehta, P., Ternes, C. A., & Tortola, M. (2021). Non-standard neutrino oscillations: perspective from unitarity triangles. J. High Energy Phys., 05(5), 171–19pp.
Abstract: We formulate an alternative approach based on unitarity triangles to describe neutrino oscillations in presence of non-standard interactions (NSI). Using perturbation theory, we derive the expression for the oscillation probability in case of NSI and cast it in terms of the three independent parameters of the leptonic unitarity triangle (LUT). The form invariance of the probability expression (even in presence of new physics scenario as long as the mixing matrix is unitary) facilitates a neat geometric view of neutrino oscillations in terms of LUT. We examine the regime of validity of perturbative expansions in the NSI case and make comparisons with approximate expressions existing in literature. We uncover some interesting dependencies on NSI terms while studying the evolution of LUT parameters and the Jarlskog invariant. Interestingly, the geometric approach based on LUT allows us to express the oscillation probabilities for a given pair of neutrino flavours in terms of only three (and not four) degrees of freedom which are related to the geometric properties (sides and angles) of the triangle. Moreover, the LUT parameters are invariant under rephasing transformations and independent of the parameterization adopted.
|
Felkl, T., Herrero-Garcia, J., & Schmidt, M. A. (2021). The singly-charged scalar singlet as the origin of neutrino masses. J. High Energy Phys., 05(5), 122–39pp.
Abstract: We consider the generation of neutrino masses via a singly-charged scalar singlet. Under general assumptions we identify two distinct structures for the neutrino mass matrix. This yields a constraint for the antisymmetric Yukawa coupling of the singly-charged scalar singlet to two left-handed lepton doublets, irrespective of how the breaking of lepton-number conservation is achieved. The constraint disfavours large hierarchies among the Yukawa couplings. We study the implications for the phenomenology of lepton-flavour universality, measurements of the W-boson mass, flavour violation in the charged-lepton sector and decays of the singly-charged scalar singlet. We also discuss the parameter space that can address the Cabibbo Angle Anomaly.
|
Bennett, J. J., Buldgen, G., de Salas, P. F., Drewes, M., Gariazzo, S., Pastor, S., et al. (2021). Towards a precision calculation of the effective number of neutrinos N-eff in the Standard Model. Part II. Neutrino decoupling in the presence of flavour oscillations and finite-temperature QED. J. Cosmol. Astropart. Phys., 04(4), 073–33pp.
Abstract: We present in this work a new calculation of the standard-model benchmark value for the effective number of neutrinos, N-eff(SM), that quantifies the cosmological neutrinoto-photon energy densities. The calculation takes into account neutrino flavour oscillations, finite-temperature effects in the quantum electrodynamics plasma to O(e(3)), where e is the elementary electric charge, and a full evaluation of the neutrino-neutrino collision integral. We provide furthermore a detailed assessment of the uncertainties in the benchmark N(eff)(SM )value, through testing the value's dependence on (i) optional approximate modelling of the weak collision integrals, (ii) measurement errors in the physical parameters of the weak sector, and (iii) numerical convergence, particularly in relation to momentum discretisation. Our new, recommended standard-model benchmark is N-eff(SM) 3.0440 +/- 0.0002, where the nominal uncertainty is attributed predominantly to errors incurred in the numerical solution procedure (vertical bar delta N-eff vertical bar similar to 10(-4)), augmented by measurement errors in the solar mixing angle sin(2) theta(12) (vertical bar delta N-eff vertical bar similar to 10(-4)).
|
ANTARES Collaboration(Albert, A. et al), Alves, S., Carretero, V., Colomer, M., Gozzini, R., Hernandez-Rey, J. J., et al. (2021). Measurement of the atmospheric nu(e) and nu(mu) energy spectra with the ANTARES neutrino telescope. Phys. Lett. B, 816, 136228–7pp.
Abstract: This letter presents a combined measurement of the energy spectra of atmospheric nu(e) and nu(mu) in the energy range between similar to 100 GeV and similar to 50 TeV with the ANTARES neutrino telescope. The analysis uses 3012 days of detector livetime in the period 2007-2017, and selects 1016 neutrinos interacting in (or close to) the instrumented volume of the detector, yielding shower-like events (mainly from nu(e) + (nu) over bar (e) charged current plus all neutrino neutral current interactions) and starting track events (mainly from nu(mu) + (nu) over bar (mu) charged current interactions). The contamination by atmospheric muons in the final sample is suppressed at the level of a few per mill by different steps in the selection analysis, including a Boosted Decision Tree classifier. The distribution of reconstructed events is unfolded in terms of electron and muon neutrino fluxes. The derived energy spectra are compared with previous measurements that, above 100 GeV, are limited to experiments in polar ice and, for nu(mu), to Super-Kamiokande.
|
Barreiros, D. M., Joaquim, F. R., Srivastava, R., & Valle, J. W. F. (2021). Minimal scoto-seesaw mechanism with spontaneous CP violation. J. High Energy Phys., 04(4), 249–21pp.
Abstract: We propose simple scoto-seesaw models to account for dark matter and neutrino masses with spontaneous CP violation. This is achieved with a single horizontal Z8 discrete symmetry, broken to a residual Z2 subgroup responsible for stabilizing dark matter. CP is broken spontaneously via the complex vacuum expectation value of a scalar singlet, inducing leptonic CP-violating effects. We find that the imposed Z8 symmetry pushes the values of the Dirac CP phase and the lightest neutrino mass to ranges already probed by ongoing experiments, so that normal-ordered neutrino masses can be cornered by cosmological observations and neutrinoless double beta decay experiments.
|
Dev, A., Machado, P. A. N., & Martinez-Mirave, P. (2021). Signatures of ultralight dark matter in neutrino oscillation experiments. J. High Energy Phys., 01(1), 094–23pp.
Abstract: We study how neutrino oscillations could probe the existence of ultralight bosonic dark matter. Three distinct signatures on neutrino oscillations are identified, depending on the mass of the dark matter and the specific experimental setup. These are time modulation signals, oscillation probability distortions due to fast modulations, and fast varying matter effects. We provide all the necessary information to perform a bottom-up, model-independent experimental analysis to probe such scenarios. Using the future DUNE experiment as an example, we estimate its sensitivity to ultralight scalar dark matter. Our results could be easily used by any other oscillation experiment.
|
Sierra, D. A., De Romeri, V., Flores, L. J., & Papoulias, D. K. (2021). Axionlike particles searches in reactor experiments. J. High Energy Phys., 03(3), 294–38pp.
Abstract: Reactor neutrino experiments provide a rich environment for the study of axionlike particles (ALPs). Using the intense photon flux produced in the nuclear reactor core, these experiments have the potential to probe ALPs with masses below 10MeV. We explore the feasibility of these searches by considering ALPs produced through Primakoff and Compton-like processes as well as nuclear transitions. These particles can subsequently interact with the material of a nearby detector via inverse Primakoff and inverse Compton-like scatterings, via axio-electric absorption, or they can decay into photon or electron-positron pairs. We demonstrate that reactor-based neutrino experiments have a high potential to test ALP-photon couplings and masses, currently probed only by cosmological and astrophysical observations, thus providing complementary laboratory-based searches. We furthermore show how reactor facilities will be able to test previously unexplored regions in the similar to MeV ALP mass range and ALP-electron couplings of the order of gaee similar to 10(-8) as well as ALP-nucleon couplings of the order of g (1) ann similar to 10(-9), testing regions beyond TEXONO and Borexino limits.
|
