High-energy constraints from low-energy neutrino non-standard interactions

Many scenarios of new physics predict the existence of neutrino Non-Standard Interactions, new vector contact interactions between neutrinos and first generation fermions beyond the Standard Model. We obtain model-independent constraints on the Standard Model Effective Field Theory at high energies from bounds on neutrino non-standard interactions derived at low energies. Our analysis explores a large set of new physics scenarios and includes full one-loop running effects below and above the electroweak scale. Our results show that neutrino non-standard interactions already push the scale of new physics beyond the TeV. We also conclude that bounds derived by other experimental probes, in particular by low-energy precision measurements and by charged lepton flavor violation searches, are generally more stringent. Our study constitutes a first step towards the systematization of phenomenological analyses to evaluate the impact of neutrino Non-Standard Interactions for new physics scenarios at high energies.Comment: 25 pages, 7 figures, 2 tables. Merry Christmas and happy new year

A seesaw model for large neutrino masses in concordance with cosmology

Cosmological constraints on the sum of the neutrino masses can be relaxed if the number density of active neutrinos is reduced compared to the standard scenario, while at the same time keeping the effective number of neutrino species N$_{eff}$≈3 by introducing a new component of dark radiation. We discuss a UV complete model to realise this idea, which simultaneously provides neutrino masses via the seesaw mechanism. It is based on a U(1) symmetry in the dark sector, which can be either gauged or global. In addition to heavy seesaw neutrinos, we need to introduce O(10) generations of massless sterile neutrinos providing the dark radiation. Then we can accommodate active neutrino masses with ∑m$_ν$∼1 eV, in the sensitivity range of the KATRIN experiment. We discuss the phenomenology of the model and identify the allowed parameter space. We argue that the gauged version of the model is preferred, and in this case the typical energy scale of the model is in the 10 MeV to few GeV range

A seesaw model for large neutrino masses in concordance with cosmology

Cosmological constraints on the sum of the neutrino masses can be relaxed if the number density of active neutrinos is reduced compared to the standard scenario, while at the same time keeping the effective number of neutrino species N$_{eff}$≈3 by introducing a new component of dark radiation. We discuss a UV complete model to realise this idea, which simultaneously provides neutrino masses via the seesaw mechanism. It is based on a U(1) symmetry in the dark sector, which can be either gauged or global. In addition to heavy seesaw neutrinos, we need to introduce O(10) generations of massless sterile neutrinos providing the dark radiation. Then we can accommodate active neutrino masses with ∑m$_ν$∼1 eV, in the sensitivity range of the KATRIN experiment. We discuss the phenomenology of the model and identify the allowed parameter space. We argue that the gauged version of the model is preferred, and in this case the typical energy scale of the model is in the 10 MeV to few GeV range

Supernova constraints on dark flavored sectors

Proto-neutron stars forming a few seconds after core-collapse supernovae are hot and dense environments where hyperons can be efficiently produced by weak processes. By making use of various state-of-the-art supernova simulations combined with the proper extensions of the equations of state including Λ hyperons, we calculate the cooling of the star induced by the emission of dark particles X0 through the decay Λ → nX0. Comparing this novel energy-loss process to the neutrino cooling of SN 1987A allows us to set a stringent upper limit on the branching fraction, BR(Λ → nX0 ) ≤ 8 × 10−9, that we apply to massless dark photons and axions with flavor-violating couplings to quarks. We find that the new supernova bound can be orders of magnitude stronger than other limits in dark-sector models.publishedVersio

Supernova constraints on dark flavored sectors

Proto-neutron stars forming a few seconds after core-collapse supernovae are hot and dense environments where hyperons can be efficiently produced by weak processes. By making use of various state-of-the-art supernova simulations combined with the proper extensions of the equations of state including Λ hyperons, we calculate the cooling of the star induced by the emission of dark particles X0 through the decay Λ→nX0. Comparing this novel energy-loss process to the neutrino cooling of SN 1987A allows us to set a stringent upper limit on the branching fraction, BR(Λ→nX0)≤8×10-9, that we apply to massless dark photons and axions with flavor-violating couplings to quarks. We find that the new supernova bound can be orders of magnitude stronger than other limits in dark-sector models.J. M. C. acknowledges support from the Spanish MINECO through the “Ramón y Cajal” Program No. RYC-2016-20672 and the Grant No. PGC2018-102016-A-I00. The work of J. T. C. is supported by the Ministerio de Ciencia e Innovación under FPI Contract No. PRE2019-089992 of the SEV-2015-0548 grant and Generalitat Valenciana by the SEJI/2018/033 project. The work of L. T. is supported by Contract No. FPA2016-81114-P financed by: Ministerio de Economía y Competitividad–Agencia Estatal de Investigación-FEDER, UE and Contract No. PID2019-110165GB-I00 financed by: Ministerio de Ciencia e Innovación–Agencia Estatal de Investigación-FEDER, UE, by PHAROS COST Action CA16214, and by the EU STRONG-2020 project under the program H2020-INFRAIA-2018-1, Grant agreement No. 824093. This work is partially supported by project C3b of the DFG-funded Collaborative Research Center TRR257, “Particle Physics Phenomenology after the Higgs Discovery”

New Physics Searches at Kaon and Hyperon Factories

Rare meson decays are among the most sensitive probes of both heavy and light new physics. Among them, new physics searches using kaons benefit from their small total decay widths and the availability of very large datasets. On the other hand, useful complementary information is provided by hyperon decay measurements. We summarize the relevant phenomenological models and the status of the searches in a comprehensive list of kaon and hyperon decay channels. We identify new search strategies for under-explored signatures, and demonstrate that the improved sensitivities from current and next-generation experiments could lead to a qualitative leap in the exploration of light dark sectors

New Physics Searches at Kaon and Hyperon Factories

Rare meson decays are among the most sensitive probes of both heavy and light new physics. Among them, new physics searches using kaons benefit from their small total decay widths and the availability of very large datasets. On the other hand, useful complementary information is provided by hyperon decay measurements. We summarize the relevant phenomenological models and the status of the searches in a comprehensive list of kaon and hyperon decay channels. We identify new search strategies for under-explored signatures, and demonstrate that the improved sensitivities from current and next-generation experiments could lead to a qualitative leap in the exploration of light dark sectors