Abstract: We present a detailed analysis of the spectral data of Borexino Phase II, with the aim of exploiting its full potential to constrain scenarios beyond the Standard Model. In particular, we quantify the constraints imposed on neutrino magnetic moments, neutrino non-standard interactions, and several simplified models with light scalar, pseudoscalar or vector mediators. Our analysis shows perfect agreement with those performed by the collaboration on neutrino magnetic moments and neutrino non-standard interactions in the same restricted cases and expands beyond those, stressing the interplay between flavour oscillations and flavour non-diagonal interaction effects for the correct evaluation of the event rates. For simplified models with light mediators we show the power of the spectral data to obtain robust limits beyond those previously estimated in the literature.

Abstract: Motivated by the XENON1T excess in electron-recoil measurements, we investigate the prospects of probing axion-like particles (ALP) in lepton flavor violation experiments. In particular, we identify such ALP as a pseudo-Goldstone from the spontaneous breaking of the flavor symmetries that explain the mixing structure of the Standard Model leptons. We present the case of the flavor symmetries being a non-Abelian U(2) and the ALP originating from its U(1) subgroup, which is anomaly-free with the Standard Model group. We build two explicit realistic examples that reproduce leptonic masses and mixings and show that the ALP which is consistent with XENON1T anomaly could be probed by the proposed LFV experiments.

Abstract: Primordial black holes (PBHs) formed in the early Universe are sources of neutrinos emitted via Hawking radiation. Such astrophysical neutrinos could be detected at Earth and constraints on the abundance of comet-mass PBHs could be derived from the null observation of this neutrino flux. Here, we consider non-rotating PBHs and improve constraints using Super-Kamiokande neutrino data, as well as we perform forecasts for next-generation neutrino (Hyper-Kamiokande, JUNO, DUNE) and dark matter (DARWIN, ARGO) detectors, which we compare. For PBHs less massive than " few x 1014 g, PBHs would have already evaporated by now, whereas more massive PBHs would still be present and would constitute a fraction of the dark matter of the Universe. We consider monochromatic and extended (log-normal) mass distributions, and a PBH mass range spanning from 1012 g to ti 1016 g. Finally, we also compare our results with previous ones in the literature.

Abstract: We study the (B) over bar (0)(s) -> J/psi f(0)(980) and (B) over bar (0)(s) -> J/psi a(0)(980) reactions, and pay attention to the different sources of isospin violation and mixing of f(0)(980) and a(0)(980) resonances where these resonances are dynamically generated from meson-meson interactions. We fmd that the main cause of isospin violation is isospin breaking in the meson-meson transition T matrices, and the other source is that the loops involving kaons in the production mechanism do not cancel due to the different masses of charged and neutral kaons. We obtain a branching ratio for a(0)(980) production of the order of 5 x 10(-6) . Future experiments can address this problem, and the production rate and shape of the pi(0)eta mass distribution will definitely help to better understand the nature of scalar resonances.

Abstract: We consider a type-I seesaw framework endowed with a flavour symmetry, belonging to the series of non-abelian groups increment (3 n(2)) and increment (6 n(2)), and a CP symmetry. Breaking these symmetries in a non-trivial way results in the right-handed neutrinos being degenerate in mass up to possible (further symmetry-breaking) splittings kappa and lambda, while the neutrino Yukawa coupling matrix encodes the entire flavour structure in the neutrino sector. For a fixed combination of flavour and CP symmetry and residual groups, this matrix contains five real free parameters. Four of them are determined by the light neutrino mass spectrum and by accommodating experimental data on lepton mixing well, while the angle theta(R) is related to right-handed neutrinos. We scrutinise for all four lepton mixing patterns, grouped into Case 1) through Case 3 b.1), the potential to generate the baryon asymmetry of the Universe through low-scale leptogenesis numerically and analytically. The main results are: a) the possible correlation of the baryon asymmetry and the Majorana phases, encoded in the Pontecorvo-Maki-Nakagawa-Sakata mixing matrix, in certain instances; b) the possibility to generate the correct amount of baryon asymmetry for vanishing splittings kappa and lambda among the right-handed neutrinos as well as for large kappa, depending on the case and the specific choice of group theory parameters; c) the chance to produce sufficient baryon asymmetry for large active-sterile mixing angles, enabling direct experimental tests at current and future facilities, if theta(R) is close to a special value, potentially protected by an enhanced residual symmetry. We elucidate these results with representative examples of flavour and CP symmetries, which all lead to a good agreement with the measured values of the lepton mixing angles and, possibly, the current indication of the CP phase delta. We identify the CP-violating combinations relevant for low-scale leptogenesis, and show that the parametric dependence of the baryon asymmetry found in the numerical study can be understood well with their help.