We consider the effects of active-sterile secret neutrino interactions, mediated by a new pseudoscalar particle, on high and ultrahigh energy neutrino fluxes. In particular, we focus on the case of ...three active and one sterile neutrino coupled by a flavor dependent interaction, extending the case of one active and one sterile neutrino we have recently examined. We find that, depending on the kind of interaction of a sterile neutrino with the active sector, new regions of the parameter space for secret interactions are now allowed, with the masses of a sterile neutrino and scalar mediator ranging from 10 MeV to 1 GeV, leading to interesting phenomenological implications on two benchmark fluxes we consider, namely an astrophysical power law flux, in the range below 100 PeV, and a cosmogenic flux, in the ultrahigh energy range. First of all, the final active fluxes can present a measurable depletion observable in future experiments. Especially, in the case of only a ντ − νs interaction, we find that the effects on the astrophysical power law flux can be so large to be already probed by the IceCube experiment. Moreover, we find intriguing features in the energy dependence of the flavor ratio.
Light sterile neutrinos mixing with the active ones have been recently proposed to solve different anomalies observed in short-baseline oscillation experiments. These neutrinos can also be produced ...by oscillations of the active neutrinos in the early universe, leaving possible traces on different cosmological observables. Here we perform an updated study of the neutrino kinetic equations in (3+1) and (2+1) oscillation schemes, dynamically evolving primordial asymmetries of active neutrinos and taking into account for the first time CP-violation effects. In the absence of neutrino asymmetries, eV-mass scale sterile neutrinos would be completely thermalized creating a tension with respect to the CMB, LSS and BBN data. In the past literature, active neutrino asymmetries have been invoked as a way to inhibit the sterile neutrino production via the in-medium suppression of the sterile-active mixing angle. However, neutrino asymmetries also permit a resonant sterile neutrino production. We find that if the active species have equal asymmetries L, a value |L|=10^{-3} is required to start suppressing the resonant sterile production, roughly an order of magnitude larger than what previously expected. When active species have opposite asymmetries the sterile abundance is further enhanced, requiring an even larger |L|\simeq 10^{-2} to start suppressing their production. In the latter case, CP-violation (naturally expected) further exacerbates the phenomenon. Some consequences for cosmological observables are briefly discussed: for example, it is likely that moderate suppressions of the sterile species production are associated with significant spectral distortions of the active neutrino species, with potentially interesting phenomenological consequences especially for BBN.
The tendency of individual CpG sites to be methylated is distinctive, non-random and well-regulated throughout the genome. We investigated the structural and spatial factors influencing CpGs ...methylation by performing an ultra-deep targeted methylation analysis on human, mouse and zebrafish genes. We found that methylation is not a random process and that closer neighboring CpG sites are more likely to share the same methylation status. Moreover, if the distance between CpGs increases, the degree of co-methylation decreases. We set up a simulation model to analyze the contribution of both the intrinsic susceptibility and the distance effect on the probability of a CpG to be methylated. Our finding suggests that the establishment of a specific methylation pattern follows a universal rule that must take into account of the synergistic and dynamic interplay of these two main factors: the intrinsic methylation susceptibility of specific CpG and the nucleotide distance between two CpG sites.
•The methylation of CpGs occurs in a non-stochastic manner.•Some CpG sites are more prone to be methylated than others.•Closer CpG sites are more likely to be co-methylated.•The degree of co-methylation decreases as the distance between CpG sites increases.
We investigate the effects on sub-TeV resonant leptogenesis of primordial black holes with masses from 10 6 g to ∼ 10 9 g . The latter might dominate the energy content of the Universe altering its ...evolution and, eventually, diluting the final baryon asymmetry. We find that, depending on the mass and abundance of primordial black holes, the parameter space of sub-TeV resonant leptogenesis shrinks towards higher right-handed neutrino masses and smaller active-sterile mixing. Remarkably, this translates into important implications for the experimental searches of heavy neutral leptons. Conversely, we demonstrate that a possible future detection of sub-TeV heavy neutral leptons would disfavor regions of the parameter space of primordial black holes currently allowed. Published by the American Physical Society 2024
ABSTRACT
Starburst galaxies, which are known as ‘reservoirs’ of high-energy cosmic-rays, can represent an important high-energy neutrino ‘factory’ contributing to the diffuse neutrino flux observed ...by IceCube. In this paper, we revisit the constraints affecting the neutrino and gamma-ray hadronuclear emissions from this class of astrophysical objects. In particular, we go beyond the standard prototype-based approach leading to a simple power-law neutrino flux, and investigate a more realistic model based on a data-driven blending of spectral indexes, thereby capturing the observed changes in the properties of individual emitters. We then perform a multi-messenger analysis considering the extragalactic gamma-ray background (EGB) measured by Fermi-LAT and different IceCube data samples: the 7.5-yr high-energy starting events (HESE) and the 6-yr high-energy cascade data. Along with starburst galaxies, we take into account the contributions from blazars and radio galaxies as well as the secondary gamma-rays from electromagnetic cascades. Remarkably, we find that, differently from the highly-constrained prototype scenario, the spectral index blending allows starburst galaxies to account for up to $40{{\ \rm per\ cent}}$ of the HESE events at $95.4{{\ \rm per\ cent}}$ CL, while satisfying the limit on the non-blazar EGB component. Moreover, values of $\mathcal {O}(100\, \mathrm{PeV})$ for the maximal energy of accelerated cosmic-rays by supernovae remnants inside the starburst are disfavoured in our scenario. In broad terms, our analysis points out that a better modelling of astrophysical sources could alleviate the tension between neutrino and gamma-ray data interpretation.
ABSTRACT
The gamma-ray emission from Starburst and Star-forming Galaxies (SBGs and SFGs) strongly suggests a correlation between star-forming activity and gamma-ray luminosity. However, the very ...nature of cosmic ray (CR) transport and the degree of their confinement within SBG cores are still open questions
. We aim at probing the imprints left by CR transport on gamma-ray and neutrino observations of point-like SFGs and SBGs, looking into quantitative ways to discriminate among different transport models. We analyse the 10-yr Fermi-LAT spectral energy distributions of 13 nearby galaxies with two different CR transport models, taking into account the corresponding IR and UV observations. We also generate mock gamma-ray data to simulate the CTA performance in detecting these sources. In this way, we propose a test to discriminate between the two CR models, quantifying the statistical confidence at which one model can be preferred over the other. We point out that the current data already give a slight preference to CR models that are dominated by advection. Moreover, we show that CTA will allow us to firmly disfavour models dominated by diffusion over self-induced turbulence, compared to advection-dominated models, with Bayes factors, which can be as large as 107 for some of the SBGs. Finally, we estimate the diffuse gamma-ray and neutrino fluxes of SFGs and SBGs, showing that they can explain $25{{\,\rm per\ cent}}$ of the diffuse HESE data while remaining consistent with gamma-ray limits on non-blazar sources.
Many extensions of the Standard Model predict the existence of new charged or neutral gauge bosons, with a wide variety of phenomenological implications depending on the model adopted. The search for ...such particles is extensively carried through at the Large Hadron Collider (LHC), and it is therefore of crucial importance to have for each proposed scenario quantitative predictions that can be matched to experiments. In this work we focus on the implications of one of these models, the top-flavor model (TF), proposing a charged W′ boson that has preferential couplings to the third-generation fermions. We compare such predictions to the ones from the so-called sequential Standard Model (SSM), that is used as benchmark, being one of the simplest and most commonly considered models for searches at the LHC. We identify the parameter space still open for searches at the LHC, and we show that the cross sections for the processes pp → W′ → τ ν and pp → W′ → t b in the TF assume different values with respect to the SSM as a function of the particle mass and width and that the TF has realizations that would not be allowed in the SSM and not yet excluded by data. This study makes the case for further searches at the LHC and shows how a complete and systematic model-independent analysis of W′ boson phenomenology at colliders is essential to provide guidance for future searches.
In the early universe, neutrinos are slightly coupled when electron–positron pairs annihilate transferring their entropy to photons. This process originates non-thermal distortions on the neutrino ...spectra which depend on neutrino flavour, larger for
ν
e
than for
ν
μ
or
ν
τ
. We study the effect of three-neutrino flavour oscillations on the process of neutrino decoupling by solving the momentum-dependent kinetic equations for the neutrino spectra. We find that oscillations do not essentially modify the total change in the neutrino energy density, giving
N
eff
=
3.046
in terms of the effective number of neutrinos, while the small effect over the production of primordial
4He is increased by
O
(
20
%
)
, up to
2.1
×
10
−4
. These results are stable within the presently favoured region of neutrino mixing parameters.
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