2,013 research outputs found
Cosmogenic neutrino fluxes under the effect of active-sterile secret interactions
Ultra High Energy cosmogenic neutrinos may represent a unique opportunity to
unveil possible new physics interactions once restricted to the neutrino sector
only. In the present paper we study the observable effects of a secret
active-sterile interactions, mediated by a pseudoscalar, on the expected flux
of cosmogenic neutrinos. The results show that for masses of sterile neutrinos
and pseudoscalars of hundreds MeV, necessary to evade cosmological,
astrophysical and elementary particle constraints, the presence of such new
interactions can significantly change the energy spectrum of cosmogenic
neutrinos at Earth in the energy range from PeV to ZeV. Interestingly, the
distortion of the spectrum results to be detectable at GRAND apparatus if the
scalar mediator mass is around 250 MeV and the UHECRs are dominated by the
proton component. Larger mediator masses or a chemical composition of UHECRs
dominated by heavier nuclei would require much larger cosmic rays apparatus
which might be available in future.Comment: 10 pages, 3 figure
Slow and fast collective neutrino oscillations: Invariants and reciprocity
The flavor evolution of a neutrino gas can show ''slow'' or ''fast''
collective motion. In terms of the usual Bloch vectors to describe the
mean-field density matrices of a homogeneous neutrino gas, the slow two-flavor
equations of motion (EOMs) are
,
where , , is a unit vector in the mass direction in
flavor space, and . For an
axisymmetric angle distribution, the fast EOMs are
, where
is the Bloch vector for lepton number, is the
velocity along the symmetry axis, , and
. We discuss similarities and differences
between these generic cases. Both systems can have pendulum-like instabilities
(soliton solutions), both have similar Gaudin invariants, and both are
integrable in the classical and quantum case. Describing fast oscillations in a
frame comoving with (which itself may execute pendulum-like
motions) leads to transformed EOMs that are equivalent to an abstract slow
system. These conclusions carry over to three flavors.Comment: 16 pages; typo below Eq. (5) and in Eq. (47) correcte
Bump-hunting in the diffuse flux of high-energy cosmic neutrinos
The origin of the bulk of the high-energy astrophysical neutrinos seen by
IceCube, with TeV--PeV energies, is unknown. If they are made in photohadronic,
i.e., proton-photon, interactions in astrophysical sources, this may manifest
as a bump-like feature in their diffuse flux, centered around a characteristic
energy. We search for evidence of this feature, allowing for variety in its
shape and size, in 7.5 years of High-Energy Starting Events (HESE) collected by
the IceCube neutrino telescope, and make forecasts using larger data samples
from upcoming neutrino telescopes. Present-day data reveals no evidence of
bump-like features, which allows us to constrain candidate populations of
photohadronic neutrino sources. Near-future forecasts show promising potential
for stringent constraints or decisive discovery of bump-like features. Our
results provide new insight into the origins of high-energy astrophysical
neutrinos, complementing those from point-source searches.Comment: 29 pages, 13 figure
Hunting for bumps in the diffuse high-energy neutrino flux
The origin of the TeV--PeV astrophysical neutrinos seen by the IceCube
telescope is unknown. If they are made in proton-photon interactions in
astrophysical sources, their spectrum may show bump-like features. We search
for such features in the 7.5-years High-Energy Starting Events (HESE), and
forecast the power of such searches using larger data samples expected from
upcoming telescopes. Present-day data reveals no evidence of bump-like
features, which allows us to constrain candidate populations of photohadronic
neutrino sources. Near-future forecasts show promising potential for stringent
constraints or decisive discovery of bump-like features. Our results provide
new insight into the origins of high-energy astrophysical neutrinos,
complementing those from point-source searches.Comment: Submitted as a proceeding for ICRC 2023. arXiv admin note:
substantial text overlap with arXiv:2301.0002
Asymmetric decentralization: distortions and opportunities
none3This paper studies the interplay between central and local governments in defining the optimal degree of decentralization in terms of public goods supply. The choice between full centralization and asymmetric decentralization implies a trade-off between the possibility to provide public goods at a lower cost, wherever this is possible by decentralizing, and the possibility to fully internalize spillovers by full centralization. We find that asymmetric decentralization introduces distortions into the public decision-making process. We also demonstrate that the power to interfere in the central government’s ruling mechanisms should be reduced for the jurisdictions that have decentralized, in order to make their decentralization choice convenient even for the citizens in the less efficient jurisdictions. Finally, we find the conditions under which asymmetric decentralization can be simultaneously advantageous for both rich and poor regions through the design of appropriate equalization transfers.openFiorillo F.; Giuranno M.G.; Sacchi A.Fiorillo, F.; Giuranno, M. G.; Sacchi, A
The GAP-TPC
Several experiments have been conducted worldwide, with the goal of observing
low-energy nuclear recoils induced by WIMPs scattering off target nuclei in
ultra-sensitive, low-background detectors. In the last few decades noble liquid
detectors designed to search for dark matter in the form of WIMPs have been
extremely successful in improving their sensitivities and setting the best
limits. One of the crucial problems to be faced for the development of large
size (multi ton-scale) liquid argon experiments is the lack of reliable and low
background cryogenic PMTs: their intrinsic radioactivity, cost, and borderline
performance at 87 K rule them out as a possible candidate for photosensors. We
propose a brand new concept of liquid argon-based detector for direct dark
matter search: the Geiger-mode Avalanche Photodiode Time Projection Chamber
(GAP-TPC) optimized in terms of residual radioactivity of the photosensors,
energy and spatial resolution, light and charge collection efficiencyComment: 7 pages, 5 figures, Accepted for publication on JINS
AIF-1 gene does not confer susceptibility to Behçet's disease: Analysis of extended haplotypes in Sardinian population
Background BehcEet's disease (BD) is a polygenic immune-mediated disorder characterized by a close association with the HLA-B∗51 allele. The HLA region has a strong linkage disequilibrium (LD) and carries several genetic variants (e.g. MIC-A, TNF-α genes) identified as associated to BD because of their LD with HLA-B∗51. In fact, the HLA-B∗51 is inherited as part of extended HLA haplotypes which are well preserved in patients with BD. Sardinian population is highly differentiated from other Mediterranean populations because of a distinctive genetic structure with very highly preserved HLA haplotypes. Patients and methods In order to identify other genes of susceptibility to BD within the HLA region we investigated the distribution of human Allograft Inflammatory Factor-1 (AIF-1) gene variants among BD patients and healthy controls from Sardinia. Six (rs2736182; rs2259571; rs2269475; rs2857597; rs13195276; rs4711274) AIF-1 single nucleotide polymorphisms (SNPs) and related extended haplotypes have been investigated as well as their LD within the HLA region and with HLA-B∗51. Overall, 64 BD patients, 43 HLA-B∗51 positive healthy controls (HC) and 70 random HC were enrolled in the study. Results HLA-B∗51 was the only allele with significantly higher frequency (pc = 0.0021) in BD patients (40.6%) than in HC (9.8%). The rs2259571TAIF-1 variant had a significantly reduced phenotypic, but not allelic frequency in BD patients (72.1%; pc = 0.014) compared to healthy population (91.3%). That was likely due to the LD between HLA-B∗51 and rs2259571G(pc= 9E-5), even though the rs2259571Gdistribution did not significantly differ between BD patients and HC. Conclusion No significant difference in distribution of AIF-1 SNPs haplotypes was observed between BD patients and HC and between HLA-B∗51 positive BD patients and HLA-B∗51 positive HC. Taken together, these results suggest that AIF-1 gene is not associated with susceptibility to BD in Sardinia
VUV-Vis optical characterization of Tetraphenyl-butadiene films on glass and specular reflector substrates from room to liquid Argon temperature
The use of efficient wavelength-shifters from the vacuum-ultraviolet to the
photosensor's range of sensitivity is a key feature in detectors for Dark
Matter search and neutrino physics based on liquid argon scintillation
detection. Thin film of Tetraphenyl-butadiene (TPB) deposited onto the surface
delimiting the active volume of the detector and/or onto the photosensor
optical window is the most common solution in current and planned experiments.
Detector design and response can be evaluated and correctly simulated only when
the properties of the optical system in use (TPB film + substrate) are fully
understood. Characterization of the optical system requires specific, sometimes
sophisticated optical methodologies. In this paper the main features of TPB
coatings on different, commonly used substrates is reported, as a result of two
independent campaigns of measurements at the specialized optical metrology labs
of ENEA and University of Tor Vergata. Measured features include TPB emission
spectra with lineshape and relative intensity variation recorded as a function
of the film thickness and for the first time down to LAr temperature, as well
as optical reflectance and transmittance spectra of the TPB coated substrates
in the wavelength range of the TPB emission
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