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تسجيل مستخدم جديدA charming ICECUBE discover?
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Last two years high energy neutrino data are studied. The two recent tau neutrino double bang candidate are discussed within their detectability, noise and expected rate. The neutrino flavor distribution mainly favoring equal electron and muon presence, is reminded. The angular distribution of highest muon neutrino tracks is analyzed. Their horizontal strong anisotropy and their remarkable up-down asymmetry, with the absence of clustering, is noticed. The main persistent missing of astrophysical X,gamma sources (as GRB and AGN flaring source) and all the above signatures led us to suggest a dominance of prompt charmed (atmospheric) events able to pollute, to smear and to hide any minor astronomical presence.
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During the first three flights of the Antarctic Impulsive Transient Antenna (ANITA) experiment, the collaboration detected several neutrino candidates. Two of these candidate events were consistent with an ultra-high-energy up-going air shower and co
mpatible with a tau neutrino interpretation. A third neutrino candidate event was detected in a search for Askaryan radiation in the Antarctic ice, although it is also consistent with the background expectation. The inferred emergence angle of the first two events is in tension with IceCube and ANITA limits on isotropic cosmogenic neutrino fluxes. Here, we test the hypothesis that these events are astrophysical in origin, possibly caused by a point source in the reconstructed direction. Given that any ultra-high-energy tau neutrino flux traversing the Earth should be accompanied by a secondary flux in the TeV-PeV range, we search for these secondary counterparts in seven years of IceCube data using three complementary approaches. In the absence of any significant detection, we set upper limits on the neutrino flux from potential point sources. We compare these limits to ANITAs sensitivity in the same direction and show that an astrophysical explanation of these anomalous events under standard model assumptions is severely constrained regardless of source spectrum.
At very-high energies (100 TeV - 1 PeV), the small value of Bjorken-x ($le10^{-3}-10^{-7}$) at which the parton distribution functions are evaluated makes the calculation of charm quark production very difficult. The charm quark has mass ($sim$1.5$pm
$0.2 GeV) significantly above the $Lambda$$_{QCD}$ scale ($sim$200 MeV), and therefore its production is perturbatively calculable. However, the uncertainty in the data and the calculations cannot exclude some smaller non-perturbative contribution. To evaluate the prompt neutrino flux, one needs to know the charm production cross-section in pN -> c$bar{c}$ X, and hadronization of charm particles. This contribution briefly discusses computation of prompt neutrino flux and presents the strongest limit on prompt neutrino flux from IceCube.
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 t
he 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-year High-Energy Starting Events (HESE) and the 6-year 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 $40%$ of the HESE events at $95.4%$ 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 modeling of astrophysical sources could alleviate the tension between neutrino and gamma-ray data interpretation.
We present a flavor and energy inference analysis for each high-energy neutrino event observed by the IceCube observatory during six years of data taking. Our goal is to obtain, for the first time, an estimate of the posterior probability distributio
n for the most relevant properties, such as the neutrino energy and flavor, of the neutrino-nucleon interactions producing shower and track events in the IceCube detector. For each event the main observables in the IceCube detector are the deposited energy and the event topology (showers or tracks) produced by the Cherenkov light by the transit through a medium of charged particles created in neutrino interactions. It is crucial to reconstruct from these observables the properties of the neutrino which generated such event. Here we describe how to achieve this goal using Bayesian inference and Markov chain Monte Carlo methods.
We study odd-parity baryonic resonances with one heavy and three light flavors, dynamically generated by meson-baryon interactions. Special attention is paid to Heavy Quark Spin Symmetry (HQSS), hence pseudoscalar and vector mesons and baryons with J
^P = 1/2+ and 3/2+ are considered as constituent hadrons. For the hidden-charm sector (N-c-quarks = N-c-antiquarks = 1), the meson-baryon Lagrangian with Heavy Flavor Symmetry is constructed by a minimal extension of the SU(3) Weinberg-Tomozawa (WT) Lagrangian to fulfill HQSS, such that not new parameters are needed. This interaction can be presented in different formal ways: as a Field Lagrangian, as Hadron creation-annihilation operators, as SU(6)xHQSS group projectors and as multichannel matrices. The multichannel Bethe-Salpeter equation is solved for odd-parity light baryons, hidden-charm N and Delta and Beauty Baryons (Lambda-b). Results of calculations with this model are shown in comparison with other models and experimental values for baryonic resonances.
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