arXiv subjects

A. Misaki

Publications and source records attributed to A. Misaki.

30 records · Page 2Linked to original sources

arXiv2005

Neutrinos from extragalactic cosmic ray interactions in the far infrared background

Extragalactic background of high energy neutrinos arising from the interactions of cosmic ray protons with far-infrared extragalactic background radiation is calculated. The main assumption is that the cosmic ray spectrum at energies higher than $10^8 GeV$ has extragalactic origin and, therefore, is proton dominated. All calculations are performed with taking into account the possible cosmological evolution of extragalactic sources of cosmic ray protons as well as infrared-luminous galaxies.

astro-ph↗

arXiv2005

Can One Extract the Neutrino Oscillation Signature from the SuperKamiokande Experiment ? An Analysis of Neutrino Events Occurring outside the Detector

The SuperKamiokande group assert that they have found an oscillatory signature in atmospheric neutrinos through the analysis of \textit{Fully Contained Events} and \textit{Partially Contained Events}. We have performed an $L/E$ (length/energy) analysis of \textit{Upward Through-Going Muon Events} and \textit{Stopping Muon Events} in a numerical computer simulations both with and without neutrino oscillations but were unable to find an oscillatory signature. We give likely explanations for the absence of the oscillatory signature in our simulations and its apparent presence in the SuperKamiokande data.

hep-ex↗

arXiv2004

The Zenith Angle Distribution of Fully Contained Events in SuperKamiokande and the Impact of Quasi Elastic Scattering on their Direction

Quasi Elastic Scattering (QEL) is the dominant mechanism for producing both Fully Contained Events and Partially Contained Events in the SuperKamiokande (SK) detector for atmospheric neutrinos in the range 0.1GeV to 10GeV. In the analysis of SK events, it is assumed that the zenith angle of the incident neutrino is the same as that of the detected charged lepton. In the present paper, we derive the distribution function for the scattering angle of charged leptons and derive the average scattering angles as well as their standard deviation due to QEL. Thus, it is shown that the SK assumption for the scattering angle of the charged lepton in QEL is not valid. Further, for a real analysis of the experimental data, we should examine the correlations between the zenith angle of the charged leptons and those of their incident neutrinos, taking into account the effect of the azimuthal angle of the charged particle over its zenith angle. We conclude that it is not possible to reliably assign the zenith angle of the incident neutrino to that of the charged lepton, and so the zenith angle distribution of charged leptons does not reflect that of the incident neutrinos under the SK assumption. This result has clear implication for attempts to detect neutrino oscillations from an analysis of Fully Contained Events and Partially Contained Events in SuperKamiokande.

astro-ph↗

arXiv2004

Have Superkamiokande Really Measured the Direction of the Atmospheric Neutrinos which Produce Fully Contained Events and Partially Contained Events ?

Quasi Elastic Scattering (QEL) is the dominant source for producing both Fully Contained Events and Partially Contained Events in the Superkamiokande(SK) detector for the atmospheric neutrinos, in the range 0.1 GeV to 10 GeV. In the analysis of SK events, it is assumed that the direction of the incident neutrino is the same as that of the detected charged lepton. In the present letter, we derive the distribution function for the scattering angle of the charged leptons, their averaged scattering angle and their standard deviation due to QEL. Then, it is shown that the SK assumption for the scattering angle of the charged leptons in the QEL is not valid. Further, we examine the influence of the azimuthal angle of the charged leptons over their zenith angle. As the result, we conclude that the zenith angle distribution of the neutrino under the SK assumption does not reflect the real zenith angle distribution of the atmospheric neutrino which produces Fully Contained Events and Partially Contained Events. This result has clear implication for attempts to detect neutrino oscillations from the analyses of Fully Contained Events and Partially Contained Events in Superkamiokande.

hep-ex↗

arXiv2003

Mass Composition of the Primary Cosmic Rays in the Energy Region 10^{14}-10^{20} eV in Anomalous Diffusion Model

We discuss the problem of cosmic ray mass composition variation in wide energy region 10^{14}-10^{20} eV. The mass composition predicted in the framework of recently developed anomalous diffusion model is tested using the results of CORSIKA calculations and experimental data on the depth of maximum of extensive air showers. We show that the model predictions for the mass composition are consistent with observations of different experiments.

astro-ph↗

arXiv2003

Fluxes of atmospheric muons underwater depending on the small-x gluon density

The prompt muon contribution to the deep-sea atmospheric muon flux can serve as a tool for probing into the small-x feature of the gluon density inside of a nucleon, if the muon energy threshold could be lifted to 100 TeV. The prompt muon flux underwater is calculated taking into consideration predictions of recent charm production models in which the small-x behaviour of the gluon distribution is probed. We discuss the possibility of distinguishing the PQCD models of the charm production differing in the small-x exponent of the gluon distribution, in measurements of the muon flux at energies 10-100 TeV with neutrino telescopes.

hep-ph↗

arXiv2001

Mean Square Radius of EAS Electrons

Detailed theoretical study of the mean square radius of extensive air shower electrons has been made in connection with further development of scaling formalism for electron lateral distribution function. A very simple approximation formula, which allows joint description of all our results obtained in wide primary energy range and for different observation depths is presented. The sensitivity of the mean square radius to variations of basic parameters of hadronic interaction model is discussed.

astro-ph↗

arXiv2001

The Shape of EAS Lateral Distribution and Primary Composition of the UHE Cosmic Rays

Theoretical predictions for lateral distribution function of electrons in extensive air showers based on scaling formalism are presented. Our results are tested by comparison with AGASA experimental data taking into account the contribution of low-energy muons and simultaneously the effect of scintillation detectors response, according to recent simulation results. The possibility for ultrahigh energy cosmic ray primary composition deduction from the shape of LDF is discussed in detail.

astro-ph↗

arXiv2001

Atmospheric muon fluxes underwater as a tool to probe the small-x gluon distribution

We compute deep-sea energy spectra and zenith-angle distributions of the atmospheric muons, both conventional and prompt. The prompt muon contribution to the muon flux underwater is calculated taking into consideration predictions of recent charm production models in which probed is the small-x behavior of the gluon distribution inside of a nucleon. We argue for a possibility to discriminate the PQCD models of the charm production differing in the slope of the gluon distribution, in measurements with neutrino telescopes of the muon flux at energies 10-100 TeV.

hep-ph↗

arXiv2000

Atmospheric Muon Flux at Sea Level, Underground, and Underwater

The vertical sea-level muon spectrum at energies above 1 GeV and the underground/underwater muon intensities at depths up to 18 km w.e. are calculated. The results are particularly collated with a great body of the ground-level, underground, and underwater muon data. In the hadron-cascade calculations, the growth with energy of inelastic cross sections and pion, kaon, and nucleon generation in pion-nucleus collisions are taken into account. For evaluating the prompt muon contribution to the muon flux, we apply two phenomenological approaches to the charm production problem: the recombination quark-parton model and the quark-gluon string model. To solve the muon transport equation at large depths of homogeneous medium, a semi-analytical method is used. The simple fitting formulas describing our numerical results are given. Our analysis shows that, at depths up to 6-7 km w. e., essentially all underground data on the muon intensity correlate with each other and with predicted depth-intensity relation for conventional muons to within 10%. However, the high-energy sea-level data as well as the data at large depths are contradictory and cannot be quantitatively decribed by a single nuclear-cascade model.

hep-ph↗

arXiv1999

Muon's Behaviors under Bremsstrahlung with both the LPM effect and the Ter-Mikaelian effect and Direct Pair Production with the LPM effect

Differential and integral cross sections of the muon are calculated in the materials: water, standard rock, iron and lead with and without the LPM effect. The corresponding cross sections are also calculated with dielectric supression effect (Ter-Mikaelian effect), in addition to the LPM effect. To demonstrate the importance of the LPM effect in the bremsstrahlung process, depth intensity relation of muon, energy spectrum, range distribution and survival probability are calculated taking into account bremsstrahlung spectrum.

hep-ph↗

arXiv1999

Expected Muon Energy Spectra and Zenithal Distributions Deep Underwater

Energy spectra and zenith angle distributions of atmospheric muons are calculated for the depths of operation of large underwater neutrino telescopes. The estimation of the prompt muon contribution is performed with three approaches to charm hadroproduction: recombination quark-parton model, quark-gluon string model, and perturbative QCD based models. Calculations show that the larger are zenith angles and water thickness above the detector, the lower is the energy at which the prompt muon flux becomes equal to conventional one (``crossing energy'') . For instance, for the depth of the Baikal Neutrino Telescope and for zenith angle of 78 degrees the crossing energy is about 300 TeV, whereas it is only 8 TeV for the NESTOR depth. Nevertheless, the muon flux of the crossing energy at NESTOR depth is in order of magnitude lower in comparison with the Baikal depth.

hep-ph↗