1,530 research outputs found
Tau Neutrino Astronomy in GeV Energies
We point out the opportunity of the tau neutrino astronomy for the neutrino
energy E ranging between 10 GeV and 10^3 GeV. In this energy range, the
intrinsic tau neutrino production is suppressed relative to the intrinsic muon
neutrino production. Any sizable tau neutrino flux may thus arise because of
the \nu_{\mu}\to \nu_{\tau} neutrino oscillations only. It is demonstrated
that, in the presence of the neutrino oscillations, consideration of the
neutrino flavor dependence in the background atmospheric neutrino flux leads to
the drastically different prospects between the observation of the
astrophysical muon neutrinos and that of the astrophysical tau neutrinos.
Taking the galactic-plane neutrino flux as the targeted astrophysical source,
we have found that the galactic-plane tau neutrino flux dominates over the
atmospheric tau neutrino flux for E > 10 GeV. Hence, the galactic-plane can at
least in principle be seen through the tau neutrinos with energies just greater
than 10 GeV. In a sharp contrast, the galactic-plane muon neutrino flux is
overwhelmed by its atmospheric background until E > 10^6 GeV.Comment: major revision of text and two new figures, to appear in PR
Atmospheric neutrino flux at INO, South Pole and Pyh\"asalmi
We present the calculation of the atmospheric neutrino fluxes for the
neutrino experiments proposed at INO, South Pole and Pyh\"asalmi. Neutrino
fluxes have been obtained using ATMNC, a simulation code for cosmic ray in the
atmosphere. Even using the same primary flux model and the interaction model,
the calculated atmospheric neutrino fluxes are different for the different
sites due to the geomagnetic field. The prediction of these fluxes in the
present paper would be quite useful in the experimental analysis.Comment: 12Pages,9Fig
Neutrino Induced Upward Going Muons from a Gamma Ray Burst in a Neutrino Telescope of Km^2 Area
The number of neutrino induced upward going muons from a single Gamma Ray
Burst (GRB) expected to be detected by the proposed kilometer scale IceCube
detector at the South Pole location has been calculated. The effects of the
Lorentz factor, total energy of the GRB emitted in neutrinos and its distance
from the observer (red shift) on the number of neutrino events from the GRB
have been examined. The present investigation reveals that there is possibility
of exploring the early Universe with the proposed kilometer scale IceCube
neutrino telescope.Comment: 18pages, 5 figures. Physical Review D in pres
Semileptonic B Decays and Determination of |Vub|
Semileptonic decays of the B mesons provide an excellent probe for the weak
and strong interactions of the bottom quark. The large data samples collected
at the B Factories have pushed the experimental studies of the semileptonic B
decays to a new height and stimulated significant theoretical developments. I
review recent progresses in this fast-evolving field, with an emphasis on the
determination of the magnitude of the Cabibbo-Kobayashi-Maskawa matrix element
|Vub|.Comment: 16 pages, 4 figures, accepted by Mod. Phys. Lett.
Potential Operation and Maintenance (O&M) Savings in the John Sealy North Building at UTMB
The LoanSTAR Monitoring and Analysis Group, Energy Systems Laboratory at Texas A&M University, was requested by University of Texas Medical Branch at Galveston to investigate O&M measures in their five LoanSTAR program buildings. This report describes the suggested O&Ms in John Sealy North Building, a surgical building of 54,494 ft2,which currently spends 502,100 per year on electricity, steam and chilled water. The suggested O&Ms include optimizing the outside air treatment cold deck reset schedule, the cold deck reset schedule and the hot deck reset schedule. These optimized HVAC operation schedules were determined using an analysis involving a simplified HVAC model, which was calibrated against daily data measured by the LoanSTAR program. It is estimated that annual savings of 67,000, or 13% of the annual costs, can be realized using the optimized operation schedules which can be implemented without additional costs. Our analysis indicates that the room comfort levels will not be degraded by these measures
Theoretical study of lepton events in the atmospheric neutrino experiments at SuperK
Super-Kamiokande has reported the results for the lepton events in the
atmospheric neutrino experiment. These results have been presented for a 22.5kT
water fiducial mass on an exposure of 1489 days, and the events are divided
into sub-GeV, multi-GeV and PC events. We present a study of nuclear medium
effects in the sub-GeV energy region of atmospheric neutrino events for the
quasielastic scattering, incoherent and coherent pion production processes, as
they give the most dominant contribution to the lepton events in this energy
region. We have used the atmospheric neutrino flux given by Honda et al. These
calculations have been done in the local density approximation. We take into
account the effect of Pauli blocking, Fermi motion, Coulomb effect,
renormalization of weak transition strengths in the nuclear medium in the case
of the quasielastic reactions. The inelastic reactions leading to production of
leptons along with pions is calculated in a - dominance model by
taking into account the renormalization of properties in the nuclear
medium and the final state interaction effects of the outgoing pions with the
residual nucleus. We present the results for the lepton events obtained in our
model with and without nuclear medium effects, and compare them with the Monte
Carlo predictions used in the simulation and the experimentally observed events
reported by the Super-Kamiokande collaboration.Comment: 23 pages, 13 figure
Neutrino propagation in a random magnetic field
The active-sterile neutrino conversion probability is calculated for neutrino
propagating in a medium in the presence of random magnetic field fluctuations.
Necessary condition for the probability to be positive definite is obtained.
Using this necessary condition we put constraint on the neutrino magnetic
moment from active-sterile electron neutrino conversion in the early universe
hot plasma and in supernova.Comment: 11 page
High Energy Neutrino Signals of Four Neutrino Mixing
We evaluate the upward shower and muon event rates for two characteristic
four neutrino mixing models for extragalactic neutrinos, as well as for the
atmospheric neutrinos, with energy thresholds of 1 TeV, 10 TeV and 100 TeV. We
show that by comparing the shower to muon event rates, one can distinguish
between oscillation and no-oscillation models. By measuring shower and muon
event rates for energy thresholds of 10 TeV and 100 TeV, and by considering
their ratio, it is possible to use extragalactic neutrino sources to determine
the type of four-flavor mixing pattern. We find that one to ten years of data
taking with kilometer-size detector has a very good chance of providing
valuable information about the physics beyond the Standard Model.Comment: version accepted for publication in Phys. Rev.
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