14 research outputs found
Performance and Simulation of the RICE detector
The RICE experiment (Radio Ice Cherenkov Experiment) at the South Pole,
co-deployed with the AMANDA experiment, seeks to detect ultra-high energy (UHE)
electron neutrinos interacting in cold polar ice. Such interactions produce
electromagnetic showers, which emit radio-frequency Cherenkov radiation. We
describe the experimental apparatus and the procedures used to measure the
neutrino flux.Comment: preprint, to be submitted to Astropart. Phy
Neutrino signatures of the supernova - gamma ray burst relationship
We calculate the TeV-PeV neutrino fluxes of gamma-ray bursts associated with
supernovae, based on the observed association between GRB 030329 and supernova
SN 2003dh. The neutrino spectral flux distributions can test for possible
delays between the supernova and the gamma-ray burst events down to much
shorter timescales than what can be resolved with photons. As an illustrative
example, we calculate the probability of neutrino induced muon and electron
cascade events in a km scale under-ice detector at the South Pole, from the GRB
030329. Our calculations demonstrate that km scale neutrino telescopes are
expected to detect signals that will allow to constrain supernova-GRB models.Comment: 7 pages, 2 figures. Accepted for publication in Phys. Rev.
Characterization of neutrino signals with radiopulses in dense media through the LPM effect
We discuss the possibilities of detecting radio pulses from high energy
showers in ice, such as those produced by PeV and EeV neutrino interactions. It
is shown that the rich radiation pattern structure in the 100 MHz to few GHz
allows the separation of electromagnetic showers induced by photons or
electrons above 100 PeV from those induced by hadrons. This opens up the
possibility of measuring the energy fraction transmitted to the electron in a
charged current electron neutrino interaction with adequate sampling of the
angular distribution of the signal. The radio technique has the potential to
complement conventional high energy neutrino detectors with flavor information.Comment: 5 pages, 4 ps figures. Submitted to Phys. Rev. Let
Systematics of Leading Particle Production
Using a QCD inspired model developed by our group for particle production,
the Interacting Gluon Model (IGM), we have made a systematic analysis of all
available data on leading particle spectra. These data include diffractive
collisions and photoproduction at HERA. With a small number of parameters
(essentially only the non-perturbative gluon-gluon cross section and the
fraction of diffractive events) good agreement with data is found. We show that
the difference between pion and proton leading spectra is due to their
different gluon distributions. We predict a universality in the diffractive
leading particle spectra in the large momentum region, which turns out to be
independent of the incident energy and of the projectile type.Comment: 13 pages, Latex, 4 ps figures. To appear in Phys. Rev.
Q2-evolution of parton densities at small-x values
In the leading twist approximation of the Wilson operator product expansion
with "frozen" and analytic strong coupling constants we show that
Bessel-inspired behavior of the structure function F2 at small x, obtained for
a flat initial condition in the DGLAP evolution equations, leads to good
agreement with the deep inelastic scattering experimental data from HERA.Comment: 19 pages, 5 figures, published in the Proceedings of Workshop on
Physics of Fundamental Interactions, Institute of High Energy Physics,
Protvino, Russia, 22--25 December 2008 (Phys.Atom.Nucl. in press
Angular Dependence of Neutrino Flux in KM3 Detectors in Low Scale Gravity Models
Cubic kilometer neutrino telescopes are capable of probing fundamental
questions of ultra-high energy neutrino interactions. There is currently great
interest in neutrino interactions caused by low-scale, extra dimension models.
Above 1 PeV the cross section in low scale gravity models rises well above the
total Standard Model cross section. We assess the observability of this effect
in the 1 PeV - 100 PeV energy range of kilometer-scale detectors with several
new points of emphasis that hinge on enhanced neutral current cross sections. A
major point is the importance of ``feed-down'' regeneration of upward neutrino
flux, driven by new-physics neutral current interactions in the flux evolution
equations. Feed-down is far from negligible, and it is essential to include its
effect. We then find that the angular distribution of events has high
discriminating value in separating models. In particular the ``up-to-down''
ratio between upward and downward-moving neutrino fluxes is a practical
diagnostic tool which can discriminate between models in the near future. The
slope of the angular distribution, in the region of maximum detected flux, is
also substantially different in low-scale gravity and the Standard Model. These
observables are only weakly dependent on astrophysical flux uncertainties. We
conclude that angular distributions can reveal a breakdown of the Standard
Model and probe the new physics beyond, as soon as data become available.Comment: 25 pages, 6 figures, discussion of calculations expanded, references
adde
Hard pomeron enhancement of ultrahigh-energy neutrino-nucleon cross-sections
An unknown small-x behavior of nucleon structure functions gives appreciable
uncertainties to high-energy neutrino-nucleon cross-sections. We construct
structure functions using at small x Regge inspired description by A. Donnachie
and P. V. Landshoff with soft and hard pomerons, and employing at larger x the
perturbative QCD expressions. The smooth interpolation between two regimes for
each Q^2 is provided with the help of simple polynomial functions. To obtain
low-x neutrino-nucleon structure functions and
singlet part of from Donnachie-Landshoff
function , we use the Q^2-dependent ratios R_2(Q^2) and
R_3(Q^2) derived from perturbative QCD calculations. Non-singlet part of F_3 at
low x, which is very small, is taken as power-law extrapolation of perturbative
function at larger x. This procedure gives a full set of smooth
neutrino-nucleon structure functions in the whole range of x and Q^2 at
interest.
Using these structure functions, we have calculated the neutrino-nucleon
cross-sections and compared them with some other cross-sections known in
literature. Our cross-sections turn out to be the highest among them at the
highest energies, which is explained by contribution of the hard pomeron.Comment: Final revised version, accepted by Phys. Rev. D; 18 pages, 7 figure
Estimating the inelasticity with the information theory approach
Using the information theory approach, in both its extensive and nonextensive
versions, we estimate the inelasticity parameter of hadronic reactions
together with its distribution and energy dependence from and
data. We find that the inelasticity remains essentially constant in energy
except for a variation around , as was originally expected.Comment: 14 pages, 8 figures. Misprints correcte
Dynamical parton distributions of the nucleon and very small-x physics
Utilizing recent DIS measurements (F_{2,L}) and data on dilepton and
high-E_{T} jet production we determine the dynamical parton distributions of
the nucleon generated radiatively from valence-like positive input
distributions at optimally chosen low resolution scales. These are compared
with `standard' distributions generated from positive input distributions at
some fixed and higher resolution scale. It is shown that up to the next to
leading order NLO(\bar{MS}, DIS) of perturbative QCD considered in this paper,
the uncertainties of the dynamical distributions are, as expected, smaller than
those of their standard counterparts. This holds true in particular in the
presently unexplored extremely small-x region relevant for evaluating ultrahigh
energy cross sections in astrophysical applications. It is noted that our new
dynamical distributions are compatible, within the presently determined
uncertainties, with previously determined dynamical parton distributions.Comment: 21 pages, 2 tables, 16 figures, v2: added Ref.[60], replaced Fig.