997 research outputs found
Elliptic Curve Scalar Multiplication Combining Yao’s Algorithm and Double Bases
Abstract. In this paper we propose to take one step back in the use of double base number systems for elliptic curve point scalar multiplication. Using a mod-ified version of Yao’s algorithm, we go back from the popular double base chain representation to a more general double base system. Instead of representing an integer k as Pn i=1 2 bi3ti where (bi) and (ti) are two decreasing sequences, we only set a maximum value for both of them. Then, we analyze the efficiency of our new method using different bases and optimal parameters. In particular, we pro-pose for the first time a binary/Zeckendorf representation for integers, providing interesting results. Finally, we provide a comprehensive comparison to state-of-the-art methods, including a large variety of curve shapes and latest point addition formulae speed-ups
Nuclear Structure Functions in the Large x Large Q^2 Kinematic Region in Neutrino Deep Inelastic Scattering
Data from the CCFR E770 Neutrino Deep Inelastic Scattering (DIS) experiment
at Fermilab contain events with large Bjorken x (x>0.7) and high momentum
transfer (Q^2>50 (GeV/c)^2). A comparison of the data with a model based on no
nuclear effects at large x, shows a significant excess of events in the data.
Addition of Fermi gas motion of the nucleons in the nucleus to the model does
not explain the excess. Adding a higher momentum tail due to the formation of
``quasi-deuterons'' makes some improvement. An exponentially falling F_2
\propto e^-s(x-x_0) at large x, predicted by ``multi-quark clusters'' and
``few-nucleon correlations'', can describe the data. A value of s=8.3 \pm
0.7(stat.)\pm 0.7(sys.) yields the best agreement with the data.Comment: 4 pages, 4 figures, 1 table. Sibmitted to PR
Determination of the Strange Quark Content of the Nucleon from a Next-to-Leading-Order QCD Analysis of Neutrino Charm Production
We present the first next-to-leading-order QCD analysis of neutrino charm
production, using a sample of 6090 - and -induced
opposite-sign dimuon events observed in the CCFR detector at the Fermilab
Tevatron. We find that the nucleon strange quark content is suppressed with
respect to the non-strange sea quarks by a factor \kappa = 0.477 \:
^{+\:0.063}_{-\:0.053}, where the error includes statistical, systematic and
QCD scale uncertainties. In contrast to previous leading order analyses, we
find that the strange sea -dependence is similar to that of the non-strange
sea, and that the measured charm quark mass, , is larger and consistent with that determined in other processes.
Further analysis finds that the difference in -distributions between
and is small. A measurement of the Cabibbo-Kobayashi-Maskawa
matrix element is also presented.
uufile containing compressed postscript files of five Figures is appended at
the end of the LaTeX source.Comment: Nevis R#150
Particle density fluctuations
Event-by-event fluctuations in the multiplicities of charged particles and
photons at SPS energies are discussed. Fluctuations are studied by controlling
the centrality of the reaction and rapidity acceptance of the detectors.
Results are also presented on the event-by-event study of correlations between
the multiplicity of charged particles and photons to search for DCC-like
signals.Comment: Talk presented at Quark Matter 2002, Nantes, Franc
Search for DCC in 158A GeV Pb+Pb Collisions
A detailed analysis of the phase space distributions of charged particles and
photons have been carried out using two independent methods. The results
indicate the presence of nonstatistical fluctuations in localized regions of
phase space.Comment: Talk at the PANIC99 Conference, June 9-16, 199
Central Pb+Pb Collisions at 158 A GeV/c Studied by Pion-Pion Interferometry
Two-particle correlations have been measured for identified negative pions
from central 158 AGeV Pb+Pb collisions and fitted radii of about 7 fm in all
dimensions have been obtained. A multi-dimensional study of the radii as a
function of kT is presented, including a full correction for the resolution
effects of the apparatus. The cross term Rout-long of the standard fit in the
Longitudinally CoMoving System (LCMS) and the vl parameter of the generalised
Yano-Koonin fit are compatible with 0, suggesting that the source undergoes a
boost invariant expansion. The shapes of the correlation functions in Qinv and
Qspace have been analyzed in detail. They are not Gaussian but better
represented by exponentials. As a consequence, fitting Gaussians to these
correlation functions may produce different radii depending on the acceptance
of the experimental setup used for the measurement.Comment: 13 pages including 10 figure
Present Status and Future of DCC Analysis
Disoriented Chiral Condensates (DCC) have been predicted to form in high
energy heavy ion collisions where the approximate chiral symmetry of QCD has
been restored. This leads to large imbalances in the production of charged to
neutral pions. Sophisticated analysis methods are being developed to
disentangle DCC events out of the large background of events with
conventionally produced particles. We present a short review of current
analysis methods and future prospects.Comment: 12 pages, 5 figures. Invited talk presented at the 13th International
Conference on Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter 97),
Tsukuba, Japan, 1-5 Dec 199
Search for Disoriented Chiral Condensates in 158 AGeV Pb+Pb Collisions
The restoration of chiral symmetry and its subsequent breaking through a
phase transition has been predicted to create regions of Disoriented Chiral
Condensates (DCC). This phenomenon has been predicted to cause anomalous
fluctuations in the relative production of charged and neutral pions in
high-energy hadronic and nuclear collisions. The WA98 experiment has been used
to measure charged and photon multiplicities in the central region of 158 AGeV
Pb+Pb collisions at the CERN SPS. In a sample of 212646 events, no clear DCC
signal can be distinguished. Using a simple DCC model, we have set a 90% C.L.
upper limit on the maximum DCC production allowed by the data.Comment: 20 Pages, LaTeX, uses elsart.cls, 8 eps figures included, submitted
to Physics Letters
Production of Pairs Accompanied by Nuclear Dissociation in Ultra-Peripheral Heavy Ion Collision
We present the first data on pair production accompanied by nuclear
breakup in ultra-peripheral gold-gold collisions at a center of mass energy of
200 GeV per nucleon pair. The nuclear breakup requirement selects events at
small impact parameters, where higher-order corrections to the pair production
cross section should be enhanced. We compare the pair kinematic distributions
with two calculations: one based on the equivalent photon approximation, and
the other using lowest-order quantum electrodynamics (QED); the latter includes
the photon virtuality. The cross section, pair mass, rapidity and angular
distributions are in good agreement with both calculations. The pair transverse
momentum, , spectrum agrees with the QED calculation, but not with the
equivalent photon approach. We set limits on higher-order contributions to the
cross section. The and spectra are similar, with no evidence
for interference effects due to higher-order diagrams.Comment: 6 pages with 3 figures Slightly modified version that will appear in
Phys. Rev.
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