95,668 research outputs found
The Virtual Monte Carlo
The concept of Virtual Monte Carlo (VMC) has been developed by the ALICE
Software Project to allow different Monte Carlo simulation programs to run
without changing the user code, such as the geometry definition, the detector
response simulation or input and output formats. Recently, the VMC classes have
been integrated into the ROOT framework, and the other relevant packages have
been separated from the AliRoot framework and can be used individually by any
other HEP project. The general concept of the VMC and its set of base classes
provided in ROOT will be presented. Existing implementations for Geant3, Geant4
and FLUKA and simple examples of usage will be described.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics
(CHEP03), La Jolla, Ca, USA, March 2003, 8 pages, LaTeX, 6 eps figures. PSN
THJT006. See http://root.cern.ch/root/vmc/VirtualMC.htm
Multilevel Richardson-Romberg extrapolation
We propose and analyze a Multilevel Richardson-Romberg (MLRR) estimator which
combines the higher order bias cancellation of the Multistep Richardson-Romberg
method introduced in [Pa07] and the variance control resulting from the
stratification introduced in the Multilevel Monte Carlo (MLMC) method (see
[Hei01, Gi08]). Thus, in standard frameworks like discretization schemes of
diffusion processes, the root mean squared error (RMSE) can
be achieved with our MLRR estimator with a global complexity of
instead of with the standard MLMC method, at least when the weak
error of the biased implemented estimator
can be expanded at any order in and . The MLRR estimator is then halfway between a regular MLMC
and a virtual unbiased Monte Carlo. When the strong error , , the gain of MLRR over MLMC becomes even
more striking. We carry out numerical simulations to compare these estimators
in two settings: vanilla and path-dependent option pricing by Monte Carlo
simulation and the less classical Nested Monte Carlo simulation.Comment: 38 page
Theoretical improvements for luminosity monitoring at low energies
A comparison of theoretical results on NNLO leptonic and hadronic corrections
to Bhabha scattering with the Monte Carlo generator BabaYaga@NLO used at meson
factories is given. Complete NLO virtual corrections to the process are discussed.Comment: 8 pages, 4 figs, presented by J.Gluza at Radcor 201
Radiation therapy calculations using an on-demand virtual cluster via cloud computing
Computer hardware costs are the limiting factor in producing highly accurate
radiation dose calculations on convenient time scales. Because of this,
large-scale, full Monte Carlo simulations and other resource intensive
algorithms are often considered infeasible for clinical settings. The emerging
cloud computing paradigm promises to fundamentally alter the economics of such
calculations by providing relatively cheap, on-demand, pay-as-you-go computing
resources over the Internet. We believe that cloud computing will usher in a
new era, in which very large scale calculations will be routinely performed by
clinics and researchers using cloud-based resources. In this research, several
proof-of-concept radiation therapy calculations were successfully performed on
a cloud-based virtual Monte Carlo cluster. Performance evaluations were made of
a distributed processing framework developed specifically for this project. The
expected 1/n performance was observed with some caveats. The economics of
cloud-based virtual computing clusters versus traditional in-house hardware is
also discussed. For most situations, cloud computing can provide a substantial
cost savings for distributed calculations.Comment: 12 pages, 4 figure
Radiative Corrections to High Energy Lepton Bremsstrahlung on Heavy Nuclei
One-loop radiative corrections to the leptonic tensor in high energy
bremsstrahlung on heavy nuclei are calculated. Virtual and real photon
radiation is taken into account. Double bremsstrahlung is simulated by means of
Monte Carlo. Numerical results are presented for the case of muon
bremsstrahlung in conditions of the COMPASS experiment at CERN.Comment: 7 pages, 1 figur
Forward hadron production in ultraperipheral proton-heavy-ion collisions at the LHC and RHIC
We discuss hadron production in the forward rapidity region in
ultraperipheral proton-lead collisions at the LHC and proton-gold collisions at
RHIC. Our discussion is based on the Monte Carlo simulations of the
interactions of virtual photons emitted by a fast moving nucleus with a proton
beam. We simulate the virtual photon flux with the STARLIGHT event generator
and then particle production with the SOPHIA, DPMJET, and PYTHIA event
generators. We show the rapidity distributions of charged and neutral
particles, and the momentum distributions of neutral pions and neutrons at
forward rapidities. According to the Monte Carlo simulations, we find large
cross sections of ultraperipheral collisions for particle production especially
in the very forward region, leading to substantial background contributions to
investigations of collective nuclear effects and spin physics. Finally we can
distinguish between proton-nucleus inelastic interactions and ultraperipheral
collisions with additional requirements of either of the charged particles at
midrapidity and a certain level of activities at negative forward rapidity.Comment: 9 pages, 4 figures, 2 tabl
Forward Jet Production at HERA
We discuss forward jet production data recently published by the H1 and ZEUS
collaborations at HERA. We review how several Monte-Carlo models compare to the
data. QCD calculations based on the BFKL formalism and on fixed NLO
perturbation theory with and without resolved virtual photons are described.Comment: 10 pages, 4 eps figures; talk given at the Ringberg Workshop 'New
Trends in HERA Physics 1999
The radiative return at small angles: virtual corrections
Virtual corrections for electron--positron annihilation into one real and one
off-shell photon of invariant mass Q^2 are evaluated. Special attention is paid
to those configurations where the real photon is collinear with the beam
direction. This calculation is an important ingredient of a Monte Carlo
program, which simulates events with tagged photons from initial-state
radiation, including NLO corrections.Comment: 8 pages, 2 figure
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