32,113 research outputs found
Novel Azimuthal Asymmetries in Drell Yan and Semi-inclusive Deep Inelastic Scattering
We consider the leading and sub-leading twist -odd and even contributions
to the azimuthal asymmetry in unpolarized dilepton production in
Drell-Yan Scattering. We estimate the contributions' effects at , , and energies in the framework of the
parton model using a quark diquark-spectator model of the nucleon to
approximate the soft contributions.Comment: 6 pages, 4 figure
Variance Reduction For A Discrete Velocity Gas
We extend a variance reduction technique developed by Baker and Hadjiconstantinou [1] to a discrete velocity gas. In our previous work, the collision integral was evaluated by importance sampling of collision partners [2]. Significant computational effort may be wasted by evaluating the collision integral in regions where the flow is in equilibrium. In the current approach, substantial computational savings are obtained by only solving for the deviations from equilibrium. In the near continuum regime, the deviations from equilibrium are small and low noise evaluation of the collision integral can be achieved with very coarse statistical sampling. Spatially homogenous relaxation of the Bobylev-Krook-Wu distribution [3,4], was used as a test case to verify that the method predicts the correct evolution of a highly non-equilibrium distribution to equilibrium. When variance reduction is not used, the noise causes the entropy to undershoot, but the method with variance reduction matches the analytic curve for the same number of collisions. We then extend the work to travelling shock waves and compare the accuracy and computational savings of the variance reduction method to DSMC over Mach numbers ranging from 1.2 to 10.Aerospace Engineering and Engineering Mechanic
An effective Hamiltonian for 2D black hole Physics
In another application of the methods of Henneaux, Teitelboim, and Vergara
developed for diffeomorphisms invariant models, the CGHS theory of 2D black
holes is focused in order to obtain the true degrees of freedom, the simplectic
structure and the {\it effective} Hamiltonian that rules the dynamics in
reduced phase-space.Comment: To appear in Europhysics Letter
Finite Order BFFT Method
We have proposed a method in the context of BFFT approach that leads to
truncation of the infinite series regarded to constraints in the extended phase
space, as well as other physical quantities (such as Hamiltonian). This has
been done for cases where the matrix of Poisson brackets among the constraints
is symplectic or constant. The method is applied to Proca model, single self
dual chiral bosons and chiral Schwinger models as examples.Comment: 14 pages, no figure to appear in Int. J. of Mod. Phys.
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