摘要:

A new approach to thermal quantum field theories based on renormalization group ideas is developed. Integrating out thermal loop corrections involving high energy particles results in a nonlocal effective Lagrangian for low energy particles. The approach is illustrated using thermal QED, and applications to thermal QCD are discussed.

ISSN:0094-243X    

DOI:10.1063/1.42603

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Electromagnetic lepton‐pair production in relativistic collisions is studied in anab initioapproach with no free parameters. After a semi‐classical approximation to the relative motion of the two incident particles is made, the resulting second‐order diagram is calculated using a Monte Carlo technique to evaluate the resulting seven‐dimensional integral. We examine the case of electron‐positron pair production in &pgr;−pcollisions atp&pgr;=17 GeV. We find that a significant fraction of the measured pairs in this reaction are produced via the magnetic spin‐flip current of the proton. Approaches, such as the equivalent photon approximation, which neglect this part of the current predict much too small a cross section. This feature is traced to the cuts imposed in taking the experimental data. Lepton‐pair production in the scattering of3He,4He and4He,4He is proposed as a clean way of experimentally separating the spin‐flip and non‐flip processes; predictions are made for these systems.

ISSN:0094-243X    

DOI:10.1063/1.42604

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

This talk reviews recent classical and quantum calculations of laser assisted dissociation and recombination of diatomic molecules. We treat the interaction of the laser field with the vibrational degree of freedom of the molecule. We emphasize the comparison of the classical and quantum mechanical solutions.

ISSN:0094-243X    

DOI:10.1063/1.42605

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

A new approach to study the real‐time behavior of non‐abelian lattice gauge theories off thermal equilibrium, based on Hamiltonian formalism is presented. The equations of motion are solved numerically in the semi‐classical limit. Several examples of the SU(2) lattice gauge dynamics are discussed: single plaquette system, the existence of periodic solution, instability of the color fields and chaotic behavior.

ISSN:0094-243X    

DOI:10.1063/1.42606

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

We present results from a Guided Random Walk Monte Carlo simulation of the lightq2q¯2system in a Coulomb‐plus‐linear quark potential model using an Intel iPSC/860 hypercube. A solvable model problem is first considered, after which we study the fullq2q¯2system in (J,I)=(2,2) and (2,0) sectors. We find evidence for no bound states below the vector‐vector threshold in these systems.

ISSN:0094-243X    

DOI:10.1063/1.42607

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

A formal structure for a calculable and covariant phenomenology of particles with arbitrary spin is presented. As wave equations for particles with high spin have difficulties, the construction proceeds without reference to any specific wave equation. The 2(2j+1) covariant particle/antiparticle spinors for any spin are explicitly constructed. These covariant spinors are then used to construct configuration, as well as momentum space, Feynman‐Dyson propagators for arbitrary spin.

ISSN:0094-243X    

DOI:10.1063/1.42608

出版商:AIP    

年代:1992

数据来源: AIP