摘要:

This talk describes work in progress on the subject of virtual QCD corrections to top production and decay ate+e−colliders. We examine the resonant behavior of the amplitudes that dominate the cross section and discuss implementation in a Monte Carlo program. The theoretical framework is similar to that which has been successfully applied for QED corrections toWpair production at LEP II. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1328907

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

In this paper we investigate a many body problem which shares the same features as QCD, in the large N limit. Solving it could help us to better understand why the quarks are confined. We analyze some possible ways of dealing with this problem when the number of chain gluons in very large. The results suggest that the macroscopic potential of a large chain is a confining potential, whatever the microscopic potential is. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1328908

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

We construct highest weight unitary irreducible representations of a Lie algebra for open quantum matrix chains akin to quotients of Verma modules for simple finite-dimensional Lie algebras. Those representations resembling typical unitary irreducible representations ofgl(n)turn out to be tensor products of the defining representation. They can be physically identified as multiple meson states or multiple open string states. Other representations are intimately related to the Cuntz algebra. They may be related to novel bound states. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1328909

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

In this article we propose a new method of describing instantons of certain dynamical systems whose phase spaces are not cotangent bundles. Our method relies heavily on the idea of J Holomorphic Curves first introduced by M. Gromov in 1985. We illustrate our method by applying it to the rigid body dynamics. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1328910

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

We review our recent results on higher order corrections in positronium physics. We discuss a calculation of the recoilO(m&agr;6)corrections to the hyperfine splitting [1] and energy levels [2] of a positronium atom,O(m&agr;7&hthinsp;ln2&hthinsp;&agr;)contributions to the positroniumS-wave energy levels [3] andO(&agr;2)radiative corrections to the parapositronium decay rate [4]. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1328911

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

Advantages of using a low-energy effective theory to study bound state properties are briefly discussed, and a nonperturbative implementation of such an effective theory is described within the context of nonrelativistic quantum mechanics. The hydrogen atom, in the approximation of a structureless, infinite-mass nucleus, but with the leading relativistic and radiative corrections included, is used to demonstrate the construction and solution of the effective theory. The resulting Hamiltonian incorporates a finite ultraviolet cutoff and can be solved nonperturbatively. An appendix lists explicit formulas for the various matrix elements necessary to diagonalize the Hamiltonian using gaussian basis sets. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1328912

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

In this talk we describe a novel method for the renormalization of the Hamiltonian operator in Quantum Field Theory in the spirit of the Wilson renormalization group [1]. By a series of unitary transformations that successively decouple the high-frequency degrees of freedom and partially diagonalizes the high-energy part, we obtain the effective Hamiltonian for the low energy degrees of freedom. Using this technique we study&lgr;&fgr;4theory at two loops. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1328913

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

Two dimensional Quantum HadronDynamics is a bi-local gauge invariant reformulation of two dimensional QCD, introduced by one of us. The baryon arises as a topological soliton in this picture. Here we study the baryon number one sector of HadronDynamics. Starting from the soliton picture, we derive an interacting quark model, thus reconciling these two seemingly different approaches. The valence quark model arises as a variational approximation to HadronDynamics. We find a succession of better approximations to the soliton picture. The next simplest case that improves on the valence quark approximation turns out to correspond to a system of interacting valence, ‘sea’ and anti-quarks. We also obtain this ‘embellished’ quark model directly from the valence quark system through a Bogoliubov transformation. Using the solitonic point of view, we estimate the quark and anti-quark distributions of 2d QCD. We point out possible applications to the baryon structure functions measured in Deep Inelastic Scattering. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1328914

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

We discuss vector boson production at hadron colliders and the treatment of the initial-state radiation according to Monte Carlo parton shower simulations and resummed calculations. In particular, we investigate the effect of matrix-element corrections to the HERWIG event generator onW/Ztransverse momentum distributions. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1328915

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

The Standard Model amplitudes for processes where one or more gauge bosons are emitted exhibit zeros in the angular distributions. The theoretical and experimental aspects of these radiation amplitude zeros are reviewed and some recent results are discussed. It is shown that radiation zeros can be explained as a result of the factorization of the amplitudes as well as a consequence of the decoupling theorem. It is briefly explained how radiation zeros can be used to test the SM. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1328916

出版商:AIP    

年代:1900

数据来源: AIP