摘要:

We find exact results for Grover’s quantum search algorithm and analyze its behavior under noisy situations when no quantum correction codes are available. We compute how the algorithm slows down: it is still better than a classical one, provided the noise is smaller than some bound, which we also compute. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1301410

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

Ultra High Energy Cosmic Rays events beyond the theoretical cutoff of1019&hthinsp;eVhave been detected by several experiments. Nevertheless we do not know any potential astronomical source which could accelerate particles to those energies. We discuss new ideas for the production of these events, the so called “top-down” mechanisms, which involve exotic relics of the early universe. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1301411

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

We present the available list of Kac-Moody levels coming from Grand Unified Theories (GUTs), with the aim to look for new insights in the four dimensional supersymmetric (SUSY) strings. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1301412

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

Chiral Ward identities lead to consistent accounting for the &sgr;’s width in the linear sigma model’s Feynman rules. Reanalysis of pion scattering data at threshold imply a mass for the &sgr; of600−100+200&hthinsp;MeV.©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1301413

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

We investigate the processe+e−→W+W−,currently being studied at LEP, in the context of the simplest extension of the Standard Model of electroweak interactions, where a singlet right-handed neutrino is added to the matter content of the model. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1301414

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

We present a particular approach to the non-equilibrium dynamics of quantum field theory. This approach is based on the Jaynes-Gibbs principle of the maximal entropy and its implementation, throughout the initial-value data, into the dynamical equations for Green’s functions. We use the&fgr;4theory in the largeNlimit to show how our method works by calculating the pressure for a system which is invariant under both spatial and temporal translations. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1301415

出版商:AIP    

年代:1999

数据来源: AIP

摘要:

We examine the relation between the damping rate of a fermionic mode propagating in a hot QED or QCD plasma, and the corresponding reaction rate. We show that these two quantities should be equal provided the reaction rate is calculated using properly normalized wave functions for the mode in the medium. We use finite temperature cutting rules to identify the different terms in the expression for the damping rate with physical processes in the plasma. ©1999 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1301416

出版商:AIP    

年代:1999

数据来源: AIP