相关论文: Valley Bifurcation in an $O(3)$ $\sigma$ Model: Im…
We consider the valley--method computation of the inclusive cross section of baryon number violating processes in the Standard Model. We show that any physically correct model of the valley action should present a singularity in the saddle…
Problems related to fermions, unitarity and chiral anomaly in high energy electroweak interactions, are investigated. Particular attention is paid to the correct functional integration over fermion fields in the background of…
We study the level crossing of the fermion system described by the euclidean Dirac Hamiltonian in the valley background. One chiral fermion level is shown to cross twice the zero value in the case of well-separated instanton-anti-instanton…
We calculate the cross sections of the baryon and lepton number violating processes. The proper valley method enables us to calculate the multi-boson processes, which have the possibility to observation. The mass corrections of the gauge…
We evaluate the eigenvalues of Dirac operator in the background of instanton-anti-instanton configuration (I-$\bar{{\rm I}}$), in a simple (1+0)-dimensional model, and find that quasi-zero-mode disappears for the closely localized…
We develop a systematic treatment for the quasi-zero modes, which play an important role in nonabelian gauge theories. It can be used to derive the analytic forms for the constrained instantons in the \ymh theory. This will automatically…
We compare the two most popular approaches to the problem of instanton-antiinstanton interaction at high energies - the valley method and the effective-Lagrangian approach - and use them to calculate the next-to-next-to-leading term in the…
We review some promising numerical techniques for calculating high energy baryon number violating cross sections in the standard model. As these lectures are designed to be self- contained, we present in some detail the formalism of…
We use semiclassical methods to study processes which give rise to change of topology and therefore to baryon number violation in the standard model. We consider classically allowed processes, i.e.~energies above the sphaleron barrier. We…
The elucidation of the properties of the instantons in the topologically trivial sector has been a long-standing puzzle. Here we claim that the properties can be summarized in terms of the geometrical structure in the configuration space,…
Winding number transitions in the two dimensional softly broken O(3) nonlinear sigma model are studied at finite energy and temperature. New periodic instanton solutions which dominate the semiclassical transition amplitudes are found…
We present some recent advances in the computational study of baryon number violation in high energy electroweak collisions. We examine classically allowed processes above the sphaleron barrier and, using a stochastic search procedure, we…
Based on the new valley equation, we propose the most plausible method for constructing instanton-like configurations in the theory where the presence of a mass scale prevents the existence of the classical solution with a finite radius. We…
We present the anomalous cross section for baryon number violation in the standard model from the perturbation of large-order behavior of forward scattering amplitudes to the order $\left(\epsilon /n\right)^{8/3} \ln\left(\epsilon…
We consider winding number transitions in the two dimensional O(3) non-linear sigma model, modified by a suitable conformal symmetry breaking term. We discuss the general properties of the relevant instanton solutions which dominate the…
Electroweak instantons are a prediction of the Standard Model and have been studied in great detail in the past although they have not been observed. Earlier calculations of the instanton production cross section at colliders revealed that…
We present a semiclassical study of the suppression of topology changing, baryon number violating transitions induced by particle collisions in the electroweak theory. We find that below the sphaleron energy the suppression exponent is…
We make use of a semiclassical method for calculating the suppression exponent for topology changing transitions in high-energy electroweak collisions. In the Standard Model these processes are accompanied by violation of baryon and lepton…
Baryon number is an accidental symmetry of the Standard Model at the Lagrangian level. Its violation is arguably one of the most compelling phenomena predicted by physics beyond the Standard Model. Furthermore, there is a large experimental…
We report the "state of the art" of the problem of $B+L$ violation in high-energy electroweak scatterings. Results of various analyses point toward (though do not prove rigorously yet) the "half-suppression", i.e., that the $B+L$ violating…