相关论文: Small-Recoil Approximation
The adiabatic approximation has formed the basis for much of our understandings of the interaction of light and electrons. The classical non-recoil approximation or quantum mechanical Wolkow states of free electron waves have been routinely…
We study theoretically the phase diagram of strongly coupled two-dimensional Bose-Fermi mixtures interacting with attractive short-range potentials as a function of the particle densities. We focus on the limit where the size of the bound…
In a one-dimensional weakly interacting Bose-Fermi mixture one branch of elementary excitations is well described by the Bogoliubov spectrum. Here we use the microscopic theory to study the decay of such quasiparticle excitations. The main…
Diagrammatic techniques are well-known in the calculation of dispersion interactions between atoms or molecules. The multipolar coupling scheme combined with Feynman ordered diagrams significantly reduces the number of graphs compared to…
We demonstrate clear collective atomic recoil motion in a dilute, momentum-squeezed, ultra-cold degenerate fermion gas by circumventing the effects of Pauli blocking. Although gain from bosonic stimulation is necessarily absent because the…
Nonlinear optical responses are a crucial probe of physical systems including periodic solids. In the absence of electron-electron interactions, they are calculable with standard perturbation theory starting from the band structure of Bloch…
A two-dimensional lattice system of non-interacting electrons in a homogeneous magnetic field with half a flux quantum per plaquette and a random potential is considered. For the large scale behavior a supersymmetric theory with collective…
Theory of the spectrum of localized two-level quasi-particle renormalized due to interaction with polarization phonons at cryogenic temperature is developed using the generalized method of Feynman-Pines diagram technique. Using the…
The goal of this paper is to sum over a class of enhanced diagrams, and derive a new Pomeron Green function. It is found that this sum gives the Pomeron contribution to the scattering amplitude that decreases with energy. In other words, we…
We discuss a formula for the sum of tree diagrams of $n$-bosons scattering from a heavy fermion. This formula can be considered as a generalization of the eikonal formula to include non-abelian vertices. It will be used to demonstrate the…
Cold atom experiments show that a mobile impurity particle immersed in a Bose-Einstein condensate forms a well-defined quasiparticle (Bose polaron) for weak to moderate impurity-boson interaction strengths, whereas a significant line…
The paper considers quantum electrodynamics (QED) and weak interaction of elementary particles in the lower orders of the perturbation theory using nonlocal Hamiltonian in the Foldy-Wouthuysen (FW) representation. Feynman rules in the FW…
A method of calculating Feynman diagrams from their small momentum expansion [1] is extended to diagrams with zero mass thresholds. We start from the asymptotic expansion in large masses [2] (applied to the case when all $M_i^2$ are large…
In this paper we argue that in the kinematic range given by $ 1 \ll \ln(1/\as^2) \ll \as Y \ll \frac{1}{\as}$, we can reduce the Pomeron calculus to the exchange of non-interacting Pomerons with the renormalized amplitude of their…
In this thesis we present an introduction to Soft-Collinear Effective Theory, which can be used to prove (or disprove) factorization theorems to all orders in the strong coupling constant for some B decays into light and energetic…
We develop a functional integral formalism for ultracold gases of fermionic atoms. It describes the BEC - BCS crossover and involves both atom and molecule fields. Beyond mean field theory we include the fluctuations of the molecule field…
We present a method using Feynman-like diagrams to calculate the statistical properties of random many-body potentials. This method provides a promising alternative to existing techniques typically applied to this class of problems, such as…
The eikonal approximation is at the heart of many theoretical and phenomenological studies involving multiple soft gauge boson emissions in high energy physics. We describe our efforts towards the extension of the eikonal approximation for…
Using the Feynman-Pines diagram technique, the energy spectrum of localized quasi-particles interacting with polarization phonons is calculated and analyzed in the wide range of energies at the finite temperature of the system. It is…
By describing strong interactions between hadrons via a relativistic supermultiplet scheme and regarding weak interactions as a perturbation thereof, we derive expressions for nonleptonic weak decay amplitudes in terms of constituent quark…