6,388 research outputs found
Factorization of the finite temperature correlation functions of the XXZ chain in a magnetic field
We present a conjecture for the density matrix of a finite segment of the XXZ
chain coupled to a heat bath and to a constant longitudinal magnetic field. It
states that the inhomogeneous density matrix, conceived as a map which
associates with every local operator its thermal expectation value, can be
written as the trace of the exponential of an operator constructed from
weighted traces of the elements of certain monodromy matrices related to and only two transcendental functions pertaining to
the one-point function and the neighbour correlators, respectively. Our
conjecture implies that all static correlation functions of the XXZ chain are
polynomials in these two functions and their derivatives with coefficients of
purely algebraic origin.Comment: 35 page
Modified Tetrahedron Equations and Related 3D Integrable Models
Using a modified version of the tetrahedron equations we construct a new
family of -state three-dimensional integrable models with commuting
two-layer transfer-matrices. We investigate a particular class of solutions to
these equations and parameterize them in terms of elliptic functions. The
corresponding models contain one free parameter -- an elliptic modulus.Comment: 26 pages, LaTeX fil
Asymptotic Behavior of the Emptiness Formation Probability in the Critical Phase of XXZ Spin Chain
We study the Emptiness Formation Probability (EFP) for the spin 1/2 XXZ spin
chain. EFP P(n) detects a formation of ferromagnetic string of the length n in
the ground state. It is expected that EFP decays in a Gaussian way for large
strings P(n) ~ n^{-gamma} C^{-n^2}. Here, we propose the explicit expressions
for the rate of Gaussian decay C as well as for the exponent gamma. In order to
confirm the validity of our formulas, we employed an ab initio simulation
technique of the density-matrix renormalization group to simulate XXZ spin
chain of sufficient length. Furthermore, we performed Monte-Carlo integration
of the Jimbo-Miwa multiple integral for P(n). Those numerical results for P(n)
support our formulas fairly definitely.Comment: 9 pages, 2 figure
Single top quarks at the Fermilab Tevatron
We present a calculation of the single top quark cross section for
proton-antiproton interactions with sqrt(s) = 1.8 TeV at the Fermilab Tevatron
collider. We examine the effects of top mass, parton distribution functions,
QCD scale, and collision energy, on each of the component production
mechanisms, and study the kinematic distributions for standard model
electroweak production. At the upgraded Tevatron with sqrt(s) = 2.0 TeV and
high luminosity, it will be possible to test the nature of the Wtb coupling
using single top production. We estimate the sensitivity to measure the single
top cross section, and thus to directly measure V_tb and the top quark partial
width. We show what happens to the V_tb measurement when an anomalous (V+A)
component is added to the Wtb coupling, and how the top quark polarization
affects the kinematic distributions.Comment: 31 pages including 11 figure
Hidden Grassmann Structure in the XXZ Model IV: CFT limit
The Grassmann structure of the critical XXZ spin chain is studied in the
limit to conformal field theory. A new description of Virasoro Verma modules is
proposed in terms of Zamolodchikov's integrals of motion and two families of
fermionic creation operators. The exact relation to the usual Virasoro
description is found up to level 6.Comment: 44 pages, 1 figure. Version 3: some corrections are don
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