9,077 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
Hidden Grassmann structure in the XXZ model V: sine-Gordon model
We study one-point functions of the sine-Gordon model on a cylinder. Our
approach is based on a fermionic description of the space of descendent fields,
developed in our previous works for conformal field theory and the sine-Gordon
model on the plane. In the present paper we make an essential addition by
giving a connection between various primary fields in terms of yet another kind
of fermions. The one-point functions of primary fields and descendants are
expressed in terms of a single function defined via the data from the
thermodynamic Bethe Ansatz equations.Comment: 36 pages. Some corrections are done in latest version, especially in
the subsection 10.
Exact evaluation of density matrix elements for the Heisenberg chain
We have obtained all the density matrix elements on six lattice sites for the
spin-1/2 Heisenberg chain via the algebraic method based on the quantum
Knizhnik-Zamolodchikov equations. Several interesting correlation functions,
such as chiral correlation functions, dimer-dimer correlation functions, etc...
have been analytically evaluated. Furthermore we have calculated all the
eigenvalues of the density matrix and analyze the eigenvalue-distribution. As a
result the exact von Neumann entropy for the reduced density matrix on six
lattice sites has been obtained.Comment: 33 pages, 4 eps figures, 3 author
Measuring the Higgs Branching Fraction into two Photons at Future Linear \ee Colliders
We examine the prospects for measuring the \gaga branching fraction of a
Standard Model-like Higgs boson with a mass of 120 GeV at the future TESLA
linear \ee collider, assuming an integrated luminosity of 1 ab and
center-of-mass energies of 350 GeV and 500 GeV. The Higgs boson is produced in
association with a fermion pair via the Higgsstrahlung process \ee ,
with \qq or \nn, or the WW fusion reaction . A relative uncertainty on BF(\hgg) of~16% can be achieved in
unpolarized \ee collisions at =~500 GeV, while for =~350
GeV the expected precision is slightly poorer. With appropriate initial state
polarizations BF(\hgg)/BF(\hgg) can be improved to 10%. If this
measurement is combined with the expected error for the total Higgs width, a
precision of 10% on the \gaga Higgs boson partial width appears feasible.Comment: 14 pages, 5 figure
Branching Fraction Measurements of the SM Higgs with a Mass of 160 GeV at Future Linear \ee Colliders
Assuming an integrated luminosity of 500 fb and a center-of-mass
energy of 350 GeV, we examine the prospects for measuring branching fractions
of a Standard Model-like Higgs boson with a mass of 160 GeV at the future
linear \ee collider TESLA when the Higgs is produced via the Higgsstrahlung
mechanism, \ee \pfr HZ. We study in detail the precisions achievable for the
branching fractions of the Higgs into WW, ZZ and \bb. However, the
measurement of BF(H \pfr \gaga) remains a great challence. Combined with the
expected error for the inclusive Higgsstrahlung production rate the uncertainty
for the total width of the Higgs is estimated.Comment: 17 pages Latex, including 7 figure
Characteristics of campers who used various types of shelter equipment at Chicot State Park in Louisiana
The primary objective of this study was to identify the needs and desires of campers who use various types of shelter equipment. Identifying and evaluating camper tastes and preferences provide outdoor recreation planners with the knowledge needed for designing campgrounds which fit the needs of the campers. Campers were classified into four categories, based on the type of shelter equipment that they use: I. Campers who use travel trailers or motor homes over 23 feet in length. II. Campers who use either travel trailers or motor homes less than 23 feet in length, or pickup truck campers or vans with plumbing facilities (shower, toilet, sink). III. Campers who use either pickup truck campers or vans without plumbing facilities, or tent trailers. IV. Campers who use tents. Data for the study were obtained from 413 personal interviews which were conducted in three campgrounds at Chicot State Park in Louisiana. Questions revealing type of equipment owned and desired, camping experience, socioeconomic characteristics, reasons for camping and characteristics of a preferred campsite were asked each respondent. Chi-square analysis, Duncan\u27s Multiple Range Statistical Test and one-way analysis of variance were used to determine which characteristics were significantly different between the camper classes. Results showed that the four classes had unique socioeconomic characteristics, suggesting that each class was different from the others, The data revealed that only three of the four classes of campers had different campsite preferences. Campers in Classes I and II generally desired the same campsite attributes. Respondents who camped on weekdays had different characteristics from those who camped on weekends. These findings suggest that campsites should not be designed to accommodate all types of campers. Three different types of campsites are desired by the four classes of campers. If it is impractical to provide three types of campsites in an area, then efforts should be made to design two types of campsites, one for tent campers and the other for nontent campers. Forcing campers to use campsites with undesirable attributes will not permit them to have maximum enjoyment from their recreational experiences
Short-distance thermal correlations in the XXZ chain
Recent studies have revealed much of the mathematical structure of the static
correlation functions of the XXZ chain. Here we use the results of those
studies in order to work out explicit examples of short-distance correlation
functions in the infinite chain. We compute two-point functions ranging over 2,
3 and 4 lattice sites as functions of the temperature and the magnetic field
for various anisotropies in the massless regime . It turns
out that the new formulae are numerically efficient and allow us to obtain the
correlations functions over the full parameter range with arbitrary precision.Comment: 25 pages, 5 colored figure
Particles and strings in a (2+1)-D integrable quantum model
We give a review of some recent work on generalization of the Bethe ansatz in
the case of -dimensional models of quantum field theory. As such a model,
we consider one associated with the tetrahedron equation, i.e. the
-dimensional generalization of the famous Yang--Baxter equation. We
construct some eigenstates of the transfer matrix of that model. There arise,
together with states composed of point-like particles analogous to those in the
usual -dimensional Bethe ansatz, new string-like states and
string-particle hybrids
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