47,184 research outputs found
Dynamics of quantum spin chains and multi-fermion excitation continua
We use the Jordan-Wigner representation to study dynamic quantities for the
spin-1/2 XX chain in a transverse magnetic field. We discuss in some detail the
properties of the four-fermion excitation continuum which is probed by the
dynamic trimer structure factor.Comment: Presented at the SCES '05 - The International Conference on Strongly
Correlated Electron Systems (Vienna, July 26-30, 2005
Factorization in hard diffraction
In this talk, I reviewed the role of factorization in diffraction hard
scattering.Comment: Talk presented at the Ringberg Workshop on ``New Trends in HERA
Physics 2001''. 10 pages, 6 postscript figures. Misprints correcte
Improving LLR Tests of Gravitational Theory
Accurate analysis of precision ranges to the Moon has provided several tests
of gravitational theory including the Equivalence Principle, geodetic
precession, parameterized post-Newtonian (PPN) parameters and ,
and the constancy of the gravitational constant {\it G}. Since the beginning of
the experiment in 1969, the uncertainties of these tests have decreased
considerably as data accuracies have improved and data time span has
lengthened. We are exploring the modeling improvements necessary to proceed
from cm to mm range accuracies enabled by the new Apache Point Observatory
Lunar Laser-ranging Operation (APOLLO) currently under development in New
Mexico. This facility will be able to make a significant contribution to the
solar system tests of fundamental and gravitational physics. In particular, the
Weak and Strong Equivalence Principle tests would have a sensitivity
approaching 10, yielding sensitivity for the SEP violation parameter
of , general relativistic effects would
be tested to better than 0.1%, and measurements of the relative change in the
gravitational constant, , would be % the inverse age of the
universe. Having this expected accuracy in mind, we discusses the current
techniques, methods and existing physical models used to process the LLR data.
We also identify the challenges for modeling and data analysis that the LLR
community faces today in order to take full advantage of the new APOLLO ranging
station.Comment: 15 pages, 3 figures, talk presented at 2003 NASA/JPL Workshop on
Fundamental Physics in Space, April 14-16, 2003, Oxnard, C
Microscopic laser-driven high-energy colliders
The concept of a laser-guided collider in the high-energy regime is
presented and its feasibility discussed. Ultra-intense laser pulses and strong
static magnetic fields are employed to unite in one stage the electron and
positron acceleration and their head-on-head collision. We show that the
resulting coherent collisions in the GeV regime yield an enormous enhancement
of the luminosity with regard to conventional incoherent colliders
COMPLETE SOLUTION OF THE XXZ-MODEL ON FINITE RINGS. DYNAMICAL STRUCTURE FACTORS AT ZERO TEMPERATURE.
The finite size effects of the dynamical structure factors in the XXZ-model
are studied in the euclidean time -representation. Away from the
critical momentum finite size effects turn out to be small except for
the large limit. The large finite size effects at the critical momentum
signal the emergence of infrared singularities in the spectral
-representation of the dynamical structure factors.Comment: PostScript file with 12 pages + 11 figures uuencoded compresse
Repeated injection of atrial natriuretic peptide (a-hANP) in normal man: cardiovascular and renal actions
Process studies in the hydro- and geosphere of the tropical/subtropical North Atlantic Cruise No. 04 December 03, – April 03, 2006/2007, Fort de France (Martinique) – Las Palmas (Spain)
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