1,542,620 research outputs found
Thermal -Brane Boundary States from Green-Schwarz Superstrings
In this paper we thermalize the type II superstrings in the GS formulation by
applying the TFD formalism. The thermal boundary conditions on the thermal
Hilbert space are obtained from the BPS -brane boundary conditions at zero
temperature. We show that thermal boundary states can be obtained by
thermalization from the BPS -branes at zero temperature. These new states
can be interpreted as thermal -branes. Next, we discuss the supersymmetry
breaking of the thermal string in the TFD approach. We identify the broken
supersymmetry with the -transformation while the
-transformation is preserved. Also, we compute the thermal partition
function and the entropy of the thermal string.Comment: 23 pages, LATeX fil
Some Properties of Amplitudes at Multi Boson Thresholds in Spontaneously Broken Scalar Theory
It is shown that in a theory of one real scalar field with
spontaneous breaking of symmetry a calculation of the amplitudes of production
by a virtual field of on-mass-shell bosons all being exactly at rest
is equivalent in any order of the loop expansion to a Euclidean space
calculation of the mean field of a kink-type configuration. Using this
equivalence it is found that all the amplitudes have no absorptive
part at the thresholds to any order of perturbation theory. This implies
non-trivial relations between multi-boson threshold production amplitudes. In
particular the on-mass-shell amplitude of the process should vanish
at the threshold in all loops. It is also shown that the factor in the amplitudes at the threshold is not eliminated by loop effects.Comment: 11 pages including 3 figures, LaTeX, TPI-MINN-92/61-
Gaps between zeros of the Riemann zeta-function
We prove that there exist infinitely many consecutive zeros of the Riemann
zeta-function on the critical line whose gaps are greater than times the
average spacing. Using a modification of our method, we also show that there
are even larger gaps between the multiple zeros of the zeta function on the
critical line (if such zeros exist)
Central values of derivatives of Dirichlet L-functions
Let C(q,+) be the set of even, primitive Dirichlet characters (mod q). Using
the mollifier method we show that L^{(k)}(1/2,chi) is not equal to zero for
almost all the characters chi in C(q,+) when k and q are large. Here,
L^{(k)}(s,chi) is the k-th derivative of of the Dirichlet L-function L(s,chi).Comment: submitted for publicatio
Measuring entanglement in condensed matter systems
We show how entanglement may be quantified in spin and cold atom many-body
systems using standard experimental techniques only. The scheme requires no
assumptions on the state in the laboratory and a lower bound to the
entanglement can be read off directly from the scattering cross section of
Neutrons deflected from solid state samples or the time-of-flight distribution
of cold atoms in optical lattices, respectively. This removes a major obstacle
which so far has prevented the direct and quantitative experimental study of
genuine quantum correlations in many-body systems: The need for a full
characterization of the state to quantify the entanglement contained in it.
Instead, the scheme presented here relies solely on global measurements that
are routinely performed and is versatile enough to accommodate systems and
measurements different from the ones we exemplify in this work.Comment: 6 pages, 2 figure
Isospin Symmetry Breaking within the HLS Model: A Full () Mixing Scheme
We study the way isospin symmetry violation can be generated within the
Hidden Local Symmetry (HLS) Model. We show that isospin symmetry breaking
effects on pseudoscalar mesons naturally induces correspondingly effects within
the physics of vector mesons, through kaon loops. In this way, one recovers all
features traditionally expected from \rho-\omg mixing and one finds support
for the Orsay phase modelling of the e^+e^- \ra \pi^+ \pi^- amplitude. We
then examine an effective procedure which generates mixing in the whole ,
\omg, sector of the HLS Model. The corresponding model allows us to
account for all two body decays of light mesons accessible to the HLS model in
modulus and phase, leaving aside the \rho \ra \pi \pi and K^* \ra K \pi
modes only, which raise a specific problem. Comparison with experimental data
is performed and covers modulus and phase information; this represents 26
physics quantities successfully described with very good fit quality within a
constrained model which accounts for SU(3) breaking, nonet symmetry breaking in
the pseudoscalar sector and, now, isospin symmetry breaking.Comment: 38 pages, version published in Eur. Phys. J.
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