759 research outputs found
Deuteron tensor polarization component T_20(Q^2) as a crucial test for deuteron wave functions
The deuteron tensor polarization component T_20(Q^2) is calculated by
relativistic Hamiltonian dynamics approach. It is shown that in the range of
momentum transfers available in to-day experiments, relativistic effects, meson
exchange currents and the choice of nucleon electromagnetic form factors almost
do not influence the value of T_20(Q^2). At the same time, this value depends
strongly on the actual form of the deuteron wave function, that is on the model
of NN-interaction in deuteron. So the existing data for T_20(Q^2) provide a
crucial test for deuteron wave functions.Comment: 11 pages, 3 figure
The Singularity in Generic Gravitational Collapse Is Spacelike, Local, and Oscillatory
A longstanding conjecture by Belinskii, Khalatnikov, and Lifshitz that the
singularity in generic gravitational collapse is spacelike, local, and
oscillatory is explored analytically and numerically in spatially inhomogeneous
cosmological spacetimes. With a convenient choice of variables, it can be seen
analytically how nonlinear terms in Einstein's equations control the approach
to the singularity and cause oscillatory behavior. The analytic picture
requires the drastic assumption that each spatial point evolves toward the
singularity as an independent spatially homogeneous universe. In every case,
detailed numerical simulations of the full Einstein evolution equations support
this assumption.Comment: 7 pages includes 4 figures. Uses Revtex and psfig. Received
"honorable mention" in 1998 Gravity Research Foundation essay contest.
Submitted to Mod. Phys. Lett.
Boundary bound states and boundary bootstrap in the sine-Gordon model with Dirichlet boundary conditions.
We present a complete study of boundary bound states and related boundary
S-matrices for the sine-Gordon model with Dirichlet boundary conditions. Our
approach is based partly on the bootstrap procedure, and partly on the explicit
solution of the inhomogeneous XXZ model with boundary magnetic field and of the
boundary Thirring model. We identify boundary bound states with new ``boundary
strings'' in the Bethe ansatz. The boundary energy is also computed.Comment: 25 pages, harvmac macros Report USC-95-001
The gl(M|N) Super Yangian and Its Finite Dimensional Representations
Methods are developed for systematically constructing the finite dimensional
irreducible representations of the super Yangian Y(gl(M|N)) associated with the
Lie superalgebra gl(M|N). It is also shown that every finite dimensional
irreducible representation of Y(gl(M|N)) is of highest weight type, and is
uniquely characterized by a highest weight. The necessary and sufficient
conditions for an irrep to be finite dimensional are given.Comment: 14 pages plain late
A note on quantization operators on Nichols algebra model for Schubert calculus on Weyl groups
We give a description of the (small) quantum cohomology ring of the flag
variety as a certain commutative subalgebra in the tensor product of the
Nichols algebras. Our main result can be considered as a quantum analog of a
result by Y. Bazlov
Non-critical string pentagon equations and their solutions
We derive pentagon type relations for the 3-point boundary tachyon
correlation functions in the non-critical open string theory with generic
c_{matter} < 1 and study their solutions in the case of FZZ branes. A new
general formula for the Liouville 3-point factor is derived.Comment: 18 pages, harvmac; misprints corrected, section 3.2 extended, a new
general formula for the Liouville 3-point factor adde
Ground state and low excitations of an integrable chain with alternating spins
An anisotropic integrable spin chain, consisting of spins and
, is investigated \cite{devega}. It is characterized by two real
parameters and , the coupling constants of the spin
interactions. For the case and the ground state
configuration is obtained by means of thermodynamic Bethe ansatz. Furthermore
the low excitations are calculated. It turns out, that apart from free magnon
states being the holes in the ground state rapidity distribution, there exist
bound states given by special string solutions of Bethe ansatz equations (BAE)
in analogy to \cite{babelon}. The dispersion law of these excitations is
calculated numerically.Comment: 16 pages, LaTeX, uses ioplppt.sty and PicTeX macro
Oscillatory regime in the Multidimensional Homogeneous Cosmological Models Induced by a Vector Field
We show that in multidimensional gravity vector fields completely determine
the structure and properties of singularity. It turns out that in the presence
of a vector field the oscillatory regime exists in all spatial dimensions and
for all homogeneous models. By analyzing the Hamiltonian equations we derive
the Poincar\'e return map associated to the Kasner indexes and fix the rules
according to which the Kasner vectors rotate. In correspondence to a
4-dimensional space time, the oscillatory regime here constructed overlap the
usual Belinski-Khalatnikov-Liftshitz one.Comment: 9 pages, published on Classical and Quantum Gravit
Spike Oscillations
According to Belinskii, Khalatnikov and Lifshitz (BKL), a generic spacelike
singularity is characterized by asymptotic locality: Asymptotically, toward the
singularity, each spatial point evolves independently from its neighbors, in an
oscillatory manner that is represented by a sequence of Bianchi type I and II
vacuum models. Recent investigations support a modified conjecture: The
formation of spatial structures (`spikes') breaks asymptotic locality. The
complete description of a generic spacelike singularity involves spike
oscillations, which are described by sequences of Bianchi type I and certain
inhomogeneous vacuum models. In this paper we describe how BKL and spike
oscillations arise from concatenations of exact solutions in a
Hubble-normalized state space setting, suggesting the existence of hidden
symmetries and showing that the results of BKL are part of a greater picture.Comment: 38 pages, 14 figure
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