958 research outputs found
Brane world generation by matter and gravity
We present a non-compact (4 + 1) dimensional model with a local strong
four-fermion interaction supplementing it with gravity. In the strong coupling
regime it reveals the spontaneous translational symmetry breaking which
eventually leads to the formation of domain walls, or thick 3-branes, embedded
in the AdS-5 manifold. To describe this phenomenon we construct the appropriate
low-energy effective Action and find kink-like vacuum solutions in the
quasi-flat Riemannian metric. We discuss the generation of ultra-low-energy (3
+ 1) dimensional physics and we establish the relation among the bulk five
dimensional gravitational constant, the brane Newton's constants and the
curvature of AdS-5 space-time. The plausible relation between the compositeness
scale of the scalar matter and the symmetry breaking scale is shown to support
the essential decoupling of branons, the scalar fluctuations of the brane, from
the Standard Model matter, supporting their possible role in the dark matter
saturation. The induced cosmological constant on the brane does vanish due to
exact cancellation of matter and gravity contributions.Comment: 35 pages, JHEP3 style, refs.adde
New Two-Dimensional Quantum Models Partially Solvable by Supersymmetrical Approach
New solutions for second-order intertwining relations in two-dimensional SUSY
QM are found via the repeated use of the first order supersymmetrical
transformations with intermediate constant unitary rotation. Potentials
obtained by this method - two-dimensional generalized P\"oschl-Teller
potentials - appear to be shape-invariant. The recently proposed method of
separation of variables is implemented to obtain a part of their
spectra, including the ground state. Explicit expressions for energy
eigenvalues and corresponding normalizable eigenfunctions are given in analytic
form. Intertwining relations of higher orders are discussed.Comment: 21 pages. Some typos corrected; imrovements added in Subsect.4.2;
some references adde
A New Class of PT-symmetric Hamiltonians with Real Spectra
We investigate complex PT-symmetric potentials, associated with quasi-exactly
solvable non-hermitian models involving polynomials and a class of rational
functions. We also look for special solutions of intertwining relations of SUSY
Quantum Mechanics providing a partnership between a real and a complex
PT-symmetric potential of the kind mentioned above. We investigate conditions
sufficient to ensure the reality of the full spectrum or, for the quasi-exactly
solvable systems, the reality of the energy of the finite number of levels.Comment: 9 pages, Late
Local realizations of -Oscillators in Quantum Mechanics
Representations of the quantum q-oscillator algebra are studied with
particular attention to local Hamiltonian representations of the Schroedinger
type. In contrast to the standard harmonic oscillators such systems exhibit a
continuous spectrum. The general scheme of realization of the q-oscillator
algebra on the space of wave functions for a one-dimensional Schroedinger
Hamiltonian shows the existence of non-Fock irreducible representations
associated to the continuous part of the spectrum and directly related to the
deformation. An algorithm for the mapping of energy levels is described.Comment: 12 pages, LaTeX, Phys. Lett. A, to be publishe
Symmetries and the cosmological constant puzzle
We outline the evaluation of the cosmological constant in the framework of
the standard field-theoretical treatment of vacuum energy and discuss the
relation between the vacuum energy problem and the gauge-group spontaneous
symmetry breaking. We suggest possible extensions of the 't Hooft-Nobbenhuis
symmetry, in particular, its complexification till duality symmetry and discuss
the compatible implementation on gravity. We propose to use the discrete
time-reflection transform to formulate a framework in which one can eliminate
the huge contributions of vacuum energy into the effective cosmological
constant and suggest that the breaking of time--reflection symmetry could be
responsible for a small observable value of this constant.Comment: 11 pages, more relevant refs, refining cutoff definition of
cosmological constant + eq.for regularized pressure adde
Dimensional structural constants from chiral and conformal bosonization of QCD
We derive the dimensional non-perturbative part of the QCD effective action
for scalar and pseudoscalar meson fields by means of chiral and conformal
bosonization. The related structural coupling constants L_5 and L_8 of the
chiral lagrangian are estimated using general relations which are valid in a
variety of chiral bosonization models without explicit reference to model
parameters. The asymptotics for large scalar fields in QCD is elaborated, and
model-independent constraints on dimensional coupling constants of the
effective meson lagrangian are evaluated. We determine also the interaction
between scalar quarkonium and the gluon density and obtain the scalar
glueball-quarkonium potential.Comment: 21 pages, LaTe
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