40,554 research outputs found
Quiver Matrix Mechanics for IIB String Theory (I): Wrapping Membranes and Emergent Dimension
In this paper we present a discrete, non-perturbative formulation for type
IIB string theory. Being a supersymmetric quiver matrix mechanics model in the
framework of M(atrix) theory, it is a generalization of our previous proposal
of compactification via orbifolding for deconstructed IIA strings. In the
continuum limit, our matrix mechanics becomes a -dimensional Yang-Mills
theory with 16 supercharges. At the discrete level, we are able to construct
explicitly the solitonic states that correspond to membranes wrapping on the
compactified torus in target space. These states have a manifestly
SL(2,\integer)-invariant spectrum with correct membrane tension, and give
rise to an emergent flat dimension when the compactified torus shrinks to
vanishing size.Comment: LaTeX 2e; 39 pages, 3 eps figures. v2: typos corrected; references
added; identification of certain membrane states added. v3: minor corrections
on membrane state
Geometry effects in confined space
In this paper we calculate some exact solutions of the grand partition
functions for quantum gases in confined space, such as ideal gases in two- and
three-dimensional boxes, in tubes, in annular containers, on the lateral
surface of cylinders, and photon gases in three-dimensional boxes. Based on
these exact solutions, which, of course, contain the complete information about
the system, we discuss the geometry effect which is neglected in the
calculation with the thermodynamic limit , and analyze the
validity of the quantum statistical method which can be used to calculate the
geometry effect on ideal quantum gases confined in two-dimensional irregular
containers. We also calculate the grand partition function for phonon gases in
confined space. Finally, we discuss the geometry effects in realistic systems.Comment: Revtex,15 pages, no figur
Dynamically Spontaneous Symmetry Breaking and Masses of Lightest Nonet Scalar Mesons as Composite Higgs Bosons
Based on the (approximate) chiral symmetry of QCD Lagrangian and the bound
state assumption of effective meson fields, a nonlinearly realized effective
chiral Lagrangian for meson fields is obtained from integrating out the quark
fields by using the new finite regularization method. As the new method
preserves the symmetry principles of the original theory and meanwhile keeps
the finite quadratic term given by a physically meaningful characteristic
energy scale , it then leads to a dynamically spontaneous symmetry
breaking in the effective chiral field theory. The gap equations are obtained
as the conditions of minimal effective potential in the effective theory. The
instanton effects are included via the induced interactions discovered by 't
Hooft and found to play an important role in obtaining the physical solutions
for the gap equations. The lightest nonet scalar mesons(, ,
and ) appearing as the chiral partners of the nonet pseudoscalar mesons
are found to be composite Higgs bosons with masses below the chiral symmetry
breaking scale GeV. In particular, the mass of the
singlet scalar (or the ) is found to be MeV.Comment: 15 pages, Revtex, published version, Eur. Phys. J. C (2004) (DOI)
10.1140/epjcd/s2004-01-001-
Heat-kernel approach for scattering
An approach for solving scattering problems, based on two quantum field
theory methods, the heat kernel method and the scattering spectral method, is
constructed. This approach converts a method of calculating heat kernels into a
method of solving scattering problems. This allows us to establish a method of
scattering problems from a method of heat kernels. As an application, we
construct an approach for solving scattering problems based on the covariant
perturbation theory of heat-kernel expansions. In order to apply the
heat-kernel method to scattering problems, we first calculate the off-diagonal
heat-kernel expansion in the frame of the covariant perturbation theory.
Moreover, as an alternative application of the relation between heat kernels
and partial-wave phase shifts presented in this paper, we give an example of
how to calculate a global heat kernel from a known scattering phase shift
Do bosons obey Bose-Einstein distribution: two iterated limits of Gentile distribution
It is a common impression that by only setting the maximum occupation number
to infinity, which is the demand of the indistinguishability of bosons, one can
achieve the statistical distribution that bosons obey -- the Bose-Einstein
distribution. In this letter, however, we show that only with an infinite
maximum occupation number one cannot uniquely achieve the Bose-Einstein
distribution, since in the derivation of the Bose-Einstein distribution, the
problem of iterated limit is encountered. For achieving the Bose-Einstein
distribution, one needs to take both the maximum occupation number and the
total number of particles to infinities, and, then, the problem of the order of
taking limits arises. Different orders of the limit operations will lead to
different statistical distributions. For achieving the Bose-Einstein
distribution, besides setting the maximum occupation number, we also need to
state the order of the limit operations.Comment: 6 pages, no figur
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