35 research outputs found
Probing coherent charmonium photoproduction off light nuclei at medium energies
We demonstrate how the elementary amplitudes , the
amplitude of the nondiagonal transition, and
the total and cross sections can be determined from
measurements of the coherent and photoproduction off light
nuclei at moderate energies. For this purpose we provide a detailed numerical
analysis of the coherent charmonium photoproduction off silicon within the
generalized vector dominance model (GVDM) adjusted to account for the physics
of charmonium models and color transparency phenomenon.Comment: 8 pages, 5 figures (color
Two-loop two-point functions with masses: asymptotic expansions and Taylor series, in any dimension
In all mass cases needed for quark and gluon self-energies, the two-loop
master diagram is expanded at large and small , in dimensions, using
identities derived from integration by parts. Expansions are given, in terms of
hypergeometric series, for all gluon diagrams and for all but one of the quark
diagrams; expansions of the latter are obtained from differential equations.
Pad\'{e} approximants to truncations of the expansions are shown to be of great
utility. As an application, we obtain the two-loop photon self-energy, for all
, and achieve highly accelerated convergence of its expansions in powers of
or , for .Comment: 25 pages, OUT--4102--43, BI--TP/92--5
Possible retardation effects of quark confinement on the meson spectrum
The reduced Bethe-Salpeter equation with scalar confinement and vector gluon
exchange is applied to quark-antiquark bound states. The so called intrinsic
flaw of Salpeter equation with static scalar confinement is investigated. The
notorious problem of narrow level spacings is found to be remedied by taking
into consideration the retardation effect of scalar confinement. Good fit for
the mass spectrum of both heavy and light quarkomium states is then obtained.Comment: 14 pages in LaTex for
Large Possible retardation effects of quark confinement on the meson spectrum II
We present the results of a study of heavy-light-quark bound states in the
context of the reduced Bethe-Salpeter equation with relativistic vector and
scalar interactions. We find that satisfactory fits may also be obtained when
the retarded effect of the quark-antiquark interaction is concerned.Comment: 11 pages, RevTex, to appear in PR
Hamiltonian Quantization of Effective Lagrangians with Massive Vector Fields
Effective Lagrangians containing arbitrary interactions of massive vector
fields are quantized within the Hamiltonian path integral formalism. It is
proven that correct Hamiltonian quantization of these models yields the same
result as naive Lagrangian quantization (Matthews's theorem). This theorem
holds for models without gauge freedom as well as for (linearly or nonlinearly
realized) spontaneously broken gauge theories. The Stueckelberg formalism, a
procedure to rewrite effective Lagrangians in a gauge invariant way, is
reformulated within the Hamiltonian formalism as a transition from a second
class constrained theory to an equivalent first class constrained theory. The
relations between linearly and nonlinearly realized spontaneously broken gauge
theories are discussed. The quartically divergent Higgs self interaction is
derived from the Hamiltonian path integral.Comment: 16 pages LaTeX, BI-TP 93/1
Equivalence of Hamiltonian and Lagrangian Path Integral Quantization: Effective Gauge Theories
The equivalence of correct Hamiltonian and naive Lagrangian (Faddeev--Popov)
path integral quantization (Matthews's theorem) is proven for gauge theories
with arbitrary effective interaction terms. Effective gauge-boson
self-interactions and effective interactions with scalar and fermion fields are
considered. This result becomes extended to effective gauge theories with
higher derivatives of the fields.Comment: 14 pages LaTeX, BI-TP 93/40, August 199
Heterotic / type I duality and D-brane instantons
We study heterotic/type I duality in d=8,9 uncompactified dimensions. We
consider the special (``BPS saturated'') F^4 and R^4 terms in the effective
one-loop heterotic action, which are expected to be non-perturbatively exact.
Under the standard duality map these translate to tree-level, perturbative and
non-perturbative contributions on the type I side. We check agreement with the
one-loop open string calculation, and discuss the higher-order perturbative
contributions, which arise because of the mild non-holomorphicities of the
heterotic elliptic genus. We put the heterotic world-sheet instanton
corrections in a form that can be motivated as arising from a D-brane instanton
calculation on the type-I side.Comment: latex 23 pages, 3 figures eps included. Final version to appear in
Nuclear Physics
Semileptonic Meson Decays in the Quark Model: An Update
We present the predictions of ISGW2, an update of the ISGW quark model for
semileptonic meson decays. The updated model incorporates a number of features
which should make it more reliable, including the constraints imposed by Heavy
Quark Symmetry, hyperfine distortions of wavefunctions, and form factors with
more realistic high recoil behaviors.Comment: All text and tables contained in the ".latex" file and all figures
(14) contained in the ".uu" file