2,591 research outputs found
Hadronic Decays of Excited Heavy Mesons
We studied the hadronic decays of excited states of heavy mesons (D, D_s, B
and B_s) to lighter states by emission of pi, eta or K. Wavefunctions and
energy levels of these excited states are determined using a Dirac equation for
the light quark in the potential generated by the heavy quark (including first
order corrections in the heavy quark expansion). Transition amplitudes are
computed in the context of the Heavy Chiral Quark Model.Comment: 4 pages (incl. figures), proceedings of the IV International
Conference on "Hyperons, Charm and Beauty Hadrons", Valencia (Spain
Bloom-Gilman duality of the nucleon structure function and the elastic peak contribution
The occurrence of the Bloom-Gilman duality in the nucleon structure function
is investigated by analyzing the Q**2-behavior of low-order moments, both
including and excluding the contribution arising from the nucleon elastic peak.
The Natchmann definition of the moments has been adopted in order to cancel out
target-mass effects. It is shown that the onset of the Bloom-Gilman duality
occurs around Q**2 ~ 2 (GeV/c)**2 if only the inelastic part of the nucleon
structure function is considered, whereas the inclusion of the nucleon elastic
peak contribution leads to remarkable violations of the Bloom-Gilman duality.Comment: in Proc. of the XVI European Conference on Few-body Problems in
Physics, Autrans (France), July 199
Z_3 Strings and their Interactions
We construct Z_3 vortex solutions in a model in which SU(3) is spontaneously
broken to Z_3. The model is truncated to one in which there are only two
dimensionless free parameters and the interaction of vortices within this
restricted set of models is studied numerically. We find that there is a curve
in the two dimensional space of parameters for which the energy of two
asymptotically separated vortices equals the energy of the vortices at
vanishing separation. This suggests that the inter-vortex potential for Z_3
strings might be flat for these couplings, much like the case of U(1) strings
in the Bogomolnyi limit. However, we argue that the intervortex potential is
attractive at short distances and repulsive at large separations leading to the
possibility of unstable bound states of Z_3 vortices.Comment: 8 pages; mainly corrected typos in table
Collective Quartics from Simple Groups
This article classifies Little Higgs models that have collective quartic
couplings. There are two classes of collective quartics: Special Cosets and
Special Quartics. After taking into account dangerous singlets, the smallest
Special Coset models are SU(5)/SO(5) and SU(6)/Sp(6). The smallest Special
Quartic model is SU(5)/SU(3) x SU(2) x U(1) and has not previously been
considered as a candidate Little Higgs model.Comment: 22 pages, 2 figure
Why Matrix theory works for oddly shaped membranes
We give a simple proof of why there is a Matrix theory approximation for a
membrane shaped like an arbitrary Riemann surface. As corollaries, we show that
noncompact membranes cannot be approximated by matrices and that the Poisson
algebra on any compact phase space is U(infinity). The matrix approximation
does not appear to work properly in theories such as IIB string theory or
bosonic membrane theory where there is no conserved 3-form charge to which the
membranes couple.Comment: 8 pages, 4 figures, revtex; references adde
The Isgur-Wise Function to from Sum Rules in the Heavy Quark Effective Theory
Radiative corrections to both perturbative and non-perturbative contributions
are added to existing calculations of the Isgur-Wise function . To
this end, we develop a method for calculating two-loop integrals in the heavy
quark effective theory involving two different scales. The inclusion of
terms causes to decrease as compared to the lowest
order result and shows the importance of quantum effects. The slope parameter
violates the bound given by de Rafael and Taron.Comment: 11 pages, 2 figures (not included), (LaTeX), HD-THEP-92-4
Dynamical solution to the problem at TeV scale
We introduce a new confining force (\mu-color) at TeV scale to dynamically
generate a supersymmetry preserving mass scale which would replace the \mu
parameter in the minimal supersymmetric standard model (MSSM). We discuss the
Higgs phenomenology and also the pattern of soft supersymmetry breaking
parameters allowing the correct electroweak symmetry breaking within the
\mu-color model, which have quite distinctive features from the MSSM and also
from other generalizations of the MSSM.Comment: 12 pages, REVte
Chiral Dynamics and Heavy Quark Symmetry in a Toy Field Theoretic Model
We study a solvable QCD--like toy theory, a generalization of the
Nambu--Jona-Lasinio model, which implements chiral symmetries of light quarks
and heavy quark symmetry. The chiral symmetric and chiral broken phases can be
dynamically tuned. This implies a parity doubled heavy--light meson system,
corresponding to a multiplet and a heavy spin
multiplet. Consequently the mass difference of the two multiplets is given by a
Goldberger--Treiman relation and is found to be small. The Isgur--Wise
function, , the decay constant, , and other observables are
studied.Comment: 42 pages, SSCL-PP-243; Fermi-Pub-93/059-
The anomalous threshold, confinement, and an essential singularity in the heavy-light form factor
The analytic behavior of the heavy-light meson form factor is investigated
using several relativistic examples including unconfined, weakly confined, and
strongly confined mesons. It is observed that confinement erases the anomalous
threshold singularity and also induces an essential singularity at the normal
annihilation threshold. In the weak confinement limit, the "would be" anomalous
threshold contribution is identical to that of the real singularity on its
space-like side.Comment: Latex 2.09 with epsf.sty. 24 pages of text and 8 postscript figures.
Postscript version of complete paper will also be available soon at
http://phenom.physics.wisc.edu/pub/preprints/1997/madph-97-983 or at
ftp://phenom.physics.wisc.edu/pub/preprints/1997/madph-97-98
High Density Effective Theory Confronts the Fermi Liquid
The high density effective theory recently introduced by Hong and Hsu to
describe ultradense relativistic fermionic matter is used to calculate the
tree-level forward scattering amplitude between two particles at the Fermi
surface. While the direct term correctly reproduces that of the underlying
gauge theory, the exchange term has the wrong sign. The physical consequences
are discussed in the context of Landau's theoretical description of the Fermi
liquid.Comment: 15 pages, 2 figures; conclusion expanded, reference adde
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