1,794 research outputs found
Radiative quarkonium decays and the NMSSM Higgs interpretation of the HyperCP Sigma+ --> p mu+mu- events
We study the potential of radiative decays of the Upsilon(1S) and of the phi
mesons to search for a light pseudoscalar Higgs boson, proposed as a possible
interpretation of Sigma+ --> p mu+mu- events observed by the HyperCP
collaboration at Fermilab. We conclude that the detection of this signal should
certainly be possible with the current CLEO Upsilon(1S) data, and is within the
reach of KLOE in at least part of the range of couplings suggested by the
HyperCP findings.Comment: 6 pages, no figure
Color Non-Singlet Spectroscopy
Study of the spectrum and structure of color non-singlet combinations of
quarks and antiquarks, neutralized by a non-dynamical compensating color
source, may provide an interesting way to address questions about QCD that
cannot be addressed by experiment at the present time. These states can be
simulated in lattice QCD and the results can be used to improve
phenomenological models of hadrons. Here these ideas are applied to color
triplet states of qqqq and qq bar q.Comment: References added and typos correcte
Analysis of General Power Counting Rules in Effective Field Theory
We derive the general counting rules for a quantum effective field theory
(EFT) in dimensions. The rules are valid for strongly and weakly
coupled theories, and predict that all kinetic energy terms are canonically
normalized. They determine the energy dependence of scattering cross sections
in the range of validity of the EFT expansion. We show that the size of cross
sections is controlled by the power counting of EFT, not by chiral
counting, even for chiral perturbation theory (PT). The relation between
and is generalized to dimensions. We show that the
naive dimensional analysis counting is related to counting. The
EFT counting rules are applied to PT, low-energy weak interactions,
Standard Model EFT and the non-trivial case of Higgs EFT.Comment: V2: more details and examples added; version published in journal. 17
pages, 4 figures, 2 table
Baryon Masses in Partially Quenched Heavy Hadron Chiral Perturbation Theory
The masses of baryons containing a heavy quark are calculated to
next-to-leading order in partially quenched heavy hadron chiral perturbation
theory. Calculations are performed for three light flavors in the isospin limit
and additionally for two light non-degenerate flavors. The results presented
are necessary for extrapolating lattice QCD and partially quenched lattice QCD
calculations of the heavy hadron masses.Comment: 20 pages, 2 figures, RevTex
Break-down of the single-active-electron approximation for one-photon ionization of the B state of H exposed to intense laser fields
Ionization, excitation, and de-excitation to the ground state is studied
theoretically for the first excited singlet state B of H
exposed to intense laser fields with photon energies in between about 3 eV and
13 eV. A parallel orientation of a linear polarized laser and the molecular
axis is considered. Within the dipole and the fixed-nuclei approximations the
time-dependent Schr\"odinger equation describing the electronic motion is
solved in full dimensionality and compared to simpler models. A dramatic
break-down of the single-active-electron approximation is found and explained
to be due to the inadequate description of the final continuum states.Comment: 9 pages, 4 figure
Axial Anomaly and Transition Form Factors
We investigate the properties of the amplitude induced by the anomaly. In a
relatively high energy region those amplitudes are constructed by the vector
meson poles and the anomaly terms, in which the anomaly terms can be
essentially evaluated by the triangle quark graph. We pay our attention to the
anomaly term and make intensive analysis of the existing experimental data,
i.e., the electromagnetic and transition form factors. Our
result shows that it is essential to use the constituent quark mass instead of
the current quark mass in evaluating the anomaly term from the triangle graph.Comment: LaTeX, 14 pages + 4 figures, (figures are included as uuencoded
files), KUNS-1210 HE(TH) 93/0
Low-lying even parity meson resonances and spin-flavor symmetry
A study is presented of the wave meson-meson interactions involving
members of the nonet and of the octet. The starting point is an
SU(6) spin-flavor extension of the SU(3) flavor Weinberg-Tomozawa Lagrangian.
SU(6) symmetry breaking terms are then included to account for the physical
meson masses and decay constants, while preserving partial conservation of the
axial current in the light pseudoscalar sector. Next, the matrix amplitudes
are obtained by solving the Bethe Salpeter equation in coupled-channel with the
kernel built from the above interactions. The poles found on the first and
second Riemann sheets of the amplitudes are identified with their possible
Particle Data Group (PDG) counterparts. It is shown that most of the low-lying
even parity PDG meson resonances, specially in the and sectors,
can be classified according to multiplets of the spin-flavor symmetry group
SU(6). The , and some resonances cannot be
accommodated within this SU(6) scheme and thus they would be clear candidates
to be glueballs or hybrids. Finally, we predict the existence of five exotic
resonances ( and/or ) with masses in the range 1.4--1.6 GeV,
which would complete the , , and multiplets of
SU(3)SU(2).Comment: 43 pages, 2 figures, 61 tables. Improved discussion of Section II. To
appear in Physical Review
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