81 research outputs found
Mixed basis matrix elements for the subgroup reductions of SO(2,1)
By using the irreducible decomposition on the two-dimensional light cone, the mixed basis matrix elements for the three subgroup reductions of SO(2,1) are calculated. These matrix elements are calculated for the principal series only and can be expressed in terms of well-known special functions. As a consequence of appearing in this context, some new properties of these special functions are given
Bounds on gamma from CP violation measurements in B -> pi+ pi- and B -> psi K_S
We study the determination of gamma from CP-violating observables in B -> pi+
pi- and B -> psi K_S. This determination requires theoretical input to one
combination of hadronic parameters. We show that a mild assumption about this
quantity may allow bounds to be placed on gamma, but we stress the pernicious
effects that an eightfold discrete ambiguity has on such an analysis. The
bounds are discussed as a function of the direct (C) and interference (S)
CP-violating observables obtained from time-dependent B -> pi+ pi- decays, and
their behavior in the presence of new physics effects in B-Bbar mixing is
studied. (V2: Misprints corrected. Slightly improved discussion.)Comment: 11 pages, RevTex 4, 5 eps figures include
Detecting new physics contributions to the D0-D0bar mixing through their effects on B decays
New physics effects may yield a detectable mass difference in the D0-D0bar
system, Delta m_D. Here we show that this has an important impact on some B -->
D decays. The effect involves a new source of CP violation, which arises from
the interference between the phases in the B --> D decays and those in the
D0-D0bar system. This interference is naturally large. New physics may well
manifest itself through Delta m_D contributions to these B decays.Comment: 10 pages, Revtex, no figures. To appear in PR
Light Baryon Resonances: Restrictions and Perspectives
The problem of nucleon resonances N' with masses below the Delta is
considered. We derive bounds for the properties of such states. Some of these
are new, while others improve upon existing limits. We discuss the nature of N'
states, and their unitary partners, assuming their existence can be verified.Comment: 11 pages, 11 figur
Comment on "Hara's theorem in the constituent quark model"
It is pointed out that current conservation alone does not suffice to prove
Hara's theorem as it was claimed recently. By explicit calculation we show that
the additional implicit assumption made in such "proofs" is that of a
sufficiently localized current.Comment: 8 pages, Late
Momentum Spectra in the Current Region of the Breit Frame in Deep Inelastic Scattering at HERA
The production of charged particles has been measured in deep inelastic
scattering (DIS) with the ZEUS detector. The evolution of the moments of the
scaled momenta distributions in and has been investigated in the
current fragmentation region of the Breit frame. The results in the current
region are compared to data and QCD analytical calculations. The
results are consistent with the universality of single-particle spectra in DIS
and annihilation at high The results at low disagree with
analytical calculations based on the modified leading log approximation (MLLA)
and local parton hadron duality (LPHD).Comment: 3 pages. 1 postscript figure + 1 postscript preprint logo + 1 LaTeX
file + 1 style fil
Simple Classification of Light Baryons
We introduce a classification number which describes the baryon mass
information in a fuzzy manner. According to and of baryons, we put
all known light baryons in a simple table in which some baryons with same (,
) are classified as members of known octets or decuplets. Meanwhile, we
predict two new possible octets.Comment: 5 latex pages, 5 tables, no figur
Resonance reactions and enhancement of weak interactions in collisions of cold molecules
With the creation of ultracold atoms and molecules, a new type of chemistry -
"resonance" chemistry - emerges: chemical reactions can occur when the energy
of colliding atoms and molecules matches a bound state of the combined molecule
(Feshbach resonance). This chemistry is rather similar to reactions that take
place in nuclei at low energies. In this paper we suggest some problems for
future experimental and theoretical work related to the resonance chemistry of
ultracold molecules. Molecular Bose-Einstein condensates are particularly
interesting because in this system collisions and chemical reactions are
extremely sensitive to weak fields; also, a preferred reaction channel may be
enhanced due to a finite number of final states. The sensitivity to weak fields
arises due to the high density of narrow compound resonances and the
macroscopic number of molecules with kinetic energy E=0 (in the ground state of
a mean-field potential). The high sensitivity to the magnetic field may be used
to measure the distribution of energy intervals, widths, and magnetic moments
of compound resonances and study the onset of quantum chaos. A difference in
the production rate of right-handed and left-handed chiral molecules may be
produced by external electric and magnetic fields and the finite width of the
resonance. The same effect may be produced by the parity-violating energy
difference in chiral molecules.Comment: 5 pages. Included discussion of expected size of effect
Weak radiative hyperon decays, Hara's theorem and the diquark
Weak radiative hyperon decays are discussed in the diquark-level approach. It
is pointed out that in the general diquark formalism one may reproduce the
experimentally suggested pattern of asymmetries, while maintaining Hara's
theorem in the SU(3) limit. At present, however, no detailed quark-based model
of parity-violating diquark-photon coupling exists that would have the
necessary properties.Comment: 10 pages, LaTe
Comment on ``Evidence for Narrow Baryon Resonances in Inelastic pp Scattering''
Compton scattering data are sensitive to the existence of low-mass resonances
reported by Tatischeff et al. We show that such states, with their reported
properties, are excluded by previous Compton scattering experiments.Comment: One page, submitted to PR
- …