1,898 research outputs found
Framework for Identification of Neutral B Mesons
We introduce a method for the study of CP-violating asymmetries in tagged
states of neutral mesons with arbitrary coherence properties. A set of
time-dependent measurements is identified which completely specifies the
density matrix of the initial state in a two-component space with basis vectors
and , and permits a determination of phases in the
Cabibbo-Kobayashi-Maskawa matrix. For a given tagging configuration, the
measurement of decays both to flavor eigenstates and to CP eigenstates provides
the necessary information.Comment: Submitted to Phys. Rev. Letters. 8 pages, LaTeX, Technion-PH-93-31 /
EFI 93-3
An interacting quark-diquark model of baryons
A simple quark-diquark model of baryons with direct and exchange interactions
is constructed. Spectrum and form factors are calculated and compared with
experimental data. Advantages and disadvantages of the model are discussed.Comment: 13 pages, 3 eps-figures, accepted by Phys.Rev. C Rapid Communication
Comment on Octet Baryon Magnetic Moments in the Chiral Quark Model with Configuration Mixing
The importance of exchange currents, and of conserving isotopic spin at both
the quark and baryon levels in application of the chiral quark model to any
calculation of baryon magnetic moments is emphasized.Comment: 5 pages, Latex fil
Entangling photons via the double quantum Zeno effect
We propose a scheme for entangling two photons via the quantum Zeno effect,
which describes the inhibition of quantum evolution by frequent measurements
and is based on the difference between summing amplitudes and probabilities.
For a given error probability , our scheme requires that the
one-photon loss rate and the two-photon absorption rate
in some medium satisfy , which is significantly improved in comparison to previous
approaches. Again based on the quantum Zeno effect, as well as coherent
excitations, we present a possibility to fulfill this requirement in an
otherwise linear optics set-up.Comment: 4 pages RevTeX, 2 figure
Isoscalar-isovector mass splittings in excited mesons
Mass splittings between the isovector and isoscalar members of meson nonets
arise in part from hadronic loop diagrams which violate the Okubo-Zweig-Iizuka
rule.
Using a model for these loop processes which works qualitatively well in the
established nonets, I tabulate predictions for the splittings and associated
isoscalar mixing angles in the remaining nonets below about 2.5 GeV, and
explain some of their systematic features.
The results for excited vector mesons compare favorably with experiment.Comment: 8 RevTeX pages, including 1 LaTeX figure.
CMU-HEP93-23/DOE-ER-40682-4
Broken SU(3) Symmetry in Two-Body B Decays
The decays of mesons to two-body hadronic final states are analyzed
within the context of broken flavor SU(3) symmetry, extending a previous
analysis involving pairs of light pseudoscalars to decays involving one or two
charmed quarks in the final state. A systematic program is described for
learning information {}from decay rates regarding (i) SU(3)-violating
contributions, (ii) the magnitude of exchange and annihilation diagrams
(effects involving the spectator quark), and (iii) strong final-state
interactions. The implication of SU(3)-breaking effects for the extraction of
weak phases is also examined. The present status of data on these questions is
reviewed and suggestions for further experimental study are made.Comment: 38 pages, 8 figures, LaTeX file. The full postscript manuscript is
available by anon ftp at
ftp://lpsvsh.lps.umontreal.ca/theorie/hep-ph/SU3break.ps (a VAX so use the
format theorie.hep-ph if you change by more than one directory at a time
Final State Interactions and New Physics in B -> pi K Decays
Within the Standard Model, and if one assumes that soft rescattering effects
are negligible, the CP asymmetry A^dir_CP (B^\pm -> \pi^\pm K) is predicted to
be very small and the ratio R = BR(B_d -> \pi^\mp K^\pm)/BR(B^\pm -> \pi^\pm K)
provides a bound on the angle \gamma of the unitarity triangle, sin^2 \gamma
\leq R. We estimate the corrections from soft rescattering effects using an
approach based on Regge phenomenology, and find effects of order 10% with large
uncertainties. In particular, we conclude that A^dir_CP \sim 0.2 and sin^2
\gamma \sim 1.2 R could not be taken unambiguously to signal New Physics. Using
SU(3) relations, we suggest experimental tests that could constrain the size of
the soft rescattering effects thus reducing the related uncertainty. Finally,
we study the effect of various models of New Physics on A^dir_CP and on R.Comment: 20 pages, RevTex, no figures; a few typos corrected, references
added, brief additional discussion of uncertanties is adde
Model-independent analysis for determining mass splittings of heavy baryons
We study the hyperfine mass differences of heavy hadrons in the heavy quark
effect theory (HQET). The effects of one-gluon exchange interaction are
considered for the heavy mesons and baryons. Base on the known experimental
data, we predict the masses of some heavy baryons in a model-independent way.Comment: 14 pages, 1 figur
Beyond the relativistic mean-field approximation (II): configuration mixing of mean-field wave functions projected on angular momentum and particle number
The framework of relativistic self-consistent mean-field models is extended
to include correlations related to the restoration of broken symmetries and to
fluctuations of collective variables. The generator coordinate method is used
to perform configuration mixing of angular-momentum and particle-number
projected relativistic wave functions. The geometry is restricted to axially
symmetric shapes, and the intrinsic wave functions are generated from the
solutions of the relativistic mean-field + Lipkin-Nogami BCS equations, with a
constraint on the mass quadrupole moment. The model employs a relativistic
point-coupling (contact) nucleon-nucleon effective interaction in the
particle-hole channel, and a density-independent -interaction in the
pairing channel. Illustrative calculations are performed for Mg,
S and Ar, and compared with results obtained employing the model
developed in the first part of this work, i.e. without particle-number
projection, as well as with the corresponding non-relativistic models based on
Skyrme and Gogny effective interactions.Comment: 37 pages, 10 figures, submitted to Physical Review
Why is the B -> eta' X decay width so large ?
New mechanism for the observed inclusive B -> \eta'X decay is suggested. We
argue that the dominant contribution to this amplitude is due to the Cabbibo
favored b -> \bar{c}cs process followed by the transition \bar{c}c -> \eta'. A
large magnitude of the "intrinsic charm" component of \eta' is of critical
importance in our approach. Our results are consistent with an unexpectedly
large Br(B -> \eta'+X) \sim 10^{-3} recently announced by CLEO. We stress the
uniqueness of this channel for 0^{-+} gluonia search.Comment: Comments on a mixing model for intrinsic charm and pre-asymptotic
effects and some references are added. Latex, 9 page
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