894 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
Topology, Locality, and Aharonov-Bohm Effect with Neutrons
Recent neutron interferometry experiments have been interpreted as
demonstrating a new topological phenomenon similar in principle to the usual
Aharonov-Bohm (AB) effect, but with the neutron's magnetic moment replacing the
electron's charge. We show that the new phenomenon, called Scalar AB (SAB)
effect, follows from an ordinary local interaction, contrary to the usual AB
effect, and we argue that the SAB effect is not a topological effect by any
useful definition. We find that SAB actually measures an apparently novel spin
autocorrelation whose operator equations of motion contain the local torque in
the magnetic field. We note that the same remarks apply to the Aharonov-Casher
effect.Comment: 9 page
Low-Mass Baryon-Antibaryon Enhancements in B Decays
The nature of low-mass baryon-antibaryon enhancements seen in B decays is
explored. Three possibilities include (i) states near threshold as found in a
model by Nambu and Jona-Lasinio, (ii) isoscalar states with coupled to a pair of gluons, and (iii) low-mass enhancements favored by the
fragmentation process. Ways of distinguishing these mechanisms using angular
distributions and flavor symmetry are proposed.Comment: 8 pages, LaTeX, no figures, to be submitted to Phys. Rev. D. One
reference adde
On the equivalence of pairing correlations and intrinsic vortical currents in rotating nuclei
The present paper establishes a link between pairing correlations in rotating
nuclei and collective vortical modes in the intrinsic frame. We show that the
latter can be embodied by a simple S-type coupling a la Chandrasekhar between
rotational and intrinsic vortical collective modes. This results from a
comparison between the solutions of microscopic calculations within the HFB and
the HF Routhian formalisms. The HF Routhian solutions are constrained to have
the same Kelvin circulation expectation value as the HFB ones. It is shown in
several mass regions, pairing regimes, and for various spin values that this
procedure yields moments of inertia, angular velocities, and current
distributions which are very similar within both formalisms. We finally present
perspectives for further studies.Comment: 8 pages, 4 figures, submitted to Phys. Rev.
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
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
Charmless decays using flavor SU(3) symmetry
The decays of mesons to a pair of charmless pseudoscalar () mesons are
analyzed within a framework of flavor SU(3). Symmetry breaking is taken into
account in tree () amplitudes through ratios of decay constants; exact SU(3)
is assumed elsewhere. Acceptable fits to and
branching ratios and CP asymmetries are obtained with tree, color-suppressed
(), penguin (), and electroweak penguin () amplitudes. Crucial
additional terms for describing processes involving and include
a large flavor-singlet penguin amplitude () as proposed earlier and a
penguin amplitude associated with intermediate and quarks. For
the mode a term associated with intermediate
and quarks also may be needed. Values of the weak phase are
obtained consistent with an earlier analysis of decays, where
denotes a vector meson, and with other analyses of CKM parameters.Comment: 26 pages, 1 figure. To be submitted to Phys. Rev. D. Reference
update
A method for determining CP violating phase
A new way of determining the phases of weak amplitudes in charged decays
based on SU(3) symmetry is proposed. The CP violating phase can now be
determined without the previous difficulty associated with electroweak
penguins.Comment: 9 pages plus one figure, Revte
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