290 research outputs found
Weak Coupling Phase from Decays of Charged B Mesons to and
The theory of violation based on phases in weak couplings in the
Cabibbo-Kobayashi-Maskawa (CKM) matrix requires the phase (in a standard convention) to be nonzero. A measurement of
is proposed based on charged meson decay rates to ,
, , and the charge-conjugate states. The corresponding
branching ratios are expected to be of the order of . (submitted to
Physical Review Letters)Comment: LaTeX, 8 pages, 2 figures (not included, available upon request),
TECHNION-PH-94-7, EFI-94-14, UdeM-LPN-TH-94-19
Forward-Backward Asymmetries in Hadronically Produced Lepton Pairs
It has now become possible to observe appreciable numbers of hadronically
produced lepton pairs in mass ranges where the contributions of the photon and
are comparable. Consequently, in the reaction , substantial forward-backward asymmetries can be seen. These
asymmetries provide a test of the electroweak theory in a new regime of
energies, and can serve as diagnostics for any new neutral vector bosons
coupling both to quarks and to charged lepton pairs.Comment: 11 pages, latex, 4 uuencoded figures sent separately, Fig. 2 revise
Annihilation, Rescattering, and CP Asymmetries in B Meson Decays
A number of meson decays may proceed only through participation of the
spectator quark, whether through amplitudes proportional to or via
rescattering from other less-suppressed amplitudes. An expected hierarchy of
amplitudes in the absence of rescattering will be violated by rescattering
corrections. Such violations could point the way toward channels in which
final-state interactions could be important. Cases in which final state phases
can lead to large CP asymmetries are pointed out.Comment: 9 page
Atomic Parity Violation and Precision Electroweak Physics - An Updated Analysis
A new analysis of parity violation in atomic cesium has led to the improved
value of the weak charge, . The implications
of this result for constraining the Peskin-Takeuchi parameters S and T and for
guiding searches for new Z bosons are discussed.Comment: 8 pages, LaTeX, 3 figures, Submitted to Physical Review D. Updated
experimental inputs and references; clarification of notatio
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
An E interpretation of an event
The lowest-dimensional representation of the group E contains both the
standard quarks and leptons and a set of exotic quarks and leptons whose decays
can involve a series of chains ending in radiative decay of one light neutrino
species to another. An example is given based on the decomposition E
SU(2) SU(6), where SU(2) is an ``inert'' subgroup whose gauge
bosons and are all electromagnetically neutral, while SU(6)
contains the conventional SU(5) grand-unified group. The possibility is
explored that such a chain is responsible for an event observed by the Collider
Detector at Fermilab (CDF) involving the production in proton-antiproton
collisions at TeV of an electron-positron pair, two
photons, and missing energy ().Comment: 14 pages, latex, no figures. Revised version submitted to PR
Role of Present and Future Atomic Parity Violation Experiments in Precision Electroweak Tests
Recent reanalyses of the atomic physics effects on the weak charge in cesium
have led to a value in much closer agreement with predictions of the Standard
Model. We review precision electroweak tests, their implications for upper
bounds on the mass of the Higgs boson, possible ways in which these bounds may
be circumvented, and the requirements placed upon accuracy of future atomic
parity violation experiments by these considerations.Comment: 10 pages, LaTeX, 1 figure, to be submitted to Physical Review D, new
data on neutrino deep inelastic scattering include
Convention-independent study of CP-violating asymmetries in
CP-violating asymmetries in the decay are a
potentially rich source of information about both strong and weak phases. In a
previous treatment by the present authors use was made of an assumption about
the relative magnitude of tree and penguin amplitudes contributing to this
process. This assumption involved an ambiguity in relating the tree amplitude
to the amplitude for . It is shown here that one can avoid
this assumption, which adopted a particular convention for tree and penguin
amplitudes, and that the results are convention-independent.Comment: 14 pages, LaTeX, 2 figures, revised version submitted to Phys. Rev.
D. Further references and text adde
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
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