555 research outputs found
Pure Leptonic Radiative Decays and the Annihilation Graph
Pure leptonic radiative decays of heavy-light mesons are calculated using a
very simple non-relativistic model. Dominant contribution originates from
photon emission from light initial quark. We find
and . The importance of these reactions to
clarify the dynamics of the annihilation graph is emphasized.Comment: 7 pages, LaTeX, 3 figure
Studying the scale and q^2 dependence of K^+-->pi^+e^+e^- decay
We extract the K^+-->pi^+e^+e^- amplitude scale at q^2=0 from the recent
Brookhaven E865 high-statistics data. We find that the q^2=0 scale is fitted in
excellent agreement with the theoretical long-distance amplitude. Lastly, we
find that the observed q^2 shape is explained by the combined effect of the
pion and kaon form-factor vector-meson-dominance rho, omega and phi poles, and
a charged pion loop coupled to a virtual photon-->e^+e^- transition.Comment: 8 pages, 3 figure
Transverse Tau Polarization in Decays of the Top and Bottom Quarks in the Weinberg Model of CP Non-conservation
We show that the transverse polarization asymmetry of the -lepton in
the decay is extremely sensitive to CP violating
phases arising from the charged Higgs exchange in the Weinberg model of CP
non-conservation. Qualitatively, the polarization asymmetries are enhanced over
rate or energy asymmetries by a factor of . Thus for optimal values of the parameters the method requires top pairs to be observable rather than needed for rate or energy
asymmetries. We also examine polarization in b decays via and find that it can also be very effective in constraining the CP
violation parameters of the extended Higgs sector.Comment: 11,1 figure, SLAC-PUB-608
On the Possibility of a New Boson X^0 (214 MeV) in Sigma^+ -> p mu^+ mu^-
We consider the existence of the state X^0 (214 MeV) in Sigma^+ -> p mu^+
mu^- decay found by the HyperCP collaboration. We assume that a fundamental
spin zero boson X^0 coupled to quarks leads to flavor changing s -> d X^0
process. We estimate the scalar and pseudoscalar coupling constants by
considering Sigma^+ -> p X^0 and K^+ -> pi^+ X^0 processes, and find that
pseudoscalar coupling dominates. We then evaluate the branching ratios for K_L
-> pi^0 pi^0 X^0, pi^+ pi^- X^0 and Omega^- -> Xi^- X^0 decays. All these rates
are found to be in the measurable ranges. We also comment on X^0 coupling to
muons and constraints from muon g-2.Comment: 6 pages; typos corrected, references added, 7 page
Asymmetry in the decay
We consider the asymmetry in the decay
assuming that a Vector Meson Dominance approach for the
transition gives the dominant contribution. Since in this long-distance
approximation the decay is due to a single quark transition , the angular distribution asymmetry is given by the single positive
asymmetry parameter .
We also discuss the asymmetry in , which is
expected to be between -0.2 and 0.3.Comment: 16 pages,no figures,Late
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