Randal Milton Hans
Ph.D. Thesis
Yale University

Graduated: May 1996
Defended : January 18, 1996
Advisor: Michael P. Schmidt

Title
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Polarization in Vector-Vector Decay of B Mesons at CDF 

Abstract
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The factorization assumption in bound state decays (splitting
four-quark operators into the product of two two-quark operators) has
proved to be a useful tool in B and D meson decays.  The longitudinal
polarization fraction, Gamma_L/Gamma, in the decays B_d -> J/psi K^*0
and B_s -> J/psi phi can be calculated using various phenomenological
models within the factorization assumption and, when compared to
experimental measurements, provides a test of the factorization
procedure when extended to color-suppressed B decays.

The decay B_d -> J/psi K^*0, K^*0 -> K_s pi^0 can be used to study CP
violation in the same manner as in the decay B -> J/psi K_s.  In
general the decay B_d -> J/psi K^*0 is a mix of CP-even and CP-odd 
states (diluting the measured CP asymmetry), but when 
Gamma_L/\Gamma = 1 (as indicated by early measurements) the decay is 
CP-even.

The longitudinal polarization fractions in the decays 
B_d -> J/psi K^*0 and B_s -> J/psi phi have been measured using data 
collected with the Collider Detector at Fermilab.   B_d mesons are
reconstructed through the decay chain B_d -> J/psi K^*0,
J/psi-> mu^+ mu^-, K^*0 -> K^+ pi^-.  A sample of 65 +/- 10 B_d events 
is used to obtain a longitudinal polarization fraction of 
\Gamma_L/\Gamma = 0.65 +/- 0.10 (stat) +/- 0.04 (sys). 
B_s mesons are reconstructed through the decay chain
B_s -> J/psi phi, J/psi -> mu^+ mu^-, \phi -> K^+ K^-. A sample of 
19 +/- 5 B_s events is used to obtain the result 
\Gamma_L/\Gamma = 0.56 +/- 0.21 (stat) +0.02 -0.04 (sys).

The B_d result is consistent with, although slightly lower than,
previous measurements and is at the upper edge of the theoretical
predictions.  This result has also shown that \Gamma_L/\Gamma != 1, 
so another analysis technique (requiring more data) will be needed
to extract the CP content of the decay B_d -> J/psi K^*0, 
$K^*0 -> K_s pi^0.


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    http://www-cdf.fnal.gov/thesis/cdf4786_hans_thesis.ps

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