The final public oral examination of John Laiho will take place
on Monday, July 19, 2004 at 1:00 p.m. in Room 202. The examining
committee will consist of Professors A. Soni (Brookhaven National
Laboratory), C. Callan, D. Marlow and S. Staggs. Any other
members of the University wishing to attend the examination may
do so.
The thesis of John Laiho entitled
"Framework for Improved Lattice Calculations of epsilon'/epsilon", has been placed on
deposit on July 7, 2004.
Any member of the University wishing to read the thesis may do
so. Any objections should be submitted to me in writing. The principal
advisor for this work was Professor Amarjit Soni
(Brookhaven National Laboratory). The abstract is below
ABSTRACT
In this work we show that it is possible to construct
epsilon'/epsilon to NLO using both full and partially
quenched chiral perturbation theory (PQChPT) from amplitudes
that are computable using numerical lattice gauge theory. We find that
the electro-weak penguin (Delta I=3/2 and 1/2) contributions to epsilon'/epsilon
in PQChPT can be determined to NLO using only degenerate (m_K=m_pi) K to pi
computations without momentum insertion. All one-loop formulas needed to extract the
necessary NLO constants from the lattice are presented in this work.
Issues pertaining to power divergent contributions, originating from
mixing with lower dimensional operators in a lattice regularization,
are addressed.
In embedding the QCD penguin left-right operator onto PQChPT an ambiguity
arises when the number of light sea quarks is not the physical value of
three, as first emphasized by Golterman and Pallante. In the quenched theory they have pointed out that
there are additional effective operators that appear in the quenched
chiral perturbation theory needed to make contact with K to pi pi
amplitudes at physical kinematics. They have also proposed a
method for determining the leading order low-energy constant,
alpha^NS_q, associated with the new operators. We show that their method
has difficulties due to power divergent contributions and propose a
new method to obtain this constant from the lattice which does not
suffer from this problem. Using this alternative method, we
obtain alpha^NS_q, and show that our value implies a large ambiguity
in the quenched contribution of Q_6 to epsilon'/epsilon.
Daniel Marlow
Chair, Dept. of Physics
