Lattice2010

Session

Parallel 17: Weak decays and matrix elements

15 Jun 2010, 08:30

Villasimius, Sardinia

98. Computing the long-distance contribution to second order weak amplitudes

Norman Christ (Columbia University)

15/06/2010, 08:30

Weak decays and matrix elements

The calculation of the long-distance contribution to the K^0-\overline{K}_0 mass matrix is divided into three parts: First, the calculation of the matrix element between kaon states of the product of two space-time integrated, $\Delta S=1$, four-quark weak operators. Second an RI/MOM subtraction to remove the short distance part of this matrix element in a fashion consistent with...

290. Preliminary study of the non-perturbative renormalization of K-> pi (pi) operators, with Nf=2+1 Domain Wall fermions

Nicolas Garron (University of Edinburgh)

15/06/2010, 08:50

Weak decays and matrix elements

At the leading order of the OPE, they are ten 4-quark operators which contribute to the \Delta S=1 effective Hamiltonian. The mixing pattern of these operators under renormalization is governed by their chiral properties. Thus it is crucial to perform this computation with fermions which preserve (or almost preserve) chiral symmetry, such as Domain Wall fermions. We present here our...

11. $\Delta I = 3/2$, $K \to \pi \pi$ Matrix Elements with Nearly Physical Pion Masses

Matthew Lightman (Columbia University)

15/06/2010, 09:10

Weak decays and matrix elements

$\Delta I = 3/2$ channel $K\to\pi\pi$ matrix elements are calculated with a variety of kaon masses, pion masses, and pion momenta on quenched $24^3\times 64$, $L_s=16$ lattices using the DBW2 action and domain wall fermions. After an interpolation in pion momentum to energy conserving kinematics is performed, the dependence of the matrix elements on $m_\pi$ and $m_K$ is studied. The lightest...

9. Preliminary results of $\Delta I=1/2$ and $3/2$, $K$ to $\pi\pi$ Decay Amplitudes from Lattice QCD

Qi Liu (Columbia University)

15/06/2010, 09:30

Weak decays and matrix elements

We report a direct lattice calculation of the $K$ to $\pi\pi$ decay matrix elements for both $\Delta I=1/2$ and $3/2$ channels on 2+1 flavor, domain wall fermion, $16^3\times32$ lattices. All possible contractions are carefully listed and calculated and identities among them are verified. The decay into the isospin zero $\pi\pi$ final state, which receives contributions from the disconnected...

325. Matrix element of the electromagnetic operator between kaon and pion states

Itzhak Baum (Rome University "La Sapienza")

15/06/2010, 09:50

Weak decays and matrix elements

We investigate the calculation of the matrix element of the electromagnetic operator between kaon and pion states, using maximally twisted-mass fermions with two flavors of dynamical quarks. The operator is renormalized non-perturbatively and our simulations at different values of the lattice spacing and pion masses are extrapolated to the continuum limit and to the physical kaon and pion masses.