108 research outputs found
Renormalization of HQET operators: O() improvement and matching with QCD
We determine a basis of dimension-7 operators which arise at O() in the
Symanzik expansion of the operators with static heavy quarks. We
consider both Wilson-like and Ginsparg-Wilson light quarks. Exact chiral
symmetry reduces the number of these O() counterterms by a factor of two.
Only a subset of these operators has previously appeared in the literature. We
then extend the analysis to the O() operators contributing beyond the
static approximation.Comment: 7 pages, presented at the 31st International Symposium on Lattice
Field Theory (Lattice 2013), 29 July - 3 August 2013, Mainz, German
Non-perturbative scale evolution of four-fermion operators in two-flavour QCD
We apply finite-size recursion techniques based on the Schrodinger functional
formalism to determine the renormalization group running of four-fermion
operators which appear in the Delta S=2 effective weak Hamiltonian of the
Standard Model. Our calculations are done using O(a) improved Wilson fermions
with N_f=2 dynamical flavours. Preliminary results are presented for the
four-fermion operator which determines the B_K parameter in tmQCD.Comment: 7 pages, 2 figures, talk presented at Lattice2006 (Renormalization
Renormalisation of quark bilinears with Nf=2 Wilson fermions and tree-level improved gauge action
We present results for the renormalisation constants of bilinear quark
operators, using the Nf=2 twisted mass Wilson action at maximal twist (which
guarantees automatic O(a) improvement) and the tree-level Symanzik improved
gauge action. The scale-independent renormalisation constants are computed with
a new method, which makes use of both standard twisted mass and
Osterwalder-Seiler fermions. Moreover, the results from an RI-MOM calculation
are presented for both scale independent and scale dependent renormalisation
constants.Comment: 7 pages, talk at The XXV International Symposium on Lattice Field
Theory, July 30 - August 4 2007, Regensbur
The Pion Light-Cone Wave Function Phi_pi on the lattice: a partonic signal?
We determine the conditions required to study the pion light-cone wave
function Phi_pi with a new method: a direct display of the partons constituting
the pion. We present the preliminary results of a lattice computation of Phi_pi
following this direction. An auxiliary scalar-quark is introduced. The
spectroscopy of its bound states is studied. We observe some indications of a
partonic behavior of the system of this scalar-quark and the anti-quark.Comment: 3 pages, 4 figures, Lattice2001(matrixelement
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