Related papers: Four-quark operators in hadrons
Nucleon matrix elements of various four-quark operators are evaluated in quenched lattice QCD using Wilson fermions. Some of these operators give rise to twist-four contributions to nucleon structure functions. Furthermore, they bear…
We presents results for the matrix elements of a variety of four-fermion operators calculated using quenched Wilson fermions. Our simulations are done on 170 lattices of size $32^3 x 64$ at $\beta = 6.0$. We find $B_K=0.74 +- 0.04 +- 0.05$,…
Four-fermion operators have been utilized in the past to link the quark-exchange processes in the interaction of hadrons with the effective meson-exchange amplitudes. In this paper, we apply the similar idea of a Fierz rearrangement to the…
We evaluate the contribution of a class of higher-twist operators to the lowest moment of the Structure Functions, by computing appropriate matrix elements of six four-fermion operators in the quenched approximation. Their perturbative…
We report preliminary results of our study of matrix elements of baryon number violating operators which appear in the low-energy effective Lagrangian of (SUSY-)Grand Unified Theories. The calculation is performed on a $32^{3}\times80$…
We present quenched lattice QCD results for the contribution of higher-twist operators to the lowest non-trivial moment of the pion structure function. To be specific, we consider the combination $F_2^{\pi^+} + F_2^{\pi^-} - 2 F_2^{\pi^0}$…
We discuss how the peculiar properties of maximally twisted Wilson fermions can be exploited to set up a consistent LQCD computational scheme in which the CP-conserving matrix elements of the $\Delta S =1,2$ effective weak Hamiltonian can…
We calculate expectation values of QCD operators consisting of the products of the four operators of the light quarks corresponding to the scalar, pseudoscalar, vector, pseudovector (axial) and tensor Lorentz structures in the nucleon. All…
A previously-proposed method of constructing spatially-extended gauge-invariant three-quark operators for use in Monte Carlo lattice QCD calculations is tested, and a methodology for using these operators to extract the energies of a large…
We introduce and study the properties of the "color-straight" four-quark operators containing heavy and light quark fields. They are of the form (\bar b\Gamma_b b)(\bar q\Gamma_q q) where both brackets are color singlets. Their expectation…
Four-fermion operators may have large anomalous scaling and become relevant operators in some strongly interacting gauge theories. We present a detailed model which illustrates some of the implications of such operators for the generation…
Our aim is to compute the lower moments of the unpolarized and polarized deep-inelastic structure functions of the nucleon on the lattice. The theoretical basis of the calculation is the operator product expansion. To construct operators…
We compute the matrix elements of the electromagnetic (EM) operator (\bar{s} F{\mu \nu} \sigma{\mu \nu} d) between kaon and pion states, using lattice QCD with maximally twisted-mass fermions and two flavors of dynamical quarks (Nf = 2).…
We investigate the nonperturbative renormalisation of composite operators in lattice QCD restricting ourselves to operators that are bilinear in the quark fields. These include operators which are relevant to the calculation of moments of…
We investigate the nonperturbative renormalization of composite operators in lattice QCD restricting ourselves to operators that are bilinear in the quark fields. These include operators which are relevant to the calculation of moments of…
We report on our computation of the hadronic matrix elements of the four-quark operators needed for the study of $K^0-{\bar K^0}$ mixing beyond the Standard Model (SM). We consider nf=2+1 Domain-Wall fermions on Iwasaki gauge action with…
We consider the matrix elements of the left-handed flavor-conserving four-quark operators in the nucleon and pion states. Using chiral symmetry, we derive relationships among these matrix elements. We argue that the $\Delta I = 1/2$ rule of…
Using Schroedinger Functional methods, we compute the non-perturbative renormalisation and renormalisation group running of several four-fermion operators, in the framework of lattice simulations with two dynamical Wilson quarks. Two…
I report on the application of tmQCD techniques to the computation of hadronic matrix elements of four-fermion operators. Emphasis is put on the computation of $B_K$ in quenched QCD performed by the ALPHA Collaboration. The extension of…
Hadron wave functions and form factors can be extracted using four-point correlators. Stochastic techniques are used to estimate the all to all propagators, which are required for the exact calculation of four-point functions. We apply the…