8 research outputs found
Nucleon distribution amplitudes from lattice QCD
We calculate low moments of the leading-twist and next-to-leading twist
nucleon distribution amplitudes on the lattice using two flavors of clover
fermions. The results are presented in the MSbar scheme at a scale of 2 GeV and
can be immediately applied in phenomenological studies. We find that the
deviation of the leading-twist nucleon distribution amplitude from its
asymptotic form is less pronounced than sometimes claimed in the literature.Comment: 5 pages, 3 figures, 2 tables. RevTeX style. Normalization for
\lambda_i corrected. Discussion of the results extended. To be published in
PR
Non-perturbative renormalization of three-quark operators
High luminosity accelerators have greatly increased the interest in
semi-exclusive and exclusive reactions involving nucleons. The relevant
theoretical information is contained in the nucleon wavefunction and can be
parametrized by moments of the nucleon distribution amplitudes, which in turn
are linked to matrix elements of local three-quark operators. These can be
calculated from first principles in lattice QCD. Defining an RI-MOM
renormalization scheme, we renormalize three-quark operators corresponding to
low moments non-perturbatively and take special care of the operator mixing.
After performing a scheme matching and a conversion of the renormalization
scale we quote our final results in the MSbar scheme at mu=2 GeV.Comment: 49 pages, 3 figure
Nucleon wave function from lattice QCD
In this work we develop a systematic approach to calculate moments of leading-twist and next-to-leading twist baryon distribution amplitudes within lattice QCD. Using two flavours of dynamical clover fermions we determine low moments of nucleon distribution amplitudes as well as constants relevant for proton decay calculations in grand unified theories. The deviations of the leading-twist nucleon distribution amplitude from its asymptotic form, which we obtain, are less pronounced than sometimes claimed in the literature. The results are applied within the light cone sum rule approach to calculate nucleon form factors that are compared with recent experimental data
Nucleon distribution amplitudes and proton decay matrix elements on the lattice
Baryon distribution amplitudes (DAs) are crucial for the theory of hard
exclusive reactions. We present a calculation of the first few moments of the
leading-twist nucleon DA within lattice QCD. In addition we deal with the
normalization of the next-to-leading (twist-four) DAs. The matrix elements
determining the latter quantities are also responsible for proton decay in
Grand Unified Theories. Our lattice evaluation makes use of gauge field
configurations generated with two flavors of clover fermions. The relevant
operators are renormalized nonperturbatively with the final results given in
the MSbar scheme. We find that the deviation of the leading-twist nucleon DA
from its asymptotic form is less pronounced than sometimes claimed in the
literature.Comment: 24 pages, 22 figure