Lattice QCD calculation of the proton decay matrix element in the continuum limit

We present a quenched lattice QCD calculation of the alpha and beta parameters of the proton decay matrix element. The simulation is carried out using the Wilson quark action at three values of the lattice spacing in the range aapprox 0.1-0.064 fm to study the scaling violation effect. We find only mild scaling violation when the lattice scale is determined by the nucleon mass. We obtain in the continuum limit, |alpha(NDR,2GeV)|=0.0090(09)(^{+5}_{-19})GeV^3 and |beta(NDR,2GeV)|=0.0096(09)(^{+6}_{-20})GeV^3 with alpha and beta in a relatively opposite sign, where the first error is statistical and the second is due to the uncertainty in the determination of the physical scale.

Continuum limit of proton decay matrix elements in quenched lattice QCD

We present a lattice QCD calculation of the parameters alpha and beta which are necessary in the theoretical estimation of the proton lifetime in grand unified theories (GUTs) using chiral lagrangian approach. The simulation is carried out using the Wilson quark action at three gauge coupling constants in the quenched approximation. We obtain |alpha(2GeV)|=0.0091(08)(^{+10}_{-19})GeV^3 and |beta(2GeV)|=0.0098(08)(^{+10}_{-20})GeV^3 in the continuum limit where the first error is statistical and the second one is due to scale setting.