期刊
4TH INTERNATIONAL HADRON PHYSICS CONFERENCE (TROIA'14)
卷 562, 期 -, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/1742-6596/562/1/012002
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资金
- RPF (Cyprus) [TECHNOLOGY/E)E1ID:/0311(BE)/16. I)]
- Mauro in Ricerca [RIFR10.0360]
We study matrix elements of the chromomagnetic operator on the lattice. This operator is contained in the strangeness-changing effective Hamiltonian which describes electroweak effects in the StandardModel and beyond. Having dimension 5, the chromomagnetic operator is characterized by a rich pattern of mixing with other operators of equal and lower dimensionality, including also non gauge invariant quantities; it is thus quite a challenge to extract from lattice simulations a clear signal for the hadronic matrix elements of this operator. We compute all relevant mixing coefficients to one loop in lattice perturbation theory; this necessitates calculating both 2-point (quark-antiquark) and 3-point (gluon-quark-antiquark) Green's functions at nonzero quark masses. We use the twisted mass lattice formulation, with Symanzik improved gluon action. We also provide a nonperturbative method to compute mixing with lower dimensional operators; we use this method in numerical simulations, and extract the mixing with the 3-dimensional scalar density, finding good agreement with one-loop results.
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