Matrix elements of the electromagnetic operator between kaon and pion states

Journal Article · Sat Oct 01 04:00:00 EDT 2011 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.84.074503· OSTI ID:21607798

Baum, I ^[1]; Lubicz, V ^[2]; Martinelli, G ^[3]; Orifici, L ^[2]; Simula, S ^[4]

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1. Dip. di Fisica, Universita di Roma ''La Sapienza'', P.le A. Moro 5, I-00185 Roma (Italy)
2. Dip. di Fisica, Universita Roma Tre, Via della Vasca Navale 84, I-00146 Roma (Italy)
3. SISSA, Via Bonomea 265, I-34136 Trieste (Italy)
4. INFN, Sezione di Roma Tre, Via della Vasca Navale 84, I-00146 Roma (Italy)

We compute the matrix elements of the electromagnetic operator sF{sub {mu}{nu}}{sigma}{sup {mu}{nu}}d between kaon and pion states, using lattice QCD with maximally twisted-mass fermions and two flavors of dynamical quarks (N{sub f}=2). The operator is renormalized nonperturbatively in the RI'/MOM scheme and our simulations cover pion masses as light as 270 MeV and three values of the lattice spacing from {approx_equal}0.07 up to {approx_equal}0.1 fm. At the physical point our result for the corresponding tensor form factor at zero-momentum transfer is f{sub T}{sup K{pi}}(0)=0.417(14{sub stat})(5{sub syst}), where the systematic error does not include the effect of quenching the strange and charm quarks. Our result differs significantly from the old quenched result f{sub T}{sup K{pi}}(0)=0.78(6) obtained by the SPQ{sub cd}R Collaboration with pion masses above 500 MeV. We investigate the source of this difference and conclude that it is mainly related to the chiral extrapolation. We also study the tensor charge of the pion and obtain the value f{sub T}{sup {pi}{pi}}(0)=0.195(8{sub stat})(6{sub syst}) in good agreement with, but more accurate than the result f{sub T}{sup {pi}{pi}}(0)=0.216(34) obtained by the QCDSF Collaboration using higher pion masses.

• OSTI ID: 21607798
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 7 Vol. 84; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
BOSONS
CHIRALITY
COMPOSITE MODELS
DIMENSIONLESS NUMBERS
ELEMENTARY PARTICLES
ENERGY RANGE
EXTRAPOLATION
FERMIONS
FIELD THEORIES
FLAVOR MODEL
FORM FACTORS
HADRONS
KAONS
MASS
MATHEMATICAL MODELS
MATHEMATICAL SOLUTIONS
MATRIX ELEMENTS
MESONS
MEV RANGE
MEV RANGE 100-1000
MOMENTUM TRANSFER
NUMERICAL SOLUTION
PARTICLE MODELS
PARTICLE PROPERTIES
PIONS
PSEUDOSCALAR MESONS
QUANTUM CHROMODYNAMICS
QUANTUM FIELD THEORY
QUARK MODEL
QUARKS
QUENCHING
SIMULATION
STRANGE MESONS
STRANGE PARTICLES