Photon Distribution Amplitudes in QCD
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We develop a consistent technique for the calculation of real photon emission in hard exclusive processes, which is based on the background field formalism and allows a convenient separation of hard electromagnetic and soft hadronic components of the photon. The latter ones are related to matrix-elements of light-cone operators in the electromagnetic background field and can be parametrized in terms of photon distribution amplitudes. We construct a complete set of photon distribution amplitudes up to and including twist-4, for both chirality-conserving and chirality-violating operators. The distribution amplitudes involve several nonperturbative parameters and, most importantly, the magnetic susceptibility of the quark condensate. We review and update previous estimates of the susceptibility and also give new estimates of parameters describing higher-twist amplitudes from QCD sum rules.
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Forward citations
Cited by 2 Pith papers
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Deciphering the nature of $P^{\Sigma}_{\psi s}$ pentaquarks in the light of their electromagnetic multipole moments
Electromagnetic moments of Σ-type pentaquarks are computed via light-cone sum rules, yielding flavor-sensitive magnetic dipoles, quadrupoles, and octupoles that distinguish diquark types and rule out S-wave molecules.
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Deciphering the nature of $P^{\Sigma}_{\psi s}$ pentaquarks in the light of their electromagnetic multipole moments
QCD light-cone sum rules computation of magnetic dipole, electric quadrupole, and magnetic octupole moments for Σ-type P_ψs pentaquarks, with quark-flavor decomposition and model discriminants.
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