Nonlocal condensate model for QCD sum rules |
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Authors: | Ron-Chou Hsieh Hsiang-nan Li |
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Affiliation: | 1. Institute of Physics, Academia Sinica, Taipei, 115, Taiwan;2. Department of Physics, National Tsing-Hua University, Hsinchu, 300, Taiwan;3. Department of Physics, National Cheng-Kung University, Tainan, 701, Taiwan;4. Institute of Applied Physics, National Cheng-Chi University, Taipei, 116, Taiwan |
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Abstract: | We include effects of nonlocal quark condensates into QCD sum rules (QSR) via the Källén–Lehmann representation for a dressed fermion propagator, in which a negative spectral density function manifests their nonperturbative nature. Applying our formalism to the pion form factor as an example, QSR results are in good agreement with data for momentum transfer squared up to Q2≈10 GeV2. It is observed that the nonlocal quark condensate contribution descends like 1/Q2, different from the exponential decrease in Q2 obtained in the literature, and contrary to the linear rise in the local-condensate approximation. |
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Keywords: | QCD sum rules Nonlocal condensate Dressed propagator |
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