منابع مشابه
Nonlocal Condensates and Pion Form Factor *
〈π(P )|Jμ(0)|π (P )〉 = (P + P ′)μFπ(Q ) , where Jμ is the electromagnetic current and q is the photon momentum q = (P −P ) = −Q < 0 in the spacelike region. For asymptotically large momenta, one can apply the factorization theorem so that the FF will be represented via the inverse moment of the leading-twist pion distribution amplitude (DA). The precise value of Q at which this perturbative ter...
متن کاملPion Form Factor in the Qcd Sum-rule Approach with Nonlocal Condensates *
The pion—its distribution amplitude and form factor—stands tall as a role model for the modern description of hadrons in terms of quarks and gluons within QCD. At high momenta Q2, the pion form factor can be written as a convolution Fπ(Q 2) = φout π ⊗ T (Q 2)⊗ φin π on account of the factorization theorem, where the symbol ⊗ means integration over the longitudinal momenta of the quark and antiq...
متن کاملThe Pion Form Factor
The pion, and specifically its charge form factor, is of key interest in the study of the quark-gluon structure of hadrons. This is exemplified by the many calculations that treat the pion as one of their prime examples. One of the reasons is that the valence structure of the pion, being 〈qq̄〉, is relatively simple. Hence it is expected that the value of the four-momentum transfer squared Q, dow...
متن کاملPerturbative Pion Form Factor Reexamined
We recalculate the pion electromagnetic form factor based on the pertur-bative QCD formalism that includes the Sudakov resummation. We take into account the evolution of the pion wave function in b, which represents the transverse extent of the pion. An infrared enhancement is observed when 1/b approaches Λ QCD. We propose to freeze the evolution of the wave function at some scale above Λ QCD ,...
متن کاملQuark structure of the pion and pion form factor.
We consider the pion structure in the region of low and moderately high momentum transfers: at low Q 2 , the pion is treated as a composite system of constituent quarks; at moderately high momentum transfers, Q 2 = 10 ÷ 25 GeV 2 , the pion form factor is calculated within perturbative QCD taking into account one–gluon hard exchange. Using the data on pion form factor at Q 2 < 3 GeV 2 and pion a...
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ژورنال
عنوان ژورنال: Nuclear Physics B - Proceedings Supplements
سال: 2010
ISSN: 0920-5632
DOI: 10.1016/j.nuclphysbps.2009.12.035