Pion form factor in QCD at intermediate momentum transfers

Braun, Vladimir M.; Khodjamirian, Alexander; Maul, M.

doi:10.1103/physrevd.61.073004

Cited by 147 publications

(249 citation statements)

References 57 publications

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“…They appear at proper order in α s , i.e., in the O(α s ) term for the pion form factor, at the α 2 s order for the nucleon form factors, etc. In the pion case, it was explicitly demonstrated [26,27] that the contribution of hard rescattering is correctly reproduced in the LCSR approach as a part of the O(α s ) correction. It should be noted that the diagrams of LCSR that contain the "hard" pQCD contributions also possess "soft" parts, i.e., one should perform a separation of "hard" and "soft" terms inside each diagram.…”

Section: Introductionmentioning

confidence: 99%

Deep inelastic pion electroproduction at threshold

et al. 2007

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We consider the cross section of the deep inelastic pion electroproduction on a proton target at threshold for Q 2 in the region 5 − 10 GeV 2 . The corresponding amplitudes are described in terms of two form factors which we calculate using light cone sum rules (LCSR) to leading order in QCD and including higher twist corrections. Our results suggest a considerable change from a small Q 2 region that can be treated in the soft pion limit using current algebra. In particular, we obtain a π 0 to π + producton ratio of order 1/3 and significant nucleon helicity-flip contributions.

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Section: Introductionmentioning

confidence: 99%

Deep inelastic pion electroproduction at threshold

et al. 2007

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“…1 Both soft and hard contributions to the Λ b → Λ form factors can be computed in the framework of the LCSR approach, however, two-loop computation of the vacuum-to-Λ b -baryon correlation function is in demand to facilitate the comparison with the hard contributions calculated in TMD factorization. A detailed analysis of the interplay of soft and hard contributions for the Λ b → Λ form factors, along the lines of [30] for the electromagnetic pion form factor, is certainly interesting but beyond the scope of this paper.…”

Section: Jhep02(2016)179mentioning

confidence: 99%

Perturbative corrections to Λ b → Λ form factors from QCD light-cone sum rules

Wang

Shen

2016

J. High Energ. Phys.

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We compute radiative corrections to Λ b → Λ from factors, at next-to-leading logarithmic accuracy, from QCD light-cone sum rules with Λ b -baryon distribution amplitudes. Employing the diagrammatic approach factorization of the vacuum-to-Λ b -baryon correlation function is justified at leading power in Λ/m b , with the aid of the method of regions. Hard functions entering the factorization formulae are identical to the corresponding matching coefficients of heavy-to-light currents from QCD onto soft-collinear effective theory. The universal jet function from integrating out the hard-collinear fluctuations exhibits richer structures compared with the one involved in the factorization expressions of the vacuum-to-B-meson correlation function. Based upon the QCD resummation improved sum rules we observe that the perturbative corrections at O(α s ) shift the Λ b → Λ from factors at large recoil significantly and the dominant contribution originates from the next-to-leading order jet function instead of the hard coefficient functions. Having at hand the sum rule predictions for the Λ b → Λ from factors we further investigate several decay observables in the electro-weak penguin Λ b → Λ + − transitions in the factorization limit (i.e., ignoring the "non-factorizable" hadronic effects which cannot be expressed in terms of the Λ b → Λ from factors), including the invariant mass distribution of the lepton pair, the forward-backward asymmetry in the dilepton system and the longitudinal polarization fraction of the leptonic sector.

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“…6 Still another possibility is to use the analytic coupling [56], as done in [28,29] (see next section). In order to protect the BLM scale from intruding into the forbidden nonperturbative soft region, where perturbation theory becomes invalid, one can make use of a minimum scale, µ min , based on the grounds of QCD factorization theorems and the OPE, as applied for instance in [104,105,106,107] and also in [32]:…”

Section: A Ms Schemementioning

confidence: 99%

“…While it may still be not possible to clarify all these theoretical issues conclusively, we believe that significant progress has quite recently been achieved in understanding the pion structure both from the theoretical side-perturbatively [26,27,28,29,30] and nonperturbatively [1, 31,32,33,34]-as well as from the experimental side [35,36,37] and associated data-processing techniques [38,39,40], a progress that could bring to a cleaner comparison between data and various theoretical QCD predictions [31,39,40,41,42,43,44,45,46,47,48,49]. 1 Moreover, a program to compute the electromagnetic and transition form factors of mesons on the lattice has been launched by two collaborations, [51,52] and [53], that may provide valuable insights when it is completed.…”

Section: Introductionmentioning

confidence: 99%

Publisher's Note: Pion form factor in QCD: From nonlocal condensates to next-to-leading-order analytic perturbation theory [Phys. Rev. D 70, 033014 (2004)]

Bakulev¹,

Passek‐Kumerički²,

Schroers³

et al. 2004

Phys. Rev. D

118

252

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We present an investigation of the pion's electromagnetic form factor F π (Q 2 ) in the spacelike region utilizing two new ingredients: (i) a double-humped, endpoint-suppressed pion distribution amplitude derived before via QCD sum rules with nonlocal condensates-found to comply at the 1σ level with the CLEO data on the πγ transition-and (ii) analytic perturbation theory at the level of parton amplitudes for hadronic reactions. The computation of F π (Q 2 ) within this approach is performed at NLO of QCD perturbation theory (standard and analytic), including the evolution of the pion distribution amplitude at the same order. We consider the NLO corrections to the form factor in the MS scheme with various renormalization scale settings and also in the α Vscheme. We find that using standard perturbation theory, the size of the NLO corrections is quite sensitive to the adopted renormalization scheme and scale setting. The main results of our analysis are the following: (i) Replacing the QCD coupling and its powers by their analytic images, both dependencies are diminished and the predictions for the pion form factor are quasi scheme and scale-setting independent. (ii) The magnitude of the factorized pion form factor, calculated with the aforementioned pion distribution amplitude, is only slightly larger than the result obtained with the asymptotic one in all considered schemes. (iii) Including the soft pion form factor via local duality and ensuring the Ward identity at Q 2 = 0, we present predictions that are in remarkably good agreement with the existing experimental data both in trend and magnitude.

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Pion form factor in QCD at intermediate momentum transfers

Cited by 147 publications

References 57 publications

Deep inelastic pion electroproduction at threshold

Deep inelastic pion electroproduction at threshold

Perturbative corrections to Λ b → Λ form factors from QCD light-cone sum rules

Publisher's Note: Pion form factor in QCD: From nonlocal condensates to next-to-leading-order analytic perturbation theory [Phys. Rev. D 70, 033014 (2004)]

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