The perturbative proton form factor reexamined

Kundu, Bijoy; Li, Hsiang-nan; Samuelsson, Jim; Jain, Pankaj

doi:10.1007/s100529900004

Cited by 28 publications

(31 citation statements)

References 7 publications

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“…The factor 1.14 is adopted because this cut-off choice can result in form factors which vary smoothly with square of momentum transfer in fitting Λ b → Λ c lν process and it reflects the resummation of next-to-leading double log in higher order radiative corrections [23]. Also the β and m q in the heavy baryon wavefunction distribution need to be fixed.…”

Section: Numerical Resultsmentioning

confidence: 99%

Perturbative QCD calculation forΛb→Λγin the standard model

et al. 2006

Phys. Rev. D

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Abstract:We calculate the branching ratio of Λ b → Λγ in the standard model using the PQCD method. The predicted branching ratio B(Λ b → Λγ) is about (4.3 ∼ 8.6) × 10 −8 , with reasonable parameter ranges in the heavy baryon distribution amplitude. This branching ratio is much smaller than those obtained in other hadronic model calculations. Future experimental data can provide important information on applicability of the PQCD method to heavy baryon radiative decay.

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Section: Numerical Resultsmentioning

confidence: 99%

Perturbative QCD calculation forΛb→Λγin the standard model

et al. 2006

Phys. Rev. D

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“…The phenomenological factor 1.14 is adopted according to Ref. [25] to make the whole picture more realistic. Moreover, the values of β and m q in the heavy baryon wave function need to be fixed.…”

Section: Numerical Resultsmentioning

confidence: 99%

Calculation ofBR(B¯0→Λc++p¯)in the perturbative Q

et al. 2007

Phys. Rev. D

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Abstract:We calculate the branching ratio of B 0 → Λ + c p in the PQCD approach. Most previous model calculations obtained branching ratios significantly larger than experimental data. We find that the predicted branching ratio for BR(B 0 → Λ + c p) in the PQCD approach can vary over a range of (2.3 ∼ 5.1) × 10 −5 with the largest uncertainty coming from the parameters in the wave function of Λ c . With the favored values for the parameters in the Λ + c wave function, β = 1 GeV and m q = 0.3 GeV, the branching ratio is about 2.3 × 10 −5 which is satisfactorily consistent with the value measured by experiments.

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“…Here we compute the proton electromagnetic form factor, F 1 , assuming end point domination. There have been several earlier calculations of this form factor in different models [59][60][61][62][63][64][65][66][67][68][69][70][71]. The basic diagram for calculating proton electromagnetic form factors is shown in Fig.…”

Section: 2mentioning

confidence: 99%

Uncovering the scaling laws of hard exclusive hadronic processes in a comprehensive endpoint model

2014

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We show that an endpoint-overlap model can explain the scaling laws observed in exclusive hadronic reactions at large momentum transfer. The model assumes one of the valence quarks carries most of the hadron momentum. Hadron form factors and fixed-angle scattering are related directly to the quark wave function, which can be directly extracted from experimental data. A universal linear endpoint behavior explains the proton electromagnetic form factor, proton-proton fixed-angle scattering, and the t-dependence of proton-proton scattering at large s >> t. Endpoint constituent counting rules relate the number of quarks in a hadron to the power-law behavior. All proton reactions surveyed are consistent with three quarks participating. The model is applicable at laboratory energies and does not need assumptions of asymptotically high energy regime. A rich phenomenology of lepton-hadron scattering and hadron-hadron scattering processes is found in remarkably simple relationships between diverse processes. Experimental regularitiesThe experimental study of differential cross sections of hard exclusive hadronic reactions at high energy reveals a remarkable pattern: They are described by power laws [1][2][3]. A model explanation exists [4][5][6][7], yet it is not satisfactory [8] at the energies of experimental measurements. We are driven to find a consistent explanation of experimental regularities by re-examining all the facts from a fresh point of view."Hard" reactions are those which depend on a single large scale Q 2 > GeV 2 , or several large scales with a fixed ratio. It is remarkable that the proton electromagnetic form factor a e-mail: sumeetkd@iitk.ac.in b e-mail: pkjain@iitk.ac.in c e-mail: ralston@ku.edu F 1 (Q 2 ) agrees well with a decreasing power of Q 2 for Q 2 5 GeV 2 [9]. For large momentum transfer, it is remarkable that pp → pp fixed-angle cross section dσ/dt agrees well with a decreasing power of Q 2 ∼ s [10], where √ s is the center of mass energy. There are many other examples.We have re-evaluated the phenomenology of power-law dependence or "scaling laws" for exclusive reactions. Due to history, the most simple and plausible explanation failed to be developed. The model appears in the literature as the Feynman process, also known as the Drell-Yan model, also known as the endpoint-overlap model [11][12][13]. There is much to be learned and much that is new when the model is objectively explored. The endpoint-overlap modelBefore engaging the technical analysis, a brief synopsis of history is appropriate. It is fair to observe that relatively few papers in recent years have supported the short-distance model that dominated attention earlier. How and why did consideration of soft processes in hard scattering take so long to develop? In their evaluation of the endpoint region, Brodsky and Mueller [14] wrote that "its contribution depends sensitively on the hadronic wave functions". The discussion discovered no actual fault in the endpoint contribution. Instead of finding a flaw, the section end...

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The perturbative proton form factor reexamined

Cited by 28 publications

References 7 publications

Perturbative QCD calculation forΛb→Λγin the standard model

Perturbative QCD calculation forΛb→Λγin the standard model

Calculation ofBR(B¯0→Λc++p¯)in the perturbative Q

Uncovering the scaling laws of hard exclusive hadronic processes in a comprehensive endpoint model

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