Large angle neutron-proton elastic scattering from 5 to 12 GeV/c

Stone, James L.; Chanowski, J. P.; Gustafson, H. R.; Longo, Michael J.; Gray, S. W.

doi:10.1016/0550-3213(78)90446-7

Cited by 16 publications

(3 citation statements)

References 49 publications

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“…Agreement with experiment [5,10,[86][87][88][89][90][91][92][93][94]98,99] [103], we conjecture that saddle point interpolation between the endpoint model and the S D model will be the dominant asymptotic amplitude. This is because the Sudakov suppression of one fast quark is less severe than the three fast quarks of the I S model.…”

Section: General Featuressupporting

confidence: 73%

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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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Section: General Featuressupporting

confidence: 73%

“…In this section we find that the experimentally observed power laws of hadron-hadron exclusive reactions [5,10,[80][81][82][83][84][85][86][87][88][89][90][91][92][93][94][95] are explained by the endpoint-overlap model. Unlike the S D model, no approximations of an asymptotic character are needed.…”

Section: Hadron-hadron Exclusive Reactionsmentioning

confidence: 99%

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

2014

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“…Data are from Refs. [47,48] and the curves correspond to the HRM model fits used to calculate predictions for Σ.…”

Section: B2 Hard-rescattering Mechanism (Hrm)mentioning

confidence: 99%

Determination of the Beam-Spin Asymmetry of Deuteron Photodisintegration in the Energy Region $E_γ=1.1-2.3$ GeV

Zachariou,

Ilieva,

Ivanov

et al. 2015

Preprint

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The beam-spin asymmetry, Σ, for the reaction γd → pn has been measured using the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility (JLab) for six photon-energy bins between 1.1 and 2.3 GeV, and proton angles in the center-of-mass frame, θc.m., between 25 • and 160 • . These are the first measurements of beam-spin asymmetries at θc.m. = 90 • for photon-beam energies above 1.6 GeV, and the first measurements for angles other than θc.m. = 90 • . The angular and energy dependence of Σ is expected to aid in the development of QCD-based models to understand the mechanisms of deuteron photodisintegration in the transition region between hadronic and partonic degrees of freedom, where both effective field theories and perturbative QCD cannot make reliable predictions.

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