Separation of σL and σU in π+-electroproduction above the resonance region

Brauel, P.; Canzler, T.; Cords, D.; Felst, R.; Grindhammer, G.; Helm, M.; Kollmann, W.-D.; Krehbiel, H.; Schädlich, M.

doi:10.1016/0370-2693(77)90656-6

Cited by 51 publications

(73 citation statements)

References 11 publications

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“…This means that there is a large gap to be filled in our understanding, extending to relatively high Q 2 values [17]. For Q 2 of a few GeV 2 an indirect experimental method must be used to determine F π with scattering of electrons from the pion cloud around a proton [18][19][20]. The most recent results from Jefferson Lab [21][22][23][24][25] have reached Q 2 = 2.45 GeV 2 but extension to 6 GeV 2 is foreseen [1], starting in 2018, as a key experiment (E12-06-101) for the 12 GeV upgrade.…”

Section: Introductionmentioning

confidence: 99%

Pseudoscalar meson electromagnetic form factor at high Q2 from full lattice QCD

et al. 2017

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We give an accurate determination of the vector (electromagnetic) form factor, F (Q 2 ), for a light pseudoscalar meson up to squared momentum transfer Q 2 values of 6 GeV 2 for the first time from full lattice QCD, including u, d, s and c quarks in the sea at multiple values of the lattice spacing. Our results show good control of lattice discretisation and sea quark mass effects. We study a pseudoscalar meson made of valence s quarks but the qualitative picture obtained applies also to the π meson, relevant to upcoming experiments at Jefferson Lab. We find that Q 2 F (Q 2 ) becomes flat in the region between Q 2 of 2 GeV 2 and 6 GeV 2 , with a value well above that of the asymptotic perturbative QCD expectation, but well below that of the vector-meson dominance pole form appropriate to low Q 2 values. Our calculations show that we can reach higher Q 2 values in future to shed further light on where the perturbative QCD result emerges.

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Section: Introductionmentioning

confidence: 99%

Pseudoscalar meson electromagnetic form factor at high Q2 from full lattice QCD

et al. 2017

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“…Experimental values of F have previously been determined at CEA and Cornell [4], DESY [5,6], and recently at Jefferson Lab [7]. Most of the high Q 2 data have come from experiments at Cornell covering a range of values in Q 2 between 0.28 and 9:77 GeV 2 .…”

mentioning

confidence: 99%

Determination of the Pion Charge Form Factor atQ2=1.60and2.45 (GeV/c)<

Horn¹,

Aniol²,

Arrington³

et al. 2006

Phys. Rev. Lett.

259

164

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The 1 H e; e 0 n cross section was measured at four-momentum transfers of Q 2 1:60 and 2:45 GeV 2 at an invariant mass of the photon nucleon system of W 2:22 GeV. The charged pion form factor (F ) was extracted from the data by comparing the separated longitudinal pion electroproduction cross section to a Regge model prediction in which F is a free parameter. The results indicate that the pion form factor deviates from the charge-radius constrained monopole form at these values of Q 2 by one sigma, but is still far from its perturbative quantum chromodynamics prediction. DOI: 10.1103/PhysRevLett.97.192001 PACS numbers: 14.40.Aq, 11.55.Jy, 13.40.Gp, 25.30.Rw A fundamental challenge in nuclear physics is the description of hadrons in terms of the constituents of the underlying theory of strong interactions, quarks, and gluons. Properties such as the total charge and magnetic moments are well described in a constituent quark framework, which effectively takes into account quark-gluon interactions. However, charge and current distributions, which are more sensitive to the underlying dynamic processes, are not well described.Hadronic form factors provide important information about hadronic structure. The coupling of a virtual photon to structureless particles is completely determined by their charge and magnetic moments. However, for composite particles one must account for the internal structure, which is accomplished by momentum transfer dependent functions. Examples of these functions are the electromagnetic form factors, which describe the distribution of charge and current.One of the simplest hadronic systems available for study is the pion, whose valence structure is a bound state of a quark and an antiquark. The electromagnetic structure of a spinless particle such as the pion is parametrized by a single form factor. Asymptotically, the pion charge form factor, F , is given in perturbative quantum chromodynamics (pQCD) [1]:

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“…Several charged pion electroproduction experiments were designed to extract pion form factor (for example [12,13] for old experiments, and [14,15] for a very recent experiment).…”

Section: Hadron Form Factors In Pion Electroproductionmentioning

confidence: 99%

“…Gutbrod and Kramer allow in their model the nucleon form factor to be different from the on-shell nucleon form factor. Brauel et al [12] and Ackermann et al [13] use this model to extract the pion from factor from separated longitudinal cross section at Q 2 = 0.70 GeV 2 , W = 2.19 GeV, |t| < 0.28 GeV 2 and Q 2 = 0.35 GeV 2 , W = 2.10 GeV, |t| < 0.05 GeV 2 respectively.…”

Section: Hadron Form Factors In Pion Electroproductionmentioning

confidence: 99%

“…1.4), the amplitude of the [15]. Charged pion form factor measurements from [12,13] (black markers), [10,11] (green markers), and [14,15] (yellow and red markers). These measurements are in reasonable agreement with non-pertubative models (blue and red curve), but are in complete disagreement with perturbative models (magenta and black curves).…”

Section: Principle and Formalism Of Regge Phenomenologymentioning

confidence: 99%

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Electroproduction of neutral pions in the Hall A at the Jefferson Laboratory; Electroproduction de pions neutres dans le Hall A au Jefferson Laboratory

Fuchey

2010

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Separation of σL and σU in π+-electroproduction above the resonance region

Cited by 51 publications

References 11 publications

Pseudoscalar meson electromagnetic form factor at high Q2 from full lattice QCD

Pseudoscalar meson electromagnetic form factor at high Q2 from full lattice QCD

Determination of the Pion Charge Form Factor atQ2=1.60and2.45 (GeV/c)<

Electroproduction of neutral pions in the Hall A at the Jefferson Laboratory; Electroproduction de pions neutres dans le Hall A au Jefferson Laboratory

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