Electroproduction of ?+ n, ?- p andK + ?,K + 2211; 0 final states above the resonance region

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

doi:10.1007/bf01443698

Cited by 173 publications

(203 citation statements)

References 67 publications

Supporting

Mentioning

187

Contrasting

Order By: Relevance

“…tive events coming from the exclusive reactions e + p → e ′ + π + + n and e + n → e ′ + π − + p. This required a model for the cross section of exclusive pion electroproduction that is valid for a large range of W (from the resonance region to W ≈ 2.5 GeV) at relatively large Q 2 . The model used in this analysis started with the parameterization of exclusive π + and π − production cross section data from [77] While the starting parameterization is appropriate for describing exclusive pion production above the resonance region, it does rather poorly for values of W significantly smaller than 2 GeV. Since no existing model or parameterization describes exclusive pion production both in the resonance region and at large W , we chose to adjust our starting model by-hand to give good agreement with the MAID model [80] of pion electroproduction in the resonance region.…”

Section: A Background Subtraction and Correctionsmentioning

confidence: 99%

Semi-inclusive charged-pion electroproduction off protons and deuterons: Cross sections, ratios, and access to the quark-parton model at low energies

Asaturyan¹,

Ent²,

Mkrtchyan³

et al. 2012

Phys. Rev. C

View full text Add to dashboard Cite

A large set of cross sections for semi-inclusive electroproduction of charged pions (π ± ) from both proton and deuteron targets was measured. The data are in the deep-inelastic scattering region with invariant mass squared W 2 > 4 GeV 2 (up to ≈ 7 GeV 2 ) and range in four-momentum transfer squared 2 < Q 2 < 4 (GeV/c) 2 , and cover a range in the Bjorken scaling variable 0.2 < x < 0.6. The fractional energy of the pions spans a range 0.3 < z < 1, with small transverse momenta with respect to the virtual-photon direction, P 2 t < 0.2 (GeV/c) 2 . The invariant mass that goes undetected, Mx or W ′ , is in the nucleon resonance region, W ′ < 2 GeV. The new data conclusively show the onset of quark-hadron duality in this process, and the relation of this phenomenon to the high-energy factorization ansatz of electron-quark scattering and subsequent quark → pion production mechanisms. The x, z and P 2 t dependences of several ratios (the ratios of favored-unfavored fragmentation functions, charged pion ratios, deuteron-hydrogen and aluminum-deuteron ratios for π + and π − ) have been studied. The ratios are found to be in good agreement with expectations based upon a high-energy quark-parton model description. We find the azimuthal dependences to be small, as compared to exclusive pion electroproduction, and consistent with theoretical expectations based on tree-level factorization in terms of transverse-momentum-dependent parton distribution and fragmentation functions. In the context of a simple model, the initial transverse momenta of d quarks are found to be slightly smaller than for u quarks, while the transverse momentum width of the favored fragmentation function is about the same as for the unfavored one, and both fragmentation widths are larger than the quark widths.

show abstract

Section: A Background Subtraction and Correctionsmentioning

confidence: 99%

Semi-inclusive charged-pion electroproduction off protons and deuterons: Cross sections, ratios, and access to the quark-parton model at low energies

Asaturyan¹,

Ent²,

Mkrtchyan³

et al. 2012

Phys. Rev. C

View full text Add to dashboard Cite

show abstract

“…There have been numerous experimental [1][2][3][4][5][6][7] and theoretical studies [8][9][10][11][12] of the EM form factors of the light pseudoscalar meson (π ana K). However, duing to the experiments are more difficult, the EM form factors of the light vector meson (ρ and K * ) have fewer investigations than their pseudoscalar counterparts [13,14], even though they could provide much information about the bound-state dynamics.…”

Section: Introductionmentioning

confidence: 99%

Charge radii of light and heavy mesons

Hwang

2002

Eur. Phys. J. C

View full text Add to dashboard Cite

We calculate the electromagnetic (EM) form fators of the pseudoscalar mesons in the light-front framework. Specially, these form factors are extracted from the relevant matrix elements directly, instead of choosing the Breit frame. The results show that the charge radius of the meson are related to both the first and second longitudinal momentum square derivative of the momentum distribution function. The static properties of the EM form factors and the heavy quark symmetry of the charge radii are checked analytically when we take the heavy quark limit. In addition, we use the Gaussia-type wave function to obtain the numerical results.

show abstract

“…The W -dependence was taken as (W 2 − M 2 N ) −2 , where M N is the struck nucleon mass, based on analyses of experimental data from Refs. [6,27]. For the parts depending on Q 2 and t, phenomenological forms were used and the parameters were fitted.…”

Section: Determination Of Separated Structure Functionsmentioning

confidence: 99%

“…Such physics backgrounds may be expected to be larger at higher −t (due to the drop-off of the pion pole contribution) or non-forward kinematics (due to angular momentum conservation) [5]. Because previous data are unseparated [6], no firm conclusions about possible deviations of R L from unity were possible. One can also use such hard exclusive processes to investigate the range of applicability of QCD factorization and scaling theorems.…”

Section: Introductionmentioning

confidence: 98%

Separated response functions in exclusive, forwardπ±electroproduction on deuterium

Huber¹,

Blok²,

Butuceanu³

et al. 2015

Phys. Rev. C

View full text Add to dashboard Cite

Background: Measurements of forward exclusive meson production at different squared four-momenta of the exchanged virtual photon, Q 2 , and at different four-momentum transfer, t, can be used to probe QCD's transition from meson-nucleon degrees of freedom at long distances to quark-gluon degrees of freedom at short scales. Ratios of separated response functions in π − and π + electroproduction are particularly informative. The ratio for transverse photons may allow this transition to be more easily observed, while the ratio for longitudinal photons provides a crucial verification of the assumed pole dominance, needed for reliable extraction of the pion form factor from electroproduction data.Purpose: Perform the first complete separation of the four unpolarized electromagnetic structure functions L/T /LT /T T in forward, exclusive π ± electroproduction on deuterium above the dominant resonances.Method: Data were acquired with 2.6-5.2 GeV electron beams and the HMS+SOS spectrometers in Jefferson Lab Hall C, at central Q 2 values of 0.6, 1.0, 1.6 GeV 2 at W =1.95 GeV, and Q 2 = 2.45 GeV 2 at W =2.22 GeV. There was significant coverage in φ and ǫ, which allowed separation of σL,T,LT,T T . 2Results: σL shows a clear signature of the pion pole, with a sharp rise at small −t. In contrast, σT is much flatter versus t. The longitudinal/transverse ratios evolve with Q 2 and t, and at the highest Q 2 = 2.45 GeV 2 show a slight enhancement for π − production compared to π + . The π − /π + ratio for transverse photons exhibits only a small Q 2 -dependence, following a nearly universal curve with t, with a steep transition to a value of about 0.25, consistent with s-channel quark knockout. The σT T /σT ratio also drops rapidly with Q 2 , qualitatively consistent with s-channel helicity conservation. The π − /π + ratio for longitudinal photons indicates a small isoscalar contamination at W =1.95 GeV, consistent with what was observed in our earlier determination of the pion form factor at these kinematics. Conclusions: The separated cross sections are compared to a variety of theoretical models, which generally describe σL but have varying success with σT . Further theoretical input is required to provide a more profound insight into the relevant reaction mechanisms for longitudinal and transverse photons, such as whether the observed transverse ratio is indeed due to a transition from pion to quark knockout mechanisms, and provide useful information regarding the twist-3 transversity generalized parton distribution, HT .

show abstract

Electroproduction of ?+ n, ?- p andK + ?,K + 2211; 0 final states above the resonance region

Cited by 173 publications

References 67 publications

Semi-inclusive charged-pion electroproduction off protons and deuterons: Cross sections, ratios, and access to the quark-parton model at low energies

Semi-inclusive charged-pion electroproduction off protons and deuterons: Cross sections, ratios, and access to the quark-parton model at low energies

Charge radii of light and heavy mesons

Separated response functions in exclusive, forwardπ±electroproduction on deuterium

Contact Info

Product

Resources

About