Probing the mesonic structure of the nucleon by means of exclusive quasielastic pion knockout in (e, e′π) reactions at high energies

Neudatchin, V. G.; Sviridova, L. L.; Yudin, N. P.

doi:10.1134/1.1409501

Cited by 7 publications

(45 citation statements)

References 42 publications

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“…We define the T -matrix amplitude for the process N + K ± → Θ + as [19] (by analogy with the Lippmann-Schwinger equation [20]) where, obviously, Θ + |N, K ± = N, K ± |Θ + * . In the nucleon rest frame (laboratory frame),…”

Section: Electroproduction Of Antidecuplet States By Longitudinal Phomentioning

confidence: 99%

“…This amplitude corresponds to the process where the quasielastic knockout of a kaon from a polarized QCD vacuum of the nucleon involved is followed by the capture of the antiparticle corresponding to this kaon by the nucleon and the formation of a pentaquark as a spectator baryon (pole Z diagram [19,20]). On the basis of crossing symmetry [28], the amplitude in (22) also takes into account the contribution of the direct meson-in-flight diagram (Fig.…”

Section: Electroproduction Of Antidecuplet States By Longitudinal Phomentioning

confidence: 99%

“…There are reasons to believe that, in the case of a longitudinal photon, it is precisely the virtual-kaon amplitude that is dominant in the process being considered [19,20]. That the kaon amplitude is dominant, for example, in relation to the amplitude for the process in which the knockout of a K * meson is followed by its intrinsic-spin-flip charge exchange into a kaon is due largely to the proximity of the virtual momentum |k| to |k| min in the region of quasielastic kinematics (see below) rather than to the presumed smallness of the constant of this charge exchange and to a smaller value of the spectroscopic factor for the process involving a virtual decay to K * .…”

Section: Electroproduction Of Antidecuplet States By Longitudinal Phomentioning

confidence: 99%

“…In this analysis, we employ experience previously gained by our group in developing (on the basis of the quark microscopic approach) the theory of quasielastic meson knockout by electrons in processes belonging to the N (e, e π)N or N (e, e K)Λ type and featuring longitudinal and transverse virtual photons [19,20] and also rely on a quark microscopic description of q 4q states. Owing to the simplicity of the mechanism of such reactions, a comparison of differential cross sections for processes involving the knockout of different mesons makes it possible to determine the structure of B states, including wave-function components corresponding to hidden strangeness (ss), and to find, for example, the parity of a B state from the shape and magnitude of the momentum distribution in B → N + M virtual decays.…”

Section: Introductionmentioning

confidence: 99%

“…A normalization of momentum distributions provides directly the spectroscopic factor [19,20], which is an important structural feature of the corresponding process. In the case of the pentaquark state of the spectator baryon, the spectroscopic factor is determined by the projection of the pentaquark-state wave function onto the meson-nucleon channel.…”

Section: Introductionmentioning

confidence: 99%

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10.1007/s11450-008-3013-4

2010

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The possibility of studying q 4q exotic baryon states by means of N (e, e M )B reactions proceeding via an extremely simple mechanism and involving the quasielastic knockout of various mesons from a nucleon by electrons of energy in the few-GeV region is considered as a development of the previous investigations of our group. A quark microscopic formalism based on the cluster model of q 4q states, which makes it possible to determine momentum distributions of mesons in various channels of B → N + M virtual decays (in principle, these distributions can be compared with experimental data), is expounded by considering the example of the pentaquark (B = Θ + ). The decay widths of the q 4q baryon states being discussed are governed by the degree of separation of quark clusters (this is a parameter of the model used). The electroproduction cross sections prove to be small because of kinematical constraints requiring that physically admissible values of the momentum |k| of the virtual meson M lie in the region where relevant amplitudes are suppressed substantially by form factors in pentaquark vertices. In particular, N (e, e π ± )B reactions involving pion knockout furnish direct information about nonstrange components of baryon B; however, the expected cross sections for such reactions are an order of magnitude smaller than their counterparts for analogous reactions leading to the production of a pentaquark Θ + . Because of the smallness of the electroproduction cross sections, it is reasonable to consider the production of a pentaquark and other q 4q exotic states in reactions characterized by quasielastic kinematics and initiated by pions of energy in the range between about 1 and 5 GeV and in similar stripping and pickup nuclear reactions.

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Section: Electroproduction Of Antidecuplet States By Longitudinal Phomentioning

confidence: 99%

Section: Electroproduction Of Antidecuplet States By Longitudinal Phomentioning

confidence: 99%

Section: Electroproduction Of Antidecuplet States By Longitudinal Phomentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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10.1007/s11450-008-3013-4

2010

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10.1007/s11450-008-3016-1

2010

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It is shown that, under kinematical conditions of quasielastic knockout, the differential cross section for the exclusive process p(e, e π + )n induced by longitudinal virtual photons γ * L changes its physical nature as the recoil momentum |k| of the spectator nucleon grows from values in the range |k| ∼ 0.1-0.4 GeV/c, which are typical in studying the pion cloud of the nucleon, to values around |k| ∼ 1 GeV/c. Calculations within the 3 P 0 quark microscopic model reveal that the amplitudes for the deexcitation of vector and pseudovector mesons via the processes ρ + + γ * L → π + and b + 1 + γ * L → π + become dominant here. Concurrently, the effective momentum distributions develop a substantial angular anisotropy of about 50% with respect to the angle between the momentum of the photon γ * L and the recoil momentum of the spectator nucleon, the longitudinal differential cross sections undergoing respective changes. In this region, the energy of knock-on pions is expected to be about 5 GeV under conditions of quasilastic kinematics.

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Quasi-elastic knockout of pions and kaons from nucleons by high-energy electrons and quark microscopy of “soft” meson degrees of freedom in the nucleon

Neudatchin¹,

Obukhovsky²,

Sviridova³

et al. 2004

Nuclear Physics A

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Electro-production of pions and kaons at the kinematics of quasi-elastic knockout (which is well known in the physics of atomic nucleus and corresponds to the t-pole diagram) is proposed for obtaining their momentum distribution (MD) in various channels of virtual decay N → B +π, B = N , ∆, N * , N * * , and N → Y +K, Y = Λ, Σ. It is a powerful tool for investigation of a quark microscopic picture of the meson cloud in the nucleon. A model of scalar qq ( 3 P 0 ) fluctuation in the non-trivial QCD vacuum is used to calculate pion and kaon momentum distributions (MD) in these channels. 1 In the constituent quark model the pion charge radius includes contributions both quarks and the ρ-meson pole (the vector meson dominance model): [< r 2 π > ch ] 1/2 = [3b 2 π /4 + 6/m 2 ρ ] 1/2 ≃ 0.68 fm.

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Probing the mesonic structure of the nucleon by means of exclusive quasielastic pion knockout in (e, e′π) reactions at high energies

Cited by 7 publications

References 42 publications

10.1007/s11450-008-3013-4

10.1007/s11450-008-3013-4

10.1007/s11450-008-3016-1

Quasi-elastic knockout of pions and kaons from nucleons by high-energy electrons and quark microscopy of “soft” meson degrees of freedom in the nucleon

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