Coherence effects in diffractive electroproduction of mesons from nuclei

Renk, Thorsten; Piller, G.; Weise, W.

doi:10.1016/s0375-9474(00)00700-4

Cited by 10 publications

(12 citation statements)

References 25 publications

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“…Indeed, if the coherence length varies from long to short compared to the nuclear size the nuclear transparency rises because the length of the path in 4 Note that Eq. (52) and its Glauber model analog in [16] include all coherent multiple scattering terms, contrary to a statement made in [55]. 5 This process has a definite advantage compared to quasielastic electron scattering (e,e'p) suggested in [58,59] as a probe for CT.…”

Section: Data For Incoherent Production: Ct or Coherence?mentioning

confidence: 88%

Color transparency versus quantum coherence in electroproduction of vector mesons off nuclei

et al. 2002

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So far no theoretical tool for the comprehensive description of exclusive electroproduction of vector mesons off nuclei at medium energies has been developed. We suggest a light-cone QCD formalism which is valid at any energy and incorporates formation effects (color transparency), the coherence length and the gluon shadowing. At medium energies color transparency (CT) and the onset of coherence length (CL) effects are not easily separated. Indeed, although nuclear transparency measured by the HERMES experiment rises with Q 2 , it agrees with predictions of the vector dominance model (VDM) without any CT effects. Our new results and observations are: (i) the good agreement with the VDM found earlier is accidental and related to the specific correlation between Q 2 and CL for HERMES kinematics; (ii) CT effects are much larger than have been estimated earlier within the two channel approximation. They are even stronger at low than at high energies and can be easily identified by HERMES or at JLab; (iii) gluon shadowing which is important at high energies is calculated and included; (iv) our parameter-free calculations explain well available data for variation of nuclear transparency with virtuality and energy of the photon; (v) predictions for electroproduction of ρ and φ are provided for future measurements at HERMES and JLab.

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Section: Data For Incoherent Production: Ct or Coherence?mentioning

confidence: 88%

Color transparency versus quantum coherence in electroproduction of vector mesons off nuclei

et al. 2002

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“…There, different diffractive slope parameters and relativistic (non relativistic) Breit-Wigner mass distributions were used as an input parameters. Finally, corrections («15%) were applied to the ratios due to the "Pauli blocking" effect [20,21] for incoherent scattering. The coherent (incoherent) nuclear transparency is defined as…”

Section: Methodsmentioning

confidence: 99%

Nuclear Transparency in Exclusive ρ0 Production at HERMES

Lorenzon¹

2004

AIP Conference Proceedings

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Exclusive coherent and incoherent electroproduction of the p° meson from 1 H and 14 N targets has been studied at the HERMES experiment as a function of coherence length (l c), corresponding to the lifetime of hadronic fluctuations of the virtual photon, and squared fourmomentum of the virtual photon (-<2 2). The ratio of I4 N to *H cross sections per nucleon, called nuclear transparency, was found to increase (decrease) with increasing coherence length for coherent (incoherent) p° electroproduction. For fixed coherence length, arise of nuclear transparency with Q 2 is observed for both coherent and incoherent p° production, which is in agreement with theoretical calculations of color transparency.

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“…The photon virtuality was 0.4 GeV 2 < Q 2 < 5 GeV 2 which is much larger than the Q 2 < 1/R 2 in AA collisions. A theoretical discussion is given in [194] where a systematic multiple scattering formalism is developed for vector meson electroproduction from nuclei. Also formation-, propagation-, and hadronization-scales for quarkgluon fluctuations of the virtual high-energy photon are considered.…”

Section: Incoherent Production Of Vector Mesonsmentioning

confidence: 99%

Coherent γγ and γA interactions in very peripheral collisions at relativistic ion colliders

et al. 2002

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Due to coherence, there are strong electromagnetic fields of short duration in very peripheral collisions. They give rise to photon-photon and photon-nucleus collisions with a high flux up to an invariant mass region hitherto unexplored experimentally. After a general survey of the field equivalent photon numbers and photon-photon luminosities, especially for relativistic heavy ion collisions, are discussed. Special care needs to be taken to include the effects of the strong interaction and nuclear size in this case. Photon-photon and photon-hadron physics at various invariant mass scales are then discussed. The maximum equivalent photon energy in the lab-system (collider frame) are typically of the order of 3 GeV for RHIC and 100 GeV for LHC. Diffractive processes are an important background process. Lepton-pair, especially electron-positron pair production is copious. Due to the strong fields there will be new phenomena, like multiple e + e − pair production. The experimental techniques to select γγ-processes are finally discussed together with important background processes.

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Coherence effects in diffractive electroproduction of mesons from nuclei

Cited by 10 publications

References 25 publications

Color transparency versus quantum coherence in electroproduction of vector mesons off nuclei

Color transparency versus quantum coherence in electroproduction of vector mesons off nuclei

Nuclear Transparency in Exclusive ρ0 Production at HERMES

Coherent γγ and γA interactions in very peripheral collisions at relativistic ion colliders

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