Exclusive diffractive processes in electron-ion collisions

Toll, T.; Ullrich, T.

doi:10.1103/physrevc.87.024913

Cited by 116 publications

(132 citation statements)

References 39 publications

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“…At momentum scales corresponding to the nucleon size |t| ∼ 1/R 2 p the diffractive cross section is almost purely incoherent. The t-distribution in coherent diffractive production off nucleus gives rise to a dip-type structure for both saturation and non-saturation models, while in the case of incoherent production at small |t|, both saturation and non-saturation models do not lead to dips [83,84]. This is in drastic contrast to the diffractive production off proton where only saturation models lead to dip-type structure in the t-distribution at values of |t| that can be experimentally accessible.…”

Section: Discussioncontrasting

confidence: 46%

“…Therefore, the t-distribution of diffractive vector mesons would provide the most important information on the relevance of saturation dynamics. Besides, the impact parameter distribution of gluons in protons and nuclei (a natural extension of our work that can be explored in electron-nucleus colliders [3,4], see also [81][82][83][84]) is a crucial ingredient for a detailed characterisation of the initial conditions in heavy ion collisions. Note that the effects of fluctuations and correlations on the proton are not incorporated into our formulation.…”

Section: Discussionmentioning

confidence: 99%

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Exclusive vector meson production at high energies and gluon saturation

Rezaeian

2014

Proceedings of XXII. International Workshop on Deep-Inelastic Scattering and Related Subjects — PoS(DIS2014)

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We systematically study exclusive diffractive (photo) production of vector mesons (J/ψ, ψ(2s), φ and ρ) off protons in high-energy collisions and investigate whether the production is a sensitive probe of gluon saturation. We confront saturation-based results for diffractive ψ(2s) and ρ production at HERA and J/ψ photoproduction with all available data including recent ones from HERA, ALICE and LHCb, finding good agreement. In particular, we show that the t-distribution of differential cross sections of photoproduction of vector mesons offers a unique opportunity to discriminate among saturation and non-saturation models. This is due to the emergence of a pronounced dip (or multiple dips) in the t-distribution of diffractive photoproduction of vector mesons at relatively large, but potentially accessible |t| that can be traced back to the unitarity features of colour dipole amplitude in the saturation regime. We show that in saturation models the dips in t-distribution recede towards lower |t| with decreasing mass of the vector meson, increasing energy or decreasing Bjorken-x, and decreasing virtuality Q. We provide various predictions for exclusive (photo) production of different vector mesons including the ratio of ψ(2s)/J/ψ at HERA, the LHC, and future colliders.

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Section: Discussioncontrasting

confidence: 46%

Section: Discussionmentioning

confidence: 99%

Exclusive vector meson production at high energies and gluon saturation

Rezaeian

2014

Proceedings of XXII. International Workshop on Deep-Inelastic Scattering and Related Subjects — PoS(DIS2014)

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“…Thus, regardless of the dynamical mechanism of nuclear shadowing, large nuclear gluon shadowing leads to the modification of the t distribution of J/ψ photoproduction in ion UPCs. At the same time, in the implementations of the color dipole framework, where coherent photoproduction of J/ψ on nuclei proceeds via multiple rescattering of quark-antiquark dipoles [13,44,45], the shadowing correction is not large since the average dipole-nucleon cross section is determined by the small size of J/ψ. As a result, the modification of the t distribution of J/ψ photoproduction on nuclei compared to F 2 A (t) is smaller than predicted in our analysis.…”

Section: Resultsmentioning

confidence: 99%

Accessing transverse nucleon and gluon distributions in heavy nuclei using coherent vector meson photoproduction at high energies in ion ultraperipheral collisions

2017

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Using the theoretical approaches describing well the available data on t-integrated coherent photoproduction of light and heavy vector mesons in Pb-Pb UPCs at the LHC in Run 1, we calculate the momentum transfer distributions for this process for ρ and J/ψ vector mesons in the kinematics of Run 2 at the LHC. We demonstrate that nuclear shadowing not only suppresses the absolute value of the cross sections, but also shifts the momentum transfer distributions toward smaller values of the momentum transfer |t|. This result can be interpreted as a broadening in the impact parameter space of the effective nucleon density in nuclei by 14% in the case of ρ and the nuclear gluon distribution by 5 − 11% in the case of J/ψ.

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“…This is shown for both the J/ψ and the φ vector mesons. Both of these distributions were generated using the SARTRE MC event generator which has recently been developed for diffractive physics in e+A collisions [5]. This shows that in the case of the J/ψ, then there is very little difference between the PANIC14distributions for the saturated and unsaturated case.…”

Section: Diffraction In E + a Collisionsmentioning

confidence: 99%

Measuring the gluon distribution in nuclei at an electron–ion collider

Lamont

2014

Nuclear Physics A

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Despite the successes of the HERA accelerator, where much information was gained on the structure of the nucleon, data on the structure of the nucleus at moderate-to-small x remains elusive, as only fixed-target high-x data currently exist. The small-x region, however, is of great interest. The nucleon structure in this region is dominated by gluons which show a rapid rise with decreasing x. At low-x, this growth must be tamed and the gluon distribution will be saturated. However, only tantalising hints of this have been observed so far. Therefore, the construction of an Electron-Ion Collider (EIC), colliding polarised electrons with polarised protons and also a wide variety of nuclei, will allow an exploration of the region of small-x in great detail, answering questions on both the spatial and momentum distributions of gluons and sea quarks in nuclei. In particular, the saturation region is more accessible in nuclei due to the amplification of the saturation scale with nuclear size (QS ∝ A 1/3 ). In this paper I present the current status of measuring the gluon distribution in nuclei in e+A collisions at an EIC.

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Exclusive diffractive processes in electron-ion collisions

Cited by 116 publications

References 39 publications

Exclusive vector meson production at high energies and gluon saturation

Exclusive vector meson production at high energies and gluon saturation

Accessing transverse nucleon and gluon distributions in heavy nuclei using coherent vector meson photoproduction at high energies in ion ultraperipheral collisions

Measuring the gluon distribution in nuclei at an electron–ion collider

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