Determination of electron-nucleus collision geometry with forward neutrons

Zheng, Liang; Aschenauer, E. C.; Lee, J. H.

doi:10.1140/epja/i2014-14189-3

Cited by 17 publications

(22 citation statements)

References 46 publications

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“…There one would observe deviations from the scale evolution governed by the physical anomalous dimensions, which will unambiguously quantify the size and relevance of non-linear effects caused by an abundance of gluons with small momentum fractions [65]. A experimentally driven way to study nonlinear effects is studying the ratio of F A 2 =F p 2 and other structure functions as function of A and tagging the centrality of the collision [28]. A particularly strong impact-parameter dependence of the ratio F A 2 =F p 2 in central collisions towards small x and low Q 2 could be a sign of nonlinear effects becoming dominant, as the estimated impact-parameter dependence of nPDFs is there only rather weak [66].…”

Section: Relation To Nonlinear Qcdmentioning

confidence: 99%

Nuclear structure functions at a future electron-ion collider

et al. 2017

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The quantitative knowledge of heavy nuclei's partonic structure is currently limited to rather large values of momentum fraction x-robust experimental constraints below x ∼ 10 −2 at low resolution scale Q 2 are particularly scarce. This is in sharp contrast to the free proton's structure which has been probed in Deep Inelastic Scattering (DIS) measurements down to x ∼ 10 −5 at perturbative resolution scales. The construction of an electron-ion collider (EIC) with a possibility to operate with a wide variety of nuclei, will allow one to explore the low-x region in much greater detail. In the present paper we simulate the extraction of the nuclear structure functions from measurements of inclusive and charm reduced cross sections at an EIC. The potential constraints are studied by analyzing simulated data directly in a next-toleading order global fit of nuclear Parton Distribution Functions based on the recent EPPS16 analysis. A special emphasis is placed on studying the impact an EIC would have on extracting the nuclear gluon parton distribution function, the partonic component most prone to nonlinear effects at low Q 2 . In comparison to the current knowledge, we find that the gluon parton distribution function can be measured at an EIC with significantly reduced uncertainties.

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Section: Relation To Nonlinear Qcdmentioning

confidence: 99%

Nuclear structure functions at a future electron-ion collider

et al. 2017

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“…However, we would still expect good resolution in a sizeable part of the relevant p T region. On the other hand, ballistic neutrons, while perhaps measurable in a Zero Degree Calorimeter (ZDC), can be challenging to separate from evaporation neutrons [18].…”

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confidence: 99%

“…[18]. A potential impact of this centrality selection on single inclusive multiplicities and di-hadron correlations was also discussed.…”

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confidence: 99%

Ballistic Protons in Incoherent Exclusive Vector Meson Production as a Measure of Rare Parton Fluctuations at an Electron-Ion Collider

2015

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We argue that the proton multiplicities measured in Roman pot detectors at an electron ion collider can be used to determine centrality classes in incoherent diffractive scattering. Incoherent diffraction probes the fluctuations in the interaction strengths of multi-parton Fock states in the nuclear wavefunctions. In particular, the saturation scale that characterizes this multi-parton dynamics is significantly larger in central events relative to minimum bias events. As an application, we study the centrality dependence of incoherent diffractive vector meson production. We identify an observable which is simultaneously very sensitive to centrality triggered parton fluctuations and insensitive to details of the model. Introduction Very high multiplicity events in protonproton (p+p) and proton/deuteron-nucleus (p/d+A) collisions at LHC and RHIC have revealed that the structure of such events is more complex and interesting than previously imagined [1][2][3][4]. In particular, interpreting the results of these experiments requires a deeper understanding of event-by-event multi-parton spatial fluctuations in protons and nuclei [5][6][7][8][9]. Incoherent diffraction in deeply inelastic scattering (DIS) of electrons off nuclei (e+A collisions) has been long understood as having the potential to provide insight into event-by-event fluctuations in the spatial structure of nuclei. A significant advantage of e+A collisions relative to p+A collisions is that the former is insensitive to the final state interactions that, in the latter, can complicate the extraction of the spatial parton structure of the proton and the nucleus.

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“…This provides a more stringent upper bound of p ′2 1T ≤ 2.25 GeV 2 . Such events have also been discussed previously in the context of centrality selection in e+A collisions [55]; further precision in the measurement of the process of interest is allowed by installation of neutron detectors [56]. We note that neutron-proton coincidence studies have been performed previously at Jefferson lab-see for instance [57] and references therein.…”

Section: Estimation Of Ratesmentioning

confidence: 54%

Probing short-range nucleon-nucleon interactions with an electron-ion collider

2016

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We derive the cross-section for exclusive vector meson production in high energy deeply inelastic scattering off a deuteron target that disintegrates into a proton and a neutron carrying large relative momentum in the final state. This cross-section can be expressed in terms of a novel gluon Transition Generalized Parton Distribution (T-GPD); the hard scale in the final state makes the T-GPD sensitive to the short distance nucleon-nucleon interaction. We perform a toy model computation of this process in a perturbative framework and discuss the time scales that allow the separation of initial and final state dynamics in the T-GPD. We outline the more general computation based on the factorization suggested by the toy computation: in particular, we discuss the relative role of "point-like" and "geometric" Fock configurations that control the parton dynamics of short range nucleon-nucleon scattering. With the aid of exclusive J/Ψ production data at HERA, as well as elastic nucleon-nucleon cross-sections, we estimate rates for exclusive deuteron photo-disintegration at a future Electron-Ion Collider (EIC). Our results, obtained using conservative estimates of EIC integrated luminosities, suggest that center-of-mass energies s N N ∼ 12 GeV 2 of the neutron-proton subsystem can be accessed. We argue that the high energies of the EIC can address outstanding dynamical questions regarding the short-range quark-gluon structure of nuclear forces by providing clean gluon probes of such "knockout" exclusive reactions in light and heavy nuclei. *

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Determination of electron-nucleus collision geometry with forward neutrons

Cited by 17 publications

References 46 publications

Nuclear structure functions at a future electron-ion collider

Nuclear structure functions at a future electron-ion collider

Ballistic Protons in Incoherent Exclusive Vector Meson Production as a Measure of Rare Parton Fluctuations at an Electron-Ion Collider

Probing short-range nucleon-nucleon interactions with an electron-ion collider

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