Fading out of J/ψ color transparency in high energy heavy ion peripheral collisions

Frankfurt, L.; Strikman, M.; Zhalov, M.

doi:10.1016/s0370-2693(02)02154-8

Cited by 52 publications

(69 citation statements)

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“…Effects of gluon shadowing are investigated and potentials for constraining nuclear gluon modifications are discussed. On the theory front it has been extensively studied at various energies and for different collision systems (see for instance [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]). Diverse approaches ranging from models based on perturbative Quantum Chromodynamics (pQCD) to Color Dipole models and k T factorization have been used to study coherent and incoherent photoproduction of heavy mesons.…”

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confidence: 99%

Coherent photoproduction ofψandΥmesons in ultraperipheralpPb and PbPb collisions at the CERN Large Hadron Collider at
Adeluyi
¹
,
Nguyen
²

2013
Phys. Rev. C
23
1
20
0
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Exclusive photoproduction of vector mesons in the perturbative two-gluon exchange formalism depends significantly on nucleon and nuclear gluon distributions. In the present study we calculate total cross sections and rapidity distributions of J/ψ(1s), ψ(2s), Υ(1s), Υ(2s), and Υ(3s) in ultraperipheral proton-lead (pPb) and lead-lead (PbPb) collisions at the CERN Large Hadron Collider (LHC) at √ s N N = 5 TeV and √ s N N = 2.76 TeV respectively. Effects of gluon shadowing are investigated and potentials for constraining nuclear gluon modifications are discussed. On the theory front it has been extensively studied at various energies and for different collision systems (see for instance [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]). Diverse approaches ranging from models based on perturbative Quantum Chromodynamics (pQCD) to Color Dipole models and k T factorization have been used to study coherent and incoherent photoproduction of heavy mesons. The characteristics of some of the currently employed models is discussed in [1].In previous works [6][7][8] we have considered coherent photoproduction of J/ψ(1s) and Υ(1s) at various energies in pPb and PbPb collisions at the LHC. The calculations were carried out in the framework of perturbative two-gluon exchange formalism with different nuclear gluon distributions and a detailed exposition can be found in [6] (see also [19,20]). In the current article we extend these previous studies by considering, in addition to J/ψ(1s) and Υ(1s), the exclusive photoproduction of ψ(2s), Υ(2s), and Υ(3s) in ultraperipheral pPb (at √ s N N = 5 TeV) and PbPb (at √ s N N = 2.76 TeV) collisions at the LHC. For brevity we will refer to J/ψ(1s) and ψ(2s) collectively as ψ mesons, and Υ(1s), Υ(2s), and Υ(3s) as Υ mesons. The calculation framework remains essentially unchanged; the only additional assumption is that the multiplicative correction factor ζ V introduced in [6] and determined for J/ψ(1s) is applicable to ψ(2s). The requisite input masses and widths of these mesons are taken from [21] and are shown in Table I. As in previous studies we use gluon distributions from MSTW08 [22], EPS08 [23], EPS09 [24], and HKN07

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confidence: 99%

Coherent photoproduction ofψandΥmesons in ultraperipheralpPb and PbPb collisions at the CERN Large Hadron Collider at
Adeluyi
¹
,
Nguyen
²

2013
Phys. Rev. C
23
1
20
0
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“…The recently published study [6] demonstrates that it is feasible to select UPC at the LHC and that the rates for many processes of the dipole -nucleus interactions are high enough. This includes the process of coherent photoproduction of J/ψ [7]. However, this process could only be effectively studied up to relatively small energies W γN ∼ 130 GeV due to the inability to separate contributions due to the lower and higher energy photons emitted by two colliding ions.…”

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Tracking Fast Small Color Dipoles through Strong Gluon Fields at the LHC

Frankfurt

Strikman²,

Zhalov

2009

Phys. Rev. Lett.

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We argue that the process γ + A → J/ψ + " gap" + X at large momentum transfer q 2 provides a quick and effective way to test onset of a novel perturbative QCD regime of strong absorption for the interaction of small dipoles at the collider energies. We find that already the first heavy ion run at the LHC will allow to study this reaction with sufficient statistics via ultraperipheral collisions hence probing the interaction of qq dipoles of sizes ∼ 0.2fm with nuclear media down to x ∼ 10 −5 .Keywords: Quantum chromodynamics, diffraction, small x parton distributions Soon after J/ψ was discovered, the J/ψ photoproduction experiments on nuclear targets have established that nuclei are practically transparent to the J/ψ's produced at photon energies in the range ∼ 20 GeV ÷ 120GeV [1, 2]. The absorptive cross section, σ J/ψN abs , was found to be close to ∼ 4 mb that is much smaller than the cross section of interaction of ordinary mesons ∼ 25 mb. The observed transparency is natural within the LowNussinov model of two gluon exchange where the cross section of hadron interaction with a small color singlet dipole quark-antiquark configuration in the photon wave function is proportional to the square of the transverse size of the color dipole [3,4]. Note, that the average size of cc configurations involved in photoproduction of J/ψ is significantly smaller than the J/ψ size. Such suppression of interactions of small dipoles is well known effect in electrodynamics -for example, a muonium can propagate through the media much easier than a positronium.Within the leading ln Q 2 , ln(1/x) approximations of perturbative QCD one expects (in difference from the Low -Nussinov model) that the cross section of the interaction of small dipoles with hadrons should increase rapidly with increase of invariant dipole-hadron energy W γN = √ s due to the growth of the gluon fields in hadron targets at small x ∝ s −1 :where F 2 = 3(4/3) is the Casimir operator for the twogluon (qq) dipole, and λ ∼ 4 − 9. For a dipole of a size ∼ 0.25 fm relevant for production of J/ψ Eq.(1) corresponds to energy dependence ∝ s 0.2 and describes well behaviour of the both exclusive electro production of vector mesons and the inclusive cross section of deep inelastic electron-proton scattering scattering observed at HERA, for a review and references see [5].A naive extrapolation of the observed pattern to LHC energies indicates that the strength of this interaction may reach values comparable to that experienced by light hadrons, leading to a new regime of strong interaction physics at the LHC characterized by a strong absorption of small color dipoles by the media. On the other hand it is evident that to avoid conflict with probability conservation starting from some energies such rapid increase of cross section should be tamed.So, the question is whether it will be possible at LHC to observe this new perturbative QCD regime when the coupling constant is small but the interaction is strong. In practice, it is very difficult to devise a high energy probe ...

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“…This fit (Fig.2) gives a good description of all existing data. At the same time, we found that the low energy extrapolation of the Landshoff-Donnachie parametrization of the J/ψ N cross section [18] which we have used in our previous paper [12] to estimate coherent J/ψ photoproduction off nuclei in the UPC of heavy ions significantly overestimates the value of cross section at rapidities away from zero. Moreover, from our study of the low energy coherent photoproduction of J/ψ off nuclear targets [14] we find that approximation coherent incoherent incoherent 0n,0n incoherent 0n,Xn Impulse 212 µb 264 µb 38 µb 215 µb Glauber 168 µb 210 µb 30 µb 170 µb Table 1: Total cross sections of coherent and incoherent J/ψ photoproduction calculated in the Impulse and the Glauber approximations for Au + Au → Au + X + J/ψ in UPC at RHIC.…”

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confidence: 75%

“…[4], [6], [12]) with the conclusion that the rates should be sufficiently high to study the process.…”

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confidence: 99%

Neutron tagging of quasielastic J/ψ photoproduction off nucleus in ultraperipheral heavy ion collisions at RHIC energies

Strikman¹,

Tverskoy²,

Zhalov³

2005

Physics Letters B

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We compare the coherent and quasielastic J/ψ photoproduction in the peripheral heavy ion collisions in kinematics of RHIC. Our improved estimate of the total coherent cross section is a factor of two smaller than the earlier ones. We find that the counting rate of quasielastic J/ψ photoproduction tagged by neutrons emitted due to cascading of the recoiled nucleon within the residual nucleus exceeds the rate of the coherent events. We argue that measurements of this process can be used to learn about the dynamics of color dipole-nucleon interactions in nuclei in the wide effective range of energies of γA interactions.The impressive program of the studies of hard high energy electroweak interactions with nucleons is being performed at HERA for about ten years. Unfortunately, it will not be followed by the corresponding program of studies of the interactions with nuclei in the near future.In this situation it is important to continue at least some of these studies (see for review Refs.[1], [2]) using possibilities which become available at the heavy ion colliders due to ultraperipheral collisions (UPC) of nuclei in which nuclei pass at impact parameters b > 2R A .Recent observation of coherent ρ-meson production in the UPC of nuclei at RHIC [3] has demonstrated the feasibility of this approach. The measured cross section of the coherent ρ meson photoproduction agrees well with theoretical predictions (see, for example, Refs.[4],[5], [6]). It was also demonstrated experimentally that a noticeable fraction of the coherent events is followed by the Coulomb induced neutron emission. So far, both the experimental and the theoretical studies were focusing on coherent production of vector mesons (VM). Though the coherent production of the vector mesons is rather easy to identify by selecting events where transverse momentum of the VM is sufficiently small, ≤ √ 3/R A , it is very difficult to determine whether a left or right moving nucleus was the source of the photon which converted into a VM. Since the photon flux strongly decreases with an increase in the photon energy, this makes it very difficult to study the photoproduction of the VM 1

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Fading out of J/ψ color transparency in high energy heavy ion peripheral collisions

Cited by 52 publications

References 28 publications

Coherent photoproduction ofψandΥmesons in ultraperipheralpPb and PbPb collisions at the CERN Large Hadron Collider at
Adeluyi
¹
,
Nguyen
²

2013
Phys. Rev. C
23
1
20
0
View full text Add to dashboard Cite

Coherent photoproduction ofψandΥmesons in ultraperipheralpPb and PbPb collisions at the CERN Large Hadron Collider at
Adeluyi
¹
,
Nguyen
²

2013
Phys. Rev. C
23
1
20
0
View full text Add to dashboard Cite

Tracking Fast Small Color Dipoles through Strong Gluon Fields at the LHC

Neutron tagging of quasielastic J/ψ photoproduction off nucleus in ultraperipheral heavy ion collisions at RHIC energies

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Fading out of J/ψ color transparency in high energy heavy ion peripheral collisions

Cited by 52 publications

References 28 publications

Coherent photoproduction ofψandΥmesons in ultraperipheralpPb and PbPb collisions at the CERN Large Hadron Collider atAdeluyi1, Nguyen2 2013Phys. Rev. C231200View full textAdd to dashboardCite

Coherent photoproduction ofψandΥmesons in ultraperipheralpPb and PbPb collisions at the CERN Large Hadron Collider atAdeluyi1, Nguyen2 2013Phys. Rev. C231200View full textAdd to dashboardCite

Tracking Fast Small Color Dipoles through Strong Gluon Fields at the LHC

Neutron tagging of quasielastic J/ψ photoproduction off nucleus in ultraperipheral heavy ion collisions at RHIC energies

Contact Info

Product

Resources

About

Coherent photoproduction ofψandΥmesons in ultraperipheralpPb and PbPb collisions at the CERN Large Hadron Collider at
Adeluyi
¹
,
Nguyen
²

2013
Phys. Rev. C
23
1
20
0
View full text Add to dashboard Cite

Coherent photoproduction ofψandΥmesons in ultraperipheralpPb and PbPb collisions at the CERN Large Hadron Collider at
Adeluyi
¹
,
Nguyen
²

2013
Phys. Rev. C
23
1
20
0
View full text Add to dashboard Cite