Disappearance of squeezed back-to-back correlations: a new signal of hadron freeze-out from a supercooled quark gluon plasma

Csörgő, T.; Padula, Sandra S.

doi:10.1590/s0103-97332007000600012

Cited by 9 publications

(10 citation statements)

References 37 publications

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“…We thus obtain a back-to-back HBT correlation resulting from multiple rescatterings in nuclei. (The origin of our back-to-back HBT correlations is different from that of the back-to-back HBT-like correlations proposed in [79,80]. )…”

Section: Long-range Rapidity Correlations: Away-side and Near-sidcontrasting

confidence: 69%

Long-range rapidity correlations in heavy–light ion collisions

2013

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We study two-particle long-range rapidity correlations arising in the early stages of heavy ion collisions in the saturation/Color Glass Condensate framework, assuming for simplicity that one colliding nucleus is much larger than the other. We calculate the two-gluon production cross section while including all-order saturation effects in the heavy nucleus with the lowest-order rescattering in the lighter nucleus. We find four types of correlations in the two-gluon production cross section: (i) geometric correlations, (ii) HBT correlations accompanied by a back-to-back maximum, (iii) away-side correlations, and (iv) near-side azimuthal correlations which are long-range in rapidity. The geometric correlations (i) are due to the fact that nucleons are correlated by simply being confined within the same nucleus and may lead to long-range rapidity correlations for the produced particles without strong azimuthal angle dependence. Somewhat surprisingly, long-range rapidity correlations (iii) and (iv) have exactly the same amplitudes along with azimuthal and rapidity shapes: one centered around ∆φ = π with the other one centered around ∆φ = 0 (here ∆φ is the azimuthal angle between the two produced gluons). We thus observe that the early-time CGC dynamics in nucleus-nucleus collisions generates azimuthal non-flow correlations which are qualitatively different from jet correlations by being long-range in rapidity. If strong enough, they have the potential of mimicking the elliptic (and higher-order even-harmonic) flow in the di-hadron correlators: one may need to take them into account in the experimental determination of the flow observables.PACS numbers: 25.75.Gz, 12.38.Bx, 12.38.Cy I. INTRODUCTIONLong-range rapidity correlations between pairs of hadrons produced at small azimuthal angles with respect to each other were discovered recently in heavy ion (AA) [1-4], proton-proton (pp) [5], and proton-nucleus (pA) collisions [6]. Due to the particular shape of the corresponding correlation function, with a narrow correlation in the azimuthal angle ∆φ and a wide correlation in pseudo-rapidity separation ∆η, these correlations are often referred to as the "ridge".There appears to be a consensus in the community that the origin of these long-range rapidity correlations is in the very early-time dynamics immediately following the collision. A simple causality argument demonstrates that a correlation between two hadrons produced far apart in rapidity may arise only in their common causal past, that is, in the early stages of the collision [7,8]. However, the detailed dynamical origin of these "ridge" correlations is not completely clear.It has been proposed in the literature [7-15] that the "ridge" correlations may arise in the classical gluon field dynamics of the parton saturation physics/Color Glass Condensate (CGC). (For reviews of saturation/CGC physics see [16][17][18][19][20].) Indeed classical gluon fields, which in the McLerran-Venugopalan (MV) model [21][22][23] dominate gluon production in heavy ion collisions,...

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Section: Long-range Rapidity Correlations: Away-side and Near-sidcontrasting

confidence: 69%

Long-range rapidity correlations in heavy–light ion collisions

2013

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“…We thus obtain a back-to-back HBT correlation resulting from multiple rescatterings in nuclei. (The origin of our back-toback HBT correlations is different from that of the back-to-back HBT-like correlations proposed in [102,103]. )…”

Section: Long-range Rapidity Correlations: Away-side and Nearside; Hbcontrasting

confidence: 67%

Two-gluon correlations in heavy–light ion collisions

Wertepny

2014

Nuclear Physics A

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We studied the initial, high-energy scatterings in heavy ion collisions using the saturation/Color Glass Condensate framework, with a focus on two-particle longrange rapidity correlations. These two-particle correlations are modeled as two-gluon correlations, assuming that the kinetic information of the gluons survives the evolution of the system and presents itself in the final state particles. We calculate the two-gluon production cross section using the saturation framework in the heavy-light ion regime, where we consider all-order saturation effects in the heavy nucleus while considering only two-orders in saturation effects in the light ion.The two-gluon production cross section produces four types of correlations: (i) geometric correlations, (ii) Hanbury Brown and Twiss (HBT) like correlations accompanied by a back-to-back maximum, (iii) near-side correlations, and (iv) away-side azimuthal correlations. All of these correlations are long-range in rapidity. The geometric correlations (i) are due to the fact that nucleons are correlated by simply being confined within the same nucleus and may lead to long-range rapidity correlations for the produced particles without strong azimuthal angle dependence. Long-range rapidity correlations (iii) and (iv) have exactly the same amplitudes along with azimuthal and rapidity shapes: one centered around ∆φ = 0 and the other one centered around ∆φ = π (here ∆φ is the azimuthal angle between the two produced gluons).

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“…(7) was suggested in Ref. [3] and adopted in previous studies [4,7,8,[11][12][13][14][15][16]. Either of the factors in Eq.…”

Section: Results Formentioning

confidence: 99%

“…We use suitable variables introduced previously [8,[10][11][12][13][14][15] to investigate the expected behavior of the squeezed correlation function in an experimental search of the effect. This is studied by plotting C s (K 12 , q 12 , m * ) in terms of the average momentum of the pair, 2|K 12 |, and its relative momentum, |q 12 |.…”

Section: Discussionmentioning

confidence: 99%

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SqueezedK+K−correlations in high energy heavy ion collisions

Dudek

Padula

2010

Phys. Rev. C

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The hot and dense medium formed in high energy heavy ion collisions may modify some hadronic properties. In particular, if hadron masses are shifted in-medium, it was demonstrated that this could lead to back-to-back squeezed correlations (BBC) of particle-antiparticle pairs. Although well-established theoretically, the squeezed correlations have not yet been discovered experimentally. A method has been suggested for the empirical search of this effect, which was previously illustrated for φφ pairs. We apply here the formalism and the suggested method to the case of K + K − pairs, since they may be easier to identify experimentally. The time distribution of the emission process plays a crucial role in the survival of the BBC's. We analyze the cases where the emission is supposed to occur suddenly or via a Lorentzian distribution, and compare with the case of a Lévy distribution in time. Effects of squeezing on the correlation function of identical particles are also analyzed.

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Disappearance of squeezed back-to-back correlations: a new signal of hadron freeze-out from a supercooled quark gluon plasma

Cited by 9 publications

References 37 publications

Long-range rapidity correlations in heavy–light ion collisions

Long-range rapidity correlations in heavy–light ion collisions

Two-gluon correlations in heavy–light ion collisions

SqueezedK+K−correlations in high energy heavy ion collisions

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