Azimuthal asymmetries in high-energy collisions of protons with holographic shockwaves

Noronha, Jorge; Dumitru, Adrian

doi:10.1103/physrevd.89.094008

Cited by 17 publications

(20 citation statements)

References 56 publications

(59 reference statements)

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“…This resembles the situation encountered in ref [10] where the dipole S-matrix was computed from the AdS/CFT correspondence: the Nambu-Goto action involves an integration of the (fluctuating) target density along the string connecting the quark and anti-quark. In case that the fluctuations occur on scales larger than ∼ r, eq.…”

Section: Models For the Imaginary Part Of The Dipole Scattering Ammentioning

confidence: 59%

“…These arise from the C-odd imaginary part of the dipole S-matrix, analogous to single transverse spin asymmetries discussed before by Kovchegov and Sievert [8]. However, in order to obtain non-zero v 3 we have found it necessary to generalize the odderon to a string-like operator [10] so that the dipole can couple to hard fluctuations of wave length below the dipole size r ∼ 1/p T . Fixing two parameters, the fluctuation amplitude B and cutoff Q c , we find that the odderon model provides a reasonably good simultaneous description of v 1 {2}(p T ) and v 3 {2}(p T ) measured in high multiplicity p+Pb collisions at the LHC.…”

Section: Discussionmentioning

confidence: 88%

“…For single-spin asymmetries in collisions of polarized protons with a heavy ion, the preferred direction is due to the polarization of the projectile [8]. Here, we explore the scenario that rotational symmetry is broken by a condensate for the electric field E in the target [9], leading to v 2n = 0; and by spontaneous C-odd fluctuations in the target [10], leading to v 2n+1 = 0.…”

Section: Introductionmentioning

confidence: 99%

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Initial state angular asymmetries in high energy p+A collisions: Spontaneous breaking of rotational symmetry by a color electric field and C-odd fluctuations

Dumitru

Giannini

2015

Nuclear Physics A

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We present a simple model for generating initial-state azimuthal asymmetries in pA collisions from dipole scattering on an anisotropic dense target. Parity even angular harmonics arise from the C-even real part of the dipole S-matrix which spontaneously breaks rotational symmetry in two dimensions due to a condensate for the color electric field. This leads to an angular correlation with the direction of E. Parity odd harmonics are generated by the C-odd imaginary part (odderon) due to coupling to coherent target fluctuations which again break rotational invariance. We perform a first qualitative extraction of the amplitude and cutoff of C-odd fluctuations in the dense target.

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Section: Models For the Imaginary Part Of The Dipole Scattering Ammentioning

confidence: 59%

Section: Discussionmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

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Initial state angular asymmetries in high energy p+A collisions: Spontaneous breaking of rotational symmetry by a color electric field and C-odd fluctuations

Dumitru

Giannini

2015

Nuclear Physics A

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“…We note here that if one uses the Trento setup specific to LHC found in [52] of p = 0 and k = 1.4 that the initial eccentricities are even smaller and even more sensitive to the smoothing scale and even see large deviations for ε 2,2 and ε 2,3 above λ = 0.3. This shows that p+Pb collisions should be very sensitive to the underlying physics below the confinement scale, which may justify the search for alternative non-hydrodynamical explanations for the p+Pb flow harmonics data [88][89][90][91][92][93][94].…”

Section: Smoothing Out Proton-nucleus Collisionsmentioning

confidence: 99%

Sensitivity of flow harmonics to subnucleon scale fluctuations in heavy ion collisions

2016

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In this paper a new procedure to smooth out the initial energy densities of hydrodynamics is employed to show that the initial spatial eccentricities εm,n, which drive the final state flow harmonics vn, are remarkably robust with respect to variations of the underlying scale of initial energy density spatial gradients, λ, in nucleus-nucleus collisions. For √ s = 2.76 TeV Pb+Pb collisions, the εm,n's (across centrality classes) change by less than 10% if the scale of fluctuations is varied from 0.1 to 1 fm. We show, using the 2+1 Lagrangian hydrodynamic code, v-USPhydro, that this robustness is transferred to the final vn's computed within event by event viscous hydrodynamics. This indicates that the flow harmonics in nucleus-nucleus collisions are not particularly sensitive to the underlying microscopic sub-nucleon physics below the confinement scale. On the other hand, the eccentricities of top 1% high multiplicity √ s = 5.02 TeV p+Pb collisions are found to be very sensitive to sub-nucleonic scale fluctuations, which should be contrasted with the robustness found in peripheral Pb+Pb collisions with the same multiplicity.

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“…To this end several interesting observations were recently published [28][29][30][31][32][33][34][35] which could help to distinguish between competing models of p+A interactions. A simple conformal scaling argument, presented in Ref.…”

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confidence: 99%

Elliptic and Triangular Flow inp-Pb and Peripheral Pb-Pb Collisions from Parton Scatterings

2014

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Using a multiphase transport model (AMPT) we calculate the elliptic, v2, and triangular, v3, Fourier coefficients of the two-particle azimuthal correlation function in proton-nucleus (p+Pb) and peripheral nucleus-nucleus (Pb+Pb) collisions. Our results for v3 are in a good agreement with the CMS data collected at the Large Hadron Collider. The v2 coefficient is very well described in p+Pb collisions and is underestimated for higher transverse momenta in Pb+Pb interactions. The characteristic mass ordering of v2 in p+Pb is reproduced whereas for v3 this effect is not observed. We further predict the pseudorapidity dependence of v2 and v3 in p+Pb and observe that both are increasing when going from a proton side to a Pb-nucleus side. Predictions for the higher order Fourier coefficients, v4 and v5, in p+Pb are also presented. , with a modest elastic parton-parton crosssection σ = 1.5 − 3 mb, allows to understand qualitatively and quantitatively the long-range two-particle azimuthal correlation functions in proton-lead (p+Pb) and high-multiplicity proton-proton (p+p) collisions. Such correlations were recently observed by the CMS [3-5], ALICE [6,7] and ATLAS [8,9] Collaborations at the Large Hadron Collider (LHC), and by the PHENIX Collaboration in deuteron-gold collisions at the Relativistic Heavy Ion Collider (RHIC) [10].Interestingly all features of the two-particle azimuthal correlation function observed in p+Pb collisions are very similar to those observed in A+A interactions, where such correlations are commonly attributed to the hydrodynamic expansion of the produced fireball. This naturally suggests that collective physics is present in p+A collisions [1,[11][12][13][14][15][16][17]. Particularly strong evidence in favour of hydrodynamics (or any other approach where the initial coordinate space anisotropy is transformed into the final momentum anisotropy) in p+A and peripheral A+A collisions is an approximate equality of multiparticle elliptic flow cumulants, v 2 {4} ≈ v 2 {6} ≈ v 2 {8}, as predicted in Ref. [18], see also [19,20], and confirmed recently by the CMS Collaboration [21]. Other strong evidence is the characteristic mass ordering of the elliptic flow, v 2 , observed by the ALICE Collaboration in Ref. [7], and successfully reproduced by hydrodynamic calculations [22,23].The experimental data for the two-particle azimuthal correlation function can be also fitted within the color glass condensate framework [24], where the interesting part of the two-particle correlation function comes from the emission of two gluons in the so-called glasma diagram [25]. For a detailed discussion of this approach we refer the reader to Refs. [25][26][27].It is important to clarify whether the signal in p+A collisions comes form the initial or final (or both) state effects. To this end several interesting observations were recently published [28][29][30][31][32][33][34][35] which could help to distinguish between competing models of p+A interactions. A simple conformal scaling argument, presented in Ref.[31], indica...

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Azimuthal asymmetries in high-energy collisions of protons with holographic shockwaves

Cited by 17 publications

References 56 publications

Initial state angular asymmetries in high energy p+A collisions: Spontaneous breaking of rotational symmetry by a color electric field and C-odd fluctuations

Initial state angular asymmetries in high energy p+A collisions: Spontaneous breaking of rotational symmetry by a color electric field and C-odd fluctuations

Sensitivity of flow harmonics to subnucleon scale fluctuations in heavy ion collisions

Elliptic and Triangular Flow inp-Pb and Peripheral Pb-Pb Collisions from Parton Scatterings

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