Non-Abelian bremsstrahlung and azimuthal asymmetries in high energy p+A reactions

Gyulassy, Miklós Pál and Lévai, Péter and Vitev, I. and Biró, Tamás Sándor (2014) Non-Abelian bremsstrahlung and azimuthal asymmetries in high energy p+A reactions. PHYSICAL REVIEW D, 90 (5). ISSN 2470-0010

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Abstract

We apply the GLV reaction operator solution to the Vitev-Gunion-Bertsch (VGB) boundary conditions to compute the all-order in nuclear opacity non-abelian gluon bremsstrahlung of event- by-event fluctuating beam jets in nuclear collisions. We evaluate analytically azimuthal Fourier moments of single gluon, vM n {1}, and even number 2` gluon, vM n {2`} inclusive distributions in high energy p+A reactions as a function of harmonic n, target recoil cluster number, M , and gluon number, 2`, at RHIC and LHC. Multiple resolved clusters of recoiling target beam jets together with the projectile beam jet form Color Scintillation Antenna (CSA) arrays that lead to character- istic boost non-invariant trapezoidal rapidity distributions in asymmetric B + A nuclear collisions. The scaling of intrinsically azimuthally anisotropic and long range in η nature of the non-abelian bremsstrahlung leads to vn moments that are similar to results from hydrodynamic models, but due entirely to non-abelian wave interference phenomena sourced by the fluctuating CSA. Our analytic non-flow solutions are similar to recent numerical saturation model predictions but differ by pre- dicting a simple power-law hierarchy of both even and odd vn without invoking kT factorization. A test of CSA mechanism is the predicted nearly linear η rapidity dependence of the vn(kT , η). Non- abelian beam jet bremsstrahlung may thus provide a simple analytic solution to Beam Energy Scan (BES) puzzle of the near √s independence of vn(pT ) moments observed down to 10 AGeV where large-x valence quark beam jets dominate inelastic dynamics. Recoil bremsstrahlung from multiple independent CSA clusters could also provide a partial explanation for the unexpected similarity of vn in p(D) + A and non-central A + A at same dN/dη multiplicity as observed at RHIC and LHC.

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