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

Abstract

Large azimuthal quadrupole and octupole asymmetries have recently been found in p+Pb collisions at the LHC. We argue that these might arise from a projectile dipole scattering off fluctuations in the target with a size on the order of the dipole. In a holographic scenario, parity even angular moments $v_{2n}$ are generated by the real part of the light-like Wilson loop due to the contribution from the background metric to the Nambu-Goto action. On the other hand, parity odd moments $v_{2n+1}$ must arise from the imaginary part of the light-like Wilson loop, which is naturally induced by a fluctuating Neveu-Schwarz 2-form.

Comments: improved discussion, clearer introduction and outline, added references, to appear in Physical Review D