Rescuing the nonjet (NJ) azimuth quadrupole from the flow narrative

CENPA 354290 University of Washington, Seattle, Washington, USA

Published online: 12 April 2017

Abstract

According to the flow narrative commonly applied to high-energy nuclear collisions a cylindrical-quadrupole component of 1D azimuth angular correlations is conventionally denoted by quantity υ₂ and interpreted to represent elliptic flow. Jet angular correlations may also contribute to υ₂ data “nonflow” depending on the method used to calculate υ₂, but 2D graphical methods are available to insure accurate separation. The nonjet (NJ) quadrupole has various properties inconsistent with a flow interpretation, including the observation that NJ quadrupole centrality variation in A-A collisions has no relation to strongly-varying jet modication (“jet quenching”) in those collisions commonly attributed to jet interaction with a flowing dense medium. In this presentation I describe isolation of quadrupole spectra from pt-differential υ₂(p_t) data from the RHIC and LHC. I demonstrate that quadrupole spectra have characteristics very different from the single-particle spectra for most hadrons, that quadrupole spectra indicate a common boosted hadron source for a small minority of hadrons that “carry” the NJ quadrupole structure, that the narrow source-boost distribution is characteristic of an expanding thin cylindrical shell (strongly contradicting hydro descriptions), and that in the boost frame a single universal quadrupole spectrum (Lévy distribution) on transverse mass m_t accurately describes data for several hadron species scaled according to their statistical-model abundances. The quadrupole spectrum shape changes very little from RHIC to LHC energies. Taken in combination those characteristics strongly suggest a unique nonflow (and nonjet) QCD mechanism for the NJ quadrupole conventionally represented by υ₂.