XXVIII International Workshop on Deep-Inelastic Scattering and Related Subjects

Two-particle azimuthal correlations as a probe of collective behaviour in ep scattering at HERA

14 Apr 2021, 08:36

18m

Virtual (Stony Brook, NY)

Contributed Talk Small-x, Diffraction and Vector Mesons Small-x, Diffraction and Vector Mesons

Speaker

Dhevan Gangadharan (Universitat Heidelberg)

Description

Two-particle azimuthal correlations have been measured in neutral current deep inelastic ep scattering with virtuality $Q^2>5$ GeV${}^2$ at a centre-of-mass energy $\sqrt{𝑠}=318$ GeV recorded with the ZEUS detector at HERA. The correlations of charged particles have been measured in the range of laboratory pseudorapidity $-1.5<\eta <2.0$ and transverse momentum $0.1<p_T<5.0$ GeV and event multiplicities $N_{ch}$ up to six times larger than the average $⟨N_{ch}⟩\hspace{0.17em}\approx \hspace{0.17em}5$. The two-particle correlations have been measured in terms of the angular observables $c_{n}2\hspace{0.17em}=\hspace{0.17em}〈〈\cos n\Delta \phi 〉〉$, where $n$ is between 1 and 4 and $∆\phi$ is the relative azimuthal angle between the two particles. Comparisons with available models of deep inelastic scattering, which are tuned to reproduce inclusive particle production, suggest that the measured two-particle correlations are dominated by contributions from multijet production. The dependence of the correlations as a function of $Q^2$ has also been studied as well as the correlations in photoproduction events ($Q^2\approx 0$). The correlations observed here do not indicate the kind of collective behaviour recently observed at the highest RHIC and LHC energies in high-multiplicity hadronic collisions.

Presentation materials

DIS2021_Dhevan.pdf

Youtube Link