22-27 September 2016
East Lake International Conference Center
Asia/Chongqing timezone
<a href="http://hp2016.ccnu.edu.cn">http://hp2016.ccnu.edu.cn</a>

Measurement of long-range azimuthal anisotropies and of forward-backward multiplicity correlations and longitudinal flow with the ATLAS detector

25 Sep 2016, 12:00
Shi-Yan Hall (East Lake International Conference Center)

Shi-Yan Hall

East Lake International Conference Center

Donghu Road 142, Wuchang District, Wuhan, Hubei, China


Alexander Milov (Weizmann Institute of Science (IL))


ATLAS measurements of correlations between particle pairs in relative azimuthal angle ($\Delta\phi$) and pseudorapidity separation ($\Delta\eta$), in $pp$ collisions at $\sqrt{s}$=2.76, 5.02 and 13~TeV, and in $p$+Pb collisions at $\sqrt{s_{\mathrm{NN}}}$=5.02~TeV are presented. Prior measurements have shown that in $pp$ collisions with a large multiplicity of produced particles, a long-range structure,commonly called the ``ridge'', develops along $\Delta\eta$ at $\Delta\phi\sim$0. However, due to the presence of the large away-side jet, the full $\Delta\phi$ dependence of the long-range correlation could not be studied previously. In this analysis, a template fitting procedure is implemented to determine the contributions from dijets to the correlations, using low-multiplicity events, and extract the genuine long-range correlation. The long-range correlations are shown to be present even in events with a small multiplicity of produced particles, implying that the long-range correlations are not unique to rare high multiplicity events. The properties of the correlation are shown to be remarkably similar to that observed in $p$+Pb collisions. Study of these long range correlations using multi-particle cumulants are also presented. New results on how the long-range correlations are affected by the presence or absence of hard processes in the $pp$ collision are presented.

Presentation type Oral

Primary author

Alexander Milov (Weizmann Institute of Science (IL))

Presentation Materials