TY - JOUR

T1 - Measurements of long-range azimuthal anisotropies and associated Fourier coefficients for $pp$ collisions at $\sqrt{s}=5.02$ and $13$ TeV and $p$+Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV with the ATLAS detector

AU - Clark, Philip James

AU - Leonidopoulos, Christos

AU - Martin, Victoria Jane

AU - Mills, Corrinne

AU - Collaboration, Atlas

AU - Mijovic, Liza

AU - Gao, Yanyan

AU - Farrington, Sinead

PY - 2017/8/22

Y1 - 2017/8/22

N2 - ATLAS measurements of two-particle correlations are presented for $\sqrt{s} = 5.02$ and $13$ TeV $pp$ collisions and for $\sqrt{s_{\mathrm{NN}}} = 5.02$ TeV $p$+Pb collisions at the LHC. The correlation functions are measured as a function of relative azimuthal angle $\Delta \phi$, and pseudorapidity separation $\Delta \eta$, using charged particles detected within the pseudorapidity interval $|\eta|{}2$, is studied using a template fitting procedure to remove a "back-to-back" contribution to the correlation function that primarily arises from hard-scattering processes. In addition to the elliptic, $\cos{(2\Delta\phi)}$, modulation observed in a previous measurement, the $pp$ correlation functions exhibit significant $\cos{(3\Delta\phi)}$ and $\cos{(4\Delta\phi)}$ modulation. The Fourier coefficients $v_{n,n}$ associated with the $\cos{(n\Delta\phi)}$ modulation of the correlation functions for $n =$ $2$-$4$ are measured as a function of charged-particle multiplicity and charged-particle transverse momentum. The Fourier coefficients are observed to be compatible with $\cos{(n\phi)}$ modulation of per-event single-particle azimuthal angle distributions. The single-particle Fourier coefficients $v_n$ are measured as a function of charged-particle multiplicity, and charged-particle transverse momentum for $n {=} $ $2$-$4$. The integrated luminosities used in this analysis are, $64$ $\mathrm{nb^{-1}}$ for the $\sqrt{s}=13$ TeV $pp$ data, $170$ $\mathrm{nb^{-1}}$ for the $\sqrt{s}=5.02$ TeV $pp$ data and $28$ $\mathrm{nb^{-1}}$ for the $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV $p$+Pb data.

AB - ATLAS measurements of two-particle correlations are presented for $\sqrt{s} = 5.02$ and $13$ TeV $pp$ collisions and for $\sqrt{s_{\mathrm{NN}}} = 5.02$ TeV $p$+Pb collisions at the LHC. The correlation functions are measured as a function of relative azimuthal angle $\Delta \phi$, and pseudorapidity separation $\Delta \eta$, using charged particles detected within the pseudorapidity interval $|\eta|{}2$, is studied using a template fitting procedure to remove a "back-to-back" contribution to the correlation function that primarily arises from hard-scattering processes. In addition to the elliptic, $\cos{(2\Delta\phi)}$, modulation observed in a previous measurement, the $pp$ correlation functions exhibit significant $\cos{(3\Delta\phi)}$ and $\cos{(4\Delta\phi)}$ modulation. The Fourier coefficients $v_{n,n}$ associated with the $\cos{(n\Delta\phi)}$ modulation of the correlation functions for $n =$ $2$-$4$ are measured as a function of charged-particle multiplicity and charged-particle transverse momentum. The Fourier coefficients are observed to be compatible with $\cos{(n\phi)}$ modulation of per-event single-particle azimuthal angle distributions. The single-particle Fourier coefficients $v_n$ are measured as a function of charged-particle multiplicity, and charged-particle transverse momentum for $n {=} $ $2$-$4$. The integrated luminosities used in this analysis are, $64$ $\mathrm{nb^{-1}}$ for the $\sqrt{s}=13$ TeV $pp$ data, $170$ $\mathrm{nb^{-1}}$ for the $\sqrt{s}=5.02$ TeV $pp$ data and $28$ $\mathrm{nb^{-1}}$ for the $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV $p$+Pb data.

U2 - 10.1103/PhysRevC.96.024908

DO - 10.1103/PhysRevC.96.024908

M3 - Article

VL - C96

SP - 024908

JO - Physical Review

JF - Physical Review

SN - 0031-899X

IS - 2

M1 - Aaboud:2016yar

ER -