Transverse momentum and process dependent azimuthal anisotropies in $$\sqrt{s_{\mathrm {NN}}}=8.16$$ TeV p+Pb collisions with the ATLAS detector
G. Aad, B. Abbott, D. C. Abbott, A. Abed Abud, K. Abeling, D. K. Abhayasinghe, S. H. Abidi, O. S. AbouZeid, N. L. Abraham, H. Abramowicz, H. Abreu, Y. Abulaiti, B. S. Acharya, B. Achkar, S. Adachi, L. Adámek, C. Adam Bourdarios, L. Adamczyk, L. Adamek, J. Adelman, M. Adersberger, A. Adiguzel, S. Adorni, T. Adye, A. A. Affolder, Y. Afik, C. Agapopoulou, M. N. Agaras, A. Aggarwal, C. Agheorghiesei, J. A. Aguilar–Saavedra, F. Ahmadov, W. S. Ahmed, X. Ai, G. Aielli, S. Akatsuka, T. P. A. Åkesson, E. Akilli, A. V. Akimov, K. Al Khoury, G. L. Alberghi, J. Albert, M. J. Alconada Verzini, S. Alderweireldt, M. Aleksa, I. N. Aleksandrov, C. Alexa, T. Alexopoulos, A. Alfonsi, F. Alfonsi, M. Alhroob, B. Ali, M. Aliev, G. Alimonti, C. Allaire, B. M. M. Allbrooke, B. W. Allen, P. P. Allport, A. Aloisio, F. Alonso, C. Alpigiani, A. A. Alshehri, M. Alvarez Estevez, M. G. Alviggi, Y. Amaral Coutinho, A. Ambler, L. Ambroz, C. Amelung, D. Amidei, S. P. Amor Dos Santos, S. Amoroso, C.S. Amrouche, F. F. An, C. Anastopoulos, N. Andari, T. Andeen, C. F. Anders, J. K. Anders, A. Andreazza, V. Andrei, C. R. Anelli, S. Angelidakis, A. Angerami, A. V. Anisenkov, A. Annovi, C. Antel, M. T. Anthony, E. Antipov, M. Antonelli, D. J. A. Antrim, F. Anulli, M. Aoki, J. A. Aparisi Pozo, L. Aperio Bella, J. P. Araque, V. Araujo Ferraz, R. Araujo Pereira, C. Arcangeletti, A. T. H. Arce, F. A. Arduh
Abstract
Abstract The azimuthal anisotropy of charged particles produced in $$\sqrt{s_{\mathrm {NN}}}=8.16$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msqrt><mml:msub><mml:mi>s</mml:mi><mml:mi>NN</mml:mi></mml:msub></mml:msqrt><mml:mo>=</mml:mo><mml:mn>8.16</mml:mn></mml:mrow></mml:math> TeV p +Pb collisions is measured with the ATLAS detector at the LHC. The data correspond to an integrated luminosity of 165 $$\mathrm {nb}^{-1}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mrow><mml:mi>nb</mml:mi></mml:mrow><mml:mrow><mml:mo>-</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msup></mml:math> that was collected in 2016. Azimuthal anisotropy coefficients, elliptic $$v_2$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>v</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math> and triangular $$v_3$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>v</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:math> , extracted using two-particle correlations with a non-flow template fit procedure, are presented as a function of particle transverse momentum ( $$p_\mathrm {T}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>p</mml:mi><mml:mi>T</mml:mi></mml:msub></mml:math> ) between 0.5 and 50 GeV. The $$v_2$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>v</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math> results are also reported as a function of centrality in three different particle $$p_\mathrm {T}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>p</mml:mi><mml:mi>T</mml:mi></mml:msub></mml:math> intervals. The results are reported from minimum-bias events and jet-triggered events, where two jet $$p_\mathrm {T}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>p</mml:mi><mml:mi>T</mml:mi></mml:msub></mml:math> thresholds are used. The anisotropies for particles with $$p_\mathrm {T}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>p</mml:mi><mml:mi>T</mml:mi></mml:msub></mml:math> less than about 2 GeV are consistent with hydrodynamic flow expectations, while the significant non-zero anisotropies for $$p_\mathrm {T}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>p</mml:mi><mml:mi>T</mml:mi></mml:msub></mml:math> in the range 9–50 GeV are not explained within current theoretical frameworks. In the $$p_\mathrm {T}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>p</mml:mi><mml:mi>T</mml:mi></mml:msub></mml:math> range 2–9 GeV, the anisotropies are larger in minimum-bias than in jet-triggered events. Possible origins of these effects, such as the changing admixture of particles from hard scattering and the underlying event, are discussed.