Study of collective anisotropies $$v_2$$ and $$v_3$$ and their fluctuations in pA collisions at LHC within a relativistic transport approach
Yifeng Sun, Salvatore Plumari, Vincenzo Greco
Abstract
Abstract We have developed a relativistic transport approach at fixed $$\eta /s(T)$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>η</mml:mi><mml:mo>/</mml:mo><mml:mi>s</mml:mi><mml:mo>(</mml:mo><mml:mi>T</mml:mi><mml:mo>)</mml:mo></mml:mrow></mml:math> that incorporates initial space fluctuations generated by wounded quark model to study the hadron observables in 5.02 TeV p + Pb collisions. We find that our approach is able to correctly predict quite well several existing experimental measurements assuming a matter with $$\eta /s=1/4\pi $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>η</mml:mi><mml:mo>/</mml:mo><mml:mi>s</mml:mi><mml:mo>=</mml:mo><mml:mn>1</mml:mn><mml:mo>/</mml:mo><mml:mn>4</mml:mn><mml:mi>π</mml:mi></mml:mrow></mml:math> , a result similar to previous studies within a viscous hydrodynamics approach. Besides, we further discuss the sensitivity of the results on both $$\eta /s(T)$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>η</mml:mi><mml:mo>/</mml:mo><mml:mi>s</mml:mi><mml:mo>(</mml:mo><mml:mi>T</mml:mi><mml:mo>)</mml:mo></mml:mrow></mml:math> and the smearing width. Our transport approach has the possibility to include in initial conditions the power law tail associated to minijet, and this improvement extends the agreement with the experimental data to higher $$p_T$$ <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> ranges. We also perform a comparison to Pb + Pb collisions pointing out that even if the collective flows have a similar magnitude the features of the matter created are different. By studying the correlation between collective flows and initial geometry, we find that the correlation decreases faster in small systems with the increase of n and centrality. In particular we show that the variance of $$\sigma _{v_n}/\langle v_n\rangle $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>σ</mml:mi><mml:msub><mml:mi>v</mml:mi><mml:mi>n</mml:mi></mml:msub></mml:msub><mml:mo>/</mml:mo><mml:mrow><mml:mo>⟨</mml:mo><mml:msub><mml:mi>v</mml:mi><mml:mi>n</mml:mi></mml:msub><mml:mo>⟩</mml:mo></mml:mrow></mml:mrow></mml:math> has a quite different evolution with centrality for p + Pb, so their measurement could provide some further hint about the correctness of current modelling.