Freja Thoresen
Niels Bohr Institute
on behalf of the ALICE Collaboration
Â
July 13, 2019
\( v_2 \)
\( v_3 \)
\( v_1 \)
\( v_4 \)
This talk:
Forward Multiplicity Detector (FMD)
Time Projection Chamber (TPC)
V0 Scintillators
Inner Tracking System (ITS)
Â
Â
How big should a \( \eta \)-gap be?
\( \langle 2 \rangle = \frac{p_{n,1}^A Q_{-n,1}^B}{p_{0,1}^A Q_{0,1}^B} \)
\( v_n\{2, |\Delta \eta |> x \} = \sqrt{\langle \langle 2Â \rangle \rangle } \)
\[Â \langle v_n(\eta_a)v_n(\eta_b)Â \rangle = \langle v_n(\eta_a)\rangle \langle v_n(\eta_b) \rangle \]
\[ f_2(\Delta \eta) = \langle v_n(\eta_a)\rangle / \langle v_n(\eta_b) \rangle , \Delta \eta = \eta_a - \eta_b\]
Â
Figure: Factorization from Pb-Pb 5.02 TeV data.
Figure: Factorization from Pb-Pb 5.02 TeVÂ AMPT w. String Melting.
\( \Delta \eta \)
TPC
FMD
FMD
TPC
FMD
FMD
Figures: Beginning of arrow is differential region, end of arrow is reference region
Figure: Multiplicity densities of charged particles hitting the SPD and FMD in a HIJING simulation with GEANT3 as transport code for 0 âˆ’ 5% central events.
Secondaries distributed around primaries: $$P(\varphi') = f(\varphi) \circ P(\varphi)$$
Observed in the detector: \(Â \Delta \varphi' = \varphi_1' - \varphi_2\)
Â
Â
Â
Â
Â
If we know \(\mathcal{F}(f(\varphi)) \) we can extract \( \langle \langle v_n' v_n \rangle \rangle^{true} \)
Figure: Illustration of smearing in \( \varphi \) by secondary particles
Figure: Distribution of a secondary particle around its primary mother particle. Plots are shifted by a constant.
Figure: Correction values to \( v_2 \)
Figure: \( v_n\{2,|\Delta \eta| > 0\}\) as a function of \( \eta \).
NEW
Ordering of harmonics \( v_2 > v_3 > v_4 \)
\( v_n \) increasing from 0 - 40 %
Wide range in \( \eta \) shows \( v_n \) decreasing as a function of \( | \eta | \)
Figure: \( v_n\{2,|\Delta \eta| > 0\}\) as a function of \( \eta \).
NEW
Ordering of harmonics \( v_2 > v_3 > v_4 \)
\( v_n \) increasing from 0 - 40 %
Wide range in \( \eta \) shows \( v_n \) decreasing as a function of \( | \eta | \)
Figure: \( v_2\{2,|\Delta \eta| > 2\}\) and \(v_2\{4,|\Delta \eta| > 0\}\) as a function of \( \eta \).
NEW
Figure: \( v_2\{2,|\Delta \eta| > 2\}\) and \(v_2\{4,|\Delta \eta| > 0\}\) as a function of \( \eta \).
NEW
AMPT has qualitative agreement, but improvements are needed
Future comparisons to 3+1D hydrodynamic calculations:
can constrain the initial state models
study longitudinal dynamics of the created hot and dense matter
Figure: \( p_T\) differential flow measurements.Â
Figure: Data points: \( v_n \{ 2\},|\Delta \eta|> 0 \) in Pb-Pb 5.02 TeV.
Boxes: Standard Q-cumulant \( v_n \{ 2\} \) from [ALICE Collaboration,
Phys.Lett. B762 (2016)] in Pb-Pb 2.76 TeV.
Figure: Data points: \( v_2 \{ 2\},|\Delta \eta|> 2 \) and \( v_2 \{ 4\},|\Delta \eta|> 0 \) in Pb-Pb 5.02 TeV.
Boxes: Standard Q-cumulant \( v_2 \{ 2\} \) and \( v_2 \{ 4\} \) from [ALICE Collaboration, Phys.Lett. B762 (2016)] in Pb-Pb 2.76 TeV.
Figure: Widths of peaks of the distributions.
Figure: Distribution of a secondary particle around its primary mother particle. Plots are shifted by a constant.
Figure: Correction to \(v_3\) for the contamination of secondary particles in the FMD.
Figure: Correction to \(v_3\) for the contamination of secondary particles in the FMD.