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Low $p_{T}$ $J/\psi$ signal extraction vs $p_{T}$ in 70-90% centrality class measured at midrapidity

Figure Information
Scope: PWG
PWG-DQ (Dileptons and Quarkonia)
Energy
5.02 TeV
System
Pb-Pb
Figure Group
Low $p_{T}$ $J/\psi$ excess at midrapidity in peripheral Pb-Pb collisions at 5.02 TeV with full Run 2 + projections for Run3/4 (QM2022)
Figure Image
Figure image (.eps)
SignalExtraction_vs_pT_7090.eps
Figure image (.pdf)
SignalExtraction_vs_pT_7090.pdf
Figure Caption

The measured $p_{T}$ spectra (black marker) together  with the fit components (coloured lines) in the mass range $2.92<m_{ee}<3.16 $ GeV/c^{2}$ for the 70-90% centrality class. The total fit is represented by the black line.

Detail description

Data sample: full Run 2 data (LHC18q, LHC18r, LHC15o )

Reconstruction pass: pass 3 for LHC18q and LHC18r, pass 1 for LHC15o

Event selection:

- |vtx z| < 10 cm

- Physics selection

- Pileup cut

-  Minimum bias or semi-central trigger (available only for 2018 data set)

Track cuts:

1 .|eta|<0.9

2. total momentum of the electron candidates, p> 1 GeV/c

 

Coherent $J/\psi$ yield measured using an unbinned 2D ($m_{ee},p_{T}$ ) likelihood fit. The model constructed to fit the data is a sum of several  probability density functions (pdf). The main contributions to the fit can be grouped as: background (combinatorial+correlated), hadronic and photoproduced $J/\psi$ components. Photoproduced $J/\psi$ components are obtained from STARLIGHT + HIJING simulations.