Directed flow of D meson in nuclear collisions at the LHC

1. ID card

Title: Directed flow of D meson in nuclear collisions at the LHC

Contact: Zhoudunming Tu (ztu@cernNOSPAMPLEASE.ch)

ARC: Fuqiang Wang (Chair)

Journal: PAS-ONLY

Draft:

CADI: http://cms.cern.ch/iCMS/analysisadmin/cadilines?line=HIN-18-013

Hypernews:

Pre-approval:

homework

ARC review:

ARC_1

Approval:

Approved plots:

CWR:

FR:

2. Comments:

3. References papers from Theory

Title	Authors	Year	CADI line	Paper link
Directed Flow of Charm Quarks as a Witness of the Initial Strong Magnetic Field in Ultra-Relativistic Heavy Ion Collisions	Santosh. Das	2016		https://arxiv.org/abs/1608.02231
Magnetohydrodynamics, charged currents and directed flow in heavy ion collisions	Gursoy	2014		https://arxiv.org/abs/1401.3805

4. Task list

• Optimization
  • D0 significance
    • Re-check cuts for mid- and forward rapidity to make sure if they are optimal
    • Vary pT cut around pT>1 GeV (e.g., 0.1 GeV step) to find the cut with best significance
  • First-order plane:
    • Try tracker EP1 in eta region where v1 peaks. Vary track pT cutoff to optimize EP1 resolution, i.e., maximize Ntrk*v1^2.
• Data: try MB data sets, scan in centrality 0-100%, 10-100%, 20-100%.
• MC input: Use more updated MC input from Hao Qiu to derive the swap MC with finalized D0 cut.

5. D0 cuts

The most optimized cuts for the following rapidity bins |y| < 0.6, 0.6 < |y| < 1.2, 1.2 < |y| < 2.0

- 3D Pointing Angle High = {0.12, 0.08, 0.12}

- Vertex Probability Low = {0.04, 0.0, 0.08}

- 3D Decay Length Significance Low = {3.5, 5.0, 5.0}

- pT of daugther tracks Low = {1.5, 1.5, 1.5}

- D0 DCA High = {0.02, 0.012, 0.008}

The pT cutoff of D0 is around 2.0 ! GeV /c

The suggested skim selection is:

- 3D Pointing Angle < 0.15

- Vertex Probability > 0.0

- 3D Decay Length Significance > 3.0

- pT of daughters > 1.2

- D0 DCA < 0.025

- D0 pT > 1.2

-- ZhoudunmingTu - 2017-11-05