Simulation for CMS HI Dipanwita Dutta Nuclear Physics

Simulation for CMS HI Dipanwita Dutta Nuclear Physics Division Bhabha Atomic Research centre Mumbai, India Dipanwita Dutta 5 -6 April, 2007, India-CMS Meet, Chandigarh

Outline Part I • Cross-section of Z 0 (PYTHIA) • Simulation and Reconstruction of Z 0 with CMKIN+OSCAR+ORCA • Muon Reconstruction with CMSSW Part II • Future Plan: Simulation for Small mass dimuon / Real Photon with CMS Dipanwita Dutta 5 -6 April, 2007, India-CMS Meet, Chandigarh

Part I Simulation for Z 0 Dipanwita Dutta 5 -6 April, 2007, India-CMS Meet, Chandigarh

Cross-Section of Z 0 (PYTHIA) pp(Z 0) (nb/Ge. V) Total For Pb-Pb minbias collision at 5. 5 Te. V (Z 0 + -) B A 2 pp(Z 0) Z 0 p. T (Ge. V) Dipanwita Dutta 68 b 5 -6 April, 2007, India-CMS Meet, Chandigarh

Cross-section and No. of Z 0 for Pb+Pb collision s=5. 5 Te. V for Lint=0. 5 nb-1 Cross-section from PYTHIA pp (Z 0) PDF CTEQ 5 ML No. of Z 0 for central collision (CTEQ 5 M) AA=TAA(0) NN pp (Z 0) No. of Z 0 for minbias collision AA=A 2 pp (Z 0) Z 0, Z 0+jet 48 nb 54 nb 4. 3 104 1. 03 106 Z 0 16 nb 17. 5 nb 1. 4 104 3. 4 105 Z 0, Z 0+jet 8. 9 10 -1 nb 9. 5 10 -1 nb 800 1. 9 104 m. Z-5<M < m. Z+5 6. 9 10 -1 nb 7. 7 10 -1 nb 621 1. 4 104 Z 0 2. 8 10 -1 nb 257 6020 Processes For CMS p. T>3. 5 Ge. V <2. 4 Dipanwita Dutta 5 -6 April, 2007, India-CMS Meet, Chandigarh

Differential and Integrated Rate of Z 0 in Pb+Pb collision , s=5. 5 Te. V for Lint=0. 5 nb-1 │ Barrel+Endcap Barrel only Dipanwita Dutta 5 -6 April, 2007, India-CMS Meet, Chandigarh

Muon Reconstruction ● • Tag from Muon chambers • Momentum resolution from Silicon Tracker • Local Muon Reconstruction (L 1) • Stand-Alone Muon Reconstruction (L 2) • Global Muon Reconstruction (L 3) (Combined with Tracker) Dipanwita Dutta 5 -6 April, 2007, India-CMS Meet, Chandigarh

Simulation of Z 0 + - channel Gen. vs. Rec. Muon from ORCA Dipanwita Dutta Gen Rec p. T (Ge. V) 5 -6 April, 2007, India-CMS Meet, Chandigarh

Gen. – Rec. Muon p. T, Dipanwita Dutta 5 -6 April, 2007, India-CMS Meet, Chandigarh

Reconstruction without background Stand Alone Muon Reconstruction Dipanwita Dutta 5 -6 April, 2007, India-CMS Meet, Chandigarh

Reconstruction with HI Background Stand Alone Muon Reconstruction Dipanwita Dutta 5 -6 April, 2007, India-CMS Meet, Chandigarh

Summary : CMKIN-OSCAR-ORCA • Generation, Simulation and Reconstruction of Z 0 performed with HI background using full CMS simulation package CMKIN, OSCAR, ORCA • Stand Alone Muon Reconstruction show poor mass resolution, Mass width~ 18 Ge. V at Z 0 mass ( m/m~0. 2) • Mass Resolution remains unaltered with HI background using Stand Alone Muon Reconstruction • Global Muon Reconstruction with Tracker: Mass Resolution with HI background to be studied --- No further Support for ORCA Dipanwita Dutta 5 -6 April, 2007, India-CMS Meet, Chandigarh

Reconstruction with CMSSW • CMSSW_1_2_2 downloaded and installed locally at BARC • Muon Reconstruction using CMSSW: Software available for pp, Reconstruction algorithms for HI under development • Involvement of BARC for HI Software transportation to CMSSW is required --Olga • Reconstruction using pp algorithm: Z 0 Generation with PYTHIA using CMSSW Generator Interface -- Simulation+ Digitization--Local + Stand Alone Muon Reconstruction Dipanwita Dutta 5 -6 April, 2007, India-CMS Meet, Chandigarh

Muon Reconstruction with CMSSW PT distribution of Generated and Reconstructed muons Dipanwita Dutta 5 -6 April, 2007, India-CMS Meet, Chandigarh

Reconstructed-Generated PT Difference Dipanwita Dutta 5 -6 April, 2007, India-CMS Meet, Chandigarh

Generated and Reconstructed Invariant Mass m ~ 14 Ge. V Dipanwita Dutta 5 -6 April, 2007, India-CMS Meet, Chandigarh

Part II Real Photon/ Small mass Dilepton Dipanwita Dutta 5 -6 April, 2007, India-CMS Meet, Chandigarh

Dipanwita Dutta 5 -6 April, 2007, India-CMS Meet, Chandigarh

Dipanwita Dutta 5 -6 April, 2007, India-CMS Meet, Chandigarh

Direct Photons at Low p. T – RHIC Result QM 2005: Data consistent with thermal+ NLO p. QCD uncertain at low p. T Gordon and Vogelsang Phys. Rev. D 48, 3136 (1993) Thermal d’Enterria, Perresounko Eur. Phys. J. C 46: 451 -464, 2006 (a) New experimental method for the measurement of Dipanwita Dutta 5 -6 April, 2007, India-CMS Meet, Chandigarh

Future Plan • Involvement in transportation as well as improvement of reconstruction HI softwares from OSCAR, ORCA to CMSSW • Global Muon Reconstruction with Tracker information included in CMSSW for Z 0 + • Simulation for low mass Dimuon/Photon channel-Background muons – (DY and open charm and bottom) • Study the Thermal Dilepton signal (theoretical prediction) and possibility to see the effect of Chemical unsaturation Dipanwita Dutta 5 -6 April, 2007, India-CMS Meet, Chandigarh

Dipanwita Dutta 5 -6 April, 2007, India-CMS Meet, Chandigarh