muon trigger and physical processes with hard muons at a collider experiment

Muon Trigger Muon Trigger and Physical Processes and Physical Processes

with Hard Muons with Hard Muons at a Collider Experimentat a Collider Experiment

V. PalichikJoint Institute for Nuclear Research

Dubna

NEC’2003

Varna, Bulgaria

15 September, 2003

V. Palichik NEC’2003 Varna, Bulgaria 15 September, 2003

Study of Processes with Hard MuonsStudy of Processes with Hard Muons

2007: start of 14 TeV LHC

An interest to An interest to search heavy resonances (search heavy resonances (ZZ, W, W, g, gkkkk) ) in TeV region:in TeV region:

C.-E.Wulz “Z at LHC”, CMS-TN/93-107.

P.Traczyk, G.Wrochna “Search for Randall-Sundrum Gravition Excitations in the CMS Experiment”, CMS Note 2002/003.

C.Alexa “Prospects for Exotic Physics at the LHC”, ATL-CONF-2001-005.

D.R.Tovey “Searches for New Physics at the LHC”, ATL-CONF-2002-005.

I.Golutvin, P.Moissenz, V.Palichik, M.Savina, S.Shmatov “Search for

TeV-scale bosons in the +- decay channel in CMS”, reported at Conf. ”Physics at LHC”, Prague, July, 2003.


An eхаmple of di-muon event (Pt of muons ~ 1 TeV)


Identification and reconstruction of TeV Identification and reconstruction of TeV muons on L1 and L2 trigger levelsmuons on L1 and L2 trigger levels

L1 reconstruction of TeV muons in CSCs:L1 reconstruction of TeV muons in CSCs:

Pt, GeV

N events

Pt ( L1 )

The principle of working of a Cathode Strip The principle of working of a Cathode Strip ChamberChamber


Cathode Local Charge Track (CLCT) in CSC Cathode Local Charge Track (CLCT) in CSC


N layerN layer ADC

11

22

33

44

55

66N strip

1/21/2–strip algorithm –strip algorithm on 6 layerson 6 layers

CLCT RMS accuracy CLCT RMS accuracy of 0.15 strip widthof 0.15 strip width

Level-2 Algorithm for Muon ReconstructionLevel-2 Algorithm for Muon Reconstruction


L1 muon trigger data provides (eta-phi)-L1 muon trigger data provides (eta-phi)-region for muon track searching;region for muon track searching;

track-segments building in a given (eta-track-segments building in a given (eta-phi)-region for each chamber;phi)-region for each chamber;

L2 trajectory seeding (position and L2 trajectory seeding (position and momentum) on a base of L1 muon tracks;momentum) on a base of L1 muon tracks;

track reconstruction using Kalman filter track reconstruction using Kalman filter technique.technique.

An example of L1&L2 reconstruction An example of L1&L2 reconstruction of a simulated 1 TeV muon event in CSCsof a simulated 1 TeV muon event in CSCs


Drawn by Ivan Belotelov, JINR

cm

rad

z - projection

z - projection

Z, cm

Z, cm

generated muon

* CLCTs

L1 reconstruction

L2 reconstruction

CSC hits

CSC track segments

CSC hits used for L2 reco

++ Kalman filter propagation states

Standard object-oriented reconstruction

Pt(gen)=1000 GeV

Pt(L1)= 6 GeV

Pt(L2)= 5 GeV

Reconstructed Pt (L2) distribution Reconstructed Pt (L2) distribution for 1 TeV muons for 1 TeV muons


Standard object-oriented reconstruction

The results obtained in cooperation with Ivan Belotelov

Pt, GeV Pt, GeV

Modification of L2 reconstruction algorithm Modification of L2 reconstruction algorithm for TeV muons in CSCsfor TeV muons in CSCs


The modifications of the algorithm have been The modifications of the algorithm have been created in cooperation with Ivan Belotelovcreated in cooperation with Ivan Belotelov

1. The algorithm of track segment building has been improved with taking into account the contamination of muon measurements by a secondary electromagnetic accompaniment.

2. New L2 trajectory seeding on a base of the best track-segment selection (on criteria) in a wide L1 -region has been proposed.

An example of L1&L2 reconstruction An example of L1&L2 reconstruction of a simulated 1 TeV muon event in CSCsof a simulated 1 TeV muon event in CSCs


Drawn by Ivan Belotelov, JINR

generated muon

* CLCTs

L1 reconstruction

L2 reconstruction

CSC hits

CSC track segments

CSC hits used for L2 reco

++ Kalman filter propagation states

Modified object-oriented reconstruction

Pt(gen)=1000 GeV

Pt(L1)= 6 GeV

Pt(L2)= 1300 GeV

rad

cm

Z, cm

Z, cm

z - projection

z - projection

Reconstructed Pt (L2) distribution Reconstructed Pt (L2) distribution for 1 TeV muons for 1 TeV muons


Modified object-oriented reconstruction

The results obtained in cooperation with Ivan Belotelov

Pt, GeV Pt, GeV

ppTT of reconstructed muons in CMS tracking systemof reconstructed muons in CMS tracking system

barrel and endcaps || 2.1 dPt/Pt distributions

Z (1200)

Z (500)

red lines are muon pT distributions generated by PYTHIA

blue lines are reconstructed ones

fitted by Gauss


ZZ mass reconstruction mass reconstruction in CMS in CMS

Invariant mass of muon pairs from Pythia

Full reconstruction of invariant mass

Z (500)

Z (1200)


SummarySummaryA transverse momentum of TeV muons at A transverse momentum of TeV muons at L2 trigger level is significantly L2 trigger level is significantly underestimated due to a hard underestimated due to a hard contamination of muon measurements by a contamination of muon measurements by a secondary electromagnetic accompaniment. secondary electromagnetic accompaniment.

Tuned track segment building and new L2 Tuned track segment building and new L2 trajectory seeding algorithm on a base of trajectory seeding algorithm on a base of the best track-segments has been proposed. the best track-segments has been proposed. It essentially improves L2 Pt reconstruction It essentially improves L2 Pt reconstruction in muon system for TeV muons.in muon system for TeV muons.

Mass resolution of 5-6% for new gauge Mass resolution of 5-6% for new gauge boson resonances Zboson resonances Z (500) and Z (500) and Z (1200) in (1200) in CMS has been obtained (with a natural CMS has been obtained (with a natural width of 2-3width of 2-3%).%).


muon trigger and physical processes with hard muons at a collider experiment

Documents