Observation of a threshold - IHEP

Observationof athreshold enhancementin the pA invariant mass spectrumPhys. Rev. Lett. 93, (2004) Cited 28 timesH.X. Yang(BESCollaboration)IHEPOct.28-Nov.01.2006.Guilin

Observation of a threshold enhancement in the p invariant mass spectrum H.X. Yang (BES Collaboration) IHEP Oct.28 - Nov.01, 2006, Guilin Phys. Rev. Lett. 93, (2004) Cited 28 times

Outline>Introduction>Features of signal and event selection>Reliabilityoftheresult>Summary

Outline ➢Introduction ➢Features of signal and event selection ➢Reliability of the result ➢Summary

Introduction

Introduction

The Beijing Electron PositronColliderL ~ ~5 ×1030 /cm?.s at J/y peakEcm~2-5 GeV

L ~ ~5 1030 /cm2 s at J/ peak Ecm~2-5 GeV The Beijing Electron Positron Collider

BESl DetectorMucn CountersMuon CountersSolenoid CoilSolenoid Coilaisel ShowerCoulMlajnMainDrift ChambertDrift ChamnbeVertexLUMIChamberESCTOFBarrel ShowerCounterMagetVertexYokeChamberMagnet YokeTOFCoumtersSide viewof the BES detectorEndview of theBES detectorVC:TOF:Oxy =100 μm0=180psμ counter:0r=3 cm△E/VE=22%BSC:MDC: oxy= 220 μmoz=5.5cm0.4 TOdE/dx= 8.5 %B field:0g=7.9mr△p/p=1.78%V(1+p2)o, = 3.1 cm

VC: xy = 100 m TOF: T = 180 ps  counter: r= 3 cm MDC: xy = 220 m BSC: E/E= 22 % z = 5.5 cm dE/dx= 8.5 %  = 7.9 mr B field: 0.4 T p/p=1.78%(1+p2 ) z = 3.1 cm BESII Detector