Reach of future  -charm efforts at BESIII Yangheng Zheng Graduate University of Chinese Academy of Sciences NTU May 5 - 9, 2008

May 5-9, 2007Y. FPCP20082Outline  Status of BESIII   -charm physics potentials  Summary

May 5-9, 2007Y. FPCP20083 BEPC II Storage ring RF SR IP Beam energy: GeV Luminosity: 1×10 33 cm -2 s -1 Optimum energy: 1.89 GeV Energy spread: 5.16 ×10 -4 No. of bunches: 93 Bunch length: 1.5 cm Total current: 0.91 A

May 5-9, 2007Y. FPCP20084 Charm productions at BEPCII GeV

May 5-9, 2007Y. FPCP20085 The BESIII Detector Be beam pipe SC magnet, 1T Magnet yoke MDC, 130  m CsI(Tl) calorimeter, GeV TOF, 100ps RPC

May 5-9, 2007Y. FPCP20086 Japan (1) Tokyo University USA (7) University of Hawaii University of Washington Carnegie Mellon University Univ. of Florida Univ. of Minnesota Rensselaer Polytechnic Institute University of Rochester China (24) IHEP, CCAST, GUCAS ， Univ. of Sci. and Tech. of China Shandong Univ., Zhejiang Univ. Huazhong Normal Univ., Wuhan Univ. Zhengzhou Univ., Henan Normal Univ. Peking Univ., Tsinghua Univ., Zhongshan Univ.,Nankai Univ. Shanxi Univ., Sichuan Univ Hunan Univ., Liaoning Univ. Nanjing Univ., Nanjing Normal Univ. Guangxi Normal Univ., Guangxi Univ. Hong Kong University Chinese Univ. of Hong Kong Europe (5) GSI, Germany University of Bochum, Germany University of Giessen, Germany JINR, Dubna, Russia Budker institute of Nuclear Physics Russia “Spectators”: four institutes from Italy Totally 37 institutions now BESIII collaboration

May 5-9, 2007Y. FPCP20087 DAQ + Trigger （ MDC ＋ EMC ＋ TOF+MUC ） Cosmic Ray event  Testing period: Jan. ~ Mar., 2008

May 5-9, 2007Y. FPCP20088 Cosmic ray test status  All systems work  TOF resolution: 110ps achieved  MDC resolution: 130  m achieved  Some problems found and fixed (wrong cabling, Electronics, noisy channels, bad PMT/FED board, etc )  Online data taking is stable and robust,  Most of trigger conditions tested.  2 nd round of cosmic ray test has started on May 8.

May 5-9, 2007Y. FPCP20089 BESIII has been moved to IP (April)!

May 5-9, 2007Y. FPCP BESIII Status  The construction, testing and field measurement of detector super-conducting magnet completed, field measured at 1 tesla and 0.9 tesla.  Finish the installation of all the detector components, MDC, Barrel and endcap TOF, barrel and endcap EMC, all muon chambers, Be beam-pipe.  Commissioned sub-detectors with DAQ, Trigger, and Slow control passed the cosmic ray test.  Software and physics preparation in good shape.

May 5-9, 2007Y. FPCP Next Steps  Commissioning machine and detector together in June 2008;  BESIII yellow book, (specifies the physics goals and potentials, detailed study of certain channels) will be published around June.  To pass the government review in end of 2008,  Lum. ~ 3 x cm -2 s -1 ;  Detector meet certain performances;

May 5-9, 2007Y. FPCP Physics potential at BES-III Yi-Fang Wang Charm 2007

May 5-9, 2007Y. FPCP Charm meson production  Threshold production at 3.773, 4.03, 4.17 GeV  Double Tag techniques: (partial- )reconstruct both D mesons  Charm events at threshold are very clean  Ratio of signal to background is optimum  Lots of systematic uncertainties cancellation while applying double tag method

May 5-9, 2007Y. FPCP D Pairs at Different Experiments D Pairs at Different Experiments 0.2 M 5 M ~120M 500M 700M  (3770) peak  (4S) Peak Background freeHigh statistics ~120 M is expected at BES-III with 4 years’ luminosity. 5 M is expected at CLEO-c until 2008.

May 5-9, 2007Y. FPCP f D+ and challenge of QCD BES-III reaches 2% with 20 fb  1 psi(3770). 7.6% 2.0% CLEO-c: 281 pb -1 PRL 100, (2008)

May 5-9, 2007Y. FPCP f Ds –challenge LQCD f Ds –challenge LQCD 4.0 sigma discrepancy between LQCD and experimental determination in the SM. H.B.Li,J.H.Zou arXiv: % 3.2% See Hewett [hep-ph/ ] & Hou, PRD 48, 2342 (1993). 1.0% CLEO-c, Belle and BaBar: 2.0% 276±6 PRL 100, (2008)

May 5-9, 2007Y. FPCP D mixing at B-factory: D→Kπ  f = K - π +, f = K + π - WS RS δ: strong phase diff. (assume CPV via weak phase only), φ: weak phase  If CP is conserved:  For CPV case: fit two WS distribution separately

May 5-9, 2007Y. FPCP What about Charm factory?  Mixing at threshold  Bad news: no time-dependent information  Good news: Quantum coherence, CP tags  The coherence of two initial D allows simple methods to measure DDbar mixing, strong phase and CP violation  In 20fb -1  (3770) data, we can get  > 4.5x10 5 CP+ tags and > 3.6x10 5 CP- tags  > 10,000 CP+ vs K  double tags and > 10,000 CP- vs K  double tags

May 5-9, 2007Y. FPCP Mixing Parameters Mixing rate Strong phase difference of CF decay and DCS decay, important to measure CP eigenstate lifetime difference CP violation phase CP violation in mixing/decay interference CPV in mixing If CP is conserved,  =0,  =0, y CP =y

May 5-9, 2007Y. FPCP Sensitivities (20 fb -1 )  Mixing parameters  =(x 2 +y 2 )/2 < in K  and Ke channels  Probe y: Δ y CP < 0.7%,  Δ cos  K  < 0.06  CP Violation  Δ A CP ~10 -3 in D + decays (direct CPV),  contributions to  3 /  errors: <2 o (CLEO-c: ~5 o,see Sheldon’s talk) BESIII

May 5-9, 2007Y. FPCP  10 9  (2S) events /year at BES-III Charmonium physics in  (2S) decays  Understand charmonium spectroscopy and charmonium decay dynamics  Hadronic transition (54%)  Radiative transition (28%)  Study of spin-singlets (hc,  c,  c’)  Hadronic decays (15%)  Leptonic decay (2%)  Radiative decays (2%)  Search for rare decays and new phenomena

May 5-9, 2007Y. FPCP M J/  data 5.0  at BESIII at BESII >10  M(  ’  ) GeV/c 2 3  10 9 J/psi events (50 times of BESII)2 years’ data taking X(1835) at BESIII viaExample

May 5-9, 2007Y. FPCP200823Summary  Commissioning of the BESIII detector went smoothly. (Physics data will be taken on early July)  Software and physics analysis preparation is in good shape.  Physics potentials can reach: light hadron, charmonium spectroscopy; open charm physics; energy scan; tau physics, etc.

謝謝！

Backup slides

May 5-9, 2007Y. FPCP Be beam pipe  two Be cylinders (0.8 mm and 0.5 mm thick, 0.8mm gap), cold by paraffine-1  14.6  m gold at the inner surface.  All will be welded together in a couple of days, should be ready for installation in the BESIII before March 20.

May 5-9, 2007Y. FPCP Drift chamber  To measure the momentum of charged particles  Design spec.: Single wire reso. dE/dx reso. CLEO: ~110  m, 5.7% Babar: ~110  m, 6.2% Belle: ~130  m, 5.7% BESIII ~120  m 6 %  R in = 63mm; R out = 810mm; length = 2400 mm  7000 Signal wires: 25(3% Rhenium)  m gold-plated tungsten  Field wires: 110  m Al  Gas: He + C 3 H 8 (60/40)  Momentum 0.5%

May 5-9, 2007Y. FPCP BESIII CsI(Tl) crystal calorimeter  To measure the energy of electromagnetic particles  Barrel: 5280 crystals ， Endcap: 960 crystals  Crystal: (5.2x 5.2 – 6.4 x 6.4) x 28cm 3  Readout: ~13000 Photodiodes, 1cm  2cm,  Energy range ： 20MeV – 2 GeV  position resolution: 6  Tiled angle: theta ~ 1-3 o, phi ~ 1.5 o Babar: BELLE: CLEO: BESIII:

May 5-9, 2007Y. FPCP PID: Time-Of-Flight counters  Double layers at barrel of 88 counters/layer, readout at both ends, endcap each has 48 counters, readout at the inner end. Barrel TOF Endcap TOF High quality plastic scintillator: 2.4 m long, 5cm thick

May 5-9, 2007Y. FPCP CP eigenstate Tags  CP +  K + K  (3.89X10 -3 )   +   (1.38X10 -3 )  Ks  0  0   0  0 (8.4X10 -4 )  K S K S (7.1X10 -4 )   0  0 (3.2x10 -3 )  CP –  K S  0 (0.012)  K s  (3.9X10 -3 )  K S  ' (0.0094)  K S  0 (0.0078)  K s  (0.012)  K S  (4.7X10 -3 ) In 20fb -1  (3770) data, we can get > 4.5x10 5 CP+ tags and > 3.6x10 5 CP  tags With large sample of CP tags, we may improve the measurements of strong phase, probe the direct CP, and other mixing parameters Dalitz Analysis For K s modes: CPV effect of Ks need to be considered! (Prof. Xing/Zhizhong’s suggestion)

May 5-9, 2007Y. FPCP R mix  Golden channel  D 0  K   Semileptonic channel  Ke, K , etc Double tag measurements. Number of R.S. tags at BESIII are expected to be , the sensitivities of R mix — body identical final states are Required in both D hadronic decays experimenttheory

May 5-9, 2007Y. FPCP Strong Phase measurement In 20fb -1  (3770) data, we can get > 10,000 CP+ vs K  double tags > 10,000 CP- vs K  double tags The precision of cos  < 0.06 level is expected at BESIII, Be helpful to improve the precision of  /  3 measurement

May 5-9, 2007Y. FPCP y CP measurements at BESIII Two interesting case with semileptonic tag + CP tags CPV in Mixing is small, Δ =0 In 20fb -1  (3770) data,  10,000 SL+CP(+) tags  10,000 SL+CP(-) tags Δ y CP and Δ A Γ ~ 1% level Applying the inclusive semileptonic tag Can improve the measurements