BESIII 粲介子的强子衰变 周晓康 中国科学技术大学 BESIII 粲介(重)子物理研讨会

Outline Summary & prospects Introduction Hadronic decays s(e+e-DD) @ Ecm = 3.773GeV Line shape of s(e+e-DD) around Ecm~3.770 GeV Dalitz Plot Analysis of D+KSp+p0 DD mixing parameter ycp Strong phase difference dKp Strong phase difference for D0/D0KSp+p- Dalitz Plot Analysis of D0KSK+K- PWA analysis of D0K-p+p+p- Observation of SCS decay D+(0)wp+(0) Measurement Br(DS+h’X) and Br(DS+h’r+) Summary & prospects

D hadronic decays Provide better inputs for B physics Open a window into strong final-state interactions Quantum correlated decay: CP asymmetry in mixing and decays Strong phase parametersImpact on g/f3(important for CKM UT)NP

Beijing Electron Positron Collider

The BESIII detector

Charm data @BESIII ~2.92fb-1 y(3770)@3.773GeV ~70pb-1@ 3.745~3.854GeV (22 different Ecm, each 1~8pb-1) D tagging method Single tag (higher eff, larger bg) Double tag (lower eff, smaller bg) ~1.5M D+D-, 2.2M D0D0, 15k Ds+Ds-

s(e+e-DD) @ Ecm = 3.773GeV BESIII got: BESIII preliminary Double tag method ST BESIII got: DT

Line shape of s(e+e-DD) around Ecm~3.770 GeV BESIII preliminary Single BW may not be sufficient to describe DD line shape some introduced an interference in DD final states from non-y(3770) decays(e.g., tails from other cc resonances) Follow the KEDR procedure(PLB711(2012)292) Define Procedure:

Line shape of s(e+e-DD) around Ecm~3.770 GeV(II) BESIII preliminary Single tag method Fit to 2D(DE vs MBC)obtain yieldsobtain ND VDM as example Simultaneously fit to sobs(W) of D0D0 and D+D- Statistical only Consistent with KEDR’s Only determine Geey(3770) ×BF(y(3770)DD)

Dalitz Plot Analysis of D+KSp+p0 PRD89(2014)052001 Partial branching fractions calculated by combining fit fractions with PDG’s D+KSp+p0 branching ratio provide rich information about sub-resonance and strong phase

Strong phase difference dKp PLB734(2014)227 Measuring dKp from rate differences if using external rKp Ignore the mixing effect

Strong phase difference dKp(II) Single tag: fit MBC(CP) Double tag: fit 2D (MBC(CP) vs MBC(Kp)) World best precision Statistical uncertainty dominat In 20fb-1 BESIII data, precision of cosdKp ~0.05 1ab-1 can improve s(f3) due to strong phase to ~1o with external inputs:

DD mixing parameter ycp PLB744(2015)339 CP tag decay rate: Double tag (CP+semileptonic) Neglect high oeder Using CP-tagged semi-leptonic D decays

DD mixing parameter ycp(II) Single tag: fit MBC(CP) Double tag: fit Umiss (~0 for signals) Single tag Compatible with previous measurement Statistically limited Double tag

Strong phase difference for D0/D0KSp+p- Help to reduce systematic/model uncertainty of CKM UT angle g/f3 (GGSZ method PRD68(2003)054018)

Strong phase difference for D0/D0KSp+p-(II) BESIII preliminary Consistent with CLEOc, better stat. err Reduction of contribution to uncertainty of g meas. of 40%(80% for 20fb-1) Improved stat. from B factories could place uncertainty from ci,si contribution @1%

Dalitz Plot Analysis of D0KSK+K- BESIII preliminary Single tag method: 2-D fit on MBC vs. MKs Dalitz Plot Analysis is ongoing Double tag sample, purity: (97.1+-0.3)%

PWA analysis of D0K-p+p+p- BESIII preliminary Golden decay modes Accurate knowledge of substructure  reduce systematic uncertainties Combine with strong phaseimprove g/f3 measurement PRL78(1997)3257 ADS method Consistent with PDG improved the measurement precision a lot

Observation of SCS decay D+(0)wp+(0) BESIII preliminary CLEO-c(281pb-1) did not observe PRL96(2006)081802 Theory predicts ~10-4 due to the destructive interference between color-suppressed diagrams 5.4s PRD81(2010)074021 BESIII first observation： Consistent with theory prediction w helicity angle~cos2q distribution Br(Dhp) consistent previous masurement 4.1s

Measurement Br(DS+h’X) and Br(DS+h’r+) PLB750(2015)466 Br(DS+h’+exclusive)[PDG]=(18.6±2.3)% Br(DS+h’X)=(11.7±1.8)%(CLEO-c @ 4.170GeV, PRD79(2009)112008) In the exclusives Br(DS+h’r+) =(12.5±2.2)%(CLEO-2 @ MY(4S), PRD58(1998)052002) However, CLEO-c reports (@ 4.170GeV, PRD88(2013)032009) Br(DS+h’p+p0) =(5.6±0.5±0.6)% A factorization method predicts Br(DS+h’r+)=(3.0±0.5)%(F.S.Yu, et al, PRD84(2011)074019) Double Tag for Br(DS+h’X) Single Tag for Br(DS+h’r+) Tag side

Measurement Br(DS+h’X) and Br(DS+h’r+)(II) Fit to 2D(M(pph)vs MBC) Consistent with PDG ((11.7±1.7±0.7)%) in 1s DS+h’r Fit to 2D(MBC vs cosqhelicity) DS+h’r = 210±50 events DS+h’p+p0 = -13±56 events Confirm CLEO-c’s result ((5.6±0.5±0.6)%) @ 90%CL

Summary BESIII got many results on charm hadronic decays: Better precision on quantum-correlated measurement @ threshold: for testing CKM, mixing and search for CPV World best precision of dKp Better ci,si for DKsp+p- and ycp than CLEO-c More precise measurement of PWA and Dalitz analysis. Better understanding the substructure of D+KSp+p0, D0KSK+K- First observe D+(0)wp+(0) Measurement of Br(DS+h’X) and Br(DS+h’r+) to confirm CLEO-c’s results Measure s(e+e-DD) and lineshape around 3.770GeV

More hadronic analysis ongoing D0(+)KS/KL X D+K-p+p+p0/D+KSp+p+p- D0wh/hh’/h’p0 D0K-p+h Strong phase in D0Kpp0/ppp0/KKp0 … Coming data taking @4.180GeV for DS+ More interesting/exciting results from BESIII!

Perspectives BESIII will continue to run 6-8 years, will continue play role with the data produced at threshold LHCb runII(2015-2018), 10 times charm data (2Xs(cc)7TeV, 2Xbetter trigger, 50fb-1) will play the key role for charm in next few years. BELLE-II will collect 50 ab-1from e+e- collision Super t-Charm Factory (Russia, China)?

Thanks!

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