1. 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

2. Outline Summary & prospects Introduction Hadronic decays
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

3. 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

4. Beijing Electron Positron Collider

5. The BESIII detector

6. Charm data @BESIII ~2.92fb-1 y(3770)@3.773GeV
~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-

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

8. 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:

9. 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)

10. 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

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

12. 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:

13. 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

14. 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

15. 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)

16. 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

17. 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: ( )%

18. 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

19. 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

20. Measurement Br(DS+h’X) and Br(DS+h’r+)
PLB750(2015)466
Br(DS+h’+exclusive)[PDG]=(18.6±2.3)%
GeV, PRD79(2009)112008)
In the exclusives
Br(DS+h’r+) 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

21. 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

22. Summary BESIII got many results on charm hadronic decays:
Better precision on quantum-correlated 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

23. 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 for DS+
More interesting/exciting results from BESIII!

24. Perspectives
BESIII will continue to run 6-8 years, will continue play role with the data produced at threshold
LHCb runII( ), 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)?

25. Thanks!

26. backup