Leptonic and semileptonic D decays Status and prospects at BESIII Hailong Ma (IHEP&BESIII) Joint BESIII-LHCb workshop in 2018 Feb. 8-9 2018, IHEP, Beijing 1
Main physics goals P or S 1. f D(s), f K(p) (0): better calibrate LQCD 2. V cs(d) : better test on CKM matrix unitarity U Vud Vcd Vus Vcs Vub Vcb 3. Test on lepton flavor universality (LFU) Vtd Vts Vtb 4. Search for new semileptonic decays 2
Samples of D 0() and D s at BESIII D 0() samples 3000 2500 2000 1500 1000 500 0 3000 2000 1000 MARKI DELCO MARKII MARKIII BESII CLEOc BESIII D s samples 2011/2016 4.03/4.14 GeV 4.17 GeV 4.009/4.178 2010-2011 3.773 GeV e i NST 2 N B DD i ST i ST i ST i NDT 2 N B B B m sig N N tot ST D v DD tot DT y sig sig N i i i sig ( NST ST vs.sig / ST ) / i 1 N i 1 K π - D - π - i ST vs. sig N e - i ST 0 BES CLEOc BESIII 3
Single tag D 0() at BESIII e e - y(3770) D D - e e - y(3770) D 0 D 0 D - K p - p - D - K s p - D - K s K - D 0 K p - D 0 K p - p 0 D - K K - p - D - K p - p - p 0 D - p - p - p D 0 K p - p - p D - K s p - p 0 D- K p - p - p - p D - K s p - p - p D 0 K p - p - p p 0 D 0 K p - p 0 p 0 N -tag (170.31 0.34) 10 D 6 largest tag modes give 1.5 M D - tags 4 N D (279.33 0.37) 0 tag 3 largest tag modes give 2.3 M D 0 tags 10 4 Charge conjugations are included 4
Single tag D s at BESIII e e - D s D s- @4.009 GeV e e - D s * D s- c.c.@4.178 GeV N -s D tag 15127 312 0.39 M ST D s- mesons 5
Measurement of D l v 818 pb -1 at y(3770) (2004-2008) PRD78(2008)052003 2.93 fb -1 data@3.773 GeV PRD89(2014)051104R BESIII result has been re-calculated with the latest LQCD calculation 409 21 K L p 150 m vt v CLEO BESIII B D mn (3.82 0.32 0.09) 10-4 B D mn (3.71 0.19 0.06) 10-4 f D =205.8 7.5 2.5 MeV f D (203.2 5.3 1.8) MeV V cd 0.2210 0.0058 0.0047 20 fb -1 data help to reduce the uncertainty of f D to 1% 6
Search for D t v 4s B[D t n] (1.20 0.24 stat. ) 10-3 SM prediction: 2.66 BESIII: 3.21 0.64 20 fb -1 data help to reduce the uncertainty to 8% 7
Previous measurements of D s l v In the past 30 years, D s l v has been studied by WA75, CLEOII, E653, BESI, L3, OPAL, ALPHA, CLEO-c, BELLE, Babar D s * D s-, 600 pb -1 @ 4.17 GeV [697 l v] PRD79(2009)052001 Belle, 913 fb -1 at 10.58 GeV [2698 l v] Babar, 521 fb -1 at 10.58 GeV [1023 l v] JHEP1309(2013)129 PRD82(2010)091103 f Ds =263.3 8.2 1.9 MeV PRD79(2009)052002 f Ds =252.2 11.1 5.2 MeV PRD80(2009)112004 f Ds =257.8 13.3 5.2 MeV f Ds =255.5 4.2 5.1 MeV f Ds =258.6 6.4 7.5 MeV 8
Measurement of D s l v 0.482 fb -1 data @4.009 GeV PRD94(2016)072004 3.19 fb -1 data @4.178 GeV Use m counter to suppress background N[D s m v]=1135.0 33.1 f Ds (241.0 16.3 6.6) MeV f Ds V cs =242.5 3.5 3.7 MeV Uncertainty of f Ds with m/tv is expected to reach 1.5% with 3.19 fb -1 data 9
Previous measurements of D K(p)l v In the past 30 years, studies of D K(p)l v were made by MARKIII, E691, CLEO, CLEOII, BESII, FOCUS, BELLE, Babar and CLEO-c BELLE, 282 fb -1 at 10.58 GeV Babar, 75 fb -1 at 10.58 GeV PRD76(2007)052005 D 0 K - e v PRL97(2006)061804 Babar, 347.2 fb -1 at 10.58 GeV 2004-2009, CLEO-c, 818 pb -1 at y D 0 p - e v PRD91(2015)052022 PRD80(2009)032005 Before 2010, the LQCD calculated f D K(p) (0) precision is at 10% level, thus limiting V cs(d) measurement 10
Progress in LQCD calculations Taking from Aida X. EI-Khadra s talk at Beauty2014 9
Analysis of D 0 K(p) - e v B D K (3.505 0.014 0 - e v PRD92(2015)072012 0.033)% B (0.2950 0.0041 0 - D p e v 0.0026)% Different parameterizations of form factor Single pole Modified pole ISGW2 Series expansion 12
Analysis of D K L e v PRD92(2015)112008 Simultaneous fit to event density I(q 2 ) with 2-par. series Form Factor B(D K L e v) =(4.482 0.027 0.103)% A CP D KLev =(-0.59 0.60 1.50)% D K L ev is measured for the first time f K (0) V cs =0.728 0.006 0.011 13
Analysis of D K(p) 0 e v PRD96(2017)012002 B[ D 0 K e v ] (8.604 0.056 0.151)% B[ D 0 p e v] (3.631 0.075 0.051) 10-3 14
Comparisons of f D K(p) (0) 15
Measurements of V cs(d) Taken from PDG, and the SL method suffers about 2.4% error from LQCD 16
Test of LFU in D 0() pl v decays Evidence of LFV at 4s in (*) (*) B(B D tn ) R( D ) (*) B(B D ln ) B( D B( D p p 0( ) -(0) 0( ) R LU 0( ) -(0) B PDG16 : R 0 LU m v) ~ 0.97 e v) 0.82 0.08 (~ 2.0s ) 2276 63 D 0 p - m v p 0 p p - K 0 p p - Other Evidence of LFV at 2.6s in FCNC decays B K m m - /K e e - 1340 42 D p 0 m v p 0 p p 0 K 0 p p 0 Other LHCb, PRL113(2014)151601 B[D 0 p - m v] = (0.267 0.007 0.007)% B[D p 0 m v] = (0.342 0.011 0.010)% 17
Observation of D Se v Explore the nontrivial internal structure of light hadron mesons, traditional qq states, tetra quark system. With chiral unitarity approach in the coupled channels, BF is predicted to be order of 5(6) 10-5 for D 0() decays Improve understanding of classification of light scalar mesons R=1(3) if traditional qq (tetra quark) system 18
Form factors of D Ve v 19
PWA of D K - p e v PRD94(2016)032001 Fractions with >5s significance Model independent S-wave phase measurement Properties of different Kp (non-) resonant amplitudes q 2 dependent form factors in D K *0 (892)e v M V/A is expected to M D*(1-/) Model independent form factors 20
Study of D we v and search for D fe v PRD92(2015)071101(RC) D we v D fe v B[D we v]=(1.63 0.11 0.08) 10-3 B[D fe v]<1.3 10-5 at 90% C.L. Better precision or sensitivity Amplitude analysis of D we v is performed for the first time r V =V(0)/A 1 (0)=1.24 0.09 0.06 r 2 =A 2 (0)/A 1 (0)=1.06 0.15 0.05 21
Studies of D s K (*)0 e v at 4.178 GeV BESIII preliminary D s K 0 e n e N obs =117.2 13.9 BESIII preliminary D s K* 0 e n e N obs =155.0 17.2 Fit background via inclusive MC 3.2 fb -1 data@4.178 GeV Data M Dssideband B[D s K 0 e n e ] =(3.25 0.38 stat 0.14 syst ) 10-3 B[D s K* 0 e n e ]=(2.38 0.26 stat 0.12 syst ) 10-3 (3.9 0.9) 10-3 [PDG17] (1.8 0.4) 10-3 [PDG17] Four dimensional un-binned likelihood fit is performed. K* paramters are fixed Taking V CKMfitter cd as input r V =1.67 0.34 0.16 r 2 =0.77 0.28 0.07 22
Summary With ~3/3 fb -1 data taken at 3.773/4.178 GeV by BESIII, the leptonic decay of D (s) l v and some semi-leptonic D decays, and improved measurements of V cs(d), decay constants, form factors have been obtained More results are expected in the near future D s t v, f Ds and V cs D s h ( ) e v, form factors and V cs D s K K - /p p - e v, form factors D 0 K - m v, f K(q 2 ) and V cs D K 1 (1270)e v D (s) 0() Xe v All Cabibbo-suppressed D 0() decays and D s decays are restricted by the limited data 23
Prospects at BESIII With 20/6 fb -1 data taken at 3.773/4.178 GeV, some elementary constants can be further improved Systematic error Statistical error ~3 fb -1 Expected with 20/6 fb -1 Df D /f D 0.9% 2.6% 0.5% Df Ds /f Ds 1.5% 1.5% ~1% Df D K /f D K 0.5% 0.4% 0.15% Df D p /f D p 0.7% 1.3% 0.5% V cs Ds lv 1.5% 1.5% ~1% V cs D0 K-ev 2.5%(2.4% LQCD ) 0.4% 0.15% V cd D mv 0.9% 2.6% ~1% V cd D0 p-ev 4.5%(4.4% LQCD ) 1.3% 0.5% Only D s m v is considered. The contribution of D s t v will be comparable or slightly better than D s m v Once LQCD uncertainties reach <1% level, the V cs(d) will be much improved More or improved measurements of form factors of semileptonic decays, containing scalar or axial-vector meson, which are now statistically limited 24
Thank you! 25
BEPCII collider Beam energy: 1.0-2.3 GeV Optimum energy: 1.89 GeV Designed luminosity: 1.00 10 33 cm -2 s -1 Data taken from: 2009 Achieved luminosity: 1.00 10 33 cm -2 s -1 26
BESIII detector <70 ps endcap updated in 2015 27
Improved BF for D K 0 m v With 6 dominant D - single tag EPJC76(2016)369 K 0 p p - 16516±130 Simultaneous fits K 0 p 0 p 0 4198±33 Taking B[D 0 K - m v] and B[D K 0 e v] from the PDG as input [ D [ D [ D 0 [ D K K K - K m v] 0 0 m v] m v] 0 e v] 0.963 0.044 0.988 0.033 Support isospin conservation in these two decays within errors Consistent with theory prediction 0.97 within error 28
Absolute BF for D K 0 e v via K 0 p 0 p 0 With 6 dominant D - single tag CPC40(2016)113001 5013±78 Taking t D, t D0, B[D 0 K - e v] and B[D K 0 e v] from the PDG as input [ D [ D 0 K K - 0 e e v] v] 0.969 0.025 Agrees with isospin conservation within 1.2s 29
Measurements of BFs of D s h ( ) e v Benefit the understanding of the source of difference of inclusive decay rates of D 0() and D s Complementary information to understand h-h mixing 482 pb -1 data@4.009 GeV, PRD94(2016)112003 CLEOII 95 CLEOc09 CLEOc15 30
Measurements of BFs of D s f/h ( ) m v 482 pb -1 data@4.009 GeV, PRD97(2018)012006 fe v fm v The ratios of BFs hm v h m v [ Ds [ D s [ Ds [ D s fm v] 0.86 0.29 fe v] hm v] 1.05 0.24 he v] [ Ds [ D s h' m v] h' e v] 1.14 0.68 BFs of semi-muonic decays are measured for the first time 31