Highlights from BESIII. Stephen Lars Olsen, Seoul Nat l Univ. YongPyong, Feb. 27, 2013

Transcription

1 Highlights from BESIII Stephen Lars Olsen, Seoul Nat l Univ. YongPyong, Feb. 27, 2013

2 The Beijing Electron Positron Collider -- BEPCII -- 高能物理研究所 e + e - To Tiananmen Square (~10 km)

3 BEPCII storage rings Beam energy: GeV Peak Luminosity: Design: cm -2 s -1 Achieved:0.65x10 33 cm -2 s -1 Beam energy measurement: Using Compton backscattering technique. Accuracy: de beam /E beam de beam 50 beam m t 3

4 BESIII s 1 st event B 1T TOF 80ps p t p t 1GeV ( de dx ) 6% E g E g 1GeV

5 BESIII Collaboration US (6) Univ. of Hawaii Univ. of Washington Carnegie Mellon Univ. Univ. of Minnesota Univ. of Rochester Univ. of Indiana Europe (12) Germany: Univ. of Bochum, Univ. of Giessen, GSI Univ. of Johannes Gutenberg Helmholtz Ins. In Mainz Russia: JINR Dubna; BINP Novosibirsk Italy: Univ. of Torino,Frascati Lab Netherland:KVI/Univ. of Groningen Sweden: Uppsala Univ. Turkey: Turkey Accelerator Center Pakistan (2) China(30) Univ. of Punjab COMSAT CIIT ~300 members 52 institutions from 11 countries Korea (1) Seoul Nat. Univ. IHEP, CCAST, GUCAS, Shandong Univ., Univ. of Sci. and Tech. of China Zhejiang Univ., Huangshan Coll. Huazhong Normal Univ., Wuhan Univ. Zhengzhou Univ., Henan Normal Univ. Peking Univ., Tsinghua Univ., Zhongshan Univ.,Nankai Univ. Shanxi Univ., Sichuan Univ., Univ. of South China Hunan Univ., Liaoning Univ. Nanjing Univ., Nanjing Normal Univ. Guangxi Normal Univ., Guangxi Univ. Suzhou Univ., Hangzhou Normal Univ. Lanzhou Univ., Henan Sci. and Tech. Univ. Hong Kong Univ., Hong Kong Chinese Univ. Japan (1) Tokyo Univ. 5

6 e + e - annihilations at 2.0 <E cm < 4.6 GeV R-QCD Light hadrons t- thresh h c & c c states Charmonium _ DD thresh _ D s D s thresh XYZ mesons L c L c thresh _ R-QCD v v v v h c _ NN thresh E cm (GeV) Large and diverse suite of physics topics

7 Physics BESIII Light hadron physics -meson & baryon spectroscopy -multiquark states -threshold effects -glueballs & hybrids -two-photon physics -p & n form-factors Charmonium physics: - precision spectroscopy - transitions and decays QCD & t -physics: - precision R-measurement - t decays Charm physics: - semi-leptonic form factors - f D & f D decay consts. s - CKM matrix: V cd, V cs - D 0 -D 0 mixing and CPV - strong phases Precision mass measurements: - t mass - D 0, D + & D s masses XYZ meson physics: -Y(4260) pph c & other decays - searches for new states

8 BESIII data samples 1.2 billion (225M analyzed)

9 Physics BESIII Light hadron physics -meson & baryon spectroscopy -multiquark states -threshold effects -glueballs & hybrids -two-photon physics -p & n form-factors Charmonium physics: - precision spectroscopy - transitions and decays QCD & t -physics: - precision R-measurement - t decays Charm physics: - semi-leptonic form factors - f D & f D decay consts. s - CKM matrix: V cd, V cs - D 0 -D 0 mixing and CPV - strong phases Precision mass measurements: - t mass - D 0, D + & D s masses XYZ meson physics: -Y(4260) pph c decays - searches for new states -,

10 related to? Mesons near the pp threshold BESII years ago -- BESII PRL 91, (2002)

11 BESIII, in 2012, with 5x more data J/y gpp BESIII PRL 108, (2012) Partial Wave Analysis: -J PC = 0 -+ >6.8σ better than other assignments -I=0 FSI (Juelich) improves the fit quality by ~ M= ± 19 model MeV 2m +11 p -40 MeV - G=13±20-33 MeV; < 76 MeV Bf(J/y gx) Bf(X pp)= ( ± 2.3 model ) 10-5 suggests Bf(X pp)~large

12 Some non-observations

13 A pp bound state (baryonium)? There is lots & lots of literature about this possibility deuteron: attractive nuclear force baryonium: attractive force? p n p p loosely bound 3-q & 3-q color singlets with M d =2m p -e loosely bound 3-q & 3-q color singlets with M b =2m p -d?

14 An old idea

15 Fermi & Yang in 1949 (7 years before p discovery): If NN potential is attractive, they could bind to form p-like states.

16 Expectation for pp bound state meson _ below-threshold: p and p annihilate to mesons _ above threshold: X pp ~100% _ I=0, J PC =0 -+ init. state: pp p + p - h is common _ Phys. Rev. C 72, (2005) G.J. Ding and M.L.Yan Comm. Theor. Phys. 42, 844 (2004) C.S. Gao and S.L. Zhu m p +m p

17 J/y g X(1835) g(p + p - h ) BESII -- 8 years ago -- m p +m p M=1833 MeV G 70MeV M(p + p - h ) BESII PRL 95, (2005)

18 X(1835) confirmed at BESIII (+ two new structures with M>2GeV) X(1835) X(1835) consistent with 0 -+ J/y gh p + p - h hp + p - h gp + p - f 1 (1510) two new ones! BESIII consistent with 0 -+ Bkg-subtracted; Eff.-corrected X(1835) PRL 106, (2011) _ X(1835): same mass and J PC as the pp peak, but larger width Resonance M( MeV/c 2 ) G( MeV/c 2 ) Stat.Sig. X(1835) ± ± >20σ X(2120) ± ± σ narrow!! X(2370) ± ± σ 18

19 What are these 2 new structures? way above threshold, but narrow (G<100 MeV) PRD73,014516(2006) Y.Chen et al first distinct resonant structures observed above 2 GeV: -LQCD predicts that the lowest lying -----pseudoscalar glueball: around 2.3 GeV 0 -+ : 2560(35)(120) 2 ++ : 2390(30)(120) -J/y gh p + p - is a good decay channel for finding 0 -+ glueballs. X(2120)/X(2370) possibilities: -pseudoscalar & tensor glueballs? -h/h excited states? Need spin-parity analyses PRD82,074026,2010 J.F. Liu, G.J. Ding and M.L.Yan PRD83:114007,2011 (J.S. Yu, Z.-F. Sun, X. Liu, Q. Zhao)

20 Physics BESIII Light hadron physics -meson & baryon spectroscopy -multiquark states -threshold effects -glueballs & hybrids -two-photon physics -p & n form-factors Charmonium physics: - precision spectroscopy - transitions and decays QCD & t -physics: - precision R-measurement - t decays Charm physics: - semi-leptonic form factors - f D & f D decay consts. s - CKM matrix: V cd, V cs - D 0 -D 0 mixing and CPV - strong phases Precision mass measurements: - t mass - D 0, D + & D s masses XYZ meson physics: -Y(4260) pph c decays - searches for new states -,

21 Precision charmonium mass of the h c charmonium ground state properties of the h c most recently discovered charmonium state M1 transition y gh c first observation p 0 KKp g g

22 h c (1S) The S-wave spin-singlet charmonium ground state, found in 1980 M & G measurements: -J/y radiative transitions: M ~ MeV, G ~ 10 MeV -gg processes / B Kh c : M = ±1.0 MeV/, G = 31.3±1.9 MeV _ gg, pp, B decay Mass y(1s, 2S) gh c width C.L.= C.L.<0.0001

23 y gh c, h c exclusive decays interference with non-resonant background is significant!! KsKp K + K - p 0 p + p - h KsK3p 2K2pp 0 6p Relative phase f values from each mode are consistent within 3, use a common phase value in the simultaneous fit. M: ± 0.5 ± 0.6 MeV G: 30.5 ± 1.0 ± 0.9 MeV : 2.35 ± 0.05 ± 0.04 rad BESIII PRL 108, (2012)

24 Comparison with previous h c results BESIII BESIII Mass width Hyperfine splitting (BESIII alone): M(1S) = ± 0.8 MeV Theorists are happier with this value (earlier result -- ~117 MeV -- was too large for them) LQCD McNeile QWG2011

25 h c ( 1 P 1 ) Spin singlet P wave (S=0, L=1) Potential model: if non-zero P-wave spin-spin interaction, M hf (1P) = M(h c ) - <m(1 3 P J )> 0 where <m(1 3 P J )>= [(M(c c0 )+3M(c c1 )+5M(c c2 )]/9, CLEOc 1 st observed h c in ee y p 0 h c, h c gh c M hf (1P)=0.08±0.18±0.12 MeV/c 2 Consistent with 1P hyperfine splitting = 0. Theoretical prediction: BF(y(2S) p 0 h c ) = ( ) 10-4 BF(h c gh c ) =48% (NRQCD) BF(h c gh c ) =88% (PQCD) Kuang, PR D (2002) BF(h c gh c ) =38% Godfrey and Rosner, PR D (2002)

26 methods for studying the h c only detect the p 0 inclusive (compute M h from kinematics) c Rate Bf ( y p 0 h c ) g p 0 g detect the p 0 & g E 1 -tagged (compute M h from kinematics) c Rate Bf ( y p 0 h c ) Bf (h c gh c ) hadrons detect the p 0, g & all h c X i decay products exclusive (compute M h from 4-C kinematic fit) c Rate Bf ( y p 0 h c ) Bf (h c gh c ) Bf (h c X i )

27 y p 0 h c, h c gh c BESIII BESIII: PRL (2010) Mass = ±0.13±0.18 MeV/c 2 Width = 0.73±0.45±0.28 MeV <1.44 E1 tagged CLEOc: PRL (2008) Mass = ±0.19±0.12 MeV Width: fixed at 0.9 MeV Hyperfine mass splitting M hf (1 1 P)= M(h c ) - <m(1 3 P J )> inclusive BESIII: 0.10±0.13±0.18 MeV/c 2 CLEOc: 0.02± 0.19± 0.13 MeV/c 2 By combining inclusive results with E1-photon tagged results BF(y' p 0 h c ) = (8.4±1.3±1.0) 10-4 Agrees with prediction from Kuang, BF(h c g h c ) = (54.3±6.7±5.2)% Godfrey, Dude et al. 27

28 y p 0 h c, h c gh c, h c exclusive decays BESIII Preliminary Summed distribution 832±35 evts. 16 different h c decay channels Simultaneous fit to p 0 recoiling mass 2 /d.o.f. = 32/46 Mass = ± 0.11 ± 0.15 MeV/c 2 Width = 0.70 ± 0.28 ± 0.25 MeV consistent with BESIII E 1 -tagged results

29 h c lineshape from y p 0 h c, h c gh c Sum of 16 of h C decay modes Background subtracted The h C lineshape in h c gh C is not as distorted as in y gh c decays; the non-resonant interfering bkg is small (non-existent?). Ultimately, this channel will be best suited to determine h c resonance parameters. yesterday s search today s discovery tomorrow s calibration

30 h c lineshape from y p 0 h c, h c gh c Sum of 16 of h C decay modes Background subtracted The h C lineshape in h c gh C is not as distorted as in y gh c decays; the non-resonant interfering bkg is small (non-existent?). Ultimately, this channel will be best suited to determine h c resonance parameters. yesterday s search today s discovery tomorrow s calibration

31 y gh c 1 st observation BESIII c c1 c c2 h c

32 Physics BESIII Light hadron physics -meson & baryon spectroscopy -multiquark states -threshold effects -glueballs & hybrids -two-photon physics -p & n form-factors Charmonium physics: - precision spectroscopy - transitions and decays QCD & t -physics: - precision R-measurement - t decays Charm physics: - semi-leptonic form factors - f D & f D decay consts. s - CKM matrix: V cd, V cs - D 0 -D 0 mixing and CPV - strong phases Precision mass measurements: - t mass - D 0, D + & D s masses XYZ meson physics: -Y(4260) pph c decays - searches for new states -,

33 Charmed meson physics at BESIII e + e - y (3770) DD _ y": Lum dt 2.9 fb -1 ultimate goal : 20 fb -1 Tag a D meson by reconstructing the accompanying D ---and vice versa-- _ In the CM: tag side E D * E * D 1 2 E cm y cm energy difference: E E * E cm 0 signal side beam-energy constr. mass M bc ( 1 2 E cm ) 2 - ( r p i ) 2 produce a beam of D mesons

34 D - tag side σ 2MeV

35 D + m + n signal side only one charged track positively identified as a m + no isolated photons m + n 2 M miss ( 1 2 E cm - E m ) 2 - (- r p tag - r p m ) 2

36 D + m + n backgrounds 377±21 signal evts (from MC) Background determined from data: N b = 48.9 ± 4.8 evts Bf (D + m + ) N D + m + N - Dtag e D + m + ( ) 10-4 Preliminary CLEOc : ( ) 10-2

37 f D determination from CKM fitter BESIII (2.9 fb -1 ) : f D ( ) MeV Preliminary

38 Compare with theory

39 or: V cd determination fromlqcd BESIII (2.9 fb -1 ) : V cd Preliminary

40 V cd results

41 D + l + n prospects D + t + n with current (2.9 fb -1 ) data - Larger signal Bf + larger bkg comparable sensitivity Ultimately D + (& D s ) m + n and t + n with 20 fb -1

42 Physics BESIII Light hadron physics -meson & baryon spectroscopy -multiquark states -threshold effects -glueballs & hybrids -two-photon physics -p & n form-factors Charmonium physics: - precision spectroscopy - transitions and decays QCD & t -physics: - precision R-measurement - t decays Charm physics: - semi-leptonic form factors - f D & f D decay consts. s - CKM matrix: V cd, V cs - D 0 -D 0 mixing and CPV - strong phases Precision mass measurements: - t mass - D 0, D + & D s masses XYZ meson physics: -Y(4260) pph c decays - searches for new states -,

43 Precision mass measurements m t factor of ~3000 disparity lepton universality: Koide s formula: PRD 28, 252 (1983) numerology? m D 0 is M X(3872) above or below m D 0+m D* 0? M X(3872) m D 0 + m D* 0

44 BEPCII beam energy monitor E x

45 Dipole Dipole BEPCII tunnel Shielding wall IR laser steerer

46 Validate at the y peak

47 Results from a 5pb -1 pilot run

48 Data from 30.5 pb -1 Results: m t = 1776.?? will +- be?? MeV open soon ultimate goal, with ~100pb -1 dm t ±0.1 MeV

49 Physics BESIII Light hadron physics -meson & baryon spectroscopy -multiquark states -threshold effects -glueballs & hybrids -two-photon physics -p & n form-factors Charmonium physics: - precision spectroscopy - transitions and decays QCD & t -physics: - precision R-measurement - t decays Charm physics: - semi-leptonic form factors - f D & f D decay consts. s - CKM matrix: V cd, V cs - D 0 -D 0 mixing and CPV - strong phases Precision mass measurements: - t mass - D 0, D + & D s masses XYZ meson physics: -Y(4260) pph c decays - searches for new states -,

50 Y(4260) (& Y(4350)) BESIII BaBar PRL95, (2005) 233 fb -1 Y(4260) ~50pb

51 Y(4260) confirmed -32 by Belle -28 Belle PRL 99,

52 Not seen in e + e - hadrons J.Z.Bai et al (BES), PRL 88, (2006) (e+e- hadrons) (e+e- m+m-) 4260 No sign of Y(4260) D ( * ) D ( * ) peak (Y(4260) p + p - J/y)~50 pb ~3nb BES data G(Y 4260 p + p - J/y) > 90% CL X.H. Mo et al, PL B640, 182 (2006)

53 5S peak position Belle saw a curious p + p - (ns) structure in the bottomonium system (e+e- p + p - ns ) from a cm energy scan Fitted parameters Belle PRD 82, (2010) PDG( 5S ):

54 This is a strong source of Z b mesons ± Belle PRL 99, (2007) (5S) (1S)p + p - (5S) (2S)p + p - (5S) (3S)p + p - M(Υ(1S)π) max M(Υ(2S)π) max M(Υ(3S)π) max Z b (10610) M= MeV G= MeV PDG: M B + M B* = MeV b b B-B* molecule? Z b (10650) M= MeV G= MeV 2M B* = MeV b b B*-B* molecule?

55 reflection? Is the Y(4260) a source of Z c mesons? ± Belle PRL 99, (2007) ~300 Y(4260) evts 2 entries/evt m D +m D* BESIII now has ~1300 Y(4260) p + p - J/y events --& has just accumulated a similar sample of Y(4360) p + p - y evts--

56 We expect to have lots of interesting results on the Y(4260) & Y(4360) for Yongpyong 2014 Please invite us again

57 Concluding remarks BEPCII is operating near design luminosity & BESIII is performing at state-of-art levels pp threshold peak in J/y gpp confirmed; J PC established as 0 -+ ; M 2m p -40 MeV X(1835) p + p - h in J/y gp + p - h confirmed at the same mass & J PC additional narrow (G 80 MeV) p + p - h mass peaks seen at ~2120 & 2375 MeV glueballs? Precision measurements of h c and h c charmonium-state properties are made interference with non-resonant bkg is significant World s largest sample ever of y DD decays already collected precision measurements of f D, V cs and V cd & strong phases in progress corresponding high-statistics D s measurements are planned a t-mass measurement with ~±100keV precision is underway High statistics studies of the Y(4260) and Y(4360) are underway Search for charged Z c molecule-like states _ Excellent detector, excellent machine, interesting program of physics for the next 10 yrs