北京谱仪实验（ bes ）

北京谱仪实验（ BES ）

沈肖雁

中国科学院高能物理研究所[email protected]

2011 年 11 月 4 日（中国科学技术大学）

目录粒子物理简介北京谱仪实验上的物理

• 轻强子谱的研究• 粲偶素产生与衰变性质的研究• CKM 矩阵元的精确测量• R 值的精确测量和 QCD 研究• 物理• 新物理的寻找

北京谱仪实验结果举例

3

1947 年前，我们只知道很少的“粒子”，如质子、中子、电子、 μ 子等，人们认为这些粒子就是构成物质的最小单元，称之为“基本粒子”。此后，在宇宙线实验和粒子加速器实验中发现了大量的粒子：π ， π0 ， K ， K0 ， K0 ， Λ ，， Ξ ， Δ … 约几百种。有的寿命很短，产生出来很快就蜕变成别的粒子。

问题：是不是这几百种粒子都是 “基本”的？

王淦昌发现反西格玛负超子

4

1963 年 , 根据大量的实验数据 , 盖尔曼等猜测这些粒子具有内部结构 , 并给出了计算这些粒子质量的公式

盖尔曼的夸克模型：共有三种夸克 u,d,s

60 年代中期 , 中国的粒子物理学家曾提出了层子模型

介子由（ qq ）构成重子由（ qqq ）构成

+ (ud )

质子 (uud) M. Gell-Mann

1969 Nobel

5

质量公式预言 m-=1670 MeV

实验 m- =1672.45 0.29 MeV

s

I3

K+(us)K0(ds)

-(u d)+(ud)

K-(su)

0

K0(sd)

s

I3

K*+K*0

-

K*-

+

K*0

0

s

I3

n(udd)

p(uud)

-(dds)0 (uds)0

+ (uus)

-(dss) 0(uss)(sss)

△0△- △+ △++

0*- *+

(ddd) (udd) (uud) (uuu)

(dds) (uds) (uus)

*- *0

(uss)(dss)

-

自旋为 0

0 =uu-dd

2

自旋为 1

6

建立夸克模型的关键实验 :电子轰击质子 (1972)

质子并不是一个几何点。它有大小，其半径 10-13cm ，电荷就分布在这样一个小空间范围质子内部分布着大量的点电荷定量分析表明 , 质子是由三个夸克组成

e

e

Jerome I. Friedman 等， 1992 Nobel

7

几年后，实验上发现 charm 夸克！

1974 年——丁肇中， B. Richter 发现 J/ 粒子这个介子寿命非常长。 → charm 夸克 (c) mc ~ 1.5GeV

J/Ψ 由 (cc ) 构成。

November revolution

Discovery of the J/ψ

PRL33, 1404 (1974) PRL33, 1406 (1974) PRL33, 1408 (1974)

BNL SLAC

ADONEconfirmed!

“November Revolution of Particle Physics!”

Charm quark was proposed in 1964, first application in 1970!

Design:Maximum Ecm~3 GeV!

Discovery of the ψ(2S)

PRL33, 1453 (1974)

SLAC

PRL34, 365 (1975) PRL34, 369 (1975)

From then on, there is a new field in HEP: Charmonium Physics.

1977 年—— L.Lederman 发现 ( 9.5GeV )

　　　　 → Beauty (Bottom) (b) mb ~ 5GeV

(9.5) 由 (bb ) 构成

1994 年—— Fermilab. CDF 组发现 Top 夸克 (t)

mt ~ 176GeV

11

u

d

c

s

t

b

e m t

ne nt

电荷

+2/3

-1/3

0

-1

夸克 ( q )

轻子 ( l )

我们知道的构成物质世界的最“基本” 粒子从轻到重

m

12

粒子物理要解决的基本问题 :

2. 研究物质之间的相互作用物质之间已知的相互作用

• 引力相互作用• 电磁相互作用• 弱相互作用• 强相互作用

相互作用的传播• 所有的相互作用均通过传播子以光速传播• 引力 : 质量 , 引力子 (?)• 电磁力 : 电荷 , 光子

宏观 ( 经典 ) 作用力

微观 ( 量子 ) 作用力

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弱相互作用原子核衰变 n p + e + n 30 年代 , Fermi 提出了弱作用理论弱作用的特性 :

• 宇称不守恒 (P) 只有左旋中微子• 电荷反演不守恒 (C)• CP 不守恒

Enrico Fermi1937 nobel

Chen Ning Yang Tsung-Dao Lee1957 nobel

14

弱电统一弱作用本质上与电磁作用是同一种力 , 就象电与磁是同一种

力 , 均可由麦克斯韦方程描述一样弱电统一理论 70 年代由温伯格等提出 , 其基础是杨振宁与

Mills 提出的杨 - Mills规范场理论 Rubbia 等 80 年代通过实验证实了弱电统一理论问题：

• 弱作用 : 弱荷 , W, Z0

• W, Z0 有质量，如何传播相互作用？解决办法：

• W, Z0 与一种叫做 Higgs 的粒子相互作用• 寻找 Higgs 粒子是目前粒子物理研究的首要任务 Carlo Rubbia

1984 nobel

15

强相互作用 : 量子色动力学

描述强相互作用的理论。强子（参与强相互作用的粒子）由夸克组成。夸克与胶子是有颜色的（色荷）。 “ 夸克渐进自由”为理论基础。

强相互作用的渐近自由理论已被实验所证实。

物质结构：物质由三代轻子与夸克构成 :

自然界中四种相互作用中的三种 :

粒子物理－标准模型理论

e

e

bsd

tcu

｝电弱统一理论 (EW)

粒子物理是研究物质深层结构和相互作用的基础学科：

始终处于科学发展的最前沿

电磁作用弱作用

量子色动力学 (QCD)强作用17

标准模型（ EW＋QCD ）的检验

以在欧洲核子物理中心（ CERN ）的 LEP 对撞机上的四个实验为主，对标准模型，尤其是弱电理论进行了大量精确检验，证明了标准模型的巨大成功。

标准模型中的 Higgs 粒子的寻找是 LHC 实验主要物理目标之一。

量子色动力学（ QCD ）• 在高能（ >10 GeV) 下预言的“渐近自由”现象

已被大量实验所证实。“渐近自由” 的发现获得 2004 年 Nobel 奖。

• 低能下 ( <3GeV) 尚有待进一步实验检验，尤其是有许多重大问题亟待实验回答：

19

低能下如何描述强相互作用系统？自然界是否存在新型强子和新的物质形态？

20

Linac Storage ring

BES

BSRF

Beijing Electron Positron Collider (BEPC) at IHEP

21

BES

1-2.3GeV e+ e- collisions produce charmonium states （ J/ ， (2S) ， cJ and (3770) etc.), charm mesons and lepton.

beam energy: 1.0 – 2.3(2.5) GeV

Physics goal

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（ BEPC/BES ）

2001 年初，美国的 CESR 将它的能量从 B 介子能区（束流能量 5.3 GeV ）降到粲能区。 2008 年 4 月

停！美国和日本的 B 介子工厂也在研究粲物理（停机） BELLE-II 正在建造，意大利 SuperFlavor

Factory 已经立项

正在欧洲投入巨资建造的 PANDA 实验也以粲物理研究为首要物理目标之一。 (2017 年后建成）

正在运行的北京正负电子对撞机 (BEPCII) / 北京谱仪 (BESIII) 是近年内唯一运行在 - 粲能区的实验装置！

- 粲物理是国际高能物理实验研究竞争的热点之一

22

We are unique now in -charm region

In transition region between pQCD and non-pQCD.

23

The Y’s are here!

From PDG

Physics at BEPC/BES

In the 1990s, there was discussion of the future. The conclusion was to continue tau-charm physics with a major upgrade of the accelerator and detector (BEPCII/BESIII). Officially approved in 2003.

The physics window is precision charm physics and the search for new physics.

• High statistics: high luminosity machine + high quality detector.

• Small systematic error: high quality detector.

BEPCII/BESIII

BEPCII Storage Ring: Double-ring RFRF SR

IP

22 m

rad

2. 5m8ns

1. 5cm

0.1cm

Beam energy: 1.0-2 .3GeVLuminosity: 1×1033 cm-2s-1

Optimum energy: 1.89 GeVEnergy spread: 5.16 ×10-4

No. of bunches: 93Bunch length: 1.5 cmTotal current: 0.91 ASR mode: 0.25A @ 2.5 GeV

北京谱仪探测器（ BESIII)

Japan (1)Tokyo Univ.

US (6)Univ. of Hawaii

Univ. of WashingtonCarnegie Mellon Univ.

Univ. of Minnesota Univ. of Rochester

Univ. of Indiana

Europe (10)Germany: Univ. of Bochum,

Univ. of Giessen, GSI Univ. ofJohannes Gutenberg

Helmholtz Ins. In MainzRussia: JINR Dubna; BINP Novosibirsk

Italy: Univ. of Torino ， Frascati LabNetherland ： KVI/Univ. of Groningen

China(29)IHEP, CCAST, 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 UnivHunan 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.

Korea (1)Seoul Nat. Univ.

Pakistan (1)Univ. of Punjab

BESIII Collaborationhttp://bes3.ihep.ac.cn ~300 members from 48 institution of 9 counties

28

http://bes3.ihep.ac.cn/

29

Study of Light hadron spectroscopy

search for non-qq or non-qqq states meson spectroscopy baryon spectroscopy

Study of the production and decay mechanisms of charmonium states: J/, (2S), C(1S), C{0,1,2} , C(2S), hC(1P1), (3770), etc. New Charmonium states above open charm threshold.

Precise measurement of R values, mass, ...

Precise measurement of CKM matrix

Search for DDbar mixing, CP violation, etc.

Physics Topics at BES

arXiv: 0809.1869

New forms of hadrons

Hadrons consist of 2 or 3 quarks ： Naive Quark Model ：

QCD predicts the new forms of hadrons:• Multi-quark states ： Number of quarks >＝ 4 • Hybrids ： qqg ， qqqg …• Glueballs ： gg ， ggg …

Meson （ q q ）

Baryon （ q q q ）

31

Study of the spectroscopy – a way of understanding the internal structure

glueball spectrum from LQCD

Y. Chen et al., PRD 73 (2006) 014516 31

Motivation: Establish spectrum of light hadrons Search for non-conventional hadrons Understand how hadrons are formed

Why at a -charm collider ? Gluon rich Clean environment JPC filter , isospin filter

32


search for non-qqbar or non-qqq states meson spectroscopy baryon spectroscopy


Precise measurement of R values




arXiv: 0809.1869

Charmonium physics What to study ?

• Production, decays, transition, spectrum

Examples of interesting/long standing issues:

• rp puzzle• Missing states ?• Mixing states ?• New states above open

charm thre.(X,Y,Z,…)

X(3872)

粲偶素谱??

34








arXiv: 0809.1869

35

R : one of the most important and fundamental quantities in particle physics.

R -

e+

e-

+

h a d ro n s-e

e+

q-

q

f la v o rc o lo r

= Qf2

lowestorder

R measurement

Why precise R important?

Essential for precise testsof SM.

the global fit of Higgs mass anomalous magnetic

moment from g-2

36








arXiv: 0809.1869

Precise measurement of CKM elements-- Test EW theory

b

s

d

VVV

VVV

VVV

b

s

d

tbtstd

cbcscd

ubusud

'

'

' CKM matrix

Three generations of quark? Unitary matrix?

5% precision 10% precision

Expect precision < 2% at BESIII Improve the precision at BESIII

Precision measurement of CKM matrix elements --a precise test to SM model New physics beyond SM?37

CKM matrix elements are fundamental SM parameters that describe the mixing of quark fields due to weak interaction.

Decay constants vs LQCD

2.3 difference for fDs. Real ?BESIII may resolve this issue, reach the precision of LQCD.

fD

fDs

CP violation is regarded as the origin of asymmetry of the matter and anti-matter.

CP violation predicted by theoretical models is not big enough to describe the asymmetry.

CP violation is observed in K and B decays, but has never been in charm sector.

CP violation and mixing

0

0

00 | | DDCP

00 DD

e+e- (3770) D0D0

At BESIII, the sensitivity of the mixing rate: 1.5 10-4

mixing : a good place to search for CP violation

In SM, the mixing is very small.

39

00 DD

Mar. 2008: first full cosmic-ray event• April 30, 2008: Move the BESIII to IP• July 19, 2008: First e+e- collision event in BESIII• Nov. 2008: ~ 14M (2S) events • April 14, 2009: ~106M (2S) events • May 30, 2009: ~42 pb-1 at continuum (3.65 GeV)• July 28, 2009: ~226M J/ events • Aug. – Dec., 2009: summer maintenance, SR run• Jan. 2010 – April 2011: ~2900 pb-1 at (3770)• May 2011: ~ 500 pb-1 at (4040) for Ds and XYZ spectroscopy

BESIII commissioning and data taking milestones

Peak Lumi. : 0.651033cm-2s-1 Designed: 1033cm-2s-1

41

• BESIII data-taking plans– 2012: 1 billon J/, 0.7~1 billon ’– 2013: @4170 MeV DS physics; R scan – 2014: R scan– (3770) 5-10 fb-1

First collision event on July 19, 2008

e+e- (3770) D0D0

Reso. 135 mm

σP=11.0 MeV/c

MDC performance & data/MC

Double-layer TOF

Barrel Double Layer

Z (cm)

Time Resolution (ps)

Time Resolution

（ ps ）Design Target

Bhabha Dimu

Barrel Single Layer

100~110 98.0 95.3

Barrel Double Layer

80~90 78.9 76.3

Endcap 110~120 136.4 95.0

EMC (CsI(Tl))Barrel energy resolution

energy resolution for Bhabha events Position resolution for Bhabha

4.4 mm

energy deposit for e+e-gg

Inclusive photon spectrum of (2S)

c2c1

co

c1,2 J/

c

BESIII preliminary

Excellent photon resolution

Results from BESIII

Confirm BESII results threshold enhancement in pp, X(1835), …

New improved measurements hc, c, cJ, , …

New observations cJ decays hc decays Light hadrons, …

MKIII CBAL BESI BESII CLEO BESIII0

20406080

100120140160180200（ 106 ）

J/(2S)

48

Charmonium stateshc , hc(1S), hc(2S)

49

hc(1P1)• Spin singlet P wave (S=0, L=1)

• Potential model: if non-vanishing spin-spin interaction, DMhf(1P) = M(hc) - <m(1 3PJ)> ≠0 where <m(1 3PJ)>= [(M(cc0)+3M(cc1)+5M(cc2)]/9 • E835 found evidence for hc in pphcc

• CLEOc observed hc in ee’0hc, hc c

DMhf(1P)=0.08±0.18±0.12 MeV/c2

Consistent to 1P hyperfine splitting of 0.

PRL 101 182003 (2008)

Theoretical prediction:BF((2S)0hc) = (0.4-1.3)×10-4

BF(hcc) =48% (NRQCD)BF(hcc) =88% (PQCD) Kuang, PR D65 094024 (2002)

BF(hcc) =38% Godfrey and Rosner, PR D66 014012(2002)

_

50

y(2S) p 0hc , hcghc at BESIII

BESIII: PRL 104 132002 (2010)

Mass = 3525.40±0.13±0.18 MeV/c2

Width = 0.73±0.45±0.28 MeV

<1.44 MeV @90%

CLEOc: PRL 101 182003 (2008)

Mass = 3525.28±0.19±0.12 MeV

Width: fixed at 0.9 MeV

Hyperfine mass splittingDMhf(1P)= M(hc ) - <m(1 3PJ )>

BESIII: 0.10±0.13±0.18 MeV/c2

CLEOc: 0.02±0.19±0.13 MeV/c2

By combining inclusive results with E1-photon tagged results

BF(' 0 hc ) = (8.4±1.3±1.0) ×10-4 Agree with prediction from Kuang,BF(hc c) = (54.3±6.7±5.2)% Godgrey, Dude et al.

inclusive

E1 tagged

BESIII

51

y’ p 0hc, hcghc , hc exclusive decays

Simultaneous fit to p0 recoiling mass2/d.o.f. = 32/46Mass = 3525.31±0.11±0.15 MeV/c2

Width = 0.70±0.28±0.25 MeV

Consistent with BESIII inclusive results Mass = 3525.40±0.13±0.18 MeV/c2

Width = 0.73±0.45±0.28 MeV

CLEOc exclusive results Mass =3525.21±0.27±0.14 MeV/c2

evts. =136±14

Summed distribution

832±35 evts.

BESIII Preliminary

BESIII: PRL 104 132002 (2010)CLEOc: PRL 101 182003 (2008)

52

hc(1S) The lowest lying S-wave spin singlet charmonium, discovered in

1980 by MarkII Parameters: J/y radiative transition: M ~ 2978.0MeV/c2, G ~ 10MeV gg process: M = 2983.1±1.0 MeV/c2, G = 31.3±1.9 MeV CLEOc found the distortion of the hc line shape in y’ decays.

, gg pp

y(1S, 2S)ghcMass width

C.L.<0.0001C.L.=0.0014

53

Sum of 16 of C decay modes

Asymmetric lineshapein decay

Symmetric lineshapein production

The C lineshape is not distorted in the hcC

Background subtracted

c lineshape from 0hc, hcc

54

’c , hc exclusive decays

M: 2984.40.50.6 MeV/c2

width: 30.5 1.0 0.9 MeV : 2.35 0.05 0.04 rad

Relative phase f values from each mode are consistent within 3s, use a common phase value in the simultaneous fit.

BE

SIII

Pre

limin

ary

Possible interference has been take into account

KsKp K+K-p0 p+p-

h

KsK3p 2K2pp0 6p

55

hc (2S)

Observed in different production mechanisms:1. BKhc(2S)

2. gg hc (2S)KKp3. double charmonium production

Belle: PRL 89 102001 (2002)CLEOc: PRL 92 142001 (2004) Belle: NPPS.184 220 (2008); PRL 98 082001(2007)BaBar: PRL 92 142002 (2004); PR D72 031101(2005)BaBar: PR D84 012004 (2011)

M1 transition ’c(2S) CLEO found no signals in 25M y’. BF(y’ghc(2S)) < 7.6×10-4 CLEO: PRD 81 052002 (2010)

Crystal Ball’s “first observation” of ' X never been confirmedPRL 48 70 (1982)

Experimental challenge : search for photons of 50 MeV

56

Observation of c(2S)(KsK)

Width fixed to 12 MeV (world ave.)Events: 50.6±9.7; Significance >6.0 !s

Mass = 3638.5±2.3±1.0 MeV/c2

BESIII preliminary BF(y’ghc(2S)gKsKp)

=(2.98±0.57±0.48)×10-6

BF(hc(2S)KKp)=(1.9±0.4±1.1)%BaBar: PR D78 012006 (2008)

BF(y’ghc(2S))= (4.7±0.9±3.0)×10-4

CLEOc: <7.6×10-4 PR D81 052002 (2010)

Potential model predicts

(0.1~ 6.2)10-4

PRL 89 162002 (2002)

106M

_

57

Summary for c /c(2S)

M(1S) 118 MeV M(2S) 68 MeV

M(1P) = 0 MeV

[1] NPPS 184 220(2008); [2] PRL 92 142001; [3] PoS ICHEP2010:162, 2010

,0)()()(

)/)0((9

)(32)()()(

13

20

11

3

LnMLnMnLM

mm

SnMSnMnSM

hf

qqs

hf

Hyperfine splitting: M(1S) = 112.5 0.8 MeV;

M(2S) = 47.6 1.7 MeV

, L=0

L0

K. Seth hadron11

’

’

’

58

Study X(3872) at BESIII

477 pb-1 data taken @ 4.01GeV (3S)X(3872)

• E~170 MeV, very narrow peak in photon spectrum (energy resolution ~ 4.5 MeV)

(3S) + X/Y/Z(3940)/X(3915)• E=100~125 MeV, narrow peaks in photon spectrum

(width ~ 30 MeV)

Analysis is on going

59

' P(0,,')V P test various mechanisms:Vector meson Dominance Model (VDM); Couplings & form factor; Mixing of -’ (-c);

)')((

))((

nSBF

nSBFnRLO-pQCD predicts R1 R2

PRP 112 173 (1984)

PR D79 111101(2009)

%12~)/(

)'(

XJBF

XBFQ

CLEOc found R2 surprisingly small !R1 = (21.1± 0.9)% R2< 1.8% at 90% CL

Other processes contribute?Or related to the “ rp puzzle”?

60VDM associate with Mixing of c-(’) ? Phys. Lett. B697, 52 (2011)

y’gh’y’gh

+-0

000

’+-

’+-

Mode BF(’) [x10-6] PDG BF(J/) [x10-4] Q (%)

0 1.58 0.42 0.35 0.03 4.5 1.3 1.38 0.49 11.04 0.34 0.13 0.04

’ 126 9 52.8 1.5 2.4 0.2R1 /2 (1.100.39)% (20.9 0.9)% -

BESIII PRL 105, 261801 (2010)Results from BESIIIy’ gp0

γη')BF(V

γη)BF(VR

<<

61

Large cJ V(,,)

• Information of C-even state• Two gluon coupling• Possible glueball or hybrid states• Hadronization

In unit of 10-6

pQCD prediction much lower than experiment

62

Results form BESIII

)(M )(M )(M KK0

An non-pQCD explanation: “hadronic loop correction”arXiv:1005.0066; EPJC70, 177-182 (2010);

BESIII

<10.5228±13±16

<20.8

<12.969.7±7.2±5.6

<6.1

<16.225.8±5.2±2.0

<8.1

First

observation

Phys. Rev. D 83, 112005 (2011)

63

Polarization of c1 V(,,) Longitudinal polarization ( f L ); Transverse polarization ( f

T); q : Helicity angle

015.0014.0034.0158.0

Tf044.0090.0026.0087.0247.0

Tf10.013.009.012.029.0

Tf

1c 1c 1c

22 sin2

1cos)1(

cos TT ffd

d

Z. Phys. C 66, 71 (1995)Phys. Rev. 77, 242 (1950)

22

2

||||

||

LT

TT AA

Af

Longitudinal polarization dominates, consistent with theoretical prediction

64

Reconstruct K+K-

w+-0

cJVV(V:, ) cJ and cJ are Singly

OZI suppressed

cc1ff and cc1ww is suppressed by helicity selection rule.

ccJfw is doubly OZI suppressed, not measured yet

BESIII PRL 107 091803(2011)

65

Evidence

BESIII: PRL 107, 092001 (2011) cJVV at BESIII

Long distance transitions could contribute via the intermediate meson loops.

First observation

ff

ff

ww

wf

PR D81 014017 (2010) PR D81 074006 (2010)

66

Search for c(2S)VV @BESIII

No signals observed in hcrr, K*0K*0, ff;more stringent UL’s are set.

106M y’

Test for the “Intermediate charmed meson loops”

BF(y’ghc’gVV) (10-7)

BF(hc’VV) (10-

3)Theory BF(hc’VV)

(10-3)

r0r0 <11.4 <3.1 6.4 ~28.9

K*0K*0 <19.4 <5.3 7.9 ~ 35.8ff <7.8 <2.0 2.1 ~ 9.8

arXiv: 1010.1343

Observed at BESII in 2003• PRL91, 022001• M=1861+3

-10+5

-25 MeV• Width < 38 MeV (90% CL)• Agree with spin zero

expectation Confirmed at BESIII (& CLEOc)

• M=1861.60.8 (stat.) MeV• Width<8 MeV @ 90% C.L.• M=1859+6

-13+7

-26 MeV• Width < 30 MeV (90% CL)

Many possibilities: • Normal meson?• pp bound state/

multiquark/ glueball/ …

pγpJ/ψ

J/ψππψ' :BESIII -

pγpJ/ψ :BESIII

CPC 34, 421 (2010)

Preliminary

Enhancement at pp threshold

Mpp (GeV)

No significant narrow threshold enhancement is observed here:

(1S ) pp@CLEO

ψ γpp@BESII

J / pp@BESII

PRD 73 (2006) 032001

PRL 99 (2007) 011802

EPJC 53 (2008) 15

BESIII preliminary

ψ γpp@BESIII @CLEOc

69

PWA near pp threshold in J/ppf0(2100) / f2(1910) fixed to PDG. Signif. of X(1835) >>30

70

χcJ

ηc

Obviously different line shape of pp mass spectrum near threshold from that in J/ decays

PWA Projection:Preliminary PWA results:• Signif. of X(pp) is larger than 6.9σ.• The production ratio R:

• It is suppressed compared with “12% rule”.

PWA on the pp mass threshold structure in pp

BESIII

+0.72-3.83= (5.08 0.5

( (

6(

))R

( / (

stat) (syst) 0.12(mod)

)

)%

)

B X pp

B J X pp

-

-

71

X(1835) and two new structures

(Stat. sig. ~ 7.7 ) :

1833.7 6.1( ) 2.7( )

67.7 20.3(stat) 7.7(syst)MeV

BESII result

M stat syst MeV

PRL 95,262001(2005)

BESII

PRL 106, 072002(2011)

f1(1510)

two news! BESIII

• X(1835) was observed in J/’ at BESII.• X(1835) is confirmed at BESIII with 225 M J/. • Two new structures are observed.

BESIII: PRL 106 (2011) 072002

72

Resonance M( MeV/c2) ( MeV/c2) Stat.Sig.

X(1835) 1836.5±3.0+5.6-

2.1

190.1±9.0+38-36 >20σ

X(2120) 2122.4±6.7+4.7-

2.7

83±16+31-11 7.2σ

X(2370) 2376.3±8.7+3.2-

4.3

83±17+44-6 6.4σ

X(1835) consistent with 0-+, but the others are not ruled out.

BESIII fit results (225 M J/y)

PWA needed to understand these structures.

BESIII

Bkg-subtracted;Eff.-corrected

BESIII: PRL 106 (2011) 072002

73

What’s the nature of new structures?

PRD73,014516(2006) Y.Chen et al

0+: 2560(35)(120)2++: 2390(30)(120)

It is the first time the resonant structures are observed in the 2.3 GeV/c2 region, it is interesting since:

LQCD predicts that the lowest lying pseudoscalar glueball: around 2.3 GeV/c2.

J/' decay is a good channel for finding 0-+ glueballs.

Nature of X(2120)/X(2370) pseudoscalar glueball ? / excited states?

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)

t

74

X(1870) in J/X, Xa0(980)

M(a0(980)) M(+)

M(+) M()

a0(980)

f1(1285)

(1405)

arXiv: 1107.1806 (accepted by PRL)X(1870):

7.2

Non a0(980)

non a0/non w

PHSP MC

PHSP MC

New particle？ 2(1870) ？X(1835)?

75

(1405) in J/f0(980)0, f0(980)2

f0(980)-+f1(1285)4.8s

f1(1285)1.4s

preliminarypreliminary

Helicity analysis indicates that peak ~1400MeV is from (1405)f0(980)0 , not from f1(1420):

First observations: (1405)f0(980)0 (isospin violated)

f0(980)00

76

Precision measurement of 3

preliminary preliminary

PDG2010: (3.6+1.1-0.9) 10-3 (2009 CLEO-c)

PDG2010: (1.680.22) 10-3 (1984: GAM2)

h’ ( )gr pp ( )gw ppp

+-0 30

77

Results on N* baryon in pp decay

0.3 7.4 50.3 1.1(5.5 ) 10

061.0027.0014.0027.0130.0

BF('pp)=(6.60.20.6)10-5

BF('N(1535)p)BF(N(1535)p+c.c.) =

PDG2010: (61.2)10-5

N(1535)

M(p) M(pp)

data MC fit A full PWA ana. is performed.

Based on 106M events

N(1535) is 1/2

010.0005.0004.0005.0524.1

Mass (GeV/c2)

Width (GeV)

Preliminary

Mixing intensity provides important information in understanding the nature of a0(980) and f0(980).

Narrow peak (8 MeV) at around 980 MeV can be expected in ηπ (J/ψ f0 a0 ηπ case) or π+π- (c1 a0π0 f0π0 π+π-π0 case) invariant mass spectra.

Study of a0(980) – f0(980) mixing from J/ψ f0 a0 ηπ

c1 a0π0 f0π0 π+π-π0

78

79

PRD 83, 032003 (2011)

80

PRD 83, 032003 (2011)

D0Kp D+Kpp

D0Kppp D0Kpp0

BESIIIPreliminary

BESIIIPreliminary

BESIIIPreliminary

BESIIIPreliminary

BESIII 420 pb-1 (3770), clean single tag sample:

2 2| |BC beam DM E p

Resolution: 1.3 MeV for pure charged modes;1.9 MeV for modes with one .

Summary

Many results are still statistically or systematically

limited.

BEPCII/BESIII has started data taking from

March, 2009. New results obtained.

lum.: 100 times higher ， achieved 2/3

detector: much better performance

Expect new and exciting results from BESIII

Thanks!

北京谱仪实验（ bes ）

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