Upload
acton-barlow
View
155
Download
7
Embed Size (px)
DESCRIPTION
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. 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: - PowerPoint PPT Presentation
Citation preview
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
13
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。
16
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
21
( 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
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
Study of Light hadron spectroscopy
search for non-qqbar 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
Precise measurement of CKM matrix
Search for DDbar mixing, CP violation, etc.
Physics Topics at BES
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
Study of Light hadron spectroscopy
search for non-qqbar 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
Precise measurement of CKM matrix
Search for DDbar mixing, CP violation, etc.
Physics Topics at BES
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
Study of Light hadron spectroscopy
search for non-qqbar 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
Precise measurement of CKM matrix
Search for DDbar mixing, CP violation, etc.
Physics Topics at BES
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!