Post on 13-Jan-2016
Non-standard mesons in BES III?
Stephen L. Olsen, Univ of Hawai’iBES annual mtg Shi-dou, May 30-June 2, 2005
non-standard hadronsnon-qqq baryons or non-qq mesons:
Pentaquarks:e.g. an S=+1 baryon
Glueballs:gluon-gluon color singlet states
Multi-quark mesons:
qq-gluon hybrid mesons
u cuc
c c
ud
usd
mesons with “hidden charm” are a good place to look
• standard cc mesons are:– best understood theoretically– decay properties well known– narrow & non overlapping
• concentrate on charmonium-like particles that don’t match expected properties
c cu c
uc
What about the (4.03) ?
Conventional wisdom: (4.03)= S)
Ecm(GeV/c)
DD DD
*
D*D
*
D momentum spectra @ 4.03GeV
D+ D0
Ling-jun Pan, BES data
D*D*
DD*
DDD*D*
DD*
DD
Why is ((4.03) D*D*) so huge?
DD/DD*/D*D*: 1/20/64 phase-spaceCharmonium S-wave: 1/4/7 removed D-wave: 1/1/4
Suggestions
D* D*u
c
u
c
(4.03)=D*D*molecule?
c c
a cc-gluonhybrid?
PRL 38, 317
PLB 366, 323
hadronic molecules
a new spectroscopy?
DeRujula, Georgi,Glashow, PRL 38, 317 (1977)
Many possibilitiesFor BESIII
cc-gluon hybrids
another new spectroscopy?
Hybrid states
More possibilitiesFor BESIII
1–- hybridmixes with(4.03)??
“ normal”cc mesons
cc gluonhybrids
DD
Belle has candidates for each
• DD* molecular state: X(3872)– S.-K. Choi et al PRL 91, 262001
• cc-gluon hybrid: Y(3940)– S.-K/ Choi et al, PRL 94, 182882
The X(3872)
M(J) –M(J/)
’
X(3872)
M() MeV
XJ/XJ/XJ/
M(J/)
seen in:
& XD0D
M(D0D0) MeV
Ispin isviolated
C=+
X(3872) = D0D*0 bound state?
• JPC = 1++ (favored by DD* models)
• M ≈ mD0 + mD0*
• Maximal isospin violation is natural (& was predicted): |I=1; Iz= 0> =1/2(|D+D*->+ |D0D*0>) |I=0; Iz= 0> =1/2(|D+D*-> - |D0D*0>)
|D0D*0> = 1/2(|10> - |00>)
• (XJ/) < (XJ/)
Equal mixture of I=1 & I =0
Swanson PLB 598, 197 (2004)
Tornqvist PLB 590, 209 (2004)
Swanson PLB 588, 189 (2004)
X(3872) conclusionsee hep-ex/0505037 & 0505038
•JPC = 1++
•cc content is small
•matches all(?) expectations for a D0D*0 bound state
C C
D* D*u
c
u
c
BES has a candidate too!from Ling-Jun’s (4.03) DX study
Study this
Look at DD* region
D*+D+0 D*+D+0
D*+D+
D*+D++
D*0D00
D*0D0
Fits to momentum spectra are poor
Too few daughters
D0
D+
D* Br’s fixed at PDG values2/dof = 129/78
CL:0.028%
L.J. Pan, PhD thesis
Addsome (4.03)Ũ; ŨDD
2/dof = 100/73CL: 5%
Br?=16%
MŨ~3860 MeVŨ<12 MeV
L.J. Pan, PhD thesis
ŨDD
ŨDD
DeRujula, Georgi,Glashow, PRL 38, 317 (1977)
X(3872)??Ũ(3860)
ŨDD allowe
d
BK J/
“Y(3940)”M≈3940 ± 11 MeV≈ 92 ± 24 MeV
Mbc Mbc Mbc
S.K. Choi et al, PRL 94, 182882Bf(BKY)Bf(YJ/)=7.1±1.3±3.1x10-5
cc gluon candidate from Belle: Y(3940)
Y(3940): What is it?
• Charmonium?– Conventional wisdom: J/ should not be
a discovery mode for a cc state with mass above DD & DD* threshold!
• Some kind of -J/ threshold interaction?– the J/is not surrounded by brown
muck; can it act like an ordinary hadron?
J/
Brambilla et al (QWG) hep-ph/0412158Eichten, Lane & Quigg PRD 64, 094019Barnes, Godfrey & Swanson hep-ph/0505002
Y(3940): What is it (cont’d)?
• another 4-quark state?– M ≈ 2mDs
– not seen in YJ/• ( contains ss)
– width too large??– no exchange for DSDS
s csc
??
PRL 93, 041801
M( J/)
Y(3940): What is it (cont’d) ?
• cc-gluon hybrid?– predicted by QCD,– decays to DD and DD* are suppressed (“open-charm” thresh = mD + m D** = 4.3 GeV)
– large hadron+J/ widths are predicted– masses expected to be 4.3 ~ 4.4 GeV
(higher than what we see)
c c
Horn & Mandula PRD 17 898 (1978)
Close PLB 342, 369 McNiele et al PRD 65
094505
Isgur et al PRL 54, 869 (1995)
“ open charm” threshold for hybrids is here
Ecm(GeV/c)
DD
DD
* D*D
*
Hybrid states in this mass range may decay to x
J/orcc,…)x=light hadrons
Search strategies for BESIII
• DD(*) molecular states– (4.03)() + Ũ
•Study DD & DD* masses @ (4.03) (& (4.16)??)
• light cc gluon hybrids– (4.03) + ccg hybrid
•Study J/ (c, c) + light hadons () @ (4030), (4160) (& (4415)??)
Rate estimates (DD(*) molecules)(1yr = 6fb-1)
• L.-J. Pan’s thesis:~16% of (4.03)DD
yield is via:(4.03) Ũ(3860) DD
If DD recon effic ~0.1% Expect: 103
Ũ(3860)DD/yr
including
D Br’s
Rate estimates (cc-gluon hybrids)
• (4.03) + (cc gluon hybrid)– assume:((4.03)J/)~((3.77)J/
)~100keVRecon effic J/y ~ 1%
Can search in many other channels:(4.03)() + J/ ( J/, c, …)
N((4.03)J/) ~ 103/yr x((4.03) J/)
((3.77)J/)
or, or
Summary
BESIII runs at 4.03 (& 4.16 GeV + higher?)
may be very interesting.
謝謝
Announcement
謝謝
Backup slides
Look at events where 2 D mesons are found
????
L.J. Pan, PhD thesis
Expect ~ 10 ??(3860)DD events