T. Barnes ORNL / UTenn SLAC HEP Seminar 23 Feb. 2006
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Transcript of T. Barnes ORNL / UTenn SLAC HEP Seminar 23 Feb. 2006
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T. BarnesORNL / UTennSLAC HEP Seminar23 Feb. 2006
The XYZs of cc:X(3943), Y(3943), Z(3931) and Y(4260)
1. Good old charmonium.
2. The new states:
3S cc? 2P cc? cc hybrids?
How to test these possibilities.
New theor. results mainly abstracted from:T.Barnes, S.Godfrey and E.S.Swanson, hep-ph/0505002, PRD72, 054026 (2005).
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1. Good old charmonium.
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QCD flux tube (LGT, G.Bali et al.;hep-ph/010032)
LGT simulation showing the QCD flux tube
Q Q
R = 1.2 [fm]
“funnel-shaped” VQQ(R)
Coul. (OGE)
linear conft.(str. tens. = 16 T)
Color singlets and QCD exotica “confinement happens”.
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Physically allowed hadron statesPhysically allowed hadron states (color singlets) (color singlets) (naïve, (naïve, valence)valence)
q3 Conventional quark modelmesons and baryons.
q2q2, q4q,…
multiquarks
g2, g3,…
glueballs
maybe 1 e.g.
qqg, q3g,…
hybrids
maybe 1-3 e.g.s
100s of e.g.s
“exotica” :ca. 106 e.g.s of (q3)n, maybe 1-3 others X(3872) = DD*!
(q3)n, (qq)(qq), (qq)(q3),…
nuclei / molecules
(q2q2),(q4q),…
multiquark clusters
dangerouse.g.
_
Basis state mixing may be very important in some sectors.
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qq mesons states
The quark model treats conventional mesons as qq bound states.
Since each quark has spin-1/2, the total spin is
Sqq tot = ½ x ½ = 1 + 0
Combining this with orbital angular momentum Lqq gives states
of total Jqq = Lqq spin singlets Jqq = Lqq+1, Lqq, Lqq-1 spin triplets
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Parity Pqq
= (-1) (L+1)
C-parity Cqq
= (-1) (L+S)
qq mesons quantum numbers
1S: 3S1 1 ; 1S
0 0 2S: 23S
1 1 ; 21S
0 0 …
1P: 3P2 2 ; 3P
1 1 ; 3P
0 0 ; 1P
1 1
2P …
1D: 3D3 3 ; 3D
2 2 ; 3D
1 1 ; 1D
2 2
2D …JPC forbidden to qq are called “JPC-exotic quantum numbers” :
0
; 0 ; 1
; 2 ; 3
…
Plausible JPC-exotic candidates =
hybrids, glueballs (high mass), maybe multiquarks (fall-apart decays).
The resulting qq NL states N2S+1LJ have JPC =
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The (higher) cc spectrum
Pre-dawn, a lava field near Carrizozo, New Mexico.
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Charmonium (cc)A nice example of a QQ spectrum.
Expt. states (blue) are shown with the usual L classification.
Above 3.73 GeV:Open charm strong decays(DD, DD* …):broader statesexcept 1D
2 22
3.73 GeV
Below 3.73 GeV: Annihilation and EM decays.
, KK* , cc, , ll..):narrow states.
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Minimal quark potential model physics:
OGE + linear scalar confinement;
Schrödinger eqn (often relativized) for wfns.
Spin-dep. forces, O(v2/c2), treated perturbatively.
Here…
Contact S*S from OGE;Implies S=0 and S=1 c.o.g. degenerate for L > 0.(Not true for vector confinement.)
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s = 0.5538
b = 0.1422 [GeV2]m
c = 1.4834 [GeV]
= 1.0222 [GeV]
Fitted and predicted cc spectrumCoulomb (OGE) + linear scalar conft. potential
model blue = expt, red = theory.
S*S OGE
L*S OGE – L*S conft, T OGE
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Fitted and predicted cc spectrumCoulomb (OGE) + linear scalar conft. potential
model NR model (LHS) adjacent to GI model (RHS).
S*S OGE
2P
1F
NRGI
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cc from LGT
exotic cc-H at 4.4 GeV
cc has returned.
Small L=2 hfs.
A LGT e.g.: X.Liao and T.Manke, hep-lat/0210030 (quenched – no decay loops).Broadly consistent with the cc potential model. No cc radiative or strong decay predictions from LGT yet.
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Strong decays
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Strong widths of cc resonances
3770
4040
4160
4415
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What are the total widths of cc states above 3.73 GeV?
(These are dominated by open-flavor decays.)
< 2.3 MeV
23.6(2.7) MeV
52(10) MeV
43(15) MeV
78(20) MeV
PDG values
X(3872)
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Experimental R summary (2003 PDG)Very interesting open theoretical question:Do strong decays use the 3P
0 model decay mechanism
or the Cornell model decay mechanism or … ?
br
vector confinement??? controversial
ee, hence 1 cc states only.
How do open-flavor strong decays happen at the QCD (q-g) level?
“Cornell” decay model:
(1980s cc papers)(cc) (cn)(nc) coupling from qq pair production by linear confining interaction.
Absolute norm of is fixed!
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An alternative strong decay modelThe 3P
0 decay model: qq pair production with vacuum quantum numbers.
L I = g
A standard for light hadron decays. It works for D/S in b1 .
The relation to QCD is obscure.
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After restoring this “p3 phase space factor”, the BFs are:
D0D0 : D0D*0 : D*0D*0
One success of strong decay models
An historical SLAC puzzle explained:the weakness of (4040) DD
e.g. DD molecule?
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famous nodal suppression of a 33S
1 (4040) cc DD
std. cc and D meson SHO wfn. length scale
Theor R from the Cornell model.Eichten et al, PRD21, 203 (1980): 4040
DD
DD*
D*D*
4159
4415
partial widths [MeV](3P
0 decay model):
DD = 0.1 DD* = 32.9 D*D* = 33.4 [multiamp. mode]D
sD
s = 7.8
D*D* amplitudes(3P
0 decay model):
1P1 = 0.034
5P1 = 0.151 = 1P
1
5F1
= 0
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2. The new XYYZ states:
3S cc? 2P cc? cc hybrids?
How to test these possibilities.
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Expt. preview, M, and modes, X(3943),X(3943), Y(3943), Y(3943), Z(3931): Z(3931):
J/
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cc spectrum, potential models (dashed: nonrel L, Godfrey-Isgur R) vs data
Possible new cc states at these masses! Z;X,Y;Y
2P or not 2P?
Reminder:Three as yet unknown 1D states.Predicted to have < 1 MeV!
BGS, hep-ph/0505002, PRD72, 054026 (2005).
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cc spectrum, potential models (dashed: nonrel L, Godfrey-Isgur R) vs data
Possible new C=(+) cc states from ee !
2P or not 2P?
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c’
0
c
X(3943)
An interesting new charmoniumproduction mechanism!
Allows access to C=(+) cc states in ee w/o using .
No or !?
X(3943)
[ref] = Belle, hep-ex/0507019, 8 Jul 2005. n.b. Eichten: X(3943) may be the 31S0 cc
c’’.
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Strong Widths: 3P0 Decay Model
33S1
74 [MeV]
31S0
80 [MeV]
3S
DDDD*D*D*D
sD
s
X(3872)
Maybe not 2P?X(3943) = 31S
0
c” ?
(Eichten)
X(3943)
52(10) MeV
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Back to the main theme:
Comparing expt. with theory for 2P cc states.
1st Strong decays (vs. expt.)
2nd EM ( and transitions)
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Trivial observations for 2P cc open-charm strong decays:
Thresholds
DD 3.73 GeVDD* 3.87 GeV
(Ds D
s 3.94 GeV - small)
2’ 2++ 23P
2 DD, DD*
1’ 1++ 23P
1 DD*
0’ 0++ 23P
0 DD
hc’ 1+- 21P
1 DD* but C = (-)
Detailed 2P cc predictions…
J P-allowed D, D* modes (M < D*D*)
Looking for both DD and DD* is a good filter!
n.b. JP = 1+ DD* final states have both S and D amps.
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2P cc Strong Widths: 3P0 Decay Model
DDDD*D
sD
s
2P23P
2 80 [MeV]
23P1
165 [MeV]
23P0
30 [MeV]
21P1
87 [MeV]
(assuming NR ccpotential model masses;BGS, hep-ph/0505002, PRD72, 054026 (2005).)
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Y(3943) B KY(3943), Y J/
[ref] = Belle, PRL94, 182002 (2005).
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Y(3943) = 23P1 cc? (Too light for cc-H.)
Expt for Y(3943): B KY(3943), Y J/ = 87 +/- 22 MeV1++ cc J/ is unusual; cc virtual DD* e.g. -> J/ ?n.b.
IS seen in B decays
Theory for 23P1(3943):
= 135 MeV
A strong DD* mode ?The only open-charm mode?
theoryexpt.
tot
Y(3943)
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Z(3931) Z(3931) DD
[ref] = Belle, hep-ex/0507033, 8 Jul 2005.
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Z(3931) = 23P2 cc ? (suggested by Belle)
Expt for Z(3931): Z(3931) -> DD MeV * BDD
= keV
thy
expt
tot
Theory for 23P2(3931):
= 47 MeV DD*/DD = 0.35 * BDD
= 0.47 keV
( from T.Barnes, IXth Intl. Conf.
on Collisions, La Jolla, 1992.)
The crucial test of Z(3931) = 23P
2 cc :
DD* mode ?
in http://web.utk.edu/~tbarnes/website/Barnes_twophot.pdf
Z(3931)
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Z(3931)
Another possibility for Z(3931)???Another possibility for Z(3931)???
Expt for Z(3931): -> Z(3931) -> DD = 20 +/- 8 +/- 3 MeV * BDD
= 0.23 +/- 0.06 +/- 0.04 keV
Theory for 23P0(3931):
: DD only o.c. mode, theor. tiny! (node) Annih. dominates? Recall
ca. 10 MeV.
ca. 2 keV (not calc.)
* BDD << 2 keV.
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EM transitions
(How one might make 2P cc states.)
What radiative partial widths do we expect from various initial 1 cc states to 2P cc states?
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Strong Widths: 3P0 Decay Model
X(3872)33S
1 74 [MeV]
31S0
80 [MeV]
3S
DDDD*D*D*D
sD
s
52(10) [MeV]
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E1 Radiative Partial Widths
3S -> 2P 33S1 23P
2 14 [keV]
33S1 23P
1 39 [keV]
33S1 23P
0 54 [keV]
31S0 21P
1 105 [keV]
3S -> 1P 33S1 3P
2 0.7 [keV]
33S1 3P
1 0.5 [keV]
33S1 3P
0 0.3 [keV]
31S0 1P
1 9.1 [keV]
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2D 23D3
148 [MeV]
23D2
92 [MeV]
23D1
74 [MeV]
21D2
111 [MeV]
DDDD*D*D*D
sD
s
DsD
s*
78(20) [MeV]
Strong Widths: 3P0 Decay Model
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E1 Radiative Partial Widths
2D -> 1P23D
3 3P
2 29 [keV]
23D2 3P
2 7 [keV]
3P1
26 [keV]
23D1 3P
2 1 [keV]
3P1
14 [keV]
3P0
27 [keV]
21D2 1P
1 40 [keV]
2D -> 1F
23D3 3F
4 66 [keV]
3F3
5
[keV] 3F
2 14
[keV]
23D2 3F
3 44 [keV]
3F2
6 [keV]
23D1 3F
2 51 [keV]
21D2 1F
3 54 [keV]
2D -> 2P23D
3 23P
2 239 [keV]
23D2 23P
2 52 [keV]
23P1
298 [keV]
23D1 23P
2 6 [keV]
23P1
168 [keV]
23P0
483 [keV]
21D2 21P
1 336 [keV]
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Y(4260)
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cc spectrum, potential models (dashed: nonrel L, Godfrey-Isgur R) vs data
Possible 1 state Y(4260).Note no plausible cc assignment exists.A 1 charmonium hybrid??
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Y(4260) ee Y(4260)ISR
, Y J/
log scale
Not seen in R.Hmmm?!
[ref] = BaBar, PRL95, 142001 (2005).
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Y(4260) ? B K Y(4260), Y J/
[ref] = BaBar, hep-ex/0507090 (21 Jul 2005).
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cc-hybrids, theory
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Characteristics of cc-hybrids.
(folklore, mainly abstracted from models, some LGT)
States
(flux-tube model):
The lightest hybrid multiplet should be a roughly degenerate set containing3 exotic and 5 nonexotic JPC;
0, 1, 2, 0, 1, 2, 1, 1
Mass ca. 4.0 – 4.5 GeV, with LGT preferring the higher range.
The 1 should be visible in ee but with a suppressed width. (Hybrid models for different reasons predict
cc(r=0) = 0, suppressing
ee .)
Decays
(flux-tube model and f-t decay model):
Dominant open-charm decay modes are of S+P type, not S+S. (e.g. DD1 not DD or DD*).
n.b. 1(1600) ’ argues against this model.
LGT(UKQCD):
Closed-charm modes like cc-H cc + light mesons are large! (Shown for bb-H; (bb) is preferentially P-wave, and “light mesons” = scalar .)
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p ’p
E.I.Ivanov et al. (E852)PRL86, 3977 (2001).
1(1600)
exotic reported in ’
’is a nice channel because nn couplingsare weak for once (e.g. the a
2(1320) noted here).
The reported exotic P-wave is dominant!
The (only) strong JPC-exotic H candidate signal.
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cc and cc–H from LGT
exotic cc-H at 4.4 GeV
Small L=2 hfs.
A LGT cc-sector spectrum e.g.: X.Liao and T.Manke, hep-lat/0210030 (quenched – no decay loops)Broadly consistent with the cc potential model. No LGT cc radiative or strong decay predictions yet.
n.b. The flux-tube model of hybrids has a lightest multiplet with 8 JPCs;3 exotics and 5 nonexotics, roughly degenerate: (0,1,2) , 1,1Y(4260)?
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PRD52, 5242 (1995).
Early cc-H mass estimates:
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cc-H mass result, 1995 BCS flux tube model calculation ([ref] on prev. slide):
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QQ-H closed-flavor decays from LGT:
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How to test a cc-hybrid assignment, esp. for Y(4260) :
1. Existence
2. Establish the multiplet
3. Decays
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How to test a cc-hybrid assignment, esp. for Y(4260):
1. Existence
Make sure it’s really there. Beware “low-“stuff. Is Y(4260) a real effect?
2. States and Partner States (fill in the multiplet)
Mass ca. 4.0 – 4.5 GeV, with LGT preferring the higher range.
Confirm that no cc states with the same JPC are expected at this mass.
Identify JPC partners of the hybrid candidate nearby in mass. (The most convincing evidence: partners, especially JPC exotics.)
The f-t model expects: 0, 1, 2, 0, 1, 2, 1, 1
The 1 should be visible in ee but with a suppressed width.
3. Decays
Decay modes may be distinctive. BFs and decay amplitudes are very interesting…Some calculations suggest S+P, not S+S, open-charm modes.LGT suggests exotic bb-H
b (
S is large.
The models or LGT assumptions may be wrong (note
1(1600) ’ is S+S).
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Summary, conclusions, suggestions, re expt:
X(3943), Y(3943), Z(3931) and Y(4260) …
1. X(3943) as 31S0
c’’, cc ? DD*-only checks, may be a bit small..
Just measure J P !!! (also Y and Z!)
2. If Y(3943) is the 23P1
1’, one expects a large DD* mode, and no DD.
3. Z(3931) DD vs. DD* can distinguish 0’ from
Belle’s suggested 2’.
…
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Summary, conclusions, suggestions, re expt:
Y(4260) …
4. Y(4260) as hybrid? No new cc 1 expected near this mass: if it exists it’s already something unusual.
Theory folklore says hybrids prefer S+P modes, UKQCD says + light meson(s).
Best approach would be to search for it in all accessible o.c. and c.c. modes. ee DD, DD*, D*D*, DD
0*, DD
1*; J/any other (cc) + light meson mode.
(Close and Page, hep-ph/0507199v2, 30 Sep 2005 gives a detailed list of modes)
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Summary, conclusions, suggestions, re expt (cont.):
X(3943), Y(3943), Z(3931) …
5. (For Beijing I guess…) You can find all three 23P
J cc states using
andDD, DD*.
All three E1 rad BFs of the are ca. 0.5 * 10-3. These could show whether the X,Y,Z (3.9) are 2P cc as speculated.
The End