Spectroscopy issues at a Super B factory. Antimo Palano INFN and - - PowerPoint PPT Presentation

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Spectroscopy issues at a Super B factory.

Antimo Palano INFN and University of Bari Super-B factory Workshop, Hawaii, April 20, 2005. ✷ In the last few years charm and charmonium spectroscopy has received a new revival due to the discovery of new unexpected particles. ✷ New results on Spectroscopy from B-factories are coming from:

• B decays;
• Charm decays;
• Inclusive e+e− interactions;
• γγ collisions;
• Initial State Radiation;

✷ Important issue for spectroscopy: Exclusive or Semi-exclusive reactions.

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Some Issues in Spectroscopy.

✷ Among the still unsolved questions heavy and light meson spectroscopy I will focus on:

• Completing the charm and charmonium spectrum;
• Solving the question of the existence of gluonium or hybrid states.

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The charm spectrum.

✷ The recent discoveries in the charm spectrum put back into question the validity of the potential models. ✷ Therefore it is important to establish the complete spectrum of charm. The ¯ cu/d spectrum. ✷ Where are the charm radial excitations?

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The charm spectrum.

✷ The ¯ cs spectrum after the discovery of the DsJ states. ✷ Are there still unexpected particles to be found?

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The new DsJ states.

✷ The new DsJ states have been interpreted as:

• The missing c¯

s states. For reasons still to understand potential models predict wrong masses.

• 4-quark states or molecules. In this cases other states should be found.

Some of them could be narrow.

• The discovery of a new phenomenon

such as Chiral Doubling? In this case again new states are expected to be found.

• M. A. Nowak et al., hep-ph/0307102

W.A. Bardeen et al., hep-ph/0305049

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Charm spectrum: information from continuum.

✷ Narrow states can be extracted from continuum e+e− annihilations using hard p∗ cuts. This is being done at current B-factories. ✷ The BaBar discovery of the new DsJ states:

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Charm spectrum: information from continuum.

✷ The process of isolating charm decays from continuum is quasi-exclusive: a large part of the non − c and combinatorial background is removed by applying a high p∗ cut. ✷ However, spin-parity analysis is impossible in continuum production except for a few cases. ✷ Broad states cannot be isolated from continuum. ✷ Presence of reflections from other narrow states.

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Charm spectrum: information from B decays.

✷ Broad states can only be extracted from B decays. BELLE evidence for D∗

0(2308) → D+π− in B− → D+π−π−.

20 40 60 80 100 120 140 2 2.5 3 3.5

D*

2

D* Dv

*,Bv *

MDπ min(GeV/c2) Events/20 MeV/c2

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Charmonium spectrum.

✷ It is important to establish the complete spectrum of charmonium.

4 5 6 7 8 9 10 11 12 JPC 0-+ 1-- 1+- 0++ 1++ 2++ 2-+ 2-- 3-- 3+- 3++exotic 1.5 2 2.5 3 3.5 4 4.5 5

2S+1LJ 1S0 3S1 1P1 3P0 3P1 3P2 1D2 3D2 3D3 1F3 3F3 n.a.

m r0 m/GeV 1-+ ηc J/Ψ hc χc0 χc1 χc2 0+- 2+- 0+- glueballs experiment DD** DD CP-PACS Columbia hybrids

✷ Several states still missing. Are there hybrid charmonium states?

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Charmonium hybrids.

✷ S. Godfrey: the existence of gluonium excitations in the hadron spectrum is

• ne of the most important unanswered questions in hadron physics.

✷ Hybrid mesons ψg consists of ¯ ccg. ✷ The flux tube model predicts 8 states between 4 and 4.2 GeV. ✷ Lattice QCD calculations predict the JP C = 1−+ state between 4.04 and 4.4

• GeV. The proximity of D∗D thresholds could make it narrow.

✷ Some hybrids can have exotic quantum numbers such as: ψg(JP C = 0+−, 2+−) → J/ψ + (π+π−), η, η′ ψg(JP C = 1−+) → ηc + (π+π−), η, η′ ✷ Some of these states could be produced in B decays. ✷ Hybrid mesons with JP C = 1−− could be looked for in e+e− annihilations via ISR.

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Charmonium spectrum.

✷ New charmonium states can be extracted from B decays: ✷ The J/ψπ+π− mass spectrum from B decays in BELLE from B+ → K+J/ψπ+π−:

0.40 0.60 0.80 1.00 1.20

M(π+π-J/ψ) - M(J/ψ) (GeV/c2)

200 400

Events/0.010 GeV/c2 11

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Charmonium spectrum.

✷ But also JP C = evenx+ can be obtained from γγ collisions. ✷ The Observation of ηc and ηc(2S) from BaBar from γγ.

BABAR

✷ γγ collisions are also an ηc factory.

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Charmonium spectrum.

✷ The Observation of χc0 and χc2 from BELLE in γγ collisions.

W [GeV]

2.4 2.6 2.8 3 3.2 3.4 3.6 3.8 4

Nevent / 20MeV

50 100 150 200 250 300

• π

+

π

• K

+

K

c0

χ

c2

χ

✷ γγ collisions are also a χc0,2 factory.

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Charmonium from ISR.

✷ The JP C = 1−− charmonium states can be observed from ISR e+e− → γJ/ψ. ✷ The J/ψ → π+π−π0 from BaBar.

M3π (GeV/c2) events/(2.5 MeV/c2)

25 50 75 100 2.9 3 3.1 3.2 3.3

✷ BaBar, for events having the ISR γ reconstructed : 10 events per fb−1. With 20ab−1: 200 K events. Similar to the actual BES statistics. A super B-factory is also a charmonium factory.

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Status of gluonium searches.

✷ Lattice QCD predicts the scalar gluonium around 1.7 GeV:

++ −+ +− −−

PC

2 4 6 8 10 12

r0mG

2

++ ++

3

++ −+

2

−+ *−+

1

+−

3

+−

2

+− +−

1

−−

2

−−

3

−−

2

*−+ *++

1 2 3 4 mG (GeV) 15

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Status of gluonium searches.

✷ Too many scalar mesons below 2. GeV. I = 1/2 I = 1 I = 0 k(800) σ a0(980) f0(980) f0(1370) K∗

0(1430)

a0(1490) f0(1500) f0(1700) K∗

0(1950)

✷ Two nonets? 4-quark states? Gluonium? ✷ Where is the scalar glueball? ✷ Many proposals. Narrow: f0(1500), f0(1700). Wide: σ. ✷ Information on some of these states, such as the existence of k(800) and σ can be extracted from existing data from charm decays. ✷ Unlikely to produce gluonium in charm decays.

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Search for gluonium in B decays.

✷ The possibility of searching for gluonium in B decays has been suggested by the experimental measurement of a large decay rate for: B → η′X, B → η′K ✷ The diagram giving rise to these processes is: b → sg ✷ There are arguments in favour of a gluonic content of the η′, therefore gluonium states may be produced in B decays.

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✬ ✫ ✩ ✪ ✷ The total rate b → sg has been calculated perturbatively: B(b → sg) = (2 − 5) × 10−3 ✷ One should look for: B → K(∗)ππ, KK, ηη, ηη′ in searching for scalar or tensor states. ✷ One should look for: B → K(∗)ηππ, K ¯ Kπ in searching for pseudoscalar states.

• H. Fritzsch, Phys. Lett. B415 (1997) 83
• P. Minkowski and W. Ochs hep-ph/0404194

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Search for gluonium in B decays.

✷ Present data. Study of: B → K + scalar(tensor) ✷ BELLE: π+π− mass spectrum in B+ → K+π+π−

20 40 60 80 100 120 140 160 180 1 2 3 4 5

M(π+π-) (GeV/c2) Events/(0.05 GeV/c2) (b)

5 10 15 20 25 30 2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0

✷ Strong f0(980) signal. ✷ Wide scalar structure around 1.3 GeV. f0(1300)? ✷ No f0(1500).

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Search for gluonium in B decays.

✷ BELLE: K+K− mass spectrum in B+ → K+K+K−

20 40 60 80 100 120 0.5 1 1.5 2 2.5 3 3.5 4

M(K+K-)min (GeV/c2) Events/(0.05 GeV/c2) (d)

10 20 30 40 50 60 0.99 1.00 1.01 1.02 1.03 1.04 1.05

✷ f0(1500) or f ′

2(1525)?

✷ Actually very limited statistics in the search for the pseudoscalar gluonium in: B → K(ηππ), (ηππ)

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Gluonium in double charmonium sample?

✷ Observation by BELLE of an unexpected large rate for: e+e− → J/ψηc and e+e− → J/ψ(¯ cc)

Recoil Mass(J/ψ) GeV/c2 N/20 MeV/c2

25 50 75 100 2 2.5 3 3.5 4 4.5

25 50 75 3.5 3.6 3.7 3.8 3.9 4 4.1 4.2

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Gluonium in double charmonium sample?

This discovery has triggered triggered some authors to suggest that this rate may be partly due to the presence of a gluonium state: e+e− → ¯ ccgg

γ* G

J

H

• S. Brodsky et al., hep-ph/0305269

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Conclusions

✷ A Super B-factory is also a τ/charm factory but also a charmonium factory. ✷ Charm, charmonium, light and exotic meson spectroscopy can receive new inputs and possibly new unexpected states could be found.

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