Exotic meson search at J-PARC

Tsutomu Mibe
Department of Physics,Ohio University
Workshop on Hadron Structure at J-PARC
November 30- December 2, 2005 @ KEK, Japanq q-bar mesons

Idea of quark comes fromlowest lying scalar andvector mesons (Gell-mann).
Existence of analogous
symmetry in excited states
is a great success of Quark
model.

Is there any meson which
doesn’t fit this scheme…?
J-PARC workshop, 2005 Dec. 02
Exotic meson search at JJ-PARC, T. Mibe

Non q q-bar mesons
Glueballs– which have no valence quarksHybrid mesons– which contain a valence quarkantiquark pair and one or more gluons.

Tetra-quark states– which have two valence quarkantiquark pairs.

qThese states are identified
experimentally as a state with exotic
quantum number and/or anomalous
properties beyond q q-bar description.

J-PARC workshop, 2005 Dec. 02
Exotic meson search at JJ-PARC, T. Mibeq qq qq

Tetra-quark meson candidatesa0(980) and f0(980)– Non-exotic quantum number– Large branching to K K-bar– Production in φ radiative decay favors a compact 4q stateπ(1400)– Exotic spin-parity JPC=1-+– Found in ηπ decay.
– ηπ coupling is suppressed for qqg hybrid, possibly 4q state.

f1(1420), f1(1510)– Three 1++ states around M~1.5 GeV/c2 ,f1(1285), f1(1420),f1(1510)– Two are expected to be members of P-wave q q-bar nonet,
another state is possibly 4q state.

J-PARC workshop, 2005 Dec. 02
Exotic meson search at JJ-PARC, T. Mibe

Tetra-quark meson
candidates cont’dDSJ (2317) and DSJ (2460)– Data consistent with non-exotic quantum number– Mass is below the quark model prediction.
– Tetra-quark?, T. Browder et al, PLB578, 365 (2005)

X(3872)– Doesn’t fit quark model prediction– Tetra-quark?, Maiani et al, PRD 71, 014028 (2005)– or D0D0* bound state?

 There is no definitive evidence of flaver-exotic tetraquark states.

J-PARC workshop, 2005 Dec. 02
Exotic meson search at JJ-PARC, T. Mibe

Flavor exotic tetra quark states


R. Jaffe, Phys. Rev. D15, 267 (1977)– spires citation 1000+!
– Example, JP=1+ qqqq states in 18 group.

Flavor exoticstatedsuu
J-PARC workshop, 2005 Dec. 02
Exotic meson search at JJ-PARC, T. Mibe

udssusdd

S=+2 meson search
Phys. Lett. 17 155 (1965)
Γ=110+/-40 MeV

J-PARC workshop, 2005 Dec. 02
Exotic meson search at JJ-PARC, T. Mibe

K+p scattering at CERN withp(K+)=3-5 GeV/c.
Structure beyond phase spacearound M(KK,S=+2)=1280 MeV
Selection of forward going KK
pair enhances the structure.
Consistent with peripheralproduction.

Phys. Rev. 177 1991 (1969)

S=+2 meson ?
Following K+p experimentsdidn’t confirm the peak at1280 MeV in M(KK,S=+2)
system.

J-PARC workshop, 2005 Dec. 02
Exotic meson search at JJ-PARC, T. Mibe

Phys. Lett. 27B 665 (1968)

M(KK) (GeV)Is S=+2 meson ruled out?
No signal for X++ÆKK, KKπ– Iso-vector states have not been found.
– if it exists, cross sections should be too small or width is too wide
to see a peak in old low statistics data (~a few 10 events/bin).

Remaining possibility is I=0 sector.
– renewed interests in Θ+ era– Tetra-quark state as a cousin of Θ+ (several theoreticalsuggestions, next slide)
Phys. Lett. 17 155 (1965)– only one published data with– very limited statistics.

J-PARC workshop, 2005 Dec. 02
Exotic meson search at JJ-PARC, T. Mibe

M(K+K0) (GeV/c2)

Possible I=0, S=+2 states as acousin of Θ+JP

Dominant decay mode

Reference

0-

KKπ0+

KKππ

Karliner and Lipkin, Phys.
Lett. B612, 197 (2005)

1-KK (P wave)

Burns, Close and Dudek,
Phys. Rev. D71,014017(2005)

1+KKπ or KK*

Kanada-En’yo, Morimatsuand Nishikawa, Phys. Rev.
D72, 014505 (2005)
Cui et al.,hep-ph/0511150
all model predicts width of state < 100 MeV

J-PARC workshop, 2005 Dec. 02
Exotic meson search at JJ-PARC, T. Mibe

JP=1+ S=+2 tetra-quark meson anda non-strange partner
Kanada-En’yo, Morimatsu and Nishikawa, Phys. Rev. D72, 014505 (2005)

Three f1 mesons (JPC=1++) in M~1.5 GeV/c2
Two f1 mesons are expected to appear in this mass region as P-wave
q q-bar nonet.
The other may be non q q-bar meson, e.x. 4q state.
Flux-tube quark model supports this idea.

J-PARC workshop, 2005 Dec. 02
Exotic meson search at JJ-PARC, T. Mibe

High statistics K+p experiment at JPARC
J-PARC– Intense secondary Kaon beamfrom 50 GeV protons



K+X(S=+2)

KKSearch for Iso-scalar S=+2
meson in K+p reaction

π– Initial state strangeness =+1– Only requires ∆S=+1 to make
S=+2 final stateFinal states
Σ+ K+K0–– Σ+ K+K+π– Σ+ K+K0π+π

Analogous search for S=-2
meson is possible in K-p reaction

J-PARC workshop, 2005 Dec. 02
Exotic meson search at JJ-PARC, T. MibepHyperon(S=-1)

f1(1420) and f1(1510) in K-pscattering
4.2 GeV/c K- beam @CERNK-p Æ K-(+) K0s π+(-) ΛPWA favors JPC=1++
Peripheral production
σ(K-pÆf1Λ)BR(f1ÆKK0π)– f1(1420): 4.8 +/- 1.5 ub– f1(1510): 18 +/- 2 ub
– (in forward hemisphere)f1(1510) was also observedin K-p scattering at SLACLASS (D. Aston et al.,
PLB201 573(1988))
J-PARC workshop, 2005 Dec. 02
Exotic meson search at JJ-PARC, T. Mibe

4.2 GeV/c K- beam @CERN
Gavillet et al., Z.Phys.C16,119(1982)
f1(1510)
f1(1420)?

Production mechanism of tetraquark meson in KN scattering
usu
s

K- us

K+ us

f1

K+/K+*

puu
dX+

suu

Σ+

K0/K0*
sudσ(K-p Æf1(uuss)0Λ)~5-20 µb
J-PARC workshop, 2005 Dec. 02
Exotic meson search at JJ-PARC, T. Mibeusds

Λp~=?

duuσ(K+p ÆX(udss)+Σ+)Requirements
5 GeV/c K+ beam for S=2 meson search up to M~2 GeV/c2 inK+pÆY X reaction.
If cross section for f1 is taken as a guide, sensitivity ~1 µb– 105 K+/sec, 50 cm LH2, 1 µb cross section– 0.2 event/sec, 22k events/day

Large acceptance at forward angles for peripheral mesonproductions.
Capability of multi-particle detection for charged particles(detection of neutrals is optional).
Good examples in past meson factories with charged particle
spectromenter– LASS @SLAC– E852 @BNL AGS

J-PARC workshop, 2005 Dec. 02
Exotic meson search at JJ-PARC, T. MibeHistorical major players in meson
spectroscopy
LASS @ SLAC

J-PARC workshop, 2005 Dec. 02
Exotic meson search at JJ-PARC, T. Mibe

E852 @ BNL AGS

Summary

Renewed interest for flavor exotic S=+2 tetra-quark mesons.
Existence of such states can be tested in a high statistics
experiment in K+p reaction.

J-PARC is an ideal place for such an experiment.

Key requirements for the experiment are– High intensity K+ beam.
– Large acceptance spectrometer at forward angles– Capability of multi-particle detection

J-PARC workshop, 2005 Dec. 02
Exotic meson search at JJ-PARC, T. Mibe