Is There A ++ State?&

RHIC – Exotic Factory !

Huan Z. Huang Department of Physics and Astronomy University of California, Los Angeles

Thanks: Jingguo Ma, An Tai, Haibin Zhang and Sevil Salur

Outline

• Pentaquark + nK+ or pKS

• Is There a ++ ?

• What may be the implication on production mechanism?

• RHIC – an exotic particle factory!

Spring-8 Result

1.540.01 GeV< 25 MeVGaussian significance 4.6

+

+ C(n/p) K- K+ (n/ p)

Cuts: no K+K-

no recoil p (n only)Missing mass for n

PRL 91, 012002 (2003)

MeVMeV7.8

CLAS/JLAB Results

Phys.Rev.Lett.91, (2003) 252001

MeVMeV5.2

d→p n p→n +

Phys. Rev. Lett. 92, (2004) 032001

Where Reaction Mass Width ’s*LEPS C K+K- X 1540 +-

10< 25 4.6

DIANA K+Xe K0p X 1539 +- 2

< 9 4.4

CLAS d K+K-p(n) 1542 +- 5

< 21 5.2

SAPHIR p K+K0(n) 1540 +- 6

< 25 4.8

ITEP A K0p X 1533 +- 5

< 20 6.7

CLAS p +K-K+

(n)1555 +- 10

< 26 7.8

HERMES e+d K0p X 1528 +- 3

13 +- 9

~5

ZEUS e+p e’K0p X

1522 +- 3

8 +- 4 ~5

COSY pp K0p+ 1530 +- 5

< 18 4-6

Many Experiments Confirm +

*Gaussian statistical significance: estimated background fluctuation

Many Experiments with Null Results

Noticeably (biased list)

CDF p + p Very High Energy

HERA-B p + A sqrt(s) 42 GeV Inclusive SPHINX p + C sqrt(s) 11.5 GeV Exclusive K

hep-ex/0407026

BESBaBar e+ + e- collisionsALEPHDELPHI

ZEUS Result

ICHEP04 Result bump ~1480 MeV/c2

+K0p

= (4.2+-0.9+1.2-0.9)%

No ++pK+ was observed!

???

+ Exotic Baryon

M1890-180*Y] MeV

D. Diakonov, V. Petrov, and M. Polyakov, Z. Phys. A 359 (1997) 305.

• Exotic: S=+1

• Low mass: 1530 MeV

• Narrow width: ~ 15 MeV

• Jp=1/2+

Isospin = 0

Is There a ++ State (I=1, Instead 0)?

The SAPHIR Collaboration at ELSA

Is There a State (I=1, Instead 0)?

CLAS Results

No signal in pK-(K+p) channel

The production of is not favored in photon reactionsif the assumed mechanism for production is correct !

The STAR Detector

MagnetMagnet

CoilsCoils

Central Central TriggerTriggerBarrel Barrel (CTB)(CTB)

ZCalZCal

Time Time Projection Projection

ChamberChamber(TPC)(TPC)

Year 2000Year 2000

Barrel EM Cal Barrel EM Cal (BEMC)(BEMC)

Silicon Vertex Silicon Vertex Tracker (SVT)Tracker (SVT)Silicon Strip Silicon Strip Detector (SSD)Detector (SSD)

FTPCFTPCEndcap EM CalEndcap EM CalFPDFPD

TOFp, TOFrTOFp, TOFr

Year 2001+Year 2001+

DAQ: currently running at ~100x design rate for TPC

Particle identificationParticle Identification: dE/dx from TPC

Future TOF Upgrade significantly enhances STAR PID

STAR Pentaquark Searches

-- - + - (NA49 pentaquark state)

N + KS

+ p + KS

++ p + K+

Data Set:Au + Au 200 GeV run 2 (~1.7 M, 30-80%) p + p data 200 GeV run 2 (~8 M, Z<75cm)d + Au 200 GeV run 3 (18.4 M)Au + Au 63 GeV run 4 (5.1 M)

STAR can make an important contribution in this area !!

A Stringent Limit from HERA-B

HERA-B hep-ex/0408048sqrt(s) 42 GeVpA (C,Ti,W) 200 M inelastic events+/ <0.92%; 95%CL+/(1520) <2.7%; 95% CL

Does this imply (1520)/ ~ 34%?

The ++/ ratio should be small !

Some Theory publications since 2003

D. Diakonov et al. (chiral quark soliton) Naive quark model S. Capstick et al. (isotensor formulation) Fl. Stancu, D.O. Riska (qq with int.) A. Hosaka (chiral potential) M. Karliner et al.(qq-qqq) R. L. Jaffe et al. (qq-qq-q : 10 + 8) J. Sugiyama et al. (QCD sum rule) F. Csikor et al. (Lattice QCD) S. Sasaki (Lattice QCD)

: 1/2+, I=0: 1/2

: 1/2, 3/2, 5/2, I=2: 1/2+

: 1/2+ (strong ): 1/2+, I=0 : 1/2+, I=0: 1/2, I=0: 1/2+ -> 1/2: 1/2

Mass, width, Spin, Parity, Production mechanism, Partners…

(

implies I=1 and possibly invalids all these models !

Ohashi/Spring-8

Possible + Hadro-Production Reactions

Coalescence or Secondary Production of e+e- is not favored (deuteron is a good measure of sensitivity) very high energy (CDF) is not favored very violent collisions (central Au+Au, e.g.) not favoredK+n and K+p experiments should be done again

at appropriate energy !

Possible + Photo-Production Reactions

CLAS/JLABLEPS/SPring-8

Exclusive Channels !

Explains no ++ in pK-K+p

Pentaquark or Molecule?

If state has isospin I = 1, there will be0 n + KS

Critical confirmation for I = 1 !!

The structure of the NK or K molecule state cannot be ruled out !

A critical test of experimental sensitivity is the production of deuterons how many (anti-)deuterons have been seen in CDF and e+e collisions?

RHIC – Exotic Particle Factory

RHIC – Dense Partonic Matter andRapid Hadronization

Unique Production Mechanism for Possible Exotic Particles

Exotic Mesons, Pentaquarks, Di-baryons [ and Strangelets

Empirical Quark Scaling in RAA and v2

STAR

PHENIX

Baryon

Meson

Constituent (n) Quark Scaling-- Meson n=2 and Baryon n=3 grouping

Saturation of v2 at Intermediate pT

Hadronization of Bulk Partonic Matter

PR

L 92

(20

04

) 05

23

02

; PR

L 91

(20

03

) 18

23

01

At hadron formation time there is a collective v2

among constituent quarks

Recombination/coalescence provides a hadronization scheme (not necessarily related to partonic matter, works for d+Au)

Possible geometrical nature of v2 saturation – surface emission

Clustering and Surface Emission

Volcanic mediate pT – Spatter (clumps)

Enhancement of Clustersat intermediate pT !

Search for Multi-quark (>3) Cluster State at RHIC !

STAR – Exciting Physics Program A full TOF and Heavy Flavor Tracker upgrade will greatly enhance STAR’s capability !!

RHIC – Exotic Particle Factory

Heavy Flavor TrackerUsing Active Pixel Sensor

two layers of thin silicon detector 1.5 cm and 4 cm radius Charmed Exotics?!Full Barrel TOF Using MRPC

Exotic Particles Hadrons with internal structure beyond existing

QCD qqq and q-qbar framework !!

pp pA

AA

pppA

AA

Exotic

RHIC – Dedicated QCD Machine & Beyond

(spin) (CGC,EMC)

(Deconfinement Phase Transition)

The End

Embedding

Theta++ Invariant Mass

Opening AngleProton Momentum

Kaon Momentum

++ : Flat in rapidity –0.8<y<0.7 Flat in pt 0.4<pt<1.2

ZEUS Result

No ++pK+ was observed!

Why +, not ++ ?

Charge ordering in jet fragmentation?

???

Au + Au Collisions at RHIC

STARSTAR

Central Event

(real-time Level 3)