New Hadron Spectroscopies

Stephen L. Olsen

University of Hawai’i

d cdc c c

ud

usd

History:1930’s: proton & neutron

..all we need???

1950’s: ,,,,,… “Had I foreseen that, I would have

gone into botany” – Fermi

1960’s: The 8-fold way “3 quarks for Mister Mark”

1970’s add charmed particles

1980’s & beauty

1990’s & (finally?) top

chadwick

Fermi

Gell-Mann

Richter Ting

Lederman

Peters Jones

Hadron “zoo”mesons baryons

Quarks restore economy(& rescue future Fermis from Botany?)

(& 3 antiquarks)

Baryons: qqqMesons: q q

p: u+2/3

p: u-2/3

+: d-1/3

u+2/3

d+1/3

u-2/3

u-2/3

d+1//3

u+2/3

-: u+2/3

u-2/3

d+1/3 s+1/3

u+2/3

d-1/3 s-1/3M. Gell-Mann

3 quarks

Fabulously successful, but…

• quarks are not seen

• why only qqq and qq combinations?

• What about spin-statistics?

s-1/3

s-1/3

s-1/3

2 of these s-quarksare in the samequantum state

Das ist verboten!!

The strong interaction “charge” of each quark comes

in 3 different varieties

Y. Nambu O. Greenberg

s-1/3

s-1/3

s-1/3

the 3 s-1/3 quarks in the- have different colorcharges & evade Pauli

-

QCD: Gauge theory for color charges

generalization of QED

+ i e A + i i Gi

QED gauge Xform

QCD gauge Xform

eight 3x3 SU(3) matrices

8 vectorfields

(gluons)

1 vectorfield

(photon)

scalar charge: eisovector charge:

er

eb

eg

QED QCD

NambuGell-Mann & Fritzsch

Attractive configurations

ijk eiejek

i ≠ j ≠ k

ij ei ej

same as the rules for combing colors to get white:

3 different primary colors color-complementary color

eiejek color charges

Hence the name: Quantum Chromodynamics

Difference between QED & QCD

QED: photons have no charge

QCD: gluons carry color chargesgluons interact with each other

Vacuum polarization QED vs QCD

2nf

11CA

in QCD: CA=3, & this dominates

QEDQCD difference

Coupling strength

distance

Testing the Standard Model

QCD X Electro-Weak X QED

decrease in swith distance

Lamb-shiftg-2Atomic spectra…

W, Z & t massesZ width sinW

AsymmetriesCross-sections…

Tests of QED and EW sectorsElectro-Weak sector(tested @ ~0.01% level)QED

(tested @ ppb)

Example:

(g-2)/2|electron

Expt:1,159,652,188.4(4.3)x10-12

Theory:1,159,652,201.4(28)x10-12

Test QCD with 3-jet events(& deep inelastic scattering)

rate for 3-jet events should decrease with Ecm

gluons

“running” s

Why are these people smiling?

Probe QCD from other directions

non-qq or non-qqq hadron spectroscopies:

Pentaquarks:e.g. an S=+1 baryon

(only anti-s quark has S=+1)

Glueballs:gluon-gluon color singlet states

Multi-quark mesons:

qq-gluon hybrid mesons

d cdc

c c

ud

usd

Pentaquarks“Seen” in many experiments

BaBar

CDF

but not seen in just as many others

High interest:1st pentaquark paperhas ~500 citations

Belle

BES

Experimental situation is messy(many contradictory results)

NA49 pp @ Ecm=17 GeV (fixed tgt)(PRL92, 052301: 237+ citations!) COMPASS p @ E =160 GeV (fixed tgt)

1862 ± 2 MeVFWHM = 17 MeV = 5.6

(1862): qqssd

100sof(1530)s but no hint of (1862)hep-ex/0503033

Pentaquark Scoreboard

Positive signals Negative results

Also: Belle Compass L3

Yes: 17 No: 17

Existence of Pentaquarks

is not yet established

multi-quark mesons?

BK J/

M(J)

’J/

X(3872)

Seen in 4 experiments

X(3872)

CDF

X(3872)

D0

hep-ex/0406022

Is the X(3872) a cc meson?

These states are alreadyidentified

3872 MeV

Could it beone of these?

no cc state fits well

3872

c”

hc’

c1’

2

c2

3

M too low and too small

angular dist’n rules out 1

J/ way too small

c too small;M() wrong

c& DD) too small

c should dominate

SLO hep-ex/0407033

back to square 1

DetermineJPC

quantum numbersof the X(3872)

Possible JPC values (for J ≤ 2)

0--

exotic

violates parity

0-+

(c”)

0++

DD allowed

(c0’)

0+-

exotic

DD allowed

1- -

DD allowed

((3S))

1-+

exotic

DD allowed

1++

(c1’)

1+-

(hc’)

2- -

(2)

2- +

(c2)

2++

DD allowed

c2’)

2+-

exotic

DD allowed

Possible JPC values (for J ≤ 2)

0--

exotic

violates parity0-+

(c”)

0++

DD allowed

(c0’)

0+-

exotic

DD allowed

1- -

DD allowed

((3S))

1-+

exotic

DD allowed

1++

(c1’)

1+-

(hc’)

2- -

(2)

2- +

(c2)

2++

DD allowed

c2’)

2+-

exotic

DD allowed

Use 250 fb-1 ~275M BB prs

Signal(47 ev)Sidebands

(114/10 = 11.4 ev)

XJ/’J/

Areas of investigation

• Search for radiative decays

• Angular correlations in XJ/ decays

• Fits to the M() distribution

• Search for X(3872)D*0D0

Search for X(3872) J/

Kinematic variables

CM energy difference:

Beam-constrained mass:

2/

2 )()2( JKCMbc ppEm

BK J

BKJ2// cmJK EEEE

B

Bϒ(4S)

Ecm/2

e e

Ecm/2

Mbc

E

Select BK J/BKc1; c1J/

X(3872)?

13.6 ± 4.4 X(3872)J/evts (>5significance)

M(J/)

Bf(XJ/)

Bf(XJ/)=0.14 ± 0.05

Mbc Mbc

Evidence for X(3872) J/reported last summer hep-ex/0408116)

12.4 ± 4.2 evts

B-meson yields vs M()

Br(B3J/)Br(B2J/)

= 1.0 ± 0.5 Large (near max)Isospin violation!!

Evidence for C=+1is overwhelming

• B J/ only allowed for C=+1• same for B””J/ (reported

earlier)• M() for XJ/ looks like a

Possible JPC values (C=-1 ruled out)

0--

exotic

violates parity0-+

(c”)

0++

DD allowed

(c0’)

0+-

exotic

DD allowed

1- -

DD allowed

((3S))

1-+

exotic

DD allowed

1++

(c1’)

1+-

(hc’)

2- -

(2) 2- +

(c2)

2++

DD allowed

c2’)

2+-

exotic

DD allowed

Angular Correlations

K

J/

J=0J=0X3872

Jz=0

Strategy: for each JPC, find a distrib 0if we see any events there, we can rule it

out

Rosner (PRD 70 094023)

Bugg (PRD 71 016006)

0-+

0-+ : sin2 sin2

safe to rule out 0-+

2/dof=18/9

|cos|

|cos|

2/dof=34/9

0++

l

In the limit whereX(3872), , & J/rest frames coincide:

d/dcosl sin2l

|cosl|rule out 0++

2/dof = 41/9

1++

l

1++: sin2l sin2

K

1++ looks okay!

compute angles inX(3872) restframe

|cosl|

2/dof = 11/9

|cos|

2/dof = 5/9

Possible JPC values (0-+ & 0++ ruled out)

0--

exotic

violates parity

0-+

(c”)

0++

DD allowed

(c0’)

0+-

exotic

DD allowed

1- -

DD allowed

((3S))

1-+

exotic

DD allowed

1++

(c1’)

1+-

(hc’)

2- -

(2) 2- +

(c2)

2++

DD allowed

c2’)

2+-

exotic

DD allowed

Fits to the M()

DistributionXJ/ in P-wave has aq*3 centrifugal barrierX

J/

q*

q*

M() can distinguish -J/ S- & P-waves

S-wave: 2/dof = 43/39 P-wave: 2/dof = 71/39

q*roll-off

q*3

roll-off

(CL=0.1%)(CL= 28%)

Shape of M() distribution nearthe kinematic limit favors S-wave

Possible JPC values (J-+ ruled out)

0--

exotic

violates parity

0-+

(c”)

0++

DD allowed

(c0’)

0+-

exotic

DD allowed

1- -

DD allowed

((3S))

1-+

exotic

DD allowed1++

(c1’)

1+-

(hc’)

2- -

(2)

2- +

(c2)2++

DD allowed

c2’)

2+-

exotic

DD allowed

Search for XD0D00

Select BD0D00 events

|E| |E|22±7 signal evts

Bf(BKX)Bf(XD*D)=2.2±0.7±0.4x10-4Preliminary

D*0D00?

XDD rules out 2++

• 1++ : DD* in an S-wave q*

• 2++ : DD* (or DD) in a D-wave q*5

Strong threshold suppression

Possible JPC values (2++ ruled out)

0--

exotic

violates parity

0-+

(c”)

0++

DD allowed

(c0’)

0+-

exotic

DD allowed

1- -

DD allowed

((3S))

1-+

exotic

DD allowed1++

(c1’)

1+-

(hc’)

2- -

(2)

2- +

(c2)

2++

DD allowed

c2’)

2+-

exotic

DD allowed

1++1++

a 1++ cc state?• 1++ c1’

– Mass is off

– c1’ J/ violates Isospin, should be suppressed.

3872

(XJ/)/(XJ/)

Theory: ~ 30Expt: 0.14 ± 0.05

c1’ component of the X(3872) is ≤ few %

Intriguing fact

MX3872 =3872 ± 0.6 ± 0.5 MeV

mD0 + m D0* = 3871.2 ± 1.0 MeV

lowest masscharmed meson

lowest mass spin=1charmed meson

X(3872) is very near DD* threshold.is it somehow related to that?

hh bound states (hadronium)?

p n D D*

deuteron:

loosely bound 3-q

color singlets with Md = mp+mn-

Hadronium (dueson):

loosely bound q-q color

singlets with M = mD + mD* -

attractive nuclear force attractive force??

There is lots of literature about this possibility

N. Tornqvisthep-ph/0308277

X(3872) = D0D*0 bound state?

• JPC = 1++ is favored

• M≈mD0 + mD0*

• Maximal Isospin violation is natural: |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/) is expected

Equal mixture of I=1 & I =0

Swanson PLB 598, 197 (2004)

Tornqvist PLB 590, 209 (2004)Swanson PLB 588, 189 (2004)

X(3872) conclusion

•Not a cc state

•Most likely a D0D*0 bound state

C C

d cdc

1st well establishedtetraquark

Are there others?

Look at other B decays hadrons+J/

BK J/

BK J/

BK J/

BK …

BK J/ in Belle

“Y(3940)”M≈3940 ± 11 MeV≈ 92 ± 24 MeV

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/

Y(3940): What is it? (continued)

• another tetraquark?– M ≈ 2mDs

– not seen in YJ/• ( contains ss)

– width too large??– need to search for Y(3949)DSDS

s csc

??PRL 93, 041801

M( J/)

Y(3940): What is it? (continued)

• cc-gluon hybrid?– predicted by lattice QCD,– decays to DD and DD* are suppressed– large hadron+J/ widths are predicted– masses expected to be 4.3 ~ 4.4 GeV

(higher than what we see)

c c

Summary• X(3872):

– JPC established as 1++

– cc component is small (≤ few %)– all measured properties are consistent with

a D0D*0 bound state 1st established tetraquark!

• Y(3940):– No obvious cc assignment– tetraquark seems unlikely– cc-gluon hybrid?

– Lots to do:• determine JPC • search for other decay channels (DD*, DsDs, …)

d cdc

c c

Other hadronium states?

M=1859 MeV/c2

< 30 MeV/c2 (90% CL)

J/pp in the BES expt

M(pp)-2mp (GeV)

0 0.1 0.2 0.3

acceptance

2/dof=56/56

fitted peak location

+3 +510 25

J.Z.Bai PRL 91,022001(2003)

The case of the mystery

meson

Stephen L. Olsen

University of Hawai’i

SU(3) S>0

S<0

baryonsoctets & decuplets

Meson octets

Hence the name: Quantum Chromo Dynamics

q

q

q

q

q

q

confinement

Grand Unification?

s

QED

EW

“Data, I need data.I can’t make bricks without clay”

10 34

1fb -1/day

Strategy: for each JPC, find a distrib 0if we see any events there, we can rule it

out

Ex: 1--: sin2K

K

compute angles inJ/ restframe

D.V. Bugg hep-ph/0410168v2

’2/dof = 8.9/9

Use ’ to check accept.’ is 1--

|cosKl| for X(3872) events

X(3872) is not 1-- !

expect 2~3evts/bin

backgroundscaled fromsidebands

fit withsin2Kl + bkgd

2/dof = 45/9 see 8 evts/bin

1+- and 2--

use J/ helicity angle J/

KX

J/

J/

|cosJ/|

For the ’J/,this should be ~flat

1+- and 2--

can rule out 1+- (Cl < 0.1%)

|cosJ/|

1+-: sin2J/2--: sin2J/ cos2J/

2/dof=32/9 2/dof=20/9

|cosJ/|

Narrow multi-quark mesons?

• DsJ(2317) & DsJ(2457)

• X(3872)J/

CLEO

M(Ds)M(Ds

*)

M(J)

What are the DsJ states?

Belle found

B D DsJ(2317) D DsJ(2457)

and

DsJ(2457)Ds

Angular analysis for B D DsJ

DsJDs()

J=1

J=0

DsJ(2317) Ds0

J=1

J=2

DsJ(2460) Ds

zJz=0

DsJ(2317) = 0+

DsJ(2547) = 1+

J=0

DsJ fit into cs spectrum(with a mass shift)

DsJ(2547) = 1+

DsJ(2317) = 0+

DsJ states are likelyordinary L=1 cs

mesons

Theory got the masses wrong