Update on X(3872) J PC determination

Update on X(3872) JPC determination

Soo-Kyung Choi Stephen L. Olsen

Gyeongsang Univ. Univ. of Hawai’i

April Fool’s day 2005 Quarkonium group meeting

In Japan & Korea; not in Hawai’i

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

Use 250 fb-1 ~275M BB prs

Signal(47 ev)Sidebands

(114/10 = 11.4 ev)

Changes since BAM

L=

() is the likelihood ratio:

•Use this value for 2

recommended by PDG (& Golob) for low statistics measurements

•Use MC-generated histograms. Use EvtGen to generate different JPC

scenarios. (Thanks to help from Ishikawa-san.)

PDG Eq32.12

Product Branching Fraction

Use PDG for ’

Areas of investigation

• Search for radiative decays

• Angular correlations in XJ/ decays

• Fits to the M() distribution

Search for X(3872) J/

Select BK J/ (include both K± & Ks)

• Tight J/ cuts• K± id>0.5 / Belle-standard “good Ks” • E>40 MeV• 0 veto (2>4.0)• K* veto (M(K)>1.0 GeV)• R2<0.4; |cosB| < 0.8• |Mbc – 5.28|<0.0055 GeV (2)• |E|<0.034 GeV (2)• E7 E37

Select BK J/BKc1; c1J/

M(J/)

Fit to Mbc & Euse MC to scaleparameters to

the X(3872)

X(3872)?

Look hereM(J/)

13.6 ± 4.4 events@ 3872 MeV

(5.7significance)

Look in X(3872) region

Clear signal in E as well

M( J/) around 3872 MeV

Bkgd level @ 3872 MeV: 2.6 ± 0.6 evts

Prob 3.1evts 13.6 evts <2x10-5

M(J/) “look-back” plot

Br(X J/)

MC:0.19±0.01

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

12.4 ± 4.2 evts

B-meson yields vs M()

Evidence for C=+1is now overwhelming

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

earlier)• M() for XJ/ looks like a

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

Angular Correlations

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

out

example1--: sin2K

K

compute angles inJ/ restframe

D.V. Bugg hep-ph/0410168v2

Use ’ as a check.

’ is 1--

|cos |

2/dof = 16.3/9

|cosKl| for X(3872) events

X(3872) is not 1-- !

backgroundscaled fromsidebands

Signal MC + bkgd

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

expect 2~3evts/bin

1+- and 2--

use J/ helicity angle J/

KX

J/

J/

|cosJ/|

1+-

2--

2/dof = 32/9

2/dof = 20/9

rule out 1+-

0-+ Rosner (PRD 70 094023)

0-+ : sin2 sin2

safe to rule out 0-+

2/dof=18/9

|cos|

|cos|

2/dof=34/9

0 ++

Rosner (PRD 70 094023) again

l

rule out 0++

|cosl|

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

d/dcosl sin2l

2/dof = 41/9

2/dof = 30/9

1++

l

1++: sin2l sin2

K

1++ looks okay!

Rosner (PRD 70 094023)

|cosl|

|cos|

2/dof = 13/9

2/dof = 10/9

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

Fits to the M()

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

J/

q*

q*

Acceptance vs M()

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

S-wave: 2/dof = 43/39

q*roll-off

(CL= 28%)

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

(CL=0.1%)

P-wave: 2/dof = 71/39

q*3

roll-off

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

Summary

• Rule out all possibilities except:– 1++

• Nicely passes all tests

– 2++• Not seriously challenged by this anaysis• BK (2++) should be suppressed• 2++ DD is allowed, should be wide• this is ruled out by Garima et al & Jolanta et al

observation of X DD* Important result!

Needs to be made public

Could the X(3872) be the c1’?

• Mass is off: theory range 39563990 MeV

• (J/)/(J/) = 0.14 ± 0.05 is too small– Naïve expectation for c1’ is ~ 40 or higher

• (c1’J/ violates isospin)

For more details about the results reported here see Belle Note 800 (ver.2 posted today)