update on x(3872) j pc determination
DESCRIPTION
Update on X(3872) J PC determination. Soo-Kyung Choi Stephen L. Olsen Gyeongsang Univ. Univ. of Hawai’i. In Japan & Korea; not in Hawai’i. April Fool’s day 2005 Quarkonium group meeting. Possible J PC values (for J ≤ 2). Use 250 fb -1 ~275M BB prs. Signal - PowerPoint PPT PresentationTRANSCRIPT
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)