Search for the 0 "" Glueball in Υ(1S, 2S) decays Sen Jia Beihang University & KEK (on behalf of the Belle&BelleII Collaboration) INTERNATIONAL SCHOOL OF SUBNUCLEAR PHYSICS 56th Course:From gravitational waves to QED, QFD and QCD
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Search for the 0"" Glueball in Υ(1S, 2S) decays
Sen JiaBeihang University & KEK
(on behalf of the Belle&BelleII Collaboration)
INTERNATIONAL SCHOOL OF SUBNUCLEAR PHYSICS56th Course: From gravitational waves to QED, QFD and QCD
OutlinelKEKB and Belle Detector
lBelle2 experiment
lMotivation
lCommon selection criteria
lThe measurements of bottomonium inclusive
decays
lSearch for G0−−
lConslusion
S. Jia, EMFCSC 2018 -2-
KEKB and Belle Detector
KEK, Tsukuba, Japan
8 × 3.5 GeV22 mrad crossing
1999-20101014/fb
The KEKB Collider
World record:
L=2.1×1034/cm2/sec
S. Jia, EMFCSC 2018 -3-
Belle II Experiment
l Nano-beam design (by P. Raimondi for SuperB)
l Double beam currentsl Squeezes beam @IP by 1/20l Target luminosity is 𝓛 =𝟖×𝟏𝟎𝟑𝟓 cm-2s-1 (×40 w.r.t. BELLE)
A hadronic event recorded at 00:38, 26.04.2018the first collision comfirmation
Expected Dataset at Belle2
S. Jia, EMFCSC 2018 -4-
7.0 𝒆" × 4.0 𝒆3 GeV
Motivation
lQCD allows the existences of glueballs.
l There are no definite conclusions from experimental results. One of the reasons is its mixing with quarkonium states.
l The 0-- glueballs are inaccessible by the quarkonium states and their quantum numbers enable their productions in the decays of vector quarkonium easier.
l Search for 0-- glueballs in proposed production channel:Υ(1S,2S) →χ78+ G0
--, Υ(1S,2S) → f1(1285)+ G0--，χ98 → J/ψ+ G0
--,and χ98 →ω+ G0
--. The predicted glueballs masses are 2.80, 3.81 and 4.33GeV/c2.[PRL113, 221601 (2014)]、[JHEP 1510 (2015) 137]
-5-S. Jia, EMFCSC 2018
Data Sample
-6-
2.12E+07 0
1.02E+08
9.32E+06
9.86E+07
1.58E+08
0.00E+00
5.00E+07
1.00E+08
1.50E+08
2.00E+08
1 2 3
Data sample events of Y(1S) and Y(2S) Y(1S) Y(2S)
BABARCLEO BELLE
Belle experiment has collected the largest data samples of Υ(1S,2S) in the world !Analysis Strategy:
In the channels mentioned above, we search for the G0-- signals in the recoil
mass spectra of the χ78, f1(1285), J/ψ, and ω with G0-- widths varying from 0.0
to 0.5 GeV in steps of 0.05 GeV.
S. Jia, EMFCSC 2018
Common selections
S. Jia, EMFCSC 2018 -7-
l |dr| < 0.5cm, |dz| < 4cm and PT<0.1lGood photon candidates, Eγ>50MeV and not match the
extrapolation of any charged tracklNtrack > 4lReconstruct J/ψ, both Re >0.95; one Rµ>0.95 and the other
Rµ>0.05 l For pions, RK<0.4l For J/ψ, η and πA candidates, a mass constraint fit is used.
𝑅C =DE
DE3DFGFHE𝑅I =
DJDJ3DK3DL
𝑅M =DK
DK3DL
Window cuts:J/ψ: |𝑀OPOH-𝑚J/R|<0.03GeV/c2
χ78: 0.36 < 𝐸T∗ < 0.41f1(1285): 1.23<𝑀(𝜂𝜋3𝜋")<1.33GeV/c2
𝜔: 0.755<M(𝜋3𝜋"𝜋A)<0.805GeV/c2
χ78(1P) in Υ(1S, 2S) inclusive decays
l Partition the data samples according to the scaled momentum to correct the efficiency
𝑥 =𝑝[\]∗
12 𝑠� ×(𝑠 − 𝑚[\]
a )
Mode 𝑩𝑹(×10"d) Comments
Υ(1S) ⟶𝜒𝑐1 + 𝑎𝑛𝑦𝑡ℎ𝑖𝑛𝑔 1.90± 0.43± 0.14 with an improved precision
Υ(2S) ⟶𝜒𝑐1 + 𝑎𝑛𝑦𝑡ℎ𝑖𝑛𝑔 2.24± 0.44± 0.20 for the first time
The differential BR
S. Jia, EMFCSC 2018 -8-
lClear f1(1285) signal in ϒ(1S,2S) inclusive decays
l J/ψ production in χ9q (J = 0, 1, 2) decays
Υ 1S, 2S →f1(1285)+X and χ9q → J/ψ+X
Mode 𝑩𝑹(×10"d)
Υ(1S) ⟶ f1(1285)+ anything 46± 28± 13
Υ(2S) ⟶ f1(1285)+ anything 22± 15± 6.3
Mode 𝑩𝑹(×10"y)
𝜒za ⟶ J/ψ + anything 1.5± 0.34± 0.22
𝜒z8 ⟶ J/ψ + anything 1.1 at 90% C.L.
𝜒zA ⟶ J/ψ + anything 2.3 at 90% C.L.
3.5σ
S. Jia, EMFCSC 2018 -9-
The χ78 recoil mass spectra in the (a) Υ(1S) and (b) Υ(2S) data samples.
Measurements of Υ(1S,2S) →χ78/f1(1285) + G0--
The f1(1285) recoil mass spectra in the (a) Υ(1S) and (b) Υ(2S) data samples.
Mode Upper Limits at 90% C.L. Mode Upper Limits at 90% C.L.
Υ(1S,2S) ⟶ χ78 + G 10−5 Υ(1S,2S) ⟶ f1(1285) +G 10-4 -10-
-11-
Measurements of χ98 → J/ψ(ω) + G0−−
Mode Upper Limits at 90% C.L. Mode Upper Limits at 90% C.L.
χ98→J/ψ+G 10−4 χ98→ω+G 10-3
The χ98 is identified through the decay Υ(2S) → γ𝜒z8 .
The γJ/ψ recoil mass spectra in the Υ(2S) data samples.
The γω recoil mass spectra in the Υ(2S) data samples.
S. Jia, EMFCSC 2018
Ø We have searched for the 0−− glueball in ϒ(1S), ϒ(2S), and χ78decays for the first time.
Ø No evident signal is found at three theoretically predicted masses in the processes and 90% C.L. upper limits are set on the branching fractions.
Ø Distinct χ78 and f1(1285) signals are observed in the ϒ(1S) and ϒ(2S) inclusive decays.
Ø The evidence of χ9a → J/ψ+anything
Ø More opportunity in Belle II Experiment.
-12-
Conclusion
More opportunities
PRD 95, 012001 (2017)PRD 96, 112002 (2017)
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