of 2
1
Search for invisible decays of a dark photon produced in
e
+
e
collisions at
B
A
B
AR
The
B
A
B
AR
Collaboration
The following includes supplementary material for the Electronic Physics Auxiliary Publication Service.
)
2
(GeV
2
X
M
0
5
10
15
20
25
30
)
2
Events / ( 1 GeV
0
1
2
3
4
5
6
7
8
/df = 16.8/35
2
χ
0
5
10
15
20
25
30
Pull
2
0
2
(a)
)
2
(GeV
2
X
M
0
5
10
15
20
25
30
)
2
Events / ( 1 GeV
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
/df = 6.6/35
2
χ
0
5
10
15
20
25
30
Pull
2
0
2
(b)
)
2
(GeV
2
X
M
0
5
10
15
20
25
30
35
)
2
Events / ( 1 GeV
0
2
4
6
8
10
12
14
16
/df = 29.7/38
2
χ
0
5
10
15
20
25
30
35
Pull
2
0
2
(c)
)
2
(GeV
2
X
M
0
5
10
15
20
25
30
35
)
2
Events / ( 1 GeV
0
1
2
3
4
5
6
/df = 14.1/38
2
χ
0
5
10
15
20
25
30
35
Pull
2
0
2
(d)
)
2
(GeV
2
X
M
0
5
10
15
20
25
30
35
)
2
Events / ( 1 GeV
0
1
2
3
4
5
6
/df = 11.5/38
2
χ
0
5
10
15
20
25
30
35
Pull
2
0
2
(e)
)
2
(GeV
2
X
M
0
5
10
15
20
25
30
35
)
2
Events / ( 1 GeV
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
/df = 9.7/38
2
χ
0
5
10
15
20
25
30
35
Pull
2
0
2
(f)
FIG. 1: Distributions of the missing mass squared
M
2
X
in the “lowM” data samples collected near (a,b)
Υ
(2
S
), (c,d)
Υ
(3
S
),
and (e,f)
Υ
(4
S
) resonances. Data are selected with (a,c,e)
R
L
and (b,d,f)
R
T
selections. The solid blue line represents the
background-only fit with
ε
2
0. Normalized fit residuals are shown above each plot.
2
)
2
(GeV
2
X
M
25
30
35
40
45
50
55
60
)
2
Events / ( 0.5 GeV
1
10
1
10
/df = 45.4/78
2
χ
25
30
35
40
45
50
55
60
Pull
2
0
2
(a)
)
2
(GeV
2
X
M
25
30
35
40
45
50
55
60
65
)
2
Events / ( 0.5 GeV
1
10
1
10
/df = 67.3/89
2
χ
25
30
35
40
45
50
55
60
65
Pull
2
0
2
(b)
FIG. 2: Distributions of the missing mass squared
M
2
X
in the “highM” data samples collected near (a)
Υ
(2
S
) and (b)
Υ
(3
S
)
resonances. The solid blue line represents the background-only fit with
ε
2
0. Normalized fit residuals are shown above each
plot.