60
3 Phenomenology of the Massive Dark Photon
[MeV]
χ
m
1
1 0
2
10
3
10
4
)
A'
/m
χ
(m
D
α
2
ε
y=
15
−
10
14
−
10
13
−
10
12
−
10
11
−
10
10
−
10
9
−
10
8
−
10
7
−
10
-
, e
0
π
SBND,
CO HE RE NT
-1
Belle II - 20 fb
CRESST-II
SuperCDMS
B D
X
r e li c d e n s it y
Elastic Scalar Dark Matter
L D M
X
@
C E R N , 1 6 G e V
L D M
X
@
C E R N , 8 G
e V
SHiP
= 0.1
D
α
= 3
χ
/m
A'
m
++
N A 6 4 (e )
Fig. 3.10 Future sensitivities for proposed experiments for massive dark photon for m A > 1 MeV
in the plane of the yield variable y as a function of dark matter mass m χ for an elastic scalar dark
matter particle. Projections for SHiP [97], BDX [98], SBND [99], LDMX@CERN [57, 59], SENSEI
with a proposed 100 g detector operating at SNOLAB [100], and SuperCDMS at SNOLAB [101].
The plot is revised from [36]
pseudo-Dirac fermions and scalars, which have velocity suppressed annihilation
cross sections, are usually studied.
The current bounds and future perspectives in the plane y versus dark matter
mass are shown in Figs. 3.9 and 3.10 under the hypothesis that the dark matter is
a scalar particle and for a specific choice of α d (α d = 0.1) and the ratio between
the mediator and the dark matter masses (m A /m χ = 3). In these plots, the lower
limit for the thermal relic density is also shown, under that hypothesis that a single
dark-matter candidate is responsible for the whole dark-matter abundance. It is worth
noting that results from accelerator-based experiments are largely independent of the
assumptions on a specific dark matter nature as dark matter at accelerators is produced
in relativistic regime and the strength of the interactions with light mediators and
SM particles is only fixed by thermal freeze-out.
Current bounds come from the same experiments using missing energy/missing
momentum techniques contributing to the {ε, m A } sensitivity plot (BaBar and
NA64(e)) with the addition of the re-interpretation of data from old neutrino experiments (E137 [13] and LSND [94]) and results from current neutrino experiments
(MiniBooNE [95]) exploiting dark matter scattering on nucleons and/or electrons.
Bounds can also be derived by using a superfluid He-4 detector, as shown in [103],
but they lie at the margin of the range included in Fig. 3.9.
In all the bounds shown for electron beam-dump or missing energy experiments,
we are neglecting the contribution of secondary positrons in dark photon production
through annihilation on atomic electrons, as for example studied in [14].
3 Phenomenology of the Massive Dark Photon
[MeV]
χ
m
1
1 0
2
10
3
10
4
)
A'
/m
χ
(m
D
α
2
ε
y=
15
−
10
14
−
10
13
−
10
12
−
10
11
−
10
10
−
10
9
−
10
8
−
10
7
−
10
-
, e
0
π
SBND,
CO HE RE NT
-1
Belle II - 20 fb
CRESST-II
SuperCDMS
B D
X
r e li c d e n s it y
Elastic Scalar Dark Matter
L D M
X
@
C E R N , 1 6 G e V
L D M
X
@
C E R N , 8 G
e V
SHiP
= 0.1
D
α
= 3
χ
/m
A'
m
++
N A 6 4 (e )
Fig. 3.10 Future sensitivities for proposed experiments for massive dark photon for m A > 1 MeV
in the plane of the yield variable y as a function of dark matter mass m χ for an elastic scalar dark
matter particle. Projections for SHiP [97], BDX [98], SBND [99], LDMX@CERN [57, 59], SENSEI
with a proposed 100 g detector operating at SNOLAB [100], and SuperCDMS at SNOLAB [101].
The plot is revised from [36]
pseudo-Dirac fermions and scalars, which have velocity suppressed annihilation
cross sections, are usually studied.
The current bounds and future perspectives in the plane y versus dark matter
mass are shown in Figs. 3.9 and 3.10 under the hypothesis that the dark matter is
a scalar particle and for a specific choice of α d (α d = 0.1) and the ratio between
the mediator and the dark matter masses (m A /m χ = 3). In these plots, the lower
limit for the thermal relic density is also shown, under that hypothesis that a single
dark-matter candidate is responsible for the whole dark-matter abundance. It is worth
noting that results from accelerator-based experiments are largely independent of the
assumptions on a specific dark matter nature as dark matter at accelerators is produced
in relativistic regime and the strength of the interactions with light mediators and
SM particles is only fixed by thermal freeze-out.
Current bounds come from the same experiments using missing energy/missing
momentum techniques contributing to the {ε, m A } sensitivity plot (BaBar and
NA64(e)) with the addition of the re-interpretation of data from old neutrino experiments (E137 [13] and LSND [94]) and results from current neutrino experiments
(MiniBooNE [95]) exploiting dark matter scattering on nucleons and/or electrons.
Bounds can also be derived by using a superfluid He-4 detector, as shown in [103],
but they lie at the margin of the range included in Fig. 3.9.
In all the bounds shown for electron beam-dump or missing energy experiments,
we are neglecting the contribution of secondary positrons in dark photon production
through annihilation on atomic electrons, as for example studied in [14].