${{\mathit A}^{0}}$ (Axion) Production in Hadron Collisions

INSPIRE   PDGID:
S029AXP
Limits are for ${\mathit \sigma (}{{\mathit A}^{0}}{)}$ $/$ ${\mathit \sigma (}{{\mathit \pi}^{0}}{)}$.
VALUE CL% DOCUMENT ID TECN  COMMENT
• • We do not use the following data for averages, fits, limits, etc. • •
1
ACCIARRI
2023
ARNT ${{\mathit A}^{0}}$ $\rightarrow$ ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$
2
BERTUZZO
2023
ARNT ${{\mathit A}^{0}}$ $\rightarrow$ ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$
3
AAD
2022J
ATLS ${{\mathit H}}$ $\rightarrow$ ${{\mathit A}^{0}}{{\mathit A}^{0}}$ , ${{\mathit Z}}{{\mathit A}^{0}}$ ( ${{\mathit A}^{0}}$ $\rightarrow$ ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$)
4
TUMASYAN
2022AH
CMS ${{\mathit H}}$ $\rightarrow$ ${{\mathit A}^{0}}{{\mathit A}^{0}}$, ${{\mathit A}^{0}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$ , ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$
5
TUMASYAN
2022R
CMS ${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit A}^{*0}}$ $\rightarrow$ ${{\mathit Z}}{{\mathit Z}}$ , ${{\mathit Z}}{{\mathit H}}$
6
AAD
2021F
ATLS Monojet + missing $p_T$
7
AAD
2021K
ATLS Mono-${{\mathit \gamma}}$ + missing $p_T$
8
AAD
2021N
ATLS ${{\mathit \gamma}}{{\mathit \gamma}}$ scatt. in ${}^{}\mathrm {Pb}+{}^{}\mathrm {Pb}$
9
CARRA
2021
ATLS ${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit A}^{*0}}$ $\rightarrow$ ${{\mathit W}}{{\mathit W}}$ , ${{\mathit Z}}{{\mathit \gamma}}$
10
AAIJ
2020AL
LHCB ${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit X}^{0}}$ $\rightarrow$ ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$
11
GAVELA
2020
CMS ${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit A}^{*0}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \gamma}}$ , ${{\mathit Z}}{{\mathit Z}}$
12
SIRUNYAN
2019BQ
CMS ${{\mathit X}^{0}}$ $\rightarrow$ ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$
13
JAIN
2007
CNTR ${{\mathit A}^{0}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$
14
AHMAD
1997
SPEC ${{\mathit e}^{+}}$ production
15
LEINBERGER
1997
SPEC ${{\mathit A}^{0}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$
16
GANZ
1996
SPEC ${{\mathit A}^{0}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$
17
KAMEL
1996
EMUL ${}^{32}\mathrm {S}$ emulsion, ${{\mathit A}^{0}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$
18
BLUEMLEIN
1992
BDMP ${{\mathit A}^{0}}$ ${{\mathit N}_{{{Z}}}}$ $\rightarrow$ ${{\mathit \ell}^{+}}{{\mathit \ell}^{-}}{{\mathit N}_{{{Z}}}}$
19
MEIJERDREES
1992
SPEC ${{\mathit \pi}^{-}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit n}}{{\mathit A}^{0}}$, ${{\mathit A}^{0}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$
20
BLUEMLEIN
1991
BDMP ${{\mathit A}^{0}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$, 2${{\mathit \gamma}}$
21
FAISSNER
1989
OSPK Beam dump, ${{\mathit A}^{0}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$
22
DEBOER
1988
RVUE ${{\mathit A}^{0}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$
23
EL-NADI
1988
EMUL ${{\mathit A}^{0}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$
24
FAISSNER
1988
OSPK Beam dump, ${{\mathit A}^{0}}$ $\rightarrow$ 2 ${{\mathit \gamma}}$
25
BADIER
1986
BDMP ${{\mathit A}^{0}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$
$<2. \times 10^{-11}$ 90 26
BERGSMA
1985
CHRM CERN beam dump
$<1. \times 10^{-13}$ 90 26
BERGSMA
1985
CHRM CERN beam dump
27
FAISSNER
1983
OSPK Beam dump, ${{\mathit A}^{0}}$ $\rightarrow$ 2 ${{\mathit \gamma}}$
28
FAISSNER
1983B
RVUE LAMPF beam dump
29
FRANK
1983B
RVUE LAMPF beam dump
30
HOFFMAN
1983
CNTR ${{\mathit \pi}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit n}}{{\mathit A}^{0}}$ ( ${{\mathit A}^{0}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$)
31
FETSCHER
1982
RVUE See FAISSNER 1981B
32
FAISSNER
1981
OSPK CERN PS ${{\mathit \nu}}$ wideband
33
FAISSNER
1981B
OSPK Beam dump, ${{\mathit A}^{0}}$ $\rightarrow$ 2 ${{\mathit \gamma}}$
34
KIM
1981
OSPK 26 GeV ${{\mathit p}}$ ${{\mathit N}}$ $\rightarrow$ ${{\mathit A}^{0}}$ X
35
FAISSNER
1980
OSPK Beam dump, ${{\mathit A}^{0}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$
$<1. \times 10^{-8}$ 90 36
JACQUES
1980
HLBC 28 GeV protons
$<1. \times 10^{-14}$ 90 36
JACQUES
1980
HLBC Beam dump
37
SOUKAS
1980
CALO 28 GeV ${{\mathit p}}$ beam dump
38
BECHIS
1979
CNTR
$<1. \times 10^{-8}$ 90 39
COTEUS
1979
OSPK Beam dump
$<1. \times 10^{-3}$ 95 40
DISHAW
1979
CALO 400 GeV ${{\mathit p}}{{\mathit p}}$
$<1. \times 10^{-8}$ 90
ALIBRAN
1978
HYBR Beam dump
$<6. \times 10^{-9}$ 95
ASRATYAN
1978B
CALO Beam dump
$<1.5 \times 10^{-8}$ 90 41
BELLOTTI
1978
HLBC Beam dump
$<5.4 \times 10^{-14}$ 90 41
BELLOTTI
1978
HLBC ${\mathit m}_{{{\mathit A}^{0}}}=1.5$ MeV
$<4.1 \times 10^{-9}$ 90 41
BELLOTTI
1978
HLBC ${\mathit m}_{{{\mathit A}^{0}}}$=1 MeV
$<1. \times 10^{-8}$ 90 42
BOSETTI
1978B
HYBR Beam dump
43
DONNELLY
1978
$<0.5 \times 10^{-8}$ 90
HANSL
1978D
WIRE Beam dump
44
MICELMACHER
1978
45
VYSOTSKII
1978
1  ACCIARRI 2023 search for axions in the NuMI neutrino beam target, which are produced through mixings with mesons due to the coupling with gluons, and exclude $\mathit f_{{{\mathit A}^{0}}}$ around tens of TeV for ${\mathit m}_{{{\mathit A}^{0}}}$ = $0.2 - 0.9$ GeV. They assume a slightly suppressed axion coupling to muons. See their Fig. 4 for the limits.
2  BERTUZZO 2023 employs an analysis analogous to ACCIARRI 2023. They search for leptophilic axions primarily produced via ${{\mathit \tau}}$ $\rightarrow$ ${{\mathit \mu}}{{\mathit A}^{0}}$ and ${{\mathit \tau}}$ $\rightarrow$ ${{\mathit e}}{{\mathit A}^{0}}$, and exclude $\mathit f_{{{\mathit A}^{0}}}$ around $1 \times 10^{6} - 6 \times 10^{7}$ GeV for ${\mathit m}_{{{\mathit A}^{0}}}$ = $0.2 - 1.7$ GeV. See their Fig. 2 for the limits.
3  AAD 2022J set upper limits for the cross sections of ${{\mathit H}}$ $\rightarrow$ ${{\mathit A}^{0}}{{\mathit A}^{0}}$ $\rightarrow$ 4 ${{\mathit \mu}}$ and ${{\mathit H}}$ $\rightarrow$ ${{\mathit Z}}{{\mathit A}^{0}}$ $\rightarrow$ 2 ${{\mathit \ell}}$2 ${{\mathit \mu}}$. See their Figs. 14 and 17 for the respective mass-dependent limits.
4  TUMASYAN 2022AH set the limits of $\mathit O(10^{-6}$) with respect to the product of the branching fractions of ${{\mathit H}}$ $\rightarrow$ ${{\mathit A}^{0}}{{\mathit A}^{0}}$ and ${{\mathit A}^{0}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$ , ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$. They also derive limits on the effective axion couplings contributing to ${{\mathit H}}$ $\rightarrow$ ${{\mathit A}^{0}}{{\mathit A}^{0}}$ and ${{\mathit H}}$ $\rightarrow$ ${{\mathit Z}}{{\mathit A}^{0}}$. See their Figs. 5 and 7 for the limits.
5  TUMASYAN 2022R is analogous to GAVELA 2020, and set a limit on the products of the axion couplings to gluons and ${{\mathit Z}}$ bosons as $\mathit G_{{{\mathit A}} {{\mathit Z}} {{\mathit Z}}}$ $\mathit G_{{{\mathit A}} {{\mathit g}} {{\mathit g}}}$ $<$ $6.64 \times 10^{-7}$ GeV${}^{-2}$ at 95$\%$ CL for $\mathit f_{{{\mathit A}^{0}}}$ = 3 TeV and ${\mathit m}_{{{\mathit A}^{0}}}$ $<$ 100 GeV. Here we use $\mathit c_{{{\widetilde{\mathit G}}}}$ = $\mathit G_{{{\mathit A}} {{\mathit g}} {{\mathit g}}}$ $\mathit f_{{{\mathit A}^{0}}}$/4 and $\mathit c_{{{\widetilde{\mathit Z}}}}$ = $\mathit G_{{{\mathit A}} {{\mathit Z}} {{\mathit Z}}}$ $\mathit f_{{{\mathit A}^{0}}}$/4 to translate their limits. They also set a limit on the product of the axion couplings to gluons and ${{\mathit Z}}{{\mathit H}}$. See their Fig. 9 for the $\mathit f_{{{\mathit A}^{0}}}$-dependent limits.
6  AAD 2021F look for axion production with an energetic jet and large missing $p_T$, and set a limit on the axion coupling to gluons, $\mathit c_{{{\widetilde{\mathit G}}}}/\mathit f_{{{\mathit A}^{0}}}$ $<$ $8 \times 10^{-6}$ GeV${}^{-1}$ at 95 $\%$ CL for ${\mathit m}_{{{\mathit A}^{0}}}$ = 1 MeV. Using $\mathit c_{{{\widetilde{\mathit G}}}}$ = $\alpha _{s}/8\pi $, we interpret the limit as $\mathit f_{{{\mathit A}^{0}}}$ $>$ $0.4$ TeV for $\alpha _{s}$ $\simeq{}$ 0.08.
7  AAD 2021K look for axion production with an energetic photon and large missing $p_T$, and set a limit on the axion coupling to a ${{\mathit Z}}$ boson and photon, $\mathit G_{{{\mathit A}} {{\mathit Z}} {{\mathit \gamma}}}$ $<$ $5.1 \times 10^{-4}$ GeV${}^{-1}$ at 95 $\%$ CL for ${\mathit m}_{{{\mathit A}^{0}}}$ = 1 MeV and assuming $\mathit G_{{{\mathit A}} {{\mathit \gamma}} {{\mathit \gamma}}}$ = 0.
8  AAD 2021N look for axion production using the measurement of light-by-light scattering based on ${}^{}\mathrm {Pb}+{}^{}\mathrm {Pb}$ collision data. They set the limit on the axion-photon coupling, $\mathit G_{{{\mathit A}} {{\mathit \gamma}} {{\mathit \gamma}}}$ $<$ $5.3 \times 10^{-5} - 3.4 \times 10^{-4}$ GeV${}^{-1}$ at 95 $\%$ CL for ${\mathit m}_{{{\mathit A}^{0}}}$ = $6 - 100$ GeV. Here we use $\Lambda _{a}$ =$\mathit G_{{{\mathit A}} {{\mathit \gamma}} {{\mathit \gamma}}}{}^{-1}$ to translate their limits. See their Fig. 9 for mass-dependent limits.
9  CARRA 2021 is analogous to GAVELA 2020, and they use the differential cross sections for ${{\mathit W}}{{\mathit W}}$ and ${{\mathit Z}}{{\mathit \gamma}}$ production measured with the ATLAS detector to set limits on the product of the axion couplings to gauge bosons as $\mathit G_{{{\mathit A}} {{\mathit W}} {{\mathit W}}}$ $\mathit G_{{{\mathit A}} {{\mathit g}} {{\mathit g}}}$ $<$ $6.2 \times 10^{-7}$ GeV${}^{-2}$ and $\mathit G_{{{\mathit A}} {{\mathit Z}} {{\mathit \gamma}}}$ $\mathit G_{{{\mathit A}} {{\mathit g}} {{\mathit g}}}$ $<$ $3.7 \times 10^{-7}$ GeV${}^{-2}$ at 95 $\%$ CL for ${\mathit m}_{{{\mathit A}^{0}}}{ {}\lesssim{} }$ 100 GeV.
10  AAIJ 2020AL look for a light new boson decaying into a pair of muons using the LHCb data with an integrated luminosity of 5.1 fb${}^{-1}$, and set limits on the cross section over a range of ${\mathit m}_{{{\mathit X}^{0}}}$ = $0.22 - 3$ and $20 - 60$ GeV. See Figs. 8 and 9 for mass-dependent limits.
11  GAVELA 2020 focus on the axion production as an s-channel off shell mediator, and use the Run 2 CMS public data to set limits on the product of the axion couplings to gluons and photons as well as ${{\mathit Z}}$ bosons as $\mathit G_{{{\mathit A}} {{\mathit \gamma}} {{\mathit \gamma}}}$ $\mathit G_{{{\mathit A}} {{\mathit g}} {{\mathit g}}}$ $<$ $2.8 \times 10^{-7}$ GeV${}^{-2}$ and $\mathit G_{{{\mathit A}} {{\mathit Z}} {{\mathit Z}}}$ $\mathit G_{{{\mathit A}} {{\mathit g}} {{\mathit g}}}$ $<$ $9.8 \times 10^{-7}$ GeV${}^{-2}$ for ${\mathit m}_{{{\mathit A}^{0}}}{ {}\lesssim{} }$ 200 GeV. See their Fig.3 for the limits.
12  SIRUNYAN 2019BQ look for the pair production of a new light boson decaying into a pair of muons, and set limits on the product of the production cross section times branching fraction to dimuons squared times acceptance over a range of ${\mathit m}_{{{\mathit X}^{0}}}$ = $0.25 - 8.5$ GeV. See the right panel of their Fig. 1 for mass-dependent limits.
13  JAIN 2007 claims evidence for ${{\mathit A}^{0}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$ produced in ${}^{207}\mathrm {Pb}$ collision on nuclear emulsion (${}^{}\mathrm {Ag}/{}^{}\mathrm {Br}$) for $\mathit m({{\mathit A}^{0}}$) = $7$ $\pm1$ or $19$ $\pm1$ MeV and $\tau ({{\mathit A}^{0}}$) ${}\leq{}$ $10^{-13}$ s.
14  AHMAD 1997 reports a result of APEX Collaboration which studied positron production in ${}^{238}\mathrm {U}+{}^{232}\mathrm {Ta}$ and ${}^{238}\mathrm {U}+{}^{181}\mathrm {Ta}$ collisions, without requiring a coincident electron. No narrow lines were found for $250<\mathit E_{{{\mathit e}^{+}}}<750$ keV.
15  LEINBERGER 1997 (ORANGE Collaboration) at GSI looked for a narrow sum-energy ${{\mathit e}^{+}}{{\mathit e}^{-}}$-line at $\sim{}635~$keV in ${}^{238}\mathrm {U}+{}^{181}\mathrm {Ta}$ collision. Limits on the production probability for a narrow sum-energy ${{\mathit e}^{+}}{{\mathit e}^{-}}$ line are set. See their Table$~$2.
16  GANZ 1996 (EPos$~$II Collaboration) has placed upper bounds on the production cross section of ${{\mathit e}^{+}}{{\mathit e}^{-}}$ pairs from ${}^{238}\mathrm {U}+{}^{181}\mathrm {Ta}$ and ${}^{238}\mathrm {U}+{}^{232}\mathrm {Th}$ collisions at GSI. See Table$~$2 for limits both for back-to-back and isotropic configurations of ${{\mathit e}^{+}}{{\mathit e}^{-}}$ pairs. These limits rule out the existence of peaks in the ${{\mathit e}^{+}}{{\mathit e}^{-}}$ sum-energy distribution, reported by an earlier version of this experiment.
17  KAMEL 1996 looked for ${{\mathit e}^{+}}{{\mathit e}^{-}}$ pairs from the collision of ${}^{32}\mathrm {S}$ (200$~$GeV/nucleon) and emulsion. No evidence of mass peaks is found in the region of sensitivity ${\mathit m}_{\mathrm {{{\mathit e}} {{\mathit e}}}}>$2 MeV.
18  BLUEMLEIN 1992 is a proton beam dump experiment at Serpukhov with a secondary target to induce Bethe-Heitler production of ${{\mathit e}^{+}}{{\mathit e}^{-}}$ or ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$ from the produce ${{\mathit A}^{0}}$. See Fig.$~$5 for the excluded region in ${\mathit m}_{{{\mathit A}^{0}}}-\mathit x$ plane. For the standard axion, $0.3<\mathit x<$25 is excluded at 95$\%$ CL. If combined with BLUEMLEIN 1991, $0.008<\mathit x<$32 is excluded.
19  MEIJERDREES 1992 give $\Gamma\mathrm {( {{\mathit \pi}^{-}} {{\mathit p}} \rightarrow {{\mathit n}} {{\mathit A}^{0}})}\cdot{}$B( ${{\mathit A}^{0}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}})/\Gamma\mathrm {( {{\mathit \pi}^{-}} {{\mathit p}} \rightarrow all)}$ $<10^{-5}$ (90$\%$ CL) for ${\mathit m}_{{{\mathit A}^{0}}}$ = 100 MeV, ${\mathit \tau}_{{{\mathit A}^{0}}}$ = $10^{-11} - 10^{-23}~$sec. Limits ranging from $2.5 \times 10^{-3}$ to $10^{-7}$ are given for ${\mathit m}_{{{\mathit A}^{0}}}$ = $25 - 136$ MeV.
20  BLUEMLEIN 1991 is a proton beam dump experiment at Serpukhov. No candidate event for ${{\mathit A}^{0}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$, 2${{\mathit \gamma}}$ are found. Fig.$~$6 gives the excluded region in ${\mathit m}_{{{\mathit A}^{0}}}-\mathit x$ plane ($\mathit x~$= tan $\beta $ = $\mathit v_{2}/\mathit v_{1}$). Standard axion is excluded for $0.2$ $<$ ${\mathit m}_{{{\mathit A}^{0}}}$ $<$ $3.2$ MeV for most $\mathit x~>~$1, $0.2 - 11$ MeV for most $\mathit x~<~$1.
21  FAISSNER 1989 searched for ${{\mathit A}^{0}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$ in a proton beam dump experiment at SIN. No excess of events was observed over the background. A standard axion with mass 2${\mathit m}_{{{\mathit e}}}-$20 MeV is excluded. Lower limit on $\mathit f_{{{\mathit A}^{0}}}$ of $\simeq{}10^{4}$ GeV is given for ${\mathit m}_{{{\mathit A}^{0}}}$ = 2${\mathit m}_{{{\mathit e}}}-$20 MeV.
22  DEBOER 1988 reanalyze EL-NADI 1988 data and claim evidence for three distinct states with mass $\sim{}1.1$, $\sim{}2.1$, and $\sim{}9$ MeV, lifetimes $10^{-16}-10^{-15}~$s decaying to ${{\mathit e}^{+}}{{\mathit e}^{-}}$ and note the similarity of the data with those of a cosmic-ray experiment by Bristol group (B.M.$~$Anand, Proc. of the Royal Society of London, Section A A22 183 (1953)). For a criticism see PERKINS 1989, who suggests that the events are compatible with ${{\mathit \pi}^{0}}$ Dalitz decay. DEBOER 1989B is a reply which contests the criticism.
23  EL-NADI 1988 claim the existence of a neutral particle decaying into ${{\mathit e}^{+}}{{\mathit e}^{-}}$ with mass $1.60$ $\pm0.59$ MeV, lifetime ($0.15$ $\pm0.01$) $ \times 10^{-14}~$s, which is produced in heavy ion interactions with emulsion nuclei at $\sim{}$4 GeV/$\mathit c$/nucleon.
24  FAISSNER 1988 is a proton beam dump experiment at SIN. They found no candidate event for ${{\mathit A}^{0}}$ $\rightarrow$ ${{\mathit \gamma}}{{\mathit \gamma}}$. A standard axion decaying to 2${{\mathit \gamma}}$ is excluded except for a region $\mathit x\simeq{}$1. Lower limit on $\mathit f_{{{\mathit A}^{0}}}$ of $10^{2}-10^{3}$ GeV is given for ${\mathit m}_{{{\mathit A}^{0}}}$ = $0.1-1$ MeV.
25  BADIER 1986 did not find long-lived ${{\mathit A}^{0}}$ in 300 GeV ${{\mathit \pi}^{-}}$ Beam Dump Experiment that decays into ${{\mathit e}^{+}}{{\mathit e}^{-}}$ in the mass range ${\mathit m}_{{{\mathit A}^{0}}}$ = (20$-$200) MeV, which excludes the ${{\mathit A}^{0}}$ decay constant $\mathit f({{\mathit A}^{0}}$) in the interval (60$-$600) GeV. See their figure 6 for excluded region on $\mathit f({{\mathit A}^{0}})-{\mathit m}_{{{\mathit A}^{0}}}$ plane.
26  BERGSMA 1985 look for ${{\mathit A}^{0}}$ $\rightarrow$ 2 ${{\mathit \gamma}}$, ${{\mathit e}^{+}}{{\mathit e}^{-}}$, ${{\mathit \mu}^{+}}{{\mathit \mu}^{-}}$. First limit above is for ${\mathit m}_{{{\mathit A}^{0}}}$ = 1 MeV; second is for 200 MeV. See their figure 4 for excluded region on $\mathit f_{{{\mathit A}^{0}}}–{\mathit m}_{{{\mathit A}^{0}}}$ plane, where $\mathit f_{{{\mathit A}^{0}}}$ is ${{\mathit A}^{0}}$ decay constant. For Peccei-Quinn PECCEI 1977 ${{\mathit A}^{0}}$, ${\mathit m}_{{{\mathit A}^{0}}}$ $<$180 keV and $\tau $ $>$0.037 s. (CL = 90$\%$). For the axion of FAISSNER 1981B at 250 keV, BERGSMA 1985 expect 15 events but observe zero.
27  FAISSNER 1983 observed 19 1-${{\mathit \gamma}}$ and 12 2-${{\mathit \gamma}}$ events where a background of 4.8 and 2.3 respectively is expected. A small-angle peak is observed even if iron wall is set in front of the decay region.
28  FAISSNER 1983B extrapolate SIN ${{\mathit \gamma}}$ signal to LAMPF ${{\mathit \nu}}$ experimental condition. Resulting 370 ${{\mathit \gamma}}$'s are not at variance with LAMPF upper limit of 450 ${{\mathit \gamma}}$'s. Derived from LAMPF limit that $\lbrack{}\mathit d{\mathit \sigma (}{{\mathit A}^{0}}{)}/\mathit d\omega $ at 90$^\circ{}\rbrack{}{}{\mathit m}_{{{\mathit A}^{0}}}/{\mathit \tau}_{{{\mathit A}^{0}}}$ $<14 \times 10^{-35}$ cm${}^{2}{}$ sr${}^{-1}{}$ MeV ${}$ms${}^{-1}$. See comment on FRANK 1983B.
29  FRANK 1983B stress the importance of LAMPF data bins with negative net signal. By statistical analysis say that LAMPF and SIN-A0 are at variance when extrapolation by phase-space model is done. They find LAMPF upper limit is 248 not 450 ${{\mathit \gamma}}$'s. See comment on FAISSNER 1983B.
30  HOFFMAN 1983 set CL = 90$\%$ limit $\mathit d\sigma{}/\mathit dt{}$ B(${{\mathit e}^{+}}{{\mathit e}^{-}}$) $<3.5 \times 10^{-32}$ cm${}^{2}$/GeV${}^{2}$ for 140 $<{\mathit m}_{{{\mathit A}^{0}}}$ $<$160 MeV. Limit assumes $\tau\mathrm {({{\mathit A}^{0}})}$ $<10^{-9}$ s.
31  FETSCHER 1982 reanalyzes SIN beam-dump data of FAISSNER 1981. Claims no evidence for axion since 2-${{\mathit \gamma}}$ peak rate remarkably decreases if iron wall is set in front of the decay region.
32  FAISSNER 1981 see excess ${{\mathit \mu}}{{\mathit e}}$ events. Suggest axion interactions.
33  FAISSNER 1981B is SIN 590 MeV proton beam dump. Observed $14.5$ $\pm5.0$ events of 2${{\mathit \gamma}}$ decay of long-lived neutral penetrating particle with ${\mathit m}_{\mathrm {2{{\mathit \gamma}}}}{ {}\lesssim{} }$1 MeV. Axion interpretation with ${{\mathit \eta}}-{{\mathit A}^{0}}$ mixing gives ${\mathit m}_{{{\mathit A}^{0}}}$ = $250$ $\pm25$ keV, $\tau _{(2{{\mathit \gamma}})}$ = ($7.3$ $\pm3.7$) $ \times 10^{-3}~$s from above rate. See critical remarks below in comments of FETSCHER 1982, FAISSNER 1983, FAISSNER 1983B, FRANK 1983B, and BERGSMA 1985. Also see in the next subsection ALEKSEEV 1982B, CAVAIGNAC 1983, and ANANEV 1985.
34  KIM 1981 analyzed 8 candidates for ${{\mathit A}^{0}}$ $\rightarrow$ 2 ${{\mathit \gamma}}$ obtained by Aachen-Padova experiment at CERN with 26 GeV protons on Be. Estimated axion mass is about 300 keV and lifetime is (0.86$\sim{}5.6){\times }10^{-3}~$s depending on models. Faissner (private communication), says axion production underestimated and mass overestimated. Correct value around 200 keV.
35  FAISSNER 1980 is SIN beam dump experiment with 590 MeV protons looking for ${{\mathit A}^{0}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$ decay. Assuming ${{\mathit A}^{0}}/{{\mathit \pi}^{0}}$ = $5.5 \times 10^{-7}$, obtained decay rate limit 20/(${{\mathit A}^{0}}$ mass) MeV/s (CL = 90$\%$), which is about $10^{-7}$ below theory and interpreted as upper limit to ${\mathit m}_{{{\mathit A}^{0}}}$ $<2{}{\mathit m}_{{{\mathit e}^{-}}}$.
36  JACQUES 1980 is a BNL beam dump experiment. First limit above comes from nonobservation of excess neutral-current-type events $\lbrack{}{\mathit \sigma (}$production${)}{}{\mathit \sigma (}$interaction${)}$ $<7. \times 10^{-68}$ cm${}^{4}$, CL = 90$\%\rbrack{}$. Second limit is from nonobservation of axion decays into 2${{\mathit \gamma}}$'s or ${{\mathit e}^{+}}{{\mathit e}^{-}}$, and for axion mass a few MeV.
37  SOUKAS 1980 at BNL observed no excess of neutral-current-type events in beam dump.
38  BECHIS 1979 looked for the axion production in low energy electron Bremsstrahlung and the subsequent decay into either 2${{\mathit \gamma}}$ or ${{\mathit e}^{+}}{{\mathit e}^{-}}$. No signal found. CL = 90$\%$ limits for model parameter(s) are given.
39  COTEUS 1979 is a beam dump experiment at BNL.
40  DISHAW 1979 is a calorimetric experiment and looks for low energy tail of energy distributions due to energy lost to weakly interacting particles.
41  BELLOTTI 1978 first value comes from search for ${{\mathit A}^{0}}$ $\rightarrow$ ${{\mathit e}^{+}}{{\mathit e}^{-}}$. Second value comes from search for ${{\mathit A}^{0}}$ $\rightarrow$ 2 ${{\mathit \gamma}}$, assuming mass $<2{}{\mathit m}_{{{\mathit e}^{-}}}$. For any mass satisfying this, limit is above value${\times }$(mass${}^{-4}$). Third value uses data of PL 60B 401 and quotes ${\mathit \sigma (}$production${)}{}{\mathit \sigma (}$interaction${)}$ $<$ $10^{-67}$ cm${}^{4}$.
42  BOSETTI 1978B quotes ${\mathit \sigma (}$production${)}{}{\mathit \sigma (}$interaction${)}$ $<2. \times 10^{-67}$ cm${}^{4}$.
43  DONNELLY 1978 examines data from reactor neutrino experiments of REINES 1976 and GURR 1974 as well as SLAC beam dump experiment. Evidence is negative.
44  MICELMACHER 1978 finds no evidence of axion existence in reactor experiments of REINES 1976 and GURR 1974. (See reference under DONNELLY 1978 below).
45  VYSOTSKII 1978 derived lower limit for the axion mass 25 keV from luminosity of the sun and 200 keV from red supergiants.
References