# Searches for Decays of Massive ${{\boldsymbol \nu}}$ INSPIRE search

Limits on $\vert \mathit U_{{{\mathit \mu}}\mathit x}\vert ^2$ as function of ${\mathit m}_{{{\mathit \nu}_{{x}}}}$
VALUE CL% DOCUMENT ID TECN  COMMENT
• • • We do not use the following data for averages, fits, limits, etc. • • •
$<5 \times 10^{-7}$ 90 1
 1999
CCFR ${\mathit m}_{{{\mathit \nu}_{{x}}}}$=0.28 GeV
$<8 \times 10^{-8}$ 90 1
 1999
CCFR ${\mathit m}_{{{\mathit \nu}_{{x}}}}$=0.37 GeV
$<5 \times 10^{-7}$ 90 1
 1999
CCFR ${\mathit m}_{{{\mathit \nu}_{{x}}}}$= 0.50 GeV
$<6 \times 10^{-8}$ 90 1
 1999
CCFR ${\mathit m}_{{{\mathit \nu}_{{x}}}}$= 1.50 GeV
$<2 \times 10^{-5}$ 95 2
 1997 I
DLPH ${\mathit m}_{{{\mathit \nu}_{{x}}}}$=6 GeV
$<3 \times 10^{-5}$ 95 2
 1997 I
DLPH ${\mathit m}_{{{\mathit \nu}_{{x}}}}$=50 GeV
$<3 \times 10^{-6}$ 90
 1995
CNTR ${\mathit m}_{{{\mathit \nu}_{{x}}}}$ = 1 GeV
$<3 \times 10^{-5}$ 90 3
 1995 C
CHM2 ${\mathit m}_{{{\mathit \nu}_{{x}}}}$ = 2 GeV
$<6.2 \times 10^{-8}$ 95
 1990 S
L3 ${\mathit m}_{{{\mathit \nu}_{{x}}}}$=20 GeV
$<5.1 \times 10^{-10}$ 95
 1990 S
L3 ${\mathit m}_{{{\mathit \nu}_{{x}}}}$=40 GeV
$\text{all values ruled out}$ 95 4
 1990
MRK2 ${\mathit m}_{{{\mathit \nu}_{{x}}}}$ $<$ $19.6$ GeV
$<1 \times 10^{-10}$ 95 4
 1990
MRK2 ${\mathit m}_{{{\mathit \nu}_{{x}}}}$ = $22$ GeV
$<1 \times 10^{-11}$ 95 4
 1990
MRK2 ${\mathit m}_{{{\mathit \nu}_{{x}}}}$ = $41$ GeV
$\text{all values ruled out}$ 95
 1990 F
ALEP ${\mathit m}_{{{\mathit \nu}_{{x}}}}$= $25.0-42.7$ GeV
$<1 \times 10^{-13}$ 95
 1990 F
ALEP ${\mathit m}_{{{\mathit \nu}_{{x}}}}$= $42.7-45.7$ GeV
$<5 \times 10^{-3}$ 90
 1988
HRS ${\mathit m}_{{{\mathit \nu}_{{x}}}}=1.8$ GeV
$<2 \times 10^{-5}$ 90
 1988
HRS ${\mathit m}_{{{\mathit \nu}_{{x}}}}$=4 GeV
$<3 \times 10^{-6}$ 90
 1988
HRS ${\mathit m}_{{{\mathit \nu}_{{x}}}}$=6 GeV
$<1 \times 10^{-7}$ 90
 1988
CNTR ${\mathit m}_{{{\mathit \nu}_{{x}}}}$=200 MeV
$<3 \times 10^{-9}$ 90
 1988
CNTR ${\mathit m}_{{{\mathit \nu}_{{x}}}}$=300 MeV
$<4 \times 10^{-4}$ 90 5
 1987
CNTR ${\mathit m}_{{{\mathit \nu}_{{x}}}}=1.5$ GeV
$<4 \times 10^{-3}$ 90 5
 1987
CNTR ${\mathit m}_{{{\mathit \nu}_{{x}}}}=2.5$ GeV
$<0.009$ 90 5
 1987
CNTR ${\mathit m}_{{{\mathit \nu}_{{x}}}}$=5 GeV
$<0.1$ 90 5
 1987
CNTR ${\mathit m}_{{{\mathit \nu}_{{x}}}}$=10 GeV
$<8 \times 10^{-4}$ 90
 1986
CNTR ${\mathit m}_{{{\mathit \nu}_{{x}}}}$=600 MeV
$<1.2 \times 10^{-5}$ 90
 1986
CNTR ${\mathit m}_{{{\mathit \nu}_{{x}}}}=1.7$ GeV
$<3 \times 10^{-8}$ 90
 1986
CNTR ${\mathit m}_{{{\mathit \nu}_{{x}}}}$=200 MeV
$<6 \times 10^{-9}$ 90
 1986
CNTR ${\mathit m}_{{{\mathit \nu}_{{x}}}}$=350 MeV
$<1 \times 10^{-6}$ 90
 1986
CNTR ${\mathit m}_{{{\mathit \nu}_{{x}}}}$=500 MeV
$<1 \times 10^{-7}$ 90
 1986
CNTR ${\mathit m}_{{{\mathit \nu}_{{x}}}}$=1600 MeV
$<0.8 \times 10^{-5}$ 90 6
 1985
HLBC ${\mathit m}_{{{\mathit \nu}_{{x}}}}=0.4$ GeV
$<1.0 \times 10^{-7}$ 90 6
 1985
HLBC ${\mathit m}_{{{\mathit \nu}_{{x}}}}=1.5$ GeV
1  VAITAITIS 1999 search for ${{\mathit L}_{{\mu}}^{0}}$ $\rightarrow$ ${{\mathit \mu}}{{\mathit X}}$ . See paper for rather complicated limit as function of ${\mathit m}_{{{\mathit \nu}_{{x}}}}$.
2  ABREU 1997I long-lived ${{\mathit \nu}_{{x}}}$ analysis. Short-lived analysis extends limit to lower masses with decreasing sensitivity except at $3.5$ GeV, where the limit is the same as at 6 GeV.
3  VILAIN 1995C is a search for the decays of heavy isosinglet neutrinos produced by neutral current neutrino interactions. Limits were quoted for masses in the range from $0.3$ to 24 GeV. The best limit is listed above.
4  BURCHAT 1990 includes the analyses reported in JUNG 1990 , ABRAMS 1989C, and WENDT 1987 .
5  See also limits on $\vert {{\mathit U}_{{3x}}}\vert$ from WENDT 1987 .
6  COOPER-SARKAR 1985 also give limits based on model-dependent assumptions for ${{\mathit \nu}_{{\tau}}}$ flux. We do not list these. Note that for this bound to be nontrivial, $\mathit x$ is not equal to 3, i.e. ${{\mathit \nu}_{{x}}}$ cannot be the dominant mass eigenstate in ${{\mathit \nu}_{{\tau}}}$ since ${\mathit m}_{{{\mathit \nu}_{{3}}}}$ $<$70 MeV (ALBRECHT 1985I). Also, of course, $\mathit x$ is not equal to 1 or 2, so a fourth generation would be required for this bound to be nontrivial.
References:
 VAITAITIS 1999
PRL 83 4943 Search for Neutral Heavy Leptons in a High Energy Neutrino Beam
 ABREU 1997I
ZPHY C74 57 Search for Neutral Heavy Leptons Produced in ${{\mathit Z}}$ Decays
 GALLAS 1995
PR D52 6 Search for Neutral Weakly Interacting Massive Particles in the Fermilab Tevatron Wide Band Neutrino Beam
 VILAIN 1995C
PL B351 387 Search for Heavy Isosinglet Neutrinos
PL B251 321 A Search for Heavy Charged and Neutral Leptons from ${{\mathit Z}^{0}}$ Decays
 BURCHAT 1990
PR D41 3542 A Search for Decays of the ${{\mathit Z}^{0}}$ to Unstable Neutral Leptons with Mass between 2.5 and 22 GeV
 DECAMP 1990F
PL B236 511 A Search for New Quarks and Leptons from ${{\mathit Z}^{0}}$ Decay
 AKERLOF 1988
PR D37 577 Experimental Limits on Massive Neutrinos from ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Annihilation at 29 GeV
 BERNARDI 1988
PL B203 332 Further Limit on Heavy Neutrino Coupling
 MISHRA 1987
PRL 59 1397 Search for Neutral Heavy Leptons from ${{\mathit \nu}}$ Nucleus Scattering
ZPHY C31 21 Mass and Lifetime Limits on New Longlived Particles in 300 ${\mathrm {GeV/}}\mathit c$ ${{\mathit \pi}^{-}}$ Interactions
 BERNARDI 1986
PL 166B 479 Search for Neutrino Decay
 DORENBOSCH 1986
PL 166B 473 A Search for Decays of Heavy Neutrinos in the Mass Range of 0.5 $−$ 2.8 GeV
 COOPER-SARKAR 1985
PL 160B 207 Search for Heavy Neutrino Decays in the BEBC Beam Dump Experiment
 WENDT 1987
PRL 58 1810 Search for Heavy Neutrino Production in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Annihilation at 29 GeV
 JUNG 1990
PRL 64 1091 Search for Long-Lived Massive Neutrinos in ${{\mathit Z}^{0}}$ Decays
 ABRAMS 1989C
PRL 63 2447 Searches for New Quarks and Leptons Produced in ${{\mathit Z}^{0}}$ Boson Decay