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Limits on $\vert \mathit U_{{{\mathit e}}\mathit x}\vert ^2$ as Function of ${\mathit m}_{{{\mathit \nu}_{{x}}}}$

Searches for Decays of Massive ${{\mathit \nu}}$

Limits on $\vert \mathit U_{{{\mathit e}}\mathit x}\vert ^2$ 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. • •

$<1.6 \times 10^{-4}$

90

CNTR

${\mathit m}_{{{\mathit \nu}_{{x}}}}$ = 4 MeV

$<4.5 \times 10^{-5}$

90

CNTR

${\mathit m}_{{{\mathit \nu}_{{x}}}}$ = 7 MeV

$<3.8 \times 10^{-5}$

90

CNTR

${\mathit m}_{{{\mathit \nu}_{{x}}}}$ = 10 MeV

$<1.5 \times 10^{-3}$

95

L3

${\mathit m}_{{{\mathit \nu}_{{x}}}}$=80 GeV

$<0.02$

95

L3

${\mathit m}_{{{\mathit \nu}_{{x}}}}$=175 GeV

$<0.3$

95

L3

${\mathit m}_{{{\mathit \nu}_{{x}}}}$=200 GeV

$<4 \times 10^{-3}$

95

L3

${\mathit m}_{{{\mathit \nu}_{{x}}}}$=80 GeV

$<0.05$

95

L3

${\mathit m}_{{{\mathit \nu}_{{x}}}}$= 175 GeV

$<2 \times 10^{-5}$

95

DLPH

${\mathit m}_{{{\mathit \nu}_{{x}}}}$=6 GeV

$<3 \times 10^{-5}$

95

DLPH

${\mathit m}_{{{\mathit \nu}_{{x}}}}$=50 GeV

$<1.8 \times 10^{-3}$

90

MWPC

${\mathit m}_{{{\mathit \nu}_{{h}}}}$ = $1.5$ MeV

$<2.5 \times 10^{-4}$

90

MWPC

${\mathit m}_{{{\mathit \nu}_{{h}}}}$ = 4 MeV

$<4.2 \times 10^{-3}$

90

MWPC

${\mathit m}_{{{\mathit \nu}_{{h}}}}$ = 9 MeV

$<1 \times 10^{-5}$

90

${\mathit m}_{{{\mathit \nu}_{{x}}}}$=100 MeV

$<1 \times 10^{-6}$

90

${\mathit m}_{{{\mathit \nu}_{{x}}}}$= 200 MeV

$<3 \times 10^{-7}$

90

${\mathit m}_{{{\mathit \nu}_{{x}}}}$= 300 MeV

$<2 \times 10^{-7}$

90

${\mathit m}_{{{\mathit \nu}_{{x}}}}$=400 MeV

$<6.2 \times 10^{-8}$

95

L3

${\mathit m}_{{{\mathit \nu}_{{x}}}}$=20 GeV

$<5.1 \times 10^{-10}$

95

L3

${\mathit m}_{{{\mathit \nu}_{{x}}}}$=40 GeV

$\text{all values ruled out}$

95

MRK2

${\mathit m}_{{{\mathit \nu}_{{x}}}}$ $<$ $19.6$ GeV

$<1 \times 10^{-10}$

95

MRK2

${\mathit m}_{{{\mathit \nu}_{{x}}}}$= $22$ GeV

$<1 \times 10^{-11}$

95

MRK2

${\mathit m}_{{{\mathit \nu}_{{x}}}}$= $41$ GeV

$\text{all values ruled out}$

95

ALEP

${\mathit m}_{{{\mathit \nu}_{{x}}}}$= $25.0-42.7$ GeV

$<1 \times 10^{-13}$

95

ALEP

${\mathit m}_{{{\mathit \nu}_{{x}}}}$= $42.7-45.7$ GeV

$<5 \times 10^{-3}$

90

HRS

${\mathit m}_{{{\mathit \nu}_{{x}}}}=1.8$ GeV

$<2 \times 10^{-5}$

90

HRS

${\mathit m}_{{{\mathit \nu}_{{x}}}}$=4 GeV

$<3 \times 10^{-6}$

90

HRS

${\mathit m}_{{{\mathit \nu}_{{x}}}}$=6 GeV

$<1.2 \times 10^{-7}$

90

CNTR

${\mathit m}_{{{\mathit \nu}_{{x}}}}$=100 MeV

$<1 \times 10^{-8}$

90

CNTR

${\mathit m}_{{{\mathit \nu}_{{x}}}}$=200 MeV

$<2.4 \times 10^{-9}$

90

CNTR

${\mathit m}_{{{\mathit \nu}_{{x}}}}$=300 MeV

$<2.1 \times 10^{-9}$

90

CNTR

${\mathit m}_{{{\mathit \nu}_{{x}}}}$=400 MeV

$<0.02$

68

${\mathit m}_{{{\mathit \nu}_{{x}}}}=1.5$ MeV

$<8 \times 10^{-4}$

68

${\mathit m}_{{{\mathit \nu}_{{x}}}}=4.0$ MeV

$<8 \times 10^{-3}$

90

CNTR

${\mathit m}_{{{\mathit \nu}_{{x}}}}$=400 MeV

$<8 \times 10^{-5}$

90

CNTR

${\mathit m}_{{{\mathit \nu}_{{x}}}}=1.7$ GeV

$<8 \times 10^{-8}$

90

CNTR

${\mathit m}_{{{\mathit \nu}_{{x}}}}$=100 MeV

$<4 \times 10^{-8}$

90

CNTR

${\mathit m}_{{{\mathit \nu}_{{x}}}}$=200 MeV

$<6 \times 10^{-9}$

90

CNTR

${\mathit m}_{{{\mathit \nu}_{{x}}}}$=400 MeV

$<3 \times 10^{-5}$

90

CNTR

${\mathit m}_{{{\mathit \nu}_{{x}}}}$=150 MeV

$<1 \times 10^{-6}$

90

CNTR

${\mathit m}_{{{\mathit \nu}_{{x}}}}$=500 MeV

$<1 \times 10^{-7}$

90

CNTR

${\mathit m}_{{{\mathit \nu}_{{x}}}}=1.6$ GeV

$<7 \times 10^{-7}$

90

HLBC

${\mathit m}_{{{\mathit \nu}_{{x}}}}=0.4$ GeV

$<8 \times 10^{-8}$

90

HLBC

${\mathit m}_{{{\mathit \nu}_{{x}}}}=1.5$ GeV

$<0.01$

90

CNTR

${\mathit m}_{{{\mathit \nu}_{{x}}}}$=10 MeV

$<1 \times 10^{-5}$

90

CNTR

${\mathit m}_{{{\mathit \nu}_{{x}}}}$=110 MeV

$<6 \times 10^{-7}$

90

CNTR

${\mathit m}_{{{\mathit \nu}_{{x}}}}$=410 MeV

$<1 \times 10^{-5}$

90

${\mathit m}_{{{\mathit \nu}_{{x}}}}$=160 MeV

$<1 \times 10^{-6}$

90

${\mathit m}_{{{\mathit \nu}_{{x}}}}$=480 MeV

¹

BACK 2003A searched for heavy neutrinos emitted from ${}^{8}\mathrm {B}$ decay in the Sun using the decay ${{\mathit \nu}_{{h}}}$ $\rightarrow$ ${{\mathit \nu}_{{e}}}{{\mathit e}^{+}}{{\mathit e}^{-}}$ in the Counting Test Facility (the prototype of the Borexino detector) and obtained limits on heavy neutrino admixture for the ${{\mathit \nu}_{{h}}}$ mass range $1.1 - 12$ MeV.

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	HAGNER 1995 obtain limits on heavy neutrino admixture from the decay ${{\mathit \nu}_{{h}}}$ $\rightarrow$ ${{\mathit \nu}_{{e}}}{{\mathit e}^{+}}{{\mathit e}^{-}}$ at a nuclear reactor for the ${{\mathit \nu}_{{h}}}$ mass range $2 - 9$ MeV.

⁴	BARANOV 1993 is a search for neutrino decays into ${{\mathit e}^{+}}{{\mathit e}^{-}}{{\mathit \nu}_{{e}}}$ using a beam dump experiment at the 70 GeV Serpukhov proton synchrotron. The limits are not as good as those achieved earlier by BERGSMA 1983 and BERNARDI 1986 , BERNARDI 1988 .

⁵	BURCHAT 1990 includes the analyses reported in JUNG 1990 , ABRAMS 1989C, and WENDT 1987 .

⁶	OBERAUER 1987 bounds from search for ${{\mathit \nu}}$ $\rightarrow$ ${{\mathit \nu}^{\,'}}{{\mathit e}}{{\mathit e}}$ decay mode using reactor (anti)neutrinos.

⁷

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.

⁸

BERGSMA 1983B also quote limits on $\vert \mathit U_{{{\mathit e}}3}\vert {}^{2}$ where the index 3 refers to the mass eigenstate dominantly coupled to the ${{\mathit \tau}}$. Those limits were based on assumptions about the ${{\mathit D}_{{s}}}$ mass and ${{\mathit D}_{{s}}}$ $\rightarrow$ ${{\mathit \tau}}{{\mathit \nu}_{{\tau}}}$ branching ratio which are no longer valid. See COOPER-SARKAR 1985 .

References:

JETPL 78 261

New Experimental Limits on Heavy Neutrino Mixing in ${}^{8}\mathrm {B}$ Decay Obtained with the Borexino Counting Test Facility

PL B517 67

Search for Heavy Isosinglet Neutrino in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Annihilation at LEP

PL B461 397

Search for Heavy Isosinglet Neutrinos in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Annihilation at 130 $<$ $\sqrt {s }$ $<$ 189 GeV

ZPHY C74 57

Search for Neutral Heavy Leptons Produced in ${{\mathit Z}}$ Decays

ZPHY C75 580 (errat.)

Erratum: ABREU 1997I Search for Neutral Heavy Leptons Produced in ${{\mathit Z}}$ Decays

PR D52 1343

Experimental Search for the Neutrino Decay ${{\mathit \nu}}$ $\rightarrow$ ${{\mathit \nu}}{{\mathit e}^{+}}{{\mathit e}^{-}}$ and Limits on Neutrino Mixing

PL B302 336

Search for Heavy Neutrinos at the IHEP-JINR Neutrino Detector

PL B251 321

A Search for Heavy Charged and Neutral Leptons from ${{\mathit Z}^{0}}$ Decays

PR D41 3542

A Search for Decays of the ${{\mathit Z}^{0}}$ to Unstable Neutral Leptons with Mass between 2.5 and 22 GeV

PL B236 511

A Search for New Quarks and Leptons from ${{\mathit Z}^{0}}$ Decay

PR D37 577

Experimental Limits on Massive Neutrinos from ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Annihilation at 29 GeV

PL B203 332

Further Limit on Heavy Neutrino Coupling

PL B198 113

Experimental Limits on the Decay of Reactor Neutrinos

ZPHY C31 21

Mass and Lifetime Limits on New Longlived Particles in 300 ${\mathrm {GeV/}}\mathit c$ ${{\mathit \pi}^{-}}$ Interactions

PL 166B 479

Search for Neutrino Decay

PL 166B 473

A Search for Decays of Heavy Neutrinos in the Mass Range of 0.5 $−$ 2.8 GeV

PL 160B 207

Search for Heavy Neutrino Decays in the BEBC Beam Dump Experiment

PL 128B 361

A Search for Decays of Heavy Neutrinos

PR D28 2762

Limits on the Mixings of Heavy Decaying Neutrinos

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