Heavy Neutral Lepton MASS LIMITS INSPIRE search

Dirac coupling to ${{\mathit e}}$

$\bf{>101.5}$

Dirac coupling to ${{\mathit \mu}}$

$\bf{>90.3}$

Dirac coupling to ${{\mathit \tau}}$

$\bf{>89.5}$

Majorana coupling to ${{\mathit e}}$

$\bf{>90.7}$

Majorana coupling to ${{\mathit \mu}}$

$\bf{>80.5}$

Majorana coupling to ${{\mathit \tau}}$

• • • We do not use the following data for averages, fits, limits, etc. • • •

$>76.0$

OPAL

Majorana, coupling to ${{\mathit e}}$

$>88.0$

OPAL

Dirac, coupling to ${{\mathit e}}$

$>76.0$

OPAL

Majorana, coupling to ${{\mathit \mu}}$

$>88.1$

OPAL

Dirac, coupling to ${{\mathit \mu}}$

$>53.8$

OPAL

Majorana, coupling to ${{\mathit \tau}}$

$>71.1$

OPAL

Dirac, coupling to ${{\mathit \tau}}$

$>76.5$

1999

DLPH

Dirac coupling to ${{\mathit e}}$

$>79.5$

1999

DLPH

Dirac coupling to ${{\mathit \mu}}$

$>60.5$

1999

DLPH

Dirac coupling to ${{\mathit \tau}}$

$>63$

¹ ^{, 2}

BUSKULIC

1996

ALEP

Dirac

$>54.3$

¹ ^{, 3}

BUSKULIC

1996

ALEP

Majorana

¹ BUSKULIC 1996S requires the decay length of the heavy lepton to be $<1~$cm, limiting the square of the mixing angle $\vert \mathit U_{ {{\mathit \ell}} {{\mathit j}} }\vert ^2$ to $10^{-10}$.

² BUSKULIC 1996S limit for mixing with ${{\mathit \tau}}$. Mass is $>63.6$ GeV for mixing with ${{\mathit e}}$ or ${{\mathit \mu}}$.

³ BUSKULIC 1996S limit for mixing with ${{\mathit \tau}}$. Mass is $>55.2$ GeV for mixing with ${{\mathit e}}$ or ${{\mathit \mu}}$.

References:

2001B

PL B517 75

Search for Heavy Neutral and Charged Leptons in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Annihilation at LEP

2000I

EPJ C14 73

Search for Unstable Heavy and Excited Leptons at LEP-2