Heavy Neutral Lepton MASS LIMITS

INSPIRE   PDGID:
S077MN
Limits apply only to heavy lepton type given in comment at right of data Listings.

See the “Quark and Lepton Compositeness, Searches for” Listings for limits on radiatively decaying excited neutral leptons, $\mathit i.e.$ ${{\mathit \nu}^{*}}$ $\rightarrow$ ${{\mathit \nu}}{{\mathit \gamma}}$ .

VALUE (GeV) CL% DOCUMENT ID TECN  COMMENT
$\bf{>101.3}$ 95
ACHARD
2001B
 L3 Dirac coupling to ${{\mathit e}}$
$\bf{>101.5}$ 95
ACHARD
2001B
 L3 Dirac coupling to ${{\mathit \mu}}$
$\bf{>90.3}$ 95
ACHARD
2001B
 L3 Dirac coupling to ${{\mathit \tau}}$
$\bf{>89.5}$ 95
ACHARD
2001B
 L3 Majorana coupling to ${{\mathit e}}$
$\bf{>90.7}$ 95
ACHARD
2001B
 L3 Majorana coupling to ${{\mathit \mu}}$
$\bf{>80.5}$ 95
ACHARD
2001B
 L3 Majorana coupling to ${{\mathit \tau}}$
• • We do not use the following data for averages, fits, limits, etc. • •
$>76.0$ 95
ABBIENDI
2000I
 OPAL Majorana, coupling to ${{\mathit e}}$
$>88.0$ 95
ABBIENDI
2000I
 OPAL Dirac, coupling to ${{\mathit e}}$
$>76.0$ 95
ABBIENDI
2000I
 OPAL Majorana, coupling to ${{\mathit \mu}}$
$>88.1$ 95
ABBIENDI
2000I
 OPAL Dirac, coupling to ${{\mathit \mu}}$
$>53.8$ 95
ABBIENDI
2000I
 OPAL Majorana, coupling to ${{\mathit \tau}}$
$>71.1$ 95
ABBIENDI
2000I
 OPAL Dirac, coupling to ${{\mathit \tau}}$
$>76.5$ 95
ABREU
1999O
 DLPH Dirac coupling to ${{\mathit e}}$
$>79.5$ 95
ABREU
1999O
 DLPH Dirac coupling to ${{\mathit \mu}}$
$>60.5$ 95
ABREU
1999O
 DLPH Dirac coupling to ${{\mathit \tau}}$
$>63$ 95 1, 2
BUSKULIC
1996S
 ALEP Dirac
$>54.3$ 95 1, 3
BUSKULIC
1996S
 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:
ACHARD 2001B
PL B517 75 Search for Heavy Neutral and Charged Leptons in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Annihilation at LEP
ABBIENDI 2000I
EPJ C14 73 Search for Unstable Heavy and Excited Leptons at LEP-2
ABREU 1999O
EPJ C8 41 Search for Composite and Exotic Fermions at LEP-2
BUSKULIC 1996S
PL B384 439 Search for Heavy Lepton Pair Production in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Collisions at the Centre-of-Mass Energies of 130 and 136 GeV