Weak isosinglet Neutral Heavy Leptons (nu(m)) have been searched for using data collected by the DELPHI detector corresponding to 3.3 x 10(6) hadronic Z(0) decays at LEP1. Four separate searches have been performed, for short-lived nu(m) production giving monojet or acollinear jet topologies, and for long-lived nu(m) giving detectable secondary vertices or calorimeter clusters, No indication of the existence of these particles has been found, leading to an upper limit for the branching ratio BR(Z(0) --> nu(m)<(nu)over bar>) of about 1.3 x 10(-6) at 95% confidence level for nu(m) masses between 3.5 and 50 GeV/c(2). Outside this range the limit weakens rapidly with the nu(m) mass. The results are also interpreted in terms of Limits for the single production of excited neutrinos.

Search for neutral heavy leptons produced in Z decays

GASPARINI, UGO;MARGONI, MARTINO;RONCHESE, PAOLO;SIMONETTO, FRANCO;ZUMERLE, GIANNI
1997

Abstract

Weak isosinglet Neutral Heavy Leptons (nu(m)) have been searched for using data collected by the DELPHI detector corresponding to 3.3 x 10(6) hadronic Z(0) decays at LEP1. Four separate searches have been performed, for short-lived nu(m) production giving monojet or acollinear jet topologies, and for long-lived nu(m) giving detectable secondary vertices or calorimeter clusters, No indication of the existence of these particles has been found, leading to an upper limit for the branching ratio BR(Z(0) --> nu(m)<(nu)over bar>) of about 1.3 x 10(-6) at 95% confidence level for nu(m) masses between 3.5 and 50 GeV/c(2). Outside this range the limit weakens rapidly with the nu(m) mass. The results are also interpreted in terms of Limits for the single production of excited neutrinos.
File in questo prodotto:
Non ci sono file associati a questo prodotto.
Pubblicazioni consigliate

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/2500431
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 279
  • ???jsp.display-item.citation.isi??? 191
social impact