Search for heavy lepton resonances decaying to a $Z$ boson and a lepton in $pp$ collisions at $\sqrt{s}=8$ TeV with the ATLAS detector

G. Aad (1) , S. Albrand (2) , J. Brown (2) , J. Collot (2) , S. Crépé-Renaudin (2) , P.A. Delsart (2) , C. Gabaldon (2) , M.H. Genest (2) , J.Y. Hostachy (2) , F. Ledroit-Guillon (2) , A. Lleres (2) , A. Lucotte (2) , F. Malek (2) , C. Monini (2) , J. Stark (2) , B. Trocmé (2) , M. Wu (2) , G. Rahal (3) , L. Alio (1) , M. Barbero (1) , Y. Coadou (1) , C. Diaconu (1) , Sara Diglio (1) , F. Djama (1) , O. Duccu (1) , L. Feligioni (1) , J. Gao (1) , G.D. Hallewell (1) , F. Hubaut (1) , S.J. Kahn (1) , E. B. F. G. Knoops (1) , E. Le Guirriec (1) , J. Liu (1) , K. Liu (1) , D. Madaffari (1) , K. Mochizuki (1) , E. Monnier (1) , S. Muanza (1) , Y. Nagai (1) , E. Nagy (1) , P. Pralavorio (1) , A. Rozanov , T. Serre (1) , M. Talby (1) , R.E. Ticse Torres (1) , E. Tiouchichine (1) , S. Tisserant (1) , J. Toth (1) , F. Touchard (1) , L. Vacavant (1) , Z. Barnovska (4) , N. Berger (4) , M. Delmastro (4) , L. Di Ciaccio (4) , S. Elles (4) , T. Hryn’ova (4) , S. Jézéquel (4) , I. Koletsou (4) , R. Lafaye (4) , J. Leveque (4) , N. Massol (4) , G. Sauvage (4) , E. Sauvan (4) , O. Simard (4) , T. Todorov (4) , I. Wingerter-Seez (4) , E. Yatsenko (4) , M.K. Ayoub (5) , A. Bassalat (5) , C. Becot (5) , S. Binet (5) , C. Bourdarios (5) , J.B. de Vivie De Regie (5) , D. Delgove (5) , L. Duflot (5) , M. Escalier (5) , L. Fayard (5) , D. Fournier (5) , E.L. Gkougkousis (5) , J.-F. Grivaz (5) , T. Guillemin (5) , F. Hariri (5) , S. Henrot-Versillé (5) , J. Hrivnac (5) , L. Iconomidou-Fayard (5) , M. Kado (5) , A. Lounis (5) , N. Makovec (5) , N. Morange (5) , C. Nellist (5) , L. Poggioli (5) , P. Puzo (5) , A. Renaud (5) , D. Rousseau (5) , G. Rybkin (5) , A.C. Schaffer (5) , E. Scifo (5) , L. Serin (5) , S. Simion (5) , R. Tanaka (5) , H.L. Tran (5) , D. Zerwas (5) , Zhongkai Zhang (5) , Y. Zhao (5) , D. Boumediene (6) , Emmanuel Busato (6) , D. Calvet (6) , S. Calvet (6) , J. Donini (6) , E. Dubreuil (6) , G. Gilles (6) , Ph. Gris (6) , H. Liao (6) , R. Madar (6) , D. Pallin (6) , S.M. Romano Saez (6) , C. Santoni (6) , D. Simon (6) , Timothée Theveneaux-Pelzer (6) , F. Vazeille (6)

1 CPPM - Centre de Physique des Particules de Marseille
2 LPSC - Laboratoire de Physique Subatomique et de Cosmologie
3 CC-IN2P3 - Centre de Calcul de l'IN2P3
4 LAPP - Laboratoire d'Annecy de Physique des Particules
5 LAL - Laboratoire de l'Accélérateur Linéaire
6 LPC - Laboratoire de Physique Corpusculaire - Clermont-Ferrand

A search for heavy leptons decaying to a $Z$ boson and an electron or a muon is presented. The search is based on $pp$ collision data taken at $\sqrt{s}=8$ TeV by the ATLAS experiment at the CERN Large Hadron Collider, corresponding to an integrated luminosity of 20.3 fb$^{-1}$. Three high-transverse-momentum electrons or muons are selected, with two of them required to be consistent with originating from a $Z$ boson decay. No significant excess above Standard Model background predictions is observed, and 95% confidence level limits on the production cross section of high-mass trilepton resonances are derived. The results are interpreted in the context of vector-like lepton and type-III seesaw models. For the vector-like lepton model, most heavy lepton mass values in the range 114-176 GeV are excluded. For the type-III seesaw model, most mass values in the range 100-468 GeV are excluded.

Domaines: Physique des Hautes Energies - Expérience [hep-ex]

G. Aad, S. Albrand, J. Brown, J. Collot, S. Crépé-Renaudin, et al.. Search for heavy lepton resonances decaying to a $Z$ boson and a lepton in $pp$ collisions at $\sqrt{s}=8$ TeV with the ATLAS detector. Journal of High Energy Physics, 2015, 09, pp.108. ⟨10.1007/JHEP09(2015)108⟩. ⟨in2p3-01159872⟩