Measurement of the 4l Cross Section at the Z Resonance and Determination of the Branching Fraction of Z->4l in pp Collisions at sqrt(s) = 7 and 8 TeV with ATLAS

G. Aad (1) , S. Albrand (2) , J. Brown (2) , J. Collot (2) , S. Crépé-Renaudin (2) , B. Dechenaux (2) , P.A. Delsart (2) , C. Gabaldon (2) , M.H. Genest (2) , J.Y. Hostachy (2) , B.T. Le (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) , S. Abdel Khalek (3) , E. Augé (3) , A. Bassalat (3) , C. Becot (3) , S. Binet (3) , C. Bourdarios (3) , D. Charfeddine (3) , C. de La Taille (3) , J.B. de Vivie de Regie (3) , L. Duflot (3) , M. Escalier (3) , L. Fayard (3) , D. Fournier (3) , J.-F. Grivaz (3) , T. Guillemin (3) , S. Henrot-Versillé (3) , J. Hrivnac (3) , L. Iconomidou-Fayard (3) , J. Idarraga (3) , M. Kado (3) , Y. Li (3) , A. Lounis (3) , N. Makovec (3) , P. Matricon (3) , L. Poggioli (3) , P. Puzo (3) , A. Renaud (3) , D. Rousseau (3) , G. Rybkin (3) , A.C. Schaffer (3) , E. Scifo (3) , L. Serin (3) , S. Simion (3) , R. Tanaka (3) , H.L. Tran (3) , D. Zerwas (3) , Zhiqing Zhang (3) , D. Boumediene (4) , Emmanuel Busato (4) , D. Calvet (4) , S. Calvet (4) , J. Donini (4) , E. Dubreuil (4) , N. Ghodbane (4) , G. Gilles (4) , Ph. Gris (4) , C. Guicheney (4) , H. Liao (4) , D. Pallin (4) , Daniela Paredes Hernández (4) , F. Podlyski (4) , C. Santoni (4) , Timothée Theveneaux-Pelzer (4) , Loïc Valery (4) , F. Vazeille (4) , Z. Barnovska (5) , N. Berger (5) , M. Delmastro (5) , L. Di Ciaccio (5) , T.K.O. Doan (5) , S. Elles (5) , C. Goy (5) , T. Hryn'Ova (5) , S. Jézéquel (5) , H. Keoshkerian (5) , R. Lafaye (5) , J. Leveque (5) , N. Massol (5) , H. Przysiezniak (5) , G. Sauvage (5) , E. Sauvan (5) , M. Schwoerer (5) , T. Todorov (5) , I. Wingerter-Seez (5) , L. Alio (1) , M. Barbero (1) , C. Bertella (1) , J. C. Clémens (1) , Y. Coadou (1) , Sara Diglio (1) , F. Djama (1) , L. Feligioni (1) , D. Hoffmann (1) , F. Hubaut (1) , E. B. F. G. Knoops (1) , E. Le Guirriec (1) , B. Li (1) , D. Madaffari (1) , K. Mochizuki (1) , E. Monnier (1) , Y. Nagai (1) , P. Pralavorio (1) , A. Rozanov (1) , T. Serre (1) , M. Talby (1) , N. Tannoury (1) , E. Tiouchichine (1) , S. Tisserant (1) , J. Toth (1) , F. Touchard (1) , M. Ughetto (1) , L. Vacavant (1) , I. Koletsou (5) , O. Simard (5)

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

Measurements of four-lepton (4$\ell$, $\ell=e,\mu$) production cross sections at the $Z$ resonance in $pp$ collisions at the LHC with the ATLAS detector are presented. For dilepton and four-lepton invariant mass region $m_{\ell^+\ell^-} > 5$ GeV and $80 < m_{4\ell} < 100$ GeV, the measured cross sections are $76 \pm 18 \text { (stat) } \pm 4 \text { (syst) } \pm 1.4 \text { (lumi) }$ fb and $107 \pm 9 \text{ (stat) } \pm 4 \text{ (syst) } \pm 3.0 \text { (lumi) }$ fb at $\sqrt s$ = 7 and 8 TeV, respectively. By subtracting the non-resonant 4$\ell$ production contributions and normalizing with $Z\rightarrow \mu^+\mu^-$ events, the branching fraction for the $Z$ boson decay to $4\ell$ is determined to be $\left( 3.20 \pm 0.25\text{ (stat)} \pm 0.13\text{ (syst)} \right) \times 10^{-6}$, consistent with the Standard Model prediction.

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

G. Aad, S. Albrand, J. Brown, J. Collot, S. Crépé-Renaudin, et al.. Measurement of the 4l Cross Section at the Z Resonance and Determination of the Branching Fraction of Z->4l in pp Collisions at sqrt(s) = 7 and 8 TeV with ATLAS. Physical Review Letters, 2014, 112, pp.231806. ⟨in2p3-01006480v1⟩