Measurements of Higgs boson production and couplings in the four-lepton channel in pp collisions at center-of-mass energies of 7 and 8 TeV with the ATLAS detector

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) , 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) , 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) , S. Abdel Khalek (5) , A. Bassalat (5) , C. Becot (5) , S. Binet (5) , C. Bourdarios (5) , D. Charfeddine (5) , J.B. de Vivie de Regie (5) , L. Duflot (5) , M. Escalier (5) , L. Fayard (5) , D. Fournier (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) , 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) , Z. Zhang (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) , S. Muanza (1) , Y. Nagai (1) , P. Pralavorio (1) , A. Rozanov (1) , T. Serre (1) , M. Talby (1) , E. Tiouchichine (1) , S. Tisserant (1) , J. Toth (1) , F. Touchard (1) , M. Ughetto (1) , L. Vacavant (1) , Z. Barnovska (6) , N. Berger (6) , M. Delmastro (6) , L. Di Ciaccio (6) , S. Elles (6) , C. Goy (6) , T. Hryn'Ova (6) , S. Jézéquel (6) , H. Keoshkerian (6) , I. Koletsou (6) , R. Lafaye (6) , J. Leveque (6) , V.P. Lombardo (6) , N. Massol (6) , H. Przysiezniak (6) , G. Sauvage (6) , E. Sauvan (6) , M. Schwoerer (6) , O. Simard (6) , T. Todorov (6) , I. Wingerter-Seez (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 LPC - Laboratoire de Physique Corpusculaire - Clermont-Ferrand
5 LAL - Laboratoire de l'Accélérateur Linéaire
6 LAPP - Laboratoire d'Annecy de Physique des Particules

The final ATLAS Run 1 measurements of Higgs boson production and couplings in the decay channel $H\to ZZ^{*}\to\ell^+\ell^-\ell^{'+}\ell^{'-}$, where $\ell,\ell^{'}=e$ or $\mu$, are presented. These measurements were performed using $pp$ collision data corresponding to integrated luminosities of 4.5 fb$^{-1}$ and 20.3 fb$^{-1}$ at center-of-mass energies of 7 TeV and 8 TeV, respectively, recorded with the ATLAS detector at the LHC. The $H\to ZZ^{*}\to 4\ell$ signal is observed with a significance of 8.1 standard deviations at 125.36 GeV, the combined ATLAS measurement of the Higgs boson mass from the $H\rightarrow \gamma\gamma$ and $H\to ZZ^{*}\to 4\ell$ channels. The production rate relative to the Standard Model expectation, the signal strength, is measured in four different production categories in the $H\to ZZ^{*}\to 4\ell$ channel. The measured signal strength, at this mass, and with all categories combined, is 1.44 $^{+0.40}_{-0.33}$. The signal strength for Higgs boson production in gluon fusion or in association with $t\bar{t}$ or $b\bar{b}$ pairs is found to be 1.7 $^{+0.5}_{-0.4}$, while the signal strength for vector-boson fusion combined with $WH/ZH$ associated production is found to be 0.3 $^{+1.6}_{-0.9}$.

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

G. Aad, S. Albrand, J. Brown, J. Collot, S. Crépé-Renaudin, et al.. Measurements of Higgs boson production and couplings in the four-lepton channel in pp collisions at center-of-mass energies of 7 and 8 TeV with the ATLAS detector. Physical Review D, 2015, 91 (1), pp.012006. ⟨10.1103/PhysRevD.91.012006⟩. ⟨in2p3-01057655⟩