Search for long-lived neutral particles decaying to quark-antiquark pairs in proton-proton collisions at sqrt(s) = 8 TeV

V. Khachatryan , M. Besancon (1) , F. Couderc (1) , M. Dejardin (1) , D. Denegri (1) , B. Fabbro (1) , J.L. Faure (1) , C. Favaro (1) , F. Ferri (1) , S. Ganjour (1) , A. Givernaud (1) , P. Gras (1) , G. Hamel De Monchenault (1) , P. Jarry (1) , E. Locci (1) , J. Malcles (1) , J. Rander (1) , A. Rosowsky (1) , M. Titov (1) , S. Baffioni (2) , F. Beaudette (2) , P. Busson (2) , C. Charlot (2) , T. Dahms (2) , M. Dalchenko (2) , L. Dobrzynski (2) , N. Filipovic (2) , A. Florent (2) , R. Granier De Cassagnac (2) , L. Mastrolorenzo (2) , P. Miné (2) , C. Mironov (2) , I.N. Naranjo (2) , M. Nguyen (2) , C. Ochando (2) , P. Paganini (2) , S. Regnard (2) , R. Salerno (2) , J.B. Sauvan (2) , Y. Sirois (2) , C. Veelken (2) , Y. Yilmaz (2) , A. Zabi (2) , J.-L. Agram (3) , J. Andrea (3) , A. Aubin (3) , D. Bloch (3) , J.-M. Brom (3) , E.C. Chabert (3) , C. Collard (3) , E. Conte (3) , J.-C. Fontaine (3) , D. Gelé́ , U. Goerlach (3) , C. Goetzmann (3) , A.-C. Le Bihan (3) , P. Van Hove (3) , S. Gadrat (4) , S. Beauceron (5) , N. Beaupere (5) , G. Boudoul (5) , E. Bouvier (5) , S. Brochet (5) , C.A. Carrillo Montoya (5) , J. Chasserat (5) , R. Chierici (5) , D. Contardo (5) , P. Depasse (5) , H. El Mamouni (5) , J. Fan (5) , J. Fay (5) , S. Gascon (5) , M. Gouzevitch (5) , B. Ille (5) , T. Kurca (5) , M. Lethuillier (5) , L. Mirabito (5) , S. Perries (5) , J.D. Ruiz Alvarez (5) , D. Sabes (5) , L. Sgandurra (5) , V. Sordini (5) , M. Vander Donckt (5) , P. Verdier (2) , S. Viret (5) , H. Xiao (5)

1 IRFU - Institut de Recherches sur les lois Fondamentales de l'Univers
2 LLR - Laboratoire Leprince-Ringuet
3 IPHC - Institut Pluridisciplinaire Hubert Curien
4 CC-IN2P3 - Centre de Calcul de l'IN2P3
5 IPNL - Institut de Physique Nucléaire de Lyon

A search is performed for long-lived massive neutral particles decaying to quark-antiquark pairs. The experimental signature is a distinctive topology of a pair of jets, originating at a secondary vertex. Events were collected with the CMS detector at the CERN LHC in proton-proton collisions at a centre-of-mass energy of 8 TeV. The data analyzed correspond to an integrated luminosity of 18.5 inverse femtobarns. No significant excess is observed above standard model expectations. Upper limits at 95% confidence level are set on the production cross section of a heavy neutral scalar particle, H, in the mass range of 200 to 1000 GeV, decaying promptly into a pair of long-lived neutral X particles in the mass range of 50 to 350 GeV, each in turn decaying into a quark-antiquark pair. For X with mean proper decay lengths of 0.4 to 200 cm, the upper limits are typically 0.5-200 fb. The results are also interpreted in the context of an R-parity-violating supersymmetric model with long-lived neutralinos decaying into a quark-antiquark pair and a muon. For pair production of squarks that promptly decay to neutralinos with mean proper decay lengths of 2-40 cm, the upper limits on the cross section are typically 0.5-3 fb. The above limits are the most stringent on these channels to date.

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

V. Khachatryan, M. Besancon, F. Couderc, M. Dejardin, D. Denegri, et al.. Search for long-lived neutral particles decaying to quark-antiquark pairs in proton-proton collisions at sqrt(s) = 8 TeV. Physical Review D, 2015, 91, pp.012007. ⟨10.1103/PhysRevD.91.012007⟩. ⟨in2p3-01091412⟩