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Search for the standard model Higgs boson produced in association with a top-quark pair in pp collisions at the LHC

Journal of High Energy Physics 2013:5 (2013)

Authors:

S Chatrchyan, V Khachatryan, AM Sirunyan, A Tumasyan, W Adam, T Bergauer, M Dragicevic, J Erö, C Fabjan, M Friedl, R Frühwirth, VM Ghete, N Hörmann, J Hrubec, M Jeitler, W Kiesenhofer, V Knünz, M Krammer, I Krätschmer, D Liko, I Mikulec, D Rabady, B Rahbaran, C Rohringer, H Rohringer, R Schöfbeck, J Strauss, A Taurok, W Treberer-Treberspurg, W Waltenberger, CE Wulz, V Mossolov, N Shumeiko, J Suarez Gonzalez, S Alderweireldt, M Bansal, S Bansal, T Cornelis, EA De Wolf, X Janssen, A Knutsson, S Luyckx, L Mucibello, S Ochesanu, B Roland, R Rougny, H Van Haevermaet, P Van Mechelen, N Van Remortel, A Van Spilbeeck, F Blekman, S Blyweert, J D'hondt, R Gonzalez Suarez, A Kalogeropoulos, J Keaveney, M Maes, A Olbrechts, S Tavernier, W Van Doninck, P Van Mulders, GP Van Onsem, I Villella, B Clerbaux, G De Lentdecker, V Dero, APR Gay, T Hreus, A Léonard, PE Marage, A Mohammadi, T Reis, L Thomas, C Vander Velde, P Vanlaer, J Wang, V Adler, K Beernaert, L Benucci, A Cimmino, S Costantini, G Garcia, M Grunewald, B Klein, J Lellouch, A Marinov, J Mccartin, AA Ocampo Rios, D Ryckbosch, M Sigamani, N Strobbe, F Thyssen, M Tytgat, S Walsh, E Yazgan, N Zaganidis, S Basegmez, G Bruno, R Castello, L Ceard

Abstract:

A search for the standard model Higgs boson produced in association with a top-quark pair is presented using data samples corresponding to an integrated luminosity of 5.0 fb-1 (5.1 fb-1) collected in pp collisions at the center-of-mass energy of 7 TeV (8 TeV). Events are considered where the top-quark pair decays to either one lepton+jets (tt̄ → ℓvqq̄bb̄) or dileptons (tt̄ → ℓ+vl- rfvn1̄bb̄), ℓ being an electron or a muon. The search is optimized for the decay mode H → bb̄. The largest background to the tt̄H signal is top-quark pair production with additional jets. Artificial neural networks are used to discriminate between signal and background events. Combining the results from the 7 TeV and 8 TeV samples, the observed (expected) limit on the cross section for Higgs boson production in association with top-quark pairs for a Higgs boson mass of 125 GeV is 5.8 (5.2) times the standard model expectation. [Figure not available: see fulltext.] © 2013 Cern for the benefit of the CMS collaboration.
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Search for third generation scalar leptoquarks in pp collisions at √s=7 TeV with the ATLAS detector

Journal of High Energy Physics 2013:6 (2013)

Authors:

G Aad, T Abajyan, B Abbott, J Abdallah, SA Khalek, AA Abdelalim, O Abdinov, R Aben, B Abi, M Abolins, OS Abouzeid, H Abramowicz, H Abreu, BS Acharya, L Adamczyk, DL Adams, TN Addy, J Adelman, S Adomeit, P Adragna, T Adye, S Aefsky, JA Aguilar-Saavedra, M Agustoni, M Aharrouche, SP Ahlen, F Ahles, A Ahmad, M Ahsan, G Aielli, TPA Åkesson, G Akimoto, AV Akimov, MA Alam, J Albert, S Albrand, M Aleksa, IN Aleksandrov, F Alessandria, C Alexa, G Alexander, G Alexandre, T Alexopoulos, M Alhroob, M Aliev, G Alimonti, J Alison, BMM Allbrooke, PP Allport, SE Allwood-Spiers, J Almond, A Aloisio, R Alon, A Alonso, F Alonso, A Altheimer, BA Gonzalez, MG Alviggi, K Amako, C Amelung, VV Ammosov, SP Amor Dos Santos, A Amorim, N Amram, C Anastopoulos, LS Ancu, N Andari, T Andeen, CF Anders, G Anders, KJ Anderson, A Andreazza, V Andrei, ML Andrieux, XS Anduaga, S Angelidakis, P Anger, A Angerami, F Anghinolfi, A Anisenkov, N Anjos, A Annovi, A Antonaki, M Antonelli, A Antonov, J Antos, F Anulli, M Aoki, S Aoun, LA Bella, R Apolle, G Arabidze, I Aracena, Y Arai, ATH Arce, S Arfaoui, JF Arguin, S Argyropoulos, E Arik, M Arik

Abstract:

A search for pair-produced third generation scalar leptoquarks is presented, using proton-proton collisions at s=7 TeV at the LHC. The data were recorded with the ATLAS detector and correspond to an integrated luminosity of 4.7 fb-1. Each leptoquark is assumed to decay to a tau lepton and a b-quark with a branching fraction equal to 100%. No statistically significant excess above the Standard Model expectation is observed. Third generation leptoquarks are therefore excluded at 95% confidence level for masses less than 534GeV. [Figure not available: see fulltext.] © 2013 Cern for the benefit of the ATLAS collaboration.
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Searches for long-lived charged particles in pp collisions at □ =7 and 8 TeV

Journal of High Energy Physics 2013:7 (2013)

Authors:

S Chatrchyan, V Khachatryan, AM Sirunyan, A Tumasyan, W Adam, T Bergauer, M Dragicevic, J Erö, C Fabjan, M Friedl, R Frühwirth, VM Ghete, N Hörmann, J Hrubec, M Jeitler, W Kiesenhofer, V Knünz, M Krammer, I Krätschmer, D Liko, I Mikulec, D Rabady, B Rahbaran, C Rohringer, H Rohringer, R Schöfbeck, J Strauss, A Taurok, W Treberer-Treberspurg, W Waltenberger, CE Wulz, V Mossolov, N Shumeiko, J Suarez Gonzalez, S Alderweireldt, M Bansal, S Bansal, T Cornelis, EA De Wolf, X Janssen, A Knutsson, S Luyckx, L Mucibello, S Ochesanu, B Roland, R Rougny, H Van Haevermaet, P Van Mechelen, N Van Remortel, A Van Spilbeeck, F Blekman, S Blyweert, J D'hondt, A Kalogeropoulos, J Keaveney, M Maes, A Olbrechts, S Tavernier, W Van Doninck, P Van Mulders, GP Van Onsem, I Villella, B Clerbaux, G De Lentdecker, L Favart, APR Gay, T Hreus, A Léonard, PE Marage, A Mohammadi, L Perniè, T Reis, T Seva, L Thomas, C Vander Velde, P Vanlaer, J Wang, V Adler, K Beernaert, L Benucci, A Cimmino, S Costantini, S Dildick, G Garcia, B Klein, J Lellouch, A Marinov, J Mccartin, AA Ocampo Rios, D Ryckbosch, M Sigamani, N Strobbe, F Thyssen, M Tytgat, S Walsh, E Yazgan, N Zaganidis, S Basegmez, C Beluffi, G Bruno

Abstract:

Abstract: Results of searches for heavy stable charged particles produced in pp collisions at □ = 7 and 8 TeV are presented corresponding to an integrated luminosity of 5.0 fb-1 and 18.8 fb-1, respectively. Data collected with the CMS detector are used to study the momentum, energy deposition, and time-of-flight of signal candidates. Leptons with an electric charge between e/3 and 8e, as well as bound states that can undergo charge exchange with the detector material, are studied. Analysis results are presented for various combinations of signatures in the inner tracker only, inner tracker and muon detector, and muon detector only. Detector signatures utilized are long time-of-flight to the outer muon system and anomalously high (or low) energy deposition in the inner tracker. The data are consistent with the expected background, and upper limits are set on the production cross section of long-lived gluinos, scalar top quarks, and scalar τ leptons, as well as pair produced long-lived leptons. Corresponding lower mass limits, ranging up to 1322 GeV/c 2 for gluinos, are the most stringent to date. [Figure not available: see fulltext.] © 2013 Cern for the benefit of the CMS collaboration.
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Studies of jet mass in dijet and W/Z + jet events

Journal of High Energy Physics 2013:5 (2013)

Authors:

S Chatrchyan, V Khachatryan, AM Sirunyan, A Tumasyan, W Adam, E Aguilo, T Bergauer, M Dragicevic, J Erö, C Fabjan, M Friedl, R Frühwirth, VM Ghete, N Hörmann, J Hrubec, M Jeitler, W Kiesenhofer, V Knünz, M Krammer, I Krätschmer, D Liko, I Mikulec, M Pernicka, D Rabady, B Rahbaran, C Rohringer, H Rohringer, R Schöfbeck, J Strauss, A Taurok, W Waltenberger, CE Wulz, V Mossolov, N Shumeiko, J Suarez Gonzalez, S Alderweireldt, M Bansal, S Bansal, T Cornelis, EA De Wolf, X Janssen, S Luyckx, L Mucibello, S Ochesanu, B Roland, R Rougny, H Van Haevermaet, P Van Mechelen, N Van Remortel, A Van Spilbeeck, F Blekman, S Blyweert, J D'hondt, R Gonzalez Suarez, A Kalogeropoulos, M Maes, A Olbrechts, S Tavernier, W Van Doninck, P Van Mulders, GP Van Onsem, I Villella, B Clerbaux, G De Lentdecker, V Dero, APR Gay, T Hreus, A Léonard, PE Marage, A Mohammadi, T Reis, L Thomas, C Vander Velde, P Vanlaer, J Wang, V Adler, K Beernaert, A Cimmino, S Costantini, G Garcia, M Grunewald, B Klein, J Lellouch, A Marinov, J Mccartin, AA Ocampo Rios, D Ryckbosch, M Sigamani, N Strobbe, F Thyssen, M Tytgat, S Walsh, E Yazgan, N Zaganidis, S Basegmez, G Bruno, R Castello, L Ceard, C Delaere, T Du Pree

Abstract:

Invariant mass spectra for jets reconstructed using the anti-k T and CambridgeAachen algorithms are studied for different jet "grooming" techniques in data corresponding to an integrated luminosity of 5 fb-1, recorded with the CMS detector in proton-proton collisions at the LHC at a center-of-mass energy of 7 TeV. Leading-order QCD predictions for inclusive dijet and W/Z+jet production combined with parton-shower Monte Carlo models are found to agree overall with the data, and the agreement improves with the implementation of jet grooming methods used to distinguish merged jets of large transverse momentum from softer QCD gluon radiation. © 2013 CERN for the benefit of the CMS collaboration.
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Study of exclusive two-photon production of W+W- in pp collisions at √s=7 TeV and constraints on anomalous quartic gauge couplings

Journal of High Energy Physics 2013:7 (2013)

Authors:

S Chatrchyan, V Khachatryan, AM Sirunyan, A Tumasyan, W Adam, T Bergauer, M Dragicevic, J Erö, C Fabjan, M Friedl, R Frühwirth, VM Ghete, N Hörmann, J Hrubec, M Jeitler, W Kiesenhofer, V Knünz, M Krammer, I Krätschmer, D Liko, I Mikulec, D Rabady, B Rahbaran, C Rohringer, H Rohringer, R Schöfbeck, J Strauss, A Taurok, W Treberer-Treberspurg, W Waltenberger, CE Wulz, V Mossolov, N Shumeiko, J Suarez Gonzalez, S Alderweireldt, M Bansal, S Bansal, T Cornelis, EA De Wolf, X Janssen, A Knutsson, S Luyckx, L Mucibello, S Ochesanu, B Roland, R Rougny, H Van Haevermaet, P Van Mechelen, N Van Remortel, A Van Spilbeeck, F Blekman, S Blyweert, J D'hondt, A Kalogeropoulos, J Keaveney, M Maes, A Olbrechts, S Tavernier, W Van Doninck, P Van Mulders, GP Van Onsem, I Villella, B Clerbaux, G De Lentdecker, L Favart, APR Gay, T Hreus, A Léonard, PE Marage, A Mohammadi, L Perniè, T Reis, T Seva, L Thomas, C Vander Velde, P Vanlaer, J Wang, V Adler, K Beernaert, L Benucci, A Cimmino, S Costantini, S Dildick, G Garcia, B Klein, J Lellouch, A Marinov, J Mccartin, AA Ocampo Rios, D Ryckbosch, M Sigamani, N Strobbe, F Thyssen, M Tytgat, S Walsh, E Yazgan, N Zaganidis, S Basegmez, C Beluffi, G Bruno

Abstract:

A search for exclusive or quasi-exclusive W+W- production by photon-photon interactions, pp → p(*)W +W-p(*), at √s=7 TeV is reported using data collected by the CMS detector with an integrated luminosity of 5.05 fb-1. Events are selected by requiring a μ ±e∓ vertex with no additional associated charged tracks and dilepton transverse momentum p T(μ ±e∓) > 30 GeV. Two events passing all selection requirements are observed in the data, compared to a standard model expectation of 2.2 ± 0.4 signal events with 0.84 ± 0.15 background. The tail of the dilepton p T distribution is studied for deviations from the standard model. No events are observed with p T > 100 GeV. Model-independent upper limits are computed and compared to predictions involving anomalous quartic gauge couplings. The limits on the parameters α0,CW/λ2 with a dipole form factor and an energy cutoff Λcutoff = 500 GeV are of the order of 10-4. © 2013 CERN for the benefit of the CMS collaboration.
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