SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "WFRF:(Johansson V.) "

Sökning: WFRF:(Johansson V.)

Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
41.
  • Aad, G., et al. (författare)
  • Observation of Spin Correlation in t(t)over-bar Events from pp Collisions at root s=7 TeV Using the ATLAS Detector
  • 2012
  • Ingår i: Physical Review Letters. - American Physical Society. - 1079-7114. ; 108:21
  • Tidskriftsartikel (refereegranskat)abstract
    • A measurement of spin correlation in t (t) over bar production is reported using data collected with the ATLAS detector at the LHC, corresponding to an integrated luminosity of 2.1 fb(-1). Candidate events are selected in the dilepton topology with large missing transverse energy and at least two jets. The difference in azimuthal angle between the two charged leptons in the laboratory frame is used to extract the correlation between the top and antitop quark spins. In the helicity basis the measured degree of correlation corresponds to A(helicity) = 0.40(-0.08)(+0.09), in agreement with the next-to-leading-order standard model prediction. The hypothesis of zero spin correlation is excluded at 5.1 standard deviations.
42.
  • Aad, G., et al. (författare)
  • Performance of jet substructure techniques for large-R jets in proton-proton collisions at root s=7 TeV using the ATLAS detector
  • 2013
  • Ingår i: Journal of High Energy Physics. - Springer. - 1029-8479. ; :9
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper presents the application of a variety of techniques to study jet substructure. The performance of various modified jet algorithms, or jet grooming techniques, for several jet types and event topologies is investigated for jets with transverse momentum larger than 300 GeV. Properties of jets subjected to the mass-drop filtering, trimming, and pruning algorithms are found to have a reduced sensitivity to multiple proton-proton interactions, are more stable at high luminosity and improve the physics potential of searches for heavy boosted objects. Studies of the expected discrimination power of jet mass and jet substructure observables in searches for new physics are also presented. Event samples enriched in boosted W and Z bosons and top-quark pairs are used to study both the individual jet invariant mass scales and the efficacy of algorithms to tag boosted hadronic objects. The analyses presented use the full 2011 ATLAS dataset, corresponding to an integrated luminosity of 4.7 +/- 0.1 fb(-1) from proton-proton collisions produced by the Large Hadron Collider at a centre-of-mass energy of root s = 7 TeV.
43.
  • Aad, G., et al. (författare)
  • Search for a multi-Higgs-boson cascade in W(+)W(-)b(b)over-bar events with the ATLAS detector in pp collisions at root s=8 TeV
  • 2014
  • Ingår i: Physical Review D (Particles, Fields, Gravitation and Cosmology). - American Physical Society. - 1550-2368. ; 89:3
  • Tidskriftsartikel (refereegranskat)abstract
    • A search is presented for new particles in an extension to the Standard Model that includes a heavy Higgs boson (H-0), an intermediate charged Higgs-boson pair (H-+/-), and a light Higgs boson (h(0)). The analysis searches for events involving the production of a single heavy neutral Higgs boson which decays to the charged Higgs boson and a W boson, where the charged Higgs boson subsequently decays into a W boson and the lightest neutral Higgs boson decaying to a bottom-antibottom-quark pair. Such a cascade results in a W-boson pair and a bottom-antibottom-quark pair in the final state. Events with exactly one lepton, missing transverse momentum, and at least four jets are selected from a data sample corresponding to an integrated luminosity of 20.3 fb(-1), collected by the ATLAS detector in proton-proton collisions at root s = 8 TeV at the LHC. The data are found to be consistent with Standard Model predictions, and 95% confidence-level upper limits are set on the product of cross section and branching ratio. These limits range from 0.065 to 43 pb as a function of H-0 and H-+/- masses, with m(h)o fixed at 125 GeV.
44.
  • Aad, G., et al. (författare)
  • Search for charginos nearly mass degenerate with the lightest neutralino based on a disappearing-track signature in pp collisions at root(s)=8 TeV with the ATLAS detector
  • 2013
  • Ingår i: Physical Review D (Particles, Fields, Gravitation and Cosmology). - American Physical Society. - 1550-2368. ; 88:11
  • Tidskriftsartikel (refereegranskat)abstract
    • A search is presented for direct chargino production based on a disappearing-track signature using 20.3 fb(-1) of proton-proton collisions at root s = 8 TeV collected with the ATLAS experiment at the LHC. In anomaly-mediated supersymmetry breaking (AMSB) models, the lightest chargino is nearly mass degenerate with the lightest neutralino and its lifetime is long enough to be detected in the tracking detectors by identifying decays that result in tracks with no associated hits in the outer region of the tracking system. Some models with supersymmetry also predict charginos with a significant lifetime. This analysis attains sensitivity for charginos with a lifetime between 0.1 and 10 ns, and significantly surpasses the reach of the LEP experiments. No significant excess above the background expectation is observed for candidate tracks with large transverse momentum, and constraints on chargino properties are obtained. In the AMSB scenarios, a chargino mass below 270 GeV is excluded at 95% confidence level.
45.
  • Aad, G., et al. (författare)
  • Search for Dark Matter in Events with a Hadronically Decaying W or Z Boson and Missing Transverse Momentum in pp Collisions at root s=8 TeV with the ATLAS Detector
  • 2014
  • Ingår i: Physical Review Letters. - American Physical Society. - 1079-7114. ; 112:4
  • Tidskriftsartikel (refereegranskat)abstract
    • A search is presented for dark matter pair production in association with a W or Z boson in pp collisions representing 20.3 fb(-1) of integrated luminosity at root s = 8 TeV using data recorded with the ATLAS detector at the Large Hadron Collider. Events with a hadronic jet with the jet mass consistent with a W or Z boson, and with large missing transverse momentum are analyzed. The data are consistent with the standard model expectations. Limits are set on the mass scale in effective field theories that describe the interaction of dark matter and standard model particles, and on the cross section of Higgs production and decay to invisible particles. In addition, cross section limits on the anomalous production of W or Z bosons with large missing transverse momentum are set in two fiducial regions.
46.
  • Aad, G., et al. (författare)
  • Search for dark matter in events with a Z boson and missing transverse momentum in pp collisions at root s=8 TeV with the ATLAS detector
  • 2014
  • Ingår i: Physical Review D (Particles, Fields, Gravitation and Cosmology). - American Physical Society. - 1550-2368. ; 90:1
  • Tidskriftsartikel (refereegranskat)abstract
    • A search is presented for production of dark-matter particles recoiling against a leptonically decaying Z boson in 20.3 fb(-1) of pp collisions at root s = 8 TeV with the ATLAS detector at the Large Hadron Collider. Events with large missing transverse momentum and two oppositely charged electrons or muons consistent with the decay of a Z boson are analyzed. No excess above the Standard Model prediction is observed. Limits are set on the mass scale of the contact interaction as a function of the dark-matter particle mass using an effective field theory description of the interaction of dark matter with quarks or with Z bosons. Limits are also set on the coupling and mediator mass of a model in which the interaction is mediated by a scalar particle.
47.
  • Aad, G., et al. (författare)
  • Search for direct third-generation squark pair production in final states with missing transverse momentum and two b-jets in root s=8 TeV pp collisions with the ATLAS detector
  • 2013
  • Ingår i: Journal of High Energy Physics. - Springer. - 1029-8479. ; :10
  • Tidskriftsartikel (refereegranskat)abstract
    • The results of a search for pair production of supersymmetric partners of the Standard Model third-generation quarks are reported. This search uses 20.1 fb(-1) of pp collisions at root s = 8 TeV collected by the ATLAS experiment at the Large Hadron Collider. The lightest bottom and top squarks ((b) over tilde (1) and (t) over tilde (1) respectively) are searched for in a final state with large missing transverse momentum and two jets identified as originating from b-quarks. No excess of events above the expected level of Standard Model background is found. The results are used to set upper limits on the visible cross section for processes beyond the Standard Model. Exclusion limits at the 95% confidence level on the masses of the third-generation squarks are derived in phenomenological supersymmetric R-parity-conserving models in which either the bottom or the top squark is the lightest squark. The (b) over tilde (1) is assumed to decay via (b) over tilde (1) -> b (chi) over tilde (0)(1) and the (t) over tilde (1) via (t) over tilde (1) b (chi) over tilde (+/-)(1), with undetectable products of the subsequent decay of the (chi) over tilde (+/-)(1) due to the small mass splitting between the (chi) over tilde (+/-)(1) and the (chi) over tilde (0)(1)
48.
  • Aad, G., et al. (författare)
  • Search for direct top-squark pair production in final states with two leptons in pp collisions at root s=8 TeV with the ATLAS detector
  • 2014
  • Ingår i: Journal of High Energy Physics. - Springer. - 1029-8479. ; :6
  • Tidskriftsartikel (refereegranskat)abstract
    • A search is presented for direct top-squark pair production in final states with two leptons (electrons or muons) of opposite charge using 20.3 fb(-1) of pp collision data at root s = 8 TeV, collected by the ATLAS experiment at the Large Hadron Collider in 2012. No excess over the Standard Model expectation is found. The results are interpreted under the separate assumptions (i) that the top squark decays to a b-quark in addition to an on-shell chargino whose decay occurs via a real or virtual W boson, or (ii) that the top squark decays to a t-quark and the lightest neutralino. A top squark with a mass between 150 GeV and 445 GeV decaying to a b-quark and an on-shell chargino is excluded at 95% confidence level for a top squark mass equal to the chargino mass plus 10 GeV, in the case of a 1 GeV lightest neutralino. Top squarks with masses between 215 (90) GeV and 530 (170) GeV decaying to an on-shell (off-shell) t-quark and a neutralino are excluded at 95% confidence level for a 1 GeV neutralino.
49.
  • Aad, G., et al. (författare)
  • Search for events with large missing transverse momentum, jets, and at least two tau leptons in 7 TeV proton-proton collision data with the ATLAS detector ATLAS Collaboration
  • 2012
  • Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - Elsevier. - 0370-2693. ; 714:2-5, s. 180-196
  • Tidskriftsartikel (refereegranskat)abstract
    • A search for events with large missing transverse momentum, jets, and at least two tau leptons has been performed using 2 fb(-1) of proton-proton collision data at root s = 7 TeV recorded with the ATLAS detector at the Large Hadron Collider. No excess above the Standard Model background expectation is observed and a 95% CL upper limit on the visible cross section for new phenomena is set, where the visible cross section is defined by the product of cross section, branching fraction, detector acceptance and event selection efficiency. A 95% CL lower limit of 32 TeV is set on the gauge-mediated supersymmetry breaking (GMSB) scale Lambda independent of tan beta. These limits provide the most stringent tests to date in a large part of the considered parameter space. Published by Elsevier B.V.
  •  
50.
  • Aad, G., et al. (författare)
  • Search for excited electrons and muons in root s=8 TeV proton-proton collisions with the ATLAS detector
  • 2013
  • Ingår i: New Journal of Physics. - IOP Publishing. - 1367-2630. ; 15
  • Tidskriftsartikel (refereegranskat)abstract
    • The ATLAS detector at the Large Hadron Collider is used to search for excited electrons and excited muons in the channel pp -> ll* -> ll gamma, assuming that excited leptons are produced via contact interactions. The analysis is based on 13 fb(-1) of pp collisions at a centre-of-mass energy of 8 TeV. No evidence for excited leptons is found, and a limit is set at the 95% credibility level on the cross section times branching ratio as a function of the excited-lepton mass m(l*). For m(l*) >= 0.8 TeV, the respective upper limits on sigma B(l(*) -> l gamma) are 0.75 and 0.90 fb for the e* and mu* searches. Limits on sigma B are converted into lower bounds on the compositeness scale 3. In the special case where Lambda = m(l*), excited-electron and excited-muon masses below 2.2 TeV are excluded.
Skapa referenser, mejla, bekava och länka
Åtkomst
fritt online (625)
Typ av publikation
tidskriftsartikel (1738)
konferensbidrag (225)
annan publikation (24)
forskningsöversikt (19)
bokkapitel (18)
rapport (12)
visa fler...
doktorsavhandling (3)
bok (2)
samlingsverk (redaktörskap) (1)
proceedings (redaktörskap) (1)
patent (1)
visa färre...
Typ av innehåll
refereegranskat (1909)
övrigt vetenskapligt (156)
populärvet., debatt m.m. (5)
Författare/redaktör
Andreazza, A. (451)
Abdallah, J, (449)
Anjos, N. (443)
Baroncelli, A. (441)
Asman, B. (435)
Allport, P. P. (405)
visa fler...
Åsman, Barbro, (398)
Bai, Y. (395)
Moa, Torbjörn, (383)
Baker, O. K. (380)
Aleksa, M. (379)
Arabidze, G. (379)
Adye, T. (378)
Anghinolfi, F. (378)
Jon-And, Kerstin, (377)
Antonaki, A. (377)
Bates, R. L. (377)
Antonelli, M. (376)
Bohm, Christian, (375)
Sjölin, Jörgen, (375)
Gellerstedt, Karl, (375)
Eriksson, Daniel, (375)
Asquith, L. (375)
Banas, E. (375)
Barklow, T. (375)
Barr, A. J. (375)
Clement, Christophe, (374)
Hellman, Sten, (374)
Artamonov, A., (374)
Abi, B. (374)
Abramowicz, H. (374)
Adelman, J. (374)
Akimov, A. V. (374)
Aleksandrov, I. N. (374)
Alexandre, G. (374)
Alhroob, M. (374)
Amelung, C. (374)
Anastopoulos, C. (374)
Arai, Y. (374)
Arnaez, O. (374)
Assamagan, K. (374)
Azuma, Y. (374)
Baak, M. A. (374)
Bachacou, H. (374)
Bachas, K. (374)
Backes, M. (374)
Barisonzi, M. (374)
Barlow, N. (374)
Batley, J. R. (374)
Beau, T. (374)
visa färre...
Lärosäte
Uppsala universitet (947)
Kungliga Tekniska Högskolan (720)
Lunds universitet (685)
Stockholms universitet (492)
Karolinska Institutet (262)
Göteborgs universitet (193)
visa fler...
Umeå universitet (137)
Chalmers tekniska högskola (130)
Linköpings universitet (41)
Linnéuniversitetet (41)
Örebro universitet (19)
RISE (12)
Högskolan i Jönköping (10)
Högskolan Dalarna (9)
Södertörns högskola (8)
Mittuniversitetet (5)
Luleå tekniska universitet (3)
Mälardalens högskola (3)
Högskolan i Gävle (3)
Naturhistoriska riksmuseet (3)
Högskolan Kristianstad (2)
Malmö universitet (2)
Högskolan i Skövde (2)
Högskolan i Borås (2)
Blekinge Tekniska Högskola (1)
VTI - Statens väg- och transportforskningsinstitut (1)
visa färre...
Språk
Engelska (1999)
Svenska (9)
Odefinierat språk (7)
Forskningsämne (UKÄ/SCB)
Naturvetenskap (1144)
Medicin och hälsovetenskap (392)
Teknik (276)
Samhällsvetenskap (30)
Lantbruksvetenskap (2)
Humaniora (2)

År

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy