Browsing by Author "Österberg, K."

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  • Deile, M.; Aurola, A.; Brücken, E.; Heino, J.; Hilden, T.; Kalliopuska, J.; Kurvinen, K.; Lauhakangas, R.; Lämsä, J.; Oljemark, F.; Ojala, J.; Orava, R.; Österberg, K.; Saarikko, H.; TOTEM Collaboration (2006)
    Springer Proceedings Physics
    At the Tevatron, the total p_bar-p cross-section has been measured by CDF at 546 GeV and 1.8 TeV, and by E710/E811 at 1.8 TeV. The two results at 1.8 TeV disagree by 2.6 standard deviations, introducing big uncertainties into extrapolations to higher energies. At the LHC, the TOTEM collaboration is preparing to resolve the ambiguity by measuring the total p-p cross-section with a precision of about 1 %. Like at the Tevatron experiments, the luminosity-independent method based on the Optical Theorem will be used. The Tevatron experiments have also performed a vast range of studies about soft and hard diffractive events, partly with antiproton tagging by Roman Pots, partly with rapidity gap tagging. At the LHC, the combined CMS/TOTEM experiments will carry out their diffractive programme with an unprecedented rapidity coverage and Roman Pot spectrometers on both sides of the interaction point. The physics menu comprises detailed studies of soft diffractive differential cross-sections, diffractive structure functions, rapidity gap survival and exclusive central production by Double Pomeron Exchange.
  • Antchev, G.; Brucken, E.; Garcia, F.; Heino, J.; Hilden, T.; Kurvinen, Leo Kari-Pekka; Lauhakangas, R.; Mäki, T.; Oljemark, F.; Orava, R.; Österberg, K.; Saarikko, H.; Welti, J.; TOTEM Collaboration (EDP SCIENCES, 2012)
    The TOTEM experiment has measured the charged-particle pseudorapidity density dNch/dη in pp collisions at \sqrt{s} = 7\,{\rm TeV} for 5.3<|η|<6.4 in events with at least one charged particle with transverse momentum above 40 MeV/c in this pseudorapidity range. This extends the analogous measurement performed by the other LHC experiments to the previously unexplored forward η region. The measurement refers to more than 99% of non-diffractive processes and to single and double diffractive processes with diffractive masses above ~3.4 GeV/c2, corresponding to about 95% of the total inelastic cross-section. The dNch/dη has been found to decrease with |η|, from 3.84 ± 0.01(stat) ± 0.37(syst) at |η|=5.375 to 2.38±0.01(stat)±0.21(syst) at |η|=6.375. Several MC generators have been compared to data; none of them has been found to fully describe the measurement.
  • Aaltonen, T.; Mehtala, P.; Orava, R.; Saarikko, H.; Österberg, K.; CDF Collaboration (ELSEVIER BV, 2010)
    We present the result of a search for a massive color-octet vector particle, (e.g. a massive gluon) decaying to a pair of top quarks in proton-antiproton collisions with a center-of-mass energy of 1.96 TeV. This search is based on 1.9 fb$^{-1}$ of data collected using the CDF detector during Run II of the Tevatron at Fermilab. We study $t\bar{t}$ events in the lepton+jets channel with at least one $b$-tagged jet. A massive gluon is characterized by its mass, decay width, and the strength of its coupling to quarks. These parameters are determined according to the observed invariant mass distribution of top quark pairs. We set limits on the massive gluon coupling strength for masses between 400 and 800 GeV$/c^2$ and width-to-mass ratios between 0.05 and 0.50. The coupling strength of the hypothetical massive gluon to quarks is consistent with zero within the explored parameter space.