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An additional study of multi-muon events produced in pp@? collisions at s=1.96 TeV
CDF Collaboration,Aaltonen, T.,Alvarez Gonzalez, B.,Amerio, S.,Amidei, D.,Anastassov, A.,Annovi, A.,Antos, J.,Apollinari, G.,Apresyan, A.,Arisawa, T.,Artikov, A.,Ashmanskas, W.,Auerbach, B.,Azfar, F. North-Holland Pub. Co 2012 Physics letters: B Vol.710 No.2
We present one additional study of multi-muon events produced at the Fermilab Tevatron collider and recorded by the CDF II detector. We use a data set acquired with a dedicated dimuon trigger and corresponding to an integrated luminosity of 3.9 fb<SUP>-1</SUP>. We investigate the distribution of the azimuthal angle between the two trigger muons in events containing at least four additional muon candidates to test the compatibility of these events with originating from known QCD processes. We find that this distribution is markedly different from what is expected from such QCD processes and this observation strongly disfavors the possibility that multi-muon events result from an underestimate of the rate of misidentified muons in ordinary QCD events.
Search for new color-octet vector particle decaying to tt¯ in pp¯ collisions at s=1.96 TeV
Aaltonen, T.,Adelman, J.,Á,lvarez Gonzá,lez, B.,Amerio, S.,Amidei, D.,Anastassov, A.,Annovi, A.,Antos, J.,Apollinari, G.,Apresyan, A.,Arisawa, T.,Artikov, A.,Asaadi, J.,Ashmanskas, W.,Atta Elsevier 2010 Physics letters: B Vol.691 No.4
<P><B>Abstract</B></P><P>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<SUP> fb−1</SUP> of data collected using the CDF detector during Run II of the Tevatron at Fermilab. We study tt¯ events in the lepton+jets channel with at least one <I>b</I>-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/<SUP>c2</SUP> 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.</P>
Search for Long-Lived Massive Charged Particles in 1.96 TeVpp¯Collisions
Aaltonen, T.,Adelman, J.,Akimoto, T.,Á,lvarez Gonzá,lez, B.,Amerio, S.,Amidei, D.,Anastassov, A.,Annovi, A.,Antos, J.,Apollinari, G.,Apresyan, A.,Arisawa, T.,Artikov, A.,Ashmanskas, W.,Att American Physical Society 2009 Physical Review Letters Vol.103 No.2
<P>We performed a signature-based search for long-lived charged massive particles produced in 1.0 fb-1 of pp[over ] collisions at sqrt[s]=1.96 TeV, collected with the CDF II detector using a high transverse-momentum (pT) muon trigger. The search used time of flight to isolate slowly moving, high-pT particles. One event passed our selection cuts with an expected background of 1.9+/-0.2 events. We set an upper bound on the production cross section and, interpreting this result within the context of a stable scalar top-quark model, set a lower limit on the particle mass of 249 GeV/c2 at 95% C.L.</P>
Observation of Exclusive Charmonium Production andγγ→μ+μ−inpp¯Collisions ats=1.96 TeV
Aaltonen, T.,Adelman, J.,Akimoto, T.,Albrow, M. G.,Á,lvarez Gonzá,lez, B.,Amerio, S.,Amidei, D.,Anastassov, A.,Annovi, A.,Antos, J.,Apollinari, G.,Apresyan, A.,Arisawa, T.,Artikov, A.,Ashm American Physical Society 2009 Physical Review Letters Vol.102 No.24
<P>In CDF we have observed the reactions p + p[over] --> p + X + p[over], with X being a centrally produced J/psi, psi(2S), or chi_{c0}, and gammagamma-->micro;{+}micro;{-} in pp[over] collisions at sqrt[s] = 1.96 TeV. The event signature requires two oppositely charged central muons, and either no other particles or one additional photon detected. Exclusive vector meson production is as expected for elastic photoproduction, gamma + p --> J/psi(psi(2S)) + p, observed here for the first time in hadron-hadron collisions. We also observe exclusive chi_{c0} --> J/psi + gamma. The cross sections dsigma/dy|_{y = 0} for J/psi, psi(2S), and chi_{c0} are 3.92 +/- 0.25(stat) +/- 0.52(syst) nb, 0.53 +/- 0.09(stat) +/- 0.10(syst) nb, and 76 +/- 10(stat) +/- 10(syst) nb, respectively, and the continuum is consistent with QED. We put an upper limit on the cross section for Odderon exchange in exclusive J/psi production.</P>
Inclusive Search for Squark and Gluino Production inpp¯Collisions ats=1.96 TeV
Aaltonen, T.,Adelman, J.,Akimoto, T.,Albrow, M. G.,Gonzá,lez, B. Á,lvarez,Amerio, S.,Amidei, D.,Anastassov, A.,Annovi, A.,Antos, J.,Apollinari, G.,Apresyan, A.,Arisawa, T.,Artikov, A.,Ashm American Physical Society 2009 Physical Review Letters Vol.102 No.12
<P>We report on a search for inclusive production of squarks and gluinos in pp[over ] collisions at sqrt[s]=1.96 TeV, in events with large missing transverse energy and multiple jets of hadrons in the final state. The study uses a CDF Run II data sample corresponding to 2 fb(-1) of integrated luminosity. The data are in good agreement with the standard model predictions, giving no evidence for any squark or gluino component. In an R-parity conserving minimal supergravity scenario with A(0)=0, mu<0, and tanbeta=5, 95% C.L. upper limits on the production cross sections in the range between 0.1 and 1 pb are obtained, depending on the squark and gluino masses considered. For gluino masses below 280 GeV/c(2), arbitrarily large squark masses are excluded at the 95% C.L., while for mass degenerate gluinos and squarks, masses below 392 GeV/c(2) are excluded at the 95% C.L.</P>
Search for narrow resonances lighter than ϒ mesons
Aaltonen, T.,Adelman, J.,Akimoto, T.,Á,lvarez Gonzá,lez, B.,Amerio, S.,Amidei, D.,Anastassov, A.,Annovi, A.,Antos, J.,Apollinari, G.,Apresyan, A.,Arisawa, T.,Artikov, A.,Ashmanskas, W.,Att Springer-Verlag 2009 European Physical Journal C Vol.62 No.2
Search forR-Parity Violating Decays of Sneutrinos toeμ,μτ, andeτPairs inpp¯Collisions ats=1.96 TeV
Aaltonen, T.,Adelman, J.,Á,lvarez Gonzá,lez, B.,Amerio, S.,Amidei, D.,Anastassov, A.,Annovi, A.,Antos, J.,Apollinari, G.,Appel, J.,Apresyan, A.,Arisawa, T.,Artikov, A.,Asaadi, J.,Ashmanska American Physical Society 2010 Physical Review Letters Vol.105 No.19
<P>We present a search for supersymmetric neutrino 관[over ?] production using the Tevatron pp[over ¯] collision data collected with the CDF II detector and corresponding to an integrated luminosity of 1??fb^{-1}. We focus on the scenarios predicted by the R-parity violating (RPV) supersymmetric models in which sneutrinos decay to two charged leptons of different flavor. With the data consistent with the standard model expectations, we set upper limits on ?(pp[over ¯]??over ?])×BR(관[over ?]?관,관?,e?) and use these results to constrain the RPV couplings as a function of the sneutrino mass.</P>
Search for new particles decaying into dijets in proton-antiproton collisions ats=1.96 TeV
Aaltonen, T.,Adelman, J.,Akimoto, T.,Á,lvarez Gonzá,lez, B.,Amerio, S.,Amidei, D.,Anastassov, A.,Annovi, A.,Antos, J.,Apollinari, G.,Apresyan, A.,Arisawa, T.,Artikov, A.,Ashmanskas, W.,Att American Physical Society 2009 PHYSICAL REVIEW D - Vol.79 No.11