Results are presented from searches for the standard model Higgs boson in proton-proton collisions at root s = 7 and 8 TeV in the Compact Muon Solenoid experiment at the LHC, using data samples corresponding to integrated luminosities of up to 5.1 fb(-1) at 7 TeV and 5.3 fb(-1) at 8 TeV. The search is performed in five decay modes: gamma gamma, ZZ, W+W-, tau(+)tau(-), and b (b) over bar. An excess of events is observed above the expected background, with a local significance of 5.0 standard deviations, at a mass near 125 GeV, signalling the production of a new particle. The expected significance for a standard model Higgs boson of that mass is 5.8 standard deviations. The excess is most significant in the two decay modes with the best mass resolution, gamma gamma and ZZ; a fit to these signals gives a mass of 125.3 +/- 0.4(stat.) +/- 0.5(syst.) GeV. The decay to two photons indicates that the new particle is a boson with spin different from one. (C) 2012 CERN. Published by Elsevier B.V. All rights reserved
Within an effective field theory framework we study heavy-quark--antiquark
systems with a typical distance between the heavy quark and the antiquark
smaller than $1/\Lambda_{\rm QCD}$. A suitable definition of the potential is
given within this framework, while non-potential (retardation) effects are
taken into account in a systematic way. We explore different physical systems.
Model-independent results on the short distance behavior of the energies of the
gluonic excitations between static quarks are obtained. Finally, we show how
infrared renormalons affecting the static potential get cancelled in the
effective theory.Comment: 39 pages, LaTeX, 12 figures. Journal version. Some explanatory
remarks and references adde
This article reviews recent theoretical developments in heavy-quarkonium physics from the point of view of effective-field theories of QCD. We discuss nonrelativistic QCD and concentrate on potential nonrelativistic QCD. The main goal will be to derive Schrödinger equations based on QCD that govern heavy-quarkonium physics in the weak-and strong-coupling regimes. Finally, the review discusses a selected set of applications, which include spectroscopy, inclusive decays, and electromagnetic threshold production.
CONTENTS
We propose an effective field theory for heavy quark-antiquark bound states once the soft gluons have been integrated out. We also give new results for the matching between QCD (QED) and NRQCD (NRQED).
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