Long-range and short-range dihadron angular correlations in central PbPb collisions at √sNN=2.76 TeV

This is the pre-print version of the Published Article, which can be accessed from the link below.First measurements of dihadron correlations for charged particles are presented for central PbPb collisions at a nucleon-nucleon center-of-mass energy of 2.76TeV over a broad range in relative pseudorapidity ( ) and the full range of relative azimuthal angle ( ). The data were collected with the CMS detector, at the LHC. A broadening of the away-side ( ) azimuthal correlation is observed at all , as compared to the measurements in pp collisions. Furthermore, long-range dihadron correlations in are observed for particles with similar values. This phenomenon, also known as the \ridge", persists up to at least j j = 4. For particles with transverse momenta (pT) of 2-4 GeV/c, the ridge is found to be most prominent when these particles are correlated with particles of pT = 2-6 GeV/c, and to be much reduced when paired with particles of pT = 10-12 GeV/c

Suppression of non-prompt J/psi, prompt J/psi, and Upsilon(1S) in PbPb collisions at root s(NN)=2.76 TeV

Yields of prompt and non-prompt J/ψ, as well as Y(1S) mesons, are measured by the CMS experiment via their μ +μ - decays in PbPb and pp collisions at √/s NN = 2.76 TeV for quarkonium rapidity |y| < 2.4. Differential cross sections and nuclear modification factors are reported as functions of y and transverse momentum pT, as well as collision centrality. For prompt J/ψ with relatively high pT (6.5 < pT < 30 GeV/c), a strong, centrality-dependent suppression is observed in PbPb collisions, compared to the yield in pp collisions scaled by the number of inelastic nucleon-nucleon collisions. In the same kinematic range, a suppression of non-prompt J/ψ, which is sensitive to the in-medium b-quark energy loss, is measured for the first time. Also the low-pT Y(1S) mesons are suppressed in PbPb collisions. © CERN

Search for the standard model Higgs boson in the H -&gt; ZZ -&gt; l(+)l(-)tau(+)tau(-) decay channel in pp collisions at root s=7 TeV

A search is reported for the standard model Higgs boson in the H → ZZ → l +l -τ +τ - decay mode, where l = μ or e, in proton-proton collisions at □s = 7TeV, corresponding to an integrated luminosity of 4.7 fb-1 collected with the CMS detector at the LHC. No evidence is found for a significant deviation from the background expectation. An upper limit four to twelve times larger than the predicted value is set at 95% confidence level for the product of the standard model Higgs boson production cross section and decay branching fraction in the mass range 190 &lt; mH &lt; 600 GeV. © 2012 SISSA