Measurement of diffraction dissociation cross sections in pp collisions at s\sqrt{s} = 7 TeV

Measurements of diffractive dissociation cross sections in pp collisions at s√=7  TeV are presented in kinematic regions defined by the masses MX and MY of the two final-state hadronic systems separated by the largest rapidity gap in the event. Differential cross sections are measured as a function of ξX=M2X/s in the region −5.53, log10MX>1.1, and log10MY>1.1, a region dominated by DD. The cross sections integrated over these regions are found to be, respectively, 2.99±0.02(stat)+0.32−0.29(syst)  mb, 1.18±0.02(stat)±0.13(syst)  mb, and 0.58±0.01(stat)+0.13−0.11(syst)  mb, and are used to extract extrapolated total SD and DD cross sections. In addition, the inclusive differential cross section, dσ/dΔηF, for events with a pseudorapidity gap adjacent to the edge of the detector, is measured over ΔηF=8.4 units of pseudorapidity. The results are compared to those of other experiments and to theoretical predictions and found compatible with slowly rising diffractive cross sections as a function of center-of-mass energy

Search for a pseudoscalar boson decaying into a ZZ boson and the 125 GeV Higgs boson in ℓ+ℓ−bbˉb\bar{b} final states

Results are reported on a search for decays of a pseudoscalar A boson into a $Z$ boson and a light scalar h boson, where the Z boson decays into a pair of oppositely-charged electrons or muons, and the h boson decays into $b\bar{b}$. The search is based on data from proton–proton collisions at a center-of-mass energy $\sqrt{s}$=8 TeV collected with the CMS detector, corresponding to an integrated luminosity of 19.7 $fb^{−1}$ . The h boson is assumed to be the standard model-like Higgs boson with a mass of 125 GeV. With no evidence for signal, upper limits are obtained on the product of the production cross section and the branching fraction of the A boson in the Zh channel. Results are also interpreted in the context of two Higgs doublet models

Constraints on the χ_(c1) versus χ_(c2) polarizations in proton-proton collisions at √s = 8 TeV

The polarizations of promptly produced χ_(c1) and χ_(c2) mesons are studied using data collected by the CMS experiment at the LHC, in proton-proton collisions at √s=8  TeV. The χ_c states are reconstructed via their radiative decays χ_c → J/ψγ, with the photons being measured through conversions to e⁺e⁻, which allows the two states to be well resolved. The polarizations are measured in the helicity frame, through the analysis of the χ_(c2) to χ_(c1) yield ratio as a function of the polar or azimuthal angle of the positive muon emitted in the J/ψ → μ⁺μ⁻ decay, in three bins of J/ψ transverse momentum. While no differences are seen between the two states in terms of azimuthal decay angle distributions, they are observed to have significantly different polar anisotropies. The measurement favors a scenario where at least one of the two states is strongly polarized along the helicity quantization axis, in agreement with nonrelativistic quantum chromodynamics predictions. This is the first measurement of significantly polarized quarkonia produced at high transverse momentum