Browsing by Author "CMS collaboration (2128 authors)"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
- Measurements of differential and double-differential Drell-Yan cross sections in proton-proton collisions at 8 TeVPublication . CMS collaboration (2128 authors); Hollar, Jonathan; Nayak, Aruna; Bargassa, Pedrame; Beirão Da Cruz E Silva, Cristóvão; Faccioli, Pietro; Ferreira Parracho, Pedro Guilherme; Gallinaro, Michele; Lloret Iglesias, Lara; Nguyen, Federico; Rodrigues Antunes, Joao; Seixas, Joao; Varela, Joao; Vischia, Pietro; David Tinoco Mendes, Andre; Silva, Pedro; Musella, Pasquale; Pela, Joao; Leonardo, NunoMeasurements of the differential and double-differential Drell–Yan cross sections in the dielectron and dimuon channels are presented. They are based on proton–proton collision data at $\sqrt{s} = 8\,\text {TeV} $ recorded with the CMS detector at the LHC and corresponding to an integrated luminosity of 19.7 $\,\text {fb}^{-1}$ . The measured inclusive cross section in the $\mathrm{Z}$ peak region (60–120 $\,\text {GeV}$ ), obtained from the combination of the dielectron and dimuon channels, is $1138 \pm 8\,\text {(exp)} \pm 25\,\text {(theo)} \pm 30\,\text {(lumi)} \text {\,pb} $ , where the statistical uncertainty is negligible. The differential cross section $\mathrm{d}\sigma /\mathrm{d}{}m$ in the dilepton mass range 15–2000 $\,\text {GeV}$ is measured and corrected to the full phase space. The double-differential cross section $\mathrm{d}^2\sigma /\mathrm{d}{}m\,\mathrm{d}|y |$ is also measured over the mass range 20 to 1500 $\,\text {GeV}$ and absolute dilepton rapidity from 0 to 2.4. In addition, the ratios of the normalized differential cross sections measured at $\sqrt{s} = 7$ and 8 $\,\text {TeV}$ are presented. These measurements are compared to the predictions of perturbative QCD at next-to-leading and next-to-next-to-leading (NNLO) orders using various sets of parton distribution functions (PDFs). The results agree with the NNLO theoretical predictions computed with fewz 3.1 using the CT10 NNLO and NNPDF2.1 NNLO PDFs. The measured double-differential cross section and ratio of normalized differential cross sections are sufficiently precise to constrain the proton PDFs.
- Observation of the diphoton decay of the Higgs boson and measurement of its propertiesPublication . CMS collaboration (2128 authors); Hollar, Jonathan; Nayak, Aruna; Bargassa, Pedrame; Beirão Da Cruz E Silva, Cristóvão; Faccioli, Pietro; Ferreira Parracho, Pedro Guilherme; Gallinaro, Michele; Nguyen, Federico; Rodrigues Antunes, Joao; Seixas, Joao; Varela, Joao; Vischia, Pietro; Lloret Iglesias, Lara; David Tinoco Mendes, Andre; Musella, Pasquale; Silva, Pedro; Pela, Joao; Leonardo, NunoObservation of the diphoton decay mode of the recently discovered Higgs boson and measurement of some of its properties are reported. The analysis uses the entire dataset collected by the CMS experiment in proton-proton collisions during the 2011 and 2012 LHC running periods. The data samples correspond to integrated luminosities of 5.1 $\,\text {fb}^\text {-1}$ at $\sqrt{s}=7\,\text {TeV}\,$ and 19.7 $\,\text {fb}^\text {-1}$ at 8 $\,\text {TeV}$ . A clear signal is observed in the diphoton channel at a mass close to 125 $\,\text {GeV}$ with a local significance of $5.7\,\sigma $ , where a significance of $5.2\,\sigma $ is expected for the standard model Higgs boson. The mass is measured to be $124.70\pm 0.34\,\text {GeV} \,=124.70\pm 0.31\,\text {(stat)}\,\pm 0.15\,\text {(syst)}\,\,\text {GeV} \,$ , and the best-fit signal strength relative to the standard model prediction is $1.14^\mathrm{+0.26}_{-0.23}=1.14\pm 0.21\,\text {(stat)}\,^\mathrm{+0.09}_{-0.05}\,\text {(syst)}\,^\mathrm{+0.13}_{-0.09}\,\text {(theo)}\,$ . Additional measurements include the signal strength modifiers associated with different production mechanisms, and hypothesis tests between spin-0 and spin-2 models.