119116907
Studies of jet mass in dijet and W/Z + jet events
A bstract
 Invariant mass spectra for jets reconstructed using the anti-kT and CambridgeAachen algorithms are studied for different jet “grooming” techniques in data corresponding to an integrated luminosity of 5 fb−1, recorded with the CMS detector in proton-proton collisions at the LHC at a center-of-mass energy of 7 TeV. Leading-order QCD predictions for inclusive dijet and W/Z+jet production combined with parton-shower Monte Carlo models are found to agree overall with the data, and the agreement improves with the implementation of jet grooming methods used to distinguish merged jets of large transverse momentum from softer QCD gluon radiation.
841502
Observation of the diphoton decay of the Higgs boson and measurement of its properties
Observation 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$$\,\text {fb}^\text {-1}$$fb-1at $$\sqrt{s}=7\,\text {TeV}\,$$s=7TeV and 19.7$$\,\text {fb}^\text {-1}$$fb-1at 8$$\,\text {TeV}$$TeV . A clear signal is observed in the diphoton channel at a mass close to 125$$\,\text {GeV}$$GeV with a local significance of $$5.7\,\sigma $$5.7σ, where a significance of $$5.2\,\sigma $$5.2σ is expected for the standard model Higgs boson. The mass is measured to be $$124.70\pm 0.34\,\text {GeV} \,=124.70\pm 0.31\,\text {(stat)}\,\pm 0.15\,\text {(syst)}\,\,\text {GeV} \,$$124.70±0.34GeV=124.70±0.31(stat)±0.15(syst)GeV , and the best-fit signal strength relative to the standard model prediction is $$1.14^\mathrm{+0.26}_{-0.23}=1.14\pm 0.21\,\text {(stat)}\,$$1.14-0.23+0.26=1.14±0.21(stat)$$^\mathrm{+0.09}_{-0.05}\,\text {(syst)}\,$$-0.05+0.09(syst)$$^\mathrm{+0.13}_{-0.09}\,\text {(theo)}\,$$-0.09+0.13(theo). Additional measurements include the signal strength modifiers associated with different production mechanisms, and hypothesis tests between spin-0 and spin-2 models.
37672579
Search for heavy neutrinos and $$\mathrm {W}$$W bosons with right-handed couplings in proton–proton collisions at $$\sqrt{s} = 8\,\text {TeV} $$s=8TeV
A search for heavy, right-handed neutrinos, $$\mathrm {N}_{\ell }$$Nℓ ($$\ell = \mathrm {e}, \mu $$ℓ=e,μ), and right-handed $$\mathrm {W}_{\mathrm {R}}$$WR bosons, which arise in the left-right symmetric extensions of the standard model, has been performed by the CMS experiment. The search was based on a sample of two lepton plus two jet events collected in proton–proton collisions at a center-of-mass energy of 8$$\,\text {TeV}$$TeV corresponding to an integrated luminosity of 19.7 $$\mathrm{fb}^{-1}$$fb-1. For models with strict left-right symmetry, and assuming only one $$\mathrm {N}_{\ell }$$Nℓ flavor contributes significantly to the $$\mathrm {W}_{\mathrm {R}}$$WR decay width, the region in the two-dimensional $$(M_{\mathrm {W}_{\mathrm {R}}}, M_{\mathrm {N}_{\ell }})$$(MWR,MNℓ) mass plane excluded at a 95 % confidence level extends to approximately $$M_{\mathrm {W}_{\mathrm {R}}} = 3.0\,\text {TeV} $$MWR=3.0TeV and covers a large range of neutrino masses below the $$\mathrm {W}_{\mathrm {R}}$$WR boson mass, depending on the value of $$M_{\mathrm {W}_{\mathrm {R}}}$$MWR. This search significantly extends the $$(M_{\mathrm {W}_{\mathrm {R}}}, M_{\mathrm {N}_{\ell }})$$(MWR,MNℓ) exclusion region beyond previous results.
32172622
Measurement of WZ and ZZ production in pp collisions at $$\sqrt{s} = 8\,\text {TeV} $$s=8TeV in final states with b-tagged jets
Measurements are reported of the WZ and ZZ production cross sections in proton-proton collisions at $$\sqrt{s} = 8$$s=8$$\,\text {TeV}$$TeV in final states where one Z boson decays to b-tagged jets. The other gauge boson, either W or Z, is detected through its leptonic decay (either $$\mathrm {W}\rightarrow \mathrm {e}\nu $$W→eν, $$\mathrm {\mu }\nu $$μν or $$\mathrm {Z}\rightarrow \mathrm {e}^+\mathrm {e}^-$$Z→e+e-, $$\mathrm {\mu ^+}\mathrm {\mu ^-}$$μ+μ-, or $${\nu }\overline{\nu }$$νν¯). The results are based on data corresponding to an integrated luminosity of 18.9 fb$$^{-1}$$-1 collected with the CMS detector at the Large Hadron Collider. The measured cross sections, $$\sigma (\mathrm {p}\mathrm {p}\rightarrow \mathrm {W}\mathrm {Z}) = 30.7 \pm 9.3\,\text {(stat.)} \pm 7.1\,\text {(syst.)} \pm 4.1\,\text {(th.)} \pm 1.0\,\text {(lum.)} \,\text {pb} $$σ(pp→WZ)=30.7±9.3(stat.)±7.1(syst.)±4.1(th.)±1.0(lum.)pb and $$\sigma (\mathrm {p}\mathrm {p}\rightarrow \mathrm {Z}\mathrm {Z}) = 6.5 \pm 1.7\,\text {(stat.)} \pm 1.0\,\text {(syst.)} \pm 0.9\,\text {(th.)} \pm 0.2\,\text {(lum.)} \,\text {pb} $$σ(pp→ZZ)=6.5±1.7(stat.)±1.0(syst.)±0.9(th.)±0.2(lum.)pb, are consistent with next-to-leading order quantum chromodynamics calculations.
86624438
Search for massive resonances decaying into pairs of boosted bosons in semi-leptonic final states at s$$ \sqrt{s} $$ = 8 TeV
A bstractA search for new resonances decaying to WW, ZZ, or WZ is presented. Final states are considered in which one of the vector bosons decays leptonically and the other hadronically. Results are based on data corresponding to an integrated luminosity of 19.7 fb−1 recorded in proton-proton collisions at s$$ \sqrt{s} $$ = 8 TeV with the CMS detector at the CERN LHC. Techniques aiming at identifying jet substructures are used to analyze signal events in which the hadronization products from the decay of highly boosted W or Z bosons are contained within a single reconstructed jet. Upper limits on the production of generic WW, ZZ, or WZ resonances are set as a function of the resonance mass and width. We increase the sensitivity of the analysis by statistically combining the results of this search with a complementary study of the all-hadronic final state. Upper limits at 95% confidence level are set on the bulk graviton production cross section in the range from 700 to 10 fb for resonance masses between 600 and 2500 GeV, respectively. These limits on the bulk graviton model are the most stringent to date in the diboson final state.

1321352
Search for new physics with same-sign isolated dilepton events with jets and missing transverse energy.
A search for new physics is performed in events with two same-sign isolated leptons, hadronic jets, and missing transverse energy in the final state. The analysis is based on a data sample corresponding to an integrated luminosity of 4.98 fb(-1) produced in pp collisions at a center-of-mass energy of 7 TeV collected by the CMS experiment at the LHC. This constitutes a factor of 140 increase in integrated luminosity over previously published results. The observed yields agree with the standard model predictions and thus no evidence for new physics is found. The observations are used to set upper limits on possible new physics contributions and to constrain supersymmetric models. To facilitate the interpretation of the data in a broader range of new physics scenarios, information on the event selection, detector response, and efficiencies is provided.
111355896
GROUND VIBRATION MEASUREMENT AT NSRRC SITE
For the future TPS project in the NSRRC, ground vibration would be important for this new machine. We have monitored the ground vibration under various experimental conditions at NSRRC site. Sensors were installed in different sites, on the ground and underground in different depth up to 40 meters. From the collected data, we compare the effect of day and night, traffic effect, and internal machine vibration. Specific vibration sources and their propagations are also discussed.
201238536
Measurements of spin correlation in top-antitop quark events from proton-proton collisions at √s =7 TeV using the ATLAS detector
Measurements of spin correlation in top quark pair production are presented using data collected with the ATLAS detector at the LHC with proton-proton collisions at a center-of-mass energy of 7 TeV, corresponding to an integrated luminosity of 4.6 fb(-1). Events are selected in final states with two charged leptons and at least two jets and in final states with one charged lepton and at least four jets. Four different observables sensitive to different properties of the top quark pair production mechanism are used to extract the correlation between the top and antitop quark spins. Some of these observables are measured for the first time. The measurements are in good agreement with the Standard Model prediction at next-to-leading-order accuracy.
123363108
A realistic design of the CBM-TOF wall based on modules commissioned in-beam
The Compressed Baryonic Matter experiment at the future Facility for Antiproton and Ion Research will use a time-of-flight (TOF) wall for hadron identification, which is at the moment planned to be based on the Multi-gap Resistive Plate Chamber (MRPC) technology. The wall will be placed at 10m distance from the target, covering an area of the order of 150 m2. Over such an area, it will provide a time-of-flight resolution of 80 ps, by resorting to ca. 50000 RPC cells (in multi-strip or multi-pad configuration). Fluxes of quasi-minimum ionizing particles (γβ≥3) as high as 20 kHz/cm2 can be reached in the central region, corresponding to the low polar angle/high rapidity section. We propose here a realistic design for building the TOF wall by resorting to a single technology based on low-resistivity doped glass and relying on small structural modifications of the modules developed and tested during the last two years. Latest results from the modules are summarized. A comprehensive analytic discussion on the counter performance under non-uniform beams, when neglecting non-local effects, is also presented.
120805024
Search for First Generation Scalar Leptoquarks in pp Collisions at $\sqrt{s}=7$ TeV with the ATLAS Detector
We report a search for first generation scalar leptoquarks using 1.03 fb−1 of proton–proton collisions data produced by the Large Hadron Collider at and recorded by the ATLAS experiment. Leptoquarks are sought via their decay into an electron or neutrino and a quark, producing events with two oppositely charged electrons and at least two jets, or events with an electron, missing transverse momentum and at least two jets. Control data samples are used to validate background predictions from Monte Carlo simulation. In the signal region, the observed event yields are consistent with the background expectations. We exclude at 95% confidence level the production of first generation scalar leptoquark with masses when assuming the branching fraction of a leptoquark to a charged lepton is equal to 1.0 (0.5).
118506676
CO observation of SNR IC 443
We present our 12CO and 13CO mapping observations of SNR IC 443 interacting with molecular clouds. It is the first large-scale high-resolution 13CO mapping observation in the surrounding region. The morphologies of IC 443 in 12CO and 13CO are compared with the optical, infrared, Spitzer far-infrared, X-ray, and neutral atomic gas (HI). We also make comparison and analysis in the kinematics, using the date-cubes of 12CO, 13CO and HI, to help distinguish the complicated gas motions in the shocked regions. Based on the work of Wang & Scoville (1992), we present a new model to explain the coexistence of multiple shocks with different speeds in a pc-scale region at the central clump B. We test this new model by analyzing the HI and CO distribution in both velocity and space domain. We also establish the relationship between the dissociation rate of shocked molecular gas and the shock velocity in this region. Finally, we derive the optical depth of 12CO with the 13CO spectra in clump B, and discuss the validity of the assumption of optically thin emission for the shocked 12CO.