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CMS Physics Analysis Summaries

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2015-06-30
14:53
Nuclear modification of Y states in PbPb /CMS Collaboration
Yields of $\Upsilon$(1S), $\Upsilon$(2S) and $\Upsilon$(3S) mesons are measured in the CMS experiment via their $\mu^+ \mu^-$ decays, for bottomonium rapidity $|y|<2.4$, in PbPb and pp collisions at the same energy, $\sqrt{s_{\rm NN}} = 2.76$~TeV. The CMS detector was used to collect integrated luminosity of 166~$\mu$b$^{-1}$ for PbPb and 5.4~pb$^{-1}$ for pp, corresponding to a similar total number of nucleon-nucleon collisions. Differential cross sections and nuclear modification factors are reported as functions of rapidity and transverse momentum, as well as collision centrality, for the $\Upsilon$(1S) and the $\Upsilon$(2S). [...]
CMS-PAS-HIN-15-001.- Geneva : CERN, 2015 Figure_001-a: PDF; Figure_001-b: PDF; Figure_002-a: PDF; Figure_002-b: PDF; Figure_003-a: PDF; Figure_003-b: PDF; Figure_004-a: PDF; Figure_004-b: PDF; Figure_005: PDF; Fulltext in PDF: PDF;

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2015-06-30
14:53
Measurement of the YnS polarizations in pp collisions as a function of charged particle multiplicity /CMS Collaboration
As a first step in a broad study of QCD medium effects on quarkonium polarization, the polarizations of the $\Upsilon$(1S), $\Upsilon$(2S), and $\Upsilon$(3S) mesons are measured in proton-proton collisions at \mbox{$\sqrt{s} = 7$\,TeV} as a function of the charged particle multiplicity, $N_{\rm ch}$. The measurements are performed using a dimuon data sample collected in 2011 by the CMS experiment, corresponding to an integrated luminosity of 4.9\,fb$^{-1}$. The results are extracted from the analysis of the dimuon decay angular distributions, analyzed in three different polarization frames; they are presented as a function of $N_{\rm ch}$, for two ranges in $\Upsilon$ transverse momentum ($10 < p_{\rm T} < 15$ and $15 < p_{\rm T} < 35$\,GeV), integrated within the rapidity range $|y|<1.2$. The measurement of the polarization parameters $\lambda_\vartheta$, $\lambda_\varphi$ and $\lambda_{\vartheta\varphi}$ is complemented by the determination of the frame-invariant quantity $\tilde{\lambda}$, which provides a very useful intrinsic test of the reliability of the whole analysis chain. The polarizations do not show significant changes as a function of $N_{\rm ch}$, excluding strong changes of the production processes between low- and high-multiplicity pp collisions..
CMS-PAS-HIN-15-003.- Geneva : CERN, 2015 Figure_001: PDF; Figure_002: PDF; Figure_003-a: PDF; Figure_003-b: PDF; Figure_004: PDF; Figure_005: PDF; Fulltext in PDF: PDF;

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2015-06-30
14:26
Jet Fragmentation Function in pPb Collisions at sqrt(sNN) = 5.02 TeV and pp Collisions at sqrt(s) = 2.76 and 7 TeV /CMS Collaboration
The fragmentation function of inclusive jets in the pPb collision at $\sqrt{s_{NN}} = 5.02\:\mathrm{TeV}$ is studied, with a dataset corresponding to an integrated luminosity of $31\:\mathrm{nb}^{-1}$. In order to study possible nuclear effects in jet production, this is compared to an pp reference constructed based on the $\sqrt{s} = 2.76\:\mathrm{TeV}$ and $\sqrt{s} = 7\:\mathrm{TeV}$ data, where the fragmentation function is adjusted to the expected flavor mixture at $\sqrt{s} = 5.02\:\mathrm{TeV}$ [...]
CMS-PAS-HIN-15-004.- Geneva : CERN, 2015 Figure_001-a: PDF; Figure_001-b: PDF; Figure_001-c: PDF; Figure_002: PDF; Figure_003: PDF; Figure_004: PDF; Figure_005: PDF; Figure_006: PDF; Figure_007: PDF; Figure_008: PDF; Figure_009: PDF; Figure_010: PDF; Figure_011: PDF; Figure_012: PDF; Figure_013: PDF; Figure_014-a: PDF; Figure_014-b: PDF; Figure_015: PDF; Fulltext in PDF: PDF;

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2015-06-27
17:29
Dijet production with a large rapidity gap between the jets /CMS Collaboration
Events with no particles produced between two leading jets have been studied in pp collisions at $\sqrt{s}=7$ TeV, for jets with $p_\mathrm{T}>40$ GeV and $1.5<|\eta|<4.5$, reconstructed in opposite hemispheres of the detector. The ratio of the yield for these large rapidity gap events to that for inclusive dijet events has been measured as a function of the transverse momentum of the second-leading jet and the size of the pseudorapidity interval between the jets. [...]
CMS-PAS-FSQ-12-001.- Geneva : CERN, 2015 Figure_001: PDF; Figure_002: JPG; Figure_003-a: PDF; Figure_003-b: PDF; Figure_003-c: PDF; Figure_004-a: PDF; Figure_004-b: PDF; Figure_004-c: PDF; Figure_004-d: PDF; Figure_004-e: PDF; Figure_004-f: PDF; Figure_005: PDF; Figure_006-a: PDF; Figure_006-b: PDF; Figure_007-a: PDF; Figure_007-b: PDF; Figure_007-c: PDF; Figure_008: PDF; Figure_009: PDF; Figure_010-a: PDF; Figure_010-b: PDF; Figure_010-c: PDF; Fulltext in PDF: PDF;

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2015-06-16
14:19
Evidence for exclusive gamma-gamma to W+ W- production and constraints on Anomalous Quartic Gauge Couplings at sqrt-s = 8 TeV /CMS Collaboration
A search for exclusive or quasi-exclusive $\gamma\gamma \rightarrow W^{+}W^{-}$ production, $pp \rightarrow p^{(*)}W^{+}W^{-}p^{(*)}\to p^{(*)}\mu^{\pm}e^{\mp}p^{(*)}$, at $\sqrt{s}$~=~8~TeV is reported using data corresponding to an integrated luminosity of 19.7~fb$^{-1}$. Events are selected by requiring the presence of an electron-muon pair with large transverse momentum $p_{T}(\mu^{\pm}e^{\mp})>30~$GeV and no associated charged particles detected from the same vertex. [...]
CMS-PAS-FSQ-13-008.- Geneva : CERN, 2015 Figure_001-a: PDF; Figure_001-b: PDF; Figure_001-c: PDF; Figure_002-a: PDF; Figure_002-b: PDF; Figure_003-a: PDF; Figure_003-b: PDF; Figure_004-a: PDF; Figure_004-b: PDF; Figure_005-a: PDF; Figure_005-b: PDF; Figure_006-a: PDF; Figure_006-b: PDF; Figure_007-a: PDF; Figure_007-b: PDF; Figure_008-a: PDF; Figure_008-b: PDF; Figure_009-a: PDF; Figure_009-b: PDF; Figure_009-c: PDF; Figure_010: PDF; Fulltext in PDF: PDF;

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2015-06-10
19:03
Measurement of spin correlations in top pair events in the lepton + jets channel with the matrix element method at $8 \text{TeV}$ /CMS Collaboration
The consistency of the top quark pair events produced with standard model (SM) correlated spins is tested in the muon+jets final state. The events are obtained from $pp$ collisions at a center of mass energy of $\sqrt{s} = 8 \text{ TeV}$, corresponding to an integrated luminosity of $\int Ldt\, =\, 19.7\, \text{fb}^{-1}$, collected with the Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC). The data agree with the SM hypothesis within 2.2 $\sigma$ (standard deviation) and agree with the uncorrelated hypothesis within 2.9 $\sigma$ based on a hypothesis testing procedure. [...]
CMS-PAS-TOP-13-015.- Geneva : CERN, 2015 Figure_001-a: PDF; Figure_001-b: PDF; Figure_002: PDF; Figure_003-a: PDF; Figure_003-b: PDF; Figure_004: PDF; Figure_005: PDF; Figure_006: PDF; Fulltext in PDF: PDF;

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2015-05-29
18:33
Search for Lepton Flavor Violation in Z decays in pp collisions at sqrt(s)=8 TeV /CMS Collaboration
A search for lepton flavor violation in Z boson decays to one electron and one muon is performed. The data sample of proton-proton collisions at $\sqrt{s}=8$ TeV collected by the CMS detector corresponds to an integrated luminosity of $19.7~\text{fb}^{-1}$. [...]
CMS-PAS-EXO-13-005.- Geneva : CERN, 2015 Figure_001: PDF; Figure_002-a: PDF; Figure_002-b: PDF; Figure_003-a: PDF; Figure_003-b: PDF; Fulltext in PDF: PDF;

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2015-05-29
18:29
Search for displaced photons using conversions at 8 TeV /CMS Collaboration
A search is performed for long-lived neutral particles decaying to photons and invisible particles. An example of a physics process leading to such a signature is the decay of the lightest neutralino with nonzero lifetime into a gravitino and a photon, as predicted by gauge-mediated supersymmetric models. The search is based on events containing at least two photons of which at least one has converted to an $e^{+}e^{-}$ pair, at least two jets, and missing transverse energy. The transverse impact parameter can be reconstructed using photons converting into $e^{+}e^{-}$ pairs. We consider scenarios in which the neutralino has a mean lifetime between $c\tau =$ 0.4 and 100 cm. The analysis was performed on a data sample collected by the CMS experiment at the LHC in 2012 at center-of-mass energy $\sqrt{s}=8$ TeV and corresponds to an integrated luminosity of $19.7$ fb$^{-1}$ of proton--proton collisions..
CMS-PAS-EXO-14-017.- Geneva : CERN, 2015 Figure_001-a: PDF; Figure_001-b: PDF; Figure_002: PDF; Figure_003: PDF; Figure_004: PDF; Figure_005: PDF; Figure_006: PDF; Figure_007: PDF; Fulltext in PDF: PDF;

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2015-05-28
07:54
Measurement of dijet azimuthal decorrelations in pp collisions at sqrt(s) = 8 TeV /CMS Collaboration
A measurement of dijet azimuthal decorrelations between the two jets with the largest transverse momenta is presented for seven regions of leading jet transverse momenta up to 2.2 TeV. The analysis is based on the full data set of proton-proton collisions acquired by the CMS experiment at the LHC during 2012 at a centre-of-mass energy of 8 TeV. [...]
CMS-PAS-SMP-14-015.- Geneva : CERN, 2015 Figure_001-a: PDF; Figure_001-b: PDF; Figure_002: PDF; Figure_003: PDF; Figure_004: PDF; Figure_005: PDF; Fulltext in PDF: PDF;

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2015-05-22
12:13
Search for High-Mass Diphoton Resonances in pp Collisions at sqrt(s)=8 TeV with the CMS Detector /CMS Collaboration
A search for high-mass diphoton resonances is performed in proton-proton collisions at $\sqrt{s}=8$~TeV, with data corresponding to an integrated luminosity of 19.5~fb$^{-1}$, collected by the CMS detector at the CERN Large Hadron Collider. Such a diphoton resonance could be a signature of an excited state of the graviton in the Randall-Sundrum scenario with a warped extra dimension of space. [...]
CMS-PAS-EXO-12-045.- Geneva : CERN, 2015 Figure_001-a: PNG; Figure_001-b: PNG; Figure_001-c: PNG; Figure_002-a: PNG; Figure_002-b: PNG; Figure_002-c: PNG; Figure_003: PNG; Fulltext in PDF: PDF;

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