Compact Muon Solenoid
LHC, CERN
Visit us: CMS Public Website, CMS Physics ;
Contact us: CMS Publications Committee
| CMS-PAS-EXO-16-025 | ||
| Search for high-mass resonances in the $\mathrm{Z(q\overline{q})}\gamma$ final state at $ \sqrt{s} = $ 8 TeV | ||
| CMS Collaboration | ||
| August 2016 | ||
| Abstract: A search for massive resonances decaying to a Z boson and a photon is performed in events with a hadronically decaying Z boson candidate, using jet substructure and advanced b-tagging techniques. Results are based on a sample of proton-proton collisions at a center-of-mass energy of 8 TeV at the LHC corresponding to an integrated luminosity of 19.7 fb$^{-1}$ collected by the CMS detector. Spin-0 resonances with various widths and with masses in a range between 650 GeV and 2.5 TeV are probed. Since no signal is found, the results are presented in terms of an upper limit on the production cross section of such resonances. | ||
|
Links:
CDS record (PDF) ;
CADI line (restricted) ;
These preliminary results are superseded in this paper, PLB 772 (2017) 363. The superseded preliminary plots can be found here. |
||
| Figures & Tables | Summary | Additional Figures | References | CMS Publications |
|---|
| Figures | |
png |
Figure 1-a:
Full acceptance times efficiency (including $\mathcal {B}( {\mathrm {Z}} \to { {\mathrm {q}} {\overline {\mathrm {q}}} } $)) of the two signal categories for resonances with different widths as a function of resonance mass. Points show the numbers extracted from the Monte Carlo simulation, curves show the fit of the values with a polynomial. |
png |
Figure 1-b:
Full acceptance times efficiency (including $\mathcal {B}( {\mathrm {Z}} \to { {\mathrm {q}} {\overline {\mathrm {q}}} } $)) of the two signal categories for resonances with different widths as a function of resonance mass. Points show the numbers extracted from the Monte Carlo simulation, curves show the fit of the values with a polynomial. |
png |
Figure 2-a:
Fits on $ {M_{\text {Z}\gamma }} $ invariant mass spectra in signal region for a) anti-b-tagged and b) b-tagged categories. No events have been found above 2.5 TeV . The results of the fits to the two categories with the parametric background shape are shown. The difference between the yield measured in data and the estimate from the fit is divided by the statistical uncertainty on the measurement and reported in the lower panel. |
png |
Figure 2-b:
Fits on $ {M_{\text {Z}\gamma }} $ invariant mass spectra in signal region for a) anti-b-tagged and b) b-tagged categories. No events have been found above 2.5 TeV . The results of the fits to the two categories with the parametric background shape are shown. The difference between the yield measured in data and the estimate from the fit is divided by the statistical uncertainty on the measurement and reported in the lower panel. |
png pdf |
Figure 3-a:
Expected and observed limits on the narrow spin-0 resonance production cross section times branching fraction $\mathrm {X} \rightarrow \mathrm {Z}\gamma $ obtained for the a)anti-b-tagged and b)b-tagged categories. |
png pdf |
Figure 3-b:
Expected and observed limits on the narrow spin-0 resonance production cross section times branching fraction $\mathrm {X} \rightarrow \mathrm {Z}\gamma $ obtained for the a)anti-b-tagged and b)b-tagged categories. |
png pdf |
Figure 4-a:
Expected and observed limits on the wide spin-0 resonance production cross section times branching fraction $\mathrm {X} \rightarrow \mathrm {Z}\gamma $ obtained for the a)anti-b-tagged and b)b-tagged categories. |
png pdf |
Figure 4-b:
Expected and observed limits on the wide spin-0 resonance production cross section times branching fraction $\mathrm {X} \rightarrow \mathrm {Z}\gamma $ obtained for the a)anti-b-tagged and b)b-tagged categories. |
png pdf |
Figure 5-a:
Expected and observed limits on the a) narrow and b) wide spin-0 resonance production cross section times branching fraction $\mathrm {X} \rightarrow \mathrm {Z}\gamma $. |
png pdf |
Figure 5-b:
Expected and observed limits on the a) narrow and b) wide spin-0 resonance production cross section times branching fraction $\mathrm {X} \rightarrow \mathrm {Z}\gamma $. |
| Tables | |
png pdf |
Table 1:
Summary of the sources of uncertainties and their effects on the yield variation. |
png pdf |
Table 2:
Expected limits, in fb, for two categories of the analysis, as well as the results from combined asymptotic limits, for a narrow resonance. |
| Summary |
| We have presented a search for a possible resonance in the mass range from 650 GeV to 2.5 TeV decaying into a Z boson and a photon, where the Z boson further decays to a pair of quarks, merged in a single jet. The search is based on the analysis of pp collision data collected at $ \sqrt{s} = $ 8 TeV and corresponding to an integrated luminosity of 19.7 fb$^{-1}$. The final results were obtained by combining the observations from searches in two exclusive categories of the events with or without a $\mathrm{ Z }\to\mathrm{ b \bar{b} }$ candidate. The observed data was found to be compatible with the standard model prediction. The final results are expressed in terms of expected upper limits at 95% CL on the production cross section of a new resonance. |
| Additional Figures | |
png pdf |
Additional Figure 1:
Overlaid expected and observed limits on the narrow spin-0 resonance production cross section times branching fraction $\mathrm {X} \rightarrow \mathrm {Z}\gamma $ obtained with the hadronic $\mathrm {Z}({\rm q \bar{q} } )\gamma $ analysis in CMS-PAS-EXO-16-020 for 2015 data, CMS-PAS-EXO-16-025 for 2012 data, and CMS-PAS-EXO-16-035 for 2016 data. The scaling of upper limits from EXO-16-025 (8TeV) takes into account the different parton luminosities at different center of mass energies, which have been calculated with NNPDF2.3 parton distributions. The parametrization of parton luminosity ratio is identicle to the one used in CMS-PAS-EXO-16-021 (Combination of searches for high-mass resonances in $\mathrm {Z}({\rm l \bar{l} })\gamma $ final state at $\sqrt {s} =$ 8 TeV and $\sqrt {s} =$ 13 TeV). |
| References | ||||
| 1 | ATLAS Collaboration | Measurements of $ \mathrm{ W }\gamma $ and $ \mathrm{ Z }\gamma $ production in pp collisions at $ \sqrt{s} $=7 TeV with the ATLAS detector at the LHC | PRD 87 (2013) 112003, , [Erratum: Phys. Rev.D91,no.11,119901(2015)] | 1302.1283 |
| 2 | ATLAS Collaboration | Search for new resonances in $ W\gamma $ and $ Z\gamma $ final states in $ pp $ collisions at $ \sqrt s=8 $ TeV with the ATLAS detector | PLB 738 (2014) 428 | 1407.8150 |
| 3 | CMS Collaboration | Search for a Higgs boson decaying into a Z and a photon in pp collisions at sqrt(s) = 7 and 8 TeV | PLB 726 (2013) 587 | CMS-HIG-13-006 1307.5515 |
| 4 | ATLAS Collaboration | Search for Higgs boson decays to a photon and a Z boson in pp collisions at $ \sqrt{s} $=7 and 8 TeV with the ATLAS detector | PLB 732 (2014) 8 | 1402.3051 |
| 5 | CMS Collaboration | Search for scalar resonances in the 200--1200 GeV mass range decaying into a Z and a photon in pp collisions at $ \sqrt{s} = $ 8 TeV | CMS-PAS-HIG-16-014 | CMS-PAS-HIG-16-014 |
| 6 | CMS Collaboration | Search for high-mass resonances in $ \mathrm{ Z }\gamma\to e^+e^- \gamma/\mu^+\mu^-\gamma $ final states in proton-proton collisions at $ \sqrt{s} = $ 13 TeV | CMS-PAS-EXO-16-019 | CMS-PAS-EXO-16-019 |
| 7 | CMS Collaboration | Search for high-mass resonances in $ \mathrm{Z}(\mathrm{q}\bar{\mathrm{q}})\gamma $ final state in pp collisions at $ \sqrt{s}=13 \mathrm{TeV} $ with $ 2.7 \mathrm{fb}^{-1} $ | CMS-PAS-EXO-16-020 | CMS-PAS-EXO-16-020 |
| 8 | CMS Collaboration | Combination of searches for high-mass resonances in Zgamma final states in proton-proton collisions at $ \sqrt{s} $ 8 and 13 TeV | CDS | |
| 9 | CMS Collaboration | The CMS experiment at the CERN LHC | JINST 3 (2008) S08004 | CMS-00-001 |
| 10 | CMS Collaboration | Particle-Flow Event Reconstruction in CMS and Performance for Jets, Taus, and MET | CDS | |
| 11 | CMS Collaboration | Commissioning of the Particle-flow Event Reconstruction with the first LHC collisions recorded in the CMS detector | CDS | |
| 12 | CMS Collaboration | Performance of Photon Reconstruction and Identification with the CMS Detector in Proton-Proton Collisions at sqrt(s) = 8 TeV | JINST 10 (2015), no. 08, P08010 | CMS-EGM-14-001 1502.02702 |
| 13 | M. Wobisch and T. Wengler | Hadronization corrections to jet cross-sections in deep inelastic scattering | hep-ph/9907280 | |
| 14 | S. D. Ellis, C. K. Vermilion, and J. R. Walsh | Techniques for improved heavy particle searches with jet substructure | PRD 80 (2009) 051501 | 0903.5081 |
| 15 | S. D. Ellis, C. K. Vermilion, and J. R. Walsh | Recombination Algorithms and Jet Substructure: Pruning as a Tool for Heavy Particle Searches | PRD 81 (2010) 094023 | 0912.0033 |
| 16 | CMS Collaboration | Identification techniques for highly boosted W bosons that decay into hadrons | JHEP 12 (2014) 017 | CMS-JME-13-006 1410.4227 |
| 17 | CMS Collaboration | Performance of b tagging at sqrt(s)=8 TeV in multijet, ttbar and boosted topology events | CMS-PAS-BTV-13-001 | CMS-PAS-BTV-13-001 |
| 18 | ATLAS Collaboration | Search for resonances decaying to photon pairs in 3.2 fb$ ^{-1} $ of pp collisions at $ \sqrt{s} = $ 13 TeV with the ATLAS detector | ATLAS Conference Note ATLAS-CONF-2015-081 | |
| 19 | ATLAS Collaboration | Search for resonances in diphoton events with the ATLAS detector at $ \sqrt{s} = $ 13 TeV | ATLAS Conference Note ATLAS-CONF-2016-018 | |
| 20 | CMS Collaboration | Search for new physics in high mass diphoton events in proton-proton collisions at $ \sqrt{s}= 13 $ TeV | CMS-PAS-EXO-15-004 | CMS-PAS-EXO-15-004 |
| 21 | CMS Collaboration | Search for new physics in high mass diphoton events in 3.3 fb$ ^{-1} $ of proton-proton collisions at $ \sqrt{s} = $ 13 TeV and combined interpretation of searches at 8 TeV and 13 TeV | CMS-PAS-EXO-16-018 | CMS-PAS-EXO-16-018 |
| 22 | T. Sjostrand, S. Mrenna, and P. Z. Skands | A Brief Introduction to PYTHIA 8.1 | CPC 178 (2008) 852 | 0710.3820 |
| 23 | J. Pumplin et al. | New generation of parton distributions with uncertainties from global QCD analysis | JHEP 07 (2002) 012 | hep-ph/0201195 |
| 24 | A. D. Martin, W. J. Stirling, R. S. Thorne, and G. Watt | Parton distributions for the LHC | EPJC 63 (2009) 189 | 0901.0002 |
| 25 | GEANT4 Collaboration | $ Geant 4--a $ simulation toolkit | NIMA 506 (2003) 250 | |
| 26 | P. Dauncey, M. Kenzie, N. Wardle, and G. Davies | Handling uncertainties in background shapes: the discrete profiling method | JINST 10 (2015), no. 04, P04015 | |
| 27 | CMS Collaboration | Observation of the diphoton decay of the Higgs boson and measurement of its properties | EPJC (2014) | |
| 28 | M. J. Oreglia | PhD thesis, Stanford University, 1980 SLAC Report SLAC-R-236 | ||
| 29 | CMS Collaboration | Search for massive resonances decaying into pairs of boosted W and Z bosons at $ \sqrt{s} $ = 13 TeV | CMS-PAS-EXO-15-002 | CMS-PAS-EXO-15-002 |
| 30 | CMS Collaboration | CMS Luminosity Based on Pixel Cluster Counting - Summer 2013 Update | ||
| 31 | A. L. Read | Presentation of search results: The CL$ _S $ technique | JPG 28 (2002) 2693 | |
| 32 | T. Junk | Confidence level computation for combining searches with small statistics | NIMA 434 (1999) 435 | hep-ex/9902006 |
| 33 | ATLAS and CMS Collaborations | Procedure for the LHC Higgs boson search combination in summer 2011 | ATL-PHYS-PUB-2011-011, CMS NOTE-2011/005 | |
|
|
Compact Muon Solenoid LHC, CERN |
|
|
|
|
|
|