Search for a Light Higgs boson in the Z boson plus a Photon Decay Channel

This is a condensed description with plots for the analysis CMS-HIG-13-006

Abstract

A search for a Higgs boson decaying into a Z boson and a photon is described. The analysis is performed using a dataset recorded by the CMS experiment at the LHC from proton-proton collisions at a centre-of-mass energy of 7 and 8 TeV, corresponding to an integrated luminosity of 5.0 and 19.6 fb^-1, respectively. Limits are set on the cross section of a standard model Higgs boson decaying to opposite-sign electron or muon pairs and a photon. The expected exclusion limits at 95% confidence level are between 6 and 19 times the standard model cross section in the mass range of 120 and 150 GeV, and the observed limits are between about 3 and 31 times the standard model cross section.

Main result

A search has been made for a Higgs boson decaying into a Z boson plus a photon in the CMS detector at a centre-of-mass energy of 7 and 8 TeV, and the data sample corresponds to 24.6 fb-1 of integrated luminosity. Events are classified according to four categories according to topology of the leptons and the photon, and the photon shower shape. The main backgrounds (pp to Zg and Drell-Yan+jets) are estimated with data-driven techniques.

The search discussed here is performed over the mass range 120--150 GeV. No excess been found in the current data sample and the first limits on the Higgs production cross-section times the H to Zg branching fraction at the LHC have been derived. The upper cross-section limits for the Higgs production times branching fraction decays into Z plus photon are about an order of magnitude larger than the standard model expectation for mH = 125 GeV. Recent theoretical interpretation of the LHC Higgs data that suggests the Higgs to Zg partial widths is significantly enhanced with respect to standard model expectation can be excluded.

PAS Figures:

Figure Label Description
combinedData_All_2GeV.png png, pdf mllg spectrum in the electron and the muon channels for the 7 and 8 TeV data combined. Also shown is the expected signal due to a 125 GeV standard model Higgs scale by 100 and the sum of the individual fits made to the data for each channel and event class at 7 and 8 TeV.
Pas2GevSigRegion_el2011CAT14.png png, pdf Background model fit to the m_eeg distribution for Event classes 1 and 2 for the year 2011
Pas2GevSigRegion_el2011CAT23.png png, pdf Background model fit to the m_eeg distribution for Event classes 3 and 4 for the year 2011
Pas2GevSigRegion_el2012CAT14.png png, pdf Background model fit to the m_eeg distribution for Event classes 1 and 2 for the year 2012
Pas2GevSigRegion_el2012CAT23.png png, pdf Background model fit to the m_eeg distribution for Event classes 3 and 4 for the year 2012
Pas2GevSigRegion_mu2011CAT14.png png, pdf Background model fit to the m_mumug distribution for Event classes 1 and 2 for the year 2011
Pas2GevSigRegion_mu2011CAT23.png png, pdf Background model fit to the m_mumug distribution for Event classes 3 and 4 for the year 2011
Pas2GevSigRegion_mu2012CAT14.png png, pdf Background model fit to the m_mumug distribution for Event classes 1 and 2 for the year 2012
Pas2GevSigRegion_mu2012CAT23.png png, pdf Background model fit to the m_mumug distribution for Event classes 3 and 4 for the year 2012
limitplot_AnalyticPDF-only.png png, pdf Exclusion limit on the cross section of a SM Higgs boson decaying into Z-boson and a photon as a function of the boson mass based on 5.0 fb-1 at of data taken at 7 TeV and 19.6 fb-1 at 8 TeV.

PAS Tables:

Table Label Description
Table1.png png Luminosity and observed data yields used in the analysis. Expected signal yields are for a 125 GeV SM Higgs boson.
Table2.png png Definition of event classes.
Table3.png png Systematic uncertainties.

Additional Figures:

Figure Label Description
combinedData_All_2GeV_Weighted.png png, pdf mllg spectrum in the electron and the muon channels for the 7 and 8 TeV data combined and weighted by the significance [S/(S+B)] expected at 125 GeV. Also shown is the expected signal due to a 125 GeV standard model Higgs scale by 100 and the sum of the individual fits made to the data for each channel and event class at 7 and 8 TeV. The combined reweighted distributions are then normalized to the original data yield.
limitplot_AnalyticPDF-4.png png, pdf Exclusion limit on the cross section of a SM Higgs boson decaying into Z-boson and a photon as a function of the boson mass based on 5.0 fb-1 at of data taken at 7 TeV and 19.6 fb-1 at 8 TeV and the expect exclusion limit from our previous analysis (HIG-12-049) based on 5.0 fb-1 at of data taken at 7 TeV and 5.0 fb-1 at 8 TeV.
pValueplot.png png, pdf The observed local p-value p0 as a function of the SM Higgs boson mass in the range 120150 GeV.
Topic attachments
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PDFpdf Pas2GevSigRegion_el2011CAT14.pdf r1 manage 32.5 K 2013-02-27 - 23:13 MaydaVelasco  
PNGpng Pas2GevSigRegion_el2011CAT14.png r1 manage 59.4 K 2013-02-27 - 23:13 MaydaVelasco  
PDFpdf Pas2GevSigRegion_el2011CAT23.pdf r1 manage 37.2 K 2013-02-27 - 23:13 MaydaVelasco  
PNGpng Pas2GevSigRegion_el2011CAT23.png r1 manage 54.5 K 2013-02-27 - 23:13 MaydaVelasco  
PDFpdf Pas2GevSigRegion_el2012CAT14.pdf r1 manage 31.3 K 2013-02-27 - 23:13 MaydaVelasco  
PNGpng Pas2GevSigRegion_el2012CAT14.png r1 manage 56.5 K 2013-02-27 - 23:13 MaydaVelasco  
PDFpdf Pas2GevSigRegion_el2012CAT23.pdf r1 manage 38.9 K 2013-02-27 - 23:13 MaydaVelasco  
PNGpng Pas2GevSigRegion_el2012CAT23.png r1 manage 62.7 K 2013-02-27 - 23:13 MaydaVelasco  
PDFpdf Pas2GevSigRegion_mu2011CAT14.pdf r1 manage 32.0 K 2013-02-27 - 23:15 MaydaVelasco  
PNGpng Pas2GevSigRegion_mu2011CAT14.png r1 manage 58.4 K 2013-02-27 - 23:15 MaydaVelasco  
PDFpdf Pas2GevSigRegion_mu2011CAT23.pdf r1 manage 37.2 K 2013-02-27 - 23:13 MaydaVelasco  
PNGpng Pas2GevSigRegion_mu2011CAT23.png r1 manage 56.3 K 2013-02-27 - 23:13 MaydaVelasco  
PDFpdf Pas2GevSigRegion_mu2012CAT14.pdf r1 manage 31.6 K 2013-02-27 - 23:15 MaydaVelasco  
PNGpng Pas2GevSigRegion_mu2012CAT14.png r1 manage 58.6 K 2013-02-27 - 23:15 MaydaVelasco  
PDFpdf Pas2GevSigRegion_mu2012CAT23.pdf r1 manage 38.2 K 2013-02-27 - 23:15 MaydaVelasco  
PNGpng Pas2GevSigRegion_mu2012CAT23.png r1 manage 60.8 K 2013-02-27 - 23:15 MaydaVelasco  
PNGpng Table1.png r1 manage 59.4 K 2013-02-27 - 22:58 MaydaVelasco  
PNGpng Table2.png r1 manage 234.8 K 2013-02-27 - 22:58 MaydaVelasco  
PNGpng Table3.png r1 manage 196.7 K 2013-02-27 - 22:58 MaydaVelasco  
PDFpdf combinedData_All_2GeV.pdf r1 manage 28.7 K 2013-02-27 - 23:24 MaydaVelasco  
PNGpng combinedData_All_2GeV.png r1 manage 144.3 K 2013-02-27 - 23:24 MaydaVelasco  
PDFpdf combinedData_All_2GeV_Weighted.pdf r1 manage 28.9 K 2013-02-27 - 23:24 MaydaVelasco  
PNGpng combinedData_All_2GeV_Weighted.png r1 manage 149.2 K 2013-02-27 - 23:24 MaydaVelasco  
PDFpdf limitplot_AnalyticPDF-4.pdf r1 manage 21.8 K 2013-02-27 - 23:05 MaydaVelasco  
PNGpng limitplot_AnalyticPDF-4.png r1 manage 157.3 K 2013-02-27 - 23:05 MaydaVelasco  
PDFpdf limitplot_AnalyticPDF-only.pdf r1 manage 21.4 K 2013-02-27 - 23:05 MaydaVelasco  
PNGpng limitplot_AnalyticPDF-only.png r1 manage 143.8 K 2013-02-27 - 23:05 MaydaVelasco  
PDFpdf pValueplot.pdf r1 manage 19.1 K 2013-02-28 - 15:15 MaydaVelasco  
PNGpng pValueplot.png r1 manage 105.0 K 2013-02-28 - 15:15 MaydaVelasco  
PDFpdf pValueplot_BkgModelPolOnly.pdf r1 manage 19.1 K 2013-02-27 - 23:41 MaydaVelasco  
PNGpng pValueplot_BkgModelPolOnly.png r1 manage 105.4 K 2013-02-27 - 23:41 MaydaVelasco  
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