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 in 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.

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-color.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-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 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. * Alternative colors for the one and two sigma band -- used in HIG-12-049. *
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. * Alternative colors for the one and two sigma band. *
limitplot_AnalyticPDF_InCludingOld-color.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
I Attachment History Action Size Date Who Comment
PDFpdf Pas2GevSigRegion_el2011CAT14.pdf r2 r1 manage 31.1 K 2013-03-03 - 13:41 MaydaVelasco  
PNGpng Pas2GevSigRegion_el2011CAT14.png r2 r1 manage 53.5 K 2013-03-03 - 13:43 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 r2 r1 manage 31.1 K 2013-03-03 - 13:48 MaydaVelasco  
PNGpng Pas2GevSigRegion_mu2011CAT14.png r2 r1 manage 55.9 K 2013-03-03 - 13:48 MaydaVelasco  
PDFpdf Pas2GevSigRegion_mu2011CAT23.pdf r2 r1 manage 36.2 K 2013-03-03 - 13:48 MaydaVelasco  
PNGpng Pas2GevSigRegion_mu2011CAT23.png r2 r1 manage 53.5 K 2013-03-03 - 13:48 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 r2 r1 manage 38.3 K 2013-03-03 - 13:50 MaydaVelasco  
PNGpng Pas2GevSigRegion_mu2012CAT23.png r2 r1 manage 61.0 K 2013-03-03 - 13:50 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-color.pdf r1 manage 21.4 K 2013-03-05 - 02:42 MaydaVelasco  
PNGpng limitplot_AnalyticPDF-color.png r1 manage 141.2 K 2013-03-05 - 02:42 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 limitplot_AnalyticPDF_InCludingOld-color.pdf r1 manage 21.8 K 2013-03-05 - 02:42 MaydaVelasco  
PNGpng limitplot_AnalyticPDF_InCludingOld-color.png r1 manage 154.1 K 2013-03-05 - 02:42 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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