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-12-049

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 5.2 fb-1, respectively. Limits are set on the cross section of a standard model Higgs boson decaying to two opposite-sign electron or muon pair and a photon. The expected exclusion limit at 95% confidence level are between 10 and 28 times the standard model cross section in the mass range of 120 and 150 GeV, and the observed limit fluctuates between about 8 and 48 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 10.2 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 115--180 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
leadingPT.pdf png,pdf Transverse momentum for the leading lepton based on simulated events for the total background (Zg and Z+jets) and signal for mH = 125 GeV
trailingPT.pdf png, pdf Transverse momentum for the trailing lepton based on simulated events for the total background (Zg and Z+jets) and signal for mH = 125 GeV
photonPT.pdf png, pdf Transverse momentum for the photon based on simulated events for the total background (Zg and Z+jets) and signal for mH = 125 GeV
el2011CAT14.png png, pdf Background model fit to the m_eeg distribution for Event classes 1 and 2 for the year 2011
el2011CAT23.png png, pdf Background model fit to the m_eeg distribution for Event classes 3 and 4 for the year 2011
el2012CAT14.png png, pdf Background model fit to the m_eeg distribution for Event classes 1 and 2 for the year 2012
el2012CAT23.png png, pdf Background model fit to the m_eeg distribution for Event classes 3 and 4 for the year 2012
mu2011CAT14.png png, pdf Background model fit to the m_mumug distribution for Event classes 1 and 2 for the year 2011
mu2011CAT23.png png, pdf Background model fit to the m_mumug distribution for Event classes 3 and 4 for the year 2011
mu2012CAT14.png png, pdf Background model fit to the m_mumug distribution for Event classes 1 and 2 for the year 2012
mu2012CAT23.png png, pdf Background model fit to the m_mumug distribution for Event classes 3 and 4 for the year 2012
AllIn30_A.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 5.2 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.
Topic attachments
I Attachment History Action Size Date Who Comment
PNGpng 2011_ee.png r2 r1 manage 102.6 K 2012-12-12 - 12:41 LetiziaLus  
PNGpng 2011_mm.png r2 r1 manage 103.3 K 2012-12-12 - 12:41 LetiziaLus  
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PNGpng 2012_mm.png r2 r1 manage 101.0 K 2012-12-12 - 12:41 LetiziaLus  
PDFpdf AllIn30_A.pdf r1 manage 21.1 K 2012-12-12 - 10:44 LetiziaLus  
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PNGpng DCcombiAll_NWCat_8TeV_limitplot.png r1 manage 115.2 K 2012-12-12 - 18:26 LetiziaLus  
PDFpdf ExpPvalue_pValueplot.pdf r1 manage 14.9 K 2012-12-12 - 18:26 LetiziaLus  
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PNGpng diLeptonM_mu2012no_PAS.png r1 manage 63.8 K 2012-12-12 - 10:48 LetiziaLus  
PDFpdf eeEtaCAT14.pdf r1 manage 17.2 K 2012-12-12 - 10:49 LetiziaLus  
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PDFpdf el2011CAT14.pdf r1 manage 30.6 K 2012-12-12 - 10:49 LetiziaLus  
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PDFpdf leadingPT.pdf r1 manage 14.4 K 2012-12-12 - 10:51 LetiziaLus  
PNGpng leadingPT.png r1 manage 91.1 K 2012-12-12 - 18:20 LetiziaLus  
PDFpdf mu2011CAT14.pdf r1 manage 30.8 K 2012-12-12 - 10:51 LetiziaLus  
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PDFpdf mu2011CAT23.pdf r1 manage 30.8 K 2012-12-12 - 10:51 LetiziaLus  
PNGpng mu2011CAT23.png r1 manage 25.1 K 2012-12-12 - 10:58 LetiziaLus  
PDFpdf mu2012CAT14.pdf r1 manage 30.9 K 2012-12-12 - 10:51 LetiziaLus  
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PDFpdf mu2012CAT23.pdf r1 manage 30.9 K 2012-12-12 - 10:51 LetiziaLus  
PNGpng mu2012CAT23.png r1 manage 25.7 K 2012-12-12 - 10:58 LetiziaLus  
PDFpdf mumuEtaCAT14.pdf r1 manage 18.6 K 2012-12-12 - 10:51 LetiziaLus  
PDFpdf mumuEtaCAT25.pdf r1 manage 16.6 K 2012-12-12 - 10:51 LetiziaLus  
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PNGpng origDataMC_EB_2011.png r1 manage 8.9 K 2012-12-12 - 10:53 LetiziaLus  
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PDFpdf photonPT.pdf r1 manage 14.3 K 2012-12-12 - 10:59 LetiziaLus  
PNGpng photonPT.png r1 manage 82.6 K 2012-12-12 - 18:20 LetiziaLus  
PNGpng pvalue.png r1 manage 78.7 K 2012-12-12 - 18:26 LetiziaLus  
PDFpdf trailingPT.pdf r1 manage 14.7 K 2012-12-12 - 10:54 LetiziaLus  
PNGpng trailingPT.png r1 manage 97.6 K 2012-12-12 - 18:20 LetiziaLus  
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