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 |
|
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. |
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png, pdf |
Background model fit to the m_eeg distribution for Event classes 1 and 2 for the year 2011 |
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png, pdf |
Background model fit to the m_eeg distribution for Event classes 3 and 4 for the year 2011 |
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png, pdf |
Background model fit to the m_eeg distribution for Event classes 1 and 2 for the year 2012 |
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png, pdf |
Background model fit to the m_eeg distribution for Event classes 3 and 4 for the year 2012 |
|
png, pdf |
Background model fit to the m_mumug distribution for Event classes 1 and 2 for the year 2011 |
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png, pdf |
Background model fit to the m_mumug distribution for Event classes 3 and 4 for the year 2011 |
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png, pdf |
Background model fit to the m_mumug distribution for Event classes 1 and 2 for the year 2012 |
|
png, pdf |
Background model fit to the m_mumug distribution for Event classes 3 and 4 for the year 2012 |
|
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 |
|
png |
Definition of event classes. |
|
png |
Luminosity and observed data yields used in the analysis. Expected signal yields are for a 125 GeV SM Higgs boson. |
|
png |
Systematic uncertainties. |
Additional Figures:
Figure |
Label |
Description |
|
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. |
|
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. * |
|
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. * |
|
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. |
|
png, pdf |
The observed local p-value p0 as a function of the SM Higgs boson mass in the range 120–150 GeV. |