Study of the mass and spin-parity of the Higgs boson candidate via its decays to Z boson pairs

CMS Collaboration

Phys. Rev. Lett. 110, 081803 (2013) PRL
CDS record 1502670


A study is presented of the mass and spin-parity of the new boson recently observed at the LHC at a mass near 125 GeV. An integrated luminosity of 17.3 fb-1, collected by the CMS experiment in proton-proton collisions at center-of-mass energies of 7 and 8 TeV, is used. The measured mass in the ZZ channel, where both Z bosons decay to e or m pairs, is 126.2  0.6 (stat.)  0.2 (syst.) GeV. Combining results from the γγ and ZZ channels, we obtain a mass of 125.8 0.4 (stat), 0.4 (syst) GeV, which improves upon previously published results. At this mass the signal strength μ= σ/σSM is measured to be μ= 0.80 +0.35 -0.28. The angular distributions of the lepton pairs in this channel are sensitive to the spin-parity of the boson. Under the assumption of spin 0, the present data are consistent with the pure scalar hypothesis, while disfavoring the pure pseudoscalar hypothesis.


Image File links Description
png pdf Figure 1: (a) Distribution of four-lepton invariant mass in the range near the 126 GeV resonance. Points represent the observed data, shaded histograms represent the backgrounds, and the open histograms represent the signal expectation. The inset shows the m4l distribution for events with high values of kinematic discriminant KD. (b) Scan of -2Δ lnL versus mH with and without the effect of systematic uncertainties included
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png pdf Figure 2: a) Observed distribution of the DSB (SM Higgs boson versus background) discriminant compared with the background and signal expectations. b) Observed distribution of DPS (JP = 0- versus JP = 0+) compared with expectation, for DSB > 0.5. c) Observed distribution of DGS (JP = 2+ versus JP = 0+) compared with expectation, for DSB > 0.5. Points represent the observed data, shaded histograms represent the background, and the open histogram represent the expectation for a 126 GeV boson with the indicated spin-parity, produced at the SM Higgs boson rate.
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png pdf Expected distribution of -2 ln (L0-/L0+) under the pure pseudoscalar and pure scalar hypotheses (histograms). The arrow indicates the value determined from the observed data.
Topic attachments
I Attachment History Action Size Date Who Comment
PDFpdf spinparity_0mn.pdf r1 manage 137.9 K 2013-02-07 - 11:02 ChristopheOchando  
PNGpng spinparity_0mn.png r1 manage 9.2 K 2013-02-07 - 11:08 ChristopheOchando  
PDFpdf spinparity_1DMassScan.pdf r1 manage 26.5 K 2013-02-07 - 11:02 ChristopheOchando  
PNGpng spinparity_1DMassScan.png r1 manage 24.8 K 2013-02-07 - 11:08 ChristopheOchando  
PDFpdf spinparity_gravi.pdf r1 manage 140.5 K 2013-02-07 - 11:02 ChristopheOchando  
PNGpng spinparity_gravi.png r1 manage 24.9 K 2013-02-07 - 11:08 ChristopheOchando  
PDFpdf spinparity_mzz.pdf r1 manage 39.3 K 2013-02-07 - 11:02 ChristopheOchando  
PNGpng spinparity_mzz.png r1 manage 37.2 K 2013-02-07 - 11:08 ChristopheOchando  
PDFpdf spinparity_pseudo.pdf r1 manage 137.4 K 2013-02-07 - 11:02 ChristopheOchando  
PNGpng spinparity_pseudo.png r1 manage 23.4 K 2013-02-07 - 11:08 ChristopheOchando  
PDFpdf spinparity_super.pdf r1 manage 129.5 K 2013-02-07 - 11:02 ChristopheOchando  
PNGpng spinparity_super.png r1 manage 22.1 K 2013-02-07 - 11:08 ChristopheOchando  
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Topic revision: r3 - 2013-02-25 - ChristopheOchando
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