TOP-14-019 Search for top quark decays t → qH with H → γγ in pp collisions at √s = 8 TeV

Abstract

A search for the decay of a top quark via a flavor-changing neutral current is performed. Top quark-antiquark pair events with one top quark decaying to a bottom quark and a W boson and the other top quark decaying to a charm or up quark and a Higgs boson are explored, where the Higgs boson decays to two photons. Data corresponding to an integrated luminosity of 19.7 fb-1 in proton-proton collisions at √s = 8 TeV collected by the CMS detector at the Large Hadron Collider are analyzed. No significant excess is observed. The observed upper limit on the branching fraction of t → c(u)H is determined to be 0.47(0.42)% at the 95% confidence level while the expected upper limit on the branching fraction of t → c(u)H is 0.71(0.65)% at the 95% confidence level.

Public Document

The CMS Physics Analysis Summary is available here

Figures

mgg_fit_hadronic.png

Figure 1: Selected Mγγ distribution of data and fit result of the hadronic channel. The blue dashed line represents the component of the non-resonant diphoton background while the blue solid line represents the total background. The green and yellow areas represent the regions within one and two standard deviations of the non-resonant diphoton background fit, respectively.


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mgg_fit_leptonic.png

Figure 2: Selected Mγγ distribution of data and fit result of the leptonic channel. The blue dashed line represents the component of the non-resonant diphoton background while the blue solid line represents the total background. The green and yellow areas represent the regions within one and two standard deviations of the non-resonant diphoton background fit, respectively.


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limit_hadronic_T_to_cH.png

Figure 3 (a): Signal strength at 95% CL as a function of the branching fraction B for t → cH of the hadronic channel.


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limit_leptonic_T_to_cH.png

Figure 3 (b): Signal strength at 95% CL as a function of the branching fraction B for t → cH of the leptonic channel.


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limit_combined_T_to_cH.png

Figure 3 (c): Signal strength at 95% CL as a function of the branching fraction B for t → cH of the combined channel.


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limit_hadronic_T_to_uH.png

Figure 3 (d): Signal strength at 95% CL as a function of the branching fraction B for t → uH of the hadronic channel.


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limit_leptonic_T_to_uH.png

Figure 3 (e): Signal strength at 95% CL as a function of the branching fraction B for t → uH of the leptonic channel.


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limit_combined_T_to_uH.png

Figure 3 (f): Signal strength at 95% CL as a function of the branching fraction B for t → uH of the combined channel.


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Tables

efficiencies_yields_hadronic.png

Table 1: Efficiencies for simulated events and event yields in data at various selection stages for the hadronic channel.


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efficiencies_yields_leptonic.png

Table 2: Efficiencies for simulated events and event yields in data at various selection stages for the leptonic channel.


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expected_SM_Higgs_backgrounds.png

Table 3: Expected SM Higgs background events at the 19.7 fb-1 integrated luminosity for the hadronic and leptonic channels.


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systematic_uncertainties.png

Table 4: List of systematic uncertainties.


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numbers_data_background_signal.png

Table 5: Numbers of data, expected background estimations, and expected signal yields in the 100 ≤ Mγγ ≤ 180 GeV region.


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AndreasMeyer - 2015-07-14

Topic attachments
I Attachment History Action Size Date Who Comment
PDFpdf efficiencies_yields_hadronic.pdf r1 manage 25.7 K 2015-07-09 - 10:06 YuehFengLiu  
PNGpng efficiencies_yields_hadronic.png r1 manage 49.9 K 2015-07-09 - 11:18 YuehFengLiu  
PDFpdf efficiencies_yields_leptonic.pdf r1 manage 33.1 K 2015-07-09 - 10:06 YuehFengLiu  
PNGpng efficiencies_yields_leptonic.png r1 manage 62.8 K 2015-07-09 - 11:18 YuehFengLiu  
PDFpdf expected_SM_Higgs_backgrounds.pdf r1 manage 21.9 K 2015-07-09 - 11:18 YuehFengLiu  
PNGpng expected_SM_Higgs_backgrounds.png r1 manage 47.4 K 2015-07-09 - 11:18 YuehFengLiu  
PDFpdf limit_combined_T_to_cH.pdf r1 manage 14.2 K 2015-07-09 - 10:02 YuehFengLiu  
PNGpng limit_combined_T_to_cH.png r1 manage 17.3 K 2015-07-09 - 10:02 YuehFengLiu  
PDFpdf limit_combined_T_to_uH.pdf r1 manage 14.2 K 2015-07-09 - 10:06 YuehFengLiu  
PNGpng limit_combined_T_to_uH.png r1 manage 17.2 K 2015-07-09 - 10:06 YuehFengLiu  
PDFpdf limit_hadronic_T_to_cH.pdf r1 manage 14.2 K 2015-07-09 - 10:02 YuehFengLiu  
PNGpng limit_hadronic_T_to_cH.png r1 manage 17.1 K 2015-07-09 - 10:02 YuehFengLiu  
PDFpdf limit_hadronic_T_to_uH.pdf r1 manage 14.2 K 2015-07-09 - 10:06 YuehFengLiu  
PNGpng limit_hadronic_T_to_uH.png r1 manage 16.9 K 2015-07-09 - 10:06 YuehFengLiu  
PDFpdf limit_leptonic_T_to_cH.pdf r1 manage 14.4 K 2015-07-09 - 10:02 YuehFengLiu  
PNGpng limit_leptonic_T_to_cH.png r1 manage 16.7 K 2015-07-09 - 10:02 YuehFengLiu  
PDFpdf limit_leptonic_T_to_uH.pdf r1 manage 14.4 K 2015-07-09 - 10:06 YuehFengLiu  
PNGpng limit_leptonic_T_to_uH.png r1 manage 16.6 K 2015-07-09 - 10:06 YuehFengLiu  
PDFpdf mgg_fit_hadronic.pdf r1 manage 16.9 K 2015-07-09 - 10:02 YuehFengLiu  
PNGpng mgg_fit_hadronic.png r1 manage 25.3 K 2015-07-09 - 10:02 YuehFengLiu  
PDFpdf mgg_fit_leptonic.pdf r1 manage 15.9 K 2015-07-09 - 10:02 YuehFengLiu  
PNGpng mgg_fit_leptonic.png r1 manage 24.9 K 2015-07-09 - 10:02 YuehFengLiu  
PDFpdf numbers_data_background_signal.pdf r1 manage 24.1 K 2015-07-09 - 11:18 YuehFengLiu  
PNGpng numbers_data_background_signal.png r1 manage 51.7 K 2015-07-09 - 11:18 YuehFengLiu  
PDFpdf systematic_uncertainties.pdf r1 manage 62.9 K 2015-07-09 - 11:18 YuehFengLiu  
PNGpng systematic_uncertainties.png r1 manage 137.1 K 2015-07-09 - 11:18 YuehFengLiu  
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Topic revision: r6 - 2015-07-14 - AndreasMeyer
 
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