CMS-PAS-EXO-16-023 | ||
Search for the third-generation scalar leptoquarks and heavy right-handed neutrinos in τℓτhjj final states in pp collisions at 13 TeV | ||
CMS Collaboration | ||
August 2016 | ||
Abstract: A search is performed for the third-generation scalar leptoquarks and heavy right handed neutrinos in events containing one electron or muon, one hadronically decaying τ lepton, and at least two jets, using a √s= 13 TeV pp collision data sample corresponding to 12.9 fb−1 collected by the CMS detector at the LHC in 2016. The number of observed events is found to be in agreement with the standard model prediction in both search analyses. A 95% CL limit is set on the product of the leptoquark pair production cross section and β2, where β is the branching fraction of the leptoquark decay to a τ lepton and a b quark. Assuming β=1, the third-generation leptoquarks with masses below 900 GeV are excluded at 95% CL. The right-handed neutrinos are searched in decays of right-handed WR bosons. The heavy right-handed neutrinos are excluded at 95% CL for a range of neutrino masses below the WR mass, dependent on the value of MWR. Assuming the mass of neutrino to be half of the mass of W boson, W boson masses below 3.2 TeV are excluded at 95% CL. | ||
Links:
CDS record (PDF) ;
CADI line (restricted) ;
These preliminary results are superseded in this paper, JHEP 07 (2017) 121. The superseded preliminary plots can be found here. |
Figures | |
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Figure 1-a:
Distribution in ST observed in the μτh (a,c) and eτh (b,d) channel of the LQ (a,b) and heavy RH neutrino (c,d) analysis, compared to the expected SM background contribution and to a hypothetic LQ signal of mass mLQ= 900 GeV and a hypothetic heavy RH neutrino signal of mass mWR= 3 TeV. A binned maximum likelihood fit is performed to the ST distribution. ``Electroweak" background is the sum of W boson, Z boson, and dibosons. The uncertainty bands represent the sum of statistical and systematic uncertainties, added in quadrature. |
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Figure 1-b:
Distribution in ST observed in the μτh (a,c) and eτh (b,d) channel of the LQ (a,b) and heavy RH neutrino (c,d) analysis, compared to the expected SM background contribution and to a hypothetic LQ signal of mass mLQ= 900 GeV and a hypothetic heavy RH neutrino signal of mass mWR= 3 TeV. A binned maximum likelihood fit is performed to the ST distribution. ``Electroweak" background is the sum of W boson, Z boson, and dibosons. The uncertainty bands represent the sum of statistical and systematic uncertainties, added in quadrature. |
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Figure 1-c:
Distribution in ST observed in the μτh (a,c) and eτh (b,d) channel of the LQ (a,b) and heavy RH neutrino (c,d) analysis, compared to the expected SM background contribution and to a hypothetic LQ signal of mass mLQ= 900 GeV and a hypothetic heavy RH neutrino signal of mass mWR= 3 TeV. A binned maximum likelihood fit is performed to the ST distribution. ``Electroweak" background is the sum of W boson, Z boson, and dibosons. The uncertainty bands represent the sum of statistical and systematic uncertainties, added in quadrature. |
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Figure 1-d:
Distribution in ST observed in the μτh (a,c) and eτh (b,d) channel of the LQ (a,b) and heavy RH neutrino (c,d) analysis, compared to the expected SM background contribution and to a hypothetic LQ signal of mass mLQ= 900 GeV and a hypothetic heavy RH neutrino signal of mass mWR= 3 TeV. A binned maximum likelihood fit is performed to the ST distribution. ``Electroweak" background is the sum of W boson, Z boson, and dibosons. The uncertainty bands represent the sum of statistical and systematic uncertainties, added in quadrature. |
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Figure 2:
Observed and expected 95% CL upper limit on the product of signal cross section times branching fraction, obtained from the combination of eτh and μτh channels, in the LQ analysis. The 1σ and 2σ bands represent the 1 and 2 standard deviation uncertainties on the expected limits. |
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Figure 3:
Observed and expected upper limits at 95% CL on the product of cross section and branching fraction for combined eτ and μτ in heavy right handed neutrino analysis. The 1σ and 2σ bands represent the 1 and 2 standard deviation uncertainties on the expected limits. |
Tables | |
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Table 1:
Systematic uncertainties. Those uncertainties marked with * are treated correlated between μτh and eτh channels. |
Summary |
A search is performed for third generation scalar leptoquarks and for heavy right handed neutrinos in events containing one electron or muon, one hadronically decaying τ lepton, and two or more jets, using a pp collision data at √s= 13 TeV centre-of-mass energy recorded by the CMS detector at the LHC and corresponding to an integrated luminosity of 12.9 fb−1. The events observed in data is found to be in good agreement with the SM prediction in both search analyses. A 95% CL limit is set on the product of the leptoquark pair production cross section and β2, where β denotes the branching fraction of decay of the leptoquark to a τ lepton and a b quark. Assuming β=1, third generation leptoquarks with masses below 900 GeV are excluded at 95% CL. In the heavy RH neutrino analysis, considering WR→τNℓ decay and assuming the mass of heavy neutrino to be half of the mass of WR boson W boson masses below 3.2 TeV are excluded at 95% confidence level. These results improve the limits from the previous searches for third generation leptoquarks and heavy right handed neutrino with τ lepton in final state. |
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Compact Muon Solenoid LHC, CERN |
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