CMSPASEXO17011  
Search for a heavy righthanded W boson and a heavy neutrino in events with two sameflavor leptons and two jets at $\sqrt{s}= $ 13 TeV  
CMS Collaboration  
December 2017  
Abstract: A search for a heavy righthanded W gauge boson and a heavy righthanded neutrino at the CERN LHC has been conducted by the CMS collaboration in events with two sameflavor leptons (e or $\mu$) and two jets, using 2016 protonproton collision data corresponding to an integrated luminosity of 35.9 fb$^{1}$. No excess above the standard model expectation is seen in the invariant mass distribution of the dilepton plus dijet system. Assuming identical couplings and decay branching fractions as the standard model W gauge boson, and that only one heavy neutrino flavor ${\mathrm N}_R$ contributes significantly to the ${\mathrm W}_R$ decay width, the region in the twodimensional ($m_{{\mathrm W}_R}$, $m_{{\mathrm N}_R}$) mass plane excluded at a 95% confidence level extends to approximately $m_{{\mathrm W}_R}= $ 4.4 TeV and covers a large range of neutrino masses below the ${\mathrm W}_R$ boson mass. This analysis provides the most stringent limits to date.  
Links:
CDS record (PDF) ;
inSPIRE record ;
CADI line (restricted) ;
These preliminary results are superseded in this paper, JHEP 05 (2018) 148. The superseded preliminary plots can be found here. 
Figures  
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Figure 1:
Distribution of kinematic quantities for events in the lowdilepton mass control region. The fourobject invariant mass (on the top) and the dilepton transverse momentum (on the bottom) for the DY $\mu \mu $ plus two jets selection are shown on the left. The dilepton mass (on the top) and the scalar sum of all jets $ {p_{\mathrm {T}}} $ (on the bottom) for the DY ee plus two jets selection are shown on the right. The error bands on the MC histograms only include statistical uncertainties. The error bars in the ratio represent the statistical uncertainties of data and MC calculated with the standard error propagation of $\frac {N_d}{N_s}$ given $N_d$ the number of data events in the bin and $N_s$ the number of simulated events in the bin. 
png 
Figure 1a:
Distribution of kinematic quantities for events in the lowdilepton mass control region. The fourobject invariant mass (on the top) and the dilepton transverse momentum (on the bottom) for the DY $\mu \mu $ plus two jets selection are shown on the left. The dilepton mass (on the top) and the scalar sum of all jets $ {p_{\mathrm {T}}} $ (on the bottom) for the DY ee plus two jets selection are shown on the right. The error bands on the MC histograms only include statistical uncertainties. The error bars in the ratio represent the statistical uncertainties of data and MC calculated with the standard error propagation of $\frac {N_d}{N_s}$ given $N_d$ the number of data events in the bin and $N_s$ the number of simulated events in the bin. 
png 
Figure 1b:
Distribution of kinematic quantities for events in the lowdilepton mass control region. The fourobject invariant mass (on the top) and the dilepton transverse momentum (on the bottom) for the DY $\mu \mu $ plus two jets selection are shown on the left. The dilepton mass (on the top) and the scalar sum of all jets $ {p_{\mathrm {T}}} $ (on the bottom) for the DY ee plus two jets selection are shown on the right. The error bands on the MC histograms only include statistical uncertainties. The error bars in the ratio represent the statistical uncertainties of data and MC calculated with the standard error propagation of $\frac {N_d}{N_s}$ given $N_d$ the number of data events in the bin and $N_s$ the number of simulated events in the bin. 
png 
Figure 1c:
Distribution of kinematic quantities for events in the lowdilepton mass control region. The fourobject invariant mass (on the top) and the dilepton transverse momentum (on the bottom) for the DY $\mu \mu $ plus two jets selection are shown on the left. The dilepton mass (on the top) and the scalar sum of all jets $ {p_{\mathrm {T}}} $ (on the bottom) for the DY ee plus two jets selection are shown on the right. The error bands on the MC histograms only include statistical uncertainties. The error bars in the ratio represent the statistical uncertainties of data and MC calculated with the standard error propagation of $\frac {N_d}{N_s}$ given $N_d$ the number of data events in the bin and $N_s$ the number of simulated events in the bin. 
png 
Figure 1d:
Distribution of kinematic quantities for events in the lowdilepton mass control region. The fourobject invariant mass (on the top) and the dilepton transverse momentum (on the bottom) for the DY $\mu \mu $ plus two jets selection are shown on the left. The dilepton mass (on the top) and the scalar sum of all jets $ {p_{\mathrm {T}}} $ (on the bottom) for the DY ee plus two jets selection are shown on the right. The error bands on the MC histograms only include statistical uncertainties. The error bars in the ratio represent the statistical uncertainties of data and MC calculated with the standard error propagation of $\frac {N_d}{N_s}$ given $N_d$ the number of data events in the bin and $N_s$ the number of simulated events in the bin. 
png pdf 
Figure 2:
Kinematic distributions for events in the flavor control region. The dilepton mass (top left), the fourobject mass (top right), the scalar sum of all jets $ {p_{\mathrm {T}}} $ (bottom left) and the number of jets (bottom right) are shown. The error bands on the MC histograms only include statistical uncertainties. The error bars in the ratio represent the statistical uncertainties of data and MC calculated with the standard error propagation of $\frac {N_d}{N_s}$ given $N_d$ the number of data events in the bin and $N_s$ the number of simulated events in the bin. 
png 
Figure 2a:
Kinematic distributions for events in the flavor control region. The dilepton mass (top left), the fourobject mass (top right), the scalar sum of all jets $ {p_{\mathrm {T}}} $ (bottom left) and the number of jets (bottom right) are shown. The error bands on the MC histograms only include statistical uncertainties. The error bars in the ratio represent the statistical uncertainties of data and MC calculated with the standard error propagation of $\frac {N_d}{N_s}$ given $N_d$ the number of data events in the bin and $N_s$ the number of simulated events in the bin. 
png 
Figure 2b:
Kinematic distributions for events in the flavor control region. The dilepton mass (top left), the fourobject mass (top right), the scalar sum of all jets $ {p_{\mathrm {T}}} $ (bottom left) and the number of jets (bottom right) are shown. The error bands on the MC histograms only include statistical uncertainties. The error bars in the ratio represent the statistical uncertainties of data and MC calculated with the standard error propagation of $\frac {N_d}{N_s}$ given $N_d$ the number of data events in the bin and $N_s$ the number of simulated events in the bin. 
png 
Figure 2c:
Kinematic distributions for events in the flavor control region. The dilepton mass (top left), the fourobject mass (top right), the scalar sum of all jets $ {p_{\mathrm {T}}} $ (bottom left) and the number of jets (bottom right) are shown. The error bands on the MC histograms only include statistical uncertainties. The error bars in the ratio represent the statistical uncertainties of data and MC calculated with the standard error propagation of $\frac {N_d}{N_s}$ given $N_d$ the number of data events in the bin and $N_s$ the number of simulated events in the bin. 
png 
Figure 2d:
Kinematic distributions for events in the flavor control region. The dilepton mass (top left), the fourobject mass (top right), the scalar sum of all jets $ {p_{\mathrm {T}}} $ (bottom left) and the number of jets (bottom right) are shown. The error bands on the MC histograms only include statistical uncertainties. The error bars in the ratio represent the statistical uncertainties of data and MC calculated with the standard error propagation of $\frac {N_d}{N_s}$ given $N_d$ the number of data events in the bin and $N_s$ the number of simulated events in the bin. 
png pdf 
Figure 3:
Fourobject mass distribution in the signal region for the electron channel on the left and for the muon channel on the right. The error bands on the MC histograms only include statistical uncertainties. The error bars in the ratio represent the statistical uncertainties of data and MC calculated with the standard error propagation of $\frac {N_d}{N_s}$ given $N_d$ the number of data events in the bin and $N_s$ the number of simulated events in the bin. The gray error band around 1 represents instead the systematic uncertainty of the simulation. 
png 
Figure 3a:
Fourobject mass distribution in the signal region for the electron channel on the left and for the muon channel on the right. The error bands on the MC histograms only include statistical uncertainties. The error bars in the ratio represent the statistical uncertainties of data and MC calculated with the standard error propagation of $\frac {N_d}{N_s}$ given $N_d$ the number of data events in the bin and $N_s$ the number of simulated events in the bin. The gray error band around 1 represents instead the systematic uncertainty of the simulation. 
png 
Figure 3b:
Fourobject mass distribution in the signal region for the electron channel on the left and for the muon channel on the right. The error bands on the MC histograms only include statistical uncertainties. The error bars in the ratio represent the statistical uncertainties of data and MC calculated with the standard error propagation of $\frac {N_d}{N_s}$ given $N_d$ the number of data events in the bin and $N_s$ the number of simulated events in the bin. The gray error band around 1 represents instead the systematic uncertainty of the simulation. 
png pdf 
Figure 4:
Limit on $\sigma (pp\rightarrow \mathrm{W}_{R}) \times BR(\mathrm{W}_{R} \rightarrow \ell \ell \text {jj})$ with systematic uncertainties for the electron channel on the left and for the muon channel on the right. The inner (green) band and the outer (yellow) band indicate the regions containing, respectively, the 68% and 95% of the distribution of limits expected under the signal plus background hypothesis. Righthanded bosons with $m_{\mathrm{W}_{R}} < $ 4.4 TeV are excluded. 
png pdf 
Figure 4a:
Limit on $\sigma (pp\rightarrow \mathrm{W}_{R}) \times BR(\mathrm{W}_{R} \rightarrow \ell \ell \text {jj})$ with systematic uncertainties for the electron channel on the left and for the muon channel on the right. The inner (green) band and the outer (yellow) band indicate the regions containing, respectively, the 68% and 95% of the distribution of limits expected under the signal plus background hypothesis. Righthanded bosons with $m_{\mathrm{W}_{R}} < $ 4.4 TeV are excluded. 
png pdf 
Figure 4b:
Limit on $\sigma (pp\rightarrow \mathrm{W}_{R}) \times BR(\mathrm{W}_{R} \rightarrow \ell \ell \text {jj})$ with systematic uncertainties for the electron channel on the left and for the muon channel on the right. The inner (green) band and the outer (yellow) band indicate the regions containing, respectively, the 68% and 95% of the distribution of limits expected under the signal plus background hypothesis. Righthanded bosons with $m_{\mathrm{W}_{R}} < $ 4.4 TeV are excluded. 
png pdf 
Figure 5:
Upper limit on the cross section for different $ \mathrm{W}_{R} $ and ${{{\mathrm N}_R}}$ mass hypothesis, for the electron channel on the left and for the muon channel on the right. The expected and observed exclusions are shown as the dotted (blue) curve and the solid (red) curve, respectively. The thin dotted (blue) curves indicate the region containing the 68% of the distribution of limits expected under the signal plus background hypothesys. 
png pdf 
Figure 5a:
Upper limit on the cross section for different $ \mathrm{W}_{R} $ and ${{{\mathrm N}_R}}$ mass hypothesis, for the electron channel on the left and for the muon channel on the right. The expected and observed exclusions are shown as the dotted (blue) curve and the solid (red) curve, respectively. The thin dotted (blue) curves indicate the region containing the 68% of the distribution of limits expected under the signal plus background hypothesys. 
png pdf 
Figure 5b:
Upper limit on the cross section for different $ \mathrm{W}_{R} $ and ${{{\mathrm N}_R}}$ mass hypothesis, for the electron channel on the left and for the muon channel on the right. The expected and observed exclusions are shown as the dotted (blue) curve and the solid (red) curve, respectively. The thin dotted (blue) curves indicate the region containing the 68% of the distribution of limits expected under the signal plus background hypothesys. 
Tables  
png pdf 
Table 1:
Transfer factor applied to the number of events in flavor control region to estimate the number of ${\mathrm{t} {}\mathrm{\bar{t}}}$ events in the $\mathrm{e} \mathrm{e} \text {jj}$ and $\mu \mu \text {jj}$ signal regions. 
png pdf 
Table 2:
Effect of object reconstruction's systematic uncertainties on signal and background yields. 
png pdf 
Table 3:
Uncertainties affecting $m_{\ell \ell \text {jj}}$ shape and normalization. The $ {\mathrm{t} {}\mathrm{\bar{t}}} $ SFs affect the $ {\mathrm{t} {}\mathrm{\bar{t}}} $ background, the DY PDF, factorization, and renormalization scales affect the DY + jets background and the luminosity affects both signal and backgrounds. 
png pdf 
Table 4:
Observed number of events and magnitudes of systematic and statistical uncertainties for the expected events in different $ \mathrm{W}_{R} $ mass windows. All uncertainties are in number of events. In each table cell, the entry is of the form (mean $\pm $ stat. $\pm $ syst.). 
Summary 
In summary, a search for a righthanded W analogue to the W gauge boson in the decay channel of two leptons and two jets has been presented. No excess over standard model backgrounds are observed. A new W bosonlike particle, with standard model couplings, decaying via a new heavy neutrino, up to a mass of 4.4 TeV, is excluded at 95% confidence level by the data, providing the most stringent limits to date. 
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