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| CMS-PAS-EXO-17-030 | ||
| Search for pair-produced three-jet resonances in proton-proton collisions at $\sqrt{s}= $ 13 TeV | ||
| CMS Collaboration | ||
| July 2018 | ||
| Abstract: A search for three-jet hadronic resonance production in pp collisions at a center-of-mass energy of 13 TeV has been conducted by the CMS Collaboration at the LHC with a data sample corresponding to an integrated luminosity of 35.9 fb$^{-1}$. This resonance search in events with high jet multiplicity is largely model independent, although an R-parity-violating supersymmetric model of gluino pair production which results in a six-jet final state is used to optimize the event selection. The search is optimized separately for four mass ranges from 200 GeV to 2000 GeV, with significant improvements in sensitivity compared to previous analyses, especially at low masses. Good agreement is observed between data and expected standard model and $\mathrm{t\bar{t}}$ backgrounds. The resulting upper limits on pair-produced three-jet resonances are the most stringent to date. | ||
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Links:
CDS record (PDF) ;
inSPIRE record ;
CADI line (restricted) ;
These preliminary results are superseded in this paper, PRD 99 (2019) 012010. The superseded preliminary plots can be found here. |
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| Figures | |
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Figure 1:
Pair masses within the triplet as described in Eq. 1 plotted $\hat{m}(3,2)^2_{high}$ vs. $\hat{m}(3,2)^2_{low}$, $\hat{m}(3,2)^2_{high}$ vs. $\hat{m}(3,2)^2_{mid}$ and $\hat{m}(3,2)^2_{mid}$ vs. $\hat{m}(3,2)^2_{low}$. QCD triplets (left) cluster at the edge, while triplets from signal events ($m_{\tilde{g}} = $ 800 GeV, right) fill the center. |
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Figure 1-a:
Pair masses within the triplet as described in Eq. 1 plotted $\hat{m}(3,2)^2_{high}$ vs. $\hat{m}(3,2)^2_{low}$, $\hat{m}(3,2)^2_{high}$ vs. $\hat{m}(3,2)^2_{mid}$ and $\hat{m}(3,2)^2_{mid}$ vs. $\hat{m}(3,2)^2_{low}$. QCD triplets (left) cluster at the edge, while triplets from signal events ($m_{\tilde{g}} = $ 800 GeV, right) fill the center. |
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Figure 1-b:
Pair masses within the triplet as described in Eq. 1 plotted $\hat{m}(3,2)^2_{high}$ vs. $\hat{m}(3,2)^2_{low}$, $\hat{m}(3,2)^2_{high}$ vs. $\hat{m}(3,2)^2_{mid}$ and $\hat{m}(3,2)^2_{mid}$ vs. $\hat{m}(3,2)^2_{low}$. QCD triplets (left) cluster at the edge, while triplets from signal events ($m_{\tilde{g}} = $ 800 GeV, right) fill the center. |
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Figure 2:
On left, MDS[(6,3)+(3,2)] as described in Eq. xxxxx, for signal (RPV gluino of mass 400 GeV) and QCD triplets. On right, MDS[3,2] variable as described in Eq. 2 for signal (RPV gluino of mass 400 GeV) and QCD triplets. The distributions are made after nominal selection criteria. |
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Figure 2-a:
On left, MDS[(6,3)+(3,2)] as described in Eq. xxxxx, for signal (RPV gluino of mass 400 GeV) and QCD triplets. On right, MDS[3,2] variable as described in Eq. 2 for signal (RPV gluino of mass 400 GeV) and QCD triplets. The distributions are made after nominal selection criteria. |
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Figure 2-b:
On left, MDS[(6,3)+(3,2)] as described in Eq. xxxxx, for signal (RPV gluino of mass 400 GeV) and QCD triplets. On right, MDS[3,2] variable as described in Eq. 2 for signal (RPV gluino of mass 400 GeV) and QCD triplets. The distributions are made after nominal selection criteria. |
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Figure 3:
The triplet invariant mass versus the triplet scalar ${p_{\mathrm {T}}}$ for a gluino of mass 400 GeV decaying to jets. The filled color represents correctly reconstructed signal triplets, while the contour lines and gray scatter points represent wrongly combined triplets. The red line illustrates the $\Delta $ cut; triplets to the right of the line pass the selection criterion. |
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Figure 4:
Mass distributions and background-only fits for the first two mass regions. Region 1 (left) is fit to the blackbody-like function described in Eq. 7 as well as ${{\mathrm {t}\overline {\mathrm {t}}}}$ simulation, while the Region 2 (right) are fit to the four parameter function from Eq. 8. The vertical gray lines indicate the mass regions. The gluino signal normalized to the cross section expected from [29] is shown in orange. |
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Figure 4-a:
Mass distributions and background-only fits for the first two mass regions. Region 1 (left) is fit to the blackbody-like function described in Eq. 7 as well as ${{\mathrm {t}\overline {\mathrm {t}}}}$ simulation, while the Region 2 (right) are fit to the four parameter function from Eq. 8. The vertical gray lines indicate the mass regions. The gluino signal normalized to the cross section expected from [29] is shown in orange. |
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Figure 4-b:
Mass distributions and background-only fits for the first two mass regions. Region 1 (left) is fit to the blackbody-like function described in Eq. 7 as well as ${{\mathrm {t}\overline {\mathrm {t}}}}$ simulation, while the Region 2 (right) are fit to the four parameter function from Eq. 8. The vertical gray lines indicate the mass regions. The gluino signal normalized to the cross section expected from [29] is shown in orange. |
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Figure 5:
Mass distributions and background-only fits for the last two mass regions. Region 3 (left) is fit to the four parameter function from Eq. 8, while the Region 4 (right) is fit to three parameter function from Eq 8 with $p_3=$ 0. The vertical gray lines indicate the mass regions. The gluino signal normalized to the cross section expected from [29] is shown in orange. |
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Figure 5-a:
Mass distributions and background-only fits for the last two mass regions. Region 3 (left) is fit to the four parameter function from Eq. 8, while the Region 4 (right) is fit to three parameter function from Eq 8 with $p_3=$ 0. The vertical gray lines indicate the mass regions. The gluino signal normalized to the cross section expected from [29] is shown in orange. |
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Figure 5-b:
Mass distributions and background-only fits for the last two mass regions. Region 3 (left) is fit to the four parameter function from Eq. 8, while the Region 4 (right) is fit to three parameter function from Eq 8 with $p_3=$ 0. The vertical gray lines indicate the mass regions. The gluino signal normalized to the cross section expected from [29] is shown in orange. |
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Figure 6:
Observed and expected frequentist CLs cross section limits are calculated in the asymptotic approximation. The solid red line shows the predictions for the gluino pair productions from [29]. The band around theory curve describes the uncertainties from parton distribution function and scale choices. The gray vertical lines indicate the boundaries between the mass regions. |
| Tables | |
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Table caption text:
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Table 2:
Summary of the systematic uncertainties. For the shape uncertainties, the value represents the percentage difference in the nominal value of the systematic uncertainty. These systematic uncertainties are applied to the signal. |
| Summary |
| We have performed an inclusive search for pair-produced three jet resonances. The proton-proton collision data used for this analysis was collected with the CMS detector in 2016 with a center of mass energy of $\sqrt{s}=$ 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. We explore the mass range from 200 GeV to 2000 GeV in four separate mass regions. Our observations show agreement with standard model expectations. The result is interpreted within the framework of RPV SUSY, where pair-produced gluinos decay to a six quark final state. We exclude gluino masses below 1500 GeV at 95% confidence level. Analysis based on data with multijet events reconstructed at the trigger level allowed us extend our reach to masses as low as 200 GeV. Improved analysis techniques led to enhanced sensitivity and allowed us to set the most stringent limits on RPV gluino pair production. |
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