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| CMS-PAS-SUS-19-005 | ||
| Searches for new phenomena in events with jets and high values of the $M_{\mathrm{T2}}$ variable, including signatures with disappearing tracks, in proton-proton collisions at $\sqrt{s}= $ 13 TeV | ||
| CMS Collaboration | ||
| March 2019 | ||
| Abstract: Searches for new phenomena are performed using events with jets and significant transverse momentum imbalance. In events with at least two jets, the transverse momentum imbalance is inferred through the $M_{\mathrm{T2}}$ variable. The results are based on a sample of proton-proton collisions collected with the CMS detector during the LHC Run II (2016-2018) and correspond to an integrated luminosity of 137 fb$^{-1}$ taken at a center-of-mass energy of 13 TeV. Two related searches are performed. The first is an inclusive search based on signal regions defined by the hadronic energy in the event, the jet multiplicity, the number of jets identified as originating from bottom quarks, and the value of $M_{\mathrm{T2}}$ for events with at least two jets, or the tranverse momentum of the jet for events with just one jet. The second is a search for disappearing tracks produced by new long-lived charged particles, decaying within the volume of the CMS tracking detector. No excess event yield is observed above the predicted standard model background, leading to exclusion limits on pair-produced gluinos and squarks in simplified models of $R$-parity conserving supersymmetry. Mass limits as high as 2250 GeV, 1770 GeV, 1260 GeV and 1225 GeV are obtained from the inclusive $M_{\mathrm{T2}}$ search for gluinos, light-flavor squarks, bottom squarks and top squarks, respectively. The search for disappearing tracks extends the gluino mass limit to as much as 2460 GeV, and the $\tilde{\chi}^{0}_{1}$ mass limit to as much as 2000 GeV, in models where the gluino can decay with equal probability to $\tilde{\chi}^{0}_{1}$, $\tilde{\chi}^{+}_{1}$, and $\tilde{\chi}^{-}_{1}$, and the $\tilde{\chi}^{\pm}_{1}$ are long-lived. | ||
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Links:
CDS record (PDF) ;
CADI line (restricted) ;
These preliminary results are superseded in this paper, EPJC 80 (2020) 3. The superseded preliminary plots can be found here. |
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| Figures | |
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Figure 1:
Distributions of the ${M_{\mathrm {T2}}}$ variable in data and simulation for the single-lepton control region selection, after normalizing the simulation to data in the control region bins of ${H_{\mathrm {T}}}$, ${N_{\mathrm {j}}}$, and ${N_{\mathrm{b}}}$ for events with no b-tagged jets (left), and events with at least one b-tagged jet (right). The hatched bands on the top panels show the MC statistical uncertainty, while the solid gray bands in the ratio plots show the systematic uncertainty in the ${M_{\mathrm {T2}}}$ shape. |
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Figure 1-a:
Distributions of the ${M_{\mathrm {T2}}}$ variable in data and simulation for the single-lepton control region selection, after normalizing the simulation to data in the control region bins of ${H_{\mathrm {T}}}$, ${N_{\mathrm {j}}}$, and ${N_{\mathrm{b}}}$ for events with no b-tagged jets. The hatched bands on the top panel show the MC statistical uncertainty, while the solid gray bands in the ratio plot shows the systematic uncertainty in the ${M_{\mathrm {T2}}}$ shape. |
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Figure 1-b:
Distributions of the ${M_{\mathrm {T2}}}$ variable in data and simulation for the single-lepton control region selection, after normalizing the simulation to data in the control region bins of ${H_{\mathrm {T}}}$, ${N_{\mathrm {j}}}$, and ${N_{\mathrm{b}}}$ for events with at least one b-tagged jet. The hatched bands on the top panel show the MC statistical uncertainty, while the solid gray bands in the ratio plot shows the systematic uncertainty in the ${M_{\mathrm {T2}}}$ shape. |
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Figure 2:
(Left) Ratio $R^{\mathrm {SF}/\mathrm {OF}}$ in data as a function of ${N_{\mathrm {j}}}$. The solid black line enclosed by the red dashed lines corresponds to a value of 1.07 $\pm$ 0.15 that is observed to be stable with respect to event kinematics, while the two dashed black lines denote the statistical uncertainty in the $R^{\mathrm {SF}/\mathrm {OF}}$ value. (Right) The shape of the ${M_{\mathrm {T2}}}$ distribution in $\mathrm{Z} \to \nu \bar{\nu} $ simulation compared to the one obtained from the $\mathrm{Z} \to \ell ^{+}\ell ^{-}$ data control sample, in a region with 1200 $ < {H_{\mathrm {T}}} < $ 1500 GeV and $ {N_{\mathrm {j}}} \geq $ 2, inclusive in ${N_{\mathrm{b}}}$. The solid gray band on the ratio plot shows the systematic uncertainty in the ${M_{\mathrm {T2}}}$ shape. |
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Figure 2-a:
Ratio $R^{\mathrm {SF}/\mathrm {OF}}$ in data as a function of ${N_{\mathrm {j}}}$. The solid black line enclosed by the red dashed lines corresponds to a value of 1.07 $\pm$ 0.15 that is observed to be stable with respect to event kinematics, while the two dashed black lines denote the statistical uncertainty in the $R^{\mathrm {SF}/\mathrm {OF}}$ value. |
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Figure 2-b:
The shape of the ${M_{\mathrm {T2}}}$ distribution in $\mathrm{Z} \to \nu \bar{\nu} $ simulation compared to the one obtained from the $\mathrm{Z} \to \ell ^{+}\ell ^{-}$ data control sample, in a region with 1200 $ < {H_{\mathrm {T}}} < $ 1500 GeV and $ {N_{\mathrm {j}}} \geq $ 2, inclusive in ${N_{\mathrm{b}}}$. The solid gray band on the ratio plot shows the systematic uncertainty in the ${M_{\mathrm {T2}}}$ shape. |
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Figure 3:
Validation of the R&S multijet background prediction, in control regions in data selected with $ {\Delta \phi _{\text {min}}} < $ 0.3. Electroweak backgrounds are estimated from data. In regions where statistics in data is insufficient to estimate the electroweak backgrounds, the corresponding yields are taken directly from simulation. Bins on the x-axis are the (${H_{\mathrm {T}}}$, $N_\text {jet}$, $N_\text {b-jet}$) topological regions. The gray band represents the total uncertainty on the prediction. |
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Figure 4:
Validation of the background prediction method in (upper) the 2016 data validation region, and in (lower) the 2017-2018 data validation region, in the search for disappearing tracks. The red histogram represents the predicted background, while the black points are the actual observed data counts. The cyan band represents the statistical uncertainty on the prediction. The gray band represents the total uncertainty. The labels on the $x$-axes are explained in Tables 7-8 of Appendix B.2. Regions whose predictions use the same measurement of $f_{\mathrm {short}}$ are identified by the colors of the labels. Bins with no entry in the ratio have zero predicted background. |
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Figure 4-a:
Validation of the background prediction method in the 2016 data validation region, in the search for disappearing tracks. The red histogram represents the predicted background, while the black points are the actual observed data counts. The cyan band represents the statistical uncertainty on the prediction. The gray band represents the total uncertainty. The labels on the $x$-axes are explained in Tables 7-8 of Appendix B.2. Regions whose predictions use the same measurement of $f_{\mathrm {short}}$ are identified by the colors of the labels. Bins with no entry in the ratio have zero predicted background. |
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Figure 4-b:
Validation of the background prediction method in the 2017-2018 data validation region, in the search for disappearing tracks. The red histogram represents the predicted background, while the black points are the actual observed data counts. The cyan band represents the statistical uncertainty on the prediction. The gray band represents the total uncertainty. The labels on the $x$-axes are explained in Tables 7-8 of Appendix B.2. Regions whose predictions use the same measurement of $f_{\mathrm {short}}$ are identified by the colors of the labels. Bins with no entry in the ratio have zero predicted background. |
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Figure 5:
(Upper) Comparison of estimated (pre-fit) background and observed data events in each topological region. Hatched bands represent the full uncertainty in the background estimate. The monojet regions ($ {N_{\mathrm {j}}} = $ 1) are identified by the labels "1j, 0b'' and "1j, 1b'', and are binned in jet ${p_{\mathrm {T}}}$. The multijet ones are shown for each ${H_{\mathrm {T}}}$ region separately, and are labeled accordingly. The notations j, b indicate ${N_{\mathrm {j}}}$, ${N_{\mathrm{b}}}$ labeling. (Lower) Same for individual ${M_{\mathrm {T2}}}$ signal bins in the medium ${H_{\mathrm {T}}}$ region. On the $x$-axis, the ${M_{\mathrm {T2}}}$ binning is shown in units of GeV. |
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Figure 5-a:
Comparison of estimated (pre-fit) background and observed data events in each topological region. Hatched bands represent the full uncertainty in the background estimate. The monojet regions ($ {N_{\mathrm {j}}} = $ 1) are identified by the labels "1j, 0b'' and "1j, 1b'', and are binned in jet ${p_{\mathrm {T}}}$. The multijet ones are shown for each ${H_{\mathrm {T}}}$ region separately, and are labeled accordingly. The notations j, b indicate ${N_{\mathrm {j}}}$, ${N_{\mathrm{b}}}$ labeling. |
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Figure 5-b:
Same for individual ${M_{\mathrm {T2}}}$ signal bins in the medium ${H_{\mathrm {T}}}$ region. On the $x$-axis, the ${M_{\mathrm {T2}}}$ binning is shown in units of GeV. |
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Figure 6:
Comparison of estimated (pre-fit) background and observed data events in (upper) each of the 2016 search regions, and in (lower) each of the 2017-2018 search regions, in the search for disappearing tracks. The red histogram represents the predicted background, while the black points are the actual observed data counts. The cyan band represents the statistical uncertainty on the prediction. The gray band represents the total uncertainty. The labels on the $x$-axes are explained in Tables 7-8 of Appendix B.2. Regions whose predictions use the same measurement of $f_{\mathrm {short}}$ are identified by the colors of the labels. Bins with no entry in the ratio have zero (pre-fit) predicted background. |
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Figure 6-a:
Comparison of estimated (pre-fit) background and observed data events in each of the 2016 search regions, in the search for disappearing tracks. The red histogram represents the predicted background, while the black points are the actual observed data counts. The cyan band represents the statistical uncertainty on the prediction. The gray band represents the total uncertainty. The labels on the $x$-axes are explained in Tables 7-8 of Appendix B.2. Regions whose predictions use the same measurement of $f_{\mathrm {short}}$ are identified by the colors of the labels. Bins with no entry in the ratio have zero (pre-fit) predicted background. |
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Figure 6-b:
Comparison of estimated (pre-fit) background and observed data events in each of the 2017-2018 search regions, in the search for disappearing tracks. The red histogram represents the predicted background, while the black points are the actual observed data counts. The cyan band represents the statistical uncertainty on the prediction. The gray band represents the total uncertainty. The labels on the $x$-axes are explained in Tables 7-8 of Appendix B.2. Regions whose predictions use the same measurement of $f_{\mathrm {short}}$ are identified by the colors of the labels. Bins with no entry in the ratio have zero (pre-fit) predicted background. |
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Figure 7:
(Upper) Diagrams for the three scenarios of gluino-mediated light-flavor squark, bottom squark and top squark production considered. (Lower) Diagrams for the direct production of light-flavor, bottom and top squark pairs. |
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Figure 7-a:
Diagram for the gluino-mediated light-flavor squark, bottom squark and top squark production. |
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Figure 7-b:
Diagram for the gluino-mediated light-flavor squark, bottom squark and top squark production. |
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Figure 7-c:
Diagram for the gluino-mediated light-flavor squark, bottom squark and top squark production. |
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Figure 7-d:
Diagram for the direct production of light-flavor, bottom and top squark pairs. |
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Figure 7-e:
Diagram for the direct production of light-flavor, bottom and top squark pairs. |
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Figure 7-f:
Diagram for the direct production of light-flavor, bottom and top squark pairs. |
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Figure 8:
Diagram showing the decays of a gluino via a long-lived ${\tilde{\chi}^{\pm}_{1}}$. The mass of the ${\tilde{\chi}^{\pm}_{1}}$ is larger than the mass of the $\tilde{\chi}^0_1$ by few hundred MeV. The ${\tilde{\chi}^{\pm}_{1}}$ decays to a $\tilde{\chi}^0_1$ via a pion, too soft to be detected. |
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Figure 9:
Exclusion limits at 95% CL for gluino-mediated light-flavor (u, d, s, c) squark production (above left), gluino-mediated bottom squark production (above right), and gluino-mediated top squark production (below). The area enclosed by the thick black curve represents the observed exclusion region, while the dashed red lines indicate the expected limits and their $\pm $1 standard deviation ranges. The thin black lines show the effect of the theoretical uncertainties on the signal cross section. |
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Figure 9-a:
Exclusion limits at 95% CL for gluino-mediated light-flavor (u, d, s, c) squark production. The area enclosed by the thick black curve represents the observed exclusion region, while the dashed red lines indicate the expected limits and their $\pm $1 standard deviation ranges. The thin black lines show the effect of the theoretical uncertainties on the signal cross section. |
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Figure 9-b:
Exclusion limits at 95% CL for gluino-mediated bottom squark production. The area enclosed by the thick black curve represents the observed exclusion region, while the dashed red lines indicate the expected limits and their $\pm $1 standard deviation ranges. The thin black lines show the effect of the theoretical uncertainties on the signal cross section. |
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Figure 9-c:
Exclusion limits at 95% CL for gluino-mediated top squark production. The area enclosed by the thick black curve represents the observed exclusion region, while the dashed red lines indicate the expected limits and their $\pm $1 standard deviation ranges. The thin black lines show the effect of the theoretical uncertainties on the signal cross section. |
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Figure 10:
Exclusion limit at 95% CL for light-flavor squark pair production (above left), bottom squark pair production (above right), and top squark pair production (below). The area enclosed by the thick black curve represents the observed exclusion region, while the dashed red lines indicate the expected limits and their $\pm $1 and $\pm $2 standard deviation ranges. The thin black lines show the effect of the theoretical uncertainties on the signal cross section. The white diagonal band in the top squark pair production exclusion limit corresponds to the region $ {| m_{\tilde{\mathrm{t}}}-m_{\mathrm{t}}-m_{\tilde{\chi}^0_1} |} < $ 25 GeV and small $m_{\tilde{\chi}^0_1}$. Here the efficiency of the selection is a strong function of $m_{\tilde{\mathrm{t}}}-m_{\tilde{\chi}^0_1}$, and as a result the precise determination of the cross section upper limit is uncertain because of the finite granularity of the available MC samples in this region of the ($m_{\tilde{\mathrm{t}}}, m_{\tilde{\chi}^0_1}$) plane. |
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Figure 10-a:
Exclusion limit at 95% CL for light-flavor squark pair production. The area enclosed by the thick black curve represents the observed exclusion region, while the dashed red lines indicate the expected limits and their $\pm $1 and $\pm $2 standard deviation ranges. The thin black lines show the effect of the theoretical uncertainties on the signal cross section. |
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Figure 10-b:
Exclusion limit at 95% CL for bottom squark pair production. The area enclosed by the thick black curve represents the observed exclusion region, while the dashed red lines indicate the expected limits and their $\pm $1 and $\pm $2 standard deviation ranges. The thin black lines show the effect of the theoretical uncertainties on the signal cross section. |
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Figure 10-c:
Exclusion limit at 95% CL for top squark pair production. The area enclosed by the thick black curve represents the observed exclusion region, while the dashed red lines indicate the expected limits and their $\pm $1 and $\pm $2 standard deviation ranges. The thin black lines show the effect of the theoretical uncertainties on the signal cross section. The white diagonal band corresponds to the region $ {| m_{\tilde{\mathrm{t}}}-m_{\mathrm{t}}-m_{\tilde{\chi}^0_1} |} < $ 25 GeV and small $m_{\tilde{\chi}^0_1}$. Here the efficiency of the selection is a strong function of $m_{\tilde{\mathrm{t}}}-m_{\tilde{\chi}^0_1}$, and as a result the precise determination of the cross section upper limit is uncertain because of the finite granularity of the available MC samples in this region of the ($m_{\tilde{\mathrm{t}}}, m_{\tilde{\chi}^0_1}$) plane. |
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Figure 11:
Exclusion limits at 95% CL for gluino-mediated light-flavor (u, d, s, c) squark production with $c\tau _{0}({\tilde{\chi}^{\pm}_{1}}) =$ 10 cm (above left), 50 cm (above right), and 200 cm (below). The area enclosed by the thick black curve represents the observed exclusion region, while the dashed red lines indicate the expected limits and their $\pm $1 standard deviation ranges. The thin black lines show the effect of the theoretical uncertainties on the signal cross section. The white band for masses of the $\tilde{\chi}^0_1$ below 91.9 GeV represent the region of the mass plane excluded at LEP [65]. |
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Figure 11-a:
Exclusion limits at 95% CL for gluino-mediated light-flavor (u, d, s, c) squark production with $c\tau _{0}({\tilde{\chi}^{\pm}_{1}}) =$ 10 cm. The area enclosed by the thick black curve represents the observed exclusion region, while the dashed red lines indicate the expected limits and their $\pm $1 standard deviation ranges. The thin black lines show the effect of the theoretical uncertainties on the signal cross section. The white band for masses of the $\tilde{\chi}^0_1$ below 91.9 GeV represent the region of the mass plane excluded at LEP [65]. |
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Figure 11-b:
Exclusion limits at 95% CL for gluino-mediated light-flavor (u, d, s, c) squark production with $c\tau _{0}({\tilde{\chi}^{\pm}_{1}}) =$ 50 cm. The area enclosed by the thick black curve represents the observed exclusion region, while the dashed red lines indicate the expected limits and their $\pm $1 standard deviation ranges. The thin black lines show the effect of the theoretical uncertainties on the signal cross section. The white band for masses of the $\tilde{\chi}^0_1$ below 91.9 GeV represent the region of the mass plane excluded at LEP [65]. |
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Figure 11-c:
Exclusion limits at 95% CL for gluino-mediated light-flavor (u, d, s, c) squark production with $c\tau _{0}({\tilde{\chi}^{\pm}_{1}}) =$ 200 cm. The area enclosed by the thick black curve represents the observed exclusion region, while the dashed red lines indicate the expected limits and their $\pm $1 standard deviation ranges. The thin black lines show the effect of the theoretical uncertainties on the signal cross section. The white band for masses of the $\tilde{\chi}^0_1$ below 91.9 GeV represent the region of the mass plane excluded at LEP [65]. |
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Figure 12:
(Upper) Comparison of the estimated background and observed data events in each signal bin in the monojet region. On the $x$-axis, the ${{p_{\mathrm {T}}} ^{\text {jet1}}}$ binning is shown in units of GeV. Hatched bands represent the full uncertainty in the background estimate. The notations j, b indicate ${N_{\mathrm {j}}}$, ${N_{\mathrm{b}}}$ labeling. (Lower) Same for the very low ${H_{\mathrm {T}}}$ region. On the $x$-axis, the ${M_{\mathrm {T2}}}$ binning is shown in units of GeV. |
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Figure 12-a:
Comparison of the estimated background and observed data events in each signal bin in the monojet region. On the $x$-axis, the ${{p_{\mathrm {T}}} ^{\text {jet1}}}$ binning is shown in units of GeV. Hatched bands represent the full uncertainty in the background estimate. The notations j, b indicate ${N_{\mathrm {j}}}$, ${N_{\mathrm{b}}}$ labeling. |
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Figure 12-b:
Same for the very low ${H_{\mathrm {T}}}$ region. On the $x$-axis, the ${M_{\mathrm {T2}}}$ binning is shown in units of GeV. |
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Figure 13:
(Upper) Comparison of the estimated background and observed data events in each signal bin in the low-${H_{\mathrm {T}}}$ region. Hatched bands represent the full uncertainty in the background estimate. The notations j, b indicate ${N_{\mathrm {j}}}$, ${N_{\mathrm{b}}}$ labeling. Same for the high- (middle) and extreme- (lower) ${H_{\mathrm {T}}}$ regions. On the $x$-axis, the ${M_{\mathrm {T2}}}$ binning is shown in units of GeV. |
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Figure 13-a:
(Upper) Comparison of the estimated background and observed data events in each signal bin in the low-${H_{\mathrm {T}}}$ region. Hatched bands represent the full uncertainty in the background estimate. The notations j, b indicate ${N_{\mathrm {j}}}$, ${N_{\mathrm{b}}}$ labeling. Same for the high- (middle) and extreme- (lower) ${H_{\mathrm {T}}}$ regions. On the $x$-axis, the ${M_{\mathrm {T2}}}$ binning is shown in units of GeV. |
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Figure 13-b:
(Upper) Comparison of the estimated background and observed data events in each signal bin in the low-${H_{\mathrm {T}}}$ region. Hatched bands represent the full uncertainty in the background estimate. The notations j, b indicate ${N_{\mathrm {j}}}$, ${N_{\mathrm{b}}}$ labeling. Same for the high- (middle) and extreme- (lower) ${H_{\mathrm {T}}}$ regions. On the $x$-axis, the ${M_{\mathrm {T2}}}$ binning is shown in units of GeV. |
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Figure 13-c:
(Upper) Comparison of the estimated background and observed data events in each signal bin in the low-${H_{\mathrm {T}}}$ region. Hatched bands represent the full uncertainty in the background estimate. The notations j, b indicate ${N_{\mathrm {j}}}$, ${N_{\mathrm{b}}}$ labeling. Same for the high- (middle) and extreme- (lower) ${H_{\mathrm {T}}}$ regions. On the $x$-axis, the ${M_{\mathrm {T2}}}$ binning is shown in units of GeV. |
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Figure 14:
(Upper) Comparison of the post-fit estimated background and observed data events in each signal bin in the monojet region. On the $x$-axis, the ${{p_{\mathrm {T}}} ^{\text {jet1}}}$ binning is shown in units of GeV. Hatched bands represent the full uncertainty in the background estimate. The notations j, b indicate ${N_{\mathrm {j}}}$, ${N_{\mathrm{b}}}$ labeling. (Lower) Same for the very low-${H_{\mathrm {T}}}$ region. On the $x$-axis, the ${M_{\mathrm {T2}}}$ binning is shown in units of GeV. |
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Figure 14-a:
Comparison of the post-fit estimated background and observed data events in each signal bin in the monojet region. On the $x$-axis, the ${{p_{\mathrm {T}}} ^{\text {jet1}}}$ binning is shown in units of GeV. Hatched bands represent the full uncertainty in the background estimate. The notations j, b indicate ${N_{\mathrm {j}}}$, ${N_{\mathrm{b}}}$ labeling. |
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Figure 14-b:
Same for the very low-${H_{\mathrm {T}}}$ region. On the $x$-axis, the ${M_{\mathrm {T2}}}$ binning is shown in units of GeV. |
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Figure 15:
(Upper) Comparison of the post-fit estimated background and observed data events in each signal bin in the low-${H_{\mathrm {T}}}$ region. Hatched bands represent the full uncertainty in the background estimate. The notations j, b indicate ${N_{\mathrm {j}}}$, ${N_{\mathrm{b}}}$ labeling. (Lower) Same for the medium-${H_{\mathrm {T}}}$ region. On the $x$-axis, the ${M_{\mathrm {T2}}}$ binning is shown in units of GeV. |
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Figure 15-a:
Comparison of the post-fit estimated background and observed data events in each signal bin in the low-${H_{\mathrm {T}}}$ region. Hatched bands represent the full uncertainty in the background estimate. The notations j, b indicate ${N_{\mathrm {j}}}$, ${N_{\mathrm{b}}}$ labeling. |
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Figure 15-b:
Same for the medium-${H_{\mathrm {T}}}$ region. On the $x$-axis, the ${M_{\mathrm {T2}}}$ binning is shown in units of GeV. |
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Figure 16:
(Upper) Comparison of the post-fit estimated background and observed data events in each signal bin in the high-${H_{\mathrm {T}}}$ region. Hatched bands represent the full uncertainty in the background estimate. The notations j, b indicate ${N_{\mathrm {j}}}$, ${N_{\mathrm{b}}}$ labeling. (Lower) Same for the extreme-${H_{\mathrm {T}}}$ region. On the $x$-axis, the ${M_{\mathrm {T2}}}$ binning is shown in units of GeV. |
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Figure 16-a:
Comparison of the post-fit estimated background and observed data events in each signal bin in the high-${H_{\mathrm {T}}}$ region. Hatched bands represent the full uncertainty in the background estimate. The notations j, b indicate ${N_{\mathrm {j}}}$, ${N_{\mathrm{b}}}$ labeling. |
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Figure 16-b:
Same for the extreme-${H_{\mathrm {T}}}$ region. On the $x$-axis, the ${M_{\mathrm {T2}}}$ binning is shown in units of GeV. |
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Figure 17:
Background prediction (post-fit) and observation in the 2016 data signal region, in the full analysis binning of the search for disappearing tracks. The blue histogram represents the predicted (post-fit) background, while the black points are the actual observed data counts. The blue band represents the uncertainty on the prediction. The labels on the $x$-axes are explained in Tables 7-8 of Appendix B.2. Regions whose predictions use the same measurement of $f_{\mathrm {short}}$ are identified by the colors of the labels. |
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Figure 18:
Background prediction (post-fit) and observation in the 2017-2018 data signal region, in the full analysis binning of the search for disappearing tracks. The blue histogram represents the predicted (post-fit) background, while the black points are the actual observed data counts. The blue band represents the uncertainty on the prediction. The labels on the $x$-axes are explained in Tables 7-8 of Appendix B.2. Regions whose predictions use the same measurement of $f_{\mathrm {short}}$ are identified by the colors of the labels. |
| Tables | |
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Table 1:
Summary of the trigger requirements and the kinematic offline event preselection requirements on the reconstructed physics objects, for both the inclusive ${M_{\mathrm {T2}}}$ search and the search for disappearing tracks. Here $R$ is the distance parameter of the anti-$ {k_{\mathrm {T}}}$ algorithm. For veto leptons and tracks, the transverse mass ${M_{\mathrm {T}}}$ is determined using the veto object and the $\vec{p}_{\mathrm{T}}^{\text{miss}}$. The variable $ {p_{\mathrm {T}}} ^{\text {sum}}$ is a measure of isolation and it denotes the sum of the transverse momenta of all the PF candidates in a cone around the lepton or the track. The size of the cone, in units of $\Delta R \equiv \sqrt {\smash [b]{(\Delta \phi)^2 + (\Delta \eta)^2}}$ is given in the table. Further details of the lepton selection are described in Refs. [2,3]. The $i$th highest-$ {p_{\mathrm {T}}} $ jet is denoted as j$_i$. |
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Table 2:
Typical values of the systematic uncertainties as evaluated for the simplified models of SUSY used in the context of this search. The high statistical uncertainty in the simulated signal sample corresponds to a small number of signal bins with low acceptance, which are typically not among the most sensitive signal bins to that model point. |
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Table 3:
Selection requirements for short tracks (ST) and short track candidates (STC). For the subset of medium length (M) tracks that have just four tracking layers with a measurement, the minimum required number of layers of the pixel tracking detector with a measurement is three ($\dagger $). The selected tracks are required to not overlap with identified leptons. For this selection, all electrons and muons are considered, either identified as PF candidates or not. The selected tracks are as well required to not be identified as PF candidates. The factor by which the selection requirement is relaxed in order to select short track candidates is also reported. If no factor is reported, the requirement is not relaxed for the selection of short track candidates. |
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Table 4:
Summary of signal regions for the monojet selection. |
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Table 5:
The ${M_{\mathrm {T2}}}$ binning in each topological region of the multi-jet search regions, for the very low, low and medium ${H_{\mathrm {T}}}$ regions. |
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Table 6:
The ${M_{\mathrm {T2}}}$ binning in each topological region of the multi-jet search regions, for the high and extreme ${H_{\mathrm {T}}}$ regions. |
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Table 7:
Summary of the signal regions of the search for disappearing tracks, for the 2016 data set. |
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Table 8:
Summary of the signal regions of the search for disappearing tracks, for the 2017-2018 data set. |
| Summary |
| This note presents the results of two related searches for new phenomena using events with jets and large ${M_{\mathrm{T2}}}$. Results are based on a 137 fb$^{-1}$ data sample of proton-proton collisions at $\sqrt{s} = $ 13 TeV collected in 2016, 2017 and 2018 with the CMS detector. No significant deviations from the standard model expectations are observed. The results are interpreted as limits on pair-produced gluinos and squarks in simplified models of $R$-parity conserving supersymmetry. The inclusive ${M_{\mathrm{T2}}}$ search probes gluino masses up to 2250 GeV and $\tilde{\chi}^0_1$ masses up to 1525 GeV, as well as light-flavor, bottom, and top squark masses up to 1770, 1260, and 1225 GeV, respectively, and $\tilde{\chi}^0_1$ masses up to 975, 725, and 600 GeV in each scenario. The search for disappearing tracks extends the gluino mass limit to as much as 2460 GeV, and the $\tilde{\chi}^0_1$ mass limit to as much as 2000 GeV, in models where the gluino can decay with equal probability to $\tilde{\chi}^0_1$, ${\tilde{\chi}^{+}_{1}} $, and ${\tilde{\chi}^{-}_{1}} $, and the ${\tilde{\chi}^{\pm}_{1}}$ are long-lived. |
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