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| CMS-PAS-SUS-15-003 | ||
| Search for new physics in the all-hadronic final state with the $M_{\mathrm{T2}}$ variable | ||
| CMS Collaboration | ||
| December 2015 | ||
| Abstract: A search for new physics is performed using events with jets and the $M_{\mathrm{T2}}$ variable, which is a measure of the transverse momentum imbalance in an event. Results are based on a sample of proton-proton collisions collected at a center-of-mass energy of 13 TeV with the CMS detector and corresponding to an integrated luminosity of 2.2 fb$^{-1}$. No excess above the standard model background is observed. The results are interpreted as limits on the masses of potential new colored particles in a variety of simplified models of supersymmetry. | ||
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Links:
CDS record (PDF) ;
CADI line (restricted) ;
These preliminary results are superseded in this paper, JHEP 10 (2016) 006. |
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| Figures | |
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Figure 1-a:
Shape comparison between simulation and data for the $ M_{\mathrm{T2}} $ observable. The left and right panels correspond to W+jets and $ \mathrm{ t \overline {t} }$+jets enriched control samples, respectively. |
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Figure 1-b:
Shape comparison between simulation and data for the $ M_{\mathrm{T2}} $ observable. The left and right panels correspond to W+jets and $ \mathrm{ t \overline {t} }$+jets enriched control samples, respectively. |
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Figure 2-a:
The (a) plot shows the photon purity measured in data for the single photon control sample compared with the values extracted from simulation. The (b) plot shows $R(Z/\gamma )$ the $Z/\gamma $ ratio in simulation and data as a function of $ {H_{\mathrm {T}}} $, and the corresponding double ratio (bottom panel). |
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Figure 2-b:
The (a) plot shows the photon purity measured in data for the single photon control sample compared with the values extracted from simulation. The (b) plot shows $R(Z/\gamma )$ the $Z/\gamma $ ratio in simulation and data as a function of $ {H_{\mathrm {T}}} $, and the corresponding double ratio (bottom panel). |
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Figure 3-a:
The shape of the $ M_{\mathrm{T2}} $ distribution from $ \mathrm{Z} \rightarrow \nu \overline {\nu } $ simulation compared to shapes extracted from $\gamma $ and $W$ data control samples in the medium $ {H_{\mathrm {T}}} $ and high $ {H_{\mathrm {T}}} $ regions. |
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Figure 3-b:
The shape of the $ M_{\mathrm{T2}} $ distribution from $ \mathrm{Z} \rightarrow \nu \overline {\nu } $ simulation compared to shapes extracted from $\gamma $ and $W$ data control samples in the medium $ {H_{\mathrm {T}}} $ and high $ {H_{\mathrm {T}}} $ regions. |
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Figure 4:
Distribution of the ratio $r_{\phi }$ as a function of $ M_{\mathrm{T2}} $ for the high $ H_{\mathrm{T}} $ region. The fit is performed to the hollow, background-subtracted data points. The full points represent the data before subtracting non-QCD backgrounds using simulation. Data point uncertainties are statistical only. The red line and the band around it show the fit to a power-law function perfomed in the window 70 $< M_{\mathrm{T2}} <$ 100 GeV and the associated fit uncertainty. |
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Figure 5-a:
Values of $f_j$ (a) and $r_b$ (b) measured in data after requiring $ {\Delta \phi _{\mathrm {min}}} <$ 0.3 radians and 100 $< M_{\mathrm{T2}} <$ 200 GeV. The bands represent both statistical and systematic uncertainties. |
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Figure 5-b:
Values of $f_j$ (a) and $r_b$ (b) measured in data after requiring $ {\Delta \phi _{\mathrm {min}}} <$ 0.3 radians and 100 $< M_{\mathrm{T2}} <$ 200 GeV. The bands represent both statistical and systematic uncertainties. |
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Figure 6:
Comparison of the data-driven predictions of the multi-jet background in the toppological regions ($ M_{\mathrm{T2}} >$ 200 GeV) from the R\&S method and the $ {\Delta \phi _{\mathrm {min}}} $-ratio method. The uncertainties are statistical and systematic. Within each of the four $ H_{\mathrm{T}} $ categories, all the estimates from the $ {\Delta \phi _{\mathrm {min}}} $-ratio method are correlated because they are derived from the same fit to the $ {\Delta \phi _{\mathrm {min}}} $-ratio data. |
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Figure 7-a:
(a) Comparison of estimated background and observed data events in each topological region. Hatched bands represent the full uncertainty on the background estimate. (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 GeV). Bins with no entry for data have an observed count of 0. |
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Figure 7-b:
(a) Comparison of estimated background and observed data events in each topological region. Hatched bands represent the full uncertainty on the background estimate. (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 GeV). Bins with no entry for data have an observed count of 0. |
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Figure 8-a:
Diagrams for the three scenarios of gluino mediated bottom squark, top squark and light flavor squark production considered. |
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Figure 8-b:
Diagrams for the three scenarios of gluino mediated bottom squark, top squark and light flavor squark production considered. |
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Figure 8-c:
Diagrams for the three scenarios of gluino mediated bottom squark, top squark and light flavor squark production considered. |
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Figure 9:
Exclusion limit at 95% CL for gluino mediated bottom-squark production. The area to the left of and below the thick black curve represents the observed exclusion region, while the dashed red lines indicate the expected limit and $\pm $1 standard-deviation. The thin black lines show the effect of the theoretical cross section uncertainties. |
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Figure 10:
Exclusion limit at 95% CL for gluino mediated top-squark production. The area to the left of and below the thick black curve represents the observed exclusion region, while the dashed red lines indicate the expected limit and $\pm $1 standard-deviation. The thin black lines show the effect of the theoretical cross section uncertainties. |
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Figure 11:
Exclusion limit at 95% CL for gluino mediated squark production, where the squark can be any of the first two generations. The area to the left of and below the thick black curve represents the observed exclusion region, while the dashed red lines indicate the expected limit and $\pm $1 standard-deviation. The thin black lines show the effect of the theoretical cross section uncertainties. |
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Figure 12-a:
(a) Comparison of the estimated background and observed data events in each signal bin in the mono-jet region. On the $x$-axis, the $ H_{\mathrm{T}} $ binning is shown (in GeV). Hatched bands represent the full uncertainty on the background estimate. (Below) Same for the very low $ H_{\mathrm{T}} $ region. On the $x$-axis, the $ M_{\mathrm{T2}} $ binning is shown (in GeV). Bins with no entry for data have an observed count of 0. |
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Figure 12-b:
(a) Comparison of the estimated background and observed data events in each signal bin in the mono-jet region. On the $x$-axis, the $ H_{\mathrm{T}} $ binning is shown (in GeV). Hatched bands represent the full uncertainty on the background estimate. (Below) Same for the very low $ H_{\mathrm{T}} $ region. On the $x$-axis, the $ M_{\mathrm{T2}} $ binning is shown (in GeV). Bins with no entry for data have an observed count of 0. |
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Figure 13-a:
(a) 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 on the background estimate. Same for the high (middle) and extreme (b) $ H_{\mathrm{T}} $ regions. On the $x$-axis, the $ M_{\mathrm{T2}} $ binning is shown (in GeV). Bins with no entry for data have an observed count of 0. |
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Figure 13-b:
(a) 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 on the background estimate. Same for the high (middle) and extreme (b) $ H_{\mathrm{T}} $ regions. On the $x$-axis, the $ M_{\mathrm{T2}} $ binning is shown (in GeV). Bins with no entry for data have an observed count of 0. |
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Figure 13-c:
(a) 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 on the background estimate. Same for the high (middle) and extreme (b) $ H_{\mathrm{T}} $ regions. On the $x$-axis, the $ M_{\mathrm{T2}} $ binning is shown (in GeV). Bins with no entry for data have an observed count of 0. |
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Figure 14:
Comparison of post-fit background prediction and observed data events in each topological region. Hatched bands represent the post-fit uncertainty on the background prediction. For the monojet, on the $x$-axis the $ H_{\mathrm{T}} $ binning is shown (in GeV). |
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Figure 15:
Post-fit background prediction, expected signal yields and observed data events in each topological region. Hatched bands represent the post-fit uncertainty on the background prediction. For the monojet, on the $x$-axis the $ H_{\mathrm{T}} $ binning is shown (in GeV). The compressed-spectra signal model considered here is gluino-mediated bottom-squark production with mass of the gluino and LSP equal to 700 and 600 GeV, respectively. |
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Figure 16:
Post-fit background prediction, expected signal yields and observed data events in each signal bin in the extreme $ H_{\mathrm{T}} $ region. Hatched bands represent the post-fit uncertainty on the background prediction. On the $x$-axis the $ M_{\mathrm{T2}} $ binning is shown (in GeV). The open-spectra signal model considered here is gluino-mediated bottom-squark production with mass of the gluino and LSP equal to 1500 and 100 GeV, respectively. |
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