CMS-PAS-SUS-16-016 | ||
An inclusive search for new phenomena in final states with one or more jets and missing transverse momentum at √s= 13 TeV with the αT variable | ||
CMS Collaboration | ||
August 2016 | ||
Abstract: A search for new-physics phenomena is performed in final states containing one or more jets and an imbalance in transverse momentum in pp collisions at a centre-of-mass energy of 13 TeV. The analysed data sample, recorded with the CMS detector in 2016 at the CERN Large Hadron Collider, corresponds to an integrated luminosity of 12.9 fb−1. Several kinematic variables are employed to strongly suppress the dominant background, multijet production from quantum chromodynamics, as well as discriminate effectively between other standard model and new-physics processes. The search provides sensitivity to a broad range of new-physics models that yield a stable weakly interacting massive particle. The observed candidate events are found to agree with the expected contributions from standard model processes. The result is interpreted in the mass parameter space of simplified supersymmetric models that assume the gluino-mediated and direct production of pairs of third-generation squarks. The gluino mass, and bottom and top squark masses, are excluded up to 1775, 1025, and 875 GeV, respectively. | ||
Links: CDS record (PDF) ; CADI line (restricted) ; |
Figures & Tables | Summary | Additional Figures & Tables | References | CMS Publications |
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Additional information on efficiencies needed for reinterpretation of these results are available here.
An implementation of the calculation of the alphaT variable in C++ is available at this link: code. |
Figures | |
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Figure 1:
(Top panel) Event yields observed in data (solid circles) and SM expectations with their associated uncertainties (black histogram with shaded band) from a CR-only fit as a function of nb and HT for the monojet topology (njet= 1) in the signal region. (Bottom panel). The significance of deviations (pulls) observed in data with respect to the SM expectations from the CR-only (red circles) and full fit (blue circles). The pulls are indicative only and cannot be considered independently. |
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Figure 2:
(Top panel) Event yields observed in data (solid circles) and SM expectations with their associated uncertainties (black histogram with shaded band) from a CR-only fit, integrated over HmissT , as a function of njet , nb , and HT for the asymmetric topology in the signal region. (Bottom panel). The significance of deviations (pulls) observed in data with respect to the SM expectations from the CR-only (red circles) and full fit (blue circles). The pulls are indicative only and cannot be considered independently. |
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Figure 3:
(Top panel) Event yields observed in data (solid circles) and SM expectations with their associated uncertainties (black histogram with shaded band) from a CR-only fit, integrated over HmissT , as a function of njet , nb , and HT for the symmetric topology in the signal region. (Bottom panel). The significance of deviations (pulls) observed in data with respect to the SM expectations from the CR-only (red circles) and full fit (blue circles). The pulls are indicative only and cannot be considered independently. |
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Figure 4:
Event yields observed in data (solid circles) and SM expectations from the CR-only fit with their associated uncertainties (green histogram with shaded band) as a function of HmissT for events in the signal region that satisfy njet≥ 5, HT> 800 GeV , and (Left) nb= 0 or (Right) nb≥ 3. The final bin is the overflow bin. The bottom panels indicate the significance of the deviations (pulls) observed in data with respect to the SM expectations, expressed in terms of the total uncertainty in the SM expectations. The pulls are indicative only and cannot be considered independently. |
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Figure 4-a:
Event yields observed in data (solid circles) and SM expectations from the CR-only fit with their associated uncertainties (green histogram with shaded band) as a function of HmissT for events in the signal region that satisfy njet≥ 5, HT> 800 GeV , and nb= 0. The final bin is the overflow bin. The bottom panels indicate the significance of the deviations (pulls) observed in data with respect to the SM expectations, expressed in terms of the total uncertainty in the SM expectations. The pulls are indicative only and cannot be considered independently. |
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Figure 4-b:
Event yields observed in data (solid circles) and SM expectations from the CR-only fit with their associated uncertainties (green histogram with shaded band) as a function of HmissT for events in the signal region that satisfy njet≥ 5, HT> 800 GeV , and nb≥ 3. The final bin is the overflow bin. The bottom panels indicate the significance of the deviations (pulls) observed in data with respect to the SM expectations, expressed in terms of the total uncertainty in the SM expectations. The pulls are indicative only and cannot be considered independently. |
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Figure 5:
Observed upper limit in cross section at 95% confidence level (indicated by the colour scale) for simplified models that assume the (Top) gluino-mediated or (Bottom) direct production of (Left) bottom or (Right) top squark pairs, as a function of the gluino or squark mass and the ˜χ01 mass. The black solid thick (thin) line indicates the observed mass exclusion regions assuming the nominal (±1σ theory uncertainty) production cross section. The red dashed thick (thin) line indicates the median (±1σ experimental uncertainty) expected mass exclusion regions. |
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Figure 5-a:
Observed upper limit in cross section at 95% confidence level (indicated by the colour scale) for simplified models that assume the gluino-mediated of bottom squark pairs, as a function of the gluino or squark mass and the ˜χ01 mass. The black solid thick (thin) line indicates the observed mass exclusion regions assuming the nominal (±1σ theory uncertainty) production cross section. The red dashed thick (thin) line indicates the median (±1σ experimental uncertainty) expected mass exclusion regions. |
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Figure 5-b:
Observed upper limit in cross section at 95% confidence level (indicated by the colour scale) for simplified models that assume the gluino-mediated of top squark pairs, as a function of the gluino or squark mass and the ˜χ01 mass. The black solid thick (thin) line indicates the observed mass exclusion regions assuming the nominal (±1σ theory uncertainty) production cross section. The red dashed thick (thin) line indicates the median (±1σ experimental uncertainty) expected mass exclusion regions. |
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Figure 5-c:
Observed upper limit in cross section at 95% confidence level (indicated by the colour scale) for simplified models that assume the direct production of bottom squark pairs, as a function of the gluino or squark mass and the ˜χ01 mass. The black solid thick (thin) line indicates the observed mass exclusion regions assuming the nominal (±1σ theory uncertainty) production cross section. The red dashed thick (thin) line indicates the median (±1σ experimental uncertainty) expected mass exclusion regions. |
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Figure 5-d:
Observed upper limit in cross section at 95% confidence level (indicated by the colour scale) for simplified models that assume the direct production of top squark pairs, as a function of the gluino or squark mass and the ˜χ01 mass. The black solid thick (thin) line indicates the observed mass exclusion regions assuming the nominal (±1σ theory uncertainty) production cross section. The red dashed thick (thin) line indicates the median (±1σ experimental uncertainty) expected mass exclusion regions. |
Tables | |
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Table 1:
Summary of the event selection requirements and categorisations used to define the signal region and control samples. |
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Table 2:
Cross section corrections for SM processes determined from data sidebands. |
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Table 3:
Systematic uncertainties in the transfer factors used in the method to estimate the SM backgrounds with genuine →pmissT in the signal region. The quoted ranges provide the minimum and maximum values used across all bins in njet and HT. |
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Table 4:
Representative magnitudes of systematic uncertainties in the experimental acceptance for simplified models that assume the pair production of bottom squarks and their decay to a b quark and a ˜χ0. |
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Table 5:
Summary of the mass limits obtained for the four classes of simplified models. The limits indicate the strongest observed (expected) mass exclusions for the gluino or squarks, and ˜χ01, and the quoted values have uncertainties of ±25 GeV. |
Summary |
An inclusive search for supersymmetry with the CMS experiment is reported, based on a data sample of pp collisions collected in 2016 at √s= 13 TeV, corresponding to an integrated luminosity of 12.9 ± 0.8 fb−1. Final states with jets and significant →pmissT, as expected from the production and decay of massive gluinos and squarks, have been analysed. Candidate signal events are categorised according to the number of reconstructed jets, the number of jets identified to originate from bottom quarks, and the scalar and vector sums of the transverse momentum of jets. The sum of standard model backgrounds per bin has been estimated from a simultaneous binned likelihood fit to event yields in the signal region and control samples. The observed yields in the signal region are found to be in agreement with the expected contributions from standard model processes. Limits are determined in the mass parameter space of simplified models involving the gluino-mediated and direct production of third-generation squark pairs. The excluded mass parameter space extends significantly beyond that set by previous searches, with observed exclusions in gluino mass, and bottom and top squark masses, as high as 1775, 1025, and 875 GeV, respectively. |
Additional Figures | |
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Additional Figure 1:
The αT distribution in data for events satisfying the pre-selection criteria HT>300 GeV and pj2T>100 GeV for αT<0.55 and the full selection for αT>0.55. |
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Additional Figure 2:
The Δϕ∗min distribution in data for events satisfying the pre-selection criteria, HT>800 GeV and pj2T>100 GeV. |
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Additional Figure 3:
The pre-fit HmissT distribution in the category nb=0,1≤njet≤2, for the predicted background, an example of a signal model and the observation. |
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Additional Figure 4:
The post-fit (background-only fit) HmissT distribution in the category nb=0,1≤njet≤2, for the predicted background, an example of a signal model and the observation. |
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Additional Figure 5:
The pre-fit HmissT distribution in the category nb≥1,1≤njet≤2, for the predicted background, an example of a signal model and the observation. |
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Additional Figure 6:
The post-fit (background-only fit) HmissT distribution in the category nb≥1,1≤njet≤2, for the predicted background, an example of a signal model and the observation. |
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Additional Figure 7:
The pre-fit HmissT distribution in the category nb≤1,3≤nasymjet≤4, for the predicted background, an example of a signal model and the observation. |
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Additional Figure 8:
The post-fit (background-only fit) HmissT distribution in the category nb≤1,3≤nasymjet≤4, for the predicted background, an example of a signal model and the observation. |
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Additional Figure 9:
The pre-fit HmissT distribution in the category nb≥2,3≤nasymjet≤4, for the predicted background, an example of a signal model and the observation. |
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Additional Figure 10:
The post-fit (background-only fit) HmissT distribution in the category nb≥2,3≤nasymjet≤4, for the predicted background, an example of a signal model and the observation. |
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Additional Figure 11:
The pre-fit HmissT distribution in the category nb≤1,3≤njet≤4, for the predicted background, an example of a signal model and the observation. |
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Additional Figure 12:
The post-fit (background-only fit) HmissT distribution in the category nb≤1,3≤njet≤4, for the predicted background, an example of a signal model and the observation. |
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Additional Figure 13:
The pre-fit HmissT distribution in the category nb≥2,3≤njet≤4, for the predicted background, an example of a signal model and the observation. |
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Additional Figure 14:
The post-fit (background-only fit) HmissT distribution in the category nb≥2,3≤njet≤4, for the predicted background, an example of a signal model and the observation. |
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Additional Figure 15:
The pre-fit HmissT distribution in the category nb≤1,njet≥5, for the predicted background, an example of a signal model and the observation. |
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Additional Figure 16:
The post-fit (background-only fit) HmissT distribution in the category nb≤1,njet≥5, for the predicted background, an example of a signal model and the observation. |
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Additional Figure 17:
The pre-fit HmissT distribution in the category nb≥2,njet≥5, for the predicted background, an example of a signal model and the observation. |
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Additional Figure 18:
The post-fit (background-only fit) HmissT distribution in the category nb≥2,njet≥5, for the predicted background, an example of a signal model and the observation. |
Additional Tables | |
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Additional Table 1:
The overall efficiency and the efficiency for each selection for a benchmark model of gluino pair production with decay to 4 b-quarks (T1bbbb), corresponding to mGluino= 1000 GeV, mLSP= 900 GeV. The details of the selection can be found in the main document. |
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Additional Table 2:
The overall efficiency and the efficiency for each selection for a benchmark model of gluino pair production with decay to 4 b-quarks (T1bbbb), corresponding to mGluino= 1800 GeV, mLSP= 1 GeV. The details of the selection can be found in the main document. |
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Additional Table 3:
The overall efficiency and the efficiency for each selection for a benchmark model of gluino pair production with decay to 4 top quarks (T1tttt), corresponding to mGluino= 1600 GeV, mLSP= 1 GeV. The details of the selection can be found in the main document. |
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Additional Table 4:
The overall efficiency and the efficiency for each selection for a benchmark model of gluino pair production with decay to 4 top quarks (T1tttt), corresponding to mGluino= 800 GeV, mLSP= 575 GeV. The details of the selection can be found in the main document. |
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Additional Table 5:
The overall efficiency and the efficiency for each selection for a benchmark model of stop pair production with decay to 2 top quarks (T2tt), corresponding to mStop= 300 GeV, mLSP= 200 GeV. The details of the selection can be found in the main document. |
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Additional Table 6:
The overall efficiency and the efficiency for each selection for a benchmark model of stop pair production with decay to 2 top quarks (T2tt), corresponding to mStop= 900 GeV, mLSP= 1 GeV. The details of the selection can be found in the main document. |
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Additional Table 7:
The overall efficiency and the efficiency for each selection for a benchmark model of sbottom pair production with decay to 2 b-quarks (T2bb), corresponding to mSbottom= 1000 GeV, mLSP= 1 GeV. The details of the selection can be found in the main document. |
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Additional Table 8:
The overall efficiency and the efficiency for each selection for a benchmark model of sbottom pair production with decay to 2 b-quarks (T2bb), corresponding to mSbottom= 450 GeV, mLSP= 400 GeV. The details of the selection can be found in the main document. |
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Compact Muon Solenoid LHC, CERN |
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