• Browse all
Search for direct top squark pair production in final states with two leptons in $\sqrt{s} = 13$ TeV $pp$ collisions with the ATLAS detector

The collaboration
No Journal Information, 2017

Abstract (data abstract)
The results of a search for direct pair production of top squarks in events with two leptons (electrons or muons) are reported, using 36.1 fb$^{-1}$ of integrated luminosity from proton--proton collisions at $\sqrt{s}=13$ TeV collected by the ATLAS detector at the Large Hadron Collider. To cover a range of mass differences between the top squark $\tilde{t}$ and lighter supersymmetric particles, four possible decay modes of the top squark are targeted with dedicated selections: the decay $\tilde{t} \rightarrow b \tilde{\chi}_{1}^{\pm}$ into a $b$-quark and the lightest chargino, the decay $\tilde{t} \rightarrow t \tilde{\chi}_{1}^{0}$ into an on-shell top quark and the lightest neutralino, the three-body decay $\tilde{t} \rightarrow b W \tilde{\chi}_{1}^{0}$ and the four-body decay $\tilde{t} \rightarrow b \ell \nu \tilde{\chi}_{1}^{0}$. No significant excess of events is observed above the Standard Model background for any selection, and limits on top squarks are set as a function of the $\tilde{t}$ and $\tilde{\chi}_{1}^{0}$ masses. The results exclude at 95% confidence level $\tilde{\chi}_{1}^{0}$ masses up to about 720 GeV, extending the exclusion region of supersymmetric parameter space covered by previous searches.

• #### Background fit 1

Data from Table 7

10.17182/hepdata.78219.v1/t1

Two-body selection background fit results for the CRs of the SRA$^{2-body}_{180}$ and SRB$^{2-body}_{140}$ background fits. The nominal expectations from MC...

• #### Background fit 2

Data from Table 8

10.17182/hepdata.78219.v1/t2

Two-body selection background fit results for the CRs of the SRC$^{2-body}_{110}$ background fit. The nominal expectations from MC simulation are...

• #### CR kinematics 1

Data from Figure 2a

10.17182/hepdata.78219.v1/t3

Two-body selection distribution of $n_{jets}$ in CR$^{2-body}_{top}$ after the background fits. The contributions from all SM backgrounds are shown as...

• #### CR kinematics 2

Data from Figure 2b

10.17182/hepdata.78219.v1/t4

Two-body selection distribution of $R_{2\ell 2j}$ in $CR^{2-body}_{VV-SF}$ after the background fits. The contributions from all SM backgrounds are shown...

• #### CR kinematics 3

Data from Figure 2c

10.17182/hepdata.78219.v1/t5

Two-body selection distribution of $E_{T,corr}^{miss}$ in $CR_{ttZ}$ after the background fits. The contributions from all SM backgrounds are shown as...

• #### CR kinematics 4

Data from Figure 2d

10.17182/hepdata.78219.v1/t6

Two-body selection distribution of $E_{T,corr}^{miss}$ in $CR_{VZ}$ after the background fits. The contributions from all SM backgrounds are shown as...

• #### Background fit 3

Data from Table 10

10.17182/hepdata.78219.v1/t7

Three-body selection background fit results for the CRs of the SR$^{3-body}_{W}$ and SR$^{3-body}_{t}$ background fit. The nominal expectations from MC...

• #### CR kinematics 5

Data from Figure 3a

10.17182/hepdata.78219.v1/t8

Three-body selection distributions of $R_{p_{T}}$ in $CR^{3-body}_{t\bar{t}}$ after the background fit. The contributions from all SM backgrounds are shown as...

• #### CR kinematics 6

Data from Figure 3b

10.17182/hepdata.78219.v1/t9

Three-body selection distributions of $cos\theta_{b}$ in $CR^{3-body}_{VV-DF}$ after the background fit. The contributions from all SM backgrounds are shown as...

• #### CR kinematics 7

Data from Figure 3c

10.17182/hepdata.78219.v1/t10

Three-body selection distributions of $M_{\Delta}^{R}$ in $CR^{3-body}_{VV-SF}$ after the background fit. The contributions from all SM backgrounds are shown as...

• #### Background fit 4

Data from Table 12

10.17182/hepdata.78219.v1/t11

Four-body selection background fit results for the CRs of the SR$^{4-body}$ background fit. The nominal expectations from MC simulation are...

• #### CR kinematics 8

Data from Figure 4a

10.17182/hepdata.78219.v1/t12

Four-body selection distributions of the $p_{T}(j_1)$ in CR$^{4-body}_{t\bar{t}}$ after the background fit. The contributions from all SM backgrounds are shown...

• #### CR kinematics 9

Data from Figure 4b

10.17182/hepdata.78219.v1/t13

Four-body selection distributions of the $R_{2\ell}$ in CR$^{4-body}_{VV}$ after the background fit. The contributions from all SM backgrounds are shown...

• #### CR kinematics 10

Data from Figure 4c

10.17182/hepdata.78219.v1/t14

Four-body selection distributions of the $E^{miss}_{T}$ in CR$^{4-body}_{Z\tau\tau}$ after the background fit. The contributions from all SM backgrounds are shown...

• #### Background fit 5

Data from Table 15

10.17182/hepdata.78219.v1/t15

Two-body selection background fit results for SRA$^{2-body}_{180}$ and SRB$^{2-body}_{140}$. The nominal expectations from MC simulation are given for comparison for...

• #### Background fit 6

Data from Table 15

10.17182/hepdata.78219.v1/t16

Two-body selection background fit results for SRC$^{2-body}_{110}$. The nominal expectations from MC simulation are given for comparison for those backgrounds...

• #### SR kinematics 1

Data from Figure 6a

10.17182/hepdata.78219.v1/t17

Two-body selection distributions of $m_{T2}^{ll}$ for events satisfying the selection criteria of the six SRs, except for the one on...

• #### SR kinematics 2

Data from Figure 6b

10.17182/hepdata.78219.v1/t18

Two-body selection distributions of $m_{T2}^{ll}$ for events satisfying the selection criteria of the six SRs, except for the one on...

• #### SR kinematics 3

Data from Figure 6c

10.17182/hepdata.78219.v1/t19

Two-body selection distributions of $m_{T2}^{ll}$ for events satisfying the selection criteria of the six SRs, except for the one on...

• #### SR kinematics 4

Data from Figure 6d

10.17182/hepdata.78219.v1/t20

Two-body selection distributions of $m_{T2}^{ll}$ for events satisfying the selection criteria of the six SRs, except for the one on...

• #### SR kinematics 5

Data from Figure 6e

10.17182/hepdata.78219.v1/t21

Two-body selection distributions of $m_{T2}^{ll}$ for events satisfying the selection criteria of the six SRs, except for the one on...

• #### SR kinematics 6

Data from Figure 6f

10.17182/hepdata.78219.v1/t22

Two-body selection distributions of $m_{T2}^{ll}$ for events satisfying the selection criteria of the six SRs, except for the one on...

• #### Background fit 7

Data from Table 16

10.17182/hepdata.78219.v1/t23

Two-body selection background fit results for SR(A,B)$^{2-body}_{x,y}$ regions, where x and y denote the low and high edges of the...

• #### Background fit 8

Data from Table 17

10.17182/hepdata.78219.v1/t24

Three-body selection background fit results for SR$^{3-body}_{W}$ and SR$^{3-body}_{t}$. Combined statistical and systematic uncertainties are given. Uncertainties on the predicted...

• #### SR kinematics 7

Data from Figure 7a

10.17182/hepdata.78219.v1/t25

Three-body selection distributions of $R_{p_{T}}$ in same-flavour events that satisfy all the SR$^{3-body}_{W}$ selection criteria except for the one on...

• #### SR kinematics 8

Data from Figure 7b

10.17182/hepdata.78219.v1/t26

Three-body selection distributions of $R_{p_{T}}$ in different-flavour events that satisfy all the SR$^{3-body}_{W}$ selection criteria except for the one on...

• #### SR kinematics 9

Data from Figure 7c

10.17182/hepdata.78219.v1/t27

Three-body selection distributions of $M_{\Delta}^{R}$ in same-flavour events that satisfy all the SR$^{3-body}_{t}$ selection criteria except for the one on...

• #### SR kinematics 10

Data from Figure 7d

10.17182/hepdata.78219.v1/t28

Three-body selection distributions of $M_{\Delta}^{R}$ in different-flavour events that satisfy all the SR$^{3-body}_{t}$ selection criteria except for the one on...

• #### SR kinematics 11

Data from Figure 8a

10.17182/hepdata.78219.v1/t29

Four-body selection distributions of $R_{2\ell 4j}$ for events satisfying all the SR$^{4-body}$ selections but for the one on the variable...

• #### SR kinematics 12

Data from Figure 8b

10.17182/hepdata.78219.v1/t30

Four-body selection distributions of $R_{2\ell}$ for events satisfying all the SR$^{4-body}$ selections but for the one on the variable shown...

• #### Background fit 9

Data from Table 18

10.17182/hepdata.78219.v1/t31

Four-body selection background fit results for SR$^{4-body}$. The nominal expectations from MC simulation are given for comparison for those backgrounds...

• #### Model-independent limits

Data from Table 19

10.17182/hepdata.78219.v1/t32

• #### Cross section Upper Limits 2

Data from auxiliary Figure 9

10.17182/hepdata.78219.v1/t60