Search for a scalar partner of the top quark in the all-hadronic $t{\bar{t}}$ plus missing transverse momentum final state at $\sqrt{s}=13$ TeV with the ATLAS detector

The collaboration
Eur.Phys.J.C 80 (2020) 737, 2020.

Abstract
A search for direct pair production of scalar partners of the top quark (top squarks or scalar third-generation up-type leptoquarks) in the all-hadronic $t\bar{t}$ plus missing transverse momentum final state is presented. The analysis of 139 fb$^{-1}$ of ${\sqrt{s}=13}$ TeV proton-proton collision data collected using the ATLAS detector at the LHC yields no significant excess over the Standard Model background expectation. To interpret the results, a supersymmetric model is used where the top squark decays via $\tilde{t} \to t^{(*)} \tilde{\chi}^0_1$, with $t^{(*)}$ denoting an on-shell (off-shell) top quark and $\tilde{\chi}^0_1$ the lightest neutralino. Three specific event selections are optimised for the following scenarios. In the scenario where $m_{\tilde{t}}> m_t+m_{\tilde{\chi}^0_1}$, top squark masses are excluded in the range 400-1250 GeV for $\tilde{\chi}^0_1$ masses below $200$ GeV at 95 % confidence level. In the situation where $m_{\tilde{t}}\sim m_t+m_{\tilde{\chi}^0_1}$, top squark masses in the range 300-630 GeV are excluded, while in the case where $m_{\tilde{t}}< m_W+m_b+m_{\tilde{\chi}^0_1}$ (with $m_{\tilde{t}}-m_{\tilde{\chi}^0_1}\ge 5$ GeV), considered for the first time in an ATLAS all-hadronic search, top squark masses in the range 300-660 GeV are excluded. Limits are also set for scalar third-generation up-type leptoquarks, excluding leptoquarks with masses below $1240$ GeV when considering only leptoquark decays into a top quark and a neutrino.

• #### Overview

10.17182/hepdata.93906.v2/t1

- - - - - - - - Overview of HEPData Record - - - - - - - -...

• #### stop_obs

Data from fig. 13a.

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The observed exclusion contour at 95% CL as a function of the $\it{m}_{\tilde{\chi}^{0}_{1}}$ vs. $\it{m}_{\tilde{t}}$. Masses that are within the...

• #### stop_exp

Data from fig. 13a.

10.17182/hepdata.93906.v2/t3

The expected exclusion contour at 95% CL as a function of the $\it{m}_{\tilde{\chi}^{0}_{1}}$ vs. $\it{m}_{\tilde{t}}$. Masses that are within the...

• #### stop_obs_down

Data from fig. 13a.

10.17182/hepdata.93906.v2/t4

The minus $1\sigma$ variation of observed exclusion contour obtained by varying the signal cross section within its uncertainty. The contour...

• #### stop_obs_up

Data from fig. 13a.

10.17182/hepdata.93906.v2/t5

The plus $1\sigma$ variation of observed exclusion contour obtained by varying the signal cross section within its uncertainty. The contour...

• #### stop_exp_down

Data from fig. 13a.

10.17182/hepdata.93906.v2/t6

The minus $1\sigma$ variation of expected exclusion contour obtained by varying MC statistical uncertainties, detector-related systematic uncertainties, and theoretical uncertainties...

• #### stop_exp_up

Data from fig. 13a.

10.17182/hepdata.93906.v2/t7

The plus $1\sigma$ variation of expected exclusion contour obtained by varying MC statistical uncertainties, detector-related systematic uncertainties, and theoretical uncertainties...

• #### LQ3u_obs

Data from fig. 14a.

10.17182/hepdata.93906.v2/t8

The observed exclusion contour at 95% CL as a function of the $\it{m}_{LQ_{3}^{u}}$ vs. $\mathrm{BR}(\it{m}_{LQ_{3}^{u}}\rightarrow b \tau)$. Points that are...

• #### LQ3u_exp

Data from fig. 14a.

10.17182/hepdata.93906.v2/t9

The expected exclusion contour at 95% CL as a function of the $\it{m}_{LQ_{3}^{u}}$ vs. $\mathrm{BR}(\it{m}_{LQ_{3}^{u}}\rightarrow b \tau)$. Points that are...

• #### LQ3u_obs_down

Data from fig. 14a.

10.17182/hepdata.93906.v2/t10

The minus $1\sigma$ variation of observed exclusion contour obtained by varying the signal cross section within its uncertainty. The contour...

• #### LQ3u_obs_up

Data from fig. 14a.

10.17182/hepdata.93906.v2/t11

The plus $1\sigma$ variation of observed exclusion contour obtained by varying the signal cross section within its uncertainty. The contour...

• #### LQ3u_exp_up

Data from fig. 14a.

10.17182/hepdata.93906.v2/t12

The plus $1\sigma$ variation of expected exclusion contour obtained by varying MC statistical uncertainties, detector-related systematic uncertainties, and theoretical uncertainties...

• #### LQ3u_exp_down

Data from fig. 14a.

10.17182/hepdata.93906.v2/t13

The minus $1\sigma$ variation of expected exclusion contour obtained by varying MC statistical uncertainties, detector-related systematic uncertainties, and theoretical uncertainties...

• #### stop_xSecUpperLimit_obs

Data from figaux. 01a and 01b.

10.17182/hepdata.93906.v2/t14

Model dependent upper limit on the cross section for the $(\tilde{t},\tilde{\chi}^{0}_{1})$ signal grid. The column titled 'Leading Region' stores information...

• #### stop_xSecUpperLimit_exp

Data from figaux. 02a and 02b.

10.17182/hepdata.93906.v2/t15

Expected model dependent upper limit on the cross section for the $(\tilde{t},\tilde{\chi}^{0}_{1})$ signal grid. The column titled 'Leading Region' stores...

• #### LQ3u_xSecUpperLimit_obs

Data from fig. 14b.

10.17182/hepdata.93906.v2/t16

Model dependent upper limit on the cross section for the $LQ_{3}^{u}$ signal grid with $\mathrm{BR}(\it{m}_{LQ_{3}^{u}}\rightarrow b \tau))=0$ %. Only the...

• #### LQ3u_xSecUpperLimit_exp

Data from fig. 14b.

10.17182/hepdata.93906.v2/t17

Expected model dependent upper limit on the cross section for the $LQ_{3}^{u}$ signal grid with $\mathrm{BR}(\it{m}_{LQ_{3}^{u}}\rightarrow b \tau))=0$ %. Only...

• #### SRATW_metsigST

Data from fig. 12a.

10.17182/hepdata.93906.v2/t18

The distributions of $S$ in SRA-TW. For each bin yields for the data, total SM prediction and a representative signal...

• #### SRBTT_m_1fatjet_kt12

Data from fig. 12b.

10.17182/hepdata.93906.v2/t19

The distributions of $\it{m}^{\mathrm{R=1.2}}_{1}$ in SRB-TT. For each bin yields for the data, total SM prediction and a representative signal...

• #### SRC_RISR

Data from fig. 12c.

10.17182/hepdata.93906.v2/t20

The distributions of R$_{ISR}$ in SRC signal regions before R$_{ISR}$ cuts are applied. For each bin yields for the data,...

• #### SRD0_htSig

Data from fig. 12d.

10.17182/hepdata.93906.v2/t21

The distributions of $E^{miss}_{T}/\sqrt{H_{T}}$ in SRD0. For each bin yields for the data, total SM prediction and a representative signal...

• #### SRD1_htSig

Data from fig. 12e.

10.17182/hepdata.93906.v2/t22

The distributions of $E^{miss}_{T}/\sqrt{H_{T}}$ in SRD1. For each bin yields for the data, total SM prediction and a representative signal...

• #### SRD2_htSig

Data from fig. 12f.

10.17182/hepdata.93906.v2/t23

The distributions of $E^{miss}_{T}/\sqrt{H_{T}}$ in SRD2. For each bin yields for the data, total SM prediction and a representative signal...

• #### cutflow_SRATT

Data from tabaux. 01.

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Cutflow for the reference point $(\it{m}_{\tilde{t}}, \it{m}_{\tilde{\chi}^{0}_{1}})= (1300,1)\ \mathrm{GeV}$ in SRA-TT. The column labelled ''Weighted yield'' shows the results...

• #### cutflow_SRATW

Data from tabaux. 02.

10.17182/hepdata.93906.v2/t25

Cutflow for the reference point $(\it{m}_{\tilde{t}}, \it{m}_{\tilde{\chi}^{0}_{1}})= (1300,1)\ \mathrm{GeV}$ in SRA-TW. The column labelled ''Weighted yield'' shows the results...

• #### cutflow_SRAT0

Data from tabaux. 03.

10.17182/hepdata.93906.v2/t26

Cutflow for the reference point $(\it{m}_{\tilde{t}}, \it{m}_{\tilde{\chi}^{0}_{1}})= (1300,1)\ \mathrm{GeV}$ in SRA-T0. The column labelled ''Weighted yield'' shows the results...

• #### cutflow_SRB

Data from tabaux. 04.

10.17182/hepdata.93906.v2/t27

Cutflow for the reference point $(\it{m}_{\tilde{t}}, \it{m}_{\tilde{\chi}^{0}_{1}})= (700,400)\ \mathrm{GeV}$ in signal regions SRB-TT, SRB-TW and SRB-T0. The regions differ...

• #### cutflow_SRC

Data from tabaux. 05.

10.17182/hepdata.93906.v2/t28

Cutflow for the reference point $(\it{m}_{\tilde{t}}, \it{m}_{\tilde{\chi}^{0}_{1}})= (500,327)\ \mathrm{GeV}$ in regions SRC-1, SRC-2, SRC-3, SRC-4 and SRC-5. The regions...

• #### cutflow_SRD0

Data from tabaux. 06.

10.17182/hepdata.93906.v2/t29

Cutflow for the reference point $(\it{m}_{\tilde{t}}, \it{m}_{\tilde{\chi}^{0}_{1}})= (550,500)\ \mathrm{GeV}$ in SRD0. The column labelled ''Weighted yield'' shows the results...

• #### cutflow_SRD1

Data from tabaux. 07.

10.17182/hepdata.93906.v2/t30

Cutflow for the reference point $(\it{m}_{\tilde{t}}, \it{m}_{\tilde{\chi}^{0}_{1}})= (550,500)\ \mathrm{GeV}$ in SRD1. The column labelled ''Weighted yield'' shows the results...

• #### cutflow_SRD2

Data from tabaux. 08.

10.17182/hepdata.93906.v2/t31

Cutflow for the reference point $(\it{m}_{\tilde{t}}, \it{m}_{\tilde{\chi}^{0}_{1}})= (550,500)\ \mathrm{GeV}$ in SRD2. The column labelled ''Weighted yield'' shows the results...

• #### Acc_SRATT

Data from figaux 03a.

10.17182/hepdata.93906.v2/t32

Signal acceptance in SRA-TT for simplified $(\tilde{t},\tilde{\chi^{0}_1})$ model. Please mind that the acceptance given in the table is multiplied by...

• #### Eff_SRATT

Data from figaux 03b.

10.17182/hepdata.93906.v2/t33

Signal efficiency in SRA-TT for simplified $(\tilde{t},\tilde{\chi^{0}_1})$ model. Please mind that the efficiency in the table is reported in %.

• #### Acc_SRATW

Data from figaux 04a.

10.17182/hepdata.93906.v2/t34

Signal acceptance in SRA-TW for simplified $(\tilde{t},\tilde{\chi^{0}_1})$ model. Please mind that the acceptance given in the table is multiplied by...

• #### Eff_SRATW

Data from figaux 04b.

10.17182/hepdata.93906.v2/t35

Signal efficiency in SRA-TW for simplified $(\tilde{t},\tilde{\chi^{0}_1})$ model. Please mind that the efficiency in the table is reported in %.

• #### Acc_SRAT0

Data from figaux 05a.

10.17182/hepdata.93906.v2/t36

Signal acceptance in SRA-T0 for simplified $(\tilde{t},\tilde{\chi^{0}_1})$ model. Please mind that the acceptance given in the table is multiplied by...

• #### Eff_SRAT0

Data from figaux 05b.

10.17182/hepdata.93906.v2/t37

Signal efficiency in SRA-T0 for simplified $(\tilde{t},\tilde{\chi^{0}_1})$ model. Please mind that the efficiency in the table is reported in %.

• #### Acc_SRBTT

Data from figaux 06a.

10.17182/hepdata.93906.v2/t38

Signal acceptance in SRB-TT for simplified $(\tilde{t},\tilde{\chi^{0}_1})$ model. Please mind that the acceptance given in the table is multiplied by...

• #### Eff_SRBTT

Data from figaux 06b.

10.17182/hepdata.93906.v2/t39

Signal efficiency in SRB-TT for simplified $(\tilde{t},\tilde{\chi^{0}_1})$ model. Please mind that the efficiency in the table is reported in %.

• #### Acc_SRBTW

Data from figaux 07a.

10.17182/hepdata.93906.v2/t40

Signal acceptance in SRB-TW for simplified $(\tilde{t},\tilde{\chi^{0}_1})$ model. Please mind that the acceptance given in the table is multiplied by...

• #### Eff_SRBTW

Data from figaux 07b.

10.17182/hepdata.93906.v2/t41

Signal efficiency in SRB-TW for simplified $(\tilde{t},\tilde{\chi^{0}_1})$ model. Please mind that the efficiency in the table is reported in %.

• #### Acc_SRBT0

Data from figaux 08a.

10.17182/hepdata.93906.v2/t42

Signal acceptance in SRB-T0 for simplified $(\tilde{t},\tilde{\chi^{0}_1})$ model. Please mind that the acceptance given in the table is multiplied by...

• #### Eff_SRBT0

Data from figaux 08b.

10.17182/hepdata.93906.v2/t43

Signal efficiency in SRB-T0 for simplified $(\tilde{t},\tilde{\chi^{0}_1})$ model. Please mind that the efficiency in the table is reported in %.

• #### Acc_SRC1

Data from figaux 09a.

10.17182/hepdata.93906.v2/t44

Signal acceptance in SRC1 for simplified $(\tilde{t},\tilde{\chi^{0}_1})$ model. Please mind that the acceptance given in the table is multiplied by...

• #### Eff_SRC1

Data from figaux 09b.

10.17182/hepdata.93906.v2/t45

Signal efficiency in SRC1 for simplified $(\tilde{t},\tilde{\chi^{0}_1})$ model. Please mind that the efficiency in the table is reported in %...

• #### Acc_SRC2

Data from figaux 10a.

10.17182/hepdata.93906.v2/t46

Signal acceptance in SRC2 for simplified $(\tilde{t},\tilde{\chi^{0}_1})$ model. Please mind that the acceptance given in the table is multiplied by...

• #### Eff_SRC2

Data from figaux 10b.

10.17182/hepdata.93906.v2/t47

Signal efficiency in SRC2 for simplified $(\tilde{t},\tilde{\chi^{0}_1})$ model. Please mind that the efficiency in the table is reported in %...

• #### Acc_SRC3

Data from figaux 11a.

10.17182/hepdata.93906.v2/t48

Signal acceptance in SRC3 for simplified $(\tilde{t},\tilde{\chi^{0}_1})$ model. Please mind that the acceptance given in the table is multiplied by...

• #### Eff_SRC3

Data from figaux 11b.

10.17182/hepdata.93906.v2/t49

Signal efficiency in SRC3 for simplified $(\tilde{t},\tilde{\chi^{0}_1})$ model. Please mind that the efficiency in the table is reported in %...

• #### Acc_SRC4

Data from figaux 12a.

10.17182/hepdata.93906.v2/t50

Signal acceptance in SRC4 for simplified $(\tilde{t},\tilde{\chi^{0}_1})$ model. Please mind that the acceptance given in the table is multiplied by...

• #### Eff_SRC4

Data from figaux 12b.

10.17182/hepdata.93906.v2/t51

Signal efficiency in SRC4 for simplified $(\tilde{t},\tilde{\chi^{0}_1})$ model. Please mind that the efficiency in the table is reported in %...

• #### Acc_SRC5

Data from figaux 13a.

10.17182/hepdata.93906.v2/t52

Signal acceptance in SRC5 for simplified $(\tilde{t},\tilde{\chi^{0}_1})$ model. Please mind that the acceptance given in the table is multiplied by...

• #### Eff_SRC5

Data from figaux 13b.

10.17182/hepdata.93906.v2/t53

Signal efficiency in SRC5 for simplified $(\tilde{t},\tilde{\chi^{0}_1})$ model. Please mind that the efficiency in the table is reported in %...

• #### Acc_SRD0

Data from figaux 14a.

10.17182/hepdata.93906.v2/t54

Signal acceptance in SRD0 for simplified $(\tilde{t},\tilde{\chi^{0}_1})$ model. Please mind that the acceptance given in the table is multiplied by...

• #### Eff_SRD0

Data from figaux 14b.

10.17182/hepdata.93906.v2/t55

Signal efficiency in SRD0 for simplified $(\tilde{t},\tilde{\chi^{0}_1})$ model. Please mind that the efficiency in the table is reported in %...

• #### Acc_SRD1

Data from figaux 15a.

10.17182/hepdata.93906.v2/t56

Signal acceptance in SRD1 for simplified $(\tilde{t},\tilde{\chi^{0}_1})$ model. Please mind that the acceptance given in the table is multiplied by...

• #### Eff_SRD1

Data from figaux 15b.

10.17182/hepdata.93906.v2/t57

Signal efficiency in SRD1 for simplified $(\tilde{t},\tilde{\chi^{0}_1})$ model. Please mind that the efficiency in the table is reported in %...

• #### Acc_SRD2

Data from figaux 16a.

10.17182/hepdata.93906.v2/t58

Signal acceptance in SRD2 for simplified $(\tilde{t},\tilde{\chi^{0}_1})$ model. Please mind that the acceptance given in the table is multiplied by...

• #### Eff_SRD2

Data from figaux 16b.

10.17182/hepdata.93906.v2/t59

Signal efficiency in SRD2 for simplified $(\tilde{t},\tilde{\chi^{0}_1})$ model. Please mind that the efficiency in the table is reported in %...

Version 2 modifications: Update of the SimpleAnalysis implementation