Search for new phenomena in $pp$ collisions in final states with tau leptons, $b$-jets, and missing transverse momentum with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Braden Keim ; Abbott, Dale ; et al.
Phys.Rev.D 104 (2021) 112005, 2021.
Inspire Record 1907601 DOI 10.17182/hepdata.105998

A search for new phenomena in final states with hadronically decaying tau leptons, $b$-jets, and missing transverse momentum is presented. The analyzed dataset comprises $pp$~collision data at a center-of-mass energy of $\sqrt s = 13$ TeV with an integrated luminosity of 139/fb, delivered by the Large Hadron Collider and recorded with the ATLAS detector from 2015 to 2018. The observed data are compatible with the expected Standard Model background. The results are interpreted in simplified models for two different scenarios. The first model is based on supersymmetry and considers pair production of top squarks, each of which decays into a $b$-quark, a neutrino and a tau slepton. Each tau slepton in turn decays into a tau lepton and a nearly massless gravitino. Within this model, top-squark masses up to 1.4 TeV can be excluded at the 95% confidence level over a wide range of tau-slepton masses. The second model considers pair production of leptoquarks with decays into third-generation leptons and quarks. Depending on the branching fraction into charged leptons, leptoquarks with masses up to around 1.25 TeV can be excluded at the 95% confidence level for the case of scalar leptoquarks and up to 1.8 TeV (1.5 TeV) for vector leptoquarks in a Yang--Mills (minimal-coupling) scenario. In addition, model-independent upper limits are set on the cross section of processes beyond the Standard Model.

89 data tables

Relative systematic uncertainties in the estimated number of background events in the signal regions. In the lower part of the table, a breakdown of the total uncertainty into different categories is given. For the multi-bin SR, the breakdown refers to the integral over all three $p_{\text{T}}(\tau)$ bins. As the individual uncertainties are correlated, they do not add in quadrature to equal the total background uncertainty.

Distributions of $m_{\text{T}2}(\tau_{1},\tau_{2})$ in the di-tau SR. The stacked histograms show the various SM background contributions. The hatched band indicates the total statistical and systematic uncertainty of the SM background. The $t\bar{t}$ (2 real $\tau$) and $t\bar{t}$ (1 real $\tau$) as well as the single-top background contributions are scaled with the normalization factors obtained from the background-only fit. Minor backgrounds are grouped together and denoted as 'Other'. This includes $t\bar{t}$-fake, single top, and other top (di-tau channel) or $t\bar{t}$-fake, $t\bar{t}+H$, multiboson, and other top (single-tau channel). The overlaid dotted lines show the additional contributions for signal scenarios close to the expected exclusion contour with the particle type and the mass and $\beta$ parameters for the simplified models indicated in the legend. For the leptoquark signal model the shapes of the distributions for $\text{LQ}_{3}^{\text{d}}$ and $\text{LQ}_{3}^{\text{v}}$ (not shown) are similar to that of $\text{LQ}_{3}^{\text{u}}$. The rightmost bin includes the overflow.

Distributions of $E_{\text{T}}^{\text{miss}}$ in the di-tau SR. The stacked histograms show the various SM background contributions. The hatched band indicates the total statistical and systematic uncertainty of the SM background. The $t\bar{t}$ (2 real $\tau$) and $t\bar{t}$ (1 real $\tau$) as well as the single-top background contributions are scaled with the normalization factors obtained from the background-only fit. Minor backgrounds are grouped together and denoted as 'Other'. This includes $t\bar{t}$-fake, single top, and other top (di-tau channel) or $t\bar{t}$-fake, $t\bar{t}+H$, multiboson, and other top (single-tau channel). The overlaid dotted lines show the additional contributions for signal scenarios close to the expected exclusion contour with the particle type and the mass and $\beta$ parameters for the simplified models indicated in the legend. For the leptoquark signal model the shapes of the distributions for $\text{LQ}_{3}^{\text{d}}$ and $\text{LQ}_{3}^{\text{v}}$ (not shown) are similar to that of $\text{LQ}_{3}^{\text{u}}$. The rightmost bin includes the overflow.

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Two-particle azimuthal correlations in photonuclear ultraperipheral Pb+Pb collisions at 5.02 TeV with ATLAS

The ATLAS collaboration Aad, Georges ; Abbott, Braden Keim ; Abbott, Brad ; et al.
Phys.Rev.C 104 (2021) 014903, 2021.
Inspire Record 1842843 DOI 10.17182/hepdata.114165

Two-particle long-range azimuthal correlations are measured in photonuclear collisions using 1.7 nb$^{-1}$ of 5.02 TeV Pb+Pb collision data collected by the ATLAS experiment at the LHC. Candidate events are selected using a dedicated high-multiplicity photonuclear event trigger, a combination of information from the zero-degree calorimeters and forward calorimeters, and from pseudorapidity gaps constructed using calorimeter energy clusters and charged-particle tracks. Distributions of event properties are compared between data and Monte Carlo simulations of photonuclear processes. Two-particle correlation functions are formed using charged-particle tracks in the selected events, and a template-fitting method is employed to subtract the non-flow contribution to the correlation. Significant nonzero values of the second- and third-order flow coefficients are observed and presented as a function of charged-particle multiplicity and transverse momentum. The results are compared with flow coefficients obtained in proton-proton and proton-lead collisions in similar multiplicity ranges, and with theoretical expectations. The unique initial conditions present in this measurement provide a new way to probe the origin of the collective signatures previously observed only in hadronic collisions.

2 data tables

The measured $v_2$ and $v_3$ charged-particle anisotropies as a function of charged-particle multiplicity in photonuclear collisions

The measured $v_2$ and $v_3$ charged-particle anisotropies as a function of charged-particle transverse momentum in photonuclear collisions


Search for Higgs boson decays into a pair of pseudoscalar particles in the $bb\mu\mu$ final state with the ATLAS detector in $pp$ collisions at $\sqrt{s}=13$ TeV

The ATLAS collaboration Aad, Georges ; Abbott, Braden Keim ; Abbott, Dale ; et al.
Phys.Rev.D 105 (2022) 012006, 2022.
Inspire Record 1937344 DOI 10.17182/hepdata.107761

This paper presents a search for decays of the Higgs boson with a mass of 125 GeV into a pair of new pseudoscalar particles, $H\rightarrow aa$, where one $a$-boson decays into a $b$-quark pair and the other into a muon pair. The search uses 139 fb$^{-1}$ of proton-proton collision data at a center-of-mass energy of $\sqrt{s}=13$ TeV recorded between 2015 and 2018 by the ATLAS experiment at the LHC. A narrow dimuon resonance is searched for in the invariant mass spectrum between 16 GeV and 62 GeV. The largest excess of events above the Standard Model backgrounds is observed at a dimuon invariant mass of 52 GeV and corresponds to a local (global) significance of $3.3 \sigma$ ($1.7 \sigma$). Upper limits at 95% confidence level are placed on the branching ratio of the Higgs boson to the $bb\mu\mu$ final state, $\mathcal{B}(H\rightarrow aa\rightarrow bb\mu\mu)$, and are in the range $\text{(0.2-4.0)} \times 10^{-4}$, depending on the signal mass hypothesis.

11 data tables

Post-fit number of background events in all SR bins (after applying the BDT cuts) that are tested for the presence of signal. The bins are 2 GeV (3 GeV) wide in mmumu for ma ≤ 45 GeV (ma > 45 GeV). Events in neighbouring bins partially overlap. Discontinuities in the background predictions appear when the BDT discriminant used for the selection changes from the one trained in the lower mass range to the one trained in the higher mass range.

Post-fit number of background events in all SR bins without applying the BDT cuts that are tested for the presence of signal. The bins are 2 GeV (3 GeV) wide in mµµ for $m_a$ ≤ 45 GeV ($m_a$ > 45 GeV). Events in neighbouring bins partially overlap. Discontinuities in the background predictions appear when the BDT discriminant used for the selection changes from the one trained in the lower mass range to the one trained in the higher mass range.

Probability that the observed spectrum is compatible with the background-only hypothesis. The local $p_0$-values are quantified in standard deviations $\sigma$.

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Search for events with a pair of displaced vertices from long-lived neutral particles decaying into hadronic jets in the ATLAS muon spectrometer in pp collisions at $\sqrt{s}=13$ TeV

The ATLAS collaboration Aad, Georges ; Abbott, Braden Keim ; Abbott, Dale ; et al.
Phys.Rev.D 106 (2022) 032005, 2022.
Inspire Record 2040545 DOI 10.17182/hepdata.127764

A search for events with two displaced vertices from long-lived particles (LLP) pairs using data collected by the ATLAS detector at the LHC is presented. This analysis uses 139~fb$^{-1}$ of proton-proton collision data at $\sqrt{s}=13$ TeV recorded in 2015-2018. The search employs techniques for reconstructing vertices of LLPs decaying to jets in the muon spectrometer displaced between 3 m and 14 m with respect to the primary interaction vertex. The observed numbers of events are consistent with the expected background and limits for several benchmark signals are determined. For the Higgs boson with a mass of 125 GeV, the paper reports the first exclusion limits for branching fractions into neutral long-lived particles below 0.1%, while branching fractions above 10% are excluded at 95% confidence level for LLP proper lifetimes ranging from 4 cm to 72.4 m. In addition, the paper present the first results for the decay of LLPs into into $t\bar{t}$ in the ATLAS muon spectrometer.

116 data tables

Efficiency for the Muon RoI Cluster trigger as a function of the decay position of the LLP for some scalar portal samples in the MS barrel for events passing the data quality requirements and having a reconstructed primary vertex. These efficiency distributions are based solely on MC simulation, without any corrections applied for mismodeling. The vertical lines show the relevant detector boundaries, where “HCal end” is the outer limit of the hadronic calorimeter, “RPC 1/2” represent the first/second stations of RPC chambers, “TGC 1” represents the first stations of TGC chambers and “L/S” indicate whether they are in the Large or Small sectors.

Efficiency for the Muon RoI Cluster trigger as a function of the decay position of the LLP for some scalar portal samples in the MS endcaps for events passing the data quality requirements and having a reconstructed primary vertex. These efficiency distributions are based solely on MC simulation, without any corrections applied for mismodeling. The vertical lines show the relevant detector boundaries, where “HCal end” is the outer limit of the hadronic calorimeter, “RPC 1/2” represent the first/second stations of RPC chambers, “TGC 1” represents the first stations of TGC chambers and “L/S” indicate whether they are in the Large or Small sectors.

Efficiency to reconstruct an MS DV in the MS barrel fiducial volume as a function of the transverse decay position of the LLP for scalar portal samples with $m_\varPhi=125$~\GeV\ for vertices that pass the baseline event selection and satisfy the vertex isolation criteria. The efficiency distributions are corrected for mismodeling. The vertical lines show the relevant detector boundaries, where ``HCal end'' is the outer limit of the hadronic calorimeter, ``MDT 1/2'' represent the first/second stations of MDT chambers and ``L/S'' indicate whether they are in Large or Small sectors.

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Version 3
Search for charginos and neutralinos in final states with two boosted hadronically decaying bosons and missing transverse momentum in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Braden Keim ; Abbott, Dale ; et al.
Phys.Rev.D 104 (2021) 112010, 2021.
Inspire Record 1906174 DOI 10.17182/hepdata.104458

A search for charginos and neutralinos at the Large Hadron Collider is reported using fully hadronic final states and missing transverse momentum. Pair-produced charginos or neutralinos are explored, each decaying into a high-$p_{\text{T}}$ Standard Model weak boson. Fully-hadronic final states are studied to exploit the advantage of the large branching ratio, and the efficient background rejection by identifying the high-$p_{\text{T}}$ bosons using large-radius jets and jet substructure information. An integrated luminosity of 139 fb$^{-1}$ of proton-proton collision data collected by the ATLAS detector at a center-of-mass energy of 13 TeV is used. No significant excess is found beyond the Standard Model expectation. The 95% confidence level exclusion limits are set on wino or higgsino production with varying assumptions in the decay branching ratios and the type of the lightest supersymmetric particle. A wino (higgsino) mass up to 1060 (900) GeV is excluded when the lightest SUSY particle mass is below 400 (240) GeV and the mass splitting is larger than 400 (450) GeV. The sensitivity to high-mass wino and higgsino is significantly extended compared with the previous LHC searches using the other final states.

145 data tables

- - - - - - - - Overview of HEPData Record - - - - - - - - <br/><br/> <b>Cutflow:</b> <a href="104458?version=3&table=Cut flows for the representative signals">table</a><br/><br/> <b>Boson tagging:</b> <ul> <li><a href="104458?version=3&table=%24W%2FZ%5Crightarrow%20qq%24%20tagging%20efficiency">$W/Z\rightarrow qq$ tagging efficiency</a> <li><a href="104458?version=3&table=%24W%2FZ%5Crightarrow%20qq%24%20tagging%20rejection">$W/Z\rightarrow qq$ tagging rejection</a> <li><a href="104458?version=3&table=%24Z%2Fh%20%5Crightarrow%20bb%24%20tagging%20efficiency">$Z/h\rightarrow bb$ tagging efficiency</a> <li><a href="104458?version=3&table=%24Z%2Fh%20%5Crightarrow%20bb%24%20tagging%20rejection">$Z/h\rightarrow bb$ tagging rejection</a> <li><a href="104458?version=3&table=%24W%5Crightarrow%20qq%24%20tagging%20efficiency%20(vs%20official%20WP)">$W\rightarrow qq$ tagging efficiency (vs official WP)</a> <li><a href="104458?version=3&table=%24W%5Crightarrow%20qq%24%20tagging%20rejection%20(vs%20official%20WP)">$W\rightarrow qq$ tagging rejection (vs official WP)</a> <li><a href="104458?version=3&table=%24Z%5Crightarrow%20qq%24%20tagging%20efficiency%20(vs%20official%20WP)">$Z\rightarrow qq$ tagging efficiency (vs official WP)</a> <li><a href="104458?version=3&table=%24Z%5Crightarrow%20qq%24%20tagging%20rejection%20(vs%20official%20WP)">$Z\rightarrow qq$ tagging rejection (vs official WP)</a> </ul> <b>Systematic uncertainty:</b> <a href="104458?version=3&table=Total%20systematic%20uncertainties">table</a><br/><br/> <b>Summary of SR yields:</b> <a href="104458?version=3&table=Data%20yields%20and%20background%20expectation%20in%20the%20SRs">table</a><br/><br/> <b>Expected background yields and the breakdown:</b> <ul> <li><a href="104458?version=3&table=Data%20yields%20and%20background%20breakdown%20in%20SR">CR0L / SR</a> <li><a href="104458?version=3&table=Data%20yields%20and%20background%20breakdown%20in%20CR%2FVR%201L(1Y)">CR1L / VR1L /CR1Y / VR1Y</a> </ul> <b>SR distributions:</b> <ul> <li><a href="104458?version=3&table=Effective mass distribution in SR-4Q-VV">SR-4Q-VV: Effective mass</a> <li><a href="104458?version=3&table=Leading large-$R$ jet mass distribution in SR-4Q-VV">SR-4Q-VV: Leading jet mass</a> <li><a href="104458?version=3&table=Leading large-$R$ jet $D_{2}$ distribution in SR-4Q-VV">SR-4Q-VV: Leading jet $D_{2}$</a> <li><a href="104458?version=3&table=Sub-leading large-$R$ jet mass distribution in SR-4Q-VV">SR-4Q-VV: Sub-leading jet mass</a> <li><a href="104458?version=3&table=Sub-leading large-$R$ jet $D_{2}$ distribution in SR-4Q-VV">SR-4Q-VV: Sub-leading jet $D_{2}$</a> <li><a href="104458?version=3&table=$m_{T2}$ distribution in SR-2B2Q-VZ">SR-2B2Q-VZ: $m_{\textrm{T2}}$</a> <li><a href="104458?version=3&table=bb-tagged jet mass distribution in SR-2B2Q-VZ">SR-2B2Q-VZ: bb-tagged jet mass</a> <li><a href="104458?version=3&table=Effective mass distribution in SR-2B2Q-VZ">SR-2B2Q-VZ: Effective mass</a> <li><a href="104458?version=3&table=$m_{T2}$ distribution in SR-2B2Q-Vh">SR-2B2Q-Vh: $m_{\textrm{T2}}$</a> <li><a href="104458?version=3&table=bb-tagged jet mass distribution in SR-2B2Q-Vh">SR-2B2Q-Vh: bb-tagged jet mass</a> <li><a href="104458?version=3&table=Effective mass distribution in SR-2B2Q-Vh">SR-2B2Q-Vh: Effective mass</a> </ul> <b>Exclusion limit:</b> <ul> <li>$(\tilde{W},~\tilde{B})$-SIM model (C1C1-WW): <ul> <li><a href="104458?version=3&table=Exp limit on (W~, B~) simplified model (C1C1-WW)">Expected limit</a> <li><a href="104458?version=3&table=Exp%20limit%20(%2B1sig)%20on%20(W~, B~) simplified model (C1C1-WW)">Expected limit ($+1\sigma_{\textrm{exp}}$)</a> <li>Expected limit ($-1\sigma_{\textrm{exp}}$): (No mass point could be excluded) <li><a href="104458?version=3&table=Obs limit on (W~, B~) simplified model (C1C1-WW)">Observed limit</a> <li><a href="104458?version=3&table=Obs%20limit%20(%2B1sig)%20on%20(W~, B~) simplified model (C1C1-WW)">Observed limit ($+1\sigma_{\textrm{theory}}^{\textrm{SUSY}}$)</a> <li><a href="104458?version=3&table=Obs%20limit%20(-1sig)%20on%20(W~, B~) simplified model (C1C1-WW)">Observed limit ($-1\sigma_{\textrm{theory}}^{\textrm{SUSY}}$)</a> </ul> <li>$(\tilde{W},~\tilde{B})$-SIM model (C1N2-WZ): <ul> <li><a href="104458?version=3&table=Exp limit on (W~, B~) simplified model (C1N2-WZ)">Expected limit</a> <li><a href="104458?version=3&table=Exp%20limit%20(%2B1sig)%20on%20(W~, B~) simplified model (C1N2-WZ)">Expected limit ($+1\sigma_{\textrm{exp}}$)</a> <li><a href="104458?version=3&table=Exp%20limit%20(-1sig)%20on%20(W~, B~) simplified model (C1N2-WZ)">Expected limit ($-1\sigma_{\textrm{exp}}$)</a> <li><a href="104458?version=3&table=Obs limit on (W~, B~) simplified model (C1N2-WZ)">Observed limit</a> <li><a href="104458?version=3&table=Obs%20limit%20(%2B1sig)%20on%20(W~, B~) simplified model (C1N2-WZ)">Observed limit ($+1\sigma_{\textrm{theory}}^{\textrm{SUSY}}$)</a> <li><a href="104458?version=3&table=Obs%20limit%20(-1sig)%20on%20(W~, B~) simplified model (C1N2-WZ)">Observed limit ($-1\sigma_{\textrm{theory}}^{\textrm{SUSY}}$)</a> </ul> <li>$(\tilde{W},~\tilde{B})$-SIM model (C1N2-Wh): <ul> <li><a href="104458?version=3&table=Exp limit on (W~, B~) simplified model (C1N2-Wh)">Expected limit</a> <li><a href="104458?version=3&table=Exp%20limit%20(%2B1sig)%20on%20(W~, B~) simplified model (C1N2-Wh)">Expected limit ($+1\sigma_{\textrm{exp}}$)</a> <li><a href="104458?version=3&table=Exp%20limit%20(-1sig)%20on%20(W~, B~) simplified model (C1N2-Wh)">Expected limit ($-1\sigma_{\textrm{exp}}$)</a> <li><a href="104458?version=3&table=Obs limit on (W~, B~) simplified model (C1N2-Wh)">Observed limit</a> <li><a href="104458?version=3&table=Obs%20limit%20(%2B1sig)%20on%20(W~, B~) simplified model (C1N2-Wh)">Observed limit ($+1\sigma_{\textrm{theory}}^{\textrm{SUSY}}$)</a> <li><a href="104458?version=3&table=Obs%20limit%20(-1sig)%20on%20(W~, B~) simplified model (C1N2-Wh)">Observed limit ($-1\sigma_{\textrm{theory}}^{\textrm{SUSY}}$)</a> </ul> <li>$(\tilde{W},~\tilde{B})$ model ($\textrm{B}(\tilde{\chi}_{2}^{0}\rightarrow Z\tilde{\chi}_{1}^{0})=0\%$): <ul> <li><a href="104458?version=3&table=Exp limit on (W~, B~) B(N2->ZN1) = 0%">Expected limit</a> <li><a href="104458?version=3&table=Obs limit on (W~, B~) B(N2->ZN1) = 0%">Observed limit</a> </ul> <li>$(\tilde{W},~\tilde{B})$ model ($\textrm{B}(\tilde{\chi}_{2}^{0}\rightarrow Z\tilde{\chi}_{1}^{0})=25\%$): <ul> <li><a href="104458?version=3&table=Exp limit on (W~, B~) B(N2->ZN1) = 25%">Expected limit</a> <li><a href="104458?version=3&table=Obs limit on (W~, B~) B(N2->ZN1) = 25%">Observed limit</a> </ul> <li>$(\tilde{W},~\tilde{B})$ model ($\textrm{B}(\tilde{\chi}_{2}^{0}\rightarrow Z\tilde{\chi}_{1}^{0})=50\%$): <ul> <li><a href="104458?version=3&table=Exp limit on (W~, B~) B(N2->ZN1) = 50%">Expected limit</a> <li><a href="104458?version=3&table=Exp%20limit%20(%2B1sig)%20on%20(W~%2C%20B~)%20B(N2-%3EZN1)%20%3D%2050%25">Expected limit ($+1\sigma_{\textrm{exp}}$)</a> <li><a href="104458?version=3&table=Exp%20limit%20(-1sig)%20on%20(W~%2C%20B~)%20B(N2-%3EZN1)%20%3D%2050%25">Expected limit ($-1\sigma_{\textrm{exp}}$)</a> <li><a href="104458?version=3&table=Obs limit on (W~, B~) B(N2->ZN1) = 50%">Observed limit</a> <li><a href="104458?version=3&table=Obs%20limit%20(%2B1sig)%20on%20(W~%2C%20B~)%20B(N2-%3EZN1)%20%3D%2050%">Observed limit ($+1\sigma_{\textrm{theory}}^{\textrm{SUSY}}$)</a> <li><a href="104458?version=3&table=Obs%20limit%20(-1sig)%20on%20(W~%2C%20B~)%20B(N2-%3EZN1)%20%3D%2050%25">Observed limit ($-1\sigma_{\textrm{theory}}^{\textrm{SUSY}}$)</a> </ul> <li>$(\tilde{W},~\tilde{B})$ model ($\textrm{B}(\tilde{\chi}_{2}^{0}\rightarrow Z\tilde{\chi}_{1}^{0})=75\%$): <ul> <li><a href="104458?version=3&table=Exp limit on (W~, B~) B(N2->ZN1) = 75%">Expected limit</a> <li><a href="104458?version=3&table=Obs limit on (W~, B~) B(N2->ZN1) = 75%">Observed limit</a> </ul> <li>$(\tilde{W},~\tilde{B})$ model ($\textrm{B}(\tilde{\chi}_{2}^{0}\rightarrow Z\tilde{\chi}_{1}^{0})=100\%$): <ul> <li><a href="104458?version=3&table=Exp limit on (W~, B~) B(N2->ZN1) = 100%">Expected limit</a> <li><a href="104458?version=3&table=Obs limit on (W~, B~) B(N2->ZN1) = 100%">Observed limit</a> </ul> <li>$(\tilde{H},~\tilde{B})$ model ($\textrm{B}(\tilde{\chi}_{2}^{0}\rightarrow Z\tilde{\chi}_{1}^{0})=50\%$): <ul> <li><a href="104458?version=3&table=Exp limit on (H~, B~) B(N2->ZN1) = 50%">Expected limit</a> <li><a href="104458?version=3&table=Exp%20limit%20(%2B1sig)%20on%20(H~%2C%20B~)%20B(N2-%3EZN1)%20%3D%2050%25">Expected limit ($+1\sigma_{\textrm{exp}}$)</a> <li>Expected limit ($-1\sigma_{\textrm{exp}}$): (No mass point could be excluded) <li><a href="104458?version=3&table=Obs limit on (H~, B~) B(N2->ZN1) = 50%">Observed limit</a> <li><a href="104458?version=3&table=Obs%20limit%20(%2B1sig)%20on%20(H~%2C%20B~)%20B(N2-%3EZN1)%20%3D%2050%">Observed limit ($+1\sigma_{\textrm{theory}}^{\textrm{SUSY}}$)</a> <li><a href="104458?version=3&table=Obs%20limit%20(-1sig)%20on%20(H~%2C%20B~)%20B(N2-%3EZN1)%20%3D%2050%25">Observed limit ($-1\sigma_{\textrm{theory}}^{\textrm{SUSY}}$)</a> </ul> <li>$(\tilde{W},~\tilde{H})$ model ($\textrm{tan}\beta=10,~\mu>0$): <ul> <li><a href="104458?version=3&table=Exp limit on (W~, H~), tanb = 10, mu>0">Expected limit</a> <li><a href="104458?version=3&table=Exp%20limit%20(%2B1sig)%20on%20(W~%2C%20H~)%2C%20tanb%20%3D%2010%2C%20mu%3E0">Expected limit ($+1\sigma_{\textrm{exp}}$)</a> <li><a href="104458?version=3&table=Exp%20limit%20(-1sig)%20on%20(W~%2C%20H~)%2C%20tanb%20%3D%2010%2C%20mu%3E0">Expected limit ($-1\sigma_{\textrm{exp}}$)</a> <li><a href="104458?version=3&table=Obs limit on (W~, H~), tanb = 10, mu>0">Observed limit</a> <li><a href="104458?version=3&table=Obs%20limit%20(%2B1sig)%20on%20(W~%2C%20H~)%2C%20tanb%20%3D%2010%2C%20mu%3E0">Observed limit ($+1\sigma_{\textrm{theory}}^{\textrm{SUSY}}$)</a> <li><a href="104458?version=3&table=Obs%20limit%20(-1sig)%20on%20(W~%2C%20H~)%2C%20tanb%20%3D%2010%2C%20mu%3E0">Observed limit ($-1\sigma_{\textrm{theory}}^{\textrm{SUSY}}$)</a> </ul> <li>$(\tilde{H},~\tilde{W})$ model ($\textrm{tan}\beta=10,~\mu>0$): <ul> <li><a href="104458?version=3&table=Exp limit on (H~, W~), tanb = 10, mu>0">Expected limit</a> <li><a href="104458?version=3&table=Exp%20limit%20(%2B1sig)%20on%20(H~%2C%20W~)%2C%20tanb%20%3D%2010%2C%20mu%3E0">Expected limit ($+1\sigma_{\textrm{exp}}$)</a> <li>Expected limit ($-1\sigma_{\textrm{exp}}$): (No mass point could be excluded) <li><a href="104458?version=3&table=Obs limit on (H~, W~), tanb = 10, mu>0">Observed limit</a> <li><a href="104458?version=3&table=Obs%20limit%20(%2B1sig)%20on%20(H~%2C%20W~)%2C%20tanb%20%3D%2010%2C%20mu%3E0">Observed limit ($+1\sigma_{\textrm{theory}}^{\textrm{SUSY}}$)</a> <li><a href="104458?version=3&table=Obs%20limit%20(-1sig)%20on%20(H~%2C%20W~)%2C%20tanb%20%3D%2010%2C%20mu%3E0">Observed limit ($-1\sigma_{\textrm{theory}}^{\textrm{SUSY}}$)</a> </ul> <li>$(\tilde{W},~\tilde{H})$ model ($\textrm{tan}\beta=10$) on ($\mu$,$M_{2}$) plane: <ul> <li><a href="104458?version=3&table=Exp limit on (W~, H~), tanb = 10, M2 vs mu">Expected limit</a> <li><a href="104458?version=3&table=Exp%20limit%20(%2B1sig)%20on%20(W~%2C%20H~)%2C%20tanb%20%3D%2010%2C%20M2%20vs%20mu">Expected limit ($+1\sigma_{\textrm{exp}}$)</a> <li><a href="104458?version=3&table=Exp%20limit%20(-1sig)%20on%20(W~%2C%20H~)%2C%20tanb%20%3D%2010%2C%20M2%20vs%20mu">Expected limit ($-1\sigma_{\textrm{exp}}$)</a> <li><a href="104458?version=3&table=Obs limit on (W~, H~), tanb = 10, M2 vs mu">Observed limit</a> <li><a href="104458?version=3&table=Obs%20limit%20(%2B1sig)%20on%20(W~%2C%20H~)%2C%20tanb%20%3D%2010%2C%20M2%20vs%20mu">Observed limit ($+1\sigma_{\textrm{theory}}^{\textrm{SUSY}}$)</a> <li><a href="104458?version=3&table=Obs%20limit%20(-1sig)%20on%20(W~%2C%20H~)%2C%20tanb%20%3D%2010%2C%20M2%20vs%20mu">Observed limit ($-1\sigma_{\textrm{theory}}^{\textrm{SUSY}}$)</a> </ul> <li>$(\tilde{H},~\tilde{W})$ model ($\textrm{tan}\beta=10$) on ($\mu$,$M_{2}$) plane: <ul> <li><a href="104458?version=3&table=Exp limit on (H~, W~), tanb = 10, M2 vs mu">Expected limit</a> <li><a href="104458?version=3&table=Exp%20limit%20(%2B1sig)%20on%20(H~%2C%20W~)%2C%20tanb%20%3D%2010%2C%20M2%20vs%20mu">Expected limit ($+1\sigma_{\textrm{exp}}$)</a> <li>Expected limit ($-1\sigma_{\textrm{exp}}$): (No mass point could be excluded) <li><a href="104458?version=3&table=Obs limit on (H~, W~), tanb = 10, M2 vs mu">Observed limit</a> <li><a href="104458?version=3&table=Obs%20limit%20(%2B1sig)%20on%20(H~%2C%20W~)%2C%20tanb%20%3D%2010%2C%20M2%20vs%20mu">Observed limit ($+1\sigma_{\textrm{theory}}^{\textrm{SUSY}}$)</a> <li><a href="104458?version=3&table=Obs%20limit%20(-1sig)%20on%20(H~%2C%20W~)%2C%20tanb%20%3D%2010%2C%20M2%20vs%20mu">Observed limit ($-1\sigma_{\textrm{theory}}^{\textrm{SUSY}}$)</a> </ul> <li>$(\tilde{H},~\tilde{G})$ model: <ul> <li><a href="104458?version=3&table=Exp limit on (H~, G~)">Expected limit</a> <li><a href="104458?version=3&table=Exp%20limit%20(%2B1sig)%20on%20(H~%2C%20G~)">Expected limit ($+1\sigma_{\textrm{exp}}$)</a> <li><a href="104458?version=3&table=Exp%20limit%20(-1sig)%20on%20(H~%2C%20G~)">Expected limit ($-1\sigma_{\textrm{exp}}$)</a> <li><a href="104458?version=3&table=Obs limit on (H~, G~)">Observed limit</a> <li><a href="104458?version=3&table=Obs%20limit%20(%2B1sig)%20on%20(H~%2C%20G~)">Observed limit ($+1\sigma_{\textrm{theory}}^{\textrm{SUSY}}$)</a> <li><a href="104458?version=3&table=Obs%20limit%20(-1sig)%20on%20(H~%2C%20G~)">Observed limit ($-1\sigma_{\textrm{theory}}^{\textrm{SUSY}}$)</a> </ul> <li>$(\tilde{H},~\tilde{a})$ model ($\textrm{B}(\tilde{\chi}_{2}^{0}\rightarrow Z\tilde{a})=100\%$): <ul> <li><a href="104458?version=3&table=Exp limit on (H~, a~) B(N1->Za~) = 100%">Expected limit</a> <li><a href="104458?version=3&table=Exp%20limit%20(%2B1sig)%20on%20(H~%2C%20a~)%20B(N1-%3EZa~)%20%3D%20100%25">Expected limit ($+1\sigma_{\textrm{exp}}$)</a> <li><a href="104458?version=3&table=Exp%20limit%20(-1sig)%20on%20(H~%2C%20a~)%20B(N1-%3EZa~)%20%3D%20100%25">Expected limit ($-1\sigma_{\textrm{exp}}$)</a> <li><a href="104458?version=3&table=Obs limit on (H~, a~) B(N1->Za~) = 100%">Observed limit</a> <li><a href="104458?version=3&table=Obs%20limit%20(%2B1sig)%20on%20(H~%2C%20a~)%20B(N1-%3EZa~)%20%3D%20100%25">Observed limit ($+1\sigma_{\textrm{theory}}^{\textrm{SUSY}}$)</a> <li><a href="104458?version=3&table=Obs%20limit%20(-1sig)%20on%20(H~%2C%20a~)%20B(N1-%3EZa~)%20%3D%20100%">Observed limit ($-1\sigma_{\textrm{theory}}^{\textrm{SUSY}}$)</a> </ul> <li>$(\tilde{H},~\tilde{a})$ model ($\textrm{B}(\tilde{\chi}_{2}^{0}\rightarrow Z\tilde{a})=75\%$): <ul> <li><a href="104458?version=3&table=Exp limit on (H~, a~) B(N1->Za~) = 75%">Expected limit</a> <li><a href="104458?version=3&table=Obs limit on (H~, a~) B(N1->Za~) = 75%">Observed limit</a> </ul> <li>$(\tilde{H},~\tilde{a})$ model ($\textrm{B}(\tilde{\chi}_{2}^{0}\rightarrow Z\tilde{a})=50\%$): <ul> <li><a href="104458?version=3&table=Exp limit on (H~, a~) B(N1->Za~) = 50%">Expected limit</a> <li><a href="104458?version=3&table=Obs limit on (H~, a~) B(N1->Za~) = 50%">Observed limit</a> </ul> <li>$(\tilde{H},~\tilde{a})$ model ($\textrm{B}(\tilde{\chi}_{2}^{0}\rightarrow Z\tilde{a})=25\%$): <ul> <li>Expected limit : (No mass point could be excluded) <li><a href="104458?version=3&table=Obs limit on (H~, a~) B(N1->Za~) = 25%">Observed limit</a> </ul> </ul> <b>EWKino branching ratios:</b> <ul> <li>$(\tilde{W},~\tilde{H})$ model: <ul> <li><a href="104458?version=3&table=B(C2-%3EW%2BN1%2CN2)%20in%20(W~%2C%20H~)%2C%20tanb%3D10%2C%20mu%3E0">$\textrm{B}(\tilde{\chi}_{2}^{\pm}\rightarrow W\tilde{\chi}_{1,2}^{0})$</a> <li><a href="104458?version=3&table=B(C2-%3EZ%2BC1)%20in%20(W~%2C%20H~)%2C%20tanb=10%2C%20mu%3E0">$\textrm{B}(\tilde{\chi}_{2}^{\pm}\rightarrow Z\tilde{\chi}_{1}^{\pm})$</a> <li><a href="104458?version=3&table=B(C2-%3Eh%2BC1)%20in%20(W~%2C%20H~)%2C%20tanb=10%2C%20mu%3E0">$\textrm{B}(\tilde{\chi}_{2}^{\pm}\rightarrow h\tilde{\chi}_{1}^{\pm})$</a> <li><a href="104458?version=3&table=B(N3-%3EW%2BC1)%20in%20(W~%2C%20H~)%2C%20tanb=10%2C%20mu%3E0">$\textrm{B}(\tilde{\chi}_{3}^{0}\rightarrow W\tilde{\chi}_{1}^{\pm})$</a> <li><a href="104458?version=3&table=B(N3-%3EZ%2BN1%2CN2)%20in%20(W~%2C%20H~)%2C%20tanb%3D10%2C%20mu%3E0">$\textrm{B}(\tilde{\chi}_{3}^{0}\rightarrow Z\tilde{\chi}_{1,2}^{0})$</a> <li><a href="104458?version=3&table=B(N3-%3Eh%2BN1%2CN2)%20in%20(W~%2C%20H~)%2C%20tanb%3D10%2C%20mu%3E0">$\textrm{B}(\tilde{\chi}_{3}^{0}\rightarrow h\tilde{\chi}_{1,2}^{0})$</a> </ul> <li>$(\tilde{H},~\tilde{W})$ model: <ul> <li><a href="104458?version=3&table=B(C2-%3EW%2BN1)%20in%20(H~%2C%20W~)%2C%20tanb%3D10%2C%20mu%3E0">$\textrm{B}(\tilde{\chi}_{2}^{\pm}\rightarrow W\tilde{\chi}_{1}^{0})$</a> <li><a href="104458?version=3&table=B(C2-%3EZ%2BC1)%20in%20(H~%2C%20W~)%2C%20tanb%3D10%2C%20mu%3E0">$\textrm{B}(\tilde{\chi}_{2}^{\pm}\rightarrow Z\tilde{\chi}_{1}^{\pm})$</a> <li><a href="104458?version=3&table=B(C2-%3Eh%2BC1)%20in%20(H~%2C%20W~)%2C%20tanb%3D10%2C%20mu%3E0">$\textrm{B}(\tilde{\chi}_{2}^{\pm}\rightarrow h\tilde{\chi}_{1}^{\pm})$</a> <li><a href="104458?version=3&table=B(N2-%3EW%2BC1)%20in%20(H~%2C%20W~)%2C%20tanb%3D10%2C%20mu%3E0">$\textrm{B}(\tilde{\chi}_{2}^{0}\rightarrow W\tilde{\chi}_{1}^{\pm})$</a> <li><a href="104458?version=3&table=B(N2-%3EZ%2BN1)%20in%20(H~%2C%20W~)%2C%20tanb%3D10%2C%20mu%3E0">$\textrm{B}(\tilde{\chi}_{2}^{0}\rightarrow Z\tilde{\chi}_{1}^{0})$</a> <li><a href="104458?version=3&table=B(N2-%3Eh%2BN1)%20in%20(H~%2C%20W~)%2C%20tanb%3D10%2C%20mu%3E0">$\textrm{B}(\tilde{\chi}_{2}^{0}\rightarrow h\tilde{\chi}_{1}^{0})$</a> <li><a href="104458?version=3&table=B(N3-%3EW%2BC1)%20in%20(H~%2C%20W~)%2C%20tanb%3D10%2C%20mu%3E0">$\textrm{B}(\tilde{\chi}_{3}^{0}\rightarrow W\tilde{\chi}_{1}^{\pm})$</a> <li><a href="104458?version=3&table=B(N3-%3EZ%2BN1)%20in%20(H~%2C%20W~)%2C%20tanb%3D10%2C%20mu%3E0">$\textrm{B}(\tilde{\chi}_{3}^{0}\rightarrow Z\tilde{\chi}_{1}^{0})$</a> <li><a href="104458?version=3&table=B(N3-%3Eh%2BN1)%20in%20(H~%2C%20W~)%2C%20tanb%3D10%2C%20mu%3E0">$\textrm{B}(\tilde{\chi}_{3}^{0}\rightarrow h\tilde{\chi}_{1}^{0})$</a> </ul> </ul> <b>Cross-section upper limit:</b> <ul> <li>Expected: <ul> <li><a href="104458?version=3&table=Expected cross-section upper limit on C1C1-WW">$(\tilde{W},~\tilde{B})$-SIM model (C1C1-WW)</a> <li><a href="104458?version=3&table=Expected cross-section upper limit on C1N2-WZ">$(\tilde{W},~\tilde{B})$-SIM model (C1N2-WZ)</a> <li><a href="104458?version=3&table=Expected cross-section upper limit on C1N2-Wh">$(\tilde{W},~\tilde{B})$-SIM model (C1N2-Wh)</a> <li><a href="104458?version=3&table=Expected cross-section upper limit on (H~, G~)">$(\tilde{H},~\tilde{G})$ model</a> </ul> <li>Observed: <ul> <li><a href="104458?version=3&table=Observed cross-section upper limit on C1C1-WW">$(\tilde{W},~\tilde{B})$-SIM model (C1C1-WW)</a> <li><a href="104458?version=3&table=Observed cross-section upper limit on C1N2-WZ">$(\tilde{W},~\tilde{B})$-SIM model (C1N2-WZ)</a> <li><a href="104458?version=3&table=Observed cross-section upper limit on C1N2-Wh">$(\tilde{W},~\tilde{B})$-SIM model (C1N2-Wh)</a> <li><a href="104458?version=3&table=Observed cross-section upper limit on (H~, G~)">$(\tilde{H},~\tilde{G})$ model</a> </ul> </ul> <b>Acceptance:</b> <ul> <li><a href="104458?version=3&table=Acceptance of C1C1-WW signals by SR-4Q-VV">$(\tilde{W},~\tilde{B})$-SIM model (C1C1-WW) in SR-4Q-VV</a> <li><a href="104458?version=3&table=Acceptance of C1N2-WZ signals by SR-4Q-VV">$(\tilde{W},~\tilde{B})$-SIM model (C1N2-WZ) in SR-4Q-VV</a> <li><a href="104458?version=3&table=Acceptance of C1N2-WZ signals by SR-2B2Q-VZ">$(\tilde{W},~\tilde{B})$-SIM model (C1N2-WZ) in SR-2B2Q-VZ</a> <li><a href="104458?version=3&table=Acceptance of C1N2-Wh signals by SR-2B2Q-Vh">$(\tilde{W},~\tilde{B})$-SIM model (C1N2-WZ) in SR-2B2Q-Vh</a> <li><a href="104458?version=3&table=Acceptance of N2N3-ZZ signals by SR-4Q-VV">$(\tilde{H},~\tilde{B})$-SIM model (N2N3-ZZ) in SR-4Q-VV</a> <li><a href="104458?version=3&table=Acceptance of N2N3-ZZ signals by SR-2B2Q-VZ">$(\tilde{H},~\tilde{B})$-SIM model (N2N3-ZZ) in SR-2B2Q-VZ</a> <li><a href="104458?version=3&table=Acceptance of N2N3-Zh signals by SR-2B2Q-Vh">$(\tilde{H},~\tilde{B})$-SIM model (N2N3-Zh) in SR-2B2Q-Vh</a> <li><a href="104458?version=3&table=Acceptance of N2N3-hh signals by SR-2B2Q-Vh">$(\tilde{H},~\tilde{B})$-SIM model (N2N3-hh) in SR-2B2Q-Vh</a> <li><a href="104458?version=3&table=Acceptance of (H~, G~) signals by SR-4Q-VV">$(\tilde{H},~\tilde{G})$ model in SR-4Q-VV</a> <li><a href="104458?version=3&table=Acceptance of (H~, G~) signals by SR-2B2Q-VZ">$(\tilde{H},~\tilde{G})$ model in SR-2B2Q-VZ</a> <li><a href="104458?version=3&table=Acceptance of (H~, G~) signals by SR-2B2Q-Vh">$(\tilde{H},~\tilde{G})$ model in SR-2B2Q-Vh</a> </ul> <b>Efficiency:</b> <ul> <li><a href="104458?version=3&table=Efficiency of C1C1-WW signals by SR-4Q-VV">$(\tilde{W},~\tilde{B})$-SIM model (C1C1-WW) in SR-4Q-VV</a> <li><a href="104458?version=3&table=Efficiency of C1N2-WZ signals by SR-4Q-VV">$(\tilde{W},~\tilde{B})$-SIM model (C1N2-WZ) in SR-4Q-VV</a> <li><a href="104458?version=3&table=Efficiency of C1N2-WZ signals by SR-2B2Q-VZ">$(\tilde{W},~\tilde{B})$-SIM model (C1N2-WZ) in SR-2B2Q-VZ</a> <li><a href="104458?version=3&table=Efficiency of C1N2-Wh signals by SR-2B2Q-Vh">$(\tilde{W},~\tilde{B})$-SIM model (C1N2-Wh) in SR-2B2Q-Vh</a> <li><a href="104458?version=3&table=Efficiency of N2N3-ZZ signals by SR-4Q-VV">$(\tilde{H},~\tilde{B})$-SIM model (N2N3-ZZ) in SR-4Q-VV</a> <li><a href="104458?version=3&table=Efficiency of N2N3-ZZ signals by SR-2B2Q-VZ">$(\tilde{H},~\tilde{B})$-SIM model (N2N3-ZZ) in SR-2B2Q-VZ</a> <li><a href="104458?version=3&table=Efficiency of N2N3-Zh signals by SR-2B2Q-Vh">$(\tilde{H},~\tilde{B})$-SIM model (N2N3-Zh) in SR-2B2Q-Vh</a> <li><a href="104458?version=3&table=Efficiency of N2N3-hh signals by SR-2B2Q-Vh">$(\tilde{H},~\tilde{B})$-SIM model (N2N3-hh) in SR-2B2Q-Vh</a> <li><a href="104458?version=3&table=Efficiency of (H~, G~) signals by SR-4Q-VV">$(\tilde{H},~\tilde{G})$ model in SR-4Q-VV</a> <li><a href="104458?version=3&table=Efficiency of (H~, G~) signals by SR-2B2Q-VZ">$(\tilde{H},~\tilde{G})$ model in SR-2B2Q-VZ</a> <li><a href="104458?version=3&table=Efficiency of (H~, G~) signals by SR-2B2Q-Vh">$(\tilde{H},~\tilde{G})$ model in SR-2B2Q-Vh</a> </ul>

Cut flows of some representative signals up to SR-4Q-VV, SR-2B2Q-VZ, and SR-2B2Q-Vh. One signal point from the $(\tilde{W},~\tilde{B})$ simplified models (C1C1-WW, C1N2-WZ, and C1N2-Wh) and $(\tilde{H},~\tilde{G})$ is chosen. The "preliminary event reduction" is a technical selection applied for reducing the sample size, which is fully efficient after the $n_{\textrm{Large}-R~\textrm{jets}}\geq 2$ selection.

The boson-tagging efficiency for jets arising from $W/Z$ bosons decaying into $q\bar{q}$ (signal jets) are shown. The signal jet efficiency of $W_{qq}$/$Z_{qq}$-tagging is evaluated using a sample of pre-selected large-$R$ jets ($p_{\textrm{T}}>200~\textrm{GeV}, |\eta|<2.0, m_{J} > 40~\textrm{GeV}$) in the simulated $(\tilde{W},\tilde{B})$ simplified model signal events with $\Delta m (\tilde{\chi}_{\textrm{heavy}},~\tilde{\chi}_{\textrm{light}}) \ge 400~\textrm{GeV}$. The jets are matched with generator-level $W/Z$-bosons by $\Delta R<1.0$ which decay into $q\bar{q}$. The efficiency correction factors are applied on the signal efficiency rejection for the $W_{qq}$/$Z_{qq}$-tagging. The systematic uncertainty is represented by the hashed bands.

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Version 4
Search for Higgs boson pair production in the two bottom quarks plus two photons final state in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Braden Keim ; Abbott, Dale ; et al.
Phys.Rev.D 106 (2022) 052001, 2022.
Inspire Record 1995886 DOI 10.17182/hepdata.105864

Searches are performed for nonresonant and resonant di-Higgs boson production in the $b\bar{b}\gamma\gamma$ final state. The data set used corresponds to an integrated luminosity of 139 fb$^{-1}$ of proton-proton collisions at a center-of-mass energy of 13 TeV recorded by the ATLAS detector at the CERN Large Hadron Collider. No excess above the expected background is found and upper limits on the di-Higgs boson production cross sections are set. A 95% confidence-level upper limit of 4.2 times the cross section predicted by the Standard Model is set on $pp \rightarrow HH$ nonresonant production, where the expected limit is 5.7 times the Standard Model predicted value. The expected constraints are obtained for a background hypothesis excluding $pp \rightarrow HH$ production. The observed (expected) constraints on the Higgs boson trilinear coupling modifier $\kappa_{\lambda}$ are determined to be $[-1.5, 6.7]$ $([-2.4, 7.7])$ at 95% confidence level, where the expected constraints on $\kappa_{\lambda}$ are obtained excluding $pp \rightarrow HH$ production from the background hypothesis. For resonant production of a new hypothetical scalar particle $X$ ($X \rightarrow HH \rightarrow b\bar{b}\gamma\gamma$), limits on the cross section for $pp \to X \to HH$ are presented in the narrow-width approximation as a function of $m_{X}$ in the range $251 \leq m_{X} \leq 1000$ GeV. The observed (expected) limits on the cross section for $pp \to X \to HH$ range from 640 fb to 44 fb (391 fb to 46 fb) over the considered mass range.

124 data tables

The BDT distribution of the di-Higgs ggF signal for two different values of $\kappa_{\lambda}$ and the main backgrounds in the low mass region ($m^{*}_{b\bar{b}\gamma\gamma} < 350$ GeV). Distributions are normalized to unit area. The dotted lines denote the category boundaries. Events with a BDT score below 0.881 in the low mass region are discarded.

The BDT distribution of the di-Higgs ggF signal for two different values of $\kappa_{\lambda}$ and the main backgrounds in the low mass region ($m^{*}_{b\bar{b}\gamma\gamma} < 350$ GeV). Distributions are normalized to unit area. The dotted lines denote the category boundaries. Events with a BDT score below 0.881 in the low mass region are discarded.

The BDT distribution of the di-Higgs ggF signal for two different values of $\kappa_{\lambda}$ and the main backgrounds in the low mass region ($m^{*}_{b\bar{b}\gamma\gamma} < 350$ GeV). Distributions are normalized to unit area. The dotted lines denote the category boundaries. Events with a BDT score below 0.881 in the low mass region are discarded.

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Search for single production of a vector-like $T$ quark decaying into a Higgs boson and top quark with fully hadronic final states using the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Braden Keim ; Abbott, Dale ; et al.
Phys.Rev.D 105 (2022) 092012, 2022.
Inspire Record 2013051 DOI 10.17182/hepdata.131522

A search is made for a vector-like $T$ quark decaying into a Higgs boson and a top quark in 13 TeV proton-proton collisions using the ATLAS detector at the Large Hadron Collider with a data sample corresponding to an integrated luminosity of 139 fb$^{-1}$. The Higgs-boson and top-quark candidates are identified in the all-hadronic decay mode, where $H\to b\bar{b}$ and $t\to b W \to b q \bar{q}^\prime$ are reconstructed as large-radius jets. The candidate Higgs boson, top quark, and associated B-hadrons are identified using tagging algorithms. No significant excess is observed above the background, so limits are set on the production cross-section of a singlet $T$ quark at 95% confidence level, depending on the mass, $m_T$, and coupling, $\kappa_T$, of the vector-like $T$ quark to Standard Model particles. In the considered mass range between 1.0 and 2.3 TeV, the upper limit on the allowed coupling values increases with $m_T$ from a minimum value of 0.35 for 1.07 < $m_T$ < 1.4 TeV to 1.6 for $m_T$ = 2.3 TeV.

8 data tables

Dijet invariant mass distribution for the $SR$ showing the results of the model when fitted to the data. A $T$-quark hypothesis with $m_{T} = 1.6$ TeV and $\kappa_{T} = 0.5$ is used in the fit.

Dijet invariant mass distribution for the $ttNR$ showing the results of the model when fitted to the data. A $T$-quark hypothesis with $m_{T} = 1.6$ TeV and $\kappa_{T} = 0.5$ is used in the fit.

Observed and expected 95% CL upper limits on the single $T$-quark coupling $\kappa_{T}$ as a function of $m_{T}$ are shown.

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Search for flavor-changing neutral-current couplings between the top quark and the $Z$ boson with LHC Run 2 proton-proton collisions at $\sqrt{s} = 13$ TeV with the ATLAS detector

The ATLAS collaboration Aad, G. ; Abbott, B. ; Abbott, D.C. ; et al.
Phys.Rev.D 108 (2023) 032019, 2023.
Inspire Record 2627201 DOI 10.17182/hepdata.145074

A search for flavor-changing neutral-current couplings between a top quark, an up or charm quark and a $Z$ boson is presented, using proton-proton collision data at $\sqrt{s} = 13$ TeV collected by the ATLAS detector at the Large Hadron Collider. The analyzed dataset corresponds to an integrated luminosity of 139 fb$^{-1}$. The search targets both single-top-quark events produced as $gq\rightarrow tZ$ (with $q = u, c$) and top-quark-pair events, with one top quark decaying through the $t \rightarrow Zq$ channel. The analysis considers events with three leptons (electrons or muons), a $b$-tagged jet, possible additional jets, and missing transverse momentum. The data are found to be consistent with the background-only hypothesis and 95% confidence-level limits on the $t \rightarrow Zq$ branching ratios are set, assuming only tensor operators of the Standard Model effective field theory framework contribute to the $tZq$ vertices. These are $6.2 \times 10^{-5}$ ($13\times 10^{-5}$) for $t\rightarrow Zu$ ($t\rightarrow Zc$) for a left-handed $tZq$ coupling, and $6.6 \times 10^{-5}$ ($12\times 10^{-5}$) in the case of a right-handed coupling. These results are interpreted as 95% CL upper limits on the strength of corresponding couplings, yielding limits for $|C_{uW}^{(13)*}|$ and $|C_{uB}^{(13)*}|$ ($|C_{uW}^{(31)}|$ and $|C_{uB}^{(31)}|$) of 0.15 (0.16), and limits for $|C_{uW}^{(23)*}|$ and $|C_{uB}^{(23)*}|$ ($|C_{uW}^{(32)}|$ and $|C_{uB}^{(32)}|$) of 0.22 (0.21), assuming a new-physics energy scale $\Lambda_\text{NP}$ of 1 TeV.

18 data tables

Summary of the signal strength $\mu$ parameters obtained from the fits to extract LH and RH results for the FCNC tZu and tZc couplings. For the reference branching ratio, the most stringent limits are used.

Observed and expected 95% CL limits on the FCNC $t\rightarrow Zq$ branching ratios and the effective coupling strengths for different vertices and couplings (top eight rows). For the latter, the energy scale is assumed to be $\Lambda_{NP}$ = 1 TeV. The bottom rows show, for the case of the FCNC $t\rightarrow Zu$ branching ratio, the observed and expected 95% CL limits when only one of the two SRs, either SR1 or SR2, and all CRs are included in the likelihood.

Comparison between data and background prediction before the fit (Pre-Fit) for the mass of the SM top-quark candidate in SR1. The uncertainty band includes both the statistical and systematic uncertainties in the background prediction. The four FCNC LH signals are also shown separately, normalized to five times the cross-section corresponding to the most stringent observed branching ratio limits. The first (last) bin in all distributions includes the underflow (overflow). The lower panels show the ratios of the data (Data) to the background prediction (Bkg.).

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Search for heavy particles in the $b$-tagged dijet mass distribution with additional $b$-tagged jets in proton-proton collisions at $\sqrt{s} = 13$ TeV with the ATLAS experiment

The ATLAS collaboration Aad, Georges ; Abbott, Braden Keim ; Abbott, Dale ; et al.
Phys.Rev.D 105 (2022) 012001, 2022.
Inspire Record 1909506 DOI 10.17182/hepdata.111056

A search optimized for new heavy particles decaying to two $b$-quarks and produced in association with additional $b$-quarks is reported. The sensitivity is improved by $b$-tagging at least one lower-$p_{\rm{T}}$ jet in addition to the two highest-$p_{\rm{T}}$ jets. The data used in this search correspond to an integrated luminosity of 103 $\text{fb}^{-1}$ collected with a dedicated trijet trigger during the 2017 and 2018 $\sqrt{s} = 13$ TeV proton-proton collision runs with the ATLAS detector at the LHC. The search looks for resonant peaks in the $b$-tagged dijet invariant mass spectrum over a smoothly falling background. The background is estimated with an innovative data-driven method based on orthonormal functions. The observed $b$-tagged dijet invariant mass spectrum is compatible with the background-only hypothesis. Upper limits at 95% confidence level on a heavy vector-boson production cross section times branching ratio to a pair of $b$-quarks are derived.

4 data tables

Background estimate from the FD method with N=3 and data in the SR.

The observed (solid) and expected (dashed) 95% CL upper limits on the production of $Z' \to b\bar{b}$ in association with b-quarks.

Acceptance and Acceptance times efficiency for the LUV Z' model.

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Search for heavy neutral leptons in decays of $W$ bosons using a dilepton displaced vertex in $\sqrt{s}=13$ TeV $pp$ collisions with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Braden Keim ; Abbott, D.C. ; et al.
Phys.Rev.Lett. 131 (2023) 061803, 2023.
Inspire Record 2072355 DOI 10.17182/hepdata.115511

A search for a long-lived, heavy neutral lepton ($\mathcal{N}$) in 139 fb$^{-1}$ of $\sqrt{s}=13$ TeV $pp$ collision data collected by the ATLAS detector at the Large Hadron Collider is reported. The $\mathcal{N}$ is produced via $W \rightarrow \mathcal{N} \mu$ or $W \rightarrow \mathcal{N} e$ and decays into two charged leptons and a neutrino, forming a displaced vertex. The $\mathcal{N}$ mass is used to discriminate between signal and background. No signal is observed, and limits are set on the squared mixing parameters of the $\mathcal{N}$ with the left-handed neutrino states for the $\mathcal{N}$ mass range $3$ GeV $< m_{\mathcal{N}} < 15$ GeV. For the first time, limits are given for both single-flavor and multiflavor mixing scenarios motivated by neutrino flavor oscillation results for both the normal and inverted neutrino-mass hierarchies.

29 data tables

Expected and observed 95% CL for the 1SFH e Dirac model.

Expected and observed 95% CL for the 1SFH e Majorana model.

Expected and observed 95% CL for the 1SFH mu Dirac model.

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