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.
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.
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.
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.
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.
- - - - - - - - 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.
We report the first multi-differential measurements of strange hadrons of $K^{-}$, $\phi$ and $\Xi^{-}$ yields as well as the ratios of $\phi/K^-$ and $\phi/\Xi^-$ in Au+Au collisions at ${\sqrt{s_{\rm NN}} = \rm{3\,GeV}}$ with the STAR experiment fixed target configuration at RHIC. The $\phi$ mesons and $\Xi^{-}$ hyperons are measured through hadronic decay channels, $\phi\rightarrow K^+K^-$ and $\Xi^-\rightarrow \Lambda\pi^-$. Collision centrality and rapidity dependence of the transverse momentum spectra for these strange hadrons are presented. The $4\pi$ yields and ratios are compared to thermal model and hadronic transport model predictions. At this collision energy, thermal model with grand canonical ensemble (GCE) under-predicts the $\phi/K^-$ and $\phi/\Xi^-$ ratios while the result of canonical ensemble (CE) calculations reproduce $\phi/K^-$, with the correlation length $r_c \sim 2.7$ fm, and $\phi/\Xi^-$, $r_c \sim 4.2$ fm, for the 0-10% central collisions. Hadronic transport models including high mass resonance decays could also describe the ratios. While thermal calculations with GCE work well for strangeness production in high energy collisions, the change to CE at $\rm{3\,GeV}$ implies a rather different medium property at high baryon density.
$K^-$ (a), invariant yields as a function of $m_T-m_0$ for various rapidity regions in 0--10\% central Au+Au collisions at ${\sqrt{s_{\mathrm{NN}}} = \mathrm{3\,GeV}}$. Statistics and systematic uncertainties are added quadratic here for plotting. Solid and dashed black lines depict $m_T$ exponential function fits to the measured data points with arbitrate scaling factors in each rapidity windows.
$\phi$ meson (b) invariant yields as a function of $m_T-m_0$ for various rapidity regions in 0--10\% central Au+Au collisions at ${\sqrt{s_{\mathrm{NN}}} = \mathrm{3\,GeV}}$. Statistics and systematic uncertainties are added quadratic here for plotting. Solid and dashed black lines depict $m_T$ exponential function fits to the measured data points with arbitrate scaling factors in each rapidity windows.
$\Xi^-$ (c) invariant yields as a function of $m_T-m_0$ for various rapidity regions in 0--10\% central Au+Au collisions at ${\sqrt{s_{\mathrm{NN}}} = \mathrm{3\,GeV}}$. Statistics and systematic uncertainties are added quadratic here for plotting. Solid and dashed black lines depict $m_T$ exponential function fits to the measured data points with arbitrate scaling factors in each rapidity windows.
We report on the measurements of directed flow $v_1$ and elliptic flow $v_2$ for hadrons ($\pi^{\pm}$, $K^{\pm}$, $K_{S}^0$, $p$, $\phi$, $\Lambda$ and $\Xi^{-}$) from Au+Au collisions at $\sqrt{s_{NN}}$ = 3 GeV and $v_{2}$ for ($\pi^{\pm}$, $K^{\pm}$, $p$ and $\overline{p}$) at 27 and 54.4 GeV with the STAR experiment. While at the two higher energy midcentral collisions the number-of-constituent-quark (NCQ) scaling holds, at 3 GeV the $v_{2}$ at midrapidity is negative for all hadrons and the NCQ scaling is absent. In addition, the $v_1$ slopes at midrapidity for almost all observed hadrons are found to be positive, implying dominant repulsive baryonic interactions. The features of negative $v_2$ and positive $v_1$ slope at 3 GeV can be reproduced with a baryonic mean-field in transport model calculations. These results imply that the medium in such collisions is likely characterized by baryonic interactions.
Event plane resolution as a function of collision centrality from Au+Au collisions at $\sqrt{s_{NN}}$=3 (a), 27 and 54.4 GeV (b). In case of the 3 GeV collisions, $\Psi_{1}$ is used to determine the event plane resolutions for the first and second harmonic coefficients shown as $R_{11}$ and $R_{12}$ in left panel. In the 27 and 54.4 GeV collisions, $\Psi_{2}$ is used to evaluate the second order event plane resolution, see right panel. In all cases, the statistic uncertainties are smaller than symbol sizes.
Rapidity($y$) dependence of $v_1$ (top panels) and $v_2$ (bottom panels) of proton and $\Lambda$ baryons (left panels), pions (middle panels) and kaons (right panels) in 10-40% centrality for the $\sqrt{s_{NN}}$ = 3GeV Au+Au collisions. Statistical and systematic uncertainties are shown as bars and gray bands, respectively. Some uncertainties are smaller than the data points. The UrQMD and JAM results are shown as bands:golden, red and blue bands stand for JAM mean-field, UrQMD mean-field and UrQMD cascade mode, respectively. The value of the incompressibility $\kappa$ = 380 MeV is used in the mean-field option. More detailed model descriptions and data comparisons can be found in Supplemental Material.
Rapidity($y$) dependence of $v_1$ (top panels) and $v_2$ (bottom panels) of proton and $\Lambda$ baryons (left panels), pions (middle panels) and kaons (right panels) in 10-40% centrality for the $\sqrt{s_{NN}}$ = 3GeV Au+Au collisions. Statistical and systematic uncertainties are shown as bars and gray bands, respectively. Some uncertainties are smaller than the data points. The UrQMD and JAM results are shown as bands:golden, red and blue bands stand for JAM mean-field, UrQMD mean-field and UrQMD cascade mode, respectively. The value of the incompressibility $\kappa$ = 380 MeV is used in the mean-field option. More detailed model descriptions and data comparisons can be found in Supplemental Material.
Global hyperon polarization, $\overline{P}_\mathrm{H}$, in Au+Au collisions over a large range of collision energy, $\sqrt{s_\mathrm{NN}}$, was recently measured and successfully reproduced by hydrodynamic and transport models with intense fluid vorticity of the quark-gluon plasma. While naïve extrapolation of data trends suggests a large $\overline{P}_\mathrm{H}$ as the collision energy is reduced, the behavior of $\overline{P}_\mathrm{H}$ at small $\sqrt{s_\mathrm{NN}}<7.7$ GeV is unknown. Operating the STAR experiment in fixed-target mode, we measured the polarization of $\Lambda$ hyperons along the direction of global angular momentum in Au+Au collisions at $\sqrt{s_\mathrm{NN}}=3$ GeV. The observation of substantial polarization of $4.91\pm0.81(\rm stat.)\pm0.15(\rm syst.)$% in these collisions may require a reexamination of the viscosity of any fluid created in the collision, of the thermalization timescale of rotational modes, and of hadronic mechanisms to produce global polarization.
The measured invariant-mass distributions of two classes of $\Lambda$-hyperon decays. The decay classes are defined using the scalar triple product $\left(\vec{p}_\Lambda\times\vec{p}_p^*\right)\cdot \vec{B}_{\rm STAR}$, which is positive for right decays and negative for left decays. The right decay class has a notably sharper invariant-mass distribution than the left decay class, and this is due to the effects of daughter tracks crossing in the STAR TPC with the STAR magnetic field anti-parallel to the lab frame's z direction. The opposite pattern is obtained by flipping the sign of the STAR magnetic field or by reconstructing $\bar{\Lambda}$ hyperons.
The signal polarizations extracted according to the restricted invariant-mass method as a function of $\phi_\Lambda - \phi_p^*$, for positive-rapidity $\Lambda$ hyperons. The sinusoidal behavior is driven by non-zero net $v_1$. The vertical shift corresponds to the vorticity-driven polarization; in collider mode, where the net $v_1$ is zero, this dependence on $\phi_\Lambda - \phi_p^*$ does not exist.
The integrated Global $\Lambda$-hyperon Polarization in mid-central collisions at $\sqrt{s_{\rm NN}}=3$ GeV. The trend of increasing $\overline{P}_{\rm H}$ with decreasing $\sqrt{s_{\rm NN}}$ is maintained at this low collision energy. Previous experimental results are scaled by the updated $\Lambda$-hyperon decay parameter $\alpha_\Lambda=0.732$ for comparison with this result. Recent model calculations extended to low collision energy show disagreement between our data and AMPT and rough agreement with the 3-Fluid Dynamics (3FD) model. Previous measurements shown alongside our data can be found at: https://www.hepdata.net/record/ins750410?version=2; https://www.hepdata.net/record/ins1510474?version=1; https://www.hepdata.net/record/ins1672785?version=2; https://www.hepdata.net/record/ins1752507?version=2.
The first measurements of differential branching fractions of inclusive semileptonic ${B \to X_u \, \ell^+\, \nu_{\ell}}$ decays are performed using the full Belle data set of 711 fb$^{-1}$ of integrated luminosity at the $\Upsilon(4S)$ resonance and for $\ell = e, \mu$. Differential branching fractions are reported as a function of the lepton momentum, the four-momentum-transfer squared, light-cone momenta, the hadronic mass, and the hadronic mass squared. They are obtained by subtracting the backgrounds from semileptonic ${B \to X_c \, \ell^+\, \nu_{\ell}}$ decays and other processes, and corrected for resolution and acceptance effects. The measured distributions are compared to predictions from inclusive and hybrid ${B \to X_u \, \ell^+\, \nu_{\ell}}$ calculations.
The measured differential branching fractions as a function of the lepton energy in the $B$ rest frame ($E_\ell^B$).
The measured differential branching fractions as a function of the four-momentum-transfer squared of the $B$ to the $X_u$ system $q^{2}$.
The measured differential branching fractions as a function of the invariant hadronic mass of the $X_u$ system ($M_X$).
A measurement of prompt photon-pair production in proton-proton collisions at $\sqrt{s}=13$ TeV is presented. The data were recorded by the ATLAS detector at the LHC with an integrated luminosity of 139 fb$^{-1}$. Events with two photons in the well-instrumented region of the detector are selected. The photons are required to be isolated and have a transverse momentum of $p_\mathrm{T,\gamma_{1(2)}} > 40(30)$ GeV for the leading (sub-leading) photon. The differential cross sections as functions of several observables for the diphoton system are measured and compared with theoretical predictions from state-of-the-art Monte Carlo and fixed-order calculations. The QCD predictions from next-to-next-to-leading-order calculations and multi-leg merged calculations are able to describe the measured integrated and differential cross sections within uncertainties, whereas lower-order calculations show significant deviations, demonstrating that higher-order perturbative QCD corrections are crucial for this process. The resummed predictions with parton showers additionally provide an excellent description of the low transverse-momentum regime of the diphoton system.
Differential cross section as a function of $p_{T,\gamma_{1}}$. The table contains the values measured in data and theory predictions from SHERPA, DIPHOX and NNLOJET.
Differential cross section as a function of $p_{T,\gamma_{2}}$. The table contains the values measured in data and theory predictions from SHERPA, DIPHOX and NNLOJET.
Integrated fiducial cross section measured in data and from different predictions.
A novel search for exotic decays of the Higgs boson into pairs of long-lived neutral particles, each decaying into a bottom quark pair, is performed using 139 fb$^{-1}$ of $\sqrt{s} = 13$ TeV proton-proton collision data collected with the ATLAS detector at the LHC. Events consistent with the production of a Higgs boson in association with a leptonically decaying $Z$ boson are analysed. Long-lived particle (LLP) decays are reconstructed from inner-detector tracks as displaced vertices with high mass and track multiplicity relative to Standard Model processes. The analysis selection requires the presence of at least two displaced vertices, effectively suppressing Standard Model backgrounds. The residual background contribution is estimated using a data-driven technique. No excess over Standard Model predictions is observed, and upper limits are set on the branching ratio of the Higgs boson to LLPs. Branching ratios above 10% are excluded at 95% confidence level for LLP mean proper lifetimes $c\tau$ as small as 4 mm and as large as 100 mm. For LLP masses below 40 GeV, these results represent the most stringent constraint in this lifetime regime.
95% CL exclusion limits on $\mathcal{B}(H\rightarrow aa \rightarrow b\bar{b}b\bar{b})$ for $m_a = 16$ GeV.
95% CL exclusion limits on $\mathcal{B}(H\rightarrow aa \rightarrow b\bar{b}b\bar{b})$ for $m_a = 25$ GeV.
95% CL exclusion limits on $\mathcal{B}(H\rightarrow aa \rightarrow b\bar{b}b\bar{b})$ for $m_a = 35$ GeV.
A measurement of four-top-quark production using proton-proton collision data at a centre-of-mass energy of 13 TeV collected by the ATLAS detector at the Large Hadron Collider corresponding to an integrated luminosity of 139 fb$^{-1}$ is presented. Events are selected if they contain a single lepton (electron or muon) or an opposite-sign lepton pair, in association with multiple jets. The events are categorised according to the number of jets and how likely these are to contain $b$-hadrons. A multivariate technique is then used to discriminate between signal and background events. The measured four-top-quark production cross section is found to be 26$^{+17}_{-15}$ fb, with a corresponding observed (expected) significance of 1.9 (1.0) standard deviations over the background-only hypothesis. The result is combined with the previous measurement performed by the ATLAS Collaboration in the multilepton final state. The combined four-top-quark production cross section is measured to be 24$^{+7}_{-6}$ fb, with a corresponding observed (expected) signal significance of 4.7 (2.6) standard deviations over the background-only predictions. It is consistent within 2.0 standard deviations with the Standard Model expectation of 12.0$\pm$2.4 fb.
The results of the fitted signal strength $\mu$ in the 1L/2LOS channel
The results of fitted inclusive ${t\bar{t}t\bar{t}}$ cross-section in the 1L/2LOS channel
Ranking of the nuisance parameters included in the fit according to their impact on the signal strength $\mu$. The impact of each nuisance parameter, $\Delta\mu$, is computed by comparing the nominal best-fit value of $\mu$ with the result of the fit when fixing the nuisance parameter to its best-fit value, $\hat{\theta}$, shifted by its pre-fit (post-fit) uncertainties $\pm \Delta\theta$ ($\pm \Delta\hat{\theta}$).