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.
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 $\pm \Delta\theta$ ($\pm \Delta\hat{\theta}$).
A search for heavy resonances decaying into a pair of $Z$ bosons leading to $\ell^+\ell^-\ell'^+\ell'^-$ and $\ell^+\ell^-\nu\bar\nu$ final states, where $\ell$ stands for either an electron or a muon, is presented. The search uses proton-proton collision data at a centre-of-mass energy of 13 TeV collected from 2015 to 2018 that corresponds to the full integrated luminosity of 139 fb$^{-1}$ recorded by the ATLAS detector during Run 2 of the Large Hadron Collider. Different mass ranges spanning 200 GeV to 2000 GeV for the hypothetical resonances are considered, depending on the final state and model. In the absence of a significant observed excess, the results are interpreted as upper limits on the production cross section of a spin-0 or spin-2 resonance. The upper limits for the spin-0 resonance are translated to exclusion contours in the context of Type-I and Type-II two-Higgs-doublet models, and the limits for the spin-2 resonance are used to constrain the Randall--Sundrum model with an extra dimension giving rise to spin-2 graviton excitations.
Distribution of the four-lepton invariant mass in the four-lepton final state for the ggF-MVA-high 4-muon category.
Distribution of the four-lepton invariant mass in the four-lepton final state for the ggF-MVA-high 2e2mu category.
Distribution of the four-lepton invariant mass in the four-lepton final state for the ggF-MVA-high 4-electron category.
Electroweak symmetry breaking explains the origin of the masses of elementary particles through their interactions with the Higgs field. Besides the measurements of the Higgs boson properties, the study of the scattering of massive vector bosons with spin one allows the nature of electroweak symmetry breaking to be probed. Among all processes related to vector-boson scattering, the electroweak production of two jets and a $Z$-boson pair is a rare and important one. Here we report the observation of this process from proton-proton collision data corresponding to an integrated luminosity of 139/fb recorded at a centre-of-mass energy of 13 TeV with the ATLAS detector at the Large Hadron Collider. We consider two different final states originating from the decays of the $Z$-boson pair - one containing four charged leptons and the other containing two charged leptons and two neutrinos. The hypothesis of no electroweak production is rejected with a statistical significance of 5.7 $\sigma$, and the measured cross-section for electroweak production is consistent with the standard model prediction. In addition, we report cross-sections for inclusive production of a $Z$-boson pair and two jets for the two final states.
Signal strength and significance of EW ZZjj processes
Measured and predicted fiducial cross-sections in both the lllljj and ll$\nu\nu$jj channels for the inclusive ZZjj processes. Uncertainties due to different sources are presented.
Observed and expected multivariate discriminant distribution in the $\ell\ell\ell\ell jj$ QCD CR.
Combined ATLAS and CMS measurements of the Higgs boson production and decay rates, as well as constraints on its couplings to vector bosons and fermions, are presented. The combination is based on the analysis of five production processes, namely gluon fusion, vector boson fusion, and associated production with a $W$ or a $Z$ boson or a pair of top quarks, and of the six decay modes $H \to ZZ, WW$, $\gamma\gamma, \tau\tau, bb$, and $\mu\mu$. All results are reported assuming a value of 125.09 GeV for the Higgs boson mass, the result of the combined measurement by the ATLAS and CMS experiments. The analysis uses the CERN LHC proton--proton collision data recorded by the ATLAS and CMS experiments in 2011 and 2012, corresponding to integrated luminosities per experiment of approximately 5 fb$^{-1}$ at $\sqrt{s}=7$ TeV and 20 fb$^{-1}$ at $\sqrt{s} = 8$ TeV. The Higgs boson production and decay rates measured by the two experiments are combined within the context of three generic parameterisations: two based on cross sections and branching fractions, and one on ratios of coupling modifiers. Several interpretations of the measurements with more model-dependent parameterisations are also given. The combined signal yield relative to the Standard Model prediction is measured to be 1.09 $\pm$ 0.11. The combined measurements lead to observed significances for the vector boson fusion production process and for the $H \to \tau\tau$ decay of $5.4$ and $5.5$ standard deviations, respectively. The data are consistent with the Standard Model predictions for all parameterisations considered.
Best fit values of $\sigma_i \cdot \mathrm{B}^f$ for each specific channel $i \to H\to f$, as obtained from the generic parameterisation with 23 parameters for the combination of the ATLAS and CMS measurements, using the $\sqrt{s}$=7 and 8 TeV data. The cross sections are given for $\sqrt{s}$=8 TeV, assuming the SM values for $\sigma_i(7 \mathrm{TeV})/\sigma_i(8 \mathrm{TeV})$. The results are shown together with their total uncertainties and their breakdown into statistical and systematic components. The missing values are either not measured with a meaningful precision and therefore not quoted, in the case of the $H\to ZZ$ decay channel for the $WH$, $ZH$, and $ttH$ production processes, or not measured at all and therefore fixed to their corresponding SM predictions, in the case of the $H\to bb$ decay mode for the $gg\mathrm{F}$ and VBF production processes.
Best fit values of $\sigma_i \cdot \mathrm{B}^f$ relative to their SM prediction for each specific channel $i \to H\to f$, as obtained from the generic parameterisation with 23 parameters for the combination of the ATLAS and CMS measurements, using the $\sqrt{s}$=7 and 8 TeV data. The results are shown together with their total uncertainties and their breakdown into statistical and systematic components. The missing values are either not measured with a meaningful precision and therefore not quoted, in the case of the $H\to ZZ$ decay channel for the $WH$, $ZH$, and $ttH$ production processes, or not measured at all and therefore fixed to their corresponding SM predictions, in the case of the $H\to bb$ decay mode for the $gg\mathrm{F}$ and VBF production processes.
Best fit values of $\sigma(gg\to H\to ZZ)$, $\sigma_i/\sigma_{gg\mathrm{F}}$, and $\mathrm{B}^f/\mathrm{B}^{ZZ}$ from the combined analysis of the $\sqrt{s}$=7 and 8 TeV data. The values involving cross sections are given for $\sqrt{s}$=8 TeV, assuming the SM values for $\sigma_i(7 \mathrm{TeV})/\sigma_i(8 \mathrm{TeV})$. The results are shown for the combination of ATLAS and CMS, and also separately for each experiment, together with their total uncertainties and their breakdown into the four components described in the text. The expected uncertainties in the measurements are also shown.
Jet shapes have been measured in inclusive jet production in proton-proton collisions at sqrt(s) = 7 TeV using 3 pb^{-1} of data recorded by the ATLAS experiment at the LHC. Jets are reconstructed using the anti-kt algorithm with transverse momentum 30 GeV < pT < 600 GeV and rapidity in the region |y| < 2.8. The data are corrected for detector effects and compared to several leading-order QCD matrix elements plus parton shower Monte Carlo predictions, including different sets of parameters tuned to model fragmentation processes and underlying event contributions in the final state. The measured jets become narrower with increasing jet transverse momentum and the jet shapes present a moderate jet rapidity dependence. Within QCD, the data test a variety of perturbative and non-perturbative effects. In particular, the data show sensitivity to the details of the parton shower, fragmentation, and underlying event models in the Monte Carlo generators. For an appropriate choice of the parameters used in these models, the data are well described.
Measured Differential Jet Shape RHO as a function of r for jet transverse momentum from 30 to 40 GeV and absolute values of the jet rapidity from 0 to 2.8.
Measured Differential Jet Shape RHO as a function of r for jet transverse momentum from 40 to 60 GeV and absolute values of the jet rapidity from 0 to 2.8.
Measured Differential Jet Shape RHO as a function of r for jet transverse momentum from 60 to 80 GeV and absolute values of the jet rapidity from 0 to 2.8.
Measurements are presented from proton-proton collisions at centre-of-mass energies of sqrt(s) = 0.9, 2.36 and 7 TeV recorded with the ATLAS detector at the LHC. Events were collected using a single-arm minimum-bias trigger. The charged-particle multiplicity, its dependence on transverse momentum and pseudorapidity and the relationship between the mean transverse momentum and charged-particle multiplicity are measured. Measurements in different regions of phase-space are shown, providing diffraction-reduced measurements as well as more inclusive ones. The observed distributions are corrected to well-defined phase-space regions, using model-independent corrections. The results are compared to each other and to various Monte Carlo models, including a new AMBT1 PYTHIA 6 tune. In all the kinematic regions considered, the particle multiplicities are higher than predicted by the Monte Carlo models. The central charged-particle multiplicity per event and unit of pseudorapidity, for tracks with pT >100 MeV, is measured to be 3.483 +- 0.009 (stat) +- 0.106 (syst) at sqrt(s) = 0.9 TeV and 5.630 +- 0.003 (stat) +- 0.169 (syst) at sqrt(s) = 7 TeV.
Charged-particle multiplicities in proton-proton collisions at a centre-of mass energy of 900 GeV as a function of pseudorapidity for events with the number of charged particles >=1 having transverse momentum >500 MeV and absolute(pseudorapidity) <2.5.
Charged-particle multiplicities in proton-proton collisions at a centre-of mass energy of 2360 GeV as a function of pseudorapidity for events with the number of charged particles >=1 having transverse momentum >500 MeV and absolute(pseudorapidity) <2.5.
Charged-particle multiplicities in proton-proton collisions at a centre-of mass energy of 7000 GeV as a function of pseudorapidity for events with the number of charged particles >=1 having transverse momentum >500 MeV and absolute(pseudorapidity) <2.5.
A measurement of the cross section for the inclusive production of isolated prompt photons in pp collisions at a centre-of-mass energy sqrt(s) = 7TeV is presented. The measurement covers the pseudorapidity ranges |eta|<1.37 and 1.52<|eta|<1.81 in the transverse energy range 15 < E_T <100 GeV. The results are based on an integrated luminosity of 880 nb-1, collected with the ATLAS detector at the Large Hadron Collider. Photon candidates are identified by combining information from the calorimeters and from the inner tracker. Residual background in the selected sample is estimated from data based on the observed distribution of the transverse isolation energy in a narrow cone around the photon candidate. The results are compared to predictions from next-to-leading order perturbative QCD calculations.
The measured prompt photon cross section as a function of transverse energy for the |pseudorapidity| range < 0.6.
The measured prompt photon cross section as a function of transverse energy for the |pseudorapidity| range 0.6 to 1.37.
The measured prompt photon cross section as a function of transverse energy for the |pseudorapidity| range 1.52 to 1.81.