Measurement of Higgs boson decay into $b$-quarks in associated production with a top-quark pair in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Braden Keim ; Abbott, Dale ; et al.
CERN-EP-2021-202, 2021.
Inspire Record 1967501 DOI 10.17182/hepdata.114360

The associated production of a Higgs boson and a top-quark pair is measured in events characterised by the presence of one or two electrons or muons. The Higgs boson decay into a $b$-quark pair is used. The analysed data, corresponding to an integrated luminosity of 139 fb$^{-1}$, were collected in proton-proton collisions at the Large Hadron Collider between 2015 and 2018 at a centre-of-mass energy of $\sqrt{s}=13$ TeV. The measured signal strength, defined as the ratio of the measured signal yield to that predicted by the Standard Model, is $0.35^{+0.36}_{-0.34}$. This result is compatible with the Standard Model prediction and corresponds to an observed (expected) significance of 1.0 (2.7) standard deviations. The signal strength is also measured differentially in bins of the Higgs boson transverse momentum in the simplified template cross-section framework, including a bin for specially selected boosted Higgs bosons with transverse momentum above 300 GeV.

74 data tables

Comparison between data and prediction for the DNN $P(H)$ output for the Higgs boson candidate prior to any fit to the data in the single-lepton boosted channel for $300\le p_T^H<450$ GeV. The dashed line shows the ${t\bar {t}H}$ signal distribution normalised to the total background prediction. The uncertainty band includes all uncertainties and their correlations.

Comparison between data and prediction for the DNN $P(H)$ output for the Higgs boson candidate prior to any fit to the data in the single-lepton boosted channel for $p_{{T}}^{H}\ge 450$ GeV. The dashed line shows the ${t\bar {t}H}$ signal distribution normalised to the total background prediction. The uncertainty band includes all uncertainties and their correlations.

Performance of the Higgs boson reconstruction algorithms. For each row of `truth' ${\hat{p}_{{T}}^{H}}$, the matrix shows (in percentages) the fraction of all Higgs boson candidates with reconstructed $p_T^H$ in the various bins of the dilepton (left), single-lepton resolved (middle) and boosted (right) channels.

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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.
CERN-EP-2021-118, 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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Constraints on Higgs boson production with large transverse momentum using $H\rightarrow b\bar{b}$ decays in the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Braden Keim ; Abbott, Dale ; et al.
CERN-EP-2021-185, 2021.
Inspire Record 1969589 DOI 10.17182/hepdata.102183

This paper reports constraints on Higgs boson production with transverse momentum above 1 TeV. The analyzed data from proton-proton collisions at a center-of-mass energy of 13 TeV were recorded with the ATLAS detector at the Large Hadron Collider from 2015 to 2018 and correspond to an integrated luminosity of 136 fb$^{-1}$. Higgs bosons decaying into $b\bar{b}$ are reconstructed as single large-radius jets recoiling against a hadronic system and identified by the experimental signature of two $b$-hadron decays. The experimental techniques are validated in the same kinematic regime using the $Z\rightarrow b\bar{b}$ process. The 95% confidence-level upper limit on the cross section for Higgs boson production with transverse momentum above 450 GeV is 115 fb, and above 1 TeV it is 9.6 fb. The Standard Model predictions in the same kinematic regions are 18.4 fb and 0.13 fb, respectively.

11 data tables

- - - - - - - - Overview of HEPData Record - - - - - - - - <br/><br/> <b>Standard Model cross sections:</b> <a href="102183?table=SMcrosssections">table</a><br/><br/> <b>Cutflow ggF:</b> <a href="102183?table=CutflowggF">table</a><br/><br/> <b>Cutflow VBF:</b> <a href="102183?table=CutflowVBF">table</a><br/><br/> <b>Cutflow VH:</b> <a href="102183?table=CutflowVH">table</a><br/><br/> <b>Cutflow ttH:</b> <a href="102183?table=CutflowttH">table</a><br/><br/> <b>Production mode fractional contributions::</b> <a href="102183?table=Fractionalcontribution">table</a><br/><br/> <b>Acceptance times efficiency - fiducial:</b> <a href="102183?table=Acceptancetimesefficiency-fiducial">table</a><br/><br/> <b>Acceptance times efficiency - differential:</b> <a href="102183?table=Acceptancetimesefficiency-differential">table</a><br/><br/> <b>Yield table - fiducial:</b> <a href="102183?table=Eventyields-fiducial">table</a><br/><br/> <b>Yield table - differential:</b> <a href="102183?table=Eventyields-differential">table</a><br/><br/>

Predicted Higgs boson production cross sections within fiducial volumes obtained from the four production mode MC samples (ggF, VBF, VH, and ttH) described in Section 3 with and without higher order electroweak (EW) corrections. All μH values reported are with respect to cross section with EW corrections.

The efficiency for simulated ggF events to pass each analysis cut.

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Search for associated production of a $Z$ boson with an invisibly decaying Higgs boson or dark matter candidates at $\sqrt{s}=13$ TeV with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Braden Keim ; Abbott, Dale ; et al.
CERN-EP-2021-204, 2021.
Inspire Record 1969392 DOI 10.17182/hepdata.114363

A search for invisible decays of the Higgs boson as well as searches for dark matter candidates, produced together with a leptonically decaying $Z$ boson, are presented. The analysis is performed using proton-proton collisions at a centre-of-mass energy of 13 TeV, delivered by the LHC, corresponding to an integrated luminosity of 139 fb$^{-1}$ and recorded by the ATLAS experiment. Assuming Standard Model cross-sections for $ZH$ production, the upper limit on the branching ratio of the Higgs boson to invisible particles is found to be 19% at the 95% confidence level. Exclusion limits are also set for simplified dark matter models and 2HDM$+a$ models.

28 data tables

The expected exclusion contours as a function of (m(med), m($\chi$)), with Axial-vector mediator)

The observed exclusion contours as a function of (m(med), m($\chi$)), with Axial-vector mediator)

The expected exclusion contours as a function of (m(med), m($\chi$)), with Vector mediator)

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Study of the doubly charmed tetraquark $T_{cc}^+$

The LHCb collaboration Aaij, Roel ; Abdelmotteleb, Ahmed Sameh Wagih ; Abellán Beteta, Carlos ; et al.
CERN-EP-2021-169, 2021.
Inspire Record 1915358 DOI 10.17182/hepdata.113470

An exotic narrow state in the $D^0D^0\pi^+$ mass spectrum just below the $D^{*+}D^0$ mass threshold is studied using a data set corresponding to an integrated luminosity of 9 fb$^{-1}$ acquired with the LHCb detector in proton-proton collisions at centre-of-mass energies of 7, 8 and 13 TeV. The state is consistent with the ground isoscalar $T^+_{cc}$ tetraquark with a quark content of $cc\bar{u}\bar{d}$ and spin-parity quantum numbers $\mathrm{J}^{\mathrm{P}}=1^+$. Study of the $DD$ mass spectra disfavours interpretation of the resonance as the isovector state. The decay structure via intermediate off-shell $D^{*+}$ mesons is confirmed by the $D^0\pi^+$ mass distribution. The mass of the resonance and its coupling to the $D^{*}D$ system are analysed. Resonance parameters including the pole position, scattering length, effective range and compositeness are measured to reveal important information about the nature of the $T^+_{cc}$ state. In addition, an unexpected dependence of the production rate on track multiplicity is observed.

20 data tables

Distribution of $D^0 D^0 \pi^+$ mass where the contribution of the non-$D^0$ background has been statistically subtracted. Uncertainties on the data points are statistical only and represent one standard deviation, calculated as a sum in quadrature of the assigned weights from the background-subtraction procedure.

Mass distribution for $D^0 \pi^+$ pairs from selected $D^0 D^0 \pi^+$ candidates with a mass below the $D^{*+}D^0$ mass threshold with non-$D^0$ background subtracted. Uncertainties on the data points are statistical only and represent one standard deviation, calculated as a sum in quadrature of the assigned weights from the background-subtraction procedure.

$D^0 D^0$~mass distributions for selected candidates with the $D^0$ background subtracted. Uncertainties on the data points are statistical only and represent one standard deviation, calculated as a sum in quadrature of the assigned weights from the background-subtraction procedure.

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Observation of an exotic narrow doubly charmed tetraquark

The LHCb collaboration Aaij, Roel ; Abdelmotteleb, Ahmed Sameh Wagih ; Abellán Beteta, Carlos ; et al.
CERN-EP-2021-165, 2021.
Inspire Record 1915457 DOI 10.17182/hepdata.114869

Conventional hadronic matter consists of baryons and mesons made of three quarks and quark-antiquark pairs, respectively. The observation of a new type of hadronic state, a doubly charmed tetraquark containing two charm quarks, an anti-$u$ and an anti-$d$ quark, is reported using data collected by the LHCb experiment at the Large Hadron Collider. This exotic state with a mass of about 3875 MeV$/c^2$ manifests itself as a narrow peak in the mass spectrum of $D^0D^0\pi^+$ mesons just below the $D^{*+}D^0$ mass threshold. The near threshold mass together with a strikingly narrow width reveals the resonance nature of the state.

2 data tables

Distribution of $D^0 D^0 \pi^+$ mass where the contribution of the non-$D^0$ background has been statistically subtracted. Uncertainties on the data points are statistical only and represent one standard deviation, calculated as a sum in quadrature of the assigned weights from the background-subtraction procedure.

Distribution of $D^0 D^0 \pi^+$ mass where the contribution of the non-$D^0$ background has been statistically subtracted by assigning the a weight to every candidate.


Search for Higgs bosons decaying into new spin-0 or spin-1 particles in four-lepton final states with the ATLAS detector with 139 fb$^{-1}$ of $pp$ collision data at $\sqrt{s}=13$ TeV

The ATLAS collaboration Aad, Georges ; Abbott, Braden Keim ; Abbott, Dale ; et al.
CERN-EP-2021-193, 2021.
Inspire Record 1954278 DOI 10.17182/hepdata.111057

Searches are conducted for new spin-0 or spin-1 bosons using events where a Higgs boson with mass $125$ GeV decays into four leptons ($\ell =$$e$,$\mu$). This decay is presumed to occur via an intermediate state which contains two on-shell, promptly decaying bosons: $H \rightarrow XX/ZX \rightarrow 4\ell$, where the new boson $X$ has a mass between 1 and 60 GeV. The search uses $pp$ collision data collected with the ATLAS detector at the LHC with an integrated luminosity of 139 fb$^{-1}$ at a centre-of-mass energy $\sqrt{s}=13$ TeV. The data are found to be consistent with Standard Model expectations. Limits are set on fiducial cross sections and on the branching ratio of the Higgs boson to decay into $XX/ZX$, improving those from previous publications by a factor between two and four. Limits are also set on mixing parameters relevant in extensions of the Standard Model containing a dark sector where $X$ is interpreted to be a dark boson.

31 data tables

Distribution of $\langle m_{\ell\ell}\rangle$ for events selected in the HM $H\to XX \to 4\ell$ $\, ( 15 \,\text{GeV} < m_{X} < 60 \,\text{GeV})$ analysis. (Pre-fit background expectations and signal templates for $m_{Z_d} = 20 \,\text{GeV}$, $35 \,\text{GeV}$, and $55 \,\text{GeV}$ are given. The latter's yields are normalized with $\sigma(pp\to H\to Z_dZ_d\to 4\ell) =\frac{1}{10}\sigma_{\textrm{SM}}(pp\to H\to ZZ^*\to 4\ell)$.

Distribution of $\langle m_{\ell\ell}\rangle$ for events selected in the LM $H\to XX \to 4\mu$ $( 1 \,\text{GeV} < m_{X} < 15 \, \text{GeV} )$ analysis. The regions of 2 GeV to 4.4 GeV, and 8 GeV to 12 GeV are each excluded by the quarkonia veto. No data events pass this selection. Background expectations are pre-fit. Signal templates for $m_{Z_d} = 2 \,\text{GeV}$, $6 \,\text{GeV}$, and $15 \,\text{GeV}$ are given. All signal yields are normalized with $\sigma(pp\to H\to aa\to 4\mu) = \frac{1}{10}\sigma_{\textrm{SM}}(pp\to H\to ZZ^*\to 4\mu) = 0.15 \text{ fb}$ .

Distribution of $m_{34}$ for data and background events in the mass range $115 \,\text{GeV} < m_{4\ell} < 130 \,\text{GeV}$ after the $H\to ZX\to 4\ell$ selection. The background yield for the $H \to ZZ^* \to 4\ell$ process is post-fit and constrained to $1.2 \pm 0.16$ times the Standard Model expectation. Three $H \to ZZ_d \to 4\ell$ signal templates are shown for $Z_d$ masses of $m_{Z_d} = 20 \,\text{GeV}$, $35 \,\text{GeV}$, and $55 \,\text{GeV}$. They are normalized to a branching ratio of $\textrm{BR}(H\rightarrow ZZ_d \rightarrow 4\ell) = \frac{1}{10}\textrm{BR}(H\rightarrow ZZ^*\rightarrow 4\ell)$.

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Search for charged-lepton-flavour violation in $Z$-boson decays with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abbott, Dale Charles ; et al.
Nature Phys. 17 (2021) 819 819-825, 2021.
Inspire Record 1821688 DOI 10.17182/hepdata.96390

The ATLAS experiment at the Large Hadron Collider reports a search for charged-lepton-flavour violation in decays of $Z$ bosons into a τ lepton and an electron or muon of opposite charge.

9 data tables

The best-fit expected and observed distributions of the combined NN output in the CRZ$\tau\tau$ for the $\mu\tau$ channel for events with 1-prong $\tau_\text{had-vis}$ candidates. The last bin in each plot includes overflow events.

The best-fit expected and observed distributions of the combined NN output in the CRZ$\tau\tau$ for the $\mu\tau$ channel for events with 3-prong $\tau_\text{had-vis}$ candidates. The last bin in each plot includes overflow events.

The best-fit expected and observed distributions of the combined NN output in the VRSS for the $e\tau$ channel for events with 1-prong $\tau_\text{had-vis}$ candidates. The last bin in each plot includes overflow events.

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Version 3
Measurement of the transverse momentum distribution of Drell–Yan lepton pairs in proton–proton collisions at $\sqrt{s}=13$ TeV with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abbott, Dale Charles ; et al.
Eur.Phys.J.C 80 (2020) 616, 2020.
Inspire Record 1768911 DOI 10.17182/hepdata.92377

This paper describes precision measurements of the transverse momentum $p_\mathrm{T}^{\ell\ell}$ ($\ell=e,\mu$) and of the angular variable $\phi^{*}_{\eta}$ distributions of Drell-Yan lepton pairs in a mass range of 66-116 GeV. The analysis uses data from 36.1 fb$^{-1}$ of proton-proton collisions at a centre-of-mass energy of $\sqrt{s}=13$ TeV collected by the ATLAS experiment at the LHC in 2015 and 2016. Measurements in electron-pair and muon-pair final states are performed in the same fiducial volumes, corrected for detector effects, and combined. Compared to previous measurements in proton-proton collisions at $\sqrt{s}=$7 and 8 TeV, these new measurements probe perturbative QCD at a higher centre-of-mass energy with a different composition of initial states. They reach a precision of 0.2% for the normalized spectra at low values of $p_\mathrm{T}^{\ell\ell}$. The data are compared with different QCD predictions, where it is found that predictions based on resummation approaches can describe the full spectrum within uncertainties.

28 data tables

Selected signal candidate events in data for both decay channels as well as the expected background contributions including their total uncertainties.

Overview of the detector efficiency correction factors, $C_{Z}$ , for the electron and muon channels and their systematic uncertainty contributions.

Measured inclusive cross-section in the fiducial volume in the electron and muon decay channels at Born level and their combination as well as the theory prediction at NNLO in $\alpha_{s}$ using the CT14 PDF set.

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Version 2
Search for resonances decaying into photon pairs in 139 fb−1 of pp collisions at s=13 TeV with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abbott, Dale Charles ; et al.
Phys.Lett.B 822 (2021) 136651, 2021.
Inspire Record 1849059 DOI 10.17182/hepdata.100161

Searches for new resonances in the diphoton final state, with spin 0 as predicted by theories with an extended Higgs sector and with spin 2 using a warped extra-dimension benchmark model, are presented using 139 fb$^{-1}$ of $\sqrt{s} = $ 13 TeV $pp$ collision data collected by the ATLAS experiment at the LHC. No significant deviation from the Standard Model is observed and upper limits are placed on the production cross-section times branching ratio to two photons as a function of the resonance mass.

16 data tables

The expected and observed upper limits at 95\% CL on the fiducial cross-section times branching ratio to two photons of a narrow-width (Γ_X = 4 MeV) spin-0 resonance as a function of its mass m_X. For masses greater than 1000 GeV, pseudo-experiments are used to verify the expected and observed limits, and used in place of the asymptotic limit when differences are observed.

The expected and observed upper limits at 95\% CL on the production cross-section times branching ratio to two photons of the lightest KK graviton as a function of its mass for k/Mpl=0.10. For masses greater than 1000 GeV, pseudo-experiments are used to verify the expected and observed limits, and used in place of the asymptotic limit when differences are observed.

Expected and observed limits computed using asymptotic formulas as a function of the signal mass m_{X} and the relative width $\Gamma_{X}/m_{X}$ for the spin-0 resonance search.

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