Date

Measurement of photon-jet transverse momentum correlations in 5.02 TeV Pb+Pb and $pp$ collisions with ATLAS

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
Phys.Lett.B 789 (2019) 167-190, 2019.
Inspire Record 1694678 DOI 10.17182/hepdata.85369

Jets created in association with a photon can be used as a calibrated probe to study energy loss in the medium created in nuclear collisions. Measurements of the transverse momentum balance between isolated photons and inclusive jets are presented using integrated luminosities of 0.49 nb$^{-1}$ of Pb+Pb collision data at $\sqrt{s_\mathrm{NN}}=5.02$ TeV and 25 pb$^{-1}$ of $pp$ collision data at $\sqrt{s}=5.02$ TeV recorded with the ATLAS detector at the LHC. Photons with transverse momentum $63.1 < p_\mathrm{T}^{\gamma} < 200$ GeV and $\left|\eta^{\gamma}\right| < 2.37$ are paired inclusively with all jets in the event that have $p_\mathrm{T}^\mathrm{jet} > 31.6$ GeV and pseudorapidity $\left|\eta^\mathrm{jet}\right| < 2.8$. The transverse momentum balance given by the jet-to-photon $p_\mathrm{T}$ ratio, $x_\mathrm{J\gamma}$, is measured for pairs with azimuthal opening angle $\Delta\phi > 7\pi/8$. Distributions of the per-photon jet yield as a function of $x_\mathrm{J\gamma}$, $(1/N_\gamma)(\mathrm{d}N/\mathrm{d}x_\mathrm{J\gamma})$, are corrected for detector effects via a two-dimensional unfolding procedure and reported at the particle level. In $pp$ collisions, the distributions are well described by Monte Carlo event generators. In Pb+Pb collisions, the $x_\mathrm{J\gamma}$ distribution is modified from that observed in $pp$ collisions with increasing centrality, consistent with the picture of parton energy loss in the hot nuclear medium. The data are compared with a suite of energy-loss models and calculations.

6 data tables

Photon-jet pT balance distributions (1/Ng)(dN/dxJg) in pp events (blue, reproduced on all panels) and Pb+Pb events (red) with each panel denoting a different centrality selection. These panels show results with pTg = 63.1-79.6 GeV. Total systematic uncertainties are shown as boxes, while statistical uncertainties are shown with vertical bars.

Photon-jet pT balance distributions (1/Ng)(dN/dxJg) in pp events (blue, reproduced on all panels) and Pb+Pb events (red) with each panel denoting a different centrality selection. These panels show results with pTg = 79.6-100 GeV. Total systematic uncertainties are shown as boxes, while statistical uncertainties are shown with vertical bars.

Photon-jet pT balance distributions (1/Ng)(dN/dxJg) in pp events (blue, reproduced on all panels) and Pb+Pb events (red) with each panel denoting a different centrality selection. These panels show results with pTg = 100-158 GeV. Total systematic uncertainties are shown as boxes, while statistical uncertainties are shown with vertical bars.

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Search for leptoquarks coupled to third-generation quarks in proton-proton collisions at $\sqrt{s} =$ 13 TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Phys.Rev.Lett. 121 (2018) 241802, 2018.
Inspire Record 1694381 DOI 10.17182/hepdata.85765

Three of the most significant measured deviations from standard model predictions, the enhanced decay rate for B $\to$ D$^{(*)}\tau\nu$, hints of lepton universality violation in B $\to$ K$^{(*)}\ell\ell$ decays, and the anomalous magnetic moment of the muon, can be explained by the existence of leptoquarks (LQs) with large couplings to third-generation quarks and masses at the TeV scale. The existence of these states can be probed at the LHC in high energy proton-proton collisions. A novel search is presented for pair production of LQs coupled to a top quark and a muon using data at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{-1}$, recorded by the CMS experiment. No deviation from the standard model prediction has been observed and scalar LQs decaying exclusively into t$\mu$ are excluded up to masses of 1420 GeV. The results of this search are combined with those from previous searches for LQ decays into t$\tau$ and b$\nu$, which excluded scalar LQs below masses of 900 and 1080 GeV. Vector LQs are excluded up to masses of 1190 GeV for all possible combinations of branching fractions to t$\mu$, t$\tau$ and b$\nu$. With this analysis, all relevant couplings of LQs with an electric charge of -1/3 to third-generation quarks are probed for the first time.

6 data tables

Distributions for $M_{LQ}^{rec}$ (category A) after applying the full selection. All backgrounds are normalized according to the post-fit nuisance parameters based on the corresponding SM cross sections.

Distributions for $S_{T}$ (category B) after applying the full selection and estimating the $t\overline{t}$ and DY+jets background contributions from data in category B. All backgrounds are normalized according to the post-fit nuisance parameters based on the corresponding SM cross sections.

Observed upper limits on the production cross section for pair production of LQs decaying into a top quark and a muon or a $\tau$ lepton at 95% CL in the $M_{LQ} - B(LQ \rightarrow t\mu)$ plane.

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Studies of B$^*_\mathrm{s2}(5840)^0$ and B$_\mathrm{s1}(5830)^0$ mesons including the observation of the B$^*_\mathrm{s2}(5840)^0\to$ B$^0$K$_\mathrm{S}^0$ decay in proton-proton collisions at $\sqrt{s}=$8 TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Eur.Phys.J.C 78 (2018) 939, 2018.
Inspire Record 1693614 DOI 10.17182/hepdata.85740

Measurements of $\mathrm{B}^*_\mathrm{s2}(5840)^0$ and $\mathrm{B}_\mathrm{s1}(5830)^0$ mesons are performed using a data sample of proton-proton collisions corresponding to an integrated luminosity of 19.6 fb$^{-1}$, collected with the CMS detector at the LHC at a centre-of-mass energy of 8 TeV. The analysis studies $P$-wave $\mathrm{B}^0_\mathrm{S}$ meson decays into $\mathrm{B}^{(*)+}\mathrm{K}^-$ and $\mathrm{B}^{(*)0}\mathrm{K}^0_\mathrm{S}$, where the $\mathrm{B}^+$ and $\mathrm{B}^0$ mesons are identified using the decays $\mathrm{B}^+\to\mathrm{J}/\psi\,\mathrm{K}^+$ and $\mathrm{B}^0\to\mathrm{J}/\psi\,\mathrm{K}^*(892)^0$. The masses of the $P$-wave $\mathrm{B}^0_\mathrm{S}$ meson states are measured and the natural width of the $\mathrm{B}^*_\mathrm{s2}(5840)^0$ state is determined. The first measurement of the mass difference between the charged and neutral $\mathrm{B}^*$ mesons is also presented. The $\mathrm{B}^*_\mathrm{s2}(5840)^0$ decay to $\mathrm{B}^0\mathrm{K}^0_\mathrm{S}$ is observed, together with a measurement of its branching fraction relative to the $\mathrm{B}^*_\mathrm{s2}(5840)^0\to\mathrm{B}^+\mathrm{K}^-$ decay.

12 data tables

The $\mathrm{J}/\psi\mathrm{K}^+$ invariant mass distribution in data

The $\mathrm{J}/\psi\mathrm{K}^{*0}$ invariant mass distribution in data

The $\mathrm{B}^+\pi^-$ invariant mass distribution of the selected candidates in data

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Search for pairs of highly collimated photon-jets in $pp$ collisions at $\sqrt{s}$ = 13 TeV with the ATLAS detector

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
Phys.Rev.D 99 (2019) 012008, 2019.
Inspire Record 1692387 DOI 10.17182/hepdata.85728

Results of a search for the pair production of photon-jets$-$collimated groupings of photons$-$in the ATLAS detector at the Large Hadron Collider are reported. Highly collimated photon-jets can arise from the decay of new, highly boosted particles that can decay to multiple photons collimated enough to be identified in the electromagnetic calorimeter as a single, photonlike energy cluster. Data from proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 36.7 fb$^{-1}$, were collected in 2015 and 2016. Candidate photon-jet pair production events are selected from those containing two reconstructed photons using a set of identification criteria much less stringent than that typically used for the selection of photons, with additional criteria applied to provide improved sensitivity to photon-jets. Narrow excesses in the reconstructed diphoton mass spectra are searched for. The observed mass spectra are consistent with the Standard Model background expectation. The results are interpreted in the context of a model containing a new, high-mass scalar particle with narrow width, $X$, that decays into pairs of photon-jets via new, light particles, $a$. Upper limits are placed on the cross section times the product of branching ratios $\sigma \times \mathcal{B}(X \rightarrow aa) \times \mathcal {B}(a \rightarrow \gamma \gamma)^{2}$ for 200 GeV $< m_{X} <$ 2 TeV and for ranges of $ m_a $ from a lower mass of 100 MeV up to between 2 and 10 GeV, depending upon $ m_X $. Upper limits are also placed on $\sigma \times \mathcal{B}(X \rightarrow aa) \times \mathcal {B}(a \rightarrow 3\pi^{0})^{2}$ for the same range of $ m_X $ and for ranges of $ m_a $ from a lower mass of 500 MeV up to between 2 and 10 GeV.

35 data tables

Distribution of the reconstructed diphoton mass for data events passing the analysis selection, in the low-$\Delta E$ category. There are no data events above 2700 GeV.

Distribution of the reconstructed diphoton mass for data events passing the analysis selection, in the high-$\Delta E$ category. There are no data events above 2700 GeV.

The observed upper limits on the production cross-section times the product of branching ratios for the benchmark signal scenario involving a scalar particle $X$ with narrow width decaying via $X\rightarrow aa\rightarrow 4\gamma$, $\sigma_X\times B(X\rightarrow aa)\times B(a\rightarrow\gamma\gamma)^2$. The limits for $m_{a}$ = 5 GeV and 10 GeV do not cover as large a range as the other mass points, since the region of interest is limited to $ m_{a} < 0.01 \times m_{X}$.

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Version 2
Measurement of jet substructure observables in $\mathrm{t\overline{t}}$ events from proton-proton collisions at $\sqrt{s} =$ 13TeV

The CMS collaboration Sirunyan, A. M. ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Phys.Rev.D 98 (2018) 092014, 2018.
Inspire Record 1690148 DOI 10.17182/hepdata.84716

A measurement of jet substructure observables is presented using \ttbar events in the lepton+jets channel from proton-proton collisions at $\sqrt{s}=$ 13 TeV recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. Multiple jet substructure observables are measured for jets identified as bottom, light-quark, and gluon jets, as well as for inclusive jets (no flavor information). The results are unfolded to the particle level and compared to next-to-leading-order predictions from POWHEG interfaced with the parton shower generators PYTHIA 8 and HERWIG 7, as well as from SHERPA 2 and DIRE2. A value of the strong coupling at the Z boson mass, $\alpha_S(m_\mathrm{Z}) = $ 0.115$^{+0.015}_{-0.013}$, is extracted from the substructure data at leading-order plus leading-log accuracy.

132 data tables

Distribution of $\lambda_{0}^{0}$ (N) reconstructed from charged particles with pt > 1 GeV, unfolded to the particle level.

Distribution of $\lambda_{0}^{2}$ ($p_{T}^{d,*})$ reconstructed from charged particles with pt > 1 GeV, unfolded to the particle level.

Distribution of $\lambda_{0.5}^{1}$ (LHA) reconstructed from charged particles with pt > 1 GeV, unfolded to the particle level.

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Search for a charged Higgs boson decaying to charm and bottom quarks in proton-proton collisions at $\sqrt{s} =$ 8 TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
JHEP 11 (2018) 115, 2018.
Inspire Record 1688938 DOI 10.17182/hepdata.87251

A search for charged Higgs boson decaying to a charm and a bottom quark (H$^+\to$ c$\overline{\mathrm{b}}$) is performed using 19.7 fb$^{-1}$ of pp collision data at $\sqrt{s} =$ 8 TeV. The production mechanism investigated in this search is $\mathrm{t\overline{t}}$ pair production in which one top quark decays to a charged Higgs boson and a bottom quark and the other decays to a charged lepton, a neutrino, and a bottom quark. Charged Higgs boson decays to $\mathrm{c\overline{b}}$ are searched for, resulting in a final state containing at least four jets, a charged lepton (muon or electron), and missing transverse momentum. A kinematic fit is performed to identify the pair of jets least likely to be the bottom quarks originating from direct top quark decays and the invariant mass of this pair is used as the final observable in the search. No evidence for the presence of a charged Higgs boson is observed and upper limits at 95% confidence level of 0.8-0.5% are set on the branching fraction $\mathcal{B}$(t $\to$ H$^+$b), assuming $\mathcal{B}$(H$^+\to$ $\mathrm{c\overline{b}}) =$ 1.0 and $\mathcal{B}$(t $\to$ H$^+$b) $+$ $\mathcal{B}$(t $\to$ Wb) = 1.0, for the charged Higgs boson mass range 90-150 GeV.

1 data table

The 95% CL upper limits on the branching fraction of top quark to a charged Higgs boson and bottom quark depending on the expected charged Higgs mass. For this limit calculation, B(t --> H+ b) + B(t --> W b) = 1.0 and B(H+ --> cb) = 1.0 are assumed.


Version 2
Search for squarks and gluinos in final states with hadronically decaying $\tau$-leptons, jets, and missing transverse momentum using $pp$ collisions at $\sqrt{s}$ = 13 TeV with the ATLAS detector

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
Phys.Rev.D 99 (2019) 012009, 2019.
Inspire Record 1688943 DOI 10.17182/hepdata.84426

A search for supersymmetry in events with large missing transverse momentum, jets, and at least one hadronically decaying $\tau$-lepton is presented. Two exclusive final states with either exactly one or at least two $\tau$-leptons are considered. The analysis is based on proton-proton collisions at $\sqrt{s}$ = 13 TeV corresponding to an integrated luminosity of 36.1 fb$^{-1}$ delivered by the Large Hadron Collider and recorded by the ATLAS detector in 2015 and 2016. No significant excess is observed over the Standard Model expectation. At 95% confidence level, model-independent upper limits on the cross section are set and exclusion limits are provided for two signal scenarios: a simplified model of gluino pair production with $\tau$-rich cascade decays, and a model with gauge-mediated supersymmetry breaking (GMSB). In the simplified model, gluino masses up to 2000 GeV are excluded for low values of the mass of the lightest supersymmetric particle (LSP), while LSP masses up to 1000 GeV are excluded for gluino masses around 1400 GeV. In the GMSB model, values of the supersymmetry-breaking scale are excluded below 110 TeV for all values of $\tan\beta$ in the range $2 \leq \tan\beta \leq 60$, and below 120 TeV for $\tan\beta>30$.

52 data tables

1$\tau$ Compressed SR eff.

1$\tau$ MediumMass SR eff.

2$\tau$ Compressed SR eff.

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Search for heavy charged long-lived particles in proton-proton collisions at $\sqrt{s} = 13$ TeV using an ionisation measurement with the ATLAS detector

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
Phys.Lett.B 788 (2019) 96-116, 2019.
Inspire Record 1686832 DOI 10.17182/hepdata.83962

This Letter presents a search for heavy charged long-lived particles produced in proton-proton collisions at $\sqrt{s} = 13$ TeV at the LHC using a data sample corresponding to an integrated luminosity of 36.1 fb$^{-1}$ collected by the ATLAS experiment in 2015 and 2016. These particles are expected to travel with a velocity significantly below the speed of light, and therefore have a specific ionisation higher than any high-momentum Standard Model particle of unit charge. The pixel subsystem of the ATLAS detector is used in this search to measure the ionisation energy loss of all reconstructed charged particles which traverse the pixel detector. Results are interpreted assuming the pair production of $R$-hadrons as composite colourless states of a long-lived gluino and Standard Model partons. No significant deviation from Standard Model background expectations is observed, and lifetime-dependent upper limits on $R$-hadron production cross-sections and gluino masses are set, assuming the gluino always decays in two quarks and a stable neutralino. $R$-hadrons with lifetimes above 1.0 ns are excluded at the 95% confidence level, with lower limits on the gluino mass ranging between 1290 GeV and 2060 GeV. In the case of stable $R$-hadrons, the lower limit on the gluino mass at the 95% confidence level is 1890 GeV.

26 data tables

The number of events in each CR, VR, and SR for the predicted background, for the expected contribution from the signal model normalised to $36.1$ fb$^{-1}$, and in the observed data. The predicted background includes the statistical and systematic uncertainties, respectively. The uncertainty in the signal yield includes all systematic uncertainties except that in the theoretical cross-section.

The number of events in each CR, VR, and SR for the predicted background, for the expected contribution from the signal model normalised to $36.1$ fb$^{-1}$, and in the observed data. The predicted background includes the statistical and systematic uncertainties, respectively. The uncertainty in the signal yield includes all systematic uncertainties except that in the theoretical cross-section.

Expected number of $R$-hadron signal events at different stages of the selection, normalised to $36.1$ fb$^{-1}$. Shown for three different signal points is the number of events expected and the number of events expected in which the selected track has been matched to a generated $R$-hadron. If the gluino decays, it decays to a 100 GeV $\tilde{\chi}^{0}$ and SM quarks.

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Measurement of the azimuthal anisotropy of charged particles produced in $\sqrt{s_\mathrm{NN}} = 5.02$ TeV Pb+Pb collisions with the ATLAS detector

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
Eur.Phys.J.C 78 (2018) 997, 2018.
Inspire Record 1686834 DOI 10.17182/hepdata.84427

Measurements of the azimuthal anisotropy in lead-lead collisions at $\sqrt{s_\mathrm{NN}} = 5.02$ TeV are presented using a data sample corresponding to 0.49 $\mathrm{nb}^{-1}$ integrated luminosity collected by the ATLAS experiment at the LHC in 2015. The recorded minimum-bias sample is enhanced by triggers for "ultra-central" collisions, providing an opportunity to perform detailed study of flow harmonics in the regime where the initial state is dominated by fluctuations. The anisotropy of the charged-particle azimuthal angle distributions is characterized by the Fourier coefficients, $v_{2}-v_{7}$, which are measured using the two-particle correlation, scalar-product and event-plane methods. The goal of the paper is to provide measurements of the differential as well as integrated flow harmonics $v_{n}$ over wide ranges of the transverse momentum, 0.5 $

456 data tables

The V2 harmonic measured with the scalar product method as a funtion of transverse momentum in centrality bin 0-0.1%

The V2 harmonic measured with the scalar product method as a funtion of transverse momentum in centrality bin 0-1%

The V2 harmonic measured with the scalar product method as a funtion of transverse momentum in centrality bin 0-5%

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Search for charged Higgs bosons decaying into top and bottom quarks at $\sqrt{s}$ = 13 TeV with the ATLAS detector

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
JHEP 11 (2018) 085, 2018.
Inspire Record 1686365 DOI 10.17182/hepdata.83203

A search for charged Higgs bosons heavier than the top quark and decaying via $H^\pm \rightarrow tb$ is presented. The data analysed corresponds to 36.1 fb$^{-1}$ of $pp$ collisions at $\sqrt{s}$ = 13 TeV and was recorded with the ATLAS detector at the LHC in 2015 and 2016. The production of a charged Higgs boson in association with a top quark and a bottom quark, $pp \rightarrow tb H^\pm$, is explored in the mass range from $m_{H^\pm}$ = 200 to 2000 GeV using multi-jet final states with one or two electrons or muons. Events are categorised according to the multiplicity of jets and how likely these are to have originated from hadronisation of a bottom quark. Multivariate techniques are used to discriminate between signal and background events. No significant excess above the background-only hypothesis is observed and exclusion limits are derived for the production cross-section times branching fraction of a charged Higgs boson as a function of its mass, which range from 2.9 pb at $m_{H^\pm}$ = 200 GeV to 0.070 pb at $m_{H^\pm}$ = 2000 GeV. The results are interpreted in two benchmark scenarios of the Minimal Supersymmetric Standard Model.

5 data tables

Expected and observed limits for the production of $H^{+} \to tb$ in association with a top quark and a bottom quark. The bands surrounding the expected limit show the 68% and 95% confidence intervals. The limits are based on the combination of the $\ell+$jets and $\ell\ell$ final states. Theory predictions are shown for three representative values of $\tan\beta$ in the $m_h^{\mathrm{mod-}}$ benchmark scenario. Uncertainties in the predicted $H^+$ cross-sections or branching ratios are not considered.

Expected and observed upper limits on $\tan\beta$ as a function of $m_{H^{+}}$ in the $m_h^{\mathrm{mod-}}$ scenario of the MSSM. Limits are shown for $\tan\beta$ values in the range of 0.5-60, where predictions are available from both scenarios. The bands surrounding the expected limits show the 68% and 95% confidence intervals. The limits are based on the combination of the $\ell+$jets and $\ell\ell$ final states. The production cross-section of $t\bar{t}H$ and $tH$, as well as the branching ratios of the $H$, are fixed to their SM values at each point in the plane. Uncertainties on the predicted $H^{+}$ cross-sections or branching ratios are not considered.

Expected and observed lower limits on $\tan\beta$ as a function of $m_{H^{+}}$ in the $m_h^{\mathrm{mod-}}$ scenario of the MSSM. Limits are shown for $\tan\beta$ values in the range of 0.5-60, where predictions are available from both scenarios. The bands surrounding the expected limits show the 68% and 95% confidence intervals. The limits are based on the combination of the $\ell+$jets and $\ell\ell$ final states. The production cross-section of $t\bar{t}H$ and $tH$, as well as the branching ratios of the $H$, are fixed to their SM values at each point in the plane. Uncertainties on the predicted $H^{+}$ cross-sections or branching ratios are not considered.

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