Observation of single-top-quark production in association with a photon using the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Braden Keim ; Abbott, D.C. ; et al.
Phys.Rev.Lett. 131 (2023) 181901, 2023.
Inspire Record 2628980 DOI 10.17182/hepdata.134244

This Letter reports the observation of single top quarks produced together with a photon, which directly probes the electroweak coupling of the top quark. The analysis uses 139 fb$^{-1}$ of 13 TeV proton-proton collision data collected with the ATLAS detector at the Large Hadron Collider. Requiring a photon with transverse momentum larger than 20 GeV and within the detector acceptance, the fiducial cross section is measured to be 688 $\pm$ 23 (stat.) $^{+75}_{-71}$ (syst.) fb, to be compared with the standard model prediction of 515 $^{+36}_{-42}$ fb at next-to-leading order in QCD.

26 data tables

This table shows the values for $\sigma_{tq\gamma}\times\mathcal{B}(t\rightarrow l\nu b)$ and $\sigma_{tq\gamma}\times\mathcal{B}(t\rightarrow l\nu b)+\sigma_{t(\rightarrow l\nu b\gamma)q}$ obtained by a profile-likelihood fit in the fiducial parton-level phase space (defined in Table 1) and particle-level phase space (defined in Table 2), respectively.

Distribution of the reconstructed top-quark mass in the $W\gamma\,$CR before the profile-likelihood fit. The "Total" column corresponds to the sum of the expected contributions from the signal and background processes. The uncertainty represents the sum of statistical and systematic uncertainties in the signal and background predictions. The first and last bins include the underflow and overflow, respectively.

Distribution of the NN output in the 0fj$\,$SR in data and the expected contribution of the signal and background processes after the profile-likelihood fit. The "Total" column corresponds to the sum of the expected contributions from the signal and background processes. The uncertainty represents the sum of statistical and systematic uncertainties in the signal and background predictions considering the correlations of the uncertainties as obtained by the fit.

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Measurement of single top-quark production in the s-channel in proton$-$proton collisions at $\mathrm{\sqrt{s}=13}$ TeV with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Braden Keim ; Abbott, D.C. ; et al.
JHEP 06 (2023) 191, 2023.
Inspire Record 2153660 DOI 10.17182/hepdata.133620

A measurement of single top-quark production in the s-channel is performed in proton$-$proton collisions at a centre-of-mass energy of 13 TeV with the ATLAS detector at the CERN Large Hadron Collider. The dataset corresponds to an integrated luminosity of 139 fb$^{-1}$. The analysis is performed on events with an electron or muon, missing transverse momentum and exactly two $b$-tagged jets in the final state. A discriminant based on matrix element calculations is used to separate single-top-quark s-channel events from the main background contributions, which are top-quark pair production and $W$-boson production in association with jets. The observed (expected) signal significance over the background-only hypothesis is 3.3 (3.9) standard deviations, and the measured cross-section is $\sigma=8.2^{+3.5}_{-2.9}$ pb, consistent with the Standard Model prediction of $\sigma^{\mathrm{SM}}=10.32^{+0.40}_{-0.36}$ pb.

35 data tables

Result of the s-channel single-top cross-section measurement, in pb. The statistical and systematic uncertainties are given, as well as the total uncertainty. The normalisation factors for the $t\bar{t}$ and $W$+jets backgrounds are also shown, with their total uncertainties.

Distribution of ${E}_{T}^{miss}$ after the fit of the multijet backgrounds, in the electron channel, in the signal region, without applying the cut on ${E}_{T}^{miss}$. Simulated events are normalised to the expected number of events given the integrated luminosity, after applying the normalisation factors obtained in the multijet fit. The last bin includes the overflow. The uncertainty band indicates the simulation's statistical uncertainty, the normalisation uncertainties for different processes ($40$ % for $W$+jets production, $30$ % for multijet background and $6$ % for top-quark processes) and the multijet background shape uncertainty in each bin, summed in quadrature. The lower panel of the figure shows the ratio of the data to the prediction.

Distribution of ${E}_{T}^{miss}$ after the fit of the multijet backgrounds, in the electron channel, in the $W$+jets VR, without applying the cut on ${E}_{T}^{miss}$. Simulated events are normalised to the expected number of events given the integrated luminosity, after applying the normalisation factors obtained in the multijet fit. The last bin includes the overflow. The uncertainty band indicates the simulation's statistical uncertainty, the normalisation uncertainties for different processes ($40$ % for $W$+jets production, $30$ % for multijet background and $6$ % for top-quark processes) and the multijet background shape uncertainty in each bin, summed in quadrature. The lower panel of the figure shows the ratio of the data to the prediction.

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Pseudorapidity distribution of charged hadrons in proton-proton collisions at $\sqrt{s}$ = 13 TeV

The CMS collaboration Khachatryan, Vardan ; Sirunyan, Albert M ; Tumasyan, Armen ; et al.
Phys.Lett.B 751 (2015) 143-163, 2015.
Inspire Record 1384119 DOI 10.17182/hepdata.69375

The pseudorapidity distribution of charged hadrons in pp collisions at sqrt(s) =13 TeV is measured using a data sample obtained with the CMS detector, operated at zero magnetic field, at the CERN LHC. The yield of primary charged long-lived hadrons produced in inelastic pp collisions is determined in the central region of the CMS pixel detector (abs(eta)<2) using both hit pairs and reconstructed tracks. For central pseudorapidities (abs(eta)<0.5), the charged-hadron multiplicity density is dN/d(eta)[charged,abs(eta) < 0.5] = 5.49 +/- 0.01 (stat) +/- 0.17 (sys), a value obtained by combining the two methods. The result is compared to predictions from Monte Carlo event generators and to similar measurements made at lower collision energies.

1 data table

Distribution of the pseudorapidity density of charged hadrons in the region $|\eta|<2$ in inelastic pp collisions are 13 TeV.


Effect of event selection on jetlike correlation measurement in $d$+Au collisions at $\sqrt{s_{\rm{NN}}}=200$ GeV

The STAR collaboration Adamczyk, L. ; Adkins, J.K. ; Agakishiev, G. ; et al.
Phys.Lett.B 743 (2015) 333-339, 2015.
Inspire Record 1335765 DOI 10.17182/hepdata.73235

Dihadron correlations are analyzed in $\sqrt{s_{_{\rm NN}}} = 200$ GeV $d$+Au collisions classified by forward charged particle multiplicity and zero-degree neutral energy in the Au-beam direction. It is found that the jetlike correlated yield increases with the event multiplicity. After taking into account this dependence, the non-jet contribution on the away side is minimal, leaving little room for a back-to-back ridge in these collisions.

16 data tables

The dihadron correlated yield normalized per radian per unit of pseudorapidity as function of $\Delta\eta$ in d+Au collisions on the near (|$\Delta\phi$| < $\pi$/3). Shown is the low FTPC-Au activity data. Trigger and associated particles have 1 < $p_T$ < 3 GeV/c and |$\eta$| < 1.

The dihadron correlated yield normalized per radian per unit of pseudorapidity as function of $\Delta\eta$ in d+Au collisions on the away side (|$\Delta\phi$ - $\pi$| < $\pi$/3. Shown is the high FTPC-Au activity data. Trigger and associated particles have 1 < $p_T$ < 3 GeV/c and |$\eta$| < 1.

The dihadron correlated yield normalized per radian per unit of pseudorapidity as function of $\Delta\eta$ in d+Au collisions on the near (|$\Delta\phi$| < $\pi$/3) side. Shown is the high-activity data after subtracting the unscaled. Trigger and associated particles have 1 < $p_T$ < 3 GeV/c and |$\eta$| < 1.

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Measurement of the forward charged particle pseudorapidity density in pp collisions at sqrt(s) = 8 TeV using a displaced interaction point

The TOTEM collaboration Antchev, G. ; Aspell, P. ; Atanassov, I. ; et al.
Eur.Phys.J.C 75 (2015) 126, 2015.
Inspire Record 1328627 DOI 10.17182/hepdata.72847

The the pseudorapidity density of charged particles dN$_{ch}$/d$\eta$ is measured by the TOTEM experiment in pp collisions at √s = 8 TeV within the range 3.9 < $\eta$ < 4.7 and −6.95 < $\eta$ < −6.9. Data were collected in a low intensity LHC run with collisions occurring at a distance of 11.25 m from the nominal interaction point. The data sample is expected to include 96-97% of the inelastic proton-proton interactions. The measurement reported here considers charged particles with $P_T$ > 0 MeV/c, produced in inelastic interactions with at least one charged particle in −7 < $\eta$ < −6 or 3.7< $\eta$ < 4.8. The dN$_{ch}$/d$\eta$ has been found to decrease with |$\eta$|, from 5.11 ± 0.73 at $\eta$ =3.95 to 1.81 ± 0.56 at $\eta$ = −6.925. Several MC generators are compared to the data and are found to be within the systematic uncertainty of the measurement.

1 data table

The TOTEM dNch/deta measurement for inelastic pp events with displaced interaction point at 8 TeV.


Measurement of pseudorapidity distributions of charged particles in proton-proton collisions at $\sqrt{s}$ = 8 TeV by the CMS and TOTEM experiments

The CMS & TOTEM collaborations Chatrchyan, Serguei ; Khachatryan, Vardan ; Sirunyan, Albert M ; et al.
Eur.Phys.J.C 74 (2014) 3053, 2014.
Inspire Record 1294140 DOI 10.17182/hepdata.66893

Pseudorapidity (eta) distributions of charged particles produced in proton-proton collisions at a centre-of-mass energy of 8 TeV are measured in the ranges abs(eta) < 2.2 and 5.3 < abs(eta) < 6.4 covered by the CMS and TOTEM detectors, respectively. The data correspond to an integrated luminosity of 45 inverse microbarns. Measurements are presented for three event categories. The most inclusive category is sensitive to 91-96% of the total inelastic proton-proton cross section. The other two categories are disjoint subsets of the inclusive sample that are either enhanced or depleted in single diffractive dissociation events. The data are compared to models used to describe high-energy hadronic interactions. None of the models considered provide a consistent description of the measured distributions.

3 data tables

Charged particle multiplicity (Inclusive) -- syst -- BB: bin-by-bin uncertainty.

Charged particle multiplicity (Non Single Diffractive dissociation (NSD) enhanced) -- syst -- BB: bin-by-bin uncertainty.

Charged particle multiplicity (Single Diffractive dissociation (SD) enhanced) -- syst -- BB: bin-by-bin uncertainty.


Measurement of Charged Particle Spectra in Deep-Inelastic ep Scattering at HERA

The H1 collaboration Alexa, C. ; Andreev, V. ; Baghdasaryan, A. ; et al.
Eur.Phys.J.C 73 (2013) 2406, 2013.
Inspire Record 1217865 DOI 10.17182/hepdata.62615

Charged particle production in deep-inelastic ep scattering is measured with the H1 detector at HERA. The kinematic range of the analysis covers low photon virtualities, 5<Q (2)<100 GeV(2), and small values of Bjorken-x, 10(−4)<x<10(−2). The analysis is performed in the hadronic centre-of-mass system. The charged particle densities are measured as a function of pseudorapidity (η (∗)) and transverse momentum ( ) in the range 0<η (∗)<5 and in bins of x and Q (2). The data are compared to predictions from different Monte Carlo generators implementing various options for hadronisation and parton evolutions.

36 data tables

Charged particle density as a function of pseudorapidity for the PT range 0-1 GeV in the HCM frame.

Charged particle density as a function of pseudorapidity for the PT range 1-10 GeV in the HCM frame.

Charged particle density as a function of pseudorapidity for the PT interval 0-1 GeV in fixed Q**2 and X intervals in the HCM frame.

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Measurement of the forward charged particle pseudorapidity density in pp collisions at sqrt{s} = 7 TeV with the TOTEM experiment

The TOTEM collaboration Antchev, G ; Atanassov, I. ; Avati, V. ; et al.
EPL 98 (2012) 31002, 2012.
Inspire Record 1115294 DOI 10.17182/hepdata.59403

The TOTEM experiment has measured the charged particle pseudorapidity density dN_{ch}/deta in pp collisions at sqrt{s} = 7 TeV for 5.3<|eta|<6.4 in events with at least one charged particle with transverse momentum above 40 MeV/c in this pseudorapidity range. This extends the analogous measurement performed by the other LHC experiments to the previously unexplored forward eta region. The measurement refers to more than 99% of non-diffractive processes and to single and double diffractive processes with diffractive masses above ~3.4 GeV/c^2, corresponding to about 95% of the total inelastic cross-section. The dN_{ch}/deta has been found to decrease with |eta|, from 3.84 pm 0.01(stat) pm 0.37(syst) at |eta| = 5.375 to 2.38 pm 0.01(stat) pm 0.21(syst) at |eta| = 6.375. Several MC generators have been compared to data; none of them has been found to fully describe the measurement.

1 data table

Charged-particle multiplicities in proton-proton collisions at a centre-of mass energy of 7 TeV as a function of pseudorapidity for events with the number of charged particles >=1 having transverse momentum >40 MeV and 5.3< absolute(pseudorapidity) <6.5.


Dependence on pseudorapidity and centrality of charged hadron production in PbPb collisions at a nucleon-nucleon centre-of-mass energy of 2.76 TeV

The CMS collaboration Chatrchyan, Serguei ; Khachatryan, Vardan ; Sirunyan, Albert M ; et al.
JHEP 08 (2011) 141, 2011.
Inspire Record 919733 DOI 10.17182/hepdata.58223

A measurement is presented of the charged hadron multiplicity in hadronic PbPb collisions, as a function of pseudorapidity and centrality, at a collision energy of 2.76 TeV per nucleon pair. The data sample is collected using the CMS detector and a minimum-bias trigger, with the CMS solenoid off. The number of charged hadrons is measured both by counting the number of reconstructed particle hits and by forming hit doublets of pairs of layers in the pixel detector. The two methods give consistent results. The charged hadron multiplicity density dN(ch)/d eta, evaluated at eta=0 for head-on collisions, is found to be 1612 +/- 55, where the uncertainty is dominated by systematic effects. Comparisons of these results to previous measurements and to various models are also presented.

3 data tables

The measured charged hadron multiplicity density as a function of the centrality.

The measured charged hadron multiplicity density divided by Npart/2 as a function of the pseudorapidity in 4 centrality bins.

The measured charged hadron multiplicity density at pseudorapidiy=0 divided by Npart/2 as a function of the number of participants.


Charged-particle multiplicities in pp interactions measured with the ATLAS detector at the LHC

The ATLAS collaboration Aad, G. ; Abbott, B. ; Abdallah, J. ; et al.
New J.Phys. 13 (2011) 053033, 2011.
Inspire Record 882098 DOI 10.17182/hepdata.57077

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.

41 data tables

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.

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