Measurement of the dineutrino system kinematic variables in dileptonic top quark pair production in proton-proton collisions at$\sqrt{s}$ = 13 TeV

The CMS collaboration Chekhovsky, Vladimir ; Hayrapetyan, Aram ; Makarenko, Vladimir ; et al.
CMS-TOP-24-001, 2025.
Inspire Record 3006250 DOI 10.17182/hepdata.153302

Differential top quark pair production cross sections are measured in the dilepton final states e$^+$e$^-$, $μ^+μ^-$, and e$^\pmμ^\mp$, as a function of kinematic variables of the two-neutrino system: the transverse momentum $p_\mathrm{T}^{νν}$ of the dineutrino system, the minimum distance in azimuthal angle between $\vec{p}_\mathrm{T}^{\,νν}$ and leptons, and in two dimensions in bins of both observables. The measurements are performed using CERN LHC proton-proton collisions at $\sqrt{s}$ = 13 TeV, recorded by the CMS detector between 2016 and 2018, corresponding to an integrated luminosity of 138 fb$^{-1}$. The measured cross sections are unfolded to the particle level using an unregularized least squares method. Results are compared with predictions by the standard model of particle physics, and found to be in agreement with theoretical calculations as well as Monte Carlo simulations.

43 data tables

Data and MC simulation yields after the event selection, combined for all data-taking periods and split by channels. The uncertainties on the expected yields include systematic and statistical uncertainties. The relative contribution in percent of each process to the total expected yield of a channel is given in parentheses.

Observed (black markers) and expected distributions of leading lepton $p_{T}$ after event selection. The hatched (grey) areas denote the systematic (total) uncertainties in the expected yields. Events from all data-taking periods and all channels are combined. The lower panel of each plot shows the ratio between observed and expected distributions. The last bin includes all events above the plotted range. The entry Background corresponds to the sum of all the SM predictions.

Observed (black markers) and expected distributions of leading jet $p_{T}$ after event selection. The hatched (grey) areas denote the systematic (total) uncertainties in the expected yields. Events from all data-taking periods and all channels are combined. The lower panel of each plot shows the ratio between observed and expected distributions. The last bin includes all events above the plotted range. The entry Background corresponds to the sum of all the SM predictions.

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Dielectron production in Au$+$Au collisions at $\sqrt{s_{NN}}$=200 GeV

The PHENIX collaboration Adare, A. ; Aidala, C. ; Ajitanand, N.N. ; et al.
Phys.Rev.C 93 (2016) 014904, 2016.
Inspire Record 1393530 DOI 10.17182/hepdata.143067

We present measurements of $e^+e^-$ production at midrapidity in Au$+$Au collisions at $\sqrt{s_{_{NN}}}$ = 200 GeV. The invariant yield is studied within the PHENIX detector acceptance over a wide range of mass ($m_{ee} <$ 5 GeV/$c^2$) and pair transverse momentum ($p_T$ $<$ 5 GeV/$c$), for minimum bias and for five centrality classes. The \ee yield is compared to the expectations from known sources. In the low-mass region ($m_{ee}=0.30$--0.76 GeV/$c^2$) there is an enhancement that increases with centrality and is distributed over the entire pair \pt range measured. It is significantly smaller than previously reported by the PHENIX experiment and amounts to $2.3\pm0.4({\rm stat})\pm0.4({\rm syst})\pm0.2^{\rm model}$ or to $1.7\pm0.3({\rm stat})\pm0.3({\rm syst})\pm0.2^{\rm model}$ for minimum bias collisions when the open-heavy-flavor contribution is calculated with {\sc pythia} or {\sc mc@nlo}, respectively. The inclusive mass and $p_T$ distributions as well as the centrality dependence are well reproduced by model calculations where the enhancement mainly originates from the melting of the $\rho$ meson resonance as the system approaches chiral symmetry restoration. In the intermediate-mass region ($m_{ee}$ = 1.2--2.8 GeV/$c^2$), the data hint at a significant contribution in addition to the yield from the semileptonic decays of heavy-flavor mesons.

2 data tables

Cocktail of hadronic sources for the 2010 run using the PYTHIA generator for the open heavy flavor contributions.

Invariant mass spectrum of $e^+e^-$ pairs in MB Au+Au collisions within the PHENIX acceptance compared to the cocktail of expected decays.


Heavy-quark production and elliptic flow in Au$+$Au collisions at $\sqrt{s_{_{NN}}}=62.4$ GeV

The PHENIX collaboration Adare, A. ; Aidala, C. ; Ajitanand, N.N. ; et al.
Phys.Rev.C 91 (2015) 044907, 2015.
Inspire Record 1296108 DOI 10.17182/hepdata.143115

We present measurements of electrons and positrons from the semileptonic decays of heavy-flavor hadrons at midrapidity ($|y|<$ 0.35) in Au$+$Au collisions at $\sqrt{s_{_{NN}}}=62.4$ GeV. The data were collected in 2010 by the PHENIX experiment that included the new hadron-blind detector. The invariant yield of electrons from heavy-flavor decays is measured as a function of transverse momentum in the range $1<p_T^e<5$ GeV/$c$. The invariant yield per binary collision is slightly enhanced above the $p$$+$$p$ reference in Au$+$Au 0%--20%, 20%--40% and 40%--60% centralities at a comparable level. This may be a result of the interplay between initial-state Cronin effects, final-state flow, and energy loss for heavy-quark production at this low beam energy. The $v_2$ of electrons from heavy-flavor decays is nonzero when averaged between $1.3<p_T^e<2.5$ GeV/$c$ from $0<{\rm centrality}<40$% collisions at $\sqrt{s_{_{NN}}}=62.4$ GeV. For 20%--40% centrality collisions, the $v_2$ at $\sqrt{s_{_{NN}}}=62.4$ GeV is smaller than that for heavy flavor decays at $\sqrt{s_{_{NN}}}=200$ GeV. The $v_2$ of the electrons from heavy-flavor decay at the lower beam energy is also smaller than $v_2$ for pions. Both results indicate that the heavy-quarks interact with the medium formed in these collisions, but they may not be at the same level of thermalization with the medium as observed at $\sqrt{s_{_{NN}}}=200$ GeV.

14 data tables

Invariant yield of candidate electrons measured in Au+Au collisions at $\sqrt{s_{NN}}$=62.4 GeV for different centrality bins. The yields are scaled by powers of 10 for clarity. The systematic uncertainty is shown as boxes and is, in many cases, comparable to the symbol size.

Cocktail prediction for photonic electron invariant yield. Invariant yield of (black dots) candidate electrons and (solid lines) electrons calculated from different photonic sources in Au+Au collisions at $\sqrt{s_{NN}}$=62.4 GeV for MB events.

Invariant yield of heavy-flavor electrons measured in Au+Au collisions at $\sqrt{s_{NN}}$ = 62.4 GeV for different centrality bins. The yields are scaled by powers of 10 for clarity. The uncertainty bars (boxes) show the statistical (systematic) uncertainties.

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