First measurement of $\Lambda_c$ baryon production in Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 200 GeV

The STAR collaboration Adam, Jaroslav ; Adamczyk, Leszek ; Adams, Joseph ; et al.
Phys.Rev.Lett. 124 (2020) 172301, 2020.
Inspire Record 1762441 DOI 10.17182/hepdata.94228

We report on the first measurement of the charmed baryon $\Lambda_c^{\pm}$ production at midrapidity ($|y|$ $<$ 1) in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV collected by the STAR experiment at the Relativistic Heavy Ion Collider. The $\Lambda_c$/$D^0$ (denoting ($\Lambda_c^++\Lambda_c^-$)/($D^0+\bar{D^0}$)) yield ratio is measured to be 1.08 $\pm$ 0.16 (stat.) $\pm$ 0.26 (sys.) in the 0--20% most central Au+Au collisions for the transverse momentum ($p_T$) range 3 $<$ $p_T$ $<$ 6 GeV/$c$. This is significantly larger than the PYTHIA model calculations for $p+p$ collisions. The measured $\Lambda_c$/$D^0$ ratio, as a function of $p_T$ and collision centrality, is comparable to the baryon-to-meson ratios for light and strange hadrons in Au+Au collisions. Model calculations including coalescence hadronization for charmed baryon and meson formation reproduce the features of our measured $\Lambda_c$/$D^0$ ratio.

7 data tables

The $pK\pi$ invariant mass distributions (Counts per 10 MeV/c^2 bin) for right-sign combinations in Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 200\,GeV for 0--20\% centrality class.

The $pK\pi$ invariant mass distributions (Counts per 10 MeV/c^2 bin) for wrong-sign combinations, scaled by 1/3, in Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 200\,GeV for 0--20\% centrality class.

The $pK\pi$ invariant mass distributions (Counts per 10 MeV/c^2 bin) for right-sign combinations in Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 200\,GeV for 10--80\% centrality class.

More…

Discovery reach for wino and higgsino dark matter with a disappearing track signature at a 100 TeV $pp$ collider

Saito, Masahiko ; Sawada, Ryu ; Terashi, Koji ; et al.
Eur.Phys.J.C 79 (2019) 469, 2019.
Inspire Record 1713045 DOI 10.17182/hepdata.90451

Within the theory of supersymmetry, the lightest neutralino is a dark matter candidate and is often assumed to be the lightest supersymmetric particle (LSP) as well. If the neutral wino or higgsino is dark matter, the upper limit of the LSP mass is determined by the observed relic density of dark matter. If the LSP is a nearly-pure neutral state of the wino or higgsino, the lightest chargino state is expected to have a significant lifetime due to a tiny mass difference between the LSP and the chargino. This article presents discovery potential of the 100 TeV future circular hadron collider (FCC) for the wino and higgsino dark matter using a disappearing-track signature. The search strategy to extend the discovery reach to the thermal limits of wino/higgsino dark matter is discussed with detailed studies on the background rate and the reference design of the FCC-hadron detector under possible running scenarios of the FCC-hadron machine. A proposal of modifying the detector layout and several ideas to improve the sensitivity further are also discussed.

14 data tables

One of three barrel inner-tracker layouts considered in this study; the default layout $\#$1. The contour drawn behind the layouts shows the number of chargino decays in 3 TeV wino signal events with 30 ab$^{-1}$ at a given position. The analysis considers the region $|\eta|<1$, denoted by the dotted lines.

Leading jet $p_{T}$ distributions after removing events containing isolated leptons with 30 ab$^{-1}$ at $\sqrt{s}=100$ TeV. The SM backgrounds from $W/Z$+jets and top production processes are shown as filled histograms. Also shown as dashed (dotted) line is the 3 (1) TeV wino (higgsino) signal scaled up by a factor 1000.

$E_{\text{T}}^{\text{miss}}$ distributions after removing events containing isolated leptons with 30 ab$^{-1}$ at $\sqrt{s}=100$ TeV. The SM backgrounds from $W/Z$+jets and top production processes are shown as filled histograms. Also shown as dashed (dotted) line is the 3 (1) TeV wino (higgsino) signal scaled up by a factor 1000.

More…

Search for heavy resonances decaying into a photon and a hadronically decaying Higgs boson in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abbott, Dale Charles ; et al.
Phys.Rev.Lett. 125 (2020) 251802, 2020.
Inspire Record 1811594 DOI 10.17182/hepdata.95538

This Letter presents a search for the production of new heavy resonances decaying into a Higgs boson and a photon using proton-proton collision data at $\sqrt{s}=13$ TeV collected by the ATLAS detector at the LHC. The data correspond to an integrated luminosity of 139 fb$^{-1}$. The analysis is performed by reconstructing hadronically decaying Higgs boson $(H\to b\bar{b})$ candidates as single large-radius jets. A novel algorithm using information about the jet constituents in the center-of-mass frame of the jet is implemented to identify the two $b$-quarks in the single jet. No significant excess of events is observed above the expected background. Upper limits are set on the production cross-section times branching fraction for narrow spin-1 resonances decaying into a Higgs boson and a photon in the resonance mass range from 0.7 to 4 TeV, cross-sections times branching fraction are excluded between 11.6 fb and 0.11 fb at a 95% confidence level.

5 data tables

Data distribution of the reconstructed $m_{J\gamma}$ and background only fitting in the single-b-tagged category. Background and signal fit functions are provided in Table 3. Background event yields are calculated using the fitted background function.

Data distribution of the reconstructed $m_{J\gamma}$ and background only fitting in the double-b-tagged category. Background and signal fit functions are provided in Table 3. Background event yields are calculated using the fitted background function.

Background and signal functions, with their fit parameters. For the background function, the parameters are fitted from the data distribution. The "Yield" is the total number of events in data in the single-b-tagged or double-b-tagged fitting range. For the single-b-tagged category, the fitting range is [1400GeV, 4200GeV], and for the double-b-tagged category, it is [600GeV, 4200GeV]. The background event yields per bin in Table 1 and Table 2 are calculated using the data yield multiplied by the integral of the normalized background function in that bin. For the signal function, the value for the parameters are from parametrisation studies and CB stands for a Crystal-Ball function. Signal distributions in Figure 1a and Figure 1b are normalized to an arbitrary yield, for illustration purpose.

More…

Low-$p_T$ $e^{+}e^{-}$ pair production in Au$+$Au collisions at $\sqrt{s_{NN}}$ = 200 GeV and U$+$U collisions at $\sqrt{s_{NN}}$ = 193 GeV at STAR

The STAR collaboration Adam, Jaroslav ; Adamczyk, Leszek ; Adams, Joseph ; et al.
Phys.Rev.Lett. 121 (2018) 132301, 2018.
Inspire Record 1676541 DOI 10.17182/hepdata.84821

We report first measurements of $e^{+}e^{-}$ pair production in the mass region 0.4 $

36 data tables

The centrality dependence of e+e− invariant mass spectra within the STAR acceptance from Au+Au collisions and U+U collisions for pair pT < 0.15 GeV/c. The vertical bars on data points depict the statistical uncertainties, while the systematic uncertainties are shown as gray boxes. The hadronic cocktail yields from U+U collisions are ∼5%–12% higher than those from Au+Au collisions in given centrality bins; thus only cocktails for Au+Au collisions are shown here as solid lines, with shaded bands representing the systematic uncertainties for clarity.

The centrality dependence of e+e− invariant mass spectra within the STAR acceptance from Au+Au collisions and U+U collisions for pair pT < 0.15 GeV/c. The vertical bars on data points depict the statistical uncertainties, while the systematic uncertainties are shown as gray boxes. The hadronic cocktail yields from U+U collisions are ∼5%–12% higher than those from Au+Au collisions in given centrality bins; thus only cocktails for Au+Au collisions are shown here as solid lines, with shaded bands representing the systematic uncertainties for clarity.

The centrality dependence of e+e− invariant mass spectra within the STAR acceptance from Au+Au collisions and U+U collisions for pair pT < 0.15 GeV/c. The vertical bars on data points depict the statistical uncertainties, while the systematic uncertainties are shown as gray boxes. The hadronic cocktail yields from U+U collisions are ∼5%–12% higher than those from Au+Au collisions in given centrality bins; thus only cocktails for Au+Au collisions are shown here as solid lines, with shaded bands representing the systematic uncertainties for clarity.

More…

Version 2
Search for direct stau production in events with two hadronic $\tau$-leptons in $\sqrt{s} = 13$ TeV $pp$ collisions with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abbott, Dale Charles ; et al.
Phys.Rev.D 101 (2020) 032009, 2020.
Inspire Record 1765529 DOI 10.17182/hepdata.92006

A search for the direct production of the supersymmetric partners of $\tau$-leptons (staus) in final states with two hadronically decaying $\tau$-leptons is presented. The analysis uses a dataset of $pp$ collisions corresponding to an integrated luminosity of $139$ fb$^{-1}$, recorded with the ATLAS detector at the Large Hadron Collider at a center-of-mass energy of 13 TeV. No significant deviation from the expected Standard Model background is observed. Limits are derived in scenarios of direct production of stau pairs with each stau decaying into the stable lightest neutralino and one $\tau$-lepton in simplified models where the two stau mass eigenstates are degenerate. Stau masses from 120 GeV to 390 GeV are excluded at 95% confidence level for a massless lightest neutralino.

52 data tables

The observed upper limits on the model cross-section in units of pb for simplified models with combined ${\tilde{\tau}}^{+}_{R,L} {\tilde{\tau}}^{-}_{R,L}$ production. Three points at ${M({\tilde{\chi}}^{0}_{1})}=200GeV$ were removed from the plot but kept in the table because they overlapped with the plot's legend and are far from the exclusion contour.

The observed upper limits on the model cross-section in units of pb for simplified models with combined ${\tilde{\tau}}^{+}_{R,L} {\tilde{\tau}}^{-}_{R,L}$ production. Three points at ${M({\tilde{\chi}}^{0}_{1})}=200GeV$ were removed from the plot but kept in the table because they overlapped with the plot's legend and are far from the exclusion contour.

The observed upper limits on the model cross-section in units of pb for simplified models with ${\tilde{\tau}}_L {\tilde{\tau}}_L$ only production. Three points at $M({\tilde{\chi}}^{0}_{1})=200GeV$ were removed from the plot but kept in the table because they overlapped with the plot's legend and are far from the exclusion contour.

More…

Version 2
Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in $\sqrt{s}$ = 13 TeV $pp$ collisions with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abbott, Dale Charles ; et al.
Phys.Rev.D 101 (2020) 072001, 2020.
Inspire Record 1771533 DOI 10.17182/hepdata.91127

A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell $W$ and $Z$ bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of $\sqrt{s}$ = 13 TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb$^{-1}$. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015-2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full dataset are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV.

58 data tables

Distributions in SR-low of the data and post-fit background prediction for m<sub>T</sub>. The SR-low event selections are applied for each distribution except for the variable shown, where the selection is indicated by a red arrow. The normalization factor for the WZ background is derived from the background-only estimation described in Section 7. The expected distribution for a benchmark signal model is included for comparison. The first (last) bin includes underflow (overflow). The "Top-quark like" category contains the tt&#772;, Wt, and WW processes while the "Others" category contains backgrounds from triboson production and processes that include a Higgs boson, 3 or more tops, and tops produced in association with W or Z bosons. The bottom panel shows the ratio of the data to the post-fit background prediction. The hatched bands indicate the combined theoretical, experimental, and MC statistical uncertainties.

Distributions in SR-low of the data and post-fit background prediction for m<sub>T</sub>. The SR-low event selections are applied for each distribution except for the variable shown, where the selection is indicated by a red arrow. The normalization factor for the WZ background is derived from the background-only estimation described in Section 7. The expected distribution for a benchmark signal model is included for comparison. The first (last) bin includes underflow (overflow). The "Top-quark like" category contains the tt&#772;, Wt, and WW processes while the "Others" category contains backgrounds from triboson production and processes that include a Higgs boson, 3 or more tops, and tops produced in association with W or Z bosons. The bottom panel shows the ratio of the data to the post-fit background prediction. The hatched bands indicate the combined theoretical, experimental, and MC statistical uncertainties.

Distributions in SR-low of the data and post-fit background prediction for H<sup>boost</sup>. The SR-low event selections are applied for each distribution except for the variable shown, where the selection is indicated by a red arrow. The normalization factor for the WZ background is derived from the background-only estimation described in Section 7. The expected distribution for a benchmark signal model is included for comparison. The first (last) bin includes underflow (overflow). The "Top-quark like" category contains the tt&#772;, Wt, and WW processes while the "Others" category contains backgrounds from triboson production and processes that include a Higgs boson, 3 or more tops, and tops produced in association with W or Z bosons. The bottom panel shows the ratio of the data to the post-fit background prediction. The hatched bands indicate the combined theoretical, experimental, and MC statistical uncertainties.

More…

Measurement of the associated production of a Higgs boson decaying into $b$-quarks with a vector boson at high transverse momentum in $pp$ collisions at $\sqrt{s} = 13$ TeV with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abbott, Dale Charles ; et al.
Phys.Lett.B 816 (2021) 136204, 2021.
Inspire Record 1810348 DOI 10.17182/hepdata.94801

The associated production of a Higgs boson with a $W$ or $Z$ boson decaying into leptons and where the Higgs boson decays to a $b\bar{b}$ pair is measured in the high vector-boson transverse momentum regime, above 250 GeV, with the ATLAS detector. 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 $0.72 ^{+0.39}_{-0.36}$ corresponding to an observed (expected) significance of 2.1 (2.7) standard deviations. Cross-sections of associated production of a Higgs boson decaying into $b$ quark pairs with a $W$ or $Z$ gauge boson, decaying into leptons, are measured in two exclusive vector boson transverse momentum regions, 250-400 GeV and above 400 GeV, and interpreted as constraints on anomalous couplings in the framework of a Standard Model effective field theory.

3 data tables

Observed correlations between the measured reduced stage-1.2 simplified template VH, V->leptons and H->bb cross sections, including both the statistical and systematic uncertainties.

Measured and predicted VH, V->leptons reduced stage-1.2 simplified template cross sections times the H->bb and V->leptons branching fractions with corresponding uncertainties. All possible Z decays into neutral and charged leptons are considered.

Linear combinations of Wilson coefficients corresponding to the principal component decomposition eigenvectors. The corresponding eigenvalues, representing in the gaussian approximation the inverse uncertainty square of the measured eigenvector, is also indicated.


Version 2
Measurement of the jet mass distribution and top quark mass in hadronic decays of boosted top quarks in pp collisions at $\sqrt{s} =$ 13 TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Phys.Rev.Lett. 124 (2020) 202001, 2020.
Inspire Record 1764472 DOI 10.17182/hepdata.93067

A measurement is reported of the jet mass distribution in hadronic decays of boosted top quarks produced in pp collisions at $\sqrt{s} =$ 13 TeV. The data were collected with the CMS detector at the LHC and correspond to an integrated luminosity of 35.9 fb$^{-1}$. The measurement is performed in the lepton+jets channel of $\mathrm{t\bar{t}}$ events, where the lepton is an electron or muon. The products of the hadronic top quark decay t $\to$ bW $\to$ bq$\mathrm{\bar{q}}'$ are reconstructed as a single jet with transverse momentum larger than 400 GeV. The $\mathrm{t\bar{t}}$ cross section as a function of the jet mass is unfolded at the particle level and used to extract a value of the top quark mass of 172.6 $\pm$ 2.5 GeV. A novel jet reconstruction technique is used for the first time at the LHC, which improves the precision by a factor of three relative to an earlier measurement. This highlights the potential of measurements using boosted top quarks, where the new technique will enable future precision measurements.

17 data tables

Reconstructed distribution of $m_\mathrm{jet}$ after the full event selection in the lepton+jets channel.

The particle-level $\mathrm{t}\overline{\mathrm{t}}$ differential cross section in the fiducial region as a function of the XCone-jet mass.

The particle-level $\mathrm{t}\overline{\mathrm{t}}$ differential cross section in the fiducial region as a function of the XCone-jet mass.

More…

Identified particle production, azimuthal anisotropy, and interferometry measurements in Au+Au collisions at $\sqrt{s_{NN}}$ = 9.2 GeV

The STAR collaboration Abelev, B.I. ; Aggarwal, M.M. ; Ahammed, Z. ; et al.
Phys.Rev.C 81 (2010) 024911, 2010.
Inspire Record 831944 DOI 10.17182/hepdata.93265

We present the first measurements of identified hadron production, azimuthal anisotropy, and pion interferometry from Au+Au collisions below the nominal injection energy at the Relativistic Heavy-Ion Collider (RHIC) facility. The data were collected using the large acceptance STAR detector at $\sqrt{s_{NN}}$ = 9.2 GeV from a test run of the collider in the year 2008. Midrapidity results on multiplicity density (dN/dy) in rapidity (y), average transverse momentum (<pT>), particle ratios, elliptic flow, and HBT radii are consistent with the corresponding results at similar $\sqrt{s_{NN}}$ from fixed target experiments. Directed flow measurements are presented for both midrapidity and forward rapidity regions. Furthermore the collision centrality dependence of identified particle dN/dy, <pT>, and particle ratios are discussed. These results also demonstrate the readiness of the STAR detector to undertake the proposed QCD critical point search and the exploration of the QCD phase diagram at RHIC.

27 data tables

Second order event plane resolution measured in the TPC as a function of collision centrality for.

Efficiency × acceptance for reconstructed pions, kaons, and protons in the TPC as a function of p_T at midrapidity.

Percentage of pion background contribution estimated from HIJING+GEANT as a function of p_T at midrapidity.

More…

Measurement of the azimuthal anisotropy of $\Upsilon$(1S) and $\Upsilon$(2S) mesons in PbPb collisions at $\sqrt{s_\mathrm{NN}} =$ 5.02 TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Phys.Lett.B 819 (2021) 136385, 2021.
Inspire Record 1801111 DOI 10.17182/hepdata.93880

The second-order Fourier coefficients ($v_2$) characterizing the azimuthal distribution of $\Upsilon$(1S) and $\Upsilon$(2S) mesons arising from PbPb collisions at $\sqrt{s_\mathrm{NN}} =$ 5.02 TeV are studied. The $\Upsilon$ mesons are reconstructed in their dimuon decay channel, as measured by the CMS detector. The data set corresponds to an integrated luminosity of 1.7 nb$^{-1}$. The scalar product method is used to extract the $v_2$ coefficients of the azimuthal distribution. Results are reported for the rapidity range $|y|$$\lt$ 2.4, with the transverse momentum 0 $\lt$$p_\mathrm{T}$$\lt$ 50 GeV/$c$, and in three centrality ranges of 10-30%, 30-50% and 50-90%. In contrast to the J/$\psi$ mesons, the measured $v_2$ values for the $\Upsilon$ mesons are found to be consistent with zero.

5 data tables

$v_{2}$ of $\Upsilon(\mathrm{1S})$ mesons as a function of collision centrality.

$v_{2}$ of $\Upsilon(\mathrm{1S})$ and $\Upsilon(\mathrm{2S})$ mesons integrated for 10-90% centrality range.

$v_{2}$ of $\Upsilon(\mathrm{1S})$ as a function of $p_{\mathrm{T}}$ in 10-90% centrality range.

More…