Search for the $Z\gamma$ decay mode of new high-mass resonances in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Braden Keim ; Abeling, Kira ; et al.
Phys.Lett.B 848 (2024) 138394, 2024.
Inspire Record 2695554 DOI 10.17182/hepdata.141854

This letter presents a search for narrow, high-mass resonances in the $Z\gamma$ final state with the $Z$ boson decaying into a pair of electrons or muons. The $\sqrt{s}=13$ TeV $pp$ collision data were recorded by the ATLAS detector at the CERN Large Hadron Collider and have an integrated luminosity of 140 fb$^{-1}$. The data are found to be in agreement with the Standard Model background expectation. Upper limits are set on the resonance production cross section times the decay branching ratio into $Z\gamma$. For spin-0 resonances produced via gluon-gluon fusion, the observed limits at 95% confidence level vary between 65.5 fb and 0.6 fb, while for spin-2 resonances produced via gluon-gluon fusion (or quark-antiquark initial states) limits vary between 77.4 (76.1) fb and 0.6 (0.5) fb, for the mass range from 220 GeV to 3400 GeV.

6 data tables

The main sources of systematic uncertainty for the $X\to Z \gamma$ search. The gluon-gluon fusion spin-0 signal samples produced at $m_{X} = [220-3400]$ GeV are used to evaluate the systematic uncertainty. The ranges for the uncertainties span the variations among different categories and different $m_{X}$ resonance masses. The uncertainty due to the spurious signal uncertainty is reported as the absolute number of events. In the table, "ID" for photon and electrons refers to identification efficiency uncertainties, "ISO" refers to isolation efficiency uncertainties, "TRIG" refers to trigger efficiency uncertainties, "RECO" refers to muon reconstruction efficiency uncertainty and "TTVA" refers to muon track-to-vertex-association efficiency uncertainty.

The observed (expected) upper limits of $\sigma(pp\to X)\cdot\mathcal{B}(X\to Z\gamma)$ for spin-0 and spin-2 heavy resonances at 95\% CL. $m_{X}$ varies from 220 GeV to 3400~\GeV.

Impacts of grouped dominant systematic uncertainties. The impact corresponds to the relative variation of the asymptotic expected upper limit of $\sigma(pp \rightarrow X) \times BR(X \rightarrow Z\gamma)$ from $m_{X}=220$ GeV to $m_{X}=3.4$ TeV when re-evaluating the quantity by fixing the corresponding nuisance parameters to the best-fit values, while keeping others free to float. The impact of total systematic uncertainties are performed in the last row.

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Measurement of the low-energy antitriton inelastic cross section

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Phys.Lett.B 848 (2024) 138337, 2024.
Inspire Record 2675130 DOI 10.17182/hepdata.145643

In this Letter, the first measurement of the inelastic cross section for antitriton$-$nucleus interactions is reported, covering the momentum range of $0.8 \leq p < 2.4$ GeV/$c$. The measurement is carried out using data recorded with the ALICE detector in pp and Pb$-$Pb collisions at a centre-of-mass energy per nucleon of 13 TeV and 5.02 TeV, respectively. The detector material serves as an absorber for antitriton nuclei. The raw yield of (anti)triton nuclei measured with the ALICE apparatus is compared to the results from detailed ALICE simulations based on the GEANT4 toolkit for the propagation of (anti)particles through matter, allowing one to quantify the inelastic interaction probability in the detector material. This analysis complements the measurement of the inelastic cross section of antinuclei up to $A=3$ carried out by the ALICE Collaboration, and demonstrates the feasibility of the study of the isospin dependence of inelastic interaction cross section with the analysis techniques presented in this Letter.

10 data tables

Raw primary antitriton-to-triton ratio as a function of the momentum p_primary in exp. data.

Raw primary antitriton-to-triton ratio as a function of the momentum p_primary in MC (sigma_inel x 0.75).

Raw primary antitriton-to-triton ratio as a function of the momentum p_primary in MC (sigma_inel x 1.0).

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Strong constraints on jet quenching in centrality-dependent $p$+Pb collisions at 5.02 TeV from ATLAS

The ATLAS collaboration Aad, Georges ; Abbott, Braden Keim ; Abbott, D.C. ; et al.
Phys.Rev.Lett. 131 (2023) 072301, 2023.
Inspire Record 2090791 DOI 10.17182/hepdata.130943

Jet quenching is the process of color-charged partons losing energy via interactions with quark-gluon plasma droplets created in heavy-ion collisions. The collective expansion of such droplets is well described by viscous hydrodynamics. Similar evidence of collectivity is consistently observed in smaller collision systems, including $pp$ and $p$+Pb collisions. In contrast, while jet quenching is observed in Pb+Pb collisions, no evidence has been found in these small systems to date, raising fundamental questions about the nature of the system created in these collisions. The ATLAS experiment at the Large Hadron Collider has measured the yield of charged hadrons correlated with reconstructed jets in 0.36 nb$^{-1}$ of $p$+Pb and 3.6 pb$^{-1}$ of $pp$ collisions at 5.02 TeV. The yields of charged hadrons with $p_\mathrm{T}^\mathrm{ch} >0.5$ GeV near and opposite in azimuth to jets with $p_\mathrm{T}^\mathrm{jet} > 30$ or $60$ GeV, and the ratios of these yields between $p$+Pb and $pp$ collisions, $I_{p\mathrm{Pb}}$, are reported. The collision centrality of $p$+Pb events is categorized by the energy deposited by forward neutrons from the struck nucleus. The $I_{p\mathrm{Pb}}$ values are consistent with unity within a few percent for hadrons with $p_\mathrm{T}^\mathrm{ch} >4$ GeV at all centralities. These data provide new, strong constraints which preclude almost any parton energy loss in central $p$+Pb collisions.

8 data tables

The per-jet charged particle yield in pPb and pp collisions for hadrons near a $p_{T}^{\textrm{jet}} > 30~\textrm{GeV}$ jet ($\Delta\phi_{\textrm{ch,jet}} < \pi/8$).

The per-jet charged particle yield in pPb and pp collisions for hadrons opposite to a $p_{T}^{\textrm{jet}} > 30~\textrm{GeV}$ jet ($\Delta\phi_{\textrm{ch,jet}} > 7\pi/8$).

The per-jet charged particle yield in pPb and pp collisions for hadrons near a $p_{T}^{\textrm{jet}} > 60~\textrm{GeV}$ jet ($\Delta\phi_{\textrm{ch,jet}} < \pi/8$).

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First measurement of the absorption of $^{3}\overline{\rm He}$ nuclei in matter and impact on their propagation in the galaxy

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Nature Phys. 19 (2023) 61-71, 2023.
Inspire Record 2026264 DOI 10.17182/hepdata.133480

In our Galaxy, light antinuclei composed of antiprotons and antineutrons can be produced through high-energy cosmic-ray collisions with the interstellar medium or could also originate from the annihilation of dark-matter particles that have not yet been discovered. On Earth, the only way to produce and study antinuclei with high precision is to create them at high-energy particle accelerators. Although the properties of elementary antiparticles have been studied in detail, the knowledge of the interaction of light antinuclei with matter is limited. We determine the disappearance probability of $^{3}\overline{\rm He}$ when it encounters matter particles and annihilates or disintegrates within the ALICE detector at the Large Hadron Collider. We extract the inelastic interaction cross section, which is then used as input to calculations of the transparency of our Galaxy to the propagation of $^{3}\overline{\rm He}$ stemming from dark-matter annihilation and cosmic-ray interactions within the interstellar medium. For a specific dark-matter profile, we estimate a transparency of about 50%, whereas it varies with increasing $^{3}\overline{\rm He}$ momentum from 25% to 90% for cosmic-ray sources. The results indicate that $^{3}\overline{\rm He}$ nuclei can travel long distances in the Galaxy, and can be used to study cosmic-ray interactions and dark-matter annihilation.

21 data tables

Raw primary antihelium3-to-helium3 ratio as a function of the momentum p_primary.

Raw primary antihelium3-to-helium3 ratio from Geant4-based MC simulations as a function of the momentum p_primary with default sigma_inel(3Hebar).

Raw primary antihelium3-to-helium3 ratio from Geant4-based MC simulations as a function of the momentum p_primary with sigma_inel(3Hebar)x0.5.

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Version 2
K$^{0}_{\rm S}$- and (anti-)$\Lambda$-hadron correlations in pp collisions at $\sqrt{s} = 13$ TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Eur.Phys.J.C 81 (2021) 945, 2021.
Inspire Record 1891391 DOI 10.17182/hepdata.114015

Two-particle azimuthal correlations are measured with the ALICE apparatus in pp collisions at $\sqrt{s} = 13$ TeV to explore strangeness- and multiplicity-related effects in the fragmentation of jets and the transition regime between bulk and hard production, probed with the condition that a strange meson (K$^{0}_{\rm S}$) or baryon ($\Lambda$) with transverse momentum $p_{\rm T} > 3$ GeV/c is produced. Azimuthal correlations between kaons or $\Lambda$ hyperons with other hadrons are presented at midrapidity for a broad range of the trigger ($3 < p_{\rm T}^{\rm trigg} < 20$ GeV/$c$) and associated particle $p_{\rm T}$ (1 GeV/$c$$< p_{\rm T}^{\rm assoc} < p_{\rm T}^{\rm trigg}$), for minimum-bias events and as a function of the event multiplicity. The near- and away-side peak yields are compared for the case of either K$^{0}_{\rm S}$ or $\Lambda$($\overline{\Lambda}$) being the trigger particle with that of inclusive hadrons (a sample dominated by pions). In addition, the measurements are compared with predictions from PYTHIA 8 and EPOS LHC event generators.

162 data tables

Two-dimensional $K_S^0$-h correlation function with $3<p_{\mathrm{T}}^{\mathrm{trigg}}< 4 \mathrm{GeV}/c$ and $1 \mathrm{GeV}/c<p_{\mathrm{T}}^{\mathrm{assoc}}< p_{\mathrm{T}}^{\mathrm{trigg}} $

Two-dimensional $K_S^0$-h correlation function with $3<p_{\mathrm{T}}^{\mathrm{trigg}}< 4 \mathrm{GeV}/c$ and $1 \mathrm{GeV}/c<p_{\mathrm{T}}^{\mathrm{assoc}}< p_{\mathrm{T}}^{\mathrm{trigg}} $

$\Delta\varphi$ projection of h-h correlation function with $3<p_{\mathrm{T}}^{\mathrm{trigg}}< 4 \mathrm{GeV}/c$ and $1 \mathrm{GeV}/c<p_{\mathrm{T}}^{\mathrm{assoc}}< p_{\mathrm{T}}^{\mathrm{trigg}} $

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Measurement of the average very forward energy as a function of the track multiplicity at central pseudorapidities in proton-proton collisions at $\sqrt{s} =$ 13 TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Eur.Phys.J.C 79 (2019) 893, 2019.
Inspire Record 1747892 DOI 10.17182/hepdata.91963

The average total energy as well as its hadronic and electromagnetic components are measured with the CMS detector at pseudorapidities $-$6.6 $<\eta<-$5.2 in proton-proton collisions at a centre-of-mass energy $\sqrt{s}=$ 13 TeV. The results are presented as a function of the charged particle multiplicity in the region $|\eta|< $2. This measurement is sensitive to correlations induced by the underlying event structure over a very wide pseudorapidity region. The predictions of Monte Carlo event generators commonly used in collider experiments and ultra-high energy cosmic ray physics are compared to the data.

5 data tables

Average total energy reconstructed in the region −6.6 < eta < −5.2 as a function of the number of reconstructed tracks for abs(eta)<2.

Average total energiy reconstructed in the region −6.6 < eta < −5.2 normalised to that in the first bin (Nch< 10) as a function of the number of reconstructed tracks for abs(eta)<2.

Average electromagnetic energy reconstructed in the region −6.6 < eta < −5.2 as a function of the number of reconstructed tracks for abs(eta)<2.

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Multiplicity dependence of light-flavor hadron production in pp collisions at $\sqrt{s}$ = 7 TeV

The ALICE collaboration Acharya, Shreyasi ; Torales - Acosta, Fernando ; Adamova, Dagmar ; et al.
Phys.Rev.C 99 (2019) 024906, 2019.
Inspire Record 1684320 DOI 10.17182/hepdata.84282

Comprehensive results on the production of unidentified charged particles, $\pi^{\pm}$, $\rm{K}^{\pm}$, $\rm{K}^{0}_{S}$, $\rm{K}$*(892)$^{0}$, $\rm{p}$, $\overline{\rm{p}}$, $\phi$(1020), $\Lambda$, $\overline{\Lambda}$, $\Xi^{-}$, $\overline{\Xi}^{+}$, $\Omega^{-}$ and $\overline{\Omega}^{+}$ hadrons in proton-proton (pp) collisions at $\sqrt{s}$ = 7 TeV at midrapidity ($|y| < 0.5$) as a function of charged-particle multiplicity density are presented. In order to avoid auto-correlation biases, the actual transverse momentum ($p_{\rm{T}}$) spectra of the particles under study and the event activity are measured in different rapidity windows. In the highest multiplicity class, the charged-particle density reaches about 3.5 times the value measured in inelastic collisions. While the yield of protons normalized to pions remains approximately constant as a function of multiplicity, the corresponding ratios of strange hadrons to pions show a significant enhancement that increases with increasing strangeness content. Furthermore, all identified particle to pion ratios are shown to depend solely on charged-particle multiplicity density, regardless of system type and collision energy. The evolution of the spectral shapes with multiplicity and hadron mass shows patterns that are similar to those observed in p-Pb and Pb-Pb collisions at LHC energies. The obtained $p_{\rm{T}}$ distributions and yields are compared to expectations from QCD-based pp event generators as well as to predictions from thermal and hydrodynamic models. These comparisons indicate that traces of a collective, equilibrated system are already present in high-multiplicity pp collisions.

106 data tables

Transverse momentum spectra of charged particles in V0M I multiplicity class

Transverse momentum spectra of charged particles in V0M II multiplicity class

Transverse momentum spectra of charged particles in V0M III multiplicity class

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Correlated long-range mixed-harmonic fluctuations measured in $pp$, $p$+Pb and low-multiplicity Pb+Pb collisions with the ATLAS detector

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
Phys.Lett.B 789 (2019) 444-471, 2019.
Inspire Record 1681154 DOI 10.17182/hepdata.83969

Correlations of two flow harmonics $v_n$ and $v_m$ via three- and four-particle cumulants are measured in 13 TeV $pp$, 5.02 TeV $p$+Pb, and 2.76 TeV peripheral Pb+Pb collisions with the ATLAS detector at the LHC. The goal is to understand the multi-particle nature of the long-range collective phenomenon in these collision systems. The large non-flow background from dijet production present in the standard cumulant method is suppressed using a method of subevent cumulants involving two, three and four subevents separated in pseudorapidity. The results show a negative correlation between $v_2$ and $v_3$ and a positive correlation between $v_2$ and $v_4$ for all collision systems and over the full multiplicity range. However, the magnitudes of the correlations are found to depend strongly on the event multiplicity, the choice of transverse momentum range and collision system. The relative correlation strength, obtained by normalisation of the cumulants with the $\langle v_n^2\rangle$ from a two-particle correlation analysis, is similar in the three collision systems and depends weakly on the event multiplicity and transverse momentum. These results based on the subevent methods provide strong evidence of a similar long-range multi-particle collectivity in $pp$, $p$+Pb and peripheral Pb+Pb collisions.

60 data tables

The symmetric cumulant $sc_{2,3}\{4\}$ results as a function of multiplicity ($N_{ch}$) in pp collisions at $\sqrt{s_{NN}}$ = 13 TeV

The symmetric cumulant $sc_{2\,3}\{4\}$ results as a function of multiplicity ($N_{ch}$) in pp collisions at $\sqrt{s_{NN}}$ = 13 TeV

The symmetric cumulant $sc_{2\,3}\{4\}$ results as a function of multiplicity ($N_{ch}$) in pPb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV

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Measurement of the Inelastic Proton-Proton Cross Section at $\sqrt{s} = 13$ TeV with the ATLAS Detector at the LHC

The ATLAS collaboration Aaboud, M. ; Aad, Georges ; Abbott, Brad ; et al.
Phys.Rev.Lett. 117 (2016) 182002, 2016.
Inspire Record 1468167 DOI 10.17182/hepdata.74822

This Letter presents a measurement of the inelastic proton-proton cross section using 60 $\mu$b$^{-1}$ of $pp$ collisions at a center-of-mass energy $\sqrt{s}$ of $13$ TeV with the ATLAS detector at the LHC. Inelastic interactions are selected using rings of plastic scintillators in the forward region ($2.07<|\eta|<3.86$) of the detector. A cross section of $68.1\pm 1.4$ mb is measured in the fiducial region $\xi=M_X^2/s>10^{-6}$, where $M_X$ is the larger invariant mass of the two hadronic systems separated by the largest rapidity gap in the event. In this $\xi$ range the scintillators are highly efficient. For diffractive events this corresponds to cases where at least one proton dissociates to a system with $M_X>13$ GeV. The measured cross section is compared with a range of theoretical predictions. When extrapolated to the full phase space, a cross-section of $78.1 \pm 2.9$ mb is measured, consistent with the inelastic cross section increasing with center-of-mass energy.

1 data table

The measured and extrapolated inelastic cross section. The statistical uncertainty is negligible and is therefore displayed as zero. The first systematic uncertainty is the experimental systematic uncertainty apart from the luminosity, the second is the luminosity uncertainty, and the third is the extrapolation uncertainty.


Rapidity gap cross sections measured with the ATLAS detector in pp collisions at sqrt(s) = 7 TeV

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abdallah, Jalal ; et al.
Eur.Phys.J.C 72 (2012) 1926, 2012.
Inspire Record 1084540 DOI 10.17182/hepdata.58497

Pseudorapidity gap distributions in proton-proton collisions at sqrt(s) = 7 TeV are studied using a minimum bias data sample with an integrated luminosity of 7.1 inverse microbarns. Cross sections are measured differentially in terms of Delta eta F, the larger of the pseudorapidity regions extending to the limits of the ATLAS sensitivity, at eta = +/- 4.9, in which no final state particles are produced above a transverse momentum threshold p_T Cut. The measurements span the region 0 < Delta eta F < 8 for 200 < p_T Cut < 800 MeV. At small Delta eta F, the data test the reliability of hadronisation models in describing rapidity and transverse momentum fluctuations in final state particle production. The measurements at larger gap sizes are dominated by contributions from the single diffractive dissociation process (pp -> Xp), enhanced by double dissociation (pp -> XY) where the invariant mass of the lighter of the two dissociation systems satisfies M_Y <~ 7 GeV. The resulting cross section is d sigma / d Delta eta F ~ 1 mb for Delta eta F >~ 3. The large rapidity gap data are used to constrain the value of the pomeron intercept appropriate to triple Regge models of soft diffraction. The cross section integrated over all gap sizes is compared with other LHC inelastic cross section measurements.

5 data tables

The inelastic cross section differential in the forward rapidity gap size, DELTA(C=RAPGAP) for a maximum observed particle transverse momentum of 200 MeV in the gap.

The inelastic cross section differential in the forward rapidity gap size, DELTA(C=RAPGAP) for a maximum observed particle transverse momentum of 400 MeV in the gap.

The inelastic cross section differential in the forward rapidity gap size, DELTA(C=RAPGAP) for a maximum observed particle transverse momentum of 600 MeV in the gap.

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