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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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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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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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

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
JHEP 07 (2018) 161, 2018.
Inspire Record 1653948 DOI 10.17182/hepdata.83970

A measurement of the inelastic proton-proton cross section with the CMS detector at a center-of-mass energy of $\sqrt{s} =$ 13 TeV is presented. The analysis is based on events with energy deposits in the forward calorimeters, which cover pseudorapidities of -6.6 $&lt; \eta $ 4.1 GeV and/or $M_\mathrm{Y} &gt;$ 13 GeV, where $M_\mathrm{X}$ and $M_\mathrm{Y}$ are the masses of the diffractive dissociation systems at negative and positive pseudorapidities, respectively. The results are compared with those from other experiments as well as to predictions from high-energy hadron-hadron interaction models.

1 data table

The measured fiducial cross sections. The first bin represents the $\xi > 10^{-6}$ region, while the second bin represents the extended $\xi_{X} > 10^{-7}$ or $\xi_{Y} > 10^{-6}$ result. The first uncertainty is the systematic uncertainty excluding luminosity, the second is the luminosity uncertainty.


Study of jet quenching with isolated-photon+jet correlations in PbPb and pp collisions at $\sqrt{s_{_{\mathrm{NN}}}} =$ 5.02 TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Phys.Lett.B 785 (2018) 14-39, 2018.
Inspire Record 1638996 DOI 10.17182/hepdata.80815

Measurements of azimuthal angle and transverse momentum ($p_\mathrm{T}$) correlations of isolated photons and associated jets are reported for pp and PbPb collisions at $\sqrt{s_{_{\mathrm{NN}}}} =$ 5.02 TeV. The data were recorded with the CMS detector at the CERN LHC. For events containing a leading isolated photon with $p_\mathrm{T}^\gamma >$ 40 GeV$/c$ and an associated jet with $p_\mathrm{T}^\text{jet} >$ 30 GeV$/c$, the photon+jet azimuthal correlation and $p_\mathrm{T}$ imbalance in PbPb collisions are studied as functions of collision centrality and $p_\mathrm{T}^\gamma$. The results are compared to pp reference data collected at the same collision energy and to predictions from several theoretical models for parton energy loss. No evidence of broadening of the photon+jet azimuthal correlations is observed, while the ratio $p_\mathrm{T}^\text{jet}/p_\mathrm{T}^\gamma$ decreases significantly for PbPb data relative to the pp reference. All models considered agree within uncertainties with the data. The number of associated jets per photon with $p_\mathrm{T}^\gamma >$ 80 GeV$/c$ is observed to be shifted towards lower $p_\mathrm{T}^\text{jet}$ values in central PbPb collisions compared to pp collisions.

7 data tables

Jet resolution parameters for pp and PbPb collisions in various centrality bins.

The azimuthal correlation of photons and jets in five $p_{\mathrm{T}}^{\gamma}$ intervals for 0-30% and 30-100% centrality PbPb collisions. The smeared pp data are included for comparison.

Distribution of $x_{\mathrm{j}\gamma} = p_{\mathrm{T}}^{\mathrm{jet}} / p_{\mathrm{T}}^{\gamma}$ in five $p_{\mathrm{T}}^{\gamma}$ intervals for 0-30% and 30-100% centrality PbPb collisions. The smeared pp data are included for comparison. Empty bins are denoted as 'empty' in the table.

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Version 2
Constraining gluon distributions in nuclei using dijets in proton-proton and proton-lead collisions at $\sqrt{s_{_\mathrm{NN}}} =$ 5.02 TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
Phys.Rev.Lett. 121 (2018) 062002, 2018.
Inspire Record 1672941 DOI 10.17182/hepdata.83198

The pseudorapidity distributions of dijets as a function of their average transverse momentum ($p_\mathrm{T}^\text{ave}$) are measured in proton-lead (pPb) and proton-proton (pp) collisions. The data samples were collected by the CMS experiment at the CERN LHC, at a nucleon-nucleon center-of-mass energy of 5.02 TeV. A significant modification of the pPb spectra with respect to the pp spectra is observed in all $p_\mathrm{T}^\text{ave}$ intervals investigated. The ratios of the pPb and pp distributions are compared to next-to-leading order perturbative quantum chromodynamics calculations with unbound nucleon and nuclear parton distribution functions (PDFs). These results give the first evidence that the gluon PDF at large Bjorken $x$ in lead ions is strongly suppressed with respect to the PDF in unbound nucleons.

42 data tables

The ratio of pPb to pp $\eta_{\mathrm{dijet}}$ spectra for dijets in the range $55 < p_{\mathrm{T}}^{\mathrm{ave}} < 75$ GeV.

The ratio of pPb to pp $\eta_{\mathrm{dijet}}$ spectra for dijets in the range $55 < p_{\mathrm{T}}^{\mathrm{ave}} < 75$ GeV.

The ratio of pPb to pp $\eta_{\mathrm{dijet}}$ spectra for dijets in the range $75 < p_{\mathrm{T}}^{\mathrm{ave}} < 95$ GeV.

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Measurement of the inclusive energy spectrum in the very forward direction in proton-proton collisions at sqrt(s)=13 TeV

The CMS collaboration Sirunyan, Albert M ; Tumasyan, Armen ; Adam, Wolfgang ; et al.
JHEP 08 (2017) 046, 2017.
Inspire Record 1511284 DOI 10.17182/hepdata.76842

The differential cross section for inclusive particle production as a function of energy in proton-proton collisions at a center-of-mass energy of 13 TeV is measured in the very forward region of the CMS detector. The measurement is based on data collected with the CMS apparatus at the LHC, and corresponds to an integrated luminosity of 0.35 inverse microbarns. The energy is measured in the CASTOR calorimeter, which covers the pseudorapidity region -6.6 < eta < -5.2. The results are given as a function of the total energy deposited in CASTOR, as well as of its electromagnetic and hadronic components. The spectra are sensitive to the modeling of multiparton interactions in pp collisions, and provide new constraints for hadronic interaction models used in collider and in high energy cosmic ray physics.

6 data tables

Differential cross section as a function of the electromagnetic energy in the region −6.6 < eta < −5.2 for events with xi>10−6.

Differential cross section as a function of the total energy in the region −6.6 < eta < −5.2 for events with xi>10−6.

Differential cross section as a function of the hadronic energy in the region −6.6 < eta < −5.2 for events with xi>10−6.

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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.


Production of leading charged particles and leading charged-particle jets at small transverse momenta in pp collisions at sqrt(s) = 8 TeV

The CMS collaboration Khachatryan, Vardan ; Sirunyan, Albert M ; Tumasyan, Armen ; et al.
Phys.Rev.D 92 (2015) 112001, 2015.
Inspire Record 1380605 DOI 10.17182/hepdata.70721

The per-event yield of the highest transverse momentum charged particle and charged-particle jet, integrated above a given pt(min) threshold starting at pt(min) = 0.8 and 1 GeV, respectively, is studied in pp collisions at sqrt(s) = 8 TeV. The particles and the jets are measured in the pseudorapidity ranges abs(eta) < 2.4 and 1.9, respectively. The data are sensitive to the momentum scale at which parton densities saturate in the proton, to multiple partonic interactions, and to other key aspects of the transition between the soft and hard QCD regimes in hadronic collisions.

2 data tables

Charged particles within $|\eta| < 2.4$ with $N_{ch}(p_T>40\;MeV)>0$ in $5.3<|\eta|<6.5$.

Charged particle jets within $|\eta| < 1.9$ with anti-kt (R=0.5) and $N_{ch}(p_T>40\;MeV)>0$ in $5.3<|\eta|<6.5$.