Date

Measurement of the impact-parameter dependent azimuthal anisotropy in coherent $\rho^0$ photoproduction in Pb$-$Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Agarwal, Apar ; et al.
Phys.Lett.B 858 (2024) 139017, 2024.
Inspire Record 2789555 DOI 10.17182/hepdata.154177

This Letter presents the first measurement of the impact-parameter dependent angular anisotropy in the decay of coherently photoproduced $\rho^0$ mesons. The $\rho^0$ mesons are reconstructed through their decay into pion pairs. The measured anisotropy corresponds to the amplitude of the $\cos(2\phi)$ modulation, where $\phi$ is the angle between the two vectors formed by the sum and the difference of the transverse momenta of the pions, respectively. The measurement was performed by the ALICE Collaboration at the LHC using data from ultraperipheral Pb$-$Pb collisions at a center-of-mass energy of $\sqrt{s_{\mathrm{NN}}}~=~5.02$ TeV per nucleon pair. Different impact-parameter regions are selected by classifying the events in nuclear-breakup classes. The amplitude of the $\cos(2\phi)$ modulation is found to increase by about one order of magnitude from large to small impact parameters. Theoretical calculations describe the measured $\cos(2\phi)$ anisotropy and its impact-parameter dependence as the result of a quantum interference effect at the femtometer scale, arising from the ambiguity regarding which of the nuclei is the photon source in the interaction.

1 data table

Amplitudes of the $\cos(2\phi)$ modulation of the $ρ^0$ yield in ultra-peripheral Pb--Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV in all neutron classes.


Measurements of Z bosons plus jets using variables sensitive to double parton scattering in pp collisions at 13 TeV

The CMS collaboration Tumasyan, Armen ; Adam, Wolfgang ; Andrejkovic, Janik Walter ; et al.
JHEP 10 (2021) 176, 2021.
Inspire Record 1866118 DOI 10.17182/hepdata.110665

Double-parton scattering is investigated using events with a Z boson and jets. The Z boson is reconstructed using only the dimuon channel. The measurements are performed with proton-proton collision data recorded by the CMS experiment at the LHC at $\sqrt{s} =$ 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{-1}$ collected in the year 2016. Differential cross sections of Z + $\geq$ 1 jet and Z + $\geq$ 2 jets are measured with transverse momentum of the jets above 20 GeV and pseudorapidity $|\eta|$$\lt$ 2.4. Several distributions with sensitivity to double-parton scattering effects are measured as functions of the angle and the transverse momentum imbalance between the Z boson and the jets. The measured distributions are compared with predictions from several event generators with different hadronization models and different parameter settings for multiparton interactions. The measured distributions show a dependence on the hadronization and multiparton interaction simulation parameters, and are important input for future improvements of the simulations.

25 data tables

Differential cross sections as function of Delta Phi between Z boson and the leading jet for Z+ ≥ 1 jet events.

Differential cross sections as function of transverse momentum imbalance between Z boson and the leading jet for Z+ ≥ 1 jet events.

Differential cross sections as function of Delta Phi between Z boson and dijet for Z+ ≥ 2 jets events.

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Study of hard double-parton scattering in four-jet events in $pp$ collisions at $\sqrt{s} = 7$ TeV with the ATLAS experiment

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
JHEP 11 (2016) 110, 2016.
Inspire Record 1479760 DOI 10.17182/hepdata.73908

Inclusive four-jet events produced in proton-proton collisions at a centre-of-mass energy of $\sqrt{s} = 7$ TeV are analysed for the presence of hard double-parton scattering using data corresponding to an integrated luminosity of 37.3 pb$^{-1}$, collected with the ATLAS detector at the LHC. The contribution of hard double-parton scattering to the production of four-jet events is extracted using an artificial neural network, assuming that hard double-parton scattering can be approximated by an uncorrelated overlaying of dijet events. For events containing at least four jets with transverse momentum $p_{\mathrm{T}} \geq 20$ GeV and pseudorapidity $\eta \leq 4.4$, and at least one having $p_{\mathrm{T}} \geq 42.5$ GeV, the contribution of hard double-parton scattering is estimated to be $f_{\mathrm{DPS}} = 0.092 ^{+0.005}_{-0.011} (\mathrm{stat.}) ^{+0.033}_{-0.037} (\mathrm{syst.})$. After combining this measurement with those of the inclusive dijet and four-jet cross-sections in the appropriate phase space regions, the effective overlap area between the interacting protons, $\sigma_{\mathrm{eff}}$, was determined to be $\sigma_{\mathrm{eff}} = 14.9 ^{+1.2}_{-1.0} (\mathrm{stat.}) ^{+5.1}_{-3.8} (\mathrm{syst.})$ mb. This result is consistent within the quoted uncertainties with previous measurements of $\sigma_{\mathrm{eff}}$, performed at centre-of-mass energies between 63 GeV and 8 TeV using various final states, and it corresponds to $21^{+7}_{-6}$% of the total inelastic cross-section measured at $\sqrt{s} = 7$ TeV. The distributions of the observables sensitive to the contribution of hard double-parton scattering, corrected for detector effects, are also provided.

21 data tables

Normalized distribution of the variable $\Delta^{p_{\mathrm{T}}}_{34}$, defined in Eq (16) of the paper, in data after unfolding to particle level.

Normalized distribution of the variable $\Delta\phi_{34}$, defined in Eq (16) of the paper, in data after unfolding to particle level.

Normalized distribution of the variable $\Delta^{p_{\mathrm{T}}}_{12}$, defined in Eq (16) of the paper, in data after unfolding to particle level.

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Measurement of the $b\overline{b}$ dijet cross section in $pp$ collisions at $\sqrt{s} = 7$ TeV with the ATLAS detector

The ATLAS collaboration Aaboud, Morad ; Aad, Georges ; Abbott, Brad ; et al.
Eur.Phys.J.C 76 (2016) 670, 2016.
Inspire Record 1478355 DOI 10.17182/hepdata.75316

The dijet production cross section for jets containing a $b$-hadron ($b$-jets) has been measured in proton-proton collisions with a centre-of-mass energy of $\sqrt{s} = 7$ TeV, using the ATLAS detector at the LHC. The data used correspond to an integrated luminosity of 4.2 fb$^{-1}$. The cross section is measured for events with two identified $b$-jets with a transverse momentum $p_T > 20$ GeV and a minimum separation in the $\eta$-$\phi$ plane of $\Delta R = 0.4$. At least one of the jets in the event is required to have $p_T > 270$ GeV. The cross section is measured differentially as a function of dijet invariant mass, dijet transverse momentum, boost of the dijet system, and the rapidity difference, azimuthal angle and angular distance between the $b$-jets. The results are compared to different predictions of leading order and next-to-leading order perturbative quantum chromodynamics matrix elements supplemented with models for parton-showers and hadronization.

6 data tables

Results for the m_bb distribution. Statistical and systematic uncertainties are quoted.

Results for the DeltaPhi distribution. Statistical and systematic uncertainties are quoted.

Results for the y* distribution. Statistical and systematic uncertainties are quoted.

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Measurement of the forward Z boson production cross-section in pp collisions at $\sqrt{s} = 13$ TeV

The LHCb collaboration Aaij, Roel ; Adeva, Bernardo ; Adinolfi, Marco ; et al.
JHEP 09 (2016) 136, 2016.
Inspire Record 1477581 DOI 10.17182/hepdata.110162

A measurement of the production cross-section of Z bosons in pp collisions at $\sqrt{s} = 13$ TeV is presented using dimuon and dielectron final states in LHCb data. The cross-section is measured for leptons with pseudorapidities in the range $2.0 < \eta < 4.5$, transverse momenta $p_\text{T} > 20$ GeV and dilepton invariant mass in the range $60

15 data tables

The FSR correction applied as a function of the boson rapidity for muons.

The FSR correction applied as a function of the boson rapidity for electrons.

The FSR correction applied as a function of $\phi ^ * _ \eta$ for muons.

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Measurement of total and differential $W^+W^-$ production cross sections in proton-proton collisions at $\sqrt{s}=$ 8 TeV with the ATLAS detector and limits on anomalous triple-gauge-boson couplings

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abdallah, Jalal ; et al.
JHEP 09 (2016) 029, 2016.
Inspire Record 1426515 DOI 10.17182/hepdata.76808

The production of $W$ boson pairs in proton-proton collisions at $\sqrt{s}=$ 8 TeV is studied using data corresponding to 20.3 fb$^{-1}$ of integrated luminosity collected by the ATLAS detector during 2012 at the CERN Large Hadron Collider. The $W$ bosons are reconstructed using their leptonic decays into electrons or muons and neutrinos. Events with reconstructed jets are not included in the candidate event sample. A total of 6636 $WW$ candidate events are observed. Measurements are performed in fiducial regions closely approximating the detector acceptance. The integrated measurement is corrected for all acceptance effects and for the $W$ branching fractions to leptons in order to obtain the total $WW$ production cross section, which is found to be 71.1$\pm1.1$(stat)$^{+5.7}_{-5.0}$(syst)$\pm1.4$ pb. This agrees with the next-to-next-to-leading-order Standard Model prediction of 63.2$^{+1.6}_{-1.4}$(scale)$\pm1.2$(PDF) pb. Fiducial differential cross sections are measured as a function of each of six kinematic variables. The distribution of the transverse momentum of the leading lepton is used to set limits on anomalous triple-gauge-boson couplings.

29 data tables

Measured production cross sections of WW production in the fiducial region for different final states corresponding to different W decay channels: both W's decaying into electrons or both decaying to muon. The cross sections are defined for direct decays of the W bosons into prompt electrons or muons, intermediate decays into tau leptons are disregarded. The electrons are required to be contained within abs(eta)<2.47 and to lie outside of 1.37 < abs(eta) < 1.53, muons are required to lie within abs(eta)<2.4. The leading and subleading leptons in the events are required to have a transverse momentum above 25 and 20 GeV respectively. The transverse momentum of the vectorial sum of the neutrinos in the event should be larger than 45 GeV (PT(C=SUM(NU))). The transverse momentum of the vectorial sum of the neutrinos multiplied by the sine of azimuthal difference between lepton and the vectorial sum of the neutrinos in the event should be larger than 45 GeV if the azimuthal difference between lepton and the vectorial sum of the neutrinos is smaller than PI/2. The invariant mass of the leptons should exceed 15 GeV. The absolute difference between the invariant mass of the leptons and the mass of the Z boson should be larger than 15 GeV. Particle-level jets are defined using the anti-kT algorithm with radius of 0.4. No jets above 25 GeV and within abs(eta)<4.5 are allowed in the event. Both, resonant and non-resonant WW production processes, are included in the cross sections.

Measured production cross section of WW production in the fiducial region in case one W boson decays into a prompt electron and the other one into a prompt muon. The cross section is defined for direct decays of the W bosons into prompt electrons or muons, intermediate decays into tau leptons are disregarded. The electrons are required to be contained within abs(eta)<2.47 and to lie outside of 1.37 < abs(eta) < 1.53, muons are required to lie within abs(eta)<2.4. The leading and subleading leptons in the events are required to have a transverse momentum above 25 and 20 GeV respectively. The transverse momentum of the vectorial sum of the neutrinos in the event should be larger than 20 GeV (PT(C=SUM(NU))). The transverse momentum of the vectorial sum of the neutrinos is multiplied by the sine of the azimuthal difference between lepton and the vectorial sum of the neutrinos if their azimuthal difference is smaller than PI/2. It is required to be larger than 15 GeV. The invariant mass of the leptons should exceed 10 GeV. Particle-level jets are defined using the anti-kT algorithm with radius of 0.4. No jets above 25 GeV and within abs(eta)<4.5 are allowed in the event. Both, resonant and non-resonant WW production processes, are included in the cross sections.

Measured total production cross sections of WW production in the total phase space. Both, resonant and non-resonant WW, production are considered as signal.

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Measurement of the transverse momentum and $\phi^*_{\eta}$ distributions of Drell-Yan lepton pairs in proton-proton collisions at $\sqrt{s}=8$ TeV with the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abdallah, Jalal ; et al.
Eur.Phys.J.C 76 (2016) 291, 2016.
Inspire Record 1408516 DOI 10.17182/hepdata.71339

Distributions of transverse momentum $p_T^{ll}$ and the angular variable $\phi^*_\eta$ of Drell--Yan lepton pairs are measured in 20.3 fb$^{-1}$ of proton--proton collisions at $\sqrt{s}=8$ TeV with the ATLAS detector at the LHC. Measurements in electron-pair and muon-pair final states are corrected for detector effects and combined. Compared to previous measurements in proton--proton collisions at $\sqrt{s}=7$ TeV, these new measurements benefit from a larger data sample and improved control of systematic uncertainties. Measurements are performed in bins of lepton-pair mass above, around and below the Z-boson mass peak. The data are compared to predictions from perturbative and resummed QCD calculations. For values of $\phi^*_\eta < 1$ the predictions from the Monte Carlo generator ResBos are generally consistent with the data within the theoretical uncertainties. However, at larger values of $\phi^*_\eta$ this is not generally the case. Monte Carlo generators based on the parton-shower approach are unable to describe the data over the full range of $p_T^{ll}$ and the fixed-order prediction of DYNNLO falls below the data at high values of $p_T^{ll}$. ResBos and the parton-shower Monte Carlo generators provide a much better description of the evolution of the $\phi^*_\eta$ and $p_T^{ll}$ distributions as a function of lepton-pair mass and rapidity.

41 data tables

Fiducial cross sections at Born level in the electron- and muon-pair channels as well as the combined value. The statistical and systematic uncertainties are given as a percentage of the cross section. An additional uncertainty of 2.8% on the integrated luminosity, which is fully correlated between channels and among all $m_{\ell\ell}$ bins, pertains to these measurements. The individual uncertainty sources after the combination are not necessarily orthogonal and also do not include uncertainties uncorrelated between bins of $m_{\ell\ell}$. Therefore their quadratic sum may not give the total systematic uncertainty.

The values of $(1/\sigma)\,\mathrm{d}\sigma/\mathrm{d}\phi^*_{\eta}$ in each bin of $\phi^*_{\eta}$ for the electron and muon channels separately (for various particle-level definitions) and for the Born-level combination in the kinematic region $46\textrm{ GeV} \leq m_{\ell\ell} < 66\textrm{ GeV},\ 0 \leq |y_{\ell\ell}| < 0.8$. The associated statistical and systematic (both uncorrelated and correlated between bins of $\phi^*_{\eta}$) are provided in percentage form.

The values of $(1/\sigma)\,\mathrm{d}\sigma/\mathrm{d}\phi^*_{\eta}$ in each bin of $\phi^*_{\eta}$ for the electron and muon channels separately (for various particle-level definitions) and for the Born-level combination in the kinematic region $46\textrm{ GeV} \leq m_{\ell\ell} < 66\textrm{ GeV},\ 0.8 \leq |y_{\ell\ell}| < 1.6$. The associated statistical and systematic (both uncorrelated and correlated between bins of $\phi^*_{\eta}$) are provided in percentage form.

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Measurement of forward $W$ and $Z$ boson production in $pp$ collisions at $\sqrt{s} = 8\mathrm{\,Te\kern -0.1em V}$

The LHCb collaboration Aaij, Roel ; Abellán Beteta, Carlos ; Adeva, Bernardo ; et al.
JHEP 01 (2016) 155, 2016.
Inspire Record 1406555 DOI 10.17182/hepdata.71419

Measurements are presented of electroweak boson production using data from $pp$ collisions at a centre-of-mass energy of $\sqrt{s} = 8\mathrm{\,Te\kern -0.1em V}$. The analysis is based on an integrated luminosity of $2.0\mathrm{\,fb}^{-1}$ recorded with the LHCb detector. The bosons are identified in the $W\rightarrow\mu\nu$ and $Z\rightarrow\mu^{+}\mu^{-}$ decay channels. The cross-sections are measured for muons in the pseudorapidity range $2.0 < \eta < 4.5$, with transverse momenta $p_{\rm T} > 20{\mathrm{\,Ge\kern -0.1em V\!/}c}$ and, in the case of the $Z$ boson, a dimuon mass within $60 < M_{\mu^{+}\mu^{-}} < 120{\mathrm{\,Ge\kern -0.1em V\!/}c^{2}}$. The results are \begin{align*} \sigma_{W^{+}\rightarrow\mu^{+}\nu} &= 1093.6 \pm 2.1 \pm 7.2 \pm 10.9 \pm 12.7{\rm \,pb} \, , \sigma_{W^{-}\rightarrow\mu^{-}\bar{\nu}} &= \phantom{0}818.4 \pm 1.9 \pm 5.0 \pm \phantom{0}7.0 \pm \phantom{0}9.5{\rm \,pb} \, , \sigma_{Z\rightarrow\mu^{+}\mu^{-}} &= \phantom{00}95.0 \pm 0.3 \pm 0.7 \pm \phantom{0}1.1 \pm \phantom{0}1.1{\rm \,pb} \, , \end{align*} where the first uncertainties are statistical, the second are systematic, the third are due to the knowledge of the LHC beam energy and the fourth are due to the luminosity determination. The evolution of the $W$ and $Z$ boson cross-sections with centre-of-mass energy is studied using previously reported measurements with $1.0\mathrm{\,fb}^{-1}$ of data at $7\mathrm{\,Te\kern -0.1em V}$. Differential distributions are also presented. Results are in good agreement with theoretical predictions at next-to-next-to-leading order in perturbative quantum chromodynamics.

23 data tables

Inclusive cross-section for $W^+$ and $W^-$ boson production in bins of muon pseudorapidity. The uncertainties are statistical, systematic, beam and luminosity.

Inclusive cross-section for $Z$ boson production in bins of rapidity. The uncertainties are statistical, systematic, beam and luminosity.

Inclusive cross-section for $Z$ boson production in bins of transverse momentum. The uncertainties are statistical, systematic, beam and luminosity.

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Production of associated $\Upsilon$ and open charm hadrons in $pp$ collisions at $\sqrt{s}=7$ and $8$TeV via double parton scattering

The LHCb collaboration Aaij, Roel ; Abellán Beteta, Carlos ; Adeva, Bernardo ; et al.
JHEP 07 (2016) 052, 2016.
Inspire Record 1399056 DOI 10.17182/hepdata.73583

Associated production of bottomonia and open charm hadrons in $pp$ collisions at $\sqrt{s}=7$ and $8$TeV is observed using data corresponding to an integrated luminosity of 3$fb^{-1}$ accumulated with the LHCb detector. The observation of five combinations, $\Upsilon(1S)D^0$, $\Upsilon(2S)D^0$, $\Upsilon(1S)D^+$, $\Upsilon(2S)D^+$ and $\Upsilon(1S)D^+_{s}$, is reported. Production cross-sections are measured for $\Upsilon(1S)D^0$ and $\Upsilon(1S)D^+$ pairs in the forward region. The measured cross-sections and the differential distributions indicate the dominance of double parton scattering as the main production mechanism. This allows a precise measurement of the effective cross-section for double parton scattering.

20 data tables

Normalized differential cross-section $\frac{1}{\sigma}\frac{ \mathrm{d}\sigma(\Upsilon(1S)D^0)}{\mathrm{d} p_T(\Upsilon(1S))}$ for $2<y(\Upsilon(1S))<4.5$, $2<y(D^0)<4.5$, $p_T(D^0)>1$ GeV/$c$. Only statistical uncertainties are quoted as systematic uncertainties are found to be negligible. The distribution is normalized to unity.

Normalized differential cross-section $\frac{1}{\sigma}\frac{ \mathrm{d}\sigma(\Upsilon(1S)D^+)}{\mathrm{d} p_T(\Upsilon(1S))}$ for $2<y(\Upsilon(1S))<4.5$, $2<y(D^+)<4.5$, $p_T(D^+)>1$ GeV/$c$. Only statistical uncertainties are quoted as systematic uncertainties are found to be negligible. The distribution is normalized to unity.

Normalized differential cross-section $\frac{1}{\sigma}\frac{ \mathrm{d}\sigma(\Upsilon(1S)D^0)}{\mathrm{d} p_T(D^0)}$ for $2<y(\Upsilon(1S))<4.5$, $2<y(D^0)<4.5$, $p_T(D^0)>1$ GeV/$c$. Only statistical uncertainties are quoted as systematic uncertainties are found to be negligible. The distribution is normalized to unity.

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Measurement of four-jet differential cross sections in $\sqrt{s}=8$ TeV proton-proton collisions using the ATLAS detector

The ATLAS collaboration Aad, Georges ; Abbott, Brad ; Abdallah, Jalal ; et al.
JHEP 12 (2015) 105, 2015.
Inspire Record 1394679 DOI 10.17182/hepdata.18620

Differential cross sections for the production of at least four jets have been measured in proton-proton collisions at $\sqrt{s} = 8$ TeV at the Large Hadron Collider using the ATLAS detector. Events are selected if the four anti-$k_{t}$ R=0.4 jets with the largest transverse momentum ($p_{T}$) within the rapidity range $|y|<2.8$ are well separated ($dR^{\rm min}_{4j}>0.65$), all have $p_{T}>64$ GeV, and include at least one jet with $p_{T} >100$ GeV. The dataset corresponds to an integrated luminosity of 20.3 $fb^{-1}$. The cross sections, corrected for detector effects, are compared to leading-order and next-to-leading-order calculations as a function of the jet momenta, invariant masses, minimum and maximum opening angles and other kinematic variables.

46 data tables

Measured differential four-jet cross section for R=0.4 jets, in bins of pT1, along with the uncertainties in the measurement. The events are selected using the inclusive analysis cuts. All uncertainties are given in %. The first uncertainty quoted is due to the number of data events. DSYS:mcstat is the statistical uncertainty due to the number of MC simulation events. The other columns, denoted with DSYS, correspond to the experimental systematic uncertainties arising from JES, JER, unfolding and luminosity, respectively.

Measured differential four-jet cross section for R=0.4 jets, in bins of pT2, along with the uncertainties in the measurement. The events are selected using the inclusive analysis cuts. All other details are as for pT1.

Measured differential four-jet cross section for R=0.4 jets, in bins of pT3, along with the uncertainties in the measurement. The events are selected using the inclusive analysis cuts. All other details are as for pT1.

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