W$^\pm$-boson production in p$-$Pb collisions at $\sqrt{s_{NN}} = 8.16$ TeV and PbPb collisions at $\sqrt{s_{NN}} = 5.02$ TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
JHEP 05 (2023) 036, 2023.
Inspire Record 2071184 DOI 10.17182/hepdata.133034

The production of the W$^\pm$ bosons measured in p$-$Pb collisions at a centre-of-mass energy per nucleon$-$nucleon collision $\sqrt{s_{NN}} = 8.16$ TeV and Pb$-$Pb collisions at $\sqrt{s_{NN}} = 5.02$ TeV with ALICE at the LHC is presented. The W$^\pm$ bosons are measured via their muonic decay channel, with the muon reconstructed in the pseudorapidity region $-4 < \eta^\mu_{\rm lab} < -2.5$ with transverse momentum $p_{\rm T}^\mu > 10$ GeV/$c$. While in Pb$-$Pb collisions the measurements are performed in the forward ($2.5 < y^\mu_{\rm cms} < 4$) rapidity region, in p$-$Pb collisions, where the centre-of-mass frame is boosted with respect to the laboratory frame, the measurements are performed in the backward ($-4.46 < y^\mu_{\rm cms} < -2.96$) and forward ($2.03 < y^\mu_{\rm cms} < 3.53$) rapidity regions. The W$^{-}$ and W$^{+}$ production cross sections, lepton-charge asymmetry, and nuclear modification factors are evaluated as a function of the muon rapidity. In order to study the production as a function of the p$-$Pb collision centrality, the production cross sections of the W$^{-}$ and W$^{+}$ bosons are combined and normalised to the average number of binary nucleon$-$nucleon collision $\langle N_\mathrm{coll} \rangle$. In Pb$-$Pb collisions, the same measurements are presented as a function of the collision centrality. Study of the binary scaling of the W$^\pm$-boson cross sections in p$-$Pb and Pb$-$Pb collisions is also reported. The results are compared with perturbative QCD (pQCD) calculations, with and without nuclear modifications of the Parton Distribution Functions (PDFs), as well as with available data at the LHC. Significant deviations from the theory expectations are found in the two collision systems, indicating that the measurements can provide additional constraints for the determination of nuclear PDF (nPDFs) and in particular of the light-quark distributions.

0 data tables match query

First measurement of quarkonium polarization in nuclear collisions at the LHC

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Phys.Lett.B 815 (2021) 136146, 2021.
Inspire Record 1797469 DOI 10.17182/hepdata.102403

The polarization of inclusive J/$\psi$ and $\Upsilon(1{\rm S})$ produced in Pb-Pb collisions at $\sqrt{s_{\rm{NN}}}=5.02$ TeV at the LHC is measured with the ALICE detector. The study is carried out by reconstructing the quarkonium through its decay to muon pairs in the rapidity region $2.5<y<4$ and measuring the polar and azimuthal angular distributions of the muons. The polarization parameters $\lambda_{\theta}$, $\lambda_{\phi}$ and $\lambda_{\theta\phi}$ are measured in the helicity and Collins-Soper reference frames, in the transverse momentum interval $2<p_{\rm T}<10$ GeV/$c$ and $p_{\rm T}<15$ GeV/$c$ for the J/$\psi$ and $\Upsilon(1{\rm S})$, respectively. The polarization parameters for the J/$\psi$ are found to be compatible with zero, within a maximum of about two standard deviations at low $p_{\rm T}$, for both reference frames and over the whole $p_{\rm T}$ range. The values are compared with the corresponding results obtained for pp collisions at $\sqrt{s}=7$ and 8 TeV in a similar kinematic region by the ALICE and LHCb experiments. Although with much larger uncertainties, the polarization parameters for $\Upsilon(1{\rm S})$ production in Pb-Pb collisions are also consistent with zero.

0 data tables match query

Z-boson production in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=8.16$ TeV and Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
JHEP 09 (2020) 076, 2020.
Inspire Record 1797444 DOI 10.17182/hepdata.97372

Measurement of Z-boson production in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=8.16$ TeV and Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV is reported. It is performed in the dimuon decay channel, through the detection of muons with pseudorapidity $-4 < \eta_{\mu} < -2.5$ and transverse momentum $p_{\rm T}^{\mu} > 20$ GeV/$c$ in the laboratory frame. The invariant yield and nuclear modification factor are measured for opposite-sign dimuons with invariant mass $60 < m^{\mu\mu} < 120$ GeV$c^2$ and rapidity $2.5 < y_{cms}^{\mu\mu} < 4$. They are presented as a function of rapidity and, for the Pb-Pb collisions, of centrality as well. The results are compared with theoretical calculations, both with and without nuclear modifications to the Parton Distribution Functions (PDFs). In p-Pb collisions the center-of-mass frame is boosted with respect to the laboratory frame, and the measurements cover the backward ($-4.46< y_{cms}^{\mu\mu}<-2.96$) and forward ($2.03< y_{cms}^{\mu\mu}<3.53$) rapidity regions. For the p-Pb collisions, the results are consistent within experimental and theoretical uncertainties with calculations that include both free-nucleon and nuclear-modified PDFs. For the Pb-Pb collisions, a $3.4\sigma$ deviation is seen in the integrated yield between the data and calculations based on the free-nucleon PDFs, while good agreement is found once nuclear modifications are considered.

0 data tables match query

Soft-dielectron excess in proton-proton collisions at $\sqrt{s}$ = 13 TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Phys.Rev.Lett. 127 (2021) 042302, 2021.
Inspire Record 1798514 DOI 10.17182/hepdata.111331

A measurement of dielectron production in proton-proton (pp) collisions at $\sqrt{s} = 13$ TeV, recorded with the ALICE detector at the CERN LHC, is presented in this Letter. The data set was recorded with a reduced magnetic solenoid field. This enables the investigation of a kinematic domain at low dielectron invariant mass $m_{\rm ee}$ and pair transverse momentum $p_{\rm T,ee}$ that was previously inaccessible at the LHC. The cross section for dielectron production is studied as a function of $m_{\rm ee}$, $p_{\rm T,ee}$, and event multiplicity ${\rm d} N_{\rm ch}/{\rm d} \eta$. The expected dielectron rate from hadron decays, called hadronic cocktail, utilizes a parametrization of the measured $\eta/\pi^0$ ratio in pp and proton-nucleus (p-A) collisions, assuming that this ratio shows no strong dependence on collision energy at low transverse momentum. Comparison of the measured dielectron yield to the hadronic cocktail at $0.15<m_{\rm ee}<0.6$ GeV/$c^2$ and for $p_{\rm T,ee} < 0.4$ GeV/$c$ indicates an enhancement of soft dielectrons, reminiscent of the 'anomalous' soft-photon and -dilepton excess in hadron-hadron collisions reported by several experiments under different experimental conditions. The enhancement factor over the hadronic cocktail amounts to $1.61\pm 0.13\,(\rm{stat.})\pm 0.17\,(\rm{syst., data}) \pm 0.34\,(\rm{syst., cocktail})$ in the ALICE acceptance. Acceptance-corrected excess spectra in $m_{\rm ee}$ and $p_{\rm T,ee}$ are extracted and compared with calculations of dielectron production from hadronic bremsstrahlung and thermal radiation within a hadronic many-body approach.

0 data tables match query

Jet-associated deuteron production in pp collisions at $\sqrt{s}=13$ TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Phys.Lett.B 819 (2021) 136440, 2021.
Inspire Record 1829410 DOI 10.17182/hepdata.105975

Deuteron production in high-energy collisions is sensitive to the space-time evolution of the collision system, and is typically described by a coalescence mechanism. For the first time, we present results on jet-associated deuteron production in \pp collisions at $\sqrt{s}=13$ TeV, providing an opportunity to test the established picture for deuteron production in events with a hard scattering. Using a trigger particle with high transverse-momentum ($p_{\rm T}>5$ GeV/$c$) as a proxy for the presence of a jet at midrapidity, we observe a measurable population of deuterons being produced around the jet proxy. The associated deuteron yield measured in a narrow angular range around the trigger particle differs by 2.4-4.8 standard deviations from the uncorrelated background. The data are described by PYTHIA model calculations featuring baryon coalescence.

0 data tables match query

Production of $\omega$ mesons in pp collisions at $\sqrt{s}$ = 7 TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Eur.Phys.J.C 80 (2020) 1130, 2020.
Inspire Record 1805263 DOI 10.17182/hepdata.99031

The invariant differential cross section of inclusive $\omega(782)$ meson production at midrapidity ($|y|<0.5$) in pp collisions at $\sqrt{s}$ = 7 TeV was measured with the ALICE detector at the LHC over a transverse momentum range of 2 < $p_{\rm{T}}$ < 17 GeV/$c$. The $\omega$ meson was reconstructed via its $\omega\rightarrow\pi^+\pi^-\pi^0$ decay channel. The measured $\omega$ production cross section is compared to various calculations: PYTHIA 8.2 Monash 2013 describes the data, while PYTHIA 8.2 Tune 4C overestimates the data by about 50%. A recent NLO calculation, which includes a model describing the fragmentation of the whole vector-meson nonet, describes the data within uncertainties below 6 GeV/$c$, while it overestimates the data by up to 50% for higher $p_{\rm{T}}$. The $\omega/\pi^0$ ratio is in agreement with previous measurements at lower collision energies and the PYTHIA calculations. In addition, the measurement is compatible with transverse mass scaling within the measured $p_{\rm{T}}$ range and the ratio is constant with $C^{\omega/\pi^{0}}$ = 0.67 $\pm$ 0.03 (stat) $\pm$ 0.04 (sys) above a transverse momentum of 2.5 GeV/$c$.

0 data tables match query

Multiplicity and event-scale dependent flow and jet fragmentation in pp collisions at $\sqrt{s}$ = 13 TeV and in p$-$Pb collisions at $\sqrt{s_\mathrm{NN}}$ = 5.02 TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Aglieri Rinella, Gianluca ; et al.
JHEP 03 (2024) 092, 2024.
Inspire Record 2692432 DOI 10.17182/hepdata.151802

Long- and short-range correlations for pairs of charged particles are studied via two-particle angular correlations in pp collisions at $\sqrt{s}=13$ TeV and p$-$Pb collisions at $\sqrt{s_\mathrm{NN}} = 5.02$ TeV. The correlation functions are measured as a function of relative azimuthal angle $\Delta\varphi$ and pseudorapidity separation $\Delta\eta$ for pairs of primary charged particles within the pseudorapidity interval $|\eta| < 0.9$ and the transverse-momentum interval $1 < p_{\rm T} < 4$ GeV/$c$. Flow coefficients are extracted for the long-range correlations ($1.6 < |\Delta\eta| <1.8$) in various high-multiplicity event classes using the low-multiplicity template fit method. The method is used to subtract the enhanced yield of away-side jet fragments in high-multiplicity events. These results show decreasing flow signals toward lower multiplicity events. Furthermore, the flow coefficients for events with hard probes, such as jets or leading particles, do not exhibit any significant changes compared to those obtained from high-multiplicity events without any specific event selection criteria. The results are compared with hydrodynamic-model calculations, and it is found that a better understanding of the initial conditions is necessary to describe the results, particularly for low-multiplicity events.

0 data tables match query

${\rm f}_{0}(980)$ production in inelastic pp collisions at $\sqrt{s} = 5.02$ TeV

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Phys.Lett.B 846 (2023) 137644, 2023.
Inspire Record 2094796 DOI 10.17182/hepdata.136307

The measurement of the production of ${\rm f}_{0}(980)$ in inelastic pp collisions at $\sqrt{s} = 5.02$ TeV is presented. This is the first reported measurement of inclusive ${\rm f}_{0}(980)$ yield at LHC energies. The production is measured at midrapidity, $|y| < 0.5$, in a wide transverse momentum range, $0 < p_{\rm T} < 16$ GeV/$c$, by reconstructing the resonance in the ${\rm f}_{0}(980) \rightarrow \pi^{+}\pi^{-}$ hadronic decay channel using the ALICE detector. The $p_{\rm T}$-differential yields are compared to those of pions, protons and $\phi$ mesons as well as to predictions from the HERWIG 7.2 QCD-inspired Monte Carlo event generator and calculations from a coalescence model that uses the AMPT model as an input. The ratio of the $p_{\rm T}$-integrated yield of ${\rm f}_{0}(980)$ relative to pions is compared to measurements in ${\rm e}^{+}{\rm e}^{-}$ and pp collisions at lower energies and predictions from statistical hadronisation models and HERWIG 7.2. A mild collision energy dependence of the ${\rm f}_{0}(980)$ to pion production is observed in pp collisions from SPS to LHC energies. All considered models underpredict the $p_{\rm T}$-integrated $2{\rm f}_{0}(980)/(\pi^{+}+\pi^{-})$ ratio. The prediction from the canonical statistical hadronisation model assuming a zero total strangeness content of ${\rm f}_{0}(980)$ is consistent with the data within 1.9$\sigma$ and is the closest to the data. The results provide an essential reference for future measurements of the particle yield and nuclear modification in p$-$Pb and Pb$-$Pb collisions, which have been proposed to be instrumental to probe the elusive nature and quark composition of the ${\rm f}_{0}(980)$ scalar meson.

0 data tables match query

First measurement of the $\Lambda$-$\Xi$ interaction in proton-proton collisions at the LHC

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Phys.Lett.B 844 (2023) 137223, 2023.
Inspire Record 2070418 DOI 10.17182/hepdata.133168

The first experimental information on the strong interaction between $\Lambda$ and $\Xi^-$ strange baryons is presented in this Letter. The correlation function of $\Lambda-\Xi^-$ and $\overline{\Lambda}-\overline{\Xi}^{+}$ pairs produced in high-multiplicity proton-proton (pp) collisions at $\sqrt{s}$ = 13 TeV at the LHC is measured as a function of the relative momentum of the pair. The femtoscopy method is used to calculate the correlation function, which is then compared with theoretical expectations obtained using a meson exchange model, chiral effective field theory, and Lattice QCD calculations close to the physical point. Data support predictions of small scattering parameters while discarding versions with large ones, thus suggesting a weak $\Lambda-\Xi^{-}$ interaction. The limited statistical significance of the data does not yet allow one to constrain the effects of coupled channels like $\Sigma-\Xi$ and N$-\Omega$.

0 data tables match query

Measurement of K$^{*}$(892)$^{\mathrm{\pm}}$ production in inelastic pp collisions at the LHC

The ALICE collaboration Acharya, Shreyasi ; Adamova, Dagmar ; Adler, Alexander ; et al.
Phys.Lett.B 828 (2022) 137013, 2022.
Inspire Record 1863048 DOI 10.17182/hepdata.129148

The first results on K$^{*}$(892)$^{\mathrm{\pm}}$ resonance production in inelastic pp collisions at LHC energies of $\sqrt{s} = 5.02$, 8, and 13 TeV are presented. The K$^{*}$(892)$^{\mathrm{\pm}}$ has been reconstructed via its hadronic decay channel K$^{*}$(892)$^{\mathrm{\pm}}$$\rightarrow$$\mathrm {K^0_S}$$~+~\pi^{\pm}$ with the ALICE detector. Measurements of transverse momentum distributions, $p_{\mathrm{T}}$-integrated yields, and mean transverse momenta for charged K$^{*}$(892) are found to be consistent with previous ALICE measurements for neutral K$^{*}$(892) within uncertainties. For $p_{\mathrm{T}} > 1$ GeV/$c$ the K$^{*}$(892)$^{\mathrm{\pm}}$ transverse momentum spectra become harder with increasing centre-of-mass energy from 5.02 to 13 TeV, similar to what previously observed for charged kaons and pions. For $p_{\mathrm{T}} < 1$ GeV/$c$ the K$^{*}$(892)$^{\mathrm{\pm}}$ yield does not evolve significantly and the abundance of K$^{*}$(892)$^{\mathrm{\pm}}$ relative to K is rather independent of the collision energy. The transverse momentum spectra, measured for K$^{*}$(892)$^{\mathrm{\pm}}$ at midrapidity in the interval $0 < p_{\mathrm{T}} < 15$ GeV/$c$, are not well described by predictions of different versions of PYTHIA 6, PYTHIA 8 and EPOS-LHC event generators. These generators reproduce the measured $p_{\mathrm{T}}$-integrated K$^{*\mathrm{\pm}}$/K ratios and describe well the momentum dependence for $p_{\mathrm{T}} < 2$ GeV/$c$.

0 data tables match query