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DOE OSTI2023

Measurement of the Λ hyperon lifetime

A new, more precise measurement of the Λ hyperon lifetime is performed using a large data sample of Pb-Pb collisions at $\sqrt{s_{NN}}$=5.02 TeV with ALICE. The Λ and $\bar{Λ}$ hyperons are reconstructed at midrapidity using their two-body weak decay channel Λ→p+π - and $\bar{Λ}$→$\bar{p}$+π + . The measured value of the Λ lifetime is τ Λ =[261.07±0.37(stat.)±0.72(syst.)] ps. The relative difference between the lifetime of Λ and $\bar{Λ}$, which represents an important test of CPT invariance in the strangeness sector, is also measured. The obtained value (τ Λ -τ $\bar{Λ}$ )/τ Λ =0.0013±0.0028(stat.)±0.0021(syst.) is consistent with zero within the uncertainties. Both measurements of the Λ hyperon lifetime and of the relative difference between τ Λ and τ $\bar{Λ}$ are in agreement with the corresponding world averages of the Particle Data Group and about a factor of three more precise.

43 PARTICLE ACCELERATORS↗

DOE OSTI2023

Pseudorapidity densities of charged particles with transverse momentum thresholds in pp collisions at $\sqrt{s} = 5.02$ and 13 TeV

The pseudorapidity density of charged particles with minimum transverse momentum (p T ) thresholds of 0.15, 0.5, 1, and 2 GeV/c is measured in pp collisions at the center of mass energies of $\sqrt{s}$ = 5.02 and 13 TeV with the ALICE detector. The study is carried out for inelastic collisions with at least one primary charged particle having a pseudorapidity (η) within ± 0.8 and p T larger than the corresponding threshold. In addition, measurements without p T - thresholds are performed for inelastic and nonsingle-diffractive events as well as for inelastic events with at least one charged particle having |η| < 1 in pp collisions at $\sqrt{s}$ = 5.02 TeV for the first time at the LHC. These measurements are compared to the pythia 6, pythia 8, and epos-lhc models. In general, the models describe the η dependence of particle production well. However, discrepancies are observed for the highest transverse momentum threshold (p T > 2 GeV/c), highlighting the importance of such measurements for tuning event generators. The new measurements agree within uncertainties with results from the ATLAS and CMS experiments obtained at $\sqrt{s}$ =13 TeV .

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2023

Exclusive and dissociative $J/ψ$ photoproduction, and exclusive dimuon production, in p-Pb collisions at $\sqrt{s_{NN}}$ = 8.16 $\mathrm{TeV}$

The ALICE Collaboration reports three measurements in ultraperipheral proton-lead collisions at forward rapidity. The exclusive two-photon process γγ → μ + μ - and the exclusive photoproduction of J/ψ are studied. J/ψ photoproduction with proton dissociation is measured for the first time at a hadron collider. The cross section for the two-photon process of dimuons in the invariant mass range from 1 to 2.5 GeV/c 2 agrees with leading-order quantum electrodynamics calculations. The exclusive and dissociative cross sections for J/ψ photoproductions are measured for photon-proton center-of-mass energies from 27 to 57 GeV. They are in good agreement with HERA results.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2024

Measurement of the fraction of jet longitudinal momentum carried by Λ c + baryons in p p collisions

Recent measurements of charm-baryon production in hadronic collisions have questioned the universality of charm-quark fragmentation across different collision systems. In this work the fragmentation of charm quarks into charm baryons is probed, by presenting the first measurement of the longitudinal jet momentum fraction carried by Λ c + baryons, z ∥ ch , in hadronic collisions. The results are obtained in proton-proton ( p p ) collisions at s = 13 TeV at the LHC, with Λ c + baryons and charged (track-based) jets reconstructed in the transverse momentum intervals of 3 ≤ p T Λ c + < 15 GeV / c and 7 ≤ p T jet ch < 15 GeV / c , respectively. The z ∥ ch distribution is compared to a measurement of D 0 -tagged charged jets in p p collisions as well as to 8 simulations. The data hints that the fragmentation of charm quarks into charm baryons is softer with respect to charm mesons, in the measured kinematic interval, as predicted by hadronization models which include color correlations beyond leading-color in the string formation. © 2024 CERN, for the ALICE Collaboration 2024 CERN

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2024

Bottomonium suppression in 5.02 and 8.16 TeV 𝑝-Pb collisions

Here, we compute the suppression of ϒ⁡(1⁢𝑆), ϒ⁡(2⁢𝑆), and ϒ⁡(3⁢𝑆) states in 𝑝-Pb collisions relative to 𝑝⁢𝑝 collisions, including nuclear parton distribution function (nPDF) effects, coherent energy loss, momentum broadening, and final-state interactions in the quark-gluon plasma. We employ the EPPS21 nPDFs and calculate the uncertainty resulting from variation over the associated error sets. To compute coherent energy loss and momentum broadening, we follow the approach of Arleo, Peigne, and collaborators. The 3+1⁢D viscous hydrodynamical background evolution of the quark-gluon plasma is generated by anisotropic hydrodynamics. The in-medium suppression of bottomonium in the quark-gluon plasma is computed using a next-to-leading-order open quantum system framework formulated within potential nonrelativistic quantum chromodynamics. We find that inclusion of all these effects provides a reasonable description of experimental data from the ALICE, ATLAS, CMS, and LHCb Collaborations for the suppression of ϒ⁡(1⁢𝑆), ϒ⁡(2⁢𝑆), and ϒ⁡(3⁢𝑆) as a function of both transverse momentum and rapidity.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2024

Measurement of Ω c 0 baryon production and branching-fraction ratio BR ( Ω c 0 → Ω - e + ν e ) / BR ( Ω c 0 → Ω - π + ) in p p collisions at s = 13 TeV

The inclusive production of the charm-strange baryon $Ω^0_c$ is measured for the first time via its semileptonic decay into $Ω$ - e + ν e at midrapidity (|y| < 0.8) in proton-proton (pp) collisions at the center-of mass energy $\sqrt{s}$ = 13 TeV with the ALICE detector at the LHC. The transverse momentum (p T ) differential cross section multiplied by the branching ratio is presented in the interval 2 < p T < 12 GeV=c. The branching-fraction ratio BR($Ω^0_c$ → $Ω$ - e + ν e )/BR($Ω^0_c$→ Ω - π + ) is measured to be 1.12 ± 0.22 (stat) ± 0.27 (syst). Comparisons with other experimental measurements, as well as with theoretical calculations, are presented

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2025

First measurement of 𝐷 𝑠⁢1 ⁡(1 + )⁢(2536) + and 𝐷$^{*}_{𝑠⁢2}$⁡(2 + )⁢(2573) + production in proton-proton collisions at $\sqrt{s}$ = 13 TeV at the LHC

The production yields of the orbitally excited charm-strange mesons D s⁢1 ⁡(1 + )⁢(2536)+ and 𝐷$^{*}_{𝑠⁢2}$⁡(2 + )⁢(2573) + were measured for the first time in proton-proton (pp) collisions at a center-of-mass energy of $\sqrt{s}$ =13 TeV with the ALICE experiment at the LHC. The D$^{+}_{s⁢1}$ and D$^{*+}_{s⁢2}$ mesons were measured at midrapidity (|𝑦| < 0.5) in minimum-bias and high-multiplicity pp collisions in the transverse-momentum interval 2< 𝑝 T < 24 GeV/𝑐. Their production yields relative to the D$^{+}_{s}$ ground-state yield were found to be compatible between minimum-bias and high-multiplicity collisions, as well as with previous measurements in e ± ⁢p and e + ⁢e − collisions. The measured D$^{+}_{s⁢1}$/D$^{+}_{s}$ and D$^{*+}_{s⁢2}$/D$^{+}_{s}$ yield ratios are described by statistical hadronization models and can be used to tune the parameters governing the production of excited charm-strange hadrons in Monte Carlo generators, such as pythia 8.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2022

Collectivity in Ultraperipheral Pb+Pb Collisions at the Large Hadron Collider

In this work, we present the first full (3+1)D dynamical simulations of ultraperipheral Pb+Pb collisions at the Large Hadron Collider. Extrapolating from p + Pb collisions, we explore whether a quasireal photon γ* interacting with the lead nucleus in an ultraperipheral collision can create a many-body system exhibiting fluid behavior. Assuming strong final-state interactions, we provide model results for charged hadron multiplicity, identified particle mean transverse momenta, and charged hadron anisotropic flow coefficients, and compare them with experimental data from the ALICE and ATLAS Collaborations. The elliptic flow hierarchy between p + Pb and γ*+Pb collisions is dominated by the difference in longitudinal flow decorrelations and reproduces the experimental data well. We have demonstrated that our theoretical framework provides a quantitative tool to study particle production and collectivity for all system sizes, ranging from central heavy-ion collisions to small asymmetric collision systems at the Relativistic Heavy-Ion Collider and the Large Hadron Collider and even at the future Electron-Ion Collider.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2023

First Measurement of Antideuteron Number Fluctuations at Energies Available at the Large Hadron Collider

The first measurement of event-by-event antideuteron number fluctuations in high energy heavy-ion collisions is presented. The measurements are carried out at midrapidity (|η|<0.8) as a function of collision centrality in Pb-Pb collisions at $\sqrt{^sNN}$=5.02 TeV using the ALICE detector. A significant negative correlation between the produced antiprotons and antideuterons is observed in all collision centralities. The results are compared with a state-of-the-art coalescence calculation. While it describes the ratio of higher order cumulants of the antideuteron multiplicity distribution, it fails to describe quantitatively the magnitude of the correlation between antiproton and antideuteron production. On the other hand, thermal-statistical model calculations describe all the measured observables within uncertainties only for correlation volumes that are different with respect to those describing proton yields and a similar measurement of net-proton number fluctuations.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Measurement of the Lifetime and Λ Separation Energy of H Λ 3

The most precise measurements to date of the $^{3}_{Λ}$H lifetime τ and Λ separation energy B Λ are obtained using the data sample of Pb–Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV collected by ALICE at the LHC. The $^{3}_{Λ}$H is reconstructed via its charged two-body mesonic decay channel ($^{3}_{Λ}$H → 3 He + π – and the charge-conjugate process). The measured values τ = [253 ± 11 (stat.) ± 6(syst.)] ps and B Λ = [102 ± 63 (stat.) ± 67 (syst.)] keV are compatible with predictions from effective field theories and confirm that the $^{3}_{Λ}$H structure is consistent with a weakly-bound system.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2024

First Measurement of the |𝑡| Dependence of Incoherent 𝐽/𝜓 Photonuclear Production

The first measurement of the cross section for incoherent photonuclear production of J/ψ vector mesons as a function of the Mandelstam |t| variable is presented. The measurement was carried out with the ALICE detector at midrapidity, |y|<0.8, using ultraperipheral collisions of Pb nuclei at a center-of-mass energy per nucleon pair of $\sqrt{s_{NN}}$ = 5.02 TeV. This rapidity interval corresponds to a Bjorken-x range (0.3–1.4)×10 -3 . Cross sections are given in five |t| intervals in the range 0.04 < |t |< 1 GeV 2 and compared to the predictions by different models. Models that ignore quantum fluctuations of the gluon density in the colliding hadron predict a |t| dependence of the cross section much steeper than in data. The inclusion of such fluctuations in the same models provides a better description of the data.

43 PARTICLE ACCELERATORS↗

DOE OSTI2024

Emergence of Long-Range Angular Correlations in Low-Multiplicity Proton-Proton Collisions

This Letter presents the measurement of near-side associated per-trigger yields, denoted ridge yields, from the analysis of angular correlations of charged hadrons in proton-proton collisions at s = 13 TeV . Long-range ridge yields are extracted for pairs of charged particles with a pseudorapidity difference of 1.4 < | Δ η | < 1.8 and a transverse momentum of 1 < p T < 2 GeV / c , as a function of the charged-particle multiplicity measured at midrapidity. This Letter extends the measurements of the ridge yield to the low multiplicity region, where in hadronic collisions it is typically conjectured that a strongly interacting medium is unlikely to be formed. The precision of the new low multiplicity results allows for the first direct quantitative comparison with the results obtained in e + e − collisions at s = 91 GeV and s = 183 – 209 GeV , where initial-state effects such as preequilibrium dynamics and collision geometry are not expected to play a role. In the multiplicity range 8 ≲ ⟨ N ch ⟩ ≲ 24 where the e + e − results have good precision, the measured ridge yields in p p collisions are substantially larger than the limits set in e + e − annihilations. Consequently, the findings presented in this Letter suggest that the processes involved in e + e − annihilations do not contribute significantly to the emergence of long-range correlations in p p collisions. © 2024 CERN, for the ALICE Collaboration 2024 CERN

43 PARTICLE ACCELERATORS↗

DOE OSTI2024

Observation of Medium-Induced Yield Enhancement and Acoplanarity Broadening of Low-𝑝T Jets from Measurements in 𝑝⁢𝑝 and Central Pb-Pb Collisions at $\sqrt{s_{NN}}$ = 5.02 TeV

The ALICE Collaboration reports the measurement of semi-inclusive distributions of charged-particle jets recoiling from a high transverse momentum (high p T ) hadron trigger in proton-proton and central Pb-Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV. A data-driven statistical method is used to mitigate the large uncorrelated background in central Pb-Pb collisions. Recoil jet distributions are reported for jet resolution parameter R = 0.2, 0.4, and 0.5 in the range 7 < p T.jet < 140 GeV=c and trigger-recoil jet azimuthal separation π/2 < Δφ < π. The measurements exhibit a marked medium-induced jet yield enhancement at low p T and at large azimuthal deviation from Δφ ~ π. The enhancement is characterized by its dependence on Δφ, which has a slope that differs from zero by 4.7σ. Comparisons to model calculations incorporating different formulations of jet quenching are reported. These comparisons indicate that the observed yield enhancement arises from the response of the QGP medium to jet propagation.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2025

Probing Strangeness Hadronization with Event-by-Event Production of Multistrange Hadrons

This Letter presents the first measurement of event-by-event fluctuations of the net number (difference between the particle and antiparticle multiplicities) of multistrange hadrons Ξ − and $\overline{Ξ}$ + and its correlation with the net-kaon number using the data collected by the ALICE Collaboration in pp, p-Pb, and Pb-Pb collisions at a center-of-mass energy per nucleon pair $\sqrt{s_{NN}}$ = 5.02 TeV. The statistical hadronization model with a correlation over three units of rapidity between hadrons having the same and opposite strangeness content successfully describes the results. On the other hand, string-fragmentation models that mainly correlate strange hadrons with opposite strange quark content over a small rapidity range fail to describe the data.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2025

Search for Quasiparticle Scattering in the Quark-Gluon Plasma with Jet Splittings in 𝑝⁢𝑝 and Pb-Pb Collisions at $\sqrt{s_{NN}}$ = 5.02 TeV

The ALICE Collaboration reports measurements of the large relative transverse momentum (𝑘 𝑇 ) component of jet substructure in 𝑝⁢𝑝 and Pb-Pb collisions at center-of-mass energy per nucleon pair $\sqrt{s_{NN}}$ = 5.02 TeV. Enhancement in the yield of such large-𝑘 T emissions in head-on Pb-Pb collisions is predicted to arise from partonic scattering with quasiparticles of the quark-gluon plasma. The analysis utilizes charged-particle jets reconstructed by the anti-𝑘 T algorithm with resolution parameter 𝑅 = 0.2 in the transverse-momentum interval 60 < 𝑝 T,ch,jet < 80 GeV/𝑐. The soft drop and dynamical grooming algorithms are used to identify high transverse momentum splittings in the jet shower. Comparison of measurements in Pb-Pb and 𝑝⁢𝑝 collisions shows medium-induced narrowing, corresponding to yield suppression of high-𝑘 𝑇 splittings, in contrast to the expectation of yield enhancement due to quasiparticle scattering. The measurements are compared to theoretical model calculations incorporating jet modification due to jet-medium interactions (“jet quenching”), both with and without quasiparticle scattering effects. These measurements provide new insight into the underlying mechanisms and theoretical modeling of jet quenching.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2024

Exploring the Strong Interaction of Three-Body Systems at the LHC

Deuterons are atomic nuclei composed of a neutron and a proton held together by the strong interaction. Unbound ensembles composed of a deuteron and a third nucleon have been investigated in the past using scattering experiments, and they constitute a fundamental reference in nuclear physics to constrain nuclear interactions and the properties of nuclei. In this work, K + -d and p-d femtoscopic correlations measured by the ALICE Collaboration in proton-proton (pp) collisions at $\sqrt{s}$ = 13 TeV at the Large Hadron Collider (LHC) are presented. It is demonstrated that correlations in momentum space between deuterons and kaons or protons allow us to study three-hadron systems at distances comparable with the proton radius. The analysis of the K + -d correlation shows that the relative distances at which deuterons and protons or kaons are produced are around 2 fm. The analysis of the p-d correlation shows that only a full three-body calculation that accounts for the internal structure of the deuteron can explain the data. In particular, the sensitivity of the observable to the short-range part of the interaction is demonstrated. These results indicate that correlations involving light nuclei in pp collisions at the LHC will also provide access to any three-body system in the strange and charm sectors.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2023

Time-Energy Uncertainty Relation for Noisy Quantum Metrology

Detection of very weak forces and precise measurement of time are two of the many applications of quantum metrology to science and technology. To sense an unknown physical parameter, one prepares an initial state of a probe system, allows the probe to evolve as governed by a Hamiltonian 𝐻 for some time 𝑡, and then measures the probe. If 𝐻 is known, we can estimate 𝑡 by this method; if 𝑡 is known, we can estimate classical parameters on which 𝐻 depends. The accuracy of a quantum sensor can be limited by either intrinsic quantum noise or by noise arising from the interactions of the probe with its environment. In this work, we introduce and study a fundamental trade-off, which relates the amount by which noise reduces the accuracy of a quantum clock to the amount of information about the energy of the clock that leaks to the environment. Specifically, we consider an idealized scenario in which a party Alice prepares an initial pure state of the clock, allows the clock to evolve for a time that is not precisely known, and then transmits the clock through a noisy channel to a party Bob. Meanwhile, the environment (Eve) receives any information about the clock that is lost during transmission. We prove that Bob’s loss of quantum Fisher information about the elapsed time is equal to Eve’s gain of quantum Fisher information about a complementary energy parameter. We also prove a similar, but more general, trade-off that applies when Bob and Eve wish to estimate the values of parameters associated with two noncommuting observables. We derive the necessary and sufficient conditions for the accuracy of the clock to be unaffected by the noise, which form a subset of the Knill-Laflamme error-correction conditions. A state and its local time-evolution direction, if they satisfy these conditions, are said to form a metrological code. We provide a scheme to construct metrological codes in the stabilizer formalism. We show that there are metrological codes that cannot be written as a quantum error-correcting code with similar distance in which the Hamiltonian acts as a logical operator, potentially offering new schemes for constructing states that do not lose any sensitivity upon application of a noisy channel. We discuss applications of the trade-off relation to sensing using a quantum many-body probe subject to erasure or amplitude-damping noise.

metrology↗

DOE OSTI2025

Indications for Freeze-Out of Charge Fluctuations in the Quark-Gluon Plasma at the LHC

The D-measure of net-charge fluctuations quantifies the variance of net charge in strongly interacting matter. It was introduced over 20 years ago as a potential signal of quark-gluon plasma (QGP) in heavy-ion collisions, where it is expected to be suppressed due to the fractional electric charges of quarks. Measurements have been performed at RHIC and LHC, but the conclusion has been elusive in the absence of quantitative calculations for both scenarios. We address this issue by employing a recently developed formalism of density correlations and incorporate resonance decays, local charge conservation, and experimental kinematic cuts. We find that the hadron gas scenario is in fair agreement with the ALICE data for $\sqrt{{𝑠}_{\textrm{NN}}}$ = 2.76 TeV Pb–Pb collisions only when a very short rapidity range of local charge conservation is enforced, while the QGP scenario is in excellent agreement with experimental data and largely insensitive to the range of local charge conservation. A Bayesian analysis of the data utilizing different priors yields moderate evidence for the freeze-out of charge fluctuations in the QGP phase relative to hadron gas. The upcoming high-fidelity measurements from LHC Run 2 will serve as a precision test of the two scenarios.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗