Thu·Aug 31, 2023Thursday·August 31, 2023

1. 01*

   Lambda polarization at Electron-ion collider in China

   Zhaohuizi Ji🇺🇸 · Xiaoyan Zhao🇨🇳 · Aiqiang Guo🇨🇳 · Qinghua Xu🇨🇳 · Jinlong Zhang🇨🇳

   Lambda polarization can be measured through its self-analyzing weak decay, making it an ideal candidate for studying spin effects in high energy scatterings. In lepton-nucleon deeply inelastic scatterings (DIS), Lambda polarization measurements can probe the polarized parton distribution functions (PDFs) and the polarized fragmentation functions (FFs). One of the most promising facilities for high-energy nuclear physics research is the proposed Electron-ion collider in China (EicC). As a next-generation facility, EicC is set to propel our understandings of nuclear physics to new heights. In this article, we study the Lambda production in electron-proton collision at EicC energy, in particular Lambda's reconstruction based on the performance of the designed EicC detector. In addition, taking spontaneous transverse polarization as an example, we provide a theoretical prediction with statistical projection based on one month of EicC data taking, offering valuable insights into future research prospects.

   nucl-exhep-phNucl.Sci.Tech.(2023)·10 citations
2. 02*

   New proton-capture rates on carbon isotopes and their impact on the astrophysical ${}^{12}\mathrm{C}/{}^{13}\mathrm{C}$ ratio

   J. Skowronski🇮🇹 · A. Boeltzig🇮🇹 · G. F. Ciani🇮🇹 · L. Csedreki · D. Piatti · M. Aliotta🇬🇧 · C. Ananna🇮🇹 · F. Barile · D. Bemmerer🇩🇪 · A. Best🇮🇹 · C. Broggini🇮🇹 · C. G. Bruno🇬🇧 and 34 other authors

   The ${}^{12}\mathrm{C}/{}^{13}\mathrm{C}$ ratio is a significant indicator of nucleosynthesis and mixing processes during hydrogen burning in stars. Its value mainly depends on the relative rates of the ${}^{12}\mathrm{C}(p,\gamma ){}^{13}\mathrm{N}$ and ${}^{13}\mathrm{C}(p,\gamma ){}^{14}\mathrm{N}$ reactions. Both reactions have been studied at the Laboratory for Underground Nuclear Astrophysics (LUNA) in Italy down to the lowest energies to date ($E_{c.m.}=60\mathrm{keV}$) reaching for the first time the high energy tail of hydrogen burning in the shell of giant stars. Our cross sections, obtained with both prompt $\gamma$-ray detection and activation measurements, are the most precise to date with overall systematic uncertainties of $7-8\%$. Compared with most of the literature, our results are systematically lower, by $25\%$ for the ${}^{12}\mathrm{C}(p,\gamma ){}^{13}\mathrm{N}$ reaction and by $30\%$ for ${}^{13}\mathrm{C}(p,\gamma ){}^{14}\mathrm{N}$. We provide the most precise value up to now of $(3.6\pm 0.4)$ in the $20-140\mathrm{MK}$ range for the lowest possible ${}^{12}\mathrm{C}/{}^{13}\mathrm{C}$ ratio that can be produced during H burning in giant stars.

   nucl-exPRL(2023)·15 citations
3. 03*

   System size dependence of the hadronic rescattering effect at energies available at the CERN Large Hadron Collider

   ALICE Collaboration

   The first measurements of ${\mathrm{K}}^{\ast }(892{)}^0$ resonance production as a function of charged-particle multiplicity in Xe$-$Xe collisions at $\sqrt{s_{\mathrm{NN}}}=$ 5.44 TeV and pp collisions at $\sqrt{s}=$ 5.02 TeV using the ALICE detector are presented. The resonance is reconstructed at midrapidity ($|y|<0.5$) using the hadronic decay channel ${\mathrm{K}}^{\ast 0}\to {\mathrm{K}}^{\pm }{\pi }^{\mp }$. Measurements of transverse-momentum integrated yield, mean transverse-momentum, nuclear modification factor of ${\mathrm{K}}^{\ast 0}$, and yield ratios of resonance to stable hadron (${\mathrm{K}}^{\ast 0}$/K) are compared across different collision systems (pp, p$-$Pb, Xe$-$Xe, and Pb$-$Pb) at similar collision energies to investigate how the production of ${\mathrm{K}}^{\ast 0}$ resonances depends on the size of the system formed in these collisions. The hadronic rescattering effect is found to be independent of the size of colliding systems and mainly driven by the produced charged-particle multiplicity, which is a proxy of the volume of produced matter at the chemical freeze-out. In addition, the production yields of ${\mathrm{K}}^{\ast 0}$ in Xe$-$Xe collisions are utilized to constrain the dependence of the kinetic freeze-out temperature on the system size using the hadron resonance gas in partial chemical equilibrium (HRG-PCE) model.

   nucl-exhep-exPRC(2024)·20 citations
4. 04*

   Multiplicity-dependent production of $\Sigma (1385{)}^{\pm }$ and $\Xi (1530{)}^0$ in pp collisions at $\sqrt{s}=13$ TeV

   ALICE Collaboration

   The production yields of the $\Sigma (1385{)}^{\pm }$ and $\Xi (1530{)}^0$ resonances are measured in pp collisions at $\sqrt{s}=13$ TeV with ALICE. The measurements are performed as a function of the charged-particle multiplicity $⟨\mathrm{d}{N}_{\mathrm{ch}}/\mathrm{d}\eta ⟩$, which is related to the energy density produced in the collision. The results include transverse momentum ($p_{\mathrm{T}}$) distributions, $p_{\mathrm{T}}$-integrated yields, mean transverse momenta of $\Sigma (1385{)}^{\pm }$ and $\Xi (1530{)}^0$, as well as ratios of the $p_{\mathrm{T}}$-integrated resonance yields relative to yields of other hadron species. The $\Sigma (1385{)}^{\pm }/{\pi }^{\pm }$ and $\Xi (1530{)}^0/{\pi }^{\pm }$ yield ratios are consistent with the trend of the enhancement of strangeness production from low to high multiplicity pp collisions, which was previously observed for strange and multi-strange baryons. The yield ratio between the measured resonances and the long-lived baryons with the same strangeness content exhibits a hint of a mild increasing trend at low multiplicity, despite too large uncertainties to exclude the flat behaviour. The results are compared with predictions from models such as EPOS-LHC and PYTHIA 8 with Rope shoving. The latter provides the best description of the multiplicity dependence of the $\Sigma (1385{)}^{\pm }$ and $\Xi (1530{)}^0$ production in pp collisions at $\sqrt{s}=13$ TeV.

   nucl-exhep-exJHEP(2024)·15 citations
5. 05*

   K${}^{\ast }$(892)${}^{\pm }$ resonance production in Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV

   ALICE Collaboration

   The production of K${}^{\ast }$(892)${}^{\pm }$ meson resonance is measured at midrapidity ($|y|<0.5$) in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV using the ALICE detector at the LHC. The resonance is reconstructed via its hadronic decay channel K${}^{\ast }$(892)${}^{\pm }\to {\mathrm{K}}_{\mathrm{S}}^0{\pi }^{\pm }$. The transverse momentum distributions are obtained for various centrality intervals in the $p_{\mathrm{T}}$ range of 0.4-16 GeV/$c$. The reported measurements of integrated yields, mean transverse momenta, and particle yield ratios are consistent with previous ALICE measurements for K${}^{\ast }$(892)${}^0$. The $p_{\mathrm{T}}$-integrated yield ratio 2K${}^{\ast }$(892)${}^{\pm }$/(${\mathrm{K}}^{+}+{\mathrm{K}}^{-}$) in central Pb-Pb collisions shows a significant suppression (9.3$\sigma$) relative to pp collisions. Thermal model calculations overpredict the particle yield ratio. Although both simulations consider the hadronic phase, only HRG-PCE accurately represents the measurements, whereas MUSIC+SMASH tends to overpredict them. These observations, along with the kinetic freeze-out temperatures extracted from the yields of light-flavored hadrons using the HRG-PCE model, indicate a finite hadronic phase lifetime, which increases towards central collisions. The $p_{\mathrm{T}}$-differential yield ratios 2K${}^{\ast }$(892)${}^{\pm }$/(${\mathrm{K}}^{+}+{\mathrm{K}}^{-}$) and 2K${}^{\ast }$(892)${}^{\pm }$/(${\pi }^{+}+{\pi }^{-}$) are suppressed by up to a factor of five at $p_{\mathrm{T}}<2$ GeV/$c$ in central Pb-Pb collisions compared to pp collisions at $\sqrt{s}=$ 5.02 TeV. Both particle ratios and are qualitatively consistent with expectations for rescattering effects in the hadronic phase. The nuclear modification factor shows a smooth evolution with centrality and is below unity at $p_{\mathrm{T}}>8$ GeV/$c$, consistent with measurements for other light-flavored hadrons. The smallest values are observed in most central collisions, indicating larger energy loss of partons traversing the dense medium.

   nucl-exhep-exPRC(2024)·24 citations
6. 06*

   Exploring the strong interaction of three-body systems at the LHC

   ALICE Collaboration

   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 systems in the strange and charm sectors.

   nucl-exhep-exPRX(2024)·52 citations
7. 07*

   Probing the Chiral Magnetic Wave with charge-dependent flow measurements in Pb-Pb collisions at the LHC

   ALICE Collaboration

   The Chiral Magnetic Wave (CMW) phenomenon is essential to provide insights into the strong interaction in QCD, the properties of the quark-gluon plasma, and the topological characteristics of the early universe, offering a deeper understanding of fundamental physics in high-energy collisions. Measurements of the charge-dependent anisotropic flow coefficients are studied in Pb-Pb collisions at center-of-mass energy per nucleon-nucleon collision $\sqrt{s_{\mathrm{NN}}}=$ 5.02 TeV to probe the CMW. In particular, the slope of the normalized difference in elliptic ($v_2$) and triangular ($v_3$) flow coefficients of positively and negatively charged particles as a function of their event-wise normalized number difference, is reported for inclusive and identified particles. The slope $r_3^{\mathrm{Norm}}$ is found to be larger than zero and to have a magnitude similar to $r_2^{\mathrm{Norm}}$, thus pointing to a large background contribution for these measurements. Furthermore, $r_2^{\mathrm{Norm}}$ can be described by a blast wave model calculation that incorporates local charge conservation. In addition, using the event shape engineering technique yields a fraction of CMW ($f_{\mathrm{CMW}}$) contribution to this measurement which is compatible with zero. This measurement provides the very first upper limit for $f_{\mathrm{CMW}}$, and in the 10-60% centrality interval it is found to be 26% (38%) at 95% (99.7%) confidence level.

   nucl-exhep-exJHEP(2023)·9 citations
8. 08*

   Prompt and non-prompt J$/\psi$ production at midrapidity in Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV

   ALICE Collaboration

   The transverse momentum ($p_{\mathrm{T}}$) and centrality dependence of the nuclear modification factor $R_{\mathrm{AA}}$ of prompt and non-prompt J$/\psi$, the latter originating from the weak decays of beauty hadrons, have been measured by the ALICE collaboration in Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV. The measurements are carried out through the ${\mathrm{e}}^{+}{\mathrm{e}}^{-}$ decay channel at midrapidity ($|y|<0.9$) in the transverse momentum region $1.5<p_{\mathrm{T}}<10$ GeV/$c$. Both prompt and non-prompt J$/\psi$ measurements indicate a significant suppression for $p_{\mathrm{T}}>$ 5 GeV/$c$, which becomes stronger with increasing collision centrality. The results are consistent with similar LHC measurements in the overlapping $p_{\mathrm{T}}$ intervals, and cover the kinematic region down to $p_{\mathrm{T}}$ = 1.5 GeV/$c$ at midrapidity, not accessible by other LHC experiments. The suppression of prompt J$/\psi$ in central and semicentral collisions exhibits a decreasing trend towards lower transverse momentum, described within uncertainties by models implementing J$/\psi$ production from recombination of c and $\overline{\mathrm{c}}$ quarks produced independently in different partonic scatterings. At high transverse momentum, transport models including quarkonium dissociation are able to describe the suppression for prompt J$/\psi$. For non-prompt J$/\psi$, the suppression predicted by models including both collisional and radiative processes for the computation of the beauty-quark energy loss inside the quark$-$gluon plasma is consistent with measurements within uncertainties.

   nucl-exhep-exJHEP(2024)·31 citations
9. 09*

   Measurements of jet quenching using semi-inclusive hadron+jet distributions in pp and central Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV

   ALICE Collaboration

   The ALICE Collaboration reports measurements of the semi-inclusive distribution of charged-particle jets recoiling from a high transverse momentum (high $p_{\mathrm{T}}$) charged hadron, in pp and central Pb$-$Pb collisions at center-of-mass energy per nucleon$-$nucleon collision $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV. The large uncorrelated background in central Pb$-$Pb collisions is corrected using a data-driven statistical approach, which enables precise measurement of recoil jet distributions over a broad range in $p_{\mathrm{T},\mathrm{ch}\mathrm{jet}}$ and jet resolution parameter $R$. Recoil jet yields are reported for $R=0.2$, 0.4, and 0.5 in the range $7<p_{\mathrm{T},\mathrm{ch}\mathrm{jet}}<140$ GeV$/c$ and $\pi /2<\Delta \phi <\pi$, where $\Delta \phi$ is the azimuthal angular separation between hadron trigger and recoil jet. The low $p_{\mathrm{T},\mathrm{ch}\mathrm{jet}}$ reach of the measurement explores unique phase space for studying jet quenching, the interaction of jets with the quark-gluonnplasma generated in high-energy nuclear collisions. Comparison of $p_{\mathrm{T},\mathrm{ch}\mathrm{jet}}$ distributions from pp and central Pb$-$Pb collisions probes medium-induced jet energy loss and intra-jet broadening, while comparison of their acoplanarity distributions explores in-medium jet scattering and medium response. The measurements are compared to theoretical calculations incorporating jet quenching.

   nucl-exhep-exPRC(2024)·27 citations
10. 10*

    Observation of medium-induced yield enhancement and acoplanarity broadening of low-$p_{\mathrm{T}}$ jets from measurements in pp and central Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV

    ALICE Collaboration

    The ALICE Collaboration reports the measurement of semi-inclusive distributions of charged-particle jets recoiling from a high transverse momentum (high $p_{\mathrm{T}}$) hadron trigger in proton$-$proton and central Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ 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 $7<p_{\mathrm{T},\mathrm{jet}}<140$ GeV$/c$ and trigger$-$recoil jet azimuthal separation $\pi /2<\Delta \phi <\pi$. The measurements exhibit a marked medium-induced jet yield enhancement at low $p_{\mathrm{T}}$ and at large azimuthal deviation from $\Delta \phi \sim \pi$. The enhancement is characterized by its dependence on $\Delta \phi$, which has a slope that differs from zero by 4.7$\sigma$. 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.

    nucl-exhep-exPRL(2024)·32 citations
11. 11*

    Reanalysis of the $\beta -\overline{{\nu }_e}$ Angular Correlation Measurement from the aSPECT Experiment with New Constraints on Fierz Interference

    M. Beck🇩🇪 · W. Heil🇩🇪 · C. Schmidt🇩🇪 · S. Baeßler🇺🇸 · F. Glück🇩🇪 · G. Konrad🇦🇹 · U. Schmidt🇩🇪

    On the basis of revisions of some of the systematic errors, we reanalyzed the electron-antineutrino angular correlation ($a$ coefficient) in free neutron decay inferred from the recoil energy spectrum of the protons which are detected in 4$\pi$ by the aSPECT spectrometer. With $a=-0.10402(82)$ the new value differs only marginally from the one published in 2020. The experiment also has sensitivity to $b$, the Fierz interference term. From a correlated $(b,a)$ fit to the proton recoil spectrum, we derive a limit of $b=-0.0098(193)$ which translates into a somewhat improved 90 \% CL region of $-0.041\le b\le 0.022$ on this hypothetical term. Tighter constraints on $b$ can be set from a combined${}^{(c)}$ analysis of the PERKEO~III ($\beta$ asymmetry) and aSPECT measurement which suggests a finite value of $b$ with $b^{(c)}$ = -0.0181 $\pm$ 0.0065 deviating by 2.82$\sigma$ from the standard model.

    nucl-exPRL(2024)·20 citations
12. 12*

    Skewness and kurtosis of mean transverse momentum fluctuations at the LHC energies

    ALICE Collaboration

    The first measurements of skewness and kurtosis of mean transverse momentum ($⟨p_{\mathrm{T}}⟩$) fluctuations are reported in Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV, Xe$-$Xe collisions at $\sqrt{s_{\mathrm{NN}}}$ $=$ 5.44 TeV and pp collisions at $\sqrt{s}=5.02$ TeV using the ALICE detector. The measurements are carried out as a function of system size $⟨\mathrm{d}{N}_{\mathrm{ch}}/\mathrm{d}\eta {⟩}_{|\eta |<0.5}^{1/3}$, using charged particles with transverse momentum ($p_{\mathrm{T}}$) and pseudorapidity ($\eta$), in the range $0.2<p_{\mathrm{T}}<3.0$ GeV/$c$ and $|\eta |<0.8$, respectively. In Pb$-$Pb and Xe$-$Xe collisions, positive skewness is observed in the fluctuations of $⟨p_{\mathrm{T}}⟩$ for all centralities, which is significantly larger than what would be expected in the scenario of independent particle emission. This positive skewness is considered a crucial consequence of the hydrodynamic evolution of the hot and dense nuclear matter created in heavy-ion collisions. Furthermore, similar observations of positive skewness for minimum bias pp collisions are also reported here. Kurtosis of $⟨p_{\mathrm{T}}⟩$ fluctuations is found to be in good agreement with the kurtosis of Gaussian distribution, for most central Pb$-$Pb collisions. Hydrodynamic model calculations with MUSIC using Monte Carlo Glauber initial conditions are able to explain the measurements of both skewness and kurtosis qualitatively from semicentral to central collisions in Pb--Pb system. Color reconnection mechanism in PYTHIA8 model seems to play a pivotal role in capturing the qualitative behavior of the same measurements in pp collisions.

    nucl-exhep-exPLB(2024)·27 citations
13. 13*

    Excited Hadron Channels in Hadronization

    Rainer J. Fries🇺🇸 · Jacob Purcell🇺🇸 · Michael Kordell II🇺🇸 · Che-Ming Ko🇺🇸

    The proper treatment of hadronic resonances plays an important role in many aspects of heavy ion collisions. This is expected to be the case also for hadronization, due to the large degeneracies of excited states, and the abundant production of hadrons from their decays. We first show how a comprehensive treatment of excited meson states can be incorporated into quark recombination, and in extension, into Hybrid Hadronization. We then discuss the quantum mechanics of forming excited states, utilizing the Wigner distribution functions of angular momentum eigenstates of isotropic 3-D harmonic oscillators. We further describe how resonance decays can be handled, based on a set of minimal assumptions, by creating an extension of hadron decays in PYTHIA 8. Finally, we present first results by simulating $e^{+}{e}^{-}$ collisions using PYTHIA and Hybrid Hadronization with excited mesons up to orbital angular momentum $L=4$ and radial quantum number 2. We find that states up to $L=2$ are produced profusely by quark recombination.

    ↳ nucl-thnucl-exPoS(2024)·1 citation
14. 14*

    Ab initio uncertainty quantification of neutrinoless double-beta decay in ${}^{76}$Ge

    A. Belley🇨🇦 · J. M. Yao🇨🇳 · B. Bally🇫🇷 · J. Pitcher🇨🇦 · J. Engel🇺🇸 · H. Hergert🇺🇸 · J. D. Holt🇨🇦 · T. Miyagi🇩🇪 · T. R. Rodriguez🇪🇸 · A. M. Romero🇪🇸 · S. R. Stroberg🇺🇸 · X. Zhang🇨🇳

    The observation of neutrinoless double-beta ($0\nu \beta \beta$) decay would offer proof of lepton number violation, demonstrating that neutrinos are Majorana particles, while also helping us understand why there is more matter than antimatter in the Universe. If the decay is driven by the exchange of the three known light neutrinos, a discovery would, in addition, link the observed decay rate to the neutrino mass scale through a theoretical quantity known as the nuclear matrix element (NME). Accurate values of the NMEs for all nuclei considered for use in $0\nu \beta \beta$ experiments are therefore crucial for designing and interpreting those experiments. Here, we report the first comprehensive ab initio uncertainty quantification of the $0\nu \beta \beta$-decay NME, in the key nucleus ${}^{76}$Ge. Our method employs nuclear strong and weak interactions derived within chiral effective field theory and recently developed many-body emulators. Our result, with a conservative treatment of uncertainty, is an NME of $2.60_{-1.36}^{+1.28}$, which, together with the best-existing half-life sensitivity and phase-space factor, sets an upper limit for effective neutrino mass of $187_{-62}^{+205}$ meV. The result is important for designing next-generation germanium detectors aiming to cover the entire inverted hierarchy region of neutrino masses.

    ↳ nucl-thhep-exhep-phnucl-exPRL(2024)·87 citations
15. 15*

    Lepton-induced reactions on nuclei in a wide kinematical regime

    U. Mosel🇩🇪 · K. Gallmeister🇩🇪

    Inclusive differential cross sections for various $eA$ and $\nu A$ reactions are analyzed within the GiBUU theoretical framework and code. The treatment of electron-nuclus reactions has been significantly improved by implementing a parametrized description of electron-nucleon interactions for a nucleon. Using the momentum of a nucleon inside the Fermi sea the electron-nucleon cross sections are then Lorentz-boosted to obtain the electron structure functions for nuclei. The neutrino structure functions are obtained from the ones for electrons by a transformation that involves the axial formfactors and kinematical factors that account for the difference of vector and axial currents. Special emphasis is put on analyzing data from various different experiments in different neutrino energy regimes with one and the same theoretical input.

    ↳ nucl-thhep-exhep-phnucl-exPRD(2024)·19 citations
16. 16*

    Search for jet quenching effects in high-multiplicity pp collisions at $\sqrt{s}$ = 13 TeV via di-jet acoplanarity

    ALICE Collaboration

    The ALICE Collaboration reports a search for jet quenching effects in high-multiplicity (HM) proton$-$proton collisions at $\sqrt{s}$ = 13 TeV, using the semi-inclusive azimuthal-difference distribution $\Delta \phi$ of charged-particle jets recoiling from a high transverse momentum (high-$p_{\mathrm{T},\mathrm{trig}}$) trigger hadron. Jet quenching may broaden the $\Delta \phi$ distribution measured in HM events compared to that in minimum bias (MB) events. The measurement employs a $p_{\mathrm{T},\mathrm{trig}}$-differential observable for data-driven suppression of the contribution of multiple partonic interactions, which is the dominant background. While azimuthal broadening is indeed observed in HM compared to MB events, similar broadening for HM events is observed for simulations based on the PYTHIA 8 Monte Carlo generator, which does not incorporate jet quenching. Detailed analysis of these data and simulations show that the azimuthal broadening is due to bias of the HM selection towards events with multiple jets in the final state. The identification of this bias has implications for all jet quenching searches where selection is made on the event activity.

    ↳ hep-exnucl-exJHEP(2024)·32 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.