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A<sc>bstract</sc> Measurements of charged-particle production in pp, p–Pb, and Pb–Pb collisions in the toward, away, and transverse regions with the ALICE detector are discussed. These regions are defined event-by-event relative to the azimuthal direction of the charged trigger particle, which is the reconstructed particle with the largest transverse momentum$$ \left({p}_{\textrm{T}}^{\textrm{trig}}\right) $$ in the range 8<$$ {p}_{\textrm{T}}^{\textrm{trig}} $$ <15 GeV/c. The toward and away regions contain the primary and recoil jets, respectively; both regions are accompanied by the underlying event (UE). In contrast, the transverse region perpendicular to the direction of the trigger particle is dominated by the so-called UE dynamics, and includes also contributions from initial- and final-state radiation. The relative transverse activity classifier,$$ {R}_{\textrm{T}}={N}_{\textrm{ch}}^{\textrm{T}}/\left\langle {N}_{\textrm{ch}}^{\textrm{T}}\right\rangle $$ , is used to group events according to their UE activity, where$$ {N}_{\textrm{ch}}^{\textrm{T}} $$ is the charged-particle multiplicity per event in the transverse region and$$ \left\langle {N}_{\textrm{ch}}^{\textrm{T}}\right\rangle $$ is the mean value over the whole analysed sample. The energy dependence of theRTdistributions in pp collisions at$$ \sqrt{s} $$ = 2.76, 5.02, 7, and 13 TeV is reported, exploring the Koba-Nielsen-Olesen (KNO) scaling properties of the multiplicity distributions. The first measurements of charged-particlepTspectra as a function ofRTin the three azimuthal regions in pp, p–Pb, and Pb–Pb collisions at$$ \sqrt{s_{\textrm{NN}}} $$ = 5.02 TeV are also reported. Data are compared with predictions obtained from the event generators PYTHIA 8 and EPOS LHC. This set of measurements is expected to contribute to the understanding of the origin of collective-like effects in small collision systems (pp and p–Pb).
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Probing the chiral magnetic wave with charge-dependent flow measurements in Pb-Pb collisions at the LHC
A<sc>bstract</sc> 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$$ \sqrt{s_{\textrm{NN}}} $$ = 5.02 TeV to probe the CMW. In particular, the slope of the normalized difference in elliptic (v2) and triangular (v3) 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$$ {r}_3^{\textrm{Norm}} $$ is found to be larger than zero and to have a magnitude similar to$$ {r}_2^{\textrm{Norm}} $$ , thus pointing to a large background contribution for these measurements. Furthermore,$$ {r}_2^{\textrm{Norm}} $$ 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 (fCMW) contribution to this measurement which is compatible with zero. This measurement provides the very first upper limit forfCMW, and in the 10–60% centrality interval it is found to be 26% (38%) at 95% (99.7%) confidence level.
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- PAR ID:
- 10514582
- Author(s) / Creator(s):
- ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
- Publisher / Repository:
- link.springer.com
- Date Published:
- Journal Name:
- Journal of High Energy Physics
- Volume:
- 2023
- Issue:
- 12
- ISSN:
- 1029-8479
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1007/JHEP12(2023)067
