Présidents de session
Track6-SmallSyst
- Alice Ohlson (Lund University)
Track6-SmallSyst
- Maxime Guilbaud (SUBATECH)
- Maxime Guilbaud (SUBATECH)
We investigate the possibility of a partonic phase in small systems by measuring the elliptic flow of mesons (π⁺⁻, K⁺⁻, K⁰) and baryons (p+$\bar{\rm p}$, Λ+Λ̅) in high-multiplicity p--Pb collisions at $\sqrt{s_{{\rm NN}}}$ = 5.02 TeV and pp collisions at $\sqrt{s}$ = 13 TeV measured by ALICE. The results show a grouping (with 1$\sigma$ significance) and splitting (with 5$\sigma$ confidence)...
This talk presents the latest ATLAS measurements of collective phenomena in small collision systems, including pp collisions and Ultraperipheral collisions (UPC) of heavy ions. In pp collisions, presented measurements include flow decorrelations in rapidity for probing the longitudinal structure and study of the sensitivity of collective motion in pp collisions to the presence of jets, which...
Strangeness enhancement has long been considered a signature of the quark-gluon plasma formation in heavy-ion collisions. Strangeness enhancement has also been observed in small systems at the LHC, but the underlying physics is not yet fully understood. This motivates studies of strange hadron production in small systems at RHIC, where the energy density of system is expected to be smaller...
The creation of a quark-gluon plasma (QGP) is expected in ultrarelativistic heavy ion collisions. It came as a surprise that proton-proton collisions at ultrarelativistic energies show as well a "QGP-like" behavior and signs of the creation of a nearly perfect fluid, although the corresponding system size is not more than a few cubic femtometers. Even more surprisingly, also heavy flavor...
Approaching zero temperature, a gas of strongly-interacting fermions undergoes a transition to a superfluid phase amenable to an ideal hydrodynamic description. At trillion-kelvin temperatures, hadronic matter melts into a quark-gluon plasma (QGP) that flows similarly as a near-perfect fluid. Collider experiments indicate that the signals of QGP formation are mysteriously persistent, emerging...
We present measurements of two-particle angular correlations of charged particles emitted in high-energy $e^{+}e^{-}$ collisions using data collected by the ALEPH detector at LEP between 1992 and 2000. The correlation functions are measured over a wide range of pseudorapidity and azimuthal angle as a function of charged particle multiplicity. Previous measurement with LEP1 data at 91 GeV shows...
I will show thermodynamic entropy calculations based on charged particle multiplicity data from proton-proton collisions measured by ALICE at the LHC in comparison to entanglement entropy calculations based on initial state gluon distributions. The relative agreement of these distributions can be quantified by studying their higher order cumulants. The commonalities between the initial and...
Event classifiers based either on the charged-particle multiplicity or on event topologies, such as spherocity and underlying event activity, have been extensively used in proton-proton (pp) collisions by the ALICE Collaboration at the LHC. These event classifiers became important tools since the observation of fluid-like behavior in high multiplicity pp collisions as for example radial and...
Xenon (Xe) nuclei are deformed and have a nonzero quadrupole moment, whereas lead (Pb) nuclei are considered spherical in shape. The study of XeXe collisions at a center-of-mass energy per nucleon pair of $\sqrt{s_{_{\mathrm{NN}}}} = 5.44$ TeV opens up a window to study nuclear deformation using the CMS experiment. When compared to the Run 3 PbPb data at a center-of-mass energy per nucleon...
This talk presents measurements by the ALICE Collaboration of neutral $\pi^0$, $\eta$, and $\omega$ meson production in proton-proton collisions at $\sqrt{s}$ = 13 TeV. Such measurements can constrain the proton parton distribution functions (PDF) and fragmentation functions (FF), and provide input for background corrections of direct photon and dileption analyses. Measurements of $\pi^0$ and...
