Hadron physics

The international collaboration ALICE (“A Large Ion Collider Experiment”), of which the eponymous research group of the IP2I in Lyon is a member, aims to study nuclear matter in a state of extremely high temperature, where the deconfinement of hadrons (including protons and neutrons) into plasma of quarks and gluons takes place.

Matter is made up of atoms, themselves made up of electrons surrounding a nucleus of protons and neutrons, the latter being formed of quarks, linked by gluons. No quark or gluon has ever been observed in isolation: they appear to be permanently bonded together and confined in composite particles. At temperatures 100,000 times higher than those at the centre of the Sun, they deconform to form a plasma, which would have existed a few microseconds after the Big Bang. This plasma is predicted by the fundamental theory of strong interaction, Quantum Chromodynamics (QCD), and its study allows us to understand the ultimate organization of matter subject to strong interaction and the very first moments of the universe.

The LHC collides lead ions to recreate conditions similar to those immediately after the Big Bang and form this quark and gluon plasma. For this infinitely small study, a huge detector has been built at the LHC. It is capable of measuring the particles emitted by the plasma as it expands and cools.

Our group has been involved in this construction and in obtaining major results in this field of physics.

The activities of the ALICE group of the IP2I of Lyon are twofold:

the analysis of data collected in proton-proton, proton-nucleus and nucleus-nucleus collisions at the CERN LHC
participation in the construction and operation of the forward vertex trajectograph, the Muon Forward Tracker

Analysis of data collected in proton-proton, proton-nucleus and nucleus-nucleus collisions at the CERN LHC

The physics analyses of the ALICE experiment carried out in the Lyon groups cover a wide range of subjects, from the light quark sector u, d, s with the study of the forward production of low mass vector mesons $\rho, \omega$ and $\phi$ in the dimuonic decay channel, to the heavy quarks sector c and b, with the study of the production of the quarkonium states of the $J/\psi$ and $\Lambda$ families. This analytical work has already led to a number of remarkable results, notably through the study of collective phenomena characterizing the evolution of the $J/\psi$ and $\Lambda$ mesons, namely the appearance of kinematic correlations between the $J/\psi$ meson and light hadrons in high multiplicity proton-Pb collisions, and the observation of elliptical flow of the $\Upsilon(1S)$ meson compatible with zero in Pb-Pb collisions (behavior different from all the other particles studied).

Participation in the construction and operation of the forward vertex trajectograph, the Muon Forward Tracker

The group is also responsible for the construction and operation of the vertex forward trajectograph, the Muon Forward Tracker (MFT), one of the first applications in high energy physics of CMOS silicon pixel sensor technology. The MFT, which will be integrated into the ALICE detector starting with Run3 of the LHC (2021), is designed to enable precise measurement of the details of the vertex region for forward-produced particles, especially muons, whose different topologies and production processes can be studied.

PERMANENTS:

NON-PERMANENTS:

- DOCTORANTS / DOCTORAL STUDENTS:

- CHERCHEURS NON-PERMANENTS / NON-PERMANENT RESEARCHERS:

BAILUNG Yoshini

663 documents

Shreyasi Acharya, Fernando Torales - Acosta, Dagmar Adamova, Jonatan Adolfsson, Madan Mohan Aggarwal, et al.. $\Upsilon$ suppression at forward rapidity in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV. Physics Letters B, 2019, 790, pp.89-101. ⟨10.1016/j.physletb.2018.11.067⟩. ⟨hal-01801861⟩
Shreyasi Acharya, Dagmar Adamova, Jonatan Adolfsson, Madan Mohan Aggarwal, Gianluca Aglieri Rinella, et al.. Relative particle yield fluctuations in $\text{ Pb-Pb }$ collisions at $\sqrt{s_\mathrm{{NN}}} =2.76\hbox { TeV}$ . Eur.Phys.J.C, 2019, 79 (3), pp.236. ⟨10.1140/epjc/s10052-019-6711-x⟩. ⟨hal-02073962⟩
Shreyasi Acharya, Fernando Torales - Acosta, Dagmar Adamova, Souvik Priyam Adhya, Alexander Adler, et al.. Calibration of the photon spectrometer PHOS of the ALICE experiment. Journal of Instrumentation, 2019, 14 (05), pp.P05025. ⟨10.1088/1748-0221/14/05/P05025⟩. ⟨hal-02058538⟩
Shreyasi Acharya, Fernando Torales - Acosta, Dagmar Adamova, Souvik Priyam Adhya, Alexander Adler, et al.. $\Lambda_\mathrm{c}^+$ production in Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV. Physics Letters B, 2019, 793, pp.212-223. ⟨10.1016/j.physletb.2019.04.046⟩. ⟨hal-01897170⟩
Shreyasi Acharya, Fernando Torales - Acosta, Dagmar Adamova, Jonatan Adolfsson, Madan Mohan Aggarwal, et al.. Centrality and pseudorapidity dependence of the charged-particle multiplicity density in Xe–Xe collisions at $\sqrt{s_{\rm NN}}$ =5.44TeV. Physics Letters B, 2019, 790, pp.35-48. ⟨10.1016/j.physletb.2018.12.048⟩. ⟨hal-01801857⟩
A. Adare, S. Afanasiev, C. Aidala, N.N. Ajitanand, Y. Akiba, et al.. Beam Energy and Centrality Dependence of Direct-Photon Emission from Ultrarelativistic Heavy-Ion Collisions. Physical Review Letters, 2019, 123 (2), pp.022301. ⟨10.1103/PhysRevLett.123.022301⟩. ⟨hal-01801846⟩
Shreyasi Acharya, Fernando Torales - Acosta, Dagmar Adamova, Jonatan Adolfsson, Madan Mohan Aggarwal, et al.. Direct photon production at low transverse momentum in proton-proton collisions at $\mathbf{\sqrt{s}=2.76}$ and 8 TeV. Physical Review C, 2019, 99 (2), pp.024912. ⟨10.1103/PhysRevC.99.024912⟩. ⟨hal-01768126⟩
Shreyasi Acharya, Dagmar Adamova, Souvik Priyam Adhya, Alexander Adler, Jonatan Adolfsson, et al.. Investigations of Anisotropic Flow Using Multiparticle Azimuthal Correlations in pp, p-Pb, Xe-Xe, and Pb-Pb Collisions at the LHC. Physical Review Letters, 2019, 123 (14), pp.142301. ⟨10.1103/PhysRevLett.123.142301⟩. ⟨hal-02073498⟩
R. Arnaldi, K. Banicz, K. Borer, J. Castor, B. Chaurand, et al.. Nuclear dependence of light neutral meson production in p-A collisions at 400 GeV with NA60. European Physical Journal C: Particles and Fields, 2019, 79 (5), pp.443. ⟨10.1140/epjc/s10052-019-6848-7⟩. ⟨hal-02154290⟩
Shreyasi Acharya, Dagmar Adamova, Souvik Priyam Adhya, Alexander Adler, Jonatan Adolfsson, et al.. Measurement of charged jet cross section in $pp$ collisions at ${\sqrt{s}=5.02}$ TeV. Physical Review D, 2019, 100 (9), pp.092004. ⟨10.1103/PhysRevD.100.092004⟩. ⟨hal-02144198⟩