[Paper Review] Search for a mixed phase of strongly interacting matter at the JINR Nuclotron

A. Sissakian, A. S. Sorin+3 more|ArXiv.org|Nov 8, 2005

High-Energy Particle Collisions Research3 citations

TL;DR

This paper proposes using the JINR Nuclotron accelerator to study the mixed phase of strongly interacting matter at 5 AGeV, leveraging dynamical trajectories in the T–μB phase diagram to probe conditions near the deconfinement and chiral symmetry restoration transition. Key signals include in-medium modifications of ρ- and σ-mesons, HBT correlations, and multiplicity fluctuations, offering a pilot study for future FAIR and NICA experiments.

ABSTRACT

A physical program is formulated for new facilities opening in Dubna for acceleration of heavy ions with an energy up to 5 AGeV.

Motivation & Objective

• To investigate the formation of a mixed phase of strongly interacting matter near the deconfinement and chiral symmetry restoration transition using heavy-ion collisions at the Nuclotron.
• To explore the energy dependence of hadron production properties in the 5 AGeV regime as a precursor to FAIR and NICA experiments.
• To detect signatures of phase transition via in-medium modifications of vector mesons (ρ, ω), spectral functions (σ-meson), and multiparticle correlations.
• To establish a comprehensive experimental program at the Nuclotron to map the phase diagram in the low-to-intermediate energy regime.
• To provide a foundation for future high-precision studies at SIS-100/300 and the NICA collider by testing theoretical models with data.

Proposed method

• Simulate central Au+Au collisions using relativistic 3-fluid hydrodynamics to trace dynamical trajectories in the T–nB and T–μB planes.
• Use the two-phase bag model to estimate phase boundaries for deconfinement and chiral symmetry restoration.
• Model in-medium modifications of ρ-meson spectral functions using the Rapp-Wambach and Brown-Rho scenarios.
• Analyze di-electron invariant mass spectra to detect low-mass lepton pairs from decaying vector mesons as probes of dense matter.
• Apply Hanbury-Brown-Twiss (HBT) correlation techniques to extract space-time characteristics (size, lifetime, freeze-out duration) of the emission source.
• Perform centrality-scanning of observables such as multiplicity, transverse momentum, and flow to detect critical behavior near phase transitions.

Experimental results

Research questions

• RQ1 Can the Nuclotron at 5 AGeV access the mixed phase region of the QCD phase diagram near the deconfinement and chiral symmetry restoration transition?
• RQ2 What signatures of the mixed phase can be observed in the energy dependence of hadron yields, spectral functions, and multiplicity fluctuations?
• RQ3 How do in-medium modifications of ρ- and σ-mesons serve as probes of chiral symmetry restoration in dense nuclear matter?
• RQ4 To what extent can HBT correlations and flow measurements reveal changes in the space-time evolution of the fireball near the phase transition?
• RQ5 How do centrality and beam energy scans at the Nuclotron reveal critical phenomena and equation of state features in strongly interacting matter?

Key findings

• At 5 AGeV, the dynamical trajectory in the T–μB plane reaches the mixed phase region for a short duration, indicating access to critical QCD matter conditions.
• The ρ-meson spectral function is expected to show in-medium broadening and mass shifts, with enhanced low-mass di-lepton yields detectable in electron pair spectra.
• The σ-meson, as the chiral partner of the pion, is predicted to show changes in mass and width that signal chiral symmetry restoration.
• HBT analysis at the Nuclotron can resolve source size, lifetime, and expansion dynamics, with potential signatures of volume expansion if a mixed phase forms.
• Multiplicity and transverse momentum fluctuations across centrality and energy scans may reveal critical behavior near the phase transition point.
• The proposed program at the Nuclotron provides a viable pilot experiment for FAIR and NICA, with measurable signals expected in hadron spectra and correlations.