arXiv subjects

Maneesha Pradeep

Publications and source records attributed to Maneesha Pradeep.

6 recordsLinked to original sources

arXiv2026

Tricritical dynamics in $\mathrm{^3He}$-$\mathrm{^4He}$ mixtures and QCD

In this paper we study the universal critical dynamics near the tricritical points in $\mathrm{^3He}$-$\mathrm{^4He}$ mixtures and QCD with two massless quark flavors. In particular, we use the real-time formulation of the functional renormalization group to understand how the tricritical region connects the $O(4)$ Model G dynamics of the two-flavor chiral phase transition to that of Model H for the QCD critical point with explicitly broken chiral symmetry. We show that in presence of an additional subdiffusive energy-like density, the tricritical dynamics inherits the strong dynamic scaling of Model G, where the critical fluctuations of order parameter and conserved $O(N)$ charges relax at identical rates. The strong scaling in the planar $O(2)$ case relevant for the $\lambda$-line and the tricritical point in the liquid $\mathrm{^3He}$-$\mathrm{^4He}$ mixtures arises as an interesting limiting case. Including the explicit symmetry breaking by the finite light-quark masses in QCD, the energy-like density of the tricritical dynamics mixes linearly with the $Z_2$ order parameter to eventually produce the characteristic slow fluctuations of the entropy per baryon near the QCD critical point.

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arXiv2026

Equation of state and cumulants of proton multiplicity in equilibrium near critical point from Pade estimates

The fluctuations of proton multiplicity in heavy-ion collisions are the key observables in the search for the QCD critical point. In this work we present an approach to constraining the cumulants of proton number based on the analytical properties of the QCD equation of state in the vicinity of the critical point. We show that, under the assumption of local equilibrium, the features of the collision energy dependence, such as the peaks and the dips of the cumulants, are significantly constrained by the data on the Lee-Yang singularity structure available via Pade resummation of the lattice QCD data. Furthermore, we identify four topologically distinct scenarios, all within the uncertainty range of the Pade estimates for the non-universal mapping parameters, classified based on the location of the critical point and the slope of the chiral crossover curve with respect to the freeze-out curve. These different scenarios result in qualitatively different critical signatures, especially for the third factorial cumulant and thus could be potentially discriminated using the experimental data.

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arXiv2025

Factorial cumulants of proton multiplicity near a critical point using maximum entropy freeze-out prescription

We present the first application of the maximum-entropy freeze-out prescription to calculate factorial cumulants of proton multiplicities near the conjectured QCD critical point in thermal equilibrium. We map the Gibbs free energy of the 3D Ising model to a parameterized class of possible EoS near QCD critical point. This equilibrium baseline highlights how factorial cumulants isolate critical fluctuations by subtracting trivial self-correlations, setting the stage for future out-of-equilibrium analyses. We identify the key non-universal aspects of the mapping to the Ising model that strongly control the characteristic properties, such as magnitude and location of the peaks of the factorial cumulants along the freeze-out curve.

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arXiv2024

The Hypertriton Puzzle in Relativistic Heavy-Ion Collisions

The yields of hadrons and light nuclei in relativistic collisions of heavy-nuclei at a center of mass energy of 2.6 TeV can be described remarkably well by a thermal distribution of an ideal gas of hadrons and light nuclei interacting only via the decay of resonances. Given the particularly small binding energy of hypertritons relative to the temperature describing the yields (about 156 MeV), one might naturally expect hypertrions to dissociate in medium, making the agreement of hypertriton yields with thermal predictions highly puzzling. The puzzle is compounded by the fact that small binding energy is associated with the large size of the hypertriton. This size is on a similar scale to the overall size of the fireball and much larger than the length scale over which temperatures in the fireball vary over phenomenologically relevant amounts. This paper quantifies the tension this effect causes and shows that it is sufficiently large to render the thermal model inconsistent: its natural assumptions are in conflict with its outputs. The possibility that hypertritons are formed at freeze out as compact objects, quark droplets, that subsequently evolve into hypertritons is considered as a way to resolve the puzzle. It is noted that beyond making the assumption that compact quark droplets form, additional detailed dynamical assumptions which have not been justified are needed to make the thermal model work. The issue of why, despite these issues, the hypertriton is well described by a simple statistical description at freeze out is unresolved. Resolving the hypertriton puzzle is important as it may clarify whether the phenomenological success of the simple thermal model for yields accurately reflects the simple picture of the underlying physics on which it is based.

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arXiv2022

Freezing Out Fluctuations in Hydro+ Near the QCD Critical Point

We introduce a freeze-out procedure to convert the critical fluctuations in a droplet of quark-gluon plasma (QGP) that has, as it expanded and cooled, passed close to a posited critical point on the phase diagram into cumulants of hadron multiplicities that can subsequently be measured. The procedure connects the out-of-equilibrium critical fluctuations described in concert with the hydrodynamic evolution of the droplet of QGP by extended hydrodynamics, known as Hydro+, with the subsequent kinetic description in terms of observable hadrons. We introduce a critical scalar isoscalar field sigma whose fluctuations cause correlations between observed hadrons due to the couplings of the sigma field to the hadrons via their masses. We match the QGP fluctuations obtained by solving the Hydro+ equations describing the evolution of critical fluctuations before freeze-out to the correlations of the sigma field. In turn, these are imprinted onto correlations and fluctuations in the multiplicity of hadrons, most importantly protons, after freeze-out via the generalization of the familiar half-century-old Cooper-Frye freeze-out prescription which we introduce. The proposed framework allows us to study the effects of critical slowing down and the consequent deviation of the observable predictions from equilibrium expectations quantitatively. We also quantify the suppression of cumulants due to conservation of baryon number. We demonstrate the procedure in practice by freezing out a Hydro+ simulation in an azimuthally symmetric and boost invariant background that includes radial flow discussed in arXiv:1908.08539.

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arXiv2021

Freezing out critical fluctuations

We introduce a novel freeze-out procedure connecting the hydrodynamic evolution of a droplet of quark-gluon plasma (QGP) that has, as it expanded and cooled, passed close to a posited critical point on the QCD phase diagram with the subsequent kinetic description in terms of observable hadrons. The procedure converts out-of-equilibrium critical fluctuations described by extended hydrodynamics, known as Hydro+, into cumulants of hadron multiplicities that can be subsequently measured. We introduce a critical sigma field whose fluctuations cause correlations between observed hadrons due to the couplings of the sigma field to the hadrons. We match the QGP fluctuations obtained via solving the Hydro+ equations describing the evolution of critical fluctuations before freeze-out to the correlations of the sigma field. In turn, these are imprinted onto fluctuations in the multiplicities of hadrons, most importantly protons, after freeze-out via a generalization of the familiar half-a-century-old Cooper-Frye freeze-out prescription which we introduce. This framework allows us to study the effects of critical slowing down and the consequent deviation of the observable predictions from equilibrium expectations quantitatively. We can also quantify the suppression of cumulants due to the conservation of baryon number. We demonstrate the prescription in practice by freezing out the Hydro+ simulation in a simplified azimuthally symmetric and boost invariant background discussed in Rajagopal, Ridgway, Weller, Yin, 2019.

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