Paolo Parotto

Bio: Paolo Parotto is an academic researcher from University of Wuppertal. The author has contributed to research in topics: Lattice QCD & Quantum chromodynamics. The author has an hindex of 11, co-authored 47 publications receiving 476 citations. Previous affiliations of Paolo Parotto include University of Houston.

QCD Crossover at Finite Chemical Potential from Lattice Simulations

Abstract: We provide the most accurate results for the QCD transition line so far. We optimize the definition of the crossover temperature ${T}_{c}$, allowing for its very precise determination, and extrapolate from imaginary chemical potential up to real ${\ensuremath{\mu}}_{B}\ensuremath{\approx}300\text{ }\text{ }\mathrm{MeV}$. The definition of ${T}_{c}$ adopted in this work is based on the observation that the chiral susceptibility as a function of the condensate is an almost universal curve at zero and imaginary ${\ensuremath{\mu}}_{B}$. We obtain the parameters ${\ensuremath{\kappa}}_{2}=0.0153(18)$ and ${\ensuremath{\kappa}}_{4}=0.00032(67)$ as a continuum extrapolation based on ${N}_{t}=10$, 12, 16 lattices with physical quark masses. We also extrapolate the peak value of the chiral susceptibility and the width of the chiral transition along the crossover line. In fact, both of these are consistent with a constant function of ${\ensuremath{\mu}}_{B}$. We see no sign of criticality in the explored range.

Constraining the hadronic spectrum through QCD thermodynamics on the lattice

Abstract: Fluctuations of conserved charges allow us to study the chemical composition of hadronic matter. A comparison between lattice simulations and the hadron resonance gas (HRG) model suggested the existence of missing strange resonances. To clarify this issue we calculate the partial pressures of mesons and baryons with different strangeness quantum numbers using lattice simulations in the confined phase of QCD. In order to make this calculation feasible, we perform simulations at imaginary strangeness chemical potentials. We systematically study the effect of different hadronic spectra on thermodynamic observables in the HRG model and compare to lattice QCD results. We show that, for each hadronic sector, the well-established states are not enough in order to have agreement with the lattice results. Additional states, either listed in the Particle Data Group booklet (PDG) but not well established, or predicted by the quark model (QM), are necessary in order to reproduce the lattice data. For mesons, it appears that the PDG and the quark model do not list enough strange mesons, or that, in this sector, interactions beyond those included in the HRG model are needed to reproduce the lattice QCD results.

QCD equation of state matched to lattice data and exhibiting a critical point singularity

Abstract: We construct a family of equations of state for QCD in the temperature range $30\phantom{\rule{0.16em}{0ex}}\mathrm{MeV}\ensuremath{\le}T\ensuremath{\le}800\phantom{\rule{0.16em}{0ex}}\mathrm{MeV}$ and in the chemical potential range $0\ensuremath{\le}{\ensuremath{\mu}}_{B}\ensuremath{\le}450\phantom{\rule{0.16em}{0ex}}\mathrm{MeV}$. These equations of state match available lattice QCD results up to $O({\ensuremath{\mu}}_{B}^{4})$ and in each of them we place a critical point in the three-dimensional (3D) Ising model universality class. The position of this critical point can be chosen in the range of chemical potentials covered by the second Beam Energy Scan at the Relativistic Heavy Ion Collider. We discuss possible choices for the free parameters, which arise from mapping the Ising model onto QCD. Our results for the pressure, entropy density, baryon density, energy density, and speed of sound can be used as inputs in the hydrodynamical simulations of the fireball created in heavy ion collisions. We also show our result for the second cumulant of the baryon number in thermal equilibrium, displaying its divergence at the critical point. In the future, comparisons between RHIC data and the output of the hydrodynamic simulations, including calculations of fluctuation observables, built upon the model equations of state that we have constructed may be used to locate the critical point in the QCD phase diagram, if there is one to be found.

Effect of the QCD equation of state and strange hadronic resonances on multiparticle correlations in heavy ion collisions

Abstract: The QCD equation of state at zero baryon chemical potential is the only element of the standard dynamical framework to describe heavy ion collisions that can be directly determined from first principles. Continuum extrapolated lattice QCD equations of state have been computed using 2+1 quark flavors (up/down and strange) as well as 2+1+1 flavors to investigate the effect of thermalized charm quarks on QCD thermodynamics. Lattice results have also indicated the presence of new strange resonances that not only contribute to the equation of state of QCD matter but also affect hadronic afterburners used to model the later stages of heavy ion collisions. We investigate how these new developments obtained from first principles calculations affect multiparticle correlations in heavy ion collisions. We compare the commonly used equation of state S95n-v1, which was constructed using what are now considered outdated lattice results and hadron states, to the current state-of-the-art lattice QCD equations of state with 2+1 and 2+1+1 flavors coupled to the most up-to-date hadronic resonances and their decays. New hadronic resonances lead to an enhancement in the hadronic spectra at intermediate ${p}_{T}$. Using an outdated equation of state can directly affect the extraction of the shear viscosity to entropy density ratio, $\ensuremath{\eta}/s$, of the quark-gluon plasma and results for different flow observables. The effects of the QCD equation of state on multiparticle correlations of identified particles are determined for both AuAu $\sqrt{{s}_{\text{NN}}}=200$ GeV and PbPb $\sqrt{{s}_{\text{NN}}}=5.02$ TeV collisions. New insights into the ${v}_{2}{2}$ to ${v}_{3}{2}$ puzzle in ultracentral collisions are found. Flow observables of heavier particles exhibit more nonlinear behavior regardless of the assumptions about the equation of state, which may provide a new way to constrain the temperature dependence of $\ensuremath{\eta}/s$.

Lattice QCD Equation of State at Finite Chemical Potential from an Alternative Expansion Scheme.

Abstract: In this Letter, we introduce a novel scheme for extrapolating the equation of state of QCD to finite chemical potential that features considerably improved convergence properties and allows us to extend its reach to unprecedentedly high baryonic chemical potentials. We present continuum extrapolated lattice results for the new expansion coefficients and show the thermodynamic observables up to ${\ensuremath{\mu}}_{B}/T\ensuremath{\le}3.5$. This novel expansion does not suffer from the shortcomings that characterize the traditional Taylor expansion method, such as difficulties inherent in performing such an expansion with a limited number of coefficients and the poor signal-to-noise ratio that affects Taylor coefficients determined from lattice calculations.

전자/제조업의 Collaboration 전략

Abstract: Mental health issues often co-occur with other problems such as substance abuse, and they can take an enormous toll on individuals and impact a college or university in many ways. There are staff and departments both onand off-campus who are concerned about the well-being of students and the impact of mental health issues, so partnerships around mental health promotion and suicide prevention make good sense.

Leading hadronic contribution to the muon magnetic moment from lattice QCD

Abstract: We compute the leading order hadronic vacuum polarization (LO-HVP) contribution to the anomalous magnetic moment of the muon, $(g_\mu-2)$, using lattice QCD Calculations are performed with four flavors of 4-stout-improved staggered quarks, at physical quark masses and at six values of the lattice spacing down to 0064~fm All strong isospin breaking and electromagnetic effects are accounted for to leading order The infinite-volume limit is taken thanks to simulations performed in volumes of sizes up to 11~fm Our result for the LO-HVP contribution to $(g_\mu-2)$ has a total uncertainty of 08\% Compared to the result of the dispersive approach for this contribution, ours significantly reduces the tension between the standard model prediction for $(g_\mu-2)$ and its measurement

Search for the QCD Critical Point with Fluctuations of Conserved Quantities in Relativistic Heavy-Ion Collisions at RHIC : An Overview

Abstract: Fluctuations of conserved quantities, such as baryon, electric charge and strangeness number, are sensitive observables in relativistic heavy-ion collisions to probe the QCD phase transition and search for the QCD critical point. In this paper, we review the experimental measurements of the cumulants (up to fourth order) of event-by-event net-proton (proxy for net-baryon), net-charge and net-kaon (proxy for net-strangeness) multiplicity distributions in Au+Au collisions at $\sqrt{s_{NN}}=7.7, 11.5, 14.5, 19.6, 27, 39, 62.4, 200$ GeV from the first phase of beam energy scan program at the Relativistic Heavy-Ion Collider (RHIC). We also summarize the data analysis methods of suppressing the volume fluctuations, auto-correlations and the unified description of efficiency correction and error estimation. Based on theoretical and model calculations, we will discuss the characteristic signatures of critical point as well as backgrounds for the fluctuation observables in heavy-ion collisions. The physics implications and the future second phase of the beam energy scan (2019-2020) at RHIC will be also discussed.