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Abstract In the last decade a quasi-particle model (QPM) has supplied the basis for the study of heavy quark (HQ) production in ultra-relativistic collisions, allowing for a phenomenological estimate of the HQ diffusion coefficient $$D_s(T)$$ D s ( T ) . Using the new lattice QCD results for the equation of state (EoS) with 2+1+1 dynamical flavors, we extend the QPM from $$N_f=2+1$$ N f = 2 + 1 to $$N_f=2+1+1$$ N f = 2 + 1 + 1 , where the charm quark is included. Fixing the coupling g(T) by a fit to the lQCD energy density $$\epsilon (T)$$ ϵ ( T ) , we evaluate the impact of different temperature parametrizations of charm quark mass on EoS and susceptibilities $$\chi _q(T)$$ χ q ( T ) of light, $$\chi _s(T)$$ χ s ( T ) of strange and $$\chi _c(T)$$ χ c ( T ) of charm quarks, the last favouring a charm quark mass increasing toward $$T_c$$ T c . We also explore the extension of the QPM to a more realistic approach called QPM $$_p$$ p , where quark and gluon masses explicitly depend on their momentum converging to the current quark mass at high momenta, as expected from asymptotic free dynamics. The QPM $$_p$$ p allows for a simultaneous quantitative description not only of the EoS but also of the quark susceptibilities ( $$\chi _q(T)$$ χ q ( T ) , $$\chi _s(T)$$ χ s ( T ) ), which instead are underestimated in the simple QPM. Furthermore, evaluating the spatial diffusion coefficient $$2\pi T D_s(T)$$ 2 π T D s ( T ) in the QPM $$_p$$ p , we find it is also closer than QPM to the recent lQCD data performed including dynamical fermions. Finally, in a 1+1D expanding system, we evaluate the $$R_{AA}(p_T)$$ R AA ( p T ) in the QPM and QPM $$_p$$ p , finding a significant reduction at low momenta for QPM $$_p$$ p which could lead in a realistic scenario to a better agreement to experimental data.

Abstract We study the universal behavior associated with a Relativistic Boltzmann Transport (RBT) approach with the full collision integral in 0+1D conformal systems. We show that all momentum moments of the distribution function exhibit universal behavior. Furthermore, the RBT approach allows to calculate the full distribution function, showing that an attractor behavior is present in both the longitudinal and transverse momentum dependence. We compare our results to the far-from-equilibrium attractors determined with other approaches, such as kinetic theory in Relaxation Time Approximation (RTA) and relativistic hydrodynamic theories, both in their viscous (DNMR) an anisotropic (aHydro) formulations, finding a very similar evolution, but an even faster thermalization in RBT for higher order moments. For the first time, we extended this analysis also to study the attractor behavior under a temperature-dependent viscosity $$\eta /s(T)$$ η / s ( T ) , accounting also for the rapid increase toward the hadronic phase. We find that a partial breaking of the scaling behavior with respect to $$\tau /\tau _{eq}$$ τ / τ eq emerges only at $$T \approx T_c$$ T ≈ T c generating a transient deviation from attractors; interestingly this in realistic finite systems may occur around the freeze-out dynamics. Finally, we investigate for the first time results beyond the boost-invariant picture, finding that also in such a case the system evolves toward the universal attractor. In particular, we present the forward and pull-back attractors at different space-time rapidities including rapidity regions where initially the distribution function is even vanishing.

Abstract This paper is a write-up of the ideas that were presented, developed and discussed at the fourth International Workshop on QCD Challenges from pp to AA, which took place in February 2023 in Padua, Italy. The goal of the workshop was to focus on some of the open questions in the field of high-energy heavy-ion physics and to stimulate the formulation of concrete suggestions for making progresses on both the experimental and theoretical sides. The paper gives a brief introduction to each topic and then summarizes the primary results.

Abstract We study the production of charmed and multi-charmed hadrons in ultra-relativistic Heavy Ion Collisions coupling the transport approach for charm dynamics in the medium to an hybrid hadronization model of coalescence plus fragmentation. In this paper, we mainly discuss the particle yields for single charmed and multi-charmed baryons focusing mainly on the production of $$\Xi _{cc}$$ Ξ cc and $$\Omega _{ccc}$$ Ω ccc . We provide first predictions for PbPb collision in $$0 \! - \! 10\%\ $$ 0 - 10 % centrality class and then we explore the system size dependence through KrKr , to ArAr and OO collisions, planned within the ALICE3 experiment. In these cases, a monotonic behavior for the yields emerges which can be tested in future experimental data. We found about three order of magnitude increase in the production of $$\Omega _{ccc}$$ Ω ccc in PbPb collisions compared with the yield in small collision systems like OO collisions. Furthermore, we investigate the effects on the $$\Omega _{ccc}$$ Ω ccc particle yield and spectra coming from the modification of the charm quark distribution due to the different size of the collision systems also comparing it to the case of thermalized charm distributions. These results suggest that observation on the $$\Omega _{ccc}$$ Ω ccc spectra and their evolution across system size can give novel information about the partial thermalization of the charm quark distribution as well as to its wave function width. Furthermore, we find that the $$\Omega _{ccc}$$ Ω ccc / $$D^0$$ D 0 ratio is an observable more sensitive with respect to $$\Lambda _c$$ Λ c / $$D^0$$ D 0 , this ratio is predicted to span over two order of magnitude from large to small systems.

The high frequency and complexity of mandibular third molar (M3M) surgery have led several authors to the development of classification systems for better evaluation and management in oral surgery. This study compared the classifications of Juodzabalys and Daugela et al. (JD), Sammartino et al., Chang et al., Jhamb et al., Maglione et al., and Nemsi et al. to understand the concordance between the scores of M3M surgery. Two types of analysis were conducted: the relationship between the M3M and the inferior alveolar nerve (IAN), and the overall difficulty score based on the tooth’s angulation and its spatial position with the adjacent structure. The analysis of the classifications on the relationship between M3M and IAN resulted in a concordance of 26.1%. In the pairwise comparisons, the classifications of Nemsi et al. and Jhamb et al. showed the highest concordance of 59.5%. Analyzing the total scores difficulty, the JD et al., Chang et al., and Sammartino et al. classifications demonstrated a concordance level of 25.5%. A pairwise assessment revealed a higher concordance degree between the classifications of Sammartino et al. and Chang et al. (57.4%). The results highlight the limits in establishing a comprehensive and objective classification for the surgical difficulty of M3M, possibly attributed to variations in the methodology for computing total scores. An objective, automated, and non-operator-dependent classification method for assessing the surgical difficulty of M3M is still needed.

In the last decade a Quasi-Particle Model (QPM) has been developed to study charm quark dynamics in ultra-relativistic heavy-ion collisions supplying a satisfactory description of the main observables for D meson and providing an estimate of the space-diffusion coefficient Ds(T) from the phenomenology. In this paper, we extend the approach to bottom quarks describing their propagation in the quark-gluon plasma within an event-by-event full Boltzmann transport approach followed by a coalescence plus fragmentation hadronization. We find that QPM approach is able to correctly predict the first available data on RAA(pT) and v2(pT) of single-electron from B decays without any parameter modification w.r.t. the charm. We show also predictions for centralities where data are not yet available for both v2(pT) and v3(pT). Moreover, we discuss the significant breaking of the expected scaling of the thermalization time τth with MQ/T, discussing the evolution with mass of Ds(T) to better assess the comparison to lQCD calculations. We find that at T=Tc charm quark Ds(T) is about a factor of 2 larger than the asymptotic value for M→∞, while bottom Ds(T) is only a 20% higher. This implies a Ds(T) which is consistent within the current uncertainty to the most recent lattice QCD calculations with dynamical quarks for M→∞.

Abstract We describe the propagation of charm quarks in the quark-gluon plasma (QGP) by means of an event-by-event transport approach. In our calculations the non-perturbative interaction between heavy quarks and light partons has been taken into account through a quasi-particle approach with thermal light quark masses tuned to reproduce lQCD thermodynamics. We found that the flow observables $$v_2$$ v 2 and $$v_3$$ v 3 of D mesons are comparable with the experimental measurements for Pb + Pb collisions at 5.02 TeV in different ranges of centrality selections. The results are analyzed with event-shape engineering technique. The comparison of the anisotropic flow coefficients $$v_n$$ v n with experimental data show a quite good agreement with experimental data for different flow vector $$q_2$$ q 2 selections, which confirms the strong coupling between charm quarks and light quarks in the QCD matter. Furthermore, we present here a novel study of the event-by-event correlations between flow harmonics of D mesons and soft hadrons at LHC energy with the event-shape engineering technique that can put further constraints on heavy quark transport coefficients toward a solid comparison between the phenomenological determination and the lattice QCD calculations.

Objective:. To evaluate the influence of enhanced recovery pathway (ERP) on patient-reported outcome measures (PROMs) and return to intended oncologic therapy (RIOT) after colorectal surgery. Background:. ERP improves early outcomes after colorectal surgery; however, little is known about its influence on PROMs and on RIOT. Methods:. Prospective multicenter enrollment of patients who underwent colorectal resection with anastomosis was performed, recording variables related to patient-, institution-, procedure-level data, adherence to the ERP, and outcomes. The primary endpoints were PROMs (administered before surgery, at discharge, and 6 to 8 weeks after surgery) and RIOT after surgery for malignancy, defined as the intended oncologic treatment according to national guidelines and disease stage, administered within 8 weeks from the index operation, evaluated through multivariate regression models. Results:. The study included 4529 patients, analyzed for PROMs, 1467 of which were analyzed for RIOT. Compared to their baseline preoperative values, all PROMs showed significant worsening at discharge and improvement at late evaluation. PROMs values at discharge and 6 to 8 weeks after surgery, adjusted through a generalized mixed regression model according to preoperative status and other variables, showed no association with ERP adherence rates. RIOT rates (overall 54.5%) were independently lower by aged > 69 years, ASA Class III, open surgery, and presence of major morbidity; conversely, they were independently higher after surgery performed in an institutional ERP center and by ERP adherence rates > median (69.2%). Conclusions:. Adherence to the ERP had no effect on PROMs, whereas it independently influenced RIOT rates after surgery for colorectal cancer.

Abstract We present a study of the directed flow v 1 for D mesons discussing both the impact of initial vorticity and electromagnetic field. Recent studies predicted that v 1 for D mesons is expected to be surprisingly much larger than that of light charged hadrons; we clarify that this is due to a different mechanism leading to the formation of a directed flow with respect to the one of the bulk matter at both relativistic and non-relativistic energies. We point out that the very large v 1 for D mesons can be generated only if there is a longitudinal asymmetry between the bulk matter and the charm quarks and if the latter have a large non-perturbative interaction in the QGP medium. A quite good agreement with the data of STAR and ALICE is obtained if the diffusion coefficient able to correctly predict the R AA (p T ), v 2(p T ) and v 3(p T ) of D meson is employed. Furthermore, the mechanism for the build-up of the v 1(y) is associated to a quite small formation time that can be expected to be more sensitive to the initial high-temperature dependence of the charm diffusion coefficient. We discuss also the splitting of v 1 for D 0 and D ¯ 0 $$ {\overline{D}}^0 $$ due to the electromagnetic field that is again much larger than the one observed for charged particles and in agreement with the data by STAR that have however still error bars comparable with the splitting itself, while at LHC standard electromagnetic profile assuming a constant conductivity is not able to account for the huge splitting observed.

Abstract We evaluate drag and diffusion transport coefficients comparing a quasi-particle approximation with on-shell constituents of the QGP medium and a dynamical quasi-particles model with off-shell bulk medium at finite temperature T. We study the effects of the width $$\gamma $$ γ of the particles of the bulk medium on the charm quark transport properties exploring the range where $$\gamma < M_{q,g}$$ γ < M q , g . We find that off-shell effects are in general quite moderate and can induce a reduction of the drag coefficient at low momenta that disappear already at moderate momenta, $$p \gtrsim $$ p ≳ 2–3 GeV. We also observe a moderate reduction of the breaking of the fluctuation–dissipation theorem (FDT) at finite momenta. Moreover, we have performed a first study of the dynamical evolution of HQ elastic energy loss in a bulk medium at fixed temperature extending the Boltzmann (BM) collision integral to include off-shell dynamics. A comparison among the Langevin dynamics, the BM collisional integral with on-shell and the BM extension to off-shell dynamics shows that the evolution of charm energy when off-shell effects are included remain quite similar to the case of the on-shell BM collision integral.

An extraordinary strong magnetic field, eB0≈1018 Gauss, is expected to be generated in non-central ultrarelativistic heavy ion collisions and it is envisaged to induce several effects on hot QCD matter including the possibility of local parity and local charge conjugation and parity symmetry violations. A direct signature of such e.m. fields and a first quantitative measurement of its strength and lifetime are still missing. We point out that both the mean value of leptonic invariant mass of Z0 boson, reconstructed by its decaying lepton pairs, and the relative width are modified in relativistic heavy ion collisions due to the presence of strong initial e.m. fields. We propose a measurement of the leptonic invariant mass of Z0 as a novel probe of the strength of the By. Both shifts could be up to about few hundred MeV and are found to depend on the integral of By over the time duration quadratically (approximate). Hence it provides a novel and clear probe of electromagnetic fields, which can be tested experimentally.

Abstract We have developed a relativistic transport approach at fixed $$\eta /s(T)$$ η/s(T) that incorporates initial space fluctuations generated by wounded quark model to study the hadron observables in 5.02 TeV p + Pb collisions. We find that our approach is able to correctly predict quite well several existing experimental measurements assuming a matter with $$\eta /s=1/4\pi $$ η/s=1/4π , a result similar to previous studies within a viscous hydrodynamics approach. Besides, we further discuss the sensitivity of the results on both $$\eta /s(T)$$ η/s(T) and the smearing width. Our transport approach has the possibility to include in initial conditions the power law tail associated to minijet, and this improvement extends the agreement with the experimental data to higher $$p_T$$ pT ranges. We also perform a comparison to Pb + Pb collisions pointing out that even if the collective flows have a similar magnitude the features of the matter created are different. By studying the correlation between collective flows and initial geometry, we find that the correlation decreases faster in small systems with the increase of n and centrality. In particular we show that the variance of $$\sigma _{v_n}/\langle v_n\rangle $$ σvn/⟨vn⟩ has a quite different evolution with centrality for p + Pb, so their measurement could provide some further hint about the correctness of current modelling.

The COVID19 infection is known to disseminate through droplets ejected by infected individuals during coughing, sneezing, speaking, and breathing. The spread of the infection and hence its menace depend on how the virus-loaded droplets evolve in space and time with changing environmental conditions. In view of this, we investigate the evolution of the droplets within the purview of the Brownian motion of the evaporating droplets in the air with varying weather conditions under the action of gravity. We track the movement of the droplets until either they gravitationally settle on the ground or evaporate to aerosols of size 2 μm or less. Droplets with radii 2 μm or less may continue to diffuse and remain suspended in the air for a long time. The effects of relative humidity and temperature on the evaporation are found to be significant. We note that under strong flowing conditions, droplets travel large distances. It is found that the bigger droplets fall on the ground due to the dominance of gravity over the diffusive force despite the loss of mass due to evaporation. The smaller evaporating droplets may not settle on the ground but remain suspended in the air due to the dominance of the diffusive force. The fate of the intermediate size droplets depends on the weather conditions and plays crucial roles in the spread of the infection. These environment dependent effects indicate that the maintenance of physical separation to evade the virus is not corroborated, making the use of face masks indispensable.

The recent experimental measurements on pp collisions at s=5.02TeV have shown a very large production of heavy baryons corresponding to a Λc/D0 ratio of about 0.5. This ratio is about one order of magnitude larger than what measured in e+e−, ep collisions, and is larger of about a factor two respect to the forward rapidity ratio in pp collisions at LHC. We apply for the first time to pp collisions a quark coalescence plus fragmentation approach developed for AA collisions, assuming the formation of Hot QCD matter at finite temperature, which was able to correctly predict a Λc/D∼O(1) in AA collisions at RHIC energy. We calculate the heavy baryon/meson ratio and the pT spectra of charmed hadrons with and without strangeness content: D0, Ds, Λc+, Ξc and Ωc in pp collisions at top LHC energies, finding a satisfactory result for the measured Λc+/D0 and the Ξc/D0. At variance with other approaches a coalescence approach predicts also a significant production of Ωc such that Ωc/D0∼O(10−1).

Ultrarelativistic heavy ion collisions are expected to generate a huge electromagnetic field, eB≈1018Gauss, that induces a splitting of the directed flow, v1=〈px/pT〉, of charged particles and anti-particles. Such a splitting for charmed meson manifests even for neutral particle/anti-particles pairs (D0,D‾0), hence being also a unique probe of the formation of the quark-gluon plasma phase. For the first time here we show that electromagnetic field may generate a v1(D0)−v1(D‾0) as huge as the one recently observed at LHC against early expectations.Within this new research topic we point out a novel measurement: v1 of leptons from Z0 decay and its correlation to that of D and B mesons. The correlation for Δv1 of l+−l−, D0−D‾0 and B0−B‾0 would provide a strong probe of the electromagnetic origin of the splitting and hence of the formation of a quark-gluon plasma phase with heavy quarks as degrees of freedom. The case of the v1(l±) presents features due to the peculiar form of the pT spectrum never appreciated before in the study of heavy ion collisions. We specifically predict a sudden change of the Δv1(pT) of leptons at pT=45GeV/c, that can be traced back to a universal relation of Δv1 with the slope of the pT particle distribution and the integrated effect of the Lorentz force.

The heavy quarks (HQs) are a unique probe of the hot QCD matter properties and their dynamics are coupled to the locally thermalized expanding quark gluon plasma. We present here a novel study of the event by event correlations between light and heavy flavor flow harmonics at LHC energy within a transport approach. Interaction between heavy quarks and light quarks have been taken into account to explore the impact of different temperature dependence for transport coefficients Ds and Γ. Our study indicates that vnheavy−vnlight correlation and the relative fluctuations of anisotropic flows, σvn/〈vn〉, are novel observables to understand the heavy quark-bulk interaction and are sensitive to the temperature dependence even to moderate differences of Ds(T), or Γ(T). Hence, the comparison of such new HQ observables to upcoming experimental data at both RHIC and LHC energies can put further constraints on heavy quark transport coefficients and in particular on its temperature dependence toward a solid comparison between phenomenological determination and lattice QCD calculations.

In the pre-thermal equilibrium stage of relativistic heavy-ion collisions, a strong quasi-classical transverse gluon field emerges at about τ0≃0.1fm/c and evolves together with their longitudinal counterparts according to the classical Yang-Mills (CYM) equations. Recently it has been shown that these fields induce a diffusion of charm quarks in momentum space resulting in a tilt of their spectrum without a significant drag. We find that in nucleus-nucleus collisions at LHC such a novel dynamics of charm quarks leads to an initial enhancement of the nuclear modification factor (RAA) at pT larger than 2GeV/c contrary to the standard lore. Moreover, the same dynamics leads to a larger final elliptic flow (v2) inducing a relation between RAA and v2 that is quite close to the experimental measurements. Our study also shows that such an initial pre-thermal stage is unlikely to be described in terms of a standard drag and diffusion dynamics, because even if one tune such coefficients to reproduce the same RAA(pT) this would imply a significantly smaller v2.

The heavy quarks constitute a unique probe of the quark–gluon plasma properties. A puzzling relation between the nuclear modification factor RAA(pT) and the elliptic flow v2(pT) has been observed both at RHIC and LHC energies. Predicting correctly both observables has been a challenge to all existing models, especially for D mesons. We discuss how the temperature dependence of the heavy quark drag coefficient is responsible for a large part of such a puzzle. In particular, we have considered four different models to evaluate the temperature dependence of drag and diffusion coefficients propagating through a quark gluon plasma (QGP). All the four different models are set to reproduce the same RAA(pT) observed in experiments at RHIC and LHC energy. We point out that for the same RAA(pT) one can generate 2–3 times more v2 depending on the temperature dependence of the heavy quark drag coefficient. A non-decreasing drag coefficient as T→Tc is a major ingredient for a simultaneous description of RAA(pT) and v2(pT).