arXiv subjects

Federico Nola

Publications and source records attributed to Federico Nola.

7 recordsLinked to original sources

arXiv2026

An EOS-Driven Extension of NSCool for Compact Star Cooling with Hadronic and Quark Degrees of Freedom

We present an EOS-driven extension of the NSCool thermal evolution code that enables complete tabulated equations of state to be treated within a single composition-based input structure. The generalized NEW interface includes additional baryonic fractions, a bosonic composition variable, the hadronic volume fraction, and quark fractions, allowing nucleonic, hyperonic, resonant-baryonic and hybrid hadron-quark configurations to be handled within the same workflow. The neutrino sector is extended accordingly, including updated nucleonic modified Urca and bremsstrahlung rates, additional baryonic direct Urca channels, hyperonic processes, baryonic pair breaking and formation and quark direct Urca, modified Urca, bremsstrahlung and PBF contributions. In mixed phases, emissivities and the corresponding core heat capacity contributions are evaluated from phase-local quantities and combined using the hadronic volume fraction. The implementation is validated against the original NSCool calculation for a controlled nucleonic benchmark and demonstrated with representative hadronic and quark-containing EOSs. These calculations are intended as software validation tests of the generalized workflow rather than as observational fits or statistical EOS inference.

nucl-th↗

arXiv2026

Trace Anomaly and Effective Topological Sources in Neutron Stars

This work investigates whether the trace anomaly can diagnose the stellar response to a topological scalar field in tensor multi-scalar gravity. Eleven cold tabulated equations of state (EoSs) were examined, with six retained after general relativistic (GR) thermodynamic and causality checks. Their fiducial topological configurations were compared with the corresponding GR models under complementary matching prescriptions. After controlling for stellar mass and EoS dependence, the GR trace source strength $S_T$ remained strongly correlated with the topological mass response, with a partial Spearman coefficient $ρ=0.975$. Near $1.4\,M_\odot$, the topological configurations were systematically more compact, with Jordan frame radius reductions of $6.7$--$8.7\%$ at fixed baryonic mass and $0.87$--$1.29\,\mathrm{km}$ at fixed gravitational mass. These shifts are comparable to current uncertainties from the Neutron Star Interior Composition Explorer (NICER) and produce source dependent observational effects. Despite the global deformation, the interior effective source remained matter dominated, with a median topological contribution of about $0.8\%$. The GR matter trace therefore emerges as a useful diagnostic of the fiducial topological stellar response.

nucl-th↗

arXiv2026

From $χ$EFT to Multi-Region Modeling: Neutron star structure with a polytropic extension of $χ$EFT and MUSES Calculation Engine multi-layer modeling

Neutron stars provide a unique environment to probe the properties of dense nuclear matter. In this work, we present a comparative study between two approaches to modeling the neutron star structure: a Chiral Effective Field Theory based approach and the MUSES Calculation Engine framework, which uses three different approaches for the three density regions. We analyze the resulting mass-radius relations, discussing the respective advantages and limitations of the two methods.

nucl-th↗

arXiv2026

Core Composition Effects on the QCD Axion Mass Limit from Neutron Star Cooling

Neutron stars are very dense media in which axions may be produced. This has been used to set limit on the QCD axion mass, usually under the assumption that only neutrons, protons, electrons, and muons appear in the star core. Given the extreme conditions reached within neutron stars, it is reasonable to consider that other particles, such as hyperons and $Δ$ resonances, may exist on-shell. In this work, we study how the limit on the mass of QCD axions, namely KSVZ and DFSZ invisible axions, is altered when different equations of state are used, allowing for heavier particles to appear in the neutron star core. We find that this dependence is in general mild and thus reinforces the reliability of the known limit. Additionally, in the DFSZ scenario, it may drive the limit within the sensitivity window for IAXO. This would allow this experiment to discern the composition of neutron star cores if an axion were to be observed within that window.

hep-ph↗

arXiv2026

NICER Constraints on Low density Interpolation and High density Continuation in Neutron Star Equations of State

We investigate whether current astrophysical data constrain not only the high density continuation of the neutron star equation of state, but also the low density matching procedure itself. To this end, we compare two low density branches propagated through a common high density extension and confront them with direct NICER mass-radius posteriors, a lower bound on the maximum mass, and an effective constraint on $Λ_{1.4}$. We find that the observable predictions of the two branches remain strongly overlapping, while the NICER-informed posterior still induces a nontrivial constraint on the matching parameters. Current data therefore constrain primarily the shared continuation above $n_1$, but also indirectly restrict the low-density matching sector.

nucl-th↗

arXiv2026

Experimental exclusion of a generalized Károlyházy gravity-induced decoherence model

We report new experimental constraints on the generalized version of the gravity-induced decoherence model originally proposed by Károlyházy. Using data collected by the VIP Collaboration at the INFN Gran Sasso National Laboratory with a high-purity germanium detector, we derive an improved lower bound on the spatial correlation length $R_K$ characterizing metric fluctuations in the model. We obtain a bound $R_K > 4.64$ m (95\% C.L.), which exceeds by more than an order of magnitude the previous experimental limit. When combined with the theoretical upper bound $R_K <1.98$ m derived from macroscopic localization requirements, our result excludes the generalized Károlyházy model. The same conclusion applies to an associated non-Markovian formulation of the Continuous Spontaneous Localization (CSL) model. Our findings significantly tighten experimental constraints on gravity-related decoherence scenarios and demonstrate the sensitivity of underground low-background experiments to foundational modifications of quantum mechanics.

quant-ph↗

arXiv2025

Machine Learning Optimization of BEGe Detector Event Selection in the VIP Experiment

The VIP collaboration operates a Broad Energy Germanium detector at the Gran Sasso National Laboratory to measure radiation in the few keV to 100 keV range, aiming to search for spontaneous collapse induced radiation and atomic transitions that violate the Pauli Exclusion Principle. Here we present a machine learning based upgrade for the BEGe detector using an event selection strategy aimed at improving the efficiency in detecting low energy events down to 10 keV. The method employs a denoising autoencoder to suppress electronic and microphonic noises and to reconstruct pulse shapes, followed by a convolutional neural network that classifies waveforms as normal single site or events with anomalies. The workflow was validated on a dataset comprising more than 20000 waveforms recorded in 2021. The classifier achieves a receiver operating characteristic curve with an area under the curve of 0.99 and an accuracy of 95 percent. Applying this procedure lowers the minimum detectable energy of the final spectrum to approximately 10 keV. It also yields a measurable enhancement in spectral quality, including an improvement of about 14 percent in the signal to background ratio and a reduction of the energy resolution for the characteristic Pb and Bi gamma lines. These developments enhance the sensitivity of the BEGe detector to rare low energy signals and provide a scalable framework for future precision tests of quantum foundations in low background environments.

physics.ins-det↗