arXiv subjects

Nicolò Masi

Publications and source records attributed to Nicolò Masi.

5 recordsLinked to original sources

arXiv2026

G(2) Glueball Boson Stars as Restricted Kerr Mimickers in the Thomas--Fermi Limit

We investigate whether horizonless compact stars made of dark glueball matter from a broken exceptional $G(2)$ gauge sector can reproduce selected Kerr observables within a Thomas--Fermi effective-fluid description. We introduce GC9, a scale-separated $G(2)$-inspired positive nonic-density closure whose high-density stiffness, bag-free surface and Q-ball safety make it a useful compact-star benchmark. After Thomas--Fermi rescaling, reduced stellar observables are independent of the microscopic glueball mass $m_G$, while the collective stiffness $Λ_T$ fixes the dimensional mass and radius. Solving the TOV, Hinderer and Hartle--Thorne systems, we obtain a stable maximum-mass compactness $C=0.3247$, tidal deformability $Λ=4.37$, $\bar I C^{3/2}=0.947$, and slow-rotation quadrupole $\bar Q=1.522$. At $j=0.328$, the same-order ISCO shift is $1.24\%$. The stable endpoint has no light ring, but its exterior Regge--Wheeler barrier supports a genuine static axial mode, $Mω=0.463846-0.098881i$, with a damping time about ten percent shorter than Schwarzschild and a real frequency $24.1\%$ higher. A polarization-balanced vector realization has the same isotropic bulk EOS; moderate residual anisotropy changes static and first-order observables only at the few-percent level, while the full coupled vector spectrum remains open. Cowling calculations identify matter-supported quadrupolar modes. The scalar-burst, seeded-collapse and cosmological sections are phenomenological: a fixed $Λ_T$ gives a compact Kerr-comparison branch only near its own maximum mass, so the multi-sector scenario assumes distinct constant-$Λ_T$ branches from the keV supermassive sector to the PeV asteroid-mass sector. GC9 therefore defines a falsifiable restricted Kerr-mimicry framework for gravitational-wave, horizon-scale and compact-dark-matter tests.

astro-ph.HE↗

arXiv2026

Toward a Special \textbf{$E_6\to G(2) \times SU(3)_A$} Embedding for Standard Model and Dark Matter and an $E_7$ Completion Proposal

We developed a unified framework based on a special (non-regular) embedding of the exceptional group $E_6$ in which the main stage of symmetry breaking chain realizes $E_6\to G(2) \times SU(3)_A$. The exceptional factor $G(2)$ plays the role of a hidden strong sector, while $SU(3)_A$ acts as an ancestor of the electroweak gauge group. A minimal scalar sector is organized around a $\mathbf{650}$-based $E_6$ Higgs sector. Its components $(\mathbf7,\mathbf1)$ and $(\mathbf1,\mathbf8)$ implement the subsequent breaking steps $G(2)\to SU(3)_C$ and $SU(3)_A\to SU(2)_L\times U(1)_A$. The \emph{speciality} of this symmetry breaking establishes the feature of \textit{darkness}. Defining an hypercharge from the $t_{8}$ generator of $SU(3)_A$ is not sufficient to recover the exact Standard Model hypercharges, leading to the necessity of an $E_7$ uplift which introduces a proper additional $U(1)_X$ factor. The special embedding naturally suppresses tree-level leptoquark couplings that typically mediate proton decay in regular GUTs. The scalar potential for the Higgs sectors has been constructed, deriving the heavy gauge-bosons spectrum and presenting a consistent one-loop running of the gauge couplings across the intermediate scales, which is shown to satisfy an $E_6$ unification. The exotic states are organized in $E_7$-derived vectorlike pairs and are made ultraheavy. The $G(2)$ gluons ensemble confines into heavy dark glueballs with parametrically suppressed communication with $SU(3)_A$ and $U(1)_X$ sectors. Cosmological history is analyzed, including topological defects, inflation and reheating, demonstrating that monopole relics are naturally diluted. The resulting framework provides a minimal and internally consistent exceptional apparatus which includes the Standard Model and a dark matter sector which is secluded by the group-theoretic orthogonality.

hep-ph↗

arXiv2024

The Resurgence of the G(2) Group for the Strong Sector and the Emergence of Dark Matter

G(2) is the smallest exceptional group and it is the simplest and viable gauge group to minimally extend the strong interaction sector: G(2) includes the group SU(3) of Quantum Chromodynamics (QCD) as a maximal subgroup and it is equipped with six additional gluons that can acquire mass via a Higgs mechanism driven by a new Higgs particle and constitute dark matter. In this article I want to describe how the exceptional G(2) group can be a physical gauge group, capable of extending the Standard Model (SM) of particles and including a versatile dark sector, which is compatible with experimental observations. In fact, due to its peculiar mathematical features, the group G(2) manifests some complex features, not properly considered in literature, which guarantee its correct use in physics, as its {3}+anti{3} decompositions w.r.t. SU(3) can acquire a complex structure. The resulting framework can be a solid Beyond Standard Model (BSM) solution for the dark matter (DM) problem, in the form of massive complex scalar glueballs, and it includes the proper color representations for quarks and leptons. Several quantum field theory features are discussed, like the G(2) coupling constant running and its spectrum before and after the phase transition, along with all the DM astrophysical realizations, in order to present the unexpected potential of this gauge group.

hep-ph↗

arXiv2015

Rényi entropy for particle systems as an instrument to enlarge the Boltzmannian concept of entropy: some holographic perspectives

The Rényi entropy is a mathematical generalization of the concept of entropy and it encodes the total information of a system as a funtion of its order parameter $α$. The meaning of the Rényi entropy in physics is not completely enstablished: here we determined a general and explicit representation of the Rényi entropy for whichever fluid of particles and spin-statistics, in the mechanical statistics framework. This allowed us to put physical constraints to the Rényi order $α$, from main thermodynamical relations and entropy bounds of the holographic theories, defining how much we can enlarge the Boltmannian concept of entropy.

physics.gen-ph↗

arXiv2015

A conservative assessment of the current constraints on dark matter annihilation from Cosmic Rays and CMB observations

In view of the current interest in combining different observations to constraint annihilating WIMP dark matter, we examine the relation between the Sommerfeld effect at the recombination epoch and in the galactic halo. By considering an up-to-date collection of interpolations of cosmic rays lepton data (AMS-02 2014, Fermi and PAMELA), as dark matter annihilation signals, we show that current cosmic rays measurements and recent Planck 2015 constraints from CMB anisotropies almost overlap for dark matter masses of the order of few $TeV$, although great theoretical uncertainties afflict cosmic rays and dark matter descriptions. Combining cosmic rays fits we obtain proper minimal regions allowed by CMB observations, especially for $μ$ and $τ$ annihilation channels, once assumed viable values of the efficiency factor for energy absorption at recombination: the results are consistent with those obtained by the Planck collaboration but allow a slightly larger overlap between Cosmic Rays constraints from the lepton sector and CMB. Incoming AMS-02 measurements of cosmic rays antiprotons will help to clarify the conundrum.

astro-ph.CO↗