arXiv subjects

Paolo Cea

Publications and source records attributed to Paolo Cea.

At least 19 recordsLinked to original sources

arXiv2025

Flux tubes in QCD at finite temperature

We present results for the chromo-electric field generated by a static quark-antiquark pair at finite temperature, in lattice QCD with 2+1 dynamical staggered fermions at physical quark masses. We investigate the evolution of the field as the temperature increases through and beyond the chiral transition. For all the temperatures considered we find clear evidence of a chromo-magnetic current and of a longitudinal nonperturbative chromo-electric field that stays almost uniform along the flux tube. In the high-temperature region the magnitude of the flux-tube field is determined by an effective string tension that decreases exponentially as the temperature increases, while the flux-tube width decreases according to an inverse-temperature law. Our results suggest that beyond the chiral pseudocritical temperature the quark-antiquark system can be characterized by a screened string tension.

hep-lat↗

arXiv2024

Investigating the flux tube structure within full QCD

A characteristic signature of quark confinement is the concentration of the chromoelectric field between a static quark-antiquark pair in a flux tube. Here we report on lattice measurements of field distributions on smeared Monte Carlo ensembles in QCD with (2+1) HISQ flavors. We measure the field distributions for several distances between static quark-antiquark sources, ranging from 0.6 fm up to the distance where the color string is expected to break.

hep-lat↗

arXiv2024

QCD with (2+1) flavors at the physical point in external chromomagnetic fields

We investigate full QCD with (2+1)-flavour of HISQ fermions at the physical point in the presence of uniform Abelian chromomagnetic background fields. Our focus is on the renormalized light and strange chiral condensate around the pseudo-critical temperature. We find that in the confined region the gauge system is subjected to the chromomagnetic catalysis that turns into the inverse catalysis in the high-temperature regime. We further observe that the chiral condensates are subjected to the so-called thermal hysteresis. Our estimate of the deconfinement temperature indicates that the critical temperature begins to decrease in the small field region, soon after it seems to saturate and finally increase with the strength of the chromomagnetic field.

hep-lat↗

arXiv2023

The QCD vacuum as a disordered chromomagnetic condensate

An attempt is made to describe from first principles the large-scale structure of the confining vacuum in quantum chromodynamics. Starting from our previous variational studies of the SU(2) pure gauge theory in an external Abelian chromomagnetic field and extending the Feynman's qualitative analysis in (2+1)-dimensional SU(2) gauge theory, we show that the SU(3) vacuum in three-space and one-time dimensions behaves like a disordered chromomagnetic condensate. Color confinement is assured by the presence of a mass gap together with the absence of color long-range correlations. We offer a clear physical picture for the formation of the flux tube between static quark charges that allowed to determine the color structure and the transverse profile of the flux-tube chromoelectric field. The transverse profile of the flux-tube chromoelectric field turns out to be in reasonable agreement with lattice data. We, also, show that our quantum vacuum allows for both the color and ordinary Meissner effect. We find that for massless quarks the quantum vacuum could accommodate a finite non-zero density of fermion zero modes leading to the dynamical breaking of the chiral symmetry.

hep-ph↗

arXiv2022

The Higgs condensate as a quantum liquid: A critical comparison with observations

The triviality of four-dimensional scalar quantum field theories poses challenging problems to the usually adopted perturbative implementation of the Higgs mechanism. In the first part of the paper we compare the triviality scenario and the renormalised two-loop perturbation theory to precise and extensive results from non-perturbative numerical simulations of the real scalar field theory on the lattice. The proposal of triviality and spontaneous symmetry breaking turns out to be in good agreement with numerical simulations, while the renormalised perturbative approach seems to suffer significant deviations from the numerical simulation results. In the second part of the paper we try to illustrate how the triviality of four-dimensional scalar field theory leads, nevertheless, to the spontaneous symmetry breaking in the scalar sector of the Standard Model. We show how triviality allows us to develop a physical picture of the Higgs mechanism in the Standard Model. We suggest that the Higgs condensate behave like a relativistic quantum liquid leading to the prevision of two Higgs bosons. The light Higgs boson resembles closely the new LHC narrow resonance at 125 GeV. The heavy Higgs boson is a rather broad resonance with mass of about 730 GeV. We critically compare our proposal to the complete LHC Run 2 data collected by the ATLAS and CMS Collaborations. We do not find convincingly evidences of the heavy Higgs boson in the ATLAS datasets. On the other hand, the CMS full Run 2 data display evidences of a heavy Higgs boson in the main decay modes $H \rightarrow WW$, while in the preliminary Run 2 data there are hints of the decays $H \rightarrow ZZ$ in the golden channel. We also critically discuss plausible reasons for the discrepancies between the two LHC experiments.

hep-ph↗

arXiv2022

Is the Observable Universe Consistent with the Cosmological Principle?

The Cosmological Principle (CP) -- the notion that the Universe is spatially isotropic and homogeneous on large scales -- underlies a century of progress in cosmology. It is conventionally formulated through the Friedmann-Lema\^itre-Robertson-Walker (FLRW) cosmologies as the spacetime metric, and culminates in the successful and highly predictive $\Lambda$-Cold-Dark-Matter ($\Lambda$CDM) model. Yet, tensions have emerged within the $\Lambda$CDM model, most notably a statistically significant discrepancy in the value of the Hubble constant, $H_0$. Since the notion of cosmic expansion determined by a single parameter is intimately tied to the CP, implications of the $H_0$ tension may extend beyond $\Lambda$CDM to the CP itself. This review surveys current observational hints for deviations from the expectations of the CP, highlighting synergies and disagreements that warrant further study. Setting aside the debate about individual large structures, potential deviations from the CP include variations of cosmological parameters on the sky, discrepancies in the cosmic dipoles, and mysterious alignments in quasar polarizations and galaxy spins. While it is possible that a host of observational systematics are impacting results, it is equally plausible that precision cosmology may have outgrown the FLRW paradigm, an extremely pragmatic but non-fundamental symmetry assumption.

astro-ph.CO↗

arXiv2022

The Higgs condensate as a quantum liquid: Comparison with the full Run 2 CMS data

We compare our proposal for an additional heavy Standard Model Higgs boson to the available full data set collected by the CMS detector during Run 2 at the Large Hadron Collider (LHC) corresponding to an integrated luminosity of 138 fb$^{-1}$. The CMS Collaboration performed a search for a high mass Higgs boson decaying into a pair of W bosons in the dileptonic channel. Our analysis of the CMS data indicated the presence of a broad excess in the mass range 600 GeV - 800 GeV with respect to the expected Standard Model background with a rather significative statistical significance. We found that our theoretical proposal is in reasonable agreement with the experimental observations.

hep-ph↗

arXiv2022

CMB two-point angular correlation function in the Ellipsoidal Universe

We suggest that the Ellipsoidal Universe cosmological model, proposed several years ago to account for the low quadrupole temperature-temperature correlation of the Cosmic Microwave Background, can also provide temperature-temperature two-point angular correlation function in reasonable agreement with Planck observations.

astro-ph.CO↗

arXiv2022

The Ellipsoidal Universe and the Hubble tension

The Hubble tension resides in a statistically significant discrepancy between early time and late time determinations of the Hubble constant. We discuss the Hubble tension within the Ellipsoidal Universe cosmological model. We suggest that allowing small anisotropies in the large-scale spatial geometry could alleviate the tension. We, also, show that the discrepancy in the measurements of the Hubble constant is reduced to a statistically acceptable level if we assume sizeable cosmological anisotropies during the Dark Age. In addition, we argue that the Ellipsoidal Universe cosmological model should resolve the $S_8$ tension.

astro-ph.CO↗

arXiv2021

The Higgs condensate as a quantum liquid: Comparison with the ATLAS full Run 2 data

Recently, we proposed to picture the Higgs condensate of the Standard Model as a quantum liquid analogous to the superfluid Helium II. In this scenario the Higgs condensate excitations resemble closely two Standard Model Higgs bosons. The lightest Higgs boson was already identified with the LHC narrow resonance at 125 GeV. Concerning the heavy Higgs boson, we found preliminary evidence in our previous phenomenological analysis in the so-called golden channel. In the present note we compared our proposal to the full Run 2 data set released recently by the ATLAS Collaboration. Even though we do not found a clear statistical evidence for our Standard Model heavy Higgs, we found that our theoretical proposal is still in accordance with the available observations.

hep-ph↗

arXiv2021

On the neutron lifetime anomaly

We suggest that the neutron lifetime anomaly can be resolved by invoking the Casimir effect for trapped ultracold neutrons. Our proposal can be checked experimentally by precise lifetime measurements of trapped ultracold neutrons with different trapping volumes.

physics.gen-ph↗

arXiv2020

P-stars in the gravitational wave era

P-stars are compact relativistic stars made of deconfined up and down quarks in a chromomagnetic condensate proposed by us long time ago. P-stars do not admit a critical mass thereby they are able to overcome the gravitational collapse to black holes. In this work we discuss in greater details our theoretical proposal for P-stars. We point out that our theory for compact relativistic stars stems from our own understanding of the confining quantum vacuum supported by estensive non-perturbative numerical simulations of Quantum ChromoDynamics on the lattice. We compare our proposal with the constraints arising from the recent observations of massive pulsars, the gravitational event GW170817 and the precise determination of the PSR J0030+0451 mass and radius from NICER data. We argue that core-collapsed supernovae could give rise to a P-star instead of a neutron star. In this case we show that the birth of a P-star could solve the supernova explosion problem leading to successful supernova explosions with total energies up to $10^{53}$ erg. We critically compare P-stars with the gravitational wave event GW170817 and the subsequent electromagnetic follow-up, the short Gamma Ray Burst GRB170817A and the kilonova AT2017gfo. We also present an explorative study on gravitational wave emission from coalescing binary P-stars with masses $M_1 \simeq M_2 \simeq 30 \; M_{\odot}$. We attempt a qualitative comparison with the gravitational wave event GW150914. We find that the gravitational wave strain amplitude from massive P-star binaries could mimic the ringdown gravitational wave emission by coalescing black hole binaries. We point out that a clear signature for massive P-stars would be the detection of wobble frequencies in the gravitational wave strain amplitude in the post-merger phase of two coalescing massive compact objects with unequal masses.

astro-ph.HE↗

arXiv2020

The Higgs condensate as a quantum liquid

We model the Higgs condensate of the Standard Model as a relativistic quantum fluid analogous to superfluid helium. We find that the low-lying excitations of the Higgs condensate behave like two relativistic Higgs fields. The lighter Higgs boson has a mass of order $10^2$ GeV. We identify this light Higgs particle with the new LHC resonance at 125 GeV. The heavy Higgs boson has a mass around 750 GeV consistent with our recent phenomenological analysis of the preliminary LHC Run 2 data in the golden channel. We critical compare our theoretical scenario with two Higgs bosons to the available LHC Run 2 data.

hep-ph↗

arXiv2019

Two mass scales for the Higgs field?

In the original version of the theory, the driving mechanism for spontaneous symmetry breaking was identified in the pure scalar sector. However, this old idea requires a heavy Higgs particle that, after the discovery of the 125 GeV resonance, seems to be ruled out. We argue that this is not necessarily true. If the phase transition is weakly first order, as indicated by most recent lattice simulations, one should consider those approximation schemes that are in agreement with this scenario. Then, even in a simple one-component theory, it becomes natural to introduce two mass scales, say $M_h$ and $m_h$ with $m_h \ll M_h$. This resembles the coexistence of phonons and rotons in superfluid helium-4, which is the non-relativistic analogue of the scalar condensate, and is potentially relevant for the Standard Model. In fact, vacuum stability would depend on $M_h$ and not on $m_h$ and be nearly insensitive to the other parameters of the theory (e.g. the top quark mass). By identifying $m_h=125$ GeV, and with our previous estimate from lattice simulations $M_h= 754 \pm 20 ~\rm{(stat)} \pm 20 ~\rm{(syst)}$ GeV, we thus get in touch with a recent, independent analysis of the ATLAS + CMS data which claims experimental evidence for a scalar resonance around $700$ GeV.

hep-ph↗

arXiv2019

Confronting the Ellipsoidal Universe to the Planck 2018 Data

We compared the Planck 2018 data on the large-scale anisotropies in the cosmic microwave background to the results obtained in the slightly anisotropic ellipsoidal universe. We focused on the quadrupole temperature correlations to better constrain the eccentricity at decoupling and the direction of the symmetry axis. We found that the quadrupole TE and EE temperature correlations in the ellipsoidal universe are still in reasonable agreement with the Planck 2018 data. We suggested that an experimental estimate of the average large-scale polarisation by the Planck Collaboration could confirm or reject the anisotropic universe proposal.

astro-ph.CO↗

arXiv2018

Spatial structure of the color field in the SU(3) flux tube

We report on the chromoelectric and chromomagnetic fields generated by a static quark-antiquark pair at zero temperature in pure gauge SU(3). From the spatial structure of chromoelectric field we extract its nonperturbative part and discuss its properties.

hep-lat↗

arXiv2018

Evidence of the true Higgs boson $H_T$ at the LHC Run 2

The aim of the present note is to compare the recent LHC data at $\sqrt{s} =13 \,TeV$ with our previous theoretical proposal that the true Higgs boson $H_T$ should be a broad heavy resonance with mass around $750 \, GeV$. We focus on the so-called golden channel $H_T \rightarrow ZZ$ where the pair of Z bosons decay leptonically to $\ell^+ \ell^- \ell^+ \ell^-$, $\ell$ being either an electron or a muon. We use the data collected by the ATLAS and CMS Collaborations at $\sqrt{s} =13 \,TeV$ with an integrated luminosity of $36.1 \, fb^{-1}$ and $77.4 \, fb^{-1}$ respectively. We find that the experimental data from both the LHC Collaborations do display in the golden channel a rather broad resonance structure around $700 \, GeV$ with a sizeable statistical significance. Our theoretical expectations seem to be in fair good agreement with the experimental observations. Combining the data from both the ATLAS and CMS Collaborations we obtain an evidence of the heavy Higgs boson in this channel with an estimated statistical significance of more than five standard deviations.

hep-ph↗

arXiv2017

The $H_T$ Higgs boson at the LHC Run 2

We further elaborate on the proposal that the Higgs boson should be a broad heavy resonance, referred to as true Higgs $H_T$, with mass around $750 \, GeV$. We stress once again that within the Standard Model the true Higgs is the unique possibility to implement the spontaneous symmetry breaking of the local gauge symmetry by elementary, relativistic and strictly local scalar fields. We discuss the most relevant decay modes of the $H_T$ boson and estimate they partial decay widths and branching ratios. We discuss briefly the experimental signatures of the $H_T$ Higgs boson and compare with the recent available LHC data at $\sqrt{s} =13 \,TeV$. We find that the coupling of the $H_T$ Higgs boson to fermions is strongly suppressed. We also compare our theoretical expectations in the so-called golden channel to the data collected by the ATLAS and CMS Collaborations at $\sqrt{s} =13 \,TeV$ with an integrated luminosity of $36.1 \, fb^{-1}$ and $35.9 \, fb^{-1}$ respectively. We find that our theoretical expectations are in fair good agreement with the experimental observations. Combining the data from both the LHC Collaborations we obtain an evidence of the heavy Higgs boson in this channel with an estimated statistical significance of more than three standard deviations. Finally, we argue that, if the signal is real, by the end of the Run 2 both the LHC experiments will reach in the golden channel a statistical significance of about five standard deviations.

hep-ph↗