arXiv subjects

Massimo Cerdonio

Publications and source records attributed to Massimo Cerdonio.

10 recordsLinked to original sources

arXiv2021

A superfluid He4 version of a test on QG vs CG: feasibility with demonstrated methods

A field, which mediates entanglement between two quantum systems, must be of quantum nature. Attempts to witness this way quantumlike features of the gravitational field with tabletop experiments are actively studied recently, in particular by considering to look at two masses in a superposition in two locations, each in one interferometer. Entanglement intervention is probed when the interferometers are put side by side. If the masses interact only via Newtonian attraction, and still some degree of entanglement is found, than the gravitational field must be quantum like, or at least non-classical. The masses considered are mesoscopic, 10-14 Kg to 10-12 Kg, and in one proposal Mach-Zehnder interferometry is considered. Liquid He4 is superfluid below 2.17 K, and shows macroscopic quantum behaviour, in particular matter interferometry, as in the Superfluid He Quantum Inteference Device - SHeQUID. With its Josephson junctions as slits, the SHeQUID parallels a Mach-Zehnder. In this case the matter quantities involved are macroscopic, 10-8 Kg. We propose and analize the feasibility of a scheme on the lines of the above, where the matter field is given by superfluid He4, and the Mach-Zehnder's are two SHeQUID, put side by side. We find that the proposed experiment is feasible, using only well demonstrated methods and technologies, with no need to extensions beyond the current frontiers.

quant-ph↗

arXiv2019

The H0 tension: did a QCD meV axion emerge?

I discuss the possibility that the difference in the measured Hubble constant Ho between the current, Late, and the z ~1100, Early, epochs is due to the emergence in between of a new particle. I connect that difference with a change in the effective cosmological constant observed by LambdaCDM, which is induced by the energy density of the vacuum of the field of the new particle. Then I try to provide the main characteristics of the particle, boson vs fermion and mass, using the measured change in Ho and a Lorentz invariant regularization of the energy density of vacuum, which relates it to such characteristics. The result indicates that a boson of mass in the range of few meV emerged. A QCD post-inflation cosmological axion in this mass range is allowed by recent analysis and its detection may be attempted according to recent experimental proposals.

gr-qc↗

arXiv2019

About the measure of the bare cosmological constant

I try to revive, and possibly reconcile, a debate started a few years ago, about the relative roles of a bare cosmological constant and of a vacuum energy, by taking the attitude to try to get the most from the physics now available as established. I notice that the bare cosmological constant of the Einstein equations, which is there ever since GR emerged, is actually constrained (if not measured) indirectly from the effective cosmological constant observed now, as given by Precision Cosmology and from the cumulative vacuum contribution of Standard Model particles, when this is evaluated using the well-established physics of Quantum Field Theory. Therefore the fine tuning, implied by the compensation to a small positive value of the two large contributions, could be seen as offered by Nature, which provides one more fundamental constant, the bare Lambda. The possibility is then discussed of constraining (measuring) directly such a bare cosmological constant by the features of primordial gravitational wave signals. A hint is briefly discussed for a possible bare Lambda inflation process.

gr-qc↗

arXiv2017

Comment to "How does Casimir energy fall? IV. Gravitational interaction of regularized quantum vacuum energy" by K A Milton et al., Phys Rev D 89 064027 (2014)

The Paper actually concerns a toy model, not physical Casimir cavities made of conducting plates, but the results are taken implicitly to apply in general. We question on general physical grounds one basic assumption and the results of a renormalization procedure. Then, for physical systems, i) considering condensed matter theory/experiments, we find strong evidence against the conclusive claims concerning a putative and dominating surface energy present individually on the plates, and ii) we propose two experiments with physical Casimir cavities to show in detail that the results of the renormalization in this case look somewhat paradoxical. In any case the proposed experiments appear to be feasible and thus it could be tested if the putative self-energies of the plates are indeed there in a physical Casimir cavity, or if the toy model of the Paper has by contrast no connection with physical reality. However at the moment the authors are not legitimate to issue as conclusive claims statements like- refute the claim sometimes attributed to Feynman that virtual photons do not gravitate -

gr-qc↗

arXiv2017

Quantized vortex rings in superfluid He4 and Light Dark Matter

The possibility is considered that, after nuclear recoil caused by elastic scattering with Light Dark Matter, atoms in superfluid He4 may create quantized vortex rings, which can thereafter be detected. The concept for sort of telescope for LDM is presented, which would be sensitive to its motion through the Galactic LDM wind. A demonstrator is proposed, which makes use of thermal neutrons.

hep-ph↗

arXiv2016

Search for light scalar Dark Matter candidate with AURIGA detector

A search for a new scalar field, called moduli, has been performed using the cryogenic resonant-mass AURIGA detector. Predicted by string theory, moduli may provide a significant contribution to the dark matter (DM) component of our universe. If this is the case, the interaction of ordinary matter with the local DM moduli, forming the Galaxy halo, will cause an oscillation of solid bodies with a frequency corresponding to the mass of moduli. In the sensitive band of AURIGA, some $100\,\mathrm{Hz}$ at around $1\,\mathrm{kHz}$, the expected signal, with a $Q=\tfrac{\triangle f}{f}\sim10^{6}$, is a narrow peak, $\triangle f\sim1\,\mathrm{mHz}$. Here the detector strain sensitivity is $h_{s}\sim2\times10^{-21}\,\mathrm{Hz^{-1/2}}$, within a factor of $2$. These numbers translate to upper limits at $95\%\,C.L.$ on the moduli coupling to ordinary matter $d_{e}\lesssim10^{-5}$ around masses $m_ϕ=3.6\cdot10^{-12}\,\mathrm{eV}$, for the standard DM halo model with $ρ_{DM}=0.3\,\mathrm{GeV/cm^{3}}$.

hep-ex↗

arXiv2015

A Casimir cannot cavity fly

The field inside a Casimir cavity has an effective negative mass, which acts as a buoyancy force in a gravitational field. Can this render the total mass of the cavity negative, making it "float" in the vacuum ? Recent theoretical arguments indicate that this is impossible. We provide support to this conclusion discussing a concrete simple model of cavity, with plane parallel metallic plates kept in mechanical equilibrium by a spring and placed in a weak gravitational field. We show that basic facts about the structure of matter imply that the total mass of the cavity is always positive. This has implications for the hypothetical relation between vacuum energy and cosmological constant.

gr-qc↗

arXiv2010

Effects of Interplanetary Dust on the LISA drag-free Constellation

The analysis of non-radiative sources of static or time-dependent gravitational fields in the Solar System is crucial to accurately estimate the free-fall orbits of the LISA space mission. In particular, we take into account the gravitational effects of Interplanetary Dust (ID) on the spacecraft trajectories. The perturbing gravitational field has been calculated for some ID density distributions that fit the observed zodiacal light. Then we integrated the Gauss planetary equations to get the deviations from the LISA keplerian orbits around the Sun. This analysis can be eventually extended to Local Dark Matter (LDM), as gravitational fields are expected to be similar for ID and LDM distributions. Under some strong assumptions on the displacement noise at very low frequency, the Doppler data collected during the whole LISA mission could provide upper limits on ID and LDM densities.

gr-qc↗

arXiv2006

Principles of wide bandwidth acoustic detectors and the single-mass DUAL detector

We apply the standard theory of the elastic body to obtain a set of equations describing the behavior of an acoustic Gravitational Wave detector, fully taking into account the 3-dimensional properties of the mass, the readout and the signal. We show that the advantages given by a Dual detector made by two nested oscillators can also be obtained by monitoring two different acoustic modes of the same oscillator, thus easing the detector realization. We apply these concepts and by means of an optimization process we derive the main figures of such a single-mass Dual detector designed specifically for the frequency interval 2-5kHz. Finally we calculate the SQL sensitivity of this detector.

gr-qc↗

arXiv2002

Fake signals caused by heavy mass motions near a sensitive spherical gravitational wave antenna

This paper analyses in quantitative detail the effect caused by a moving mass on a spherical gravitational wave detector. This applies to situations where heavy traffic or similar disturbances happen near the GW antenna. Such disturbances result in quadrupole tidal stresses in the antenna mass, and they therefore precisely fake a real gravitational signal. The study shows that there always are characteristic frequencies, depending on the motion of the external masses, at which the fake signals are most intense. It however appears that, even at those frequencies, fake signals should be orders of magnitude below the sensitivity curve of an optimised detector, in likely realistic situations.

gr-qc↗