Talk detail

Participant	Briscese, Fabio
Institution	Southern University of Science and Technology - 1088 Xiuyan BLVD. - Shenzhen - Guandong - China

Session	SF1	Accepted		Order	Time
Talk	Oral abstract	Title	Photon polarization oscillations
Coauthors
Abstract	It has been recently demonstrated that, under the action of light-by-light scattering, light beams show collective behaviors in vacuum. For instance, in the case of two counterpropagating laser beams with specific initial helicity, the polarization of each beam oscillates periodically between the left and right helicity. Furthermore, the amplitudes and the corresponding intensities of each polarization propagate like waves. We discuss the possibility of detecting photon polarization oscillations in astrophysical observations and in laser experiments, testing light-by-light scattering in a physical (strong field) regime complementary to that explored in particle accelerators. This talk is based on the following papers: 1) F. Briscese, Light polarization oscillations induced by photon-photon scattering, PHYSICAL REVIEW A 96, 053801 (2017). 2) F. Briscese, Collective behavior of light in vacuum, PHYSICAL REVIEW A 97, 033803 (2018).
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Session	DM4	Accepted		Order	Time
Talk	Oral abstract	Title	The Schrödinger–Poisson equations as the N-body double of dark matter dynamics at large scales.
Coauthors
Abstract	It has been recently shown that, based on the stochastic quantization introduced by Nelson and on the Calogero conjecture, the dynamics of the classical Newtonian N-body system can be described in terms of the Schrödinger–Poisson equations (SPE) in the large N limit. This is due to the stochastic quantization of the N-body system induced by the random gravitational background produced by the N bodies. We discuss the relevance of this finding in the context of Large Scale Structure (LSS) formation. The advantage of this formulation of SPE is that, according to the Calogero conjecture, the emergent effective Planck constant is expressed in terms of the parameters of the N-body system, while in LSS numerical simulations it is a free parameter adjusted to fit the data. We show that these two approaches are in perfect agreement, which supports the correctness of our results, and the validity of the SPE as numerical double of the N-body simulations of dark matter dynamics at large scales. Moreover, this is the first practical application of the Nelson quantization and of the Calogero conjecture to a realistic physical problem. This talk is based on the following paper: F. Briscese, The Schrödinger–Poisson equations as the large-N limit of the Newtonian N-body system: applications to the large scale dark matter dynamics, Eur. Phys. J. C (2017) 77:623.
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Session	ES1	Accepted		Order	Time
Talk	Oral abstract	Title	Isochronous Spacetimes
Coauthors
Abstract	It has been shown that, given any (translation-invariant, classical) nonrelativistic many-body problem characterized by a Hamiltonian H, it is possible to manufacture another (translation-invariant) many-body problem characterized by a suitably modified Hamiltonian $\tilde{H}$ which features an isochronous time evolution with an arbitrarily assigned period $\tilde{T}$--so that all its solutions are periodic with period $\tilde{T}$--yet mimics exactly the dynamics of the Hamiltonian H over times T; with both $\tilde{T}$ and T arbitrarily assigned, except for the restriction $T < \tilde{T}$. We show how this result is extended to a general relativistic context by enlarging the class of admissible solutions of Einstein’s equations to degenerate metrics. We show how these degenerate isochronous metrics are obtained from a generic spacetime, and we discuss their properties. This talk is based on the following papers: Fabio Briscese and Francesco Calogero, "Isochronous solutions of Einstein.s equations and their Newtonian limit", Int. J. Geom. Meth. Mod. Phys. 15 (2018) 185010; "Isochronous Spacetimes", Acta Appl.Math. 137 (2015) 3-16; "Isochronous Cosmologies", Int. J. Geom. Meth. Mod. Phys. 11 (2014) 1450054.
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Session	QG2	Accepted		Order	Time
Talk	Oral abstract	Title	Formal aspects of nonlocal quantum field theory
Coauthors
Abstract	It has been realized that nonlocality might be a key ingredient for the formulation of a quantum renormalizable theory of gravitation. In facts, nonlocal gravitational models are earning growing interest in the scientific community, since they are super-renormalizable or even finite at quantum level. In this seminar I will discuss some general features of nonlocal field theories. In particular, I will show how Cutkosky rules are generalized to the case of nonlocal theories, so that the perturbative unitarity is easily established. Moreover, I will discuss the problem of causality in nonlocal theories.
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