Antonino Marciano

GENERALIZING THE NOETHER THEOREM FOR HOPF-ALGEBRA SPACETIME SYMMETRIES

Over these past few years several quantum-gravity research groups have been exploring the possibility that in some Planck-scale nonclassical descriptions of spacetime one or another form of nonclassical spacetime symmetries might arise. One of the most studied scenarios is based on the use of Hopf algebras, but previous attempts were not successful in deriving constructively the properties of the conserved charges one would like to obtain from the Hopf structure, and this in turn did not allow a crisp physical characterization of the new concept of spacetime symmetry. Working within the example of κ-Minkowski noncommutative spacetime, known to be particularly troublesome from this perspective, we observe that these past failures in the search of the charges originated from not recognizing the crucial role that the noncommutative transformation parameters play in the symmetry analysis. We show that, if indeed one introduces appropriate noncommutative transformation parameters, all the steps of the Noether analysis can be easily performed, obtaining an explicit formula for the charges carried by fields that are solutions of the equation of motion.

Inflation in (Super-)renormalizable Gravity

We investigate a (super-)renormalizable and ghost-free theory of gravity, showing that under a natural (exponential) ansatz of the form factor and a suitable truncation it can give rise to the Starobinsky inflationary theory in cosmological frameworks, and thus offering a theoretical justification of its origin. We study the corresponding inflationary evolution and we examine the generation of curvature perturbations, adapting the

Noether analysis of the twisted Hopf symmetries of canonical noncommutative spacetimes

f(R)

Chern-Simons inflation and baryogenesis

-like equations in a symmetry-reduced Friedmann-Lema\^{\i}tre-Robertson-Walker metric. Furthermore, we analyze how the ultraviolet regime of a simply renormalizable and unitary theory of gravity is also compatible with the Starobinsky action, and hence we show that such a theory could account for an inflationary phase of the Universe in the ultraviolet regime.

Gravitational origin of the weak interaction's chirality

We study the twisted-Hopf-algebra symmetries of observer-independent canonical spacetime noncommutativity, for which the commutators of the spacetime coordinates take the form [x̂, x̂ ] = iθ with observer-independent (and coordinate-independent) θ . We find that it is necessary to introduce nontrivial commutators between transformation parameters and spacetime coordinates, and that the form of these commutators implies that all symmetry transformations must include a translation component. We show that with our noncommutative transformation parameters the Noether analysis of the symmetries is straightforward, and we compare our canonical-noncommutativity results with the structure of the conserved charges and the “no-pure-boost” requirement derived in a previous study of κ-Minkowski noncommutativity. We also verify that, while at intermediate stages of the analysis we do find terms that depend on the ordering convention adopted in setting up the Weyl map, the final result for the conserved charges is reassuringly independent of the choice of Weyl map and (the corresponding choice of) star product. ∗Supported by EU Marie Curie fellowship EIF-025947-QGNC

Fermi-bounce cosmology and scale-invariant power spectrum

We present a model of inflation based on the interaction between a homogeneous and isotropic configuration of a U(1) gauge field and fermionic charge density

Spherically symmetric sector of self dual Ashtekar gravity coupled to matter: Anomaly-free algebra of constraints with holonomy corrections

\mathcal{J}_{0}

Singularity avoidance in classical gravity from four-fermion interaction

. The regulated fermionic charge density is generated from a Bunch-Davies vacuum state using the methods of Koksma and Prokopec \cite{Koksma:2009tc}, and is found to redshift as

ON THE 5D DIFFERENTIAL CALCULUS AND TRANSLATION TRANSFORMATIONS IN 4D κ-MINKOWSKI NONCOMMUTATIVE SPACE–TIME

1/a(\eta)

Coherent states for FLRW space-times in loop quantum gravity

. The time-like component of gauge field is sourced by the fermionic charge leading to a growth in the gauge field