arXiv subjects

Alexsandre L. Ferreira Jr

Publications and source records attributed to Alexsandre L. Ferreira Jr.

3 recordsLinked to original sources

arXiv2026

Frame-dependency of the confinement temperature in a strongly-coupled plasma under rotation: a holographic description

Recently, it was demonstrated that the disagreement between lattice calculations and holographic models, regarding rotational effects in the quark-gluon plasma (QGP), occurs due to different choices of reference frames. While a static observer measures a confinement temperature that decreases with rotation, one in a co-rotating frame finds the opposite behavior. Both results are correct, and a comprehension of the frame-dependency of the critical temperature is a significant step in the description of the QGP under rotation. In this article, we generalize this previous holographic result by describing the plasma through the most general Myers-Perry black hole solution. This breaks the spherical symmetry present in the equal angular momentum case, considered before. As a consequence, the local temperature measured by a co-rotating observer has a non-trivial angular dependence: it can decrease, increase or even behave non-monotonically when rotational velocity increases.

hep-th↗

arXiv2026

Unraveling the effect of rotation on the confinement/deconfinement transition of the quark-gluon plasma

There is an apparent contradiction in the current literature about the effect of rotation in the quark-gluon plasma (QGP). While results from lattice QCD predict an increase in the confinement/deconfinement critical temperature, approximated calculations and effective models, including holographic ones, lead to the opposite result. Noncentral heavy ion collisions form QGPs with relativistic rotational velocities. Thereby, a great interest was drawn into the effect of rotation in strongly interacting matter. In this work, we show that the apparent contradiction is associated with the choices of observer considered in each case. We consider a holographic description of a rotating plasma using a Myers-Perry black hole. For a static observer, the result is that the confinement/deconfinement temperature decreases with the angular velocity, while for an observer corotating with the plasma the opposite behavior is found, in agreement with lattice calculations.

hep-th↗

arXiv2025

Bouncing completion of eternal inflation

Using a purely kinematical argument, the Borde-Guth-Vilenkin (BGV) theorem states that any maximal space-time with average positive expansion is geodesically incomplete, hence past eternal inflation would be necessarily singular. Recently, discussions about the broadness of this theorem have been resurfaced by applying it to new models and/or challenging the space-time maximality hypothesis. In the present work, we use reference frames of non co-moving observers and their kinematical properties in order to inquire into the nature of such possible singular beginnings. Using the spatially flat de Sitter (dS) space-time as a laboratory, this approach allows us to exhaust all possibilities bounded by the BGV theorem in the case of general spatially flat Friedmann-Lema\^ıtre-Robertson-Walker (FLRW) geometries. We show that either there exists a scalar or parallelly propagated curvature singularity, or the space-time must be past asymptotically dS (with a definite non-zero limit of the Hubble parameter when the scale factor becomes null, hence excluding certain cyclic models) in order to be extensible. We are able to present this local extension without violating the null energy condition, and we show that this extension must contain a bounce. This is a mathematical result based on purely kinematical arguments and intuition. The possible physical realization of such extensions are also discussed. As a side product, we present a new chart that covers all de Sitter space-time.

gr-qc↗