arXiv subjects

Tobi Ramella

Publications and source records attributed to Tobi Ramella.

3 recordsLinked to original sources

arXiv2026

Localizing Momentum Waves on Mazes

We examine the proposal and analysis of arXiv:2404.14477 for putting momentum waves on mazes of intersecting M2 and M5 branes by computing a family of simple examples of momentum waves on pure M5 branes. We re-analyze the BPS equations for the near-brane M5-P system with the prescribed supersymmetry structure of the full M2-M5-P system and show that the general linear system obtained in arXiv:2404.14477 captures all of the null momentum waves on the simpler M5-P system. Despite the absence of explicit M2 branes in our examples, we find that the momentum waves still localize on an AdS$_3$ factor of the AdS$_7$ associated with M5 branes, showing that the supersymmetry prescription still reflects the M2-M5-P structure. This momentum localization takes two forms: explicit singular sources and smooth, localized bump functions reflecting ''momentum migration'' that is a feature of other microstate geometries. The simple, physical form of the momentum localization in our examples supports the broader proposal in arXiv:2404.14477 that independent momentum waves can localize at each brane intersection. We suggest further generalizations of momentum waves at brane intersections that could have important implications in holography.

hep-th↗

arXiv2025

The Special Locus

The special locus plays an important role in the construction of the non-BPS microstate geometries known as microstrata. These supergravity solutions are dual to combinations of left-moving and right-moving momentum states in the D1-D5 CFT and because supersymmetry is broken the anomalous dimensions of these states are not protected. This means even the simplest combinations of excitations can create a cascade of frequency dependences through the non-linearities of the supergravity interactions. Solutions on the special locus manage to lock some of these anomalous dimensions together and allow one to construct complete solutions using gauged supergravity in three dimensions. In the dual holographic CFT, the special locus has been shown to correspond to creating a "pure" gas of single particle states, however, in supergravity the special locus remains mysterious especially because it does not seem to be defined by a geometric symmetry. In this paper we reveal the supergravity structure of the special locus, first in three-dimensional supergravity and then in the uplift to six dimensions and IIB supergravity. The key insight is that, in three dimensions, a family of dual vector fields must vanish, and this implies that there are algebraic relations between tensor gauge fields in six and ten dimensions. These insights show how one can generalize the special locus Ansatz to more general mode excitations of six-dimensional supergravity. We also construct the full six-dimensional uplift of the simplest special locus.

hep-th↗

arXiv2025

Properties of scalar partition functions of 2d CFTs

We study the spectrum of scalar primary operators in any two-dimensional conformal field theory. We show that the scalars alone obey a nontrivial crossing equation. This extends previous work that derived a similar equation for Narain conformal field theories. Additionally, we show that at high temperature, the difference between the true scalar partition function and the one predicted from a semiclassical gravity calculation is controlled by: the modular integral of the partition function, the light states of the theory, and an infinite series terms directly related to the nontrivial zeros of the Riemann zeta function. We give several numerical examples and compute their modular integrals.

hep-th↗