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Search: authors:"Raffaele Savelli"

10 papers found.
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Compact T-branes

We analyse global aspects of 7-brane backgrounds with a non-commuting profile for their worldvolume scalars, also known as T-branes. In particular, we consider configurations with no poles and globally well-defined over a compact Kähler surface. We find that such T-branes cannot be constructed on surfaces of positive or vanishing Ricci curvature. For the existing T-branes, we...

T-branes and matrix models

We find that the equations describing T-branes with constant worldvolume fields are identical to the equations found by Banks, Seiberg and Shenker twenty years ago to describe longitudinal five-branes in the BFSS matrix model. Besides giving new ways to construct T-brane solutions, this connection also helps elucidate the physics of T-branes in the regime of parameters where...

Discrete anomalies in supergravity and consistency of string backgrounds

We examine SL(2, ℤ) anomalies in ten and eight-dimensional supergravities, the induced local counterterms and their realization in string theory. Composite connections play an important rôle in the cancellation mechanism. At the same time their global properties lead to novel non-trivial consistency constraints on compactifications.

T-branes as branes within branes

Bound states of 7-branes known as ‘T-branes’ have properties that defy usual geometric intuition. For instance, the gauge group of n coincident branes may not be U(n). More surprisingly, matter may show up at unexpected loci, such as points. By analyzing T-branes of perturbative type IIB string theory in the tachyon condensation picture we gain the following insights: in a large...

F-theory on singular spaces

We propose a framework for treating F-theory directly, without resolving or deforming its singularities. This allows us to explore new sectors of gauge theories, including exotic bound states such as T-branes, in a global context. We use the mathematical framework known as Eisenbud’s matrix factorizations for hypersurface singularities. We display the usefulness of this technique...

There and back again: a T-brane’s tale

T-branes are supersymmetric configurations described by multiple Dp-branes with worldvolume flux and non-commuting vacuum expectation values for two of the worldvolume scalars. When these values are much larger than the string scale this description breaks down. We show that in this regime the correct description of T-branes is in terms of a single Dp-brane, whose worldvolume...

T-branes through 3d mirror symmetry

T-branes are exotic bound states of D-branes, characterized by mutually non-commuting vacuum expectation values for the worldvolume scalars. The M/F-theory geometry lifting D6/D7-brane configurations is blind to the T-brane data. In this paper, we make this data manifest, by probing the geometry with an M2-brane. We find that the effect of a T-brane is to deform the membrane...

F-theory at order α′ 3

We study the effective physics of F-theory at order α ′ 3 in derivative expansion. We show that the ten-dimensional type IIB eight-derivative couplings involving the graviton and the axio-dilaton naturally descend from pure gravity in twelve dimensions. Upon compactification on elliptically fibered Calabi-Yau fourfolds, the non-trivial vacuum profile for the axio-dilaton leads to...

On flux quantization in F-theory II: unitary and symplectic gauge groups

We study the quantization of the M-theory G-flux on elliptically fibered Calabi-Yau fourfolds with singularities giving rise to unitary and symplectic gauge groups. We seek and find its relation to the Freed-Witten quantization of worldvolume fluxes on 7-branes in type IIB orientifold compactifications on Calabi-Yau threefolds. By explicitly constructing the appropriate four...

On quantum corrected Kähler potentials in F-theory

We work out the exact in g s and perturbatively exact in α′ result for the vector multiplet moduli Kähler potential in a specific \( \mathcal{N} \) = 2 compactification of F-theory. The well-known α ′3 correction is absent, but there is a rich structure of corrections at all even orders in α ′ . Moreover, each of these orders independently displays an SL(2, \( \mathbb{Z...