In the context of the Swampland program, the Distance Conjecture predicts an infinite tower of states becoming massless at infinite distance in moduli spaces of string compactifications. This is widely believed to be a general feature of quantum gravity, but it is difficult to prove in full generality. On the other hand, the moduli spaces of maximally and half-maximally supersymmetric theory...

Since their discovery in the 90’s, multiple string dualities have been discovered, relating seemingly different perturbative and non-perturbative regimes of the space of parameters (or moduli space), in such a way that in its asymptotic regions one is usually able to work in some duality frame with perturbative control (e.g. large volume and small string coupling). On the other hand, over the...

We study limits of vanishing Yukawa couplings in Quantum Gravity, using as a laboratory type IIA orientifolds. We show that in the limit Y → 0 there are some towers (dubbed gonions) that become asymptotically massless, while at the same time, the kinetic term of some chiral fields becomes singular. For limits parametrised by a large complex structure saxion u, Yukawa couplings have a behavior...

I will discuss supersymmetric AdS_3 flux vacua of massive type-IIA supergravity on G2 orientifolds, focusing on (non) scale separated configurations at large volume and weak-coupling, even highly anisotropic. In addition, inspired by the desire of finding all possible flux choices which give rise to the aforementioned AdS_3 scale-separated configurations, I will discuss some recent...

This study investigates the decay of the Kaluza-Klein vacuum mediated by instanton solutions with singularities. For the Kaluza-Klein vacuum, there exists a non-perturbative decay channel where spacetime is overwhelmed by the bubble of nothing (BoN), which has no degrees of freedom therein. The instanton solution mediating this decay is the BoN instanton, which is the Euclideanized 5D...

There have been numerous recent attempts to elucidate the precise role that the Species Scale plays within quantum gravity, and more generally when trying to characterize the universality class of IR effective field theories (EFT) that descend from a consistent gravitational framework. In this talk we discuss some progress towards the understanding of the Species Scale as the UV cut-off...

We study infinite-distance limits in the moduli space of perturbative string vacua. The remarkable interplay of string dualities seems to determine a highly non-trivial dichotomy, summarized by the emergent string conjecture, by which in some duality frame either internal dimensions decompactify or a unique critical string becomes tensionless. Assuming the existence of light states, we...

Using flat space string amplitudes and recently computed equilibration rates for a thermal gas of highly excited strings, we argue that a Hagedorn phase could have occured in the early Universe with a bath of open strings dominating the energy density. These strings would predominantly decay in Standard Model fields, providing a successful reheating, and would release a gravitational wave...

I will discuss stringy, moduli-driven cosmologies between the end of inflation and the commencement of the Hot Big Bang,a period that can cover half the lifetime of the universe on a logarithmic scale. Compared to the standard cosmology, stringy cosmologies motivate extended kination, tracker and moduli-dominated epochs involving significantly trans-Planckian field excursions. The...

Among various predictions of string compactifications, axions hold a pivotal role, as they provide a unique avenue to tie UV physics to experiments.

Most experimental setups aim to detect a signal using the direct coupling between the axion and the Standard Model. However, string axions do not necessarily need to couple to the Standard Model directly. In this talk I will describe how...

Euclidean wormholes provide concrete examples of non-perturbative gravitational effects leading to a violation of global symmetries. In this talk I will present and analyze a new class of wormhole solutions universally realised in a large set of four-dimensional $\mathcal{N}=1$ axiverse scenarios, and study their low-energy physical implications.

I will present some multi-parametric families of non-supersymmetric EAdS4 flows as well as asymptotically EAdS4 solitons and wormholes, which are constructed within the four-dimensional SO(8) gauged supergravity that describes the compactification of M-theory on S7.

I will also comment on the computation of the on-shell action and gravitational free energy for the regular solutions, the...

In six dimensions, there is an exotic N = (4, 0) supermultiplet that contains only fields of spin ≤ 2, but no graviton, and that on a circle reduces to 5D N = 4 supergravity. It has been proposed that, if suitable interactions exist, the (4, 0) theory might provide a consistent alternative UV completion for N = 4 5D supergravity, realizing a supersymmetric version of asymptotic safety. In this...

The 11-dimensional supergravity is famously the unique maximal supergravity in the maximal possible number of spacetime dimensions. I will discuss the construction of a novel non-relativistic supergravity in 11-d, by taking a limit of the 11-dimensional supergravity. This limit breaks the local Lorentz symmetry from SO(1,10) to SO(1,2) x SO(8) and so is linked to the appearance of membranes in...

The three ten dimensional, non-supersymmetric and non-tachyonic string theories are a great arena for understanding quantum gravity away from the supersymmetric lamppost. However, their full consistency remains unestablished; despite the cancellation of local anomalies, the presence of potential global anomalies poses a threat of becoming fatal pathologies.

After briefly introducing these...

We investigate the four-dimensional WZW terms within the framework of Sp QCD using invertible field theory through bordism theory. We present a novel approach aimed at circumventing both perturbative and non-perturbative gauge anomalies on spacetime manifolds endowed with spin structures. We study both ungauged and gauged WZW terms including the problems of the topological consistency of...

The cobordism conjecture implies that consistent theories of Quantum Gravity must admit the introduction of boundaries. We study the dynamical realization of the cobordism conjecture in type IIB in $AdS_5\times S^5$, using the existing gravity duals of 4d $\mathcal{N} = 4$ SYM with Gaiotto-Witten superconformal boundary conditions (near-horizon limits of D3-branes ending on NS5- and...

In this talk we will present an innovative and alternative way to realise a four-dimensional accelerated expanding cosmology from string theory. This construction is known as the Dark Bubble model and it suggests that an induced four-dimensional universe rides on the boundary (i.e. an expanding $D_{3}$-brane) of a five-dimensional true Anti-de Sitter vacuum that has nucleated within a false...

The tadpole conjecture constrains the number of moduli that can be stabilized with fluxes in F-theory and type IIB flux compactifications. In this talk, I will discuss ongoing work that tests this assertion in non-geometric type IIB flux compactifications with no K\"ahler moduli. In particular, I will restrict to supersymmetric Minkowski vacua in orbifolds of the 1^9 and 2^6 Gepner models....

Among various predictions of string compactifications, axions hold a pivotal role, as they provide a unique avenue to tie UV physics to experiments.

Most experimental setups aim to detect a signal using the direct coupling between the axion and the Standard Model. However, string axions do not necessarily need to couple to the Standard Model directly. In this talk I will describe how...

Since their discovery in the 90’s, multiple string dualities have been discovered, relating seemingly different perturbative and non-perturbative regimes of the space of parameters (or moduli space), in such a way that in its asymptotic regions one is usually able to work in some duality frame with perturbative control (e.g. large volume and small string coupling). On the other hand, over the...

Abstract

We discover a general stringy scaling behavior for

1. All n-point hard string scattering amplitudes (HSSA) and

2. A class of n-point Regge string scattering amplitudes (RSSA)

to all string loop orders.

The number of independent kinematics variables is found to be reduced by dimM.

Based on :

Lai, Lee and Yang, "Stringy scaling of n-point Regge string scattering amplitudes",JHEP...