arXiv subjects

Sara Ricossa

Publications and source records attributed to Sara Ricossa.

5 recordsLinked to original sources

arXiv2025

The Rise of Linear Trajectories

In this letter, we consider constraints on the low-energy spectrum of amplitudes with higher-spin exchange. Assuming unitarity, crossing symmetry, and super-convergent high energy behavior, reminiscent of the scattering of spin-1 and spin-2 massless helicity states, we demonstrate that the spectrum that maximizes the leading higher spin couplings of the second and third resonances is consistently given by a linear trajectory. Furthermore, for gravitational theories, the optimal spectrum is the linear trajectory defined by the mass and spin of the graviton and the lightest spin-4 resonance.

hep-th↗

arXiv2025

The EFT Bootstrap at Finite $M_{PL}$

We explore the impact of loop effects on positivity in effective field theories emerging in the infrared from unitary and causal microscopic dynamics. Focusing on massless particles coupled to gravity, we address the treatment of forward-limit divergences from loop discontinuities and establish necessary conditions for maintaining computational control in perturbation theory. While loop effects remain small, ensuring consistency in our approach leads to a significant impact on bounds, even at tree level.

hep-th↗

arXiv2024

Non-Forward UV/IR Relations

We study bounds arising from the analyticity and unitarity of scattering amplitudes in the context of effective field theories with massless particles. We provide an approach that only uses dispersion relations away from the forward limit. This is suitable to derive constraints in the presence of gravity, in a way that is robust with respect to radiative corrections. Our method not only allows us to avoid the Coulomb pole, but also the singularities associated with calculable loop effects, which would otherwise diverge.

hep-th↗

arXiv2024

Positivity Bounds on Massive Vectors

In this paper, we explore positivity bounds for the effective field theory~(EFT) of a single weakly coupled massive vector field. The presence of both mass and spin makes the crossing properties of the amplitudes vastly complicated -- we address this by parametrizing the amplitudes as products of a polarization matrix and a vector of appropriately chosen functions with simpler crossing properties. The resulting framework involves sum rules and null constraints that allows us to constrain any combination of low-energy observables, such as EFT amplitudes. By varying the value of the vector mass over the cutoff scale, some of our bounds asymptote to the bounds obtained in the context of photons and massless scalars. This work paves the way for future applications to e.g. non-abelian massive vectors, glueballs and theories with spin larger than one.

hep-th↗

arXiv2023

Massive Gravity is not Positive

We derive new positivity bounds at finite momentum transfer, assuming a large separation between the mass $m$ of the lightest particle in the effective theory and the mass gap $M$ to new heavy states. Massive gravity parametrically violates these bounds unless the cutoff is within one order of magnitude of the graviton mass $M\lesssim O(10)m$. Non-gravitational effective theories of massive spin-2 particles are similarly bounded.

hep-th↗