Higher-spin particles at high-energy colliders

Abstract

Using an effective field theory approach for higher-spin fields, we derive the interactions of colour singlet and electrically neutral particles with a spin higher than unity, concentrating on the spin-3/2, spin-2, spin-5/2 and spin-3 cases. We compute the decay rates and production cross sections in the main channels for spin-3/2 and spin-2 states at both electron-positron and hadron colliders, and identify the most promising novel experimental signatures for discovering such particles at the LHC. The discussion is qualitatively extended to the spin-5/2 and spin-3 cases. Higher-spin particles exhibit a rich phenomenology and have signatures that often resemble the ones of supersymmetric and extra-dimensional theories. To enable further studies of higher-spin particles at collider and beyond, we collect the relevant Feynman rules and other technical details.

Ghost and Tachyon Free Propagation up to spin-3 in Lorentz Invariant Field Theories

“…While attempts to emancipate particle phenomenology from local fields are an intriguing line of past and present research [34][35][36][37], their use is still mainstream when it comes to provide scattering amplitudes at relativistic energies. The capital issue of this approach is represented by the clash between the field components and the particle which they describe.…”

An effective field theory of the Delta-resonance

“…We describe the system of photons, pions, nucleons and ∆-baryons at low energies through a Lorentz-invariant EFT in which the ∆ is a field in the (3/2, 0)⊕(0, 3/2) representation of the Lorentz group, using the multi-spinor formalism introduced in Refs. [74][75][76]. From here on, we will refer to this description of a spin-3/2 field as the multi-spinor framework (MSF).…”

“…On the other hand, the effective field theory (EFT) re-formulation of Weinberg's original idea using multispinor representations [74] has turned out to be simple and practical, providing a consistent description of generic massive higher-spin particle interactions below some cut-off scale Λ. This EFT has successfully been used to study generic higher-spin dark matter [74], production and decays of higher-spin particles at colliders [75] and higher-spin induced contributions to the anomalous lepton moments [76].…”

Gauging the Higher-Spin-Like Symmetries by the Moyal Product. II

“…Higher Spin (HS) particles are a natural prediction of string theory, and therefore they can be expected to play quite a crucial role whenever we attempt to include the Standard Model in a consistent theory of Quantum Gravity. In recent years, stopping a historical neglect mainly due to the difficulty of describing them by a straightforward generalization of lower spin cases and their observational elusiveness, they started playing an increasingly relevant role in phenomenological studies of both collider physics and cosmology (see e.g., [1][2][3][4] and references therein). On the theoretical side, the onset of HS degrees of freedom has been put in a close connection to the avoidance of causality problems in graviton scattering amplitudes [5,6] and to the good UV behavior of string theory.…”