Equivalence classes and partially broken higher-spin models

• Grant number: 25/25848-0
• Support Opportunities: Scholarships abroad - Research Internship - Master's degree
• Start date: March 10, 2026
• End date: August 09, 2026
• Field of knowledge: Physical Sciences and Mathematics - Physics - Elementary Particle Physics and Fields
• Principal Investigator: Denis Dalmazi
• Grantee: Bruno dos Santos Martins
• Supervisor: Dario Francia
• Host Institution: Faculdade de Engenharia (FEG). Universidade Estadual Paulista (UNESP). Campus de Guaratinguetá. Guaratinguetá , SP, Brazil
• Institution abroad: Università degli Studi Roma Tre, Italy
• Associated to the scholarship: 25/04628-1 - Massless higher-spin particles and the tensionless limit of string theory, BP.MS

Abstract

Our aims are basically twofold. On one hand, we would like to compare field theorydescriptions of reducible models of integer higher spin (HS) particles containing all even(odd) spin modes s, s - 2, s - 4, · · · , 0 (1) for even (odd) spin-s with the so called doublettheory stemming from the tensionless limit of the open string field theory for the lead-ing Regge trajectory. In the field theory description there is some arbitrariness (multi-parametric family of models), while there is no arbitrariness from the string theory side.For the lower spin cases s = 2 and s = 3 we have recently shown that all models inthe physical section of the parameters space are equivalent to each other, which restoresconsistency with the doublet action. Moreover, they are all equivalent to their simplestversion, the so called Maxwell-like model suggested by A. Campoleoni and Prof. DarioFrancia (host supervisor). Our aim here is to generalize those results to the challenginghigher-spin cases s ¿ 4 where there is an even vaster arbitrariness in the models definition.Our second and more auspicious aim regards a new irreducible description of masslessinteger spin-s particles that we have recently suggested. The gauge symmetry is furtherrestricted. Namely, the diffeomorphism parameters are constrained not only by the usualtraceless condition but also by a double-divergence-free condition, allowing for more gen-eral source couplings than the paradigmatic Fronsdal model. We will investigate possibleinteraction vertices for the newly suggested models which is a rather challenging topic inthe HS arena, since there are long standing and severe no-go theorems in the literature.Lastly, we would like to investigate the generalization of the previous aims to mixed-symmetry tensors . This subject has also been investigated by A. Campoleoni and D.Francia and goes beyond the leading Regge trajectory in string theory.