Analytical Green’s functions for continuum spectra Megías Fernández, Eugenio Quirós, Mariano Phenomenology of Field Theories in Higher Dimensions Phenomenology of Large extra dimensions We would like to thank A. Carmona, M. Perez-Victoria and L.L. Salcedo for fruitful discussions. The authors thank the ICTP South American Institute for Fundamental Research (SAIFR), Sao Paulo, Brazil, and its Program on Particle Physics, September 30-November 30, 2019, where part of this work was done, for hospitality. The work of EM is supported by the Spanish MINEICO under Grants FIS2017-85053-C2-1-P and PID2020-114767GB-I00, by the FEDER/Junta de Andalucia-Consejeria de Economia y Conocimiento 2014-2020 Operational Programme under Grant A-FQM-178-UGR18, by Junta de Andalucia under Grant FQM-225, and by the Consejeria de Conocimiento, Investigacion y Universidad of the Junta de Andalucia and European Regional Development Fund (ERDF) under Grant SOMM17/6105/UGR. The research of EM is also supported by the Ramon y Cajal Program of the Spanish MINEICO under Grant RYC-2016-20678. The work of MQ is partly supported by Spanish MINEICO under Grant FPA2017-88915-P, by the Catalan Government under Grant 2017SGR1069, and by Severo Ochoa Excellence Program of MINEICO under Grant SEV-2016-0588. IFAE is partially funded by the CERCA program of the Generalitat de Catalunya. Green's functions with continuum spectra are a way of avoiding the strong bounds on new physics from the absence of new narrow resonances in experimental data. We model such a situation with a five-dimensional model with two branes along the extra dimension z, the ultraviolet (UV) and the infrared (IR) one, such that the metric between the UV and the IR brane is AdS(5), thus solving the hierarchy problem, and beyond the IR brane the metric is that of a linear dilaton model, which extends to z -> infinity. This simplified metric, which can be considered as an approximation of a more complicated (and smooth) one, leads to analytical Green's functions (with a mass gap m(g) similar to TeV and a continuum for s > m(g)(2)) which could then be easily incorporated in the experimental codes. The theory contains Standard Model gauge bosons in the bulk with Neumann boundary conditions in the UV brane. To cope with electroweak observables the theory is also endowed with an extra custodial gauge symmetry in the bulk, with gauge bosons with Dirichlet boundary conditions in the UV brane, and without zero (massless) modes. All Green's functions have analytical expressions and exhibit poles in the second Riemann sheet of the complex plane at s = M-n(2) - iM(n)Gamma(n), denoting a discrete (infinite) set of broad resonances with masses (M-n) and widths (Gamma(n)). For gauge bosons with Neumann or Dirichlet boundary conditions, the masses and widths of resonances satisfy the (approximate) equation s = -4m(g)(2) W-n(2)[+/-(1 + i)/4], where Wn is the n-th branch of the Lambert function. 2021-10-19T08:54:14Z 2021-10-19T08:54:14Z 2021-09-23 info:eu-repo/semantics/article Megías, E., Quirós, M. Analytical Green’s functions for continuum spectra. J. High Energ. Phys. 2021, 157 (2021). [https://doi.org/10.1007/JHEP09(2021)157] http://hdl.handle.net/10481/70968 10.1007/JHEP09(2021)157 eng http://creativecommons.org/licenses/by/3.0/es/ info:eu-repo/semantics/openAccess Atribución 3.0 España Springer