Gauge fields from Strings: Novel tools for longstanding problems

• Applicant: Professorin Dr. Valentina Forini
• Subject Area: Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields
• Term: from 2011 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 202347165

• Final Report Year: 2019

Final Report Abstract

Solving a non-trivial four-dimensional gauge theory is a daunting task, which for the largest part of our program we have attacked trying to solve the two-dimensional string model which is its dual according to the gauge/gravity correspondence. Here we have developed new tools for the analysis of string sigma-models relevant in the AdS/CFT correspondence. At the perturbative level, we have initiated the use of unitarity methods for the evaluation of scattering amplitudes – so successfully used in the context of four- and threedimensional gauge theories – in a very general two-dimensional setting, in the relativistic and non-relativistic case. Other relevant steps in the understanding of the detailed structure of sigma-model perturbation theory have been done by solving exactly the spectral problem for a system of coupled fluctuations over a relevant world-sheet solution, explaining the role of the background geometry in the fermionic sector of string fluctuations, and clarifying (the full solution is work in progress) the dilemma of reconciling the prediction of supersymmetric localization with the sigma-model corrections to string solutions dual to supersymmetric Wilson loops. Furthermore, we have explored the string side of lower dimensional versions of the AdS/CFT correspondence in several ways. They include perturbative calculations in AdS4 × CP 3 backgrounds up to two-loop order, the study of integrable backgrounds based on AdS2 and AdS3 geometries supported by various fluxes, and the investigation of potential string models in backgrounds with q-deformed symmetries. An important part of our innovative results has been the rigorous implementation of lattice quantum field theory techniques for the study of string world-sheet models. This study establishes a new sector in numerical holography, suggesting this “two-dimensional way” as a potentially efficient method to test the string/gauge correspondence also at finite coupling. In a separate sub-project, we have initiated the study of generalized cross-sections in N = 4 super Yang-Mills theory with a first analysis of the deep inelastic scattering in this setup. Together with the two-loop extension of this work, the generalization to further cross-sections should shed light on the universality of the formal features so far observed and of their relation, via OPE, to three-point correlation functions. One notable feature of the whole project has been the planned - and effectively achieved - cross-fertilization of methods used. Reflecting this interdisciplinary nature, our results have received the attention of different communities within the area of theoretical physics. We have received as awards: Italian Physical Society 2015 Prize “Giuliano Preparata” for a young graduate student (Lorenzo Bianchi), Carl-Ramsauer-Preis 2016 of the Berlin Physical Society for a PhD Thesis (Lorenzo Bianchi), Lisa Meitner Prize 2015 of the Friends of the Institute for Physics at Humboldt University Berlin for the category “Outstanding Master Thesis” (Alexander Jahn); GATIS prize for the best talk at the conference IGST 2016, Berlin (Valentina Forini); two works were selected for inclusion in the Journal of Physics A - Highlights of 2013 and 2015 collections.

Publications

• “Generalized cusp in AdS4 × CP 3 and more one-loop results from semiclassical strings”, J.Phys. A46 (2013) 115402
  V. Forini, V. Giangreco M. Puletti, O. Ohlsson Sax
  
• “Two-dimensional S-matrices from unitarity cuts”, JHEP, 1307(2013)088
  L. Bianchi, V. Forini and B. Hoare
  
• “Two-loop cusp anomaly in ABJM at strong coupling”, JHEP 1410 (2014) 013
  L. Bianchi, M. S. Bianchi, A. Brés, V. Forini, E. Vescovi
  
• “One-loop spectroscopy of semiclassically quantized strings: bosonic sector”, J.Phys. A48 (2015) 8, 085401
  V. Forini, V. Giangreco M. Puletti, M. Pawellek, E. Vescovi
  
• “Remarks on the geometrical properties of semiclassically quantized strings,”, J. Phys. A 48, no. 47, 475401 (2015)
  V. Forini, V. G. M. Puletti, L. Griguolo, D. Seminara and E. Vescovi
  
• “Remarks on the geometrical properties of semiclassically quantized strings”, J.Phys. A48 (2015) 47, 475401
  V. Forini, V. Giangreco M. Puletti, L. Griguolo, D. Seminara, E. Vescovi
  
• “Green-Schwarz string on the lattice”, JHEP 1607 (2016) 014
  V. Forini, L. Bianchi, M. S. Bianchi, B. Leder and E. Vescovi
  
• “Precision calculation of 1/4-BPS Wilson loops in AdS5 × S 5 ”, JHEP 1602 (2016) 105
  V. Forini, V. Giangreco M. Puletti, L. Griguolo, D. Seminara, E. Vescovi
  
• “Strings on the lattice and AdS/CFT” PoS LATTICE 2016, 206 (2016)
  V. Forini, L. Bianchi, B. Leder, P. Toepfer and E. Vescovi
  
• “Perturbative computation of string one-loop corrections to Wilson loop minimal surfaces in AdS5 × S5” JHEP 1703, 003 (2017)
  V. Forini, A. A. Tseytlin and E. Vescovi