New physics from lattice simulations of strongly interacting gauge theories
Final Report Abstract
The aim of this project is a better understanding of strongly interacting gauge theories of beyond the Standard Model of particle physics and in this way to gain insights in the fundamental laws and building blocks of nature. The Standard Model describes all known fundamental particles and their interactions. Despite its success, the Standard Model appears to be incomplete. According to astronomical observations, it does not describe most of the matter in the universe, and there are conceptual shortcomings like the Hierarchy Problem or the missing inclusion of gravity. New strongly interacting theories have been derived as an extension of the Standard Model and to resolve its shortcomings. In this project we have investigated supersymmetric gauge theories, which are an essential part of supersymmetric extensions of the Standard Model. The second investigated approach is based on composite Higgs theories, in which the Higgs field emerges from a new strongly interacting theory. Insights into the relevant non-perturbative regime of these theories are only possible using numerical simulations on a space-time lattice, which require high performance computing facilities. We have investigated for the first time supersymmetric Yang-Mills theory with the gauge group SU(3), the same gauge group as quantum chromodynamics (QCD). We have determined the spectrum of lightest particles for this theory. It is remarkable that the supersymmetry of the fundamental theory is reflected in the non-perturbative bound state spectrum at low energies. We have investigated further properties of supersymmetric Yang-Mills theory. One particular interesting finding is the coincidence of chiral and deconfinement transitions. We have also been able to determine the gluino condensate for the first time with Wilson fermions. In addition, we have extended our studies towards supersymmetric QCD and investigations of gauge/gravity duality. These will be continued in the following projects. Candidates for technicolor and composite Higgs extensions of the Standard Model are severely constrained by experimental data. It has been conjectured that only theories quite different from standard QCD could fulfill these requirements. This leads to the general question in what kind of ways strong interactions can be realized, in particular regarding the location of a conformal window containing theories that become scale invariant due to an infrared fixed point. We have investigated the conformal window for gauge theories with a different number of fermions in the adjoint representation and determined their properties with recent methods like the Yang-Mills gradient flow. In addition, we have done the first investigations of a gauge theory coupled to fermions in fundamental and adjoint representation. The results of these investigations provide new insights regarding the relevance of Standard Model extensions, and they are also interesting for general theoretical considerations. The non-perturbative dynamics of strong interactions is so far inaccessible for analytical methods. The considerations of new strongly interacting theories beyond the Standard Model provides also a new perspective for the analytical understanding of strong interactions. The project investigates special gauge theories on a compactified space-time. This allows a connection between an analytically accessible confined regime and the full dynamics of the four dimensional strongly interacting gauge theory. We have done detailed studies of the confined regime at a small radius and tested conjectures about a continuity towards the decompactification limit. We have also studied how numerical results and analytic predictions can be connected.
Publications
- Adiabatic continuity and confinement in supersymmetric Yang-Mills theory on the lattice, JHEP 1811 (2018) 092
G. Bergner, S. Piemonte, M. Ünsal
(See online at https://doi.org/10.1007/JHEP11(2018)092) - Analysis of Ward identities in supersymmetric Yang–Mills theory, Eur. Phys. J. C 78 (2018) no.5, 404
S. Ali, H. Gerber, I. Montvay, G. Münster, S. Piemonte, P. Scior, G. Bergner
(See online at https://doi.org/10.1140/epjc/s10052-018-5887-9) - Montvay and S. Piemonte, Low energy properties of SU(2) gauge theory with Nf = 3/2 flavours of adjoint fermions, JHEP 1801 (2018) 119
G. Bergner, P. Giudice, G. Münster, P. Scior, I.
(See online at https://doi.org/10.1007/JHEP01(2018)119) - The light bound states of N = 1 supersymmetric SU(3) Yang-Mills theory on the lattice, JHEP 1803, 113 (2018)
S. Ali, G. Bergner, H. Gerber, P. Giudice, I. Montvay, G. Münster, S. Piemonte, P. Scior
(See online at https://doi.org/10.1007/JHEP03(2018)113) - The running coupling from gluon and ghost propagators in the Landau gauge: Yang-Mills theories with adjoint fermions, Phys. Rev. D 97 (2018) no.7, 074510
G. Bergner, S. Piemonte
(See online at https://doi.org/10.1103/PhysRevD.97.074510) - Numerical results for the lightest bound states in N = 1 supersymmetric SU(3) Yang-Mills theory, Phys. Rev. Lett. 122, no. 22, 221601 (2019)
S. Ali, G. Bergner, H. Gerber, I. Montvay, G. Münster, S. Piemonte, P. Scior
(See online at https://doi.org/10.1103/PhysRevLett.122.221601) - Study of center and chiral symmetry realization in thermal N = 1 super Yang-Mills theory using the gradient flow, Phys. Rev. D 100 (2019) no.7, 074501
G. Bergner, C. López and S. Piemonte
(See online at https://doi.org/10.1103/PhysRevD.100.074501) - Variational analysis of low-lying states in supersymmetric Yang-Mills theory, JHEP 1904, 150 (2019)
S. Ali, G. Bergner, H. Gerber, S. Kuberski, I. Montvay, G. Münster, S. Piemonte, P. Scior
(See online at https://doi.org/10.1007/JHEP04(2019)150) - Continuum extrapolation of Ward identities in N = 1 supersymmetric SU(3) Yang-Mills theory, Eur. Phys. J. C 80 (2020) no.6, 548
S. Ali, G. Bergner, H. Gerber, I. Montvay, G. Münster, S. Piemonte, P. Scior
(See online at https://doi.org/10.1051/epjconf/201817508003) - Thermal phase transition in Yang-Mills matrix model, JHEP 01 (2020), 053
G. Bergner, N. Bodendorfer, M. Hanada, E. Rinaldi, A. Schäfer, P. Vranas
(See online at https://doi.org/10.1007/JHEP01(2020)053)
