Lattice investigation of SU(2) gauged custodial two-Higgs-doublet model at weak quartic couplings
C.-J. David Lin1,2*, Guilherme Catumba3,4, Atsuki Hiraguchi1,5, Wei-Shu Hou6, Karl Jansen7, Ying-Jer Kao6,8, Alberto Ramos4, Mugdha Sarkar1,6
1Institute of Physics, National Yang Ming Chiao Tung University, Hsinchu, Taiwan
2Centre for High Energy Physics, Chung-Yuan Christian University, Taoyuan, Taiwan
3Department of Physics, University of Milano-Bicocca & INFN Milano–Bicocca, Milano, Italy
4Instituto de Fisica Corpuscular, CSIC-Universitat de Valencia, Valencia, Spain
5CCSE, Japan Atomic Energy Agency, Chiba, Japan
6Department of Physics, National Taiwan University, Taipei, Taiwan
7Deutsches Elektronen-Synchrotron DESY, Zeuthen, Germany
8Centre for Theoretical Physics and Centre for Quantum Science and Technology, National Taiwan University, Taipei, Taiwan
* Presenter:C.-J. David Lin, email:dlin@nycu.edu.tw
The SU(2)−gauged custodial two-Higgs-doublet model, which shares the same global-symmetry properties with the standard model, is studied non-perturbatively on the lattice. The additional Higgs doublet enlarges the scalar spectrum and opens the possibility for spontaneous breaking of the global symmetry. In this work we start by showing the occurrence of spontaneous breaking of the custodial symmetry in a region of the parameter space of the model. Following this, both the spectrum and the running of the gauge coupling are examined at weak quartic couplings in the presence of the custodial symmetry. The calculations are performed with energy cutoffs ranging from 300 to 600 GeV on a line of constant standard model physics, obtained by tuning bare couplings to fix the ratio between the masses of the Higgs and the W bosons, as well as the value of the renormalised gauge coupling at the scale of the W boson mass. The realisable masses for the additional scalar states are explored. For the choice of bare quartic couplings in this work, the estimated lower bound of these masses is found to be well below the W boson mass, and independent of the cutoff. We also study the finite temperature electroweak transition along this line of constant standard model physics, revealing properties of a smooth crossover behaviour.


Keywords: Lattice field theory, Two-Higgs-doublet model, Electroweak phase transition