Statut  Confirmé 
Série  FORUMENS 
Domaines  condmat.statmech 
Date  Mercredi 29 Juin 2022 
Heure  12:00 
Institut  LPENS 
Salle  Conf IV 
Nom de l'orateur  Gazit 
Prenom de l'orateur  Snir 
Addresse email de l'orateur  
Institution de l'orateur  Racah Institute of Physics 
Titre  Unconventional criticality and Fermisurface reconstruction without symmetry breaking in a simple lattice model of gauge and matter fields 
Résumé  Gauge theories play a central role in the theoretical description of unconventional phases of matter that go beyond the standard paradigms of quantum statistical mechanics. While in highenergy physics, gauge fields correspond to fundamental particles, in condensed matter theory they are typically emergent and are invoked as an effective description of the lowenergy degrees of freedom. Notable examples include spinliquids, doped Mott insulators, and the fractional Hall effect, among others. In my talk, I will present a signproblem free quantum Monte Carlo study of a lattice model hosting 'orthogonal' fermions coupled to an IsingHiggs gauge theory. Our model provides a simple yet highly nontrivial example of electron fractionalization, which, crucially, remains numerically tractable. We uncover a particularly rich phase diagram arising from strong correlations between gauge and matter fields. In particular, we find that in the background of piflux lattice an orthogonal semimetal (OSM) forms with gapless Dirac fermion excitations. With the tuning of parameters, the OSM undergoes a confinement transition, in which symmetry breaking and confinement are coincident. We construct a fieldtheoretical description of the transition involving condensation of a matrix Higgs field. The critical theory is predicted to sustain emergent and enlarged local (gauge) and global symmetries. We provide numerical evidence supporting this prediction. We also find that the physical (gaugeneutral) spectral function in the OSM phase comprises four fermion pockets, which smoothly evolve to a 'large' Fermi surface upon approach to a Fermi liquid phase. The reconstruction of the Fermi surface does not involve any form of translational symmetry breaking, in violation of the Luttinger sum rule. 
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