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SUMMARY:The uses of the SO(5)/SO(2) Stiefel sigma model for the unified Zh
 ang's model
DTSTART;VALUE=DATE-TIME:20260924T075000Z
DTEND;VALUE=DATE-TIME:20260924T081000Z
DTSTAMP;VALUE=DATE-TIME:20260914T043703Z
UID:indico-contribution-549@indico.bitp.kiev.ua
DESCRIPTION:Speakers: Yuliia Lunha (Bogolubov Institute for Theoretical Ph
 ysics)\nWe investigate the critical behavior and phase structure of nonlin
 ear sigma models on real Stiefel manifolds SO(N)/SO(N-k)\, with particular
  focus on the SO(5)/SO(2) model and its relation to the $SO(5)$-based Zhan
 g model of competing antiferromagnetic and superconducting orders. The Sti
 efel model is characterized by two effective interaction coupling constant
 s\, which give rise to a tetracritical regime implying\, in particular\, t
 he appearance of the phase with coexistence of antiferromagnetic and super
 conducting orders. We analyze the scaling behavior and properties of the f
 our phases using both Hamiltonian and Lagrangian formulations. In particul
 ar\, we determine quasiparticle masses and apply these to characterize the
  symmetry breaking in different phases\, including the mixed phase where t
 he two orders coexist. As one of our main results we present the determina
 tion of "transverse" critical exponents for the tetracritical point. These
  exponents complement the previously obtained critical exponents in the (T
 )-direction and provide a more complete characterization of the associated
  universality classes. Note that the transverse critical exponents are obt
 ained for the general class of Stiefel models SO(N)/SO(N-k). We further ex
 amine the electron–hole asymmetry\, which is not intrinsically incorpora
 ted in the Zhang model but emerges naturally in the Stiefel model framewor
 k. For the SO(5)/SO(2) model\, the resulting carrier charge has the physic
 ally relevant sign\, in contrast to the SO(5)/SO(3) Stiefel model which\, 
 in addition\, does not exhibit tetracritical behavior. The obtained result
 s establish an important connection between the critical structure (and ph
 ases) of Stiefel sigma models and the phenomenology of competing antiferro
 magnetic and superconducting orders.\n\nhttps://indico.bitp.kiev.ua/event/
 18/contributions/549/
LOCATION:Bogolyubov Institute for Theoretical Physics Conference Hall
URL:https://indico.bitp.kiev.ua/event/18/contributions/549/
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