Quantum nucleation of topological solitons

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Based on the chiral perturbation theory at the leading order, we show a signal of the presence of a new phase in rapidly rotating QCD matter with two flavors, that is a domain-wall Skyrmion phase. Based on the chiral Lagrangian with a Wess-Zumino-Witten (WZW) term responsible for the chiral anomaly and chiral vortical effect, it was shown that the ground state is a chiral soliton lattice (CSL) consisting of a stack of η-solitons in a high density region under rapid rotation. In a large parameter region, a single η-soliton decays into a pair of non-Abelian solitons, each of which carries SU(2)V/U(1) ≃ ℂP1 ≃ S2 moduli as a consequence of the spontaneously broken vector symmetry SU(2)V. In such a non-Abelian CSL, we construct the effective world-volume theory of a single non-Abelian soliton to obtain a d = 2 + 1 dimensional ℂP1 model with a topological term originated from the WZW term. We show that when the chemical potential is larger than a critical value, a topological lump supported by the second homotopy group π2(S2) ≃ ℤ has negative energy and is spontaneously created, implying the domain-wall Skyrmion phase. This lump corresponds in the bulk to a Skyrmion supported by the third homotopy group π3[SU(2)] ≃ ℤ carrying a baryon number. This composite state is called a domain-wall Skyrmion, and is stable even in the absence of the Skyrme term. An analytic formula for the effective nucleon mass in this medium can be written only in terms of the meson’s constants as $$ 4\sqrt{2}\pi {f}_{\pi }{f}_{\eta }/{m}_{\pi}\sim 1.21 $$ 4 2 π f π f η / m π ~ 1.21 GeV with the decay constants fπ and fη of the pions and η meson, respectively, and the pion mass mπ. This is reasonably heavier than the nucleon mass in the QCD vacuum.

mentioning

confidence: 69%

Domain-wall Skyrmion phase in a rapidly rotating QCD matter

Eto,

Nishimura,

Nitta

2024

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“…See, e.g., ref. [76] for three-dimensional configurations of a domain-wall disk bounded by a circular vortex loop. We firstly show a dynamical evolution of a randomly chosen initial configuration (t = 0) in the model of N = 1 in figure 9.…”

Section: Dynamics Of Vortex-wall Compositesmentioning

confidence: 99%

Composite topological solitons consisting of domain walls, strings, and monopoles in O(N) models

Eto,

Hamada,

Nitta

2023

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We study various composites of global solitons consisting of domain walls, strings, and monopoles in linear O(N) models with N = 2 and 3. Spontaneous symmetry breaking (SSB) of the O(N) symmetry down to O(N – 1) results in the vacuum manifold SN−1, together with a perturbed scalar potential in the presence of a small explicit symmetry breaking (ESB) interaction. The O(2) model is equivalent to the axion model admitting topological global (axion) strings attached by NDW domain walls. We point out for the NDW = 2 case that the topological stability of the string with two domain walls is ensured by sequential SSBs (ℤ2)2 → ℤ2 → 1, where the first SSB occurs in the vacuum leading to the topological domain wall as a mother soliton, only inside which the second SSB occurs giving rise to a subsequent kink inside the mother wall. From the bulk viewpoint, this kink is identical to a global string as a daughter soliton. This observation can be naturally ex- tended to the O(3) model, where a global monopole as a daughter soliton appears as a kink in a mother string or as a vortex on a mother domain wall, depending on ESB interactions. In the most generic case, the stability of the composite system consisting of the monopole, string, and domain wall is understood by the SSB (ℤ2)3 → (ℤ2)2 → ℤ2 → 1, in which the first SSB at the vacuum gives rise to the domain wall triggering the second one, so that the daughter string appears as a domain wall inside the mother wall triggering the third SSB, which leads to a granddaughter monopole as a kink inside the daughter vortex. We demonstrate numerical simulations for the dynamical evolution of the composite solitons.

“…On a more conceptual side, one might also wonder how a solitonic pion state carrying anomaly-induced baryon number might be dynamically created. This is a difficult question, and first works in this direction only appeared recently [6,7], suggesting nucleation of domain walls from the QCD vacuum similar to bubble nucleation in first-order phase transitions. Another important conceptual question is related to the one-dimensional modulation of the CSL state.…”

Section: Introductionmentioning

confidence: 99%

Chiral soliton lattice at next-to-leading order

Brauner

Kolešová

2023

We compute the free energy of the chiral soliton lattice state in quantum chromodynamics (QCD) at nonzero baryon chemical potential, temperature and external magnetic field at the next-to-leading order of chiral perturbation theory. This extends previous work where only a special limit of the chiral soliton lattice, the domain wall, was considered. Our results therefore serve as a consistency check of the previously established phase diagram of QCD at moderate magnetic fields and temperature and sub-nuclear baryon chemical potentials. Moreover, we use the result for the free energy to determine the magnetization carried by the domain wall and the chiral soliton lattice, both at the next-to-leading order.