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| Format: | Preprint |
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2025
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| Online Access: | https://arxiv.org/abs/2508.01497 |
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| _version_ | 1866909719126343680 |
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| author | Bahamondes, Sebastián |
| author_facet | Bahamondes, Sebastián |
| contents | In this thesis we build a phenomenological, strongly
coupled quantum field theory in $2+1$-dimensions through AdS/CFT holography,
by building a $3+1$-dimensional, negatively curved gravity theory with a $SU(2)$ gauge field,
and a scalar field in the adjoint of $SU(2)$. We locate a phase transition between two distinct phases at zero and finite temperature, which
are characterized through the dispersion relation of quasi-normal modes of probe fermions in the bulk,
and correspond either to a Dirac semimetal or a band insulator. These phases are separated by a
critical phase/critical point (depending if $T>0$ or $T=0$, respectively) where the band structure
of boundary fermions exhibits semi-Dirac anisotropy. We
characterize each phase at $T=0$ by explicit solutions to the bulk equations of motion in the infra-red,
and determine that the critical point's spacetime is a Lifshitz geometry, whose dynamical critical exponent is
approximately equal to $2$. We also find that this anisotropy induces a non-trivial
scaling of the shear viscosity-entropy density ratio with respect to temperature in the $T\to 0$ limit, and find evidence
that the anisotropic phase of the system corresponds to a finite-temperature quantum critical phase. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2508_01497 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Thermal and quantum phase transitions in a holographic anisotropic Dirac semimetal Bahamondes, Sebastián High Energy Physics - Theory Other Condensed Matter In this thesis we build a phenomenological, strongly coupled quantum field theory in $2+1$-dimensions through AdS/CFT holography, by building a $3+1$-dimensional, negatively curved gravity theory with a $SU(2)$ gauge field, and a scalar field in the adjoint of $SU(2)$. We locate a phase transition between two distinct phases at zero and finite temperature, which are characterized through the dispersion relation of quasi-normal modes of probe fermions in the bulk, and correspond either to a Dirac semimetal or a band insulator. These phases are separated by a critical phase/critical point (depending if $T>0$ or $T=0$, respectively) where the band structure of boundary fermions exhibits semi-Dirac anisotropy. We characterize each phase at $T=0$ by explicit solutions to the bulk equations of motion in the infra-red, and determine that the critical point's spacetime is a Lifshitz geometry, whose dynamical critical exponent is approximately equal to $2$. We also find that this anisotropy induces a non-trivial scaling of the shear viscosity-entropy density ratio with respect to temperature in the $T\to 0$ limit, and find evidence that the anisotropic phase of the system corresponds to a finite-temperature quantum critical phase. |
| title | Thermal and quantum phase transitions in a holographic anisotropic Dirac semimetal |
| topic | High Energy Physics - Theory Other Condensed Matter |
| url | https://arxiv.org/abs/2508.01497 |