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- Chen-Lin, Xinyi
(författare)
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Non-conformal gauge/string duality : A rigorous case study
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The gauge/string duality, a.k.a. the holographic principle is a profound assertion that emerged from string theory. It relates strongly-coupled gauge theories to weakly coupled string theories living in a higher-dimensional curved geometry. Nevertheless, it is a conjecture, and only a few instances of its more concrete form, the AdS/CFT correspondence, are well-understood. The most well-studied example is the duality between N=4 SYM, which is a CFT, and type IIB string theory in AdS5xS5 background. Generalization to less symmetric cases is a must, and the next logical step is to add a mass scale to N=4 SYM, therefore breaking its conformal symmetry and leading to N=2* SYM, the theory we study in this thesis. It is supersymmetric enough to employ the powerful localization method that reduces its partition function to a matrix model. We will see that the mass scale causes non-trivial phase structures in its vacuum configuration, visible in the holographic regime. We will probe them using Wilson loops in different representations of the gauge group. On the other hand, the dual supergravity background was derived by Pilch-Warner, making N=2* theory an explicitly testable non-conformal holographic case, which is a rare example. We will prove that the duality works for the dual observables (string action, D-branes) we managed to compute, even at a quantum-level.
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| 2. |
- Widen, Erik, 1986-
(författare)
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Exact Results in Supersymmetric Field Theories : A dissertation on the defect and deformed
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Quantum field theories (QFTs) are the most precise descriptions of the physical reality that humanity has found. Yet exact predictions are often missing as most computations are notoriously difficult to carry out. One generally resorts to perturbation theory which immediately limits the regime of validity. The need of better computational techniques and a deeper understanding of quantum field theory is evident.The highly symmetric N=4 SYM theory offers guidance in this quest. The theory's maximal supersymmetry and conformal invariance have allowed for the development of several computational techniques, most notably the AdS/CFT correspondence, supersymmetric localization and applications of integrability. These methods provide the rarity of exact results in a fully interacting QFT and shine light on regimes inaccessible by traditional computations.The insights drawn from N=4 SYM can be extended into more general settings through deformations and modifications. Three such modifications are the β-deformation, the massive deformation N=2* and N=4 SYM with a defect. This thesis summarizes a number of exact results for these three settings through: i) a spin-chain analogy for two-point functions in the defect N=4 SYM, ii) a vacuum solution for the β-deformed defect N=4 SYM and its spin-chain interpretation of one-point functions, iii) a detailed study of the phase transitions in N=2* applying localization and iv) an adaptation of the Quantum Spectral Curve to explicit calculations of anomalous dimensions in β-deformed N=4 SYM.
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| 3. |
- Medina Rincon, Daniel Ricardo, 1989-
(författare)
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Holographic Wilson Loops : Quantum String Corrections
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The gauge-string duality has been one of the most exciting areas in theoretical physics as it connects strongly coupled field theories with weakly interacting strings. The present thesis concerns the study of Wilson loops in this correspondence. Wilson loops are observables arising in many physical situations like the propagation of particles in gauge fields, the problem of confinement, etc. In the gauge-string correspondence these observables have a known physical description at both sides, making them ideal probes for the duality. Remarkable progress from localization has lead to predictions at all orders in the coupling for certain Wilson loop configurations in supersymmetric field theories. Being the string theory weakly interacting, in principle we can use perturbation theory to calculate the corresponding quantities. However, current string calculations have only been successful at leading order and in rare cases, next to leading order. At next to leading order the difficulties encountered include divergences, ambiguous boundary conditions, mismatch with field theory results, etc. The research presented in this thesis aims at a better understanding of these issues. The first calculation presented here concerns the Wilson line in N=2*, a massive deformation of N=4 SYM. The string theory dual to this configuration is a straight line in the type IIB Pilch-Warner background. Using techniques for functional determinants, we computed the 1-loop string partition function obtaining perfect matching with localization. This constitutes a first test of the correspondence at the quantum level for nonconformal theories. The second calculation in this thesis corresponds to the ratio of the latitude and circular Wilson loops in AdS5xS5. An IR anomaly related to the singular nature of the conformal gauge is shown to solve previously found discrepancies with field theory results.
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