Stokes Phenomena and Non-perturbative Completion in the Multi-cut Two-matrix Models

The Stokes multipliers in the matrix models are invariants in the string-theory moduli space and related to the D-instanton chemical potentials. They not only represent non-perturbative information but also play an important role in connecting various perturbative string theories in the moduli space. They are a key concept to the non-perturbative completion of string theory and also expected to imply some remnant of strong coupling dynamics in M theory. In this paper, we investigate the non-perturbative completion problem consisting of two constraints on the Stokes multipliers. As the first constraint, Stokes phenomena which realize the multi-cut geometry are studied in the Z_k symmetric critical points of the multi-cut two-matrix models. Sequence of solutions to the constraints are obtained in general k-cut critical points. A discrete set of solutions and a continuum set of solutions are explicitly shown, and they can be classified by several constrained configurations of the Young diagram. As the second constraint, we discuss non-perturbative stability of backgrounds in terms of the Riemann-Hilbert problem. In particular, our procedure in the 2-cut (1,2) case (pure-supergravity case) completely fixes the D-instanton chemical potentials and results in the Hastings-McLeod solution to the Painlev\'e II equation. It is also stressed that the Riemann-Hilbert approach realizes an off-shell background independent formulation of non-critical string theory.Comment: 71 pages, v3: organization of Sec. 3, Sec. 4, App. C and App. D improved, final version to be published in Nucl. Phys.

Duality Constraints on String Theory: Instantons and spectral networks

We study an implication of $p-q$ duality (spectral duality or T-duality) on non-perturbative completion of $(p,q)$ minimal string theory. According to the Eynard-Orantin topological recursion, spectral $p-q$ duality was already checked for all-order perturbative analysis including instanton/soliton amplitudes. Non-perturbative realization of this duality, on the other hand, causes a new fundamental issue. In fact, we find that not all the non-perturbative completions are consistent with non-perturbative $p-q$ duality; Non-perturbative duality rather provides a constraint on non-perturbative contour ambiguity (equivalently, of D-instanton fugacity) in matrix models. In particular, it prohibits some of meta-stability caused by ghost D-instantons, since there is no non-perturbative realization on the dual side in the matrix-model description. Our result is the first quantitative observation that a missing piece of our understanding in non-perturbative string theory is provided by the principle of non-perturbative string duality. To this end, we study Stokes phenomena of $(p,q)$ minimal strings with spectral networks and improve the Deift-Zhou's method to describe meta-stable vacua. By analyzing the instanton profile on spectral networks, we argue the duality constraints on string theory.Comment: v1: 84 pages, 43 figures; v2: 86 pages, 43 figures, presentations are improved, references added; v3: 126 pages, 69 figures: a solution of local RHP, physics of resolvents, commutativity of integrals are newly added; organization is changed and explanations are expanded to improve representation with addition of review, proofs and calculations; some definitions are changed; references adde

Wronskians, dualities and FZZT-Cardy branes

The resolvent operator plays a central role in matrix models. For instance, with utilizing the loop equation, all of the perturbative amplitudes including correlators, the free-energy and those of instanton corrections can be obtained from the spectral curve of the resolvent operator. However, at the level of non-perturbative completion, the resolvent operator is generally not sufficient to recover all the information from the loop equations. Therefore it is necessary to find a sufficient set of operators which provide the missing non-perturbative information. In this paper, we study generalized Wronskians of the Baker-Akhiezer systems as a manifestation of these new degrees of freedom. In particular, we derive their isomonodromy systems and then extend several spectral dualities to these systems. In addition, we discuss how these Wronskian operators are naturally aligned on the Kac table. Since they are consistent with the Seiberg-Shih relation, we propose that these new degrees of freedom can be identified as FZZT-Cardy branes in Liouville theory. This means that FZZT-Cardy branes are the bound states of elemental FZZT branes (i.e. the twisted fermions) rather than the bound states of principal FZZT-brane (i.e. the resolvent operator).Comment: 131 pages, 4 figure

Analytic Study for the String Theory Landscapes via Matrix Models

We demonstrate a first-principle analysis of the string theory landscapes in the framework of non-critical string/matrix models. In particular, we discuss non-perturbative instability, decay rate and the true vacuum of perturbative string theories. As a simple example, we argue that the perturbative string vacuum of pure gravity is stable; but that of Yang-Lee edge singularity is inescapably a false vacuum. Surprisingly, most of perturbative minimal string vacua are unstable, and their true vacuum mostly does not suffer from non-perturbative ambiguity. Importantly, we observe that the instability of these tachyon-less closed string theories is caused by ghost D-instantons (or ghost ZZ-branes), the existence of which is determined only by non-perturbative completion of string theory.Comment: v1: 5 pages, 2 figures; v2: references and footnote added; v3: 7 pages, 4 figures, organization changed, explanations expanded, references added, reconstruction program from arbitrary spectral curves shown explicitl

Three-dimensional imaging of crack growth in L chondrites after high-velocity impact experiments

Small asteroids such as Itokawa are covered with an unconsolidated regolith layer of centimeter-sized or smaller particles. There are two plausible formation mechanisms for regolith layers on a sub-kilometer-sized asteroid: (i) fragments produced by thermal fatigue by day-night temperature cycles on the asteroid surface and (ii) impact fragment. Previous studies suggest that thermal fatigue induces crack growth along the boundary surface of the mineral grain while impact phenomena may induce crack growth regardless of the boundary surface of the mineral grain. Therefore, it is possible that the crack growth within a mineral grain (and/or a chondrule) differs depending on the crack formation mechanism, be it thermal fatigue or an impact. In order to investigate how mineral grains and chondrules are affected by impact-induced crack growth, we fired spherical alumina projectiles (diameter ~1 mm) into 9 mm side length cubic targets of L chondrites at a nominal impact velocity of 2.0 km/s. Before and after the six successful impact experiments, the cracks within mineral grains and chondrules in the respective targets are examined using X-ray microtomography at a resolution with the voxel size of 9.0 μm. The results show that most cracks within chondrules and troilite (FeS) grow regardless of the boundary surfaces of the grains while most cracks within ductile Fe-Ni metal grow along the boundary surfaces of the grains. This may indicate that crack growth is largely affected by the strength of mineral grains (and/or chondrules). From the experimental results and the fact that the shapes of polymineralic and monomineralic particles from Itokawa are similar, we conclude that the Itokawa particles have not been produced by thermal fatigue but instead are likely to be impact fragments, as described in previous papers (Tsuchiyama et al., 2011, 2014; Michikami et al., 2018)

Macroscopic loop amplitudes in the multi-cut two-matrix models

Multi-cut critical points and their macroscopic loop amplitudes are studied in the multi-cut two-matrix models, based on an extension of the prescription developed by Daul, Kazakov and Kostov. After identifying possible critical points and potentials in the multi-cut matrix models, we calculate the macroscopic loop amplitudes in the Z_k symmetric background. With a natural large N ansatz for the matrix Lax operators, a sequence of new solutions for the amplitudes in the Z_k symmetric k-cut two-matrix models are obtained, which are realized by the Jacobi polynomials.Comment: 46 pages, 3 figures; v2: 51 pages, 7 figures, notations changed, explanations in Section 2.4 extended, figures for topology of the curves added, Appendix E added, final version to appear in Nucl. Phys.

Fractional-Superstring Amplitudes, Multi-Cut Matrix Models and Non-Critical M Theory

Multi-cut two-matrix models are studied in the Z_k symmetry breaking k-cut (\hat p,\hat q) critical points which should correspond to (\hat p,\hat q) minimal k-fractional superstring theory. FZZT-brane or macroscopic loop amplitudes are obtained in all of these critical points and found to have two kinds of solutions in general. Each of these solutions is expressed by hyperbolic cosine or sine functions with proper phase shifts. The algebraic geometries and ZZ-brane disk amplitudes (instanton actions) of these solutions are also studied. In particular, our results suggest that minimal \infty-fractional superstring theory can be viewed as a mother theory which includes all the minimal k-fractional superstring theories (k=1,2,...) as its perturbative vacua in the weak-coupling string landscape. Our results also indicate that, in the strong coupling regime of this fractional superstring theory, there is a three-dimensional theory which would be understood as the non-critical version of M theory in the sense proposed by P. Horava and C. A. Keeler.Comment: 47 pages, 6 figures; references added v