arXiv subjects

Djordje Minic

Publications and source records attributed to Djordje Minic.

At least 109 records · Page 6Linked to original sources

arXiv2010

Cold Dark Matter with MOND Scaling

We provide a holographic dual description of Milgrom's scaling associated with galactic rotation curves. Our argument is based on the recent entropic reinterpretation of Newton's laws of motion. We propose a duality between cold dark matter and modified Newtonian dynamics (MOND). We introduce the concept of MONDian dark matter, and discuss some of its phenomenological implications. At cluster as well as cosmological scales, the MONDian dark matter would behave as cold dark matter, but at the galactic scale, the MONDian dark matter would act as MOND.

hep-th↗

arXiv2010

Aging and Holography

Aging phenomena are examples of `non-equilibrium criticality' and can be exemplified by systems with Galilean and scaling symmetries but no time translation invariance. We realize aging holographically using a deformation of a non-relativistic version of gauge/gravity duality. Correlation functions of scalar operators are computed using holographic real-time techniques, and agree with field theory expectations. At least in this setup, general aging phenomena are reproduced holographically by complexifying the bulk space-time geometry, even in Lorentzian signature.

hep-th↗

arXiv2010

Robustness of topologically protected surface states in layering of Bi2Te3 thin films

Bulk Bi2Te3 is known to be a topological insulator. We investigate surface states of Bi2Te3(111) thin films using density-functional theory including spin-orbit coupling. We construct a method to unambiguously identify surface states of thin film topological insulators. Applying this method for one to six quintuple layers of Bi2Te3, we find that the topological nature of the surface states remains robust with the film thickness and that the films of three or more quintuple layers have topologically non-trivial or protected surface states, in agreement with recent experiments.

cond-mat.mes-hall↗

arXiv2010

Quantum Gravity and Turbulence

We apply recent advances in quantum gravity to the problem of turbulence. Adopting the AdS/CFT approach we propose a string theory of turbulence that explains the Kolmogorov scaling in 3+1 dimensions and the Kraichnan and Kolmogorov scalings in 2+1 dimensions. In the gravitational context, turbulence is intimately related to the properties of spacetime, or quantum, foam.

gr-qc↗

arXiv2010

String Theory and Turbulence

We propose a string theory of turbulence that explains the Kolmogorov scaling in 3+1 dimensions and the Kraichnan and Kolmogorov scalings in 2+1 dimensions. This string theory of turbulence should be understood in light of the AdS/CFT dictionary. Our argument is crucially based on the use of Migdal's loop variables and the self-consistent solutions of Migdal's loop equations for turbulence. In particular, there is an area law for turbulence in 2+1 dimensions related to the Kraichnan scaling.

hep-th↗

arXiv2010

Quantum Gravity, Dynamical Energy-Momentum Space and Vacuum Energy

We argue that the combination of the principles of quantum theory and general relativity allow for a dynamical energy-momentum space. We discuss the freezing of vacuum energy in such a dynamical energy-momentum space and present a phenomenologically viable seesaw formula for the cosmological constant in this context.

hep-th↗

arXiv2010

On the Physics of the Riemann Zeros

We discuss a formal derivation of an integral expression for the Li coefficients associated with the Riemann xi-function which, in particular, indicates that their positivity criterion is obeyed, whereby entailing the criticality of the non-trivial zeros. We conjecture the validity of this and related expressions without the need for the Riemann Hypothesis and discuss a physical interpretation of this result within the Hilbert-Polya approach. In this context we also outline a relation between string theory and the Riemann Hypothesis.

hep-th↗

arXiv2010

Gauge Fields, Membranes and Subdeterminant Vector Models

We present a class of classically marginal N-vector models in d=4 and d=3, whose scalar potentials can be written as subdeterminants of symmetric matrices. The d=3 case is a generalization of the scalar Bagger-Lambert-Gustavsson (BLG) model. Using the Hubbard-Stratonovich transformation we calculate their effective potentials which exhibit intriguing large-N scaling behaviors. We comment on the relevance of our models to strings, membranes and also to a class of novel spin systems that are based on ternary commutation relations.

hep-th↗

arXiv2009

The Effect of the Minimal Length Uncertainty Relation on the Density of States and the Cosmological Constant Problem

We investigate the effect of the minimal length uncertainty relation, motivated by perturbative string theory, on the density of states in momentum space. The relation is implemented through the modified commutation relation [x_i,p_j]=i hbar[(1 + beta p^2) delta_{ij} + beta' p_i p_j]. We point out that this relation, which is an example of an UV/IR relation, implies the finiteness of the cosmological constant. While our result does not solve the cosmological constant problem, it does shed new light on the relation between this outstanding problem and UV/IR correspondence. We also point out that the blackbody radiation spectrum will be modified at higher frequencies, but the effect is too small to be observed in the cosmic microwave background spectrum.

hep-th↗

arXiv2009

The Big Bang as the Ultimate Traffic Jam

We present a novel solution to the nature and formation of the initial state of the Universe. It derives from the physics of a generally covariant extension of Matrix theory. We focus on the dynamical state space of this background independent quantum theory of gravity and matter, an infinite dimensional, complex non-linear Grassmannian. When this space is endowed with a Fubini--Study-like metric, the associated geodesic distance between any two of its points is zero. This striking mathematical result translates into a physical description of a hot, zero entropy Big Bang. The latter is then seen as a far from equilibrium, large fluctuation driven, metastable ordered transition, a ``freezing by heating'' jamming transition. Moreover, the subsequent unjamming transition could provide a mechanism for inflation while rejamming may model a Big Crunch, the final state of gravitational collapse.

gr-qc↗

arXiv2009

Eigenvalue Density, Li's Positivity, and the Critical Strip

We rewrite the zero-counting formula within the critical strip of the Riemann zeta function as a cumulative density distribution; this subsequently allows us to formally derive an integral expression for the Li coefficients associated with the Riemann xi-function which, in particular, indicate that their positivity criterion is obeyed, whereby entailing the criticality of the non-trivial zeros. We conjecture the validity of this and related expressions without the need for the Riemann Hypothesis and also offer a physical interpretation of the result and discuss the Hilbert-Polya approach.

math-ph↗

arXiv2008

High Temperature Superconductivity and Effective Gravity

We argue that an approach involving effective gravity could play a crucial role in elucidating the properties of the high temperature superconducting materials. In particular we propose that the high critical temperature might be naturally explained in a framework constructed as a direct condensed matter analog of the Randall-Sundrum approach to a geometrization of the hierarchy problem in high-energy physics.

hep-th↗

arXiv2008

Non-relativistic AdS/CFT and Aging/Gravity Duality

We point out that the recent discussion of non-relativistic AdS/CFT correspondence has a direct application in non-equilibrium statistical physics, the fact which has not been emphasized in the recent literature on the subject. In particular, we propose a duality between aging in systems far from equilibrium characterized by the dynamical exponent $z=2$ and gravity in a specific background. The key ingredient in our proposal is the recent geometric realization of the Schrödinger group. We also discuss the relevance of the proposed correspondence for the more general aging phenomena in systems where the value of the dynamical exponent is different from 2.

cond-mat.stat-mech↗

arXiv2008

Turbulence and Holography

We examine the interplay between recent advances in quantum gravity and the problem of turbulence. In particular, we argue that in the gravitational context the phenomenon of turbulence is intimately related to the properties of spacetime foam. In this framework we discuss the relation of turbulence and holography and the interpretation of the Kolmogorov scaling in the quantum gravitational setting.

hep-th↗

arXiv2008

Transient Astrophysical Pulses and Quantum Gravity

Searches for transient astrophysical pulses could open an exciting new window into the fundamental physics of quantum gravity. In particular, an evaporating primordial black hole in the presence of an extra dimension can produce a detectable transient pulse. Observations of such a phenomenon can in principle explore the electroweak energy scale, indicating that astrophysical probes of quantum gravity can successfully complement the exciting new physics expected to be discovered in the near future at the Large Hadron Collider.

gr-qc↗

arXiv2008

On the Origin of Time and the Universe

We present a novel solution to the low entropy and arrow of time puzzles of the initial state of the Universe. Our approach derives from the physics of a specific generalization of Matrix theory put forth in earlier work as the basis for a quantum theory of gravity. The particular dynamical state space of this theory, the infinite dimensional analogue of the Fubini-Study metric over a complex non-linear Grassmannian, has recently been studied by Michor and Mumford. The geodesic distance between any two points on this space is zero. Here we show that this mathematical result translates to a description of a hot, zero entropy state and an arrow of time after the Big Bang. This is modeled as a far from equilibrium, large fluctuation driven, "freezing by heating" metastable ordered phase transition of a non-linear dissipative dynamical system.

hep-th↗

arXiv2008

On the spectrum of pure Yang-Mills theory

In this note we discuss the wave functional approach to the spectrum of pure Yang-Mills theory in 2+1 and 3+1 dimensions by highlighting the issues of dynamical mass generation and the role played by the kinetic term. We extrapolate our recent analysis of 2+1 Yang-Mills theory to 3+1 dimensions, and under certain heuristic assumptions use a simple quasi-Gaussian vacuum wavefunctional for 3+1 Yang-Mills theory for a preliminary study of the spectrum of glueballs which nicely fits the available lattice simulations.

hep-th↗

arXiv2007

Time and M-theory

We review our recent proposal for a background independent formulation of a holographic theory of quantum gravity. The present review incorporates the necessary background material on geometry of canonical quantum theory, holography and spacetime thermodynamics, Matrix theory, as well as our specific proposal for a dynamical theory of geometric quantum mechanics, as applied to Matrix theory. At the heart of this review is a new analysis of the conceptual problem of time and the closely related and phenomenologically relevant problem of vacuum energy in quantum gravity. We also present a discussion of some observational implications of this new viewpoint on the problem of vacuum energy.

hep-th↗