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(abridged) Both fundamental constants that describe the laws of physics and cosmological parameters that determine the cosmic properties must fall within a range of values in order for the universe to develop astrophysical structures and…

Cosmology and Nongalactic Astrophysics · Physics 2019-09-25 Fred C. Adams

We propose that the existence of the string landscape suggests the universe can be in a quantum glass state, where an extremely large viscosity is generated, and long distance dynamics slows down. At the same time, the short distance…

High Energy Physics - Theory · Physics 2010-10-27 Jian-Huang She

Motivated by some recent speculative attempts to model the dark energy, scalar fields with negative kinetic energy coupled to gravity without a cosmological constant are considered. It is shown that in the presence of an ordinary fluid, any…

High Energy Physics - Theory · Physics 2007-05-23 G. W. Gibbons

We consider the ability of local quantum dynamics to solve the energy matching problem: given an instance of a classical optimization problem and a low energy state, find another macroscopically distinct low energy state. Energy matching is…

Disordered Systems and Neural Networks · Physics 2018-06-20 C. L. Baldwin , C. R. Laumann

The concordance model of cosmology suffers from the major theoretical problems surrounding the observed value and recent emergence of a cosmological constant. In this paper we present a novel approach, which explains more naturally its…

General Relativity and Quantum Cosmology · Physics 2020-03-18 J. Lorca Espiro , M. Le Delliou

A mechanism is introduced to reduce a large cosmological constant to a sufficiently small value consistent with observational upper limit. The basic ingradient in this mechanism is a distinction which has been made between the two unit…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Y. Bisabr , H. Salehi

The typical scalar field theory has a cosmological constant problem. We propose a generic mechanism by which this problem is avoided at tree level by embedding the theory into a larger theory. The metric and the scalar field coupling…

High Energy Physics - Phenomenology · Physics 2012-07-11 Roman V. Buniy , Thomas W. Kephart

In quantum cosmology the closed universe can spontaneously nucleate out of the state with no classical space and time. For the universe filled with a vacuum of constant energy density the semiclassical tunneling nucleation probability can…

High Energy Physics - Theory · Physics 2016-09-06 A. V. Yurov , V. A. Yurov

We discuss a possible mechanism to screen a cosmological constant in non-local gravity. We find that in a simple model of of non-local gravity with the Lagrangian of the form, $R+f(\Box^{-1}R)-2\Lambda$ where $f(X)$ is a quadratic function…

General Relativity and Quantum Cosmology · Physics 2011-01-27 Shin'ichi Nojiri , Sergei D. Odintsov , Misao Sasaki , Ying-li Zhang

In many practical applications, heuristic or approximation algorithms are used to efficiently solve the task at hand. However their solutions frequently do not satisfy natural monotonicity properties of optimal solutions. In this work we…

Machine Learning · Computer Science 2020-03-24 Evangelia Gergatsouli , Brendan Lucier , Christos Tzamos

A quantum algorithm for general combinatorial search that uses the underlying structure of the search space to increase the probability of finding a solution is presented. This algorithm shows how coherent quantum systems can be matched to…

Quantum Physics · Physics 2009-10-30 Tad Hogg

Parameterized complexity enables the practical solution of generally intractable NP-hard problems when certain parameters are small, making it particularly useful in real-world applications. The study of string problems in this framework…

Quantum Physics · Physics 2025-10-20 Josh Cudby , Sergii Strelchuk

The minimum distance is one of the most important combinatorial characterizations of a code. The maximum likelihood decoding problem is one of the most important algorithmic problems of a code. While these problems are known to be hard for…

Information Theory · Computer Science 2016-08-31 Qi Cheng

We exhibit a probabilistic algorithm which computes a rational point of an absolutely irreducible variety over a finite field defined by a reduced regular sequence. Its time--space complexity is roughly quadratic in the logarithm of the…

Number Theory · Mathematics 2007-05-23 Antonio Cafure , Guillermo Matera

It is suggested that the exact value of the cosmological constant could be derived from first principles, based on entanglement of the Standard Model field vacuum with emergent holographic quantum geometry. For the observed value of the…

General Relativity and Quantum Cosmology · Physics 2018-04-03 Craig Hogan

Max-cut, clustering, and many other partitioning problems that are of significant importance to machine learning and other scientific fields are NP-hard, a reality that has motivated researchers to develop a wealth of approximation…

Data Structures and Algorithms · Computer Science 2018-10-17 Maria-Florina Balcan , Vaishnavh Nagarajan , Ellen Vitercik , Colin White

Recent cosmological observations suggest the existence of a positive cosmological constant $\Lambda$ with the magnitude $\Lambda(G\hbar/c^3) \approx 10^{-123}$. This review discusses several aspects of the cosmological constant both from…

High Energy Physics - Theory · Physics 2008-11-26 T. Padmanabhan

The paper deals with the scale discrepancy between the observed vacuum energy in cosmology and the theoretical quantum vacuum energy (cosmological constant problem). Here, we demonstrate that Einstein's equation and an analogy to particle…

General Physics · Physics 2019-02-08 Christian Henke

The presence of a cosmological constant, Lambda, in an action with higher powers of the curvature can produce rapidly oscillating metrics. We develop a perturbative approach for generating periodic solutions to the non-linear field…

High Energy Physics - Theory · Physics 2009-11-07 Hael Collins , Bob Holdom

An alternative to dark energy as an explanation for the present phase of accelerated expansion of the Universe is that the Friedmann equation is modified, e.g. by extra dimensional gravity, on large scales. We explore a natural…

Astrophysics · Physics 2009-11-10 Oystein Elgaroy , Tuomas Multamaki