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T. Banks

Publications and source records attributed to T. Banks.

At least 91 records · Page 5Linked to original sources
arXiv2005

Infrared Divergences in dS/CFT

dS/CFT gives a perturbatively gauge invariant definition of particle masses in de Sitter (dS) space. We show, in a toy model in which the graviton is replaced with a minimally coupled massless scalar field, that loop corrections to these masses are infrared (IR) divergent. We argue that this implies anomalous dependence of masses on the cosmological constant, in a true theory of quantum gravity. This is in accord with the hypothesis of Cosmological SUSY Breaking (CSB).

hep-th↗
arXiv2005

A Dark Matter Candidate with New Strong Interactions

We study the possibility that dark matter is a baryon of a new strongly interacting gauge theory, which was introduced in the low energy theory of Cosmological SUSY Breaking (CSB). This particle can fit the observed dark matter density if an appropriate cosmological asymmetry is generated. The same mechanism can also explain the dark/baryonic matter ratio in the universe. The mass of the dark matter particle is in the multiple TeV range, and could be as high as 20 TeV.

hep-ph↗
arXiv2005

Some Thoughts on the Quantum Theory of Stable de Sitter Space

I review and update ideas about the quantum theory of de Sitter space. New results include a quantum relation between energy and entropy of states in the causal patch, which is satisfied by small dS black holes. I also discuss the preliminaries of a quantum theory in global coordinates, which is invariant under a q-deformed version of the de Sitter supergroup. In this context I outline an algebraic derivation of the CSB scaling relation between Poincare SUSY breaking and the dS radius. I also review recent work on infra-red divergences in dS/CFT, as well as the phenomenology of CSB. I show that a coincidence been two scales in the phenomenological model is explained by insisting on the existence of galaxies.

hep-th↗
arXiv2004

Landskepticism: or Why Effective Potentials Don't Count String Models

This paper is a synthesis of talks I gave at the Cargese Workshop in June 2004 and the Munich Conference on Superstring Vacua in November 2004. I present arguments which show that the landscape of string theory is not a well established feature of the theory, as well as a brief discussion of the phenomenological prospects of the landscape and the use of the anthropic principle.

hep-th↗
arXiv2004

The Holographic Approach to Cosmology

We review the successes and challenges of the holographic approach to cosmology. The model predicts an exactly scale invariant fluctuation spectrum with long and short distance cut-offs. It can account for the observed fluctuations in the CMB and might explain the low power at large scales. We outline various cosmological histories compatible with holographic initial conditions. This paper is based on talks given by the authors at Cosmo 04 in Toronto, and the 2004 Tamura Symposium in Austin

hep-th↗
arXiv2004

Tensor algebras and displacement structure. IV. Invariant kernels

In this paper we investigate the class of invariant positive definite kernels on the free semigroup on N generators. We provide a combinatorial description of the positivity of the kernel in terms of Dyck paths and then we find a displacement equation that encodes the invariance property of the kernel.

math.FA↗
arXiv2004

A New Approach to the Phenomenology of Cosmological Supersymmetry Breaking

I introduce a new low energy effective description of Cosmological SUSY breaking. It requires the existence of a strongly interacting gauge theory at a scale of order $10^3$ GeV, some of whose fields carry standard model quantum numbers. SUSY breaking is communicated to the standard model through gaugino masses and the Higgs multiplets. The model also provides a possible new solution of the strong CP problem

hep-ph↗
arXiv2004

Microscopic Quantum Mechanics of the p=ρUniverse

We present a complete quantum mechanical description of a flat FRW universe with equation of state p=ρ. We find a detailed correspondence with our heuristic picture of such a universe as a dense black hole fluid. Features of the geometry are derived from purely quantum input.

hep-th↗
arXiv2004

Holographic Cosmology

We describe a cosmology of the very early universe, based on the holographic principle of 't Hooft and Susskind. We have described the initial state as a dense black hole fluid. Here we present a mathematical model of this heuristic picture, as well as a non-rigorous discussion of how a more normal universe could evolve out of such a state. The gross features of the cosmology depend on a few parameters, which cannot yet be calculated from first principles. For some range of these parameters, microwave background fluctuations originate from fluctuations in the black hole fluid, and have characteristics different from those of most inflationary models.

hep-th↗
arXiv2004

An upper bound on the number of e-foldings

If the present acceleration of the universe is due to an asymptotically de Sitter universe with small cosmological constant, and the principle of Cosmological Complementarity is valid, then the number of e-foldings during inflation is bounded.

astro-ph↗
arXiv2003

Relations on noncommutative variables and associated orthogonal polynomials

This semi-expository paper surveys results concerning three classes of orthogonal polynomials: in one non-hermitian variable, in several isometric non-commuting variables, and in several hermitian non-commuting variables. The emphasis is on some dilation theoretic techniques that are also described in some details.

math.FA↗
arXiv2003

Supersymmetry, Axions and Cosmology

Various authors have noted that in particular models, the upper bound on the axion decay constant may not hold. We point out that within supersymmetry, this is a generic issue. For large decay constants, the cosmological problems associated with the axion's scalar partner are far more severe than those of the axion. We survey a variety of models, both for the axion multiplet and for cosmology, and find that in many cases where the cosmological problems of the saxion are solved, the usual upper bound on the axion is significantly relaxed. We discuss, more generally, the cosmological issues raised by the pseudoscalar members of moduli multiplets, and find that they are potentially quite severe.

hep-ph↗
arXiv2003

Holographic Cosmology 3.0

We present a new version of holographic cosmology, which is compatible with present observations. A primordial $p=ρ$ phase of the universe is followed by a brief matter dominated era and a brief period of inflation, whose termination heats the universe. The flatness and horizon problems are solved by the $p=ρ$ dynamics. The model is characterized by two parameters, which should be calculable in a more fundamental approach to the theory. For a large range in the phenomenologically allowed parameter space, the observed fluctuations in the cosmic microwave background were generated during the $p=ρ$ era, and are exactly scale invariant. The scale invariant spectrum cuts off sharply at both upper and lower ends, and this may have observational consequences. We argue that the amplitude of fluctuations is small but cannot yet calculate it precisely.

hep-th↗
arXiv2003

A Critique of Pure String Theory: Heterodox Opinions of Diverse Dimensions

I present a point of view about what M Theory is and how it is related to the real world, which departs in certain crucial respects from conventional wisdom. I argue against the possibility of a background independent formulation of the theory, or of a Poincare invariant, Supersymmetry violating vacuum state. A fundamental assumption is black hole dominance of high energy physics. Much of this paper is a compilation of things I have said elsewhere. I review a crude argument for the critical exponent connecting the gravitino mass and the cosmological constant, and propose a framework for finding a quantum theory of de Sitter space.

hep-th↗
arXiv2003

Supersymmetry, the Cosmological Constant and a Theory of Quantum Gravity in Our Universe

There are many theories of quantum gravity, depending on asymptotic boundary conditions, and the amount of supersymmetry. The cosmological constant is one of the fundamental parameters that characterize different theories. If it is positive, supersymmetry must be broken. A heuristic calculation shows that a cosmological constant of the observed size predicts superpartners in the TeV range. This mechanism for SUSY breaking also puts important constraints on low energy particle physics models. This essay was submitted to the Gravity Research Foundation Competition and is based on a longer article, which will be submitted in the near future.

hep-th↗
arXiv2003

SUSY and the Holographic Screens

The Cartan-Penrose (CP) equation is interpreted as a connection between a spinor at a point in spacetime, and a pair of holographic screens on which the information at that point may be projected. Local SUSY is thus given a physical interpretation in terms of the ambiguity of the choice of holographic screen implicit in the work of Bousso. The classical CP equation is conformally invariant, but quantization introduces metrical information via the B(ekenstein)-H(awking)-F(ischler)-S(usskind)-B(ousso) connection between area and entropy. A piece of the classical projective invariance survives as the $(-1)^F$ operation of Fermi statistics. I expand on a previously discussed formulation of quantum cosmology, using the connection between SUSY and screens.

hep-th↗
arXiv2003

Some Thoughts on the Quantum Theory of de Sitter Space

This is a summary of two lectures I gave at the Davis Conference on Cosmic Inflation. I explain why the quantum theory of de Sitter (dS) space should have a finite number of states and explore gross aspects of the hypothetical quantum theory, which can be gleaned from semiclassical considerations. The constraints of a self-consistent measurement theory in such a finite system imply that certain mathematical features of the theory are unmeasurable, and that the theory is consequently mathematically ambiguous. There will be a universality class of mathematical theories all of whose members give the same results for local measurements, within the {\it a priori} constraints on the precision of those measurements, but make different predictions for unmeasurable quantities, such as the behavior of the system on its Poincare recurrence time scale. A toy model of dS quantum mechanics is presented.

astro-ph↗