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Some remarks on anthropic approaches to the strong CP problem

Abstract The peculiar value of θ is a challenge to the notion of an anthropic landscape. We briefly review the possibility that a suitable axion might arise from an anthropic requirement of dark matter. We then consider an alternative suggestion of Kaloper and Terning that θ might be correlated with the cosmological constant. We note that in a landscape one expects that θ is...

Classical and quantum stability in putative landscapes

Landscape analyses often assume the existence of large numbers of fields, N , with all of the many couplings among these fields (subject to constraints such as local supersymmetry) selected independently and randomly from simple (say Gaussian) distributions. We point out that unitarity and perturbativity place significant constraints on behavior of couplings with N , eliminating...

Light scalars and the cosmos: Nambu–Goldstone and otherwise†

This talk focuses on the role of light scalars in cosmology, both Nambu–Goldstone bosons and pseudo moduli. The former include QCD axions, which might constitute the dark matter, and more general axions, which, under certain conditions, might play the role of inflatons, implementing natural inflation. The latter are the actors in (generalized) hybrid inflation. They rather...

θ and the η ′ in large N supersymmetric QCD

We study the large N θ dependence and the η ′ potential in supersymmetric QCD with small soft SUSY-breaking terms. Known exact results in SUSY QCD are found to reflect a variety of expectations from large N perturbation theory, including the presence of branches and the behavior of theories with matter (both with N f ≪ N and N f ∼ N ). However, there are also striking departures...

Tunneling in theories with many fields

The possibility of a landscape of metastable vacua raises the question of what fraction of vacua are truly long lived. Naively any would-be vacuum state has many nearby decay paths, and all possible decays must be suppressed. An interesting model of this phenomena consists of N scalars with a random potential of fourth order. Here we show that the scaling of the typical minimal...

Challenges for the Nelson-Barr mechanism

The axion and m u = 0 solutions to the strong CP problem have been subject to the most careful scrutiny and critique. Basic theoretical issues include hierarchy and fine-tuning problems, quality and genericity of symmetries, and compatibility with solutions to the electroweak hierarchy problem. We study the similar set of challenges for solutions to strong CP based on spontaneous...

Hybrid inflation with Planck scale fields

Observable B-mode polarization in the CMBR would point to a high scale of inflation and large field excursions during the inflationary era. Non-compact string moduli spaces are a suggestive setting for these phenomena. Although they are unlikely to be described by weak coupling models, effective field theories compatible with known features of cosmology do exist. These models can...

Strong CP and SUZ2

Solutions to the strong CP problem typically introduce new scales associated with the spontaneous breaking of symmetries. Absent any anthropic argument for small \( \overline{\theta} \), these scales require stabilization against ultraviolet corrections. Supersymmetry offers a tempting stabilization mechanism, since it can solve the “big” electroweak hierarchy problem at the same...

Anomaly mediation in local effective theories

Michael Dine 0 Patrick Draper 0 0 Santa Cruz Institute for Particle Physics and Department of Physics , Santa Cruz CA 95064, U.S.A The phenomenon known as anomaly mediation can be understood in a

Discrete R symmetries and anomalies

Michael Dine 0 Angelo Monteux 0 0 Santa Cruz Institute for Particle Physics and Department of Physics, University of California Santa Cruz , Santa Cruz, CA 95064, U.S.A We comment on aspects of

Monodromy inflation in SUSY QCD

Michael Dine 0 Patrick Draper 0 Angelo Monteux 0 0 Santa Cruz Institute for Particle Physics, University of California Santa Cruz , 1156 High Street, Santa Cruz, U.S.A The discovery of a large

(Non-)decoupled supersymmetric field theories

We study some consequences of coupling supersymmetric theories to (super)gravity. To linear order, the couplings are determined by the energy-momentum supermultiplet. At higher orders, the couplings are determined by contact terms in correlation functions of the energy-momentum supermultiplet. We focus on the couplings of one particular field in the supergravity multiplet, the...

Proton decay at M pl and the scale of SUSY-breaking

Michael Dine 0 Patrick Draper 0 William Shepherd 0 0 Santa Cruz Institute for Particle Physics and Department of Physics , Santa Cruz CA 95064, U.S.A It is sometimes argued that a virtue of

A bound on the superpotential

We prove a general bound on the superpotential in theories with broken supersymmetry and broken R-symmetry, |〈W〉| \( \frac{1}{2} \) f a F, where f a and F are the R-axion and Goldstino decay constants, respectively. The bound holds for weakly coupled as well as strongly coupled theories, thereby providing an exact result in theories with broken supersymmetry. We briefly discuss...

Axions in the landscape and string theory

While axions seem ubiquitous in critical string theories, whether they might survive in any string theoretic description of nature is a difficult question. With some mild assumptions, one can frame the issues in the case that there is an approximate supersymmetry below the underlying string scale. The problem of axions is then closely tied to the question of how moduli are fixed...