Unitary Evolution and Cosmological Fine-Tuning (2010)
Carroll, Sean M., Tam, Heywood
Inflationary cosmology attempts to provide a natural explanation for the flatness and homogeneity of the observable universe. In the context of reversible (unitary) evolution, this goal is difficult...
Translational invariance and the anisotropy of the cosmic microwave background (2010)
Carroll, Sean M., Tseng, Chien-Yao, Wise, Mark B.
Primordial quantum fluctuations produced by inflation are conventionally assumed to be statistically homogeneous, a consequence of translational invariance. In this paper we quantify the potentially...
In the Shadow of the Transiting Disk: Imaging epsilon Aurigae in Eclipse (2010)
Kloppenborg, Brian, Stencel, Robert, Monnier, John D., Schaefer, Gail, Zhao, Ming, Baron, Fabien, ...
Eclipses of the single-line spectroscopic binary star, epsilon Aurigae, provide an opportunity to study the poorly-defined companion. We used the MIRC beam combiner on the CHARA array to create...
Infrared images of the transiting disk in the ε Aurigae system (2010)
Brian Kloppenborg, Robert Stencel, John D. Monnier, Gail Schaefer, Ming Zhao, Fabien Baron, ...
Implications of a scalar dark force for terrestrial experiments (2010)
Carroll, Sean M., Mantry, Sonny, Ramsey-Musolf, Michael J.
A long-range intergalactic force between dark matter (DM) particles, mediated by an ultralight scalar, is tightly constrained by galactic dynamics and large scale structure formation. We examine the...
Dark matter and dark radiation (2010)
Ackerman, Lotty, Buckley, Matthew R., Carroll, Sean M., Kamionkowski, Marc
We explore the feasibility and astrophysical consequences of a new long-range U(1) gauge field ("dark electromagnetism") that couples only to dark matter, not to the Standard Model. The dark matter...
Dynamical compactification from de Sitter space (2009)
Carroll, Sean M., Johnson, Matthew C., Randall, Lisa
We show that D-dimensional de Sitter space is unstable to the nucleation of non-singular geometries containing spacetime regions with different numbers of macroscopic dimensions, leading to a...
Extremal limits and black hole entropy (2009)
Carroll, Sean M., Johnson, Matthew C., Randall, Lisa
Taking the extremal limit of a non-extremal Reissner-Nordström black hole (by externally varying the mass or charge), the region between the inner and outer event horizons experiences an interesting...
Lorentz violation in Goldstone gravity (2009)
Carroll, Sean M., Tam, Heywood, Wehus, Ingunn Kathrine
We consider a theory of gravity in which a symmetric two-index tensor in Minkowski spacetime acquires a vacuum expectation value (vev) via a potential, thereby breaking Lorentz invariance...
Dark-matter-induced violation of the weak equivalence principle (2009)
Carroll, Sean M., Mantry, Sonny, Ramsey-Musolf, Michael J., Stubbs, Christopher W.
A long-range fifth force coupled to dark matter can induce a coupling to ordinary matter if the dark matter interacts with standard model fields. We consider constraints on such a scenario from both...
Lorentz Violation in Goldstone Gravity (2009)
Carroll, Sean M., Tam, Heywood, Wehus, Ingunn Kathrine
We consider a theory of gravity in which a symmetric two-index tensor in Minkowski spacetime acquires a vacuum expectation value (vev) via a potential, thereby breaking Lorentz invariance...
Dynamical compactification from de Sitter space (2009)
Carroll, Sean M., Johnson, Matthew C., Randall, Lisa
We show that D-dimensional de Sitter space is unstable to the nucleation of non-singular geometries containing spacetime regions with different numbers of macroscopic dimensions, leading to a...
Carroll, Sean M., Dulaney, Timothy R., Gresham, Moira I., Tam, Heywood
Theories of low-energy Lorentz violation by a fixed-norm “aether” vector field with two-derivative kinetic terms have a globally bounded Hamiltonian and are perturbatively stable only if the...
Instabilities in the aether (2009)
Carroll, Sean M., Dulaney, Timothy R., Gresham, Moira I., Tam, Heywood
We investigate the stability of theories in which Lorentz invariance is spontaneously broken by fixed-norm vector “aether” fields. Models with generic kinetic terms are plagued either by ghosts...
Implications of a Scalar Dark Force for Terrestrial Experiments (2009)
Carroll, Sean M., Mantry, Sonny, Ramsey-Musolf, Michael J.
A long range Weak Equivalence Principle (WEP) violating force between Dark Matter (DM) particles, mediated by an ultralight scalar, is tightly constrained by galactic dynamics and large scale...
Dark matter and dark radiation (2009)
Ackerman, Lotty, Buckley, Matthew R., Carroll, Sean M., Kamionkowski, Marc
We explore the feasibility and astrophysical consequences of a new long-range U(1) gauge field (“dark electromagnetism”) that couples only to dark matter, not to the standard model. The dark...
Extremal limits and black hole entropy (2009)
Carroll, Sean M., Johnson, Matthew C., Randall, Lisa
Taking the extremal limit of a non-extremal Reissner-Nordstr\"om black hole (by externally varying the mass or charge), the region between the inner and outer event horizons experiences an...
Jamie T. Bridgham, Sean M. Carroll, Joseph W. Thornton
scaled distribution for (A) the SST trend time series and (B) the detrended SST variability time series. Values greater than one (the vertical line in the color bar at the bottom) account for the MI...
A hemispherical power asymmetry from inflation (2008)
Erickcek, Adrienne L., Kamionkowski, Marc, Carroll, Sean M.
Measurements of cosmic microwave background temperature fluctuations by the Wilkinson Microwave Anisotropy Probe indicate that the fluctuation amplitude in one half of the sky differs from the...
Instabilities in the Aether (2008)
Carroll, Sean M., Dulaney, Timothy R., Gresham, Moira I., Tam, Heywood
We investigate the stability of theories in which Lorentz invariance is spontaneously broken by fixed-norm vector "aether" fields. Models with generic kinetic terms are plagued either by ghosts or by...
Carroll, Sean M., Dulaney, Timothy R., Gresham, Moira I., Tam, Heywood
Theories of low-energy Lorentz violation by a fixed-norm "aether" vector field with two-derivative kinetic terms have a globally bounded Hamiltonian and are perturbatively stable only if the vector...
This PDF file includes Materials and Methods (2008)
Jamie T. Bridgham, Sean M. Carroll, Joseph W. Thornton
• Figure S1. Complete maximum likelihood phylogeny of steroid receptors. • Figure S2. Complete BMCMC phylogeny of steroid receptors. • Figure S3. Complete maximum parsimony phylogeny of steroid...
What if Time Really Exists? (2008)
Despite the obvious utility of the concept, it has often been argued that time does not exist. I take the opposite perspective: let's imagine that time does exist, and the universe is described by a...
Translational Invariance and the Anisotropy of the Cosmic Microwave Background (2008)
Carroll, Sean M., Tseng, Chien-Yao, Wise, Mark B.
Primordial quantum fluctuations produced by inflation are conventionally assumed to be statistically homogeneous, a consequence of translational invariance. In this paper we quantify the potentially...
Dark Matter and Dark Radiation (2008)
Ackerman, Lotty, Buckley, Matthew R., Carroll, Sean M., Kamionkowski, Marc
We explore the feasibility and astrophysical consequences of a new long-range U(1) gauge field ("dark electromagnetism") that couples only to dark matter, not to the Standard Model. The dark matter...
Superhorizon perturbations and the cosmic microwave background (2008)
Erickcek, Adrienne L., Carroll, Sean M., Kamionkowski, Marc
Superhorizon perturbations induce large-scale temperature anisotropies in the cosmic microwave background (CMB) via the Grishchuk-Zel'dovich effect. We analyze the CMB temperature anisotropies...
Aether compactification (2008)
Carroll, Sean M., Tam, Heywood
We propose a new way to hide large extra dimensions without invoking branes, based on Lorentz-violating tensor fields with expectation values along the extra directions. We investigate the case of a...
Aether compactification (2008)
Carroll, Sean M., Tam, Heywood
We propose a new way to hide large extra dimensions without invoking branes, based on Lorentz-violating tensor fields with expectation values along the extra directions. We investigate the case of a...
Superhorizon Perturbations and the Cosmic Microwave Background (2008)
Erickcek, Adrienne L., Carroll, Sean M., Kamionkowski, Marc
Superhorizon perturbations induce large-scale temperature anisotropies in the cosmic microwave background (CMB) via the Grishchuk-Zel'dovich effect. We analyze the CMB temperature anisotropies...
Dark-Matter-Induced Weak Equivalence Principle Violation (2008)
Carroll, Sean M., Mantry, Sonny, Ramsey-Musolf, Michael J., Stubbs, Christopher W.
A long-range fifth force coupled to dark matter can induce a coupling to ordinary matter if the dark matter interacts with Standard Model fields. We consider constraints on such a scenario from both...
A Hemispherical Power Asymmetry from Inflation (2008)
Erickcek, Adrienne L., Kamionkowski, Marc, Carroll, Sean M.
Measurements of CMB temperature fluctuations by the Wilkinson Microwave Anisotropy Probe (WMAP) indicate that the fluctuation amplitude in one half of the sky differs from the amplitude in the other...
Aether Compactification (2008)
Carroll, Sean M., Tam, Heywood
We propose a new way to hide extra dimensions without invoking branes, based on Lorentz-violating tensor fields with expectation values along the extra directions. We investigate the case of a single...
Sean M. Carroll, Miguel E. Ortiz
A geometric approach to free variable loop equations in discretized theories of 2D gravity
Imperial/TP/97-98/7 PUPT-1735 (2007)
Sean M. Carroll, Miguel E. Ortiz
hep-th/9711008 Boundary fields and renormalization group flow in the two-matrix model
Theoretical Particle Physics 1995 Progress Report And Research Proposal (2007)
One Of, Edward Farhi, Daniel Freedman, Alan H. Guth, Kerson Huang, Roman Jackiw, ...
this report they completed
Sean M. Carroll, Daniel Freedman, Miguel E. Ortiz, Don N. Page
It is argued that states in N = 1 supergravity that solve all of the constraint equations cannot be bosonic in the sense of being independent of the fermionic degrees of freedom. (Based on a talk...
Lecture Notes on General Relativity (2007)
These notes represent approximately one semester's worth of lectures on introductory general relativity for beginning graduate students in physics. Topics include manifolds, Riemannian geometry,...
Imprints of a primordial preferred direction on the microwave background (2007)
Ackerman, Lotty, Carroll, Sean M., Wise, Mark B.
Rotational invariance is a well-established feature of low-energy physics. Violations of this symmetry must be extremely small today, but could have been larger in earlier epochs. In this paper we...
Imprints of a Primordial Preferred Direction on the Microwave Background (2007)
Ackerman, Lotty, Carroll, Sean M., Wise, Mark B.
Rotational invariance is a well-established feature of low-energy physics. Violations of this symmetry must be extremely small today, but could have been larger in earlier epochs. In this paper we...
Modified-Source Gravity and Cosmological Structure Formation (2006)
Carroll, Sean M., Sawicki, Ignacy, Silvestri, Alessandra, Trodden, Mark
One way to account for the acceleration of the universe is to modify general relativity, rather than introducing dark energy. Typically, such modifications introduce new degrees of freedom. It is...
Is Our Universe Natural? (2005)
It goes without saying that we are stuck with the universe we have. Nevertheless, we would like to go beyond simply describing our observed universe, and try to understand why it is that way rather...
Cosmological Structure Evolution and CMB Anisotropies in DGP Braneworlds (2005)
Sawicki, Ignacy, Carroll, Sean M.
The braneworld model of Dvali, Gabadadze and Porrati (DGP) provides an intriguing modification of gravity at large distances and late times. By embedding a three-brane in an uncompactified extra...
Models of Baryogenesis via Spontaneous Lorentz Violation (2005)
In the presence of background fields that spontaneously violate Lorentz invariance, a matter-antimatter asymmetry can be generated even in thermal equilibrium. In this paper we systematically...
Does Inflation Provide Natural Initial Conditions for the Universe? (2005)
Carroll, Sean M., Chen, Jennifer
If our universe underwent inflation, its entropy during the inflationary phase was substantially lower than it is today. Because a low-entropy state is less likely to be chosen randomly than a...
Spontaneous Inflation and the Origin of the Arrow of Time (2004)
Carroll, Sean M., Chen, Jennifer
We suggest that spontaneous eternal inflation can provide a natural explanation for the thermodynamic arrow of time, and discuss the underlying assumptions and consequences of this view. In the...
The Cosmology of Generalized Modified Gravity Models (2004)
Carroll, Sean M., De Felice, Antonio, Duvvuri, Vikram, Easson, Damien A., Trodden, Mark, Turner, Michael S.
We consider general curvature-invariant modifications of the Einstein-Hilbert action that become important only in regions of extremely low space-time curvature. We investigate the far future...
Can we be tricked into thinking that w is less than -1? (2004)
Carroll, Sean M., De Felice, Antonio, Trodden, Mark
Dark energy candidates for which the equation-of-state parameter w is less than -1 violate the dominant energy condition, and are typically unstable. In scalar-tensor theories of gravity, however,...
Lorentz-Violating Vector Fields Slow the Universe Down (2004)
Carroll, Sean M., Lim, Eugene A.
We consider the gravitational effects of a single, fixed-norm, Lorentz-violating timelike vector field. In a cosmological background, such a vector field acts to rescale the effective value of...
TASI Lectures: Introduction to Cosmology (2004)
Trodden, Mark, Carroll, Sean M.
These proceedings summarize lectures that were delivered as part of the 2002 and 2003 Theoretical Advanced Study Institutes in elementary particle physics (TASI) at the University of Colorado at...
Why is the Universe Accelerating? (2003)
The universe appears to be accelerating, but the reason why is a complete mystery. The simplest explanation, a small vacuum energy (cosmological constant), raises three difficult issues: why the...
Is Cosmic Speed-Up Due to New Gravitational Physics? (2003)
Carroll, Sean M., Duvvuri, Vikram, Trodden, Mark, Turner, Michael S.
We show that cosmic acceleration can arise due to very tiny corrections to the usual gravitational action of General Relativity of the form $R^n$, with $n0$, can lead to early-time inflation, our...
Sidestepping the Cosmological Constant with Football-Shaped Extra Dimensions (2003)
Carroll, Sean M., Guica, Monica M.
We present an exact solution for a factorizable brane-world spacetime with two extra dimensions and explicit brane sources. The compactification manifold has the topology of a two-sphere, and is...
Can the dark energy equation-of-state parameter w be less than -1? (2003)
Carroll, Sean M., Hoffman, Mark, Trodden, Mark
Models of dark energy are conveniently characterized by the equation-of-state parameter w=p/\rho, where \rho is the energy density and p is the pressure. Imposing the Dominant Energy Condition, which...
Akerib, Daniel S., Carroll, Sean M., Kamionkowski, Marc, Ritz, Steven
The past few years have seen dramatic breakthroughs and spectacular and puzzling discoveries in astrophysics and cosmology. In many cases, the new observations can only be explained with the...
Classical Stabilization of Homogeneous Extra Dimensions (2001)
Carroll, Sean M., Geddes, James, Hoffman, Mark B., Wald, Robert M.
If spacetime possesses extra dimensions of size and curvature radii much larger than the Planck or string scales, the dynamics of these extra dimensions should be governed by classical general...
Testing The Friedmann Equation: The Expansion of the Universe During Big-Bang Nucleosynthesis (2001)
Carroll, Sean M., Kaplinghat, Manoj
In conventional general relativity, the expansion rate H of a Robertson-Walker universe is related to the energy density by the Friedmann equation. Aside from the present day, the only epoch at which...
Dark Energy and the Preposterous Universe (2001)
A brief review is offered of the theoretical background concerning dark energy: what is required by observations, what sort of models are being considered, and how they fit into particle physics and...
Noncommutative Field Theory and Lorentz Violation (2001)
Carroll, Sean M., Harvey, Jeffrey A., Kostelecky, V. Alan, Lane, Charles D., Okamoto, Takemi
The role of Lorentz symmetry in noncommutative field theory is considered. Any realistic noncommutative theory is found to be physically equivalent to a subset of a general Lorentz-violating...
Can we live in a self-tuning universe? (2001)
Carroll, Sean M., Mersini, Laura
The self-tuning brane scenario is an attempt to solve the cosmological constant problem in the context of extra dimensions. Rather than making the vacuum energy small, this approach proceeds by...
The Cosmological Constant (2001)
This is a review of the physics and cosmology of the cosmological constant. Focusing on recent developments, I present a pedagogical overview of cosmology in the presence of a cosmological constant,...
The Cosmological Constant (2001)
This is a review of the physics and cosmology of the cosmological constant. Focusing on recent developments, I present a pedagogical overview of cosmology in the presence of a cosmological constant,...
Noncommutative Field Theory and Lorentz Violation (2001)
Carroll, Sean M., Harvey, Jeffrey A., Kostelecký, V. Alan, Lane, Charles D., Okamoto, Takemi
TASI Lectures: Cosmology for String Theorists (2000)
These notes provide a brief introduction to modern cosmology, focusing primarily on theoretical issues. Some attention is paid to aspects of potential interest to students of string theory, on both...
The Cosmological Constant (2000)
This is a review of the physics and cosmology of the cosmological constant. Focusing on recent developments, I present a pedagogical overview of cosmology in the presence of a cosmological constant,...
BPS Domain Wall Junctions in Infinitely Large Extra Dimensions (1999)
Carroll, Sean M., Hellerman, Simeon, Trodden, Mark
We consider models of scalar fields coupled to gravity which are higher-dimensional generalizations of four dimensional supergravity. We use these models to describe domain wall junctions in an...
Domain Wall Junctions are 1/4-BPS States (1999)
Carroll, Sean M., Hellerman, Simeon, Trodden, Mark
We study N=1 SUSY theories in four dimensions with multiple discrete vacua, which admit solitonic solutions describing segments of domain walls meeting at one-dimensional junctions. We show that...
Cosmological Magnetic Fields from Primordial Helicity (1998)
Field, George B., Carroll, Sean M.
Primordial magnetic fields may account for all or part of the fields observed in galaxies. We consider the evolution of the magnetic fields created by pseudoscalar effects in the early universe. Such...
Primordial Magnetic Fields that Last? (1998)
Carroll, Sean M., Field, George B.
The magnetic fields we observe in galaxies today may have their origins in the very early universe. While a number of mechanisms have been proposed which lead to an appreciable field amplitude at...
Quintessence and the Rest of the World (1998)
A nearly-massless, slowly-rolling scalar field $\phi$ may provide most of the energy density of the current universe. One potential difficulty with this idea is that couplings to ordinary matter,...
Lecture Notes on General Relativity (1997)
These notes represent approximately one semester's worth of lectures on introductory general relativity for beginning graduate students in physics. Topics include manifolds, Riemannian geometry,...
Dark Matter with Time-Dependent Mass (1997)
Anderson, Greg W., Carroll, Sean M.
We propose a simple model in which the cosmological dark matter consists of particles whose mass increases with the scale factor of the universe. The particle mass is generated by the expectation...
Dirichlet Topological Defects (1997)
Carroll, Sean M., Trodden, Mark
We propose a class of field theories featuring solitonic solutions in which topological defects can end when they intersect other defects of equal or higher dimensionality. Such configurations may be...
Is there evidence for cosmic anisotropy in the polarization of distant radio sources? (1997)
Carroll, Sean M., Field, George B.
Measurements of the polarization angle and orientation of cosmological radio sources may be used to search for unusual effects in the propagation of light through the universe. Recently, Nodland and...
The Collapse of Exotic Textures (1997)
Sornborger, Andrew, Carroll, Sean M., Pyne, Ted
The ordering of scalar fields after a phase transition in which a group $G$ of global symmetries is spontaneously broken to a subgroup $H$ provides a possible explanation for the origin of structure...
Lecture Notes on General Relativity (1997)
These notes represent approximately one semester's worth of lectures on introductory general relativity for beginning graduate students in physics. Topics include manifolds, Riemannian geometry,...
The Ising model with a boundary magnetic field on a random surface (1996)
Carroll, Sean M., Ortiz, Miguel E., Taylor IV, Washington
The bulk and boundary magnetizations are calculated for the critical Ising model on a randomly triangulated disk in the presence of a boundary magnetic field h. In the continuum limit this model...
Thesis (M.S. - Hydrology and Water Resources)--University of Arizona.
Spin/disorder correlations and duality in the c=1/2 string (1995)
Carroll, Sean M., Ortiz, Miguel E., Taylor IV, Washington
We use the method of discrete loop equations to calculate exact correlation functions of spin and disorder operators on the sphere and on the boundary of a disk in the $c = 1/2$ string, both in the...
A geometric approach to free variable loop equations in discretized theories of 2D gravity (1995)
Carroll, Sean M., Ortiz, Miguel E., Taylor IV, Washington
We present a self-contained analysis of theories of discrete 2D gravity coupled to matter, using geometric methods to derive equations for generating functions in terms of free (noncommuting)...
Higher-Order Gravitational Perturbations of the Cosmic Microwave Background (1995)
We study the behavior of light rays in perturbed Robertson-Walker cosmologies, calculating the redshift between an observer and the surface of last scattering to second order in the metric...
Energy-Momentum Restrictions on the Creation of Gott Time Machines (1994)
Carroll, Sean M., Farhi, Edward, Guth, Alan H., Olum, Ken D.
The discovery by Gott of a remarkably simple spacetime with closed timelike curves (CTC's) provides a tool for investigating how the creation of time machines is prevented in classical general...
Consequences of Propagating Torsion in Connection-Dynamic Theories of Gravity (1994)
Carroll, Sean M., Field, George B.
We discuss the possibility of constraining theories of gravity in which the connection is a fundamental variable by searching for observational consequences of the torsion degrees of freedom. In a...
Physical States in Canonically Quantized Supergravity (1994)
Carroll, Sean M., Freedman, Daniel Z., Ortiz, Miguel E., Page, Don N.
We discuss the canonical quantization of $N=1$ supergravity in the functional Schrodinger representation. Although the form of the supersymmetry constraints suggests that there are solutions of...
Physical States In Canonically Quantized Supergravity (1994)
Sean M. Carroll, Daniel Z. Freedman, Miguel E. Ortiz
We discuss the canonical quantization of N = 1 supergravity in the functional Schrodinger representation. Although the form of the supersymmetry constraints suggests that there are solutions of...
Bryan, James A., Carroll, Sean M., Pyne, Ted
Textures are topologically nontrivial field configurations which can exist in a field theory in which a global symmetry group $G$ is broken to a subgroup $H$, if the third homotopy group $\p3$ of...
Primordial magnetic fields from pseudo-Goldstone bosons (1992)
Garretson, W. Daniel, Field, George B., Carroll, Sean M.
The existence of large-scale magnetic fields in galaxies is well established, but there is no accepted mechanism for generating a primordial field which could grow into what is observed today. We...
Carroll, Sean M., Farhi, Edward, Guth, Alan H.
We prove the title.
Cosmological limits on Chern-Simons electromagnetism / (1990)
Research examination (Ph. D.)--Harvard University, 1990.