D. Baumann - EPIC Collaboration

D. Baumann
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D. Baumann
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EPIC Collaboration
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Cosmology and Nongalactic Astrophysics (39)
 
High Energy Physics - Theory (31)
 
High Energy Physics - Phenomenology (25)
 
General Relativity and Quantum Cosmology (9)
 
Nuclear Experiment (6)
 
Physics - Superconductivity (4)
 
Instrumentation and Methods for Astrophysics (3)
 
Physics - Materials Science (1)
 
Physics - Strongly Correlated Electrons (1)
 
Physics - Chemical Physics (1)
 
Physics - Disordered Systems and Neural Networks (1)
 
Astrophysics of Galaxies (1)
 
Physics - Instrumentation and Detectors (1)
 
High Energy Physics - Experiment (1)

Publications Authored By D. Baumann

A new Short-Orbit Spectrometer (SOS) has been constructed and installed within the experimental facility of the A1 collaboration at Mainz Microtron (MAMI), with the goal to detect low-energy pions. It is equipped with a Browne-Buechner magnet and a detector system consisting of two helium-ethane based drift chambers and a scintillator telescope made of five layers. The detector system allows detection of pions in the momentum range of 50 - 147 MeV/c, which corresponds to 8. Read More

2017Apr
Authors: M. Remazeilles, A. J. Banday, C. Baccigalupi, S. Basak, A. Bonaldi, G. De Zotti, J. Delabrouille, C. Dickinson, H. K. Eriksen, J. Errard, R. Fernandez-Cobos, U. Fuskeland, C. Hervías-Caimapo, M. López-Caniego, E. Martinez-González, M. Roman, P. Vielva, I. Wehus, A. Achucarro, P. Ade, R. Allison, M. Ashdown, M. Ballardini, R. Banerji, N. Bartolo, J. Bartlett, D. Baumann, M. Bersanelli, M. Bonato, J. Borrill, F. Bouchet, F. Boulanger, T. Brinckmann, M. Bucher, C. Burigana, A. Buzzelli, Z. -Y. Cai, M. Calvo, C. -S. Carvalho, G. Castellano, A. Challinor, J. Chluba, S. Clesse, I. Colantoni, A. Coppolecchia, M. Crook, G. D'Alessandro, P. de Bernardis, G. de Gasperis, J. -M. Diego, E. Di Valentino, S. Feeney, S. Ferraro, F. Finelli, F. Forastieri, S. Galli, R. Genova-Santos, M. Gerbino, J. González-Nuevo, S. Grandis, J. Greenslade, S. Hagstotz, S. Hanany, W. Handley, C. Hernandez-Monteagudo, M. Hills, E. Hivon, K. Kiiveri, T. Kisner, T. Kitching, M. Kunz, H. Kurki-Suonio, L. Lamagna, A. Lasenby, M. Lattanzi, J. Lesgourgues, A. Lewis, M. Liguori, V. Lindholm, G. Luzzi, B. Maffei, C. J. A. P. Martins, S. Masi, D. McCarthy, J. -B. Melin, A. Melchiorri, D. Molinari, A. Monfardini, P. Natoli, M. Negrello, A. Notari, A. Paiella, D. Paoletti, G. Patanchon, M. Piat, G. Pisano, L. Polastri, G. Polenta, A. Pollo, V. Poulin, M. Quartin, J. -A. Rubino-Martin, L. Salvati, A. Tartari, M. Tomasi, D. Tramonte, N. Trappe, T. Trombetti, C. Tucker, J. Valiviita, R. Van de Weijgaert, B. van Tent, V. Vennin, N. Vittorio, K. Young, for the CORE collaboration

We demonstrate that, for the baseline design of the CORE satellite mission, the polarized foregrounds can be controlled at the level required to allow the detection of the primordial cosmic microwave background (CMB) $B$-mode polarization with the desired accuracy at both reionization and recombination scales, for tensor-to-scalar ratio values of $r\gtrsim 5\times 10^{-3}$. Under the assumption of perfect control of lensing effects, CORE would measure an unbiased estimate of $r=5\times 10^{-3}$ with an uncertainty of ${\sigma(r=5\times 10^{-3})=0.4\times 10^{-3}}$ after foreground cleaning. Read More

2017Mar
Authors: J. -B. Melin, A. Bonaldi, M. Remazeilles, S. Hagstotz, J. M. Diego, C. Hernández-Monteagudo, R. T. Génova-Santos, G. Luzzi, C. J. A. P. Martins, S. Grandis, J. J. Mohr, J. G. Bartlett, J. Delabrouille, S. Ferraro, D. Tramonte, J. A. Rubiño-Martín, J. F. Macìas-Pérez, A. Achúcarro, P. Ade, R. Allison, M. Ashdown, M. Ballardini, A. J. Banday, R. Banerji, N. Bartolo, S. Basak, J. Baselmans, K. Basu, R. A. Battye, D. Baumann, M. Bersanelli, M. Bonato, J. Borrill, F. Bouchet, F. Boulanger, T. Brinckmann, M. Bucher, C. Burigana, A. Buzzelli, Z. -Y. Cai, M. Calvo, C. S. Carvalho, M. G. Castellano, A. Challinor, J. Chluba, S. Clesse, S. Colafrancesco, I. Colantoni, A. Coppolecchia, M. Crook, G. D'Alessandro, P. de Bernardis, G. de Gasperis, M. De Petris, G. De Zotti, E. Di Valentino, J. Errard, S. M. Feeney, R. Fernández-Cobos, F. Finelli, F. Forastieri, S. Galli, M. Gerbino, J. González-Nuevo, J. Greenslade, S. Hanany, W. Handley, C. Hervias-Caimapo, M. Hills, E. Hivon, K. Kiiveri, T. Kisner, T. Kitching, M. Kunz, H. Kurki-Suonio, L. Lamagna, A. Lasenby, M. Lattanzi, A. M. C. Le Brun, J. Lesgourgues, A. Lewis, M. Liguori, V. Lindholm, M. Lopez-Caniego, B. Maffei, E. Martinez-Gonzalez, S. Masi, D. McCarthy, A. Melchiorri, D. Molinari, A. Monfardini, P. Natoli, M. Negrello, A. Notari, A. Paiella, D. Paoletti, G. Patanchon, M. Piat, G. Pisano, L. Polastri, G. Polenta, A. Pollo, V. Poulin, M. Quartin, M. Roman, L. Salvati, A. Tartari, M. Tomasi, N. Trappe, S. Triqueneaux, T. Trombetti, C. Tucker, J. Väliviita, R. van de Weygaert, B. Van Tent, V. Vennin, P. Vielva, N. Vittorio, J. Weller, K. Young, M. Zannoni, for the CORE collaboration

We examine the cosmological constraints that can be achieved with a galaxy cluster survey with the future CORE space mission. Using realistic simulations of the millimeter sky, produced with the latest version of the Planck Sky Model, we characterize the CORE cluster catalogues as a function of the main mission performance parameters. We pay particular attention to telescope size, key to improved angular resolution, and discuss the comparison and the complementarity of CORE with ambitious future ground-based CMB experiments that could be deployed in the next decade. Read More

We show that the phase of the spectrum of baryon acoustic oscillations (BAO) is immune to the effects of nonlinear evolution. This suggests that any new physics that contributes to the initial phase of the BAO spectrum, such as extra light species in the early universe, can be extracted reliably at late times. We provide three arguments in support of our claim: First, we point out that a phase shift of the BAO spectrum maps to a characteristic sign change in the real space correlation function and that this feature cannot be generated or modified by nonlinear dynamics. Read More

2016Dec
Authors: CORE Collaboration, Fabio Finelli, Martin Bucher, Ana Achúcarro, Mario Ballardini, Nicola Bartolo, Daniel Baumann, Sébastien Clesse, Josquin Errard, Will Handley, Mark Hindmarsh, Kimmo Kiiveri, Martin Kunz, Anthony Lasenby, Michele Liguori, Daniela Paoletti, Christophe Ringeval, Jussi Väliviita, Bartjan van Tent, Vincent Vennin, Rupert Allison, Frederico Arroja, Marc Ashdown, A. J. Banday, Ranajoy Banerji, James G. Bartlett, Soumen Basak, Jochem Baselmans, Paolo de Bernardis, Marco Bersanelli, Anna Bonaldi, Julian Borril, François R. Bouchet, François Boulanger, Thejs Brinckmann, Carlo Burigana, Alessandro Buzzelli, Zhen-Yi Cai, Martino Calvo, Carla Sofia Carvalho, Gabriella Castellano, Anthony Challinor, Jens Chluba, Ivan Colantoni, Martin Crook, Giuseppe D'Alessandro, Guido D'Amico, Jacques Delabrouille, Vincent Desjacques, Gianfranco De Zotti, Jose Maria Diego, Eleonora Di Valentino, Stephen Feeney, James R. Fergusson, Raul Fernandez-Cobos, Simone Ferraro, Francesco Forastieri, Silvia Galli, Juan García-Bellido, Giancarlo de Gasperis, Ricardo T. Génova-Santos, Martina Gerbino, Joaquin González-Nuevo, Sebastian Grandis, Josh Greenslade, Steffen Hagstotz, Shaul Hanany, Dhiraj K. Hazra, Carlos Hernández-Monteagudo, Carlos Hervias-Caimapo, Matthew Hills, Eric Hivon, Bin Hu, Ted Kisner, Thomas Kitching, Ely D. Kovetz, Hannu Kurki-Suonio, Luca Lamagna, Massimiliano Lattanzi, Julien Lesgourgues, Antony Lewis, Valtteri Lindholm, Joanes Lizarraga, Marcos López-Caniego, Gemma Luzzi, Bruno Maffei, Nazzareno Mandolesi, Enrique Martínez-González, Carlos J. A. P. Martins, Silvia Masi, Darragh McCarthy, Sabino Matarrese, Alessandro Melchiorri, Jean-Baptiste Melin, Diego Molinari, Alessandro Monfardini, Paolo Natoli, Mattia Negrello, Alessio Notari, Filippo Oppizzi, Alessandro Paiella, Enrico Pajer, Guillaume Patanchon, Subodh P. Patil, Michael Piat, Giampaolo Pisano, Linda Polastri, Gianluca Polenta, Agnieszka Pollo, Vivian Poulin, Miguel Quartin, Andrea Ravenni, Mathieu Remazeilles, Alessandro Renzi, Diederik Roest, Matthieu Roman, Jose Alberto Rubiño-Martin, Laura Salvati, Alexei A. Starobinsky, Andrea Tartari, Gianmassimo Tasinato, Maurizio Tomasi, Jesús Torrado, Neil Trappe, Tiziana Trombetti, Carole Tucker, Marco Tucci, Jon Urrestilla, Rien van de Weygaert, Patricio Vielva, Nicola Vittorio, Karl Young

We forecast the scientific capabilities to improve our understanding of cosmic inflation of CORE, a proposed CMB space satellite submitted in response to the ESA fifth call for a medium-size mission opportunity. The CORE satellite will map the CMB anisotropies in temperature and polarization in 19 frequency channels spanning the range 60-600 GHz. CORE will have an aggregate noise sensitivity of $1. Read More

2016Nov
Authors: Eleonora Di Valentino, Thejs Brinckmann, Martina Gerbino, Vivian Poulin, François R. Bouchet, Julien Lesgourgues, Alessandro Melchiorri, Jens Chluba, Sebastien Clesse, Jacques Delabrouille, Cora Dvorkin, Francesco Forastieri, Silvia Galli, Deanna C. Hooper, Massimiliano Lattanzi, Carlos J. A. P. Martins, Laura Salvati, Giovanni Cabass, Andrea Caputo, Elena Giusarma, Eric Hivon, Paolo Natoli, Luca Pagano, Simone Paradiso, Jose Alberto Rubino-Martin, Ana Achucarro, Peter Ade, Rupert Allison, Frederico Arroja, Marc Ashdown, Mario Ballardini, A. J. Banday, Ranajoy Banerji, Nicola Bartolo, James G. Bartlett, Soumen Basak, Jochem Baselmans, Daniel Baumann, Paolo de Bernardis, Marco Bersanelli, Anna Bonaldi, Matteo Bonato, Julian Borrill, François Boulanger, Martin Bucher, Carlo Burigana, Alessandro Buzzelli, Zhen-Yi Cai, Martino Calvo, Carla Sofia Carvalho, Gabriella Castellano, Anthony Challinor, Ivan Charles, Ivan Colantoni, Alessandro Coppolecchia, Martin Crook, Giuseppe D'Alessandro, Marco De Petris, Gianfranco De Zotti, Josè Maria Diego, Josquin Errard, Stephen Feeney, Raul Fernandez-Cobos, Simone Ferraro, Fabio Finelli, Giancarlo de Gasperis, Ricardo T. Génova-Santos, Joaquin González-Nuevo, Sebastian Grandis, Josh Greenslade, Steffen Hagstotz, Shaul Hanany, Will Handley, Dhiraj K. Hazra, Carlos Hernández-Monteagudo, Carlos Hervias-Caimapo, Matthew Hills, Kimmo Kiiveri, Ted Kisner, Thomas Kitching, Martin Kunz, Hannu Kurki-Suonio, Luca Lamagna, Anthony Lasenby, Antony Lewis, Michele Liguori, Valtteri Lindholm, Marcos Lopez-Caniego, Gemma Luzzi, Bruno Maffei, Sylvain Martin, Enrique Martinez-Gonzalez, Silvia Masi, Darragh McCarthy, Jean-Baptiste Melin, Joseph J. Mohr, Diego Molinari, Alessandro Monfardini, Mattia Negrello, Alessio Notari, Alessandro Paiella, Daniela Paoletti, Guillaume Patanchon, Francesco Piacentini, Michael Piat, Giampaolo Pisano, Linda Polastri, Gianluca Polenta, Agnieszka Pollo, Miguel Quartin, Mathieu Remazeilles, Matthieu Roman, Christophe Ringeval, Andrea Tartari, Maurizio Tomasi, Denis Tramonte, Neil Trappe, Tiziana Trombetti, Carole Tucker, Jussi Väliviita, Rien van de Weygaert, Bartjan Van Tent, Vincent Vennin, Gérard Vermeulen, Patricio Vielva, Nicola Vittorio, Karl Young, Mario Zannoni, for the CORE collaboration

We forecast the main cosmological parameter constraints achievable with the CORE space mission which is dedicated to mapping the polarisation of the Cosmic Microwave Background (CMB). CORE was recently submitted in response to ESA's fifth call for medium-sized mission proposals (M5). Here we report the results from our pre-submission study of the impact of various instrumental options, in particular the telescope size and sensitivity level, and review the great, transformative potential of the mission as proposed. Read More

We study the imprints of massive particles with spin on cosmological correlators. Using the framework of the effective field theory of inflation, we classify the couplings of these particles to the Goldstone boson of broken time translations and the graviton. We show that it is possible to generate observable non-Gaussianity within the regime of validity of the effective theory, as long as the masses of the particles are close to the Hubble scale and their interactions break the approximate conformal symmetry of the inflationary background. Read More

The cross section of the $p(e,e'\pi^+)n$ reaction has been measured for five kinematic settings at an invariant mass of $W = 1094$ MeV and for a four-momentum transfer of $Q^2 = 0.078$ (GeV/$c$)$^2$. The measurement has been performed at MAMI using a new short-orbit spectrometer (SOS) of the A1 collaboration, intended for detection of low-energy pions. Read More

Future CMB experiments have the potential to probe the density of relativistic species at the sub-percent level. Sensitivity at this level allows light thermal relics to be detected up to arbitrarily high decoupling temperatures. Conversely, the absence of a detection would require extra light species never to have been in equilibrium with the Standard Model. Read More

We present a microscopic investigation of frequently observed impurity-induced states in stoichiometric LiFeAs using low temperature scanning tunneling microscopy and spectroscopy (STM/STS). Our data reveal seven distinct well defined defects which are discernible in topographic measurements. Depending on their local topographic symmetry, we are able to assign five defect types to specific lattice sites at the Li, Fe and As positions. Read More

We provide a statistical framework for characterizing stochastic particle production in the early universe via a precise correspondence to current conduction in wires with impurities. Our approach is particularly useful when the microphysics is uncertain and the dynamics are complex, but only coarse-grained information is of interest. We study scenarios with multiple interacting fields and derive the evolution of the particle occupation numbers from a Fokker-Planck equation. Read More

We present a systematic study of galaxy biasing in the presence of primordial non-Gaussianity. For a large class of non-Gaussian initial conditions, we define a general bias expansion and prove that it is closed under renormalization, thereby showing that the basis of operators in the expansion is complete. We then study the effects of primordial non-Gaussianity on the statistics of galaxies. Read More

We have performed temperature dependent tunneling spectroscopy on an impurity-free surface area of a LiFeAs single crystal. Our data reveal a highly unusual temperature evolution of superconductivity: at $T_c^*=18$~K a partial superconducting gap opens, as is evidenced by subtle, yet clear features in the tunneling spectra, i.e. Read More

Fluctuations in the cosmic neutrino background are known to produce a phase shift in the acoustic peaks of the cosmic microwave background. It is through the sensitivity to this effect that the recent CMB data has provided a robust detection of free-streaming neutrinos. In this paper, we revisit the phase shift of the CMB anisotropy spectrum as a probe of new physics. Read More

In this paper, we explore a novel observational signature of gravitational corrections during slow-roll inflation. We study the coupling of the inflaton field to higher-curvature tensors in models with a minimal breaking of conformal symmetry. In that case, the most general correction to the tensor two-point function is captured by a coupling to the square of the Weyl tensor. Read More

We develop the effective theory of large-scale structure for non-Gaussian initial conditions. The effective stress tensor in the dark matter equations of motion contains new operators, which originate from the squeezed limit of the primordial bispectrum. Parameterizing the squeezed limit by a scaling and an angular dependence, captures large classes of primordial non-Gaussianity. Read More

The analyticity of response functions and scattering amplitudes implies powerful relations between low-energy observables and the underlying short-distance dynamics. These 'IR/UV' relations are rooted in basic physical principles, such as causality and unitarity. In this paper, we seek similar connections in inflation, relating cosmological observations to the physics responsible for the accelerated expansion. Read More

Inflation predicts B-mode polarization with correlations that span superhorizon scales at recombination. In contrast, the correlations set up by causal sources, such as phase transitions or defects, necessarily vanish on superhorizon scales. Motivated by BICEP2's B-mode detection, we consider the prospects for measuring the inflationary superhorizon signature in future observations. Read More

Observations of the cosmic microwave background do not yet determine whether inflation was driven by a slowly-rolling scalar field or involved another physical mechanism. In this paper we discuss the prospects of using the power spectra of scalar and tensor modes to probe the nature of inflation. We focus on the leading modification to the slow-roll dynamics, which entails a sound speed $c_s$ for the scalar fluctuations. Read More

We present microscopic investigations on the two-dimensional arrangement of cobalt phthalocyanine molecules on a graphite (HOPG) substrate in the low coverage regime. The initial growth and ordering of molecular layers is revealed in high resolution scanning tunneling microscopy (STM). On low coverages single molecules orient mostly along one of the substrate lattice directions, while they form chains at slightly higher coverage. Read More

We review cosmological inflation and its realization in quantum field theory and in string theory. This material is a portion of a book, also entitled "Inflation and String Theory", to be published by Cambridge University Press. Read More

This paper provides a systematic study of renormalization in models of halo biasing. Building on work of McDonald, we show that Eulerian biasing is only consistent with renormalization if non-local terms and higher-derivative contributions are included in the biasing model. We explicitly determine the complete list of required bias parameters for Gaussian initial conditions, up to quartic order in the dark matter density contrast and at leading order in derivatives. Read More

We report new p$(\vec{e},e^\prime p)\pi^\circ$ measurements in the $\Delta^{+}(1232)$ resonance at the low momentum transfer region utilizing the magnetic spectrometers of the A1 Collaboration at MAMI. The mesonic cloud dynamics are predicted to be dominant and appreciably changing in this region while the momentum transfer is sufficiently low to be able to test chiral effective calculations. The results disagree with predictions of constituent quark models and are in reasonable agreement with dynamical calculations with pion cloud effects, chiral effective field theory and lattice calculations. Read More

We show that the recent Planck limits on primordial non-Gaussianity impose strong constraints on light hidden sector fields coupled to the inflaton via operators suppressed by a high mass scale \Lambda. We study a simple effective field theory in which a hidden sector field is coupled to a shift-symmetric inflaton via arbitrary operators up to dimension five. Self-interactions in the hidden sector lead to non-Gaussianity in the curvature perturbations. Read More

Several angle resolved photoemission spectroscopy (ARPES) studies reveal a poorly nested Fermi surface of LiFeAs, far away from a spin density wave instability, and clear-cut superconducting gap anisotropies. On the other hand a very different, more nested Fermi surface and dissimilar gap anisotropies have been obtained from quasiparticle interference (QPI) data, which were interpreted as arising from intraband scattering within hole-like bands. Here we show that this ARPES-QPI paradox is completely resolved by interband scattering between the hole-like bands. Read More

In this paper, we prove that the superhorizon conservation of the curvature perturbation zeta in single-field inflation holds as an operator statement. This implies that all zeta-correlators are time independent at all orders in the loop expansion. Our result follows directly from locality and diffeomorphism invariance of the underlying theory. Read More

In this article, we show that a stochastic form of scale-dependent halo bias arises in multi-source inflationary models, where multiple fields determine the initial curvature perturbation. We derive this effect for general non-Gaussian initial conditions and study various examples, such as curvaton models and quasi-single field inflation. We present a general formula for both the stochastic and the non-stochastic parts of the halo bias, in terms of the N-point cumulants of the curvature perturbation at the end of inflation. Read More

Several, apparently distinct, formalisms exist in the literature for predicting the clustering of dark matter halos. It has been noticed on a case-by-case basis that the predictions of these different methods agree in specific examples, but there is no general proof that they are equivalent. In this paper, we give a simple proof of the mathematical equivalence of barrier crossing, peak-background split, and local biasing. Read More

Soft limits of inflationary correlation functions are both observationally relevant and theoretically robust. Various theorems can be proven about them that are insensitive to detailed model-building assumptions. In this paper, we re-derive several of these theorems in a universal way. Read More

We explore the consequences of a detection of primordial tensor fluctuations for general single-field models of inflation. Using the effective theory of inflation, we propose a generalization of the Lyth bound. Our bound applies to all single-field models with two-derivative kinetic terms for the scalar fluctuations and is always stronger than the corresponding bound for slow-roll models. Read More

Supersymmetry plays a fundamental role in the radiative stability of many inflationary models. Spontaneous breaking of the symmetry inevitably leads to fields with masses of order the Hubble scale during inflation. When these fields couple to the inflaton they produce a unique signature in the squeezed limit of the three-point function of primordial curvature perturbations. Read More

Higher-derivative operators are central elements of any effective field theory. In supersymmetric theories, these operators include terms with derivatives in the K\"ahler potential. We develop a toolkit for coupling such supersymmetric effective field theories to supergravity. Read More

A crucial step in revealing the nature of unconventional superconductivity is to investigate the symmetry of the superconducting order parameter. Scanning tunneling spectroscopy has proven a powerful technique to probe this symmetry by measuring the quasiparticle interference (QPI) which sensitively depends on the superconducting pairing mechanism. A particularly well suited material to apply this technique is the stoichiometric superconductor LiFeAs as it features clean, charge neutral cleaved surfaces without surface states and a relatively high Tc~18K. Read More

We examine the effective theory of single-field inflation in the limit where the scalar perturbations propagate with a small speed of sound. In this case the non-linearly realized time-translation symmetry of the Lagrangian implies large interactions, giving rise to primordial non-Gaussianities. When the non-Gaussianities are measurable, these interactions will become strongly coupled unless new physics appears close to the Hubble scale. Read More

The effective theory of adiabatic fluctuations around arbitrary Friedmann-Robertson-Walker backgrounds - both expanding and contracting - allows for more than one way to obtain scale-invariant two-point correlations. However, as we show in this paper, it is challenging to produce scale-invariant fluctuations that are weakly coupled over the range of wavelengths accessible to cosmological observations. In particular, requiring the background to be a dynamical attractor, the curvature fluctuations are scale-invariant and weakly coupled for at least 10 e-folds only if the background is close to de Sitter space. Read More

We present a field theory solution to the eta problem. By making the inflaton field the phase of a baryon of SU(N_c) supersymmetric Yang-Mills theory we show that all operators that usually spoil the flatness of the inflationary potential are absent. Our solution naturally generalizes to non-supersymmetric theories. Read More

A new mechanism to control Planck-scale corrections to the inflationary eta parameter is proposed. A common approach to the eta problem is to impose a shift symmetry on the inflaton field. However, this symmetry has to remain unbroken by Planck-scale effects, which is a rather strong requirement on possible ultraviolet completions of the theory. Read More

The universe is smooth on large scales but very inhomogeneous on small scales. Why is the spacetime on large scales modeled to a good approximation by the Friedmann equations? Are we sure that small-scale non-linearities do not induce a large backreaction? Related to this, what is the effective theory that describes the universe on large scales? In this paper we make progress in addressing these questions. We show that the effective theory for the long-wavelength universe behaves as a viscous fluid coupled to gravity: integrating out short-wavelength perturbations renormalizes the homogeneous background and introduces dissipative dynamics into the evolution of long-wavelength perturbations. Read More

We give a comprehensive treatment of the scalar potential for a D3-brane in a warped conifold region of a compactification with stabilized moduli. By studying general ultraviolet perturbations in supergravity, we systematically incorporate `compactification effects' sourced by supersymmetry breaking in the compact space. Significant contributions to the D3-brane potential, including the leading term in the infrared, arise from imaginary anti-self-dual (IASD) fluxes. Read More

We determine the scalar potential for a D3-brane in a warped conifold background subject to general ultraviolet perturbations. Incorporating the effects of imaginary anti-self-dual (IASD) fluxes and four-dimensional curvature at the nonlinear level, we compute the leading terms in the D3-brane potential. We then provide strong cross-checks of our results by reproducing them in the dual gauge theory. Read More

In a series of five lectures I review inflationary cosmology. I begin with a description of the initial conditions problems of the Friedmann-Robertson-Walker (FRW) cosmology and then explain how inflation, an early period of accelerated expansion, solves these problems. Next, I describe how inflation transforms microscopic quantum fluctuations into macroscopic seeds for cosmological structure formation. Read More

2009Jun
Affiliations: 1EPIC Collaboration, 2EPIC Collaboration, 3EPIC Collaboration, 4EPIC Collaboration, 5EPIC Collaboration, 6EPIC Collaboration, 7EPIC Collaboration, 8EPIC Collaboration, 9EPIC Collaboration, 10EPIC Collaboration, 11EPIC Collaboration, 12EPIC Collaboration, 13EPIC Collaboration, 14EPIC Collaboration, 15EPIC Collaboration, 16EPIC Collaboration, 17EPIC Collaboration, 18EPIC Collaboration, 19EPIC Collaboration, 20EPIC Collaboration, 21EPIC Collaboration, 22EPIC Collaboration, 23EPIC Collaboration, 24EPIC Collaboration, 25EPIC Collaboration, 26EPIC Collaboration, 27EPIC Collaboration, 28EPIC Collaboration, 29EPIC Collaboration, 30EPIC Collaboration, 31EPIC Collaboration, 32EPIC Collaboration, 33EPIC Collaboration, 34EPIC Collaboration, 35EPIC Collaboration, 36EPIC Collaboration, 37EPIC Collaboration, 38EPIC Collaboration

Measurements of Cosmic Microwave Background (CMB) anisotropy have served as the best experimental probe of the early universe to date. The inflationary paradigm, inspired in part by the extreme isotropy of the CMB, is now a cornerstone in modern cosmology. Inflation has passed a series of rigorous experimental tests, but we still do not understand the physical mechanism or energy scale behind inflation. Read More

We investigate recent claims that brane inflation solves the overshoot problem through a combination of microphysical restrictions on the phase space of initial conditions and the existence of the Dirac-Born-Infeld (DBI) attractor in regimes where the slow-roll attractor does not apply. Carrying out a comprehensive analysis of the parameter space allowed by the latest advances in brane inflation model-building, we find that these restrictions are insufficient to solve the overshoot problem. The vast majority of the phase space of initial conditions is still dominated by overshoot trajectories. Read More

Cross sections for the ^{3}He(e,e'pn)p reaction were measured for the first time at energy transfers of 220 and 270 MeV for several momentum transfers ranging from 300 to 450 MeV/c. Cross sections are presented as a function of the momentum of the recoil proton and the momentum transfer. Continuum Faddeev calculations using the Argonne V18 and Bonn-B nucleon-nucleon potentials overestimate the measured cross sections by a factor 5 at low recoil proton momentum with the discrepancy becoming much smaller at higher recoil momentum. Read More

Modern cosmology has sharpened questions posed for millennia about the origin of our cosmic habitat. The age-old questions have been transformed into two pressing issues primed for attack in the coming decade: How did the Universe begin? and What physical laws govern the Universe at the highest energies? The clearest window onto these questions is the pattern of polarization in the Cosmic Microwave Background (CMB), which is uniquely sensitive to primordial gravity waves. A detection of the special pattern produced by gravity waves would be not only an unprecedented discovery, but also a direct probe of physics at the earliest observable instants of our Universe. Read More

We introduce the real space correlation function of $B$-mode polarization of the cosmic microwave background (CMB) as a probe of superhorizon tensor perturbations created by inflation. By causality, any non-inflationary mechanism for gravitational wave production after reheating, like global phase transitions or cosmic strings, must have vanishing correlations for angular separations greater than the angle subtended by the particle horizon at recombination, i.e. Read More

We provide a pedagogical overview of inflation in string theory. Our theme is the sensitivity of inflation to Planck-scale physics, which we argue provides both the primary motivation and the central theoretical challenge for the subject. We illustrate these issues through two case studies of inflationary scenarios in string theory: warped D-brane inflation and axion monodromy inflation. Read More