Radiative corrections from heavy fast-roll fields during inflation
Jain, Rajeev Kumar; Sandora, McCullen; Sloth, Martin S.
2015-06-09
We investigate radiative corrections to the inflaton potential from heavy fields undergoing a fast-roll phase transition. We find that a logarithmic one-loop correction to the inflaton potential involving this field can induce a temporary running of the spectral index. The induced running can be a short burst of strong running, which may be related to the observed anomalies on large scales in the cosmic microwave spectrum, or extend over many e-folds, sustaining an effectively constant running to be searched for in the future. We implement this in a general class of models, where effects are mediated through a heavy messenger field sitting in its minimum. Interestingly, within the present framework it is a generic outcome that a large running implies a small field model with a vanishing tensor-to-scalar ratio, circumventing the normal expectation that small field models typically lead to an unobservably small running of the spectral index. An observable level of tensor modes can also be accommodated, but, surprisingly, this requires running to be induced by a curvaton. If upcoming observations are consistent with a small tensor-to-scalar ratio as predicted by small field models of inflation, then the present study serves as an explicit example contrary to the general expectation that the running will be unobservable.
Radiative corrections from heavy fast-roll fields during inflation
Jain, Rajeev Kumar; Sandora, McCullen; Sloth, Martin S. E-mail: sandora@cp3.dias.sdu.dk
2015-06-01
We investigate radiative corrections to the inflaton potential from heavy fields undergoing a fast-roll phase transition. We find that a logarithmic one-loop correction to the inflaton potential involving this field can induce a temporary running of the spectral index. The induced running can be a short burst of strong running, which may be related to the observed anomalies on large scales in the cosmic microwave spectrum, or extend over many e-folds, sustaining an effectively constant running to be searched for in the future. We implement this in a general class of models, where effects are mediated through a heavy messenger field sitting in its minimum. Interestingly, within the present framework it is a generic outcome that a large running implies a small field model with a vanishing tensor-to-scalar ratio, circumventing the normal expectation that small field models typically lead to an unobservably small running of the spectral index. An observable level of tensor modes can also be accommodated, but, surprisingly, this requires running to be induced by a curvaton. If upcoming observations are consistent with a small tensor-to-scalar ratio as predicted by small field models of inflation, then the present study serves as an explicit example contrary to the general expectation that the running will be unobservable.
CMB quadrupole suppression. II. The early fast roll stage
NASA Astrophysics Data System (ADS)
Boyanovsky, D.; de Vega, H. J.; Sanchez, N. G.
2006-12-01
Within the effective field theory of inflation, an initialization of the classical dynamics of the inflaton with approximate equipartition between the kinetic and potential energy of the inflaton leads to a brief fast roll stage that precedes the slow roll regime. The fast roll stage leads to an attractive potential in the wave equations for the mode functions of curvature and tensor perturbations. The evolution of the inflationary perturbations is equivalent to the scattering by this potential and a useful dictionary between the scattering data and observables is established. Implementing methods from scattering theory we prove that this attractive potential leads to a suppression of the quadrupole moment for CMB and B-mode angular power spectra. The scale of the potential is determined by the Hubble parameter during slow roll. Within the effective field theory of inflation at the grand unification (GUT) energy scale we find that if inflation lasts a total number of e-folds Ntot˜59, there is a 10% 20% suppression of the CMB quadrupole and about 2% 4% suppression of the tensor quadrupole. The suppression of higher multipoles is smaller, falling off as 1/l2. The suppression is much smaller for Ntot>59, therefore if the observable suppression originates in the fast roll stage, there is the upper bound Ntot˜59.
CMB dipole asymmetry from a fast roll phase
Mazumdar, Anupam; Wang, Lingfei
2013-10-01
The observed CMB (cosmic microwave background) dipole asymmetry cannot be explained by a single field model of inflation - it inevitably requires more than one field where one of the fields is responsible for amplifying the super-Hubble fluctuations beyond the pivot scale. Furthermore the current constraints on f{sub NL} and τ{sub NL} require that such an amplification cannot produce large non-Gaussianity. In this paper we propose a model to explain this dipole asymmetry from a spectator field, which is responsible for generating all the curvature perturbations, but has a temporary fast roll phase before the Hubble exit of the pivot scale. The current data prefers spectator scenario because it leaves no isocurvature perturbations. The spectator model will also satisfy the well-known constraints arising from quasars, and the quadrupole and octupole of the CMB.
Inflation in the early universe.
NASA Astrophysics Data System (ADS)
Carmeli, M.
1998-04-01
In this talk it will be assumed that gravitation is negligible. Under this assumption, the receding velocities of galaxies and the distances between them in the Hubble expansion are united into a four-dimensional pseudo-Euclidean manifold, similarly to space and time in ordinary special relativity. The Hubble law is assumed and is written in an invariant way that enables one to derive a four-dimensional transformation which is similar to the Lorentz transformation. The parameter in the new transformation is the ratio between the cosmic time to the Hubble time. Accordingly, the new transformation relates physical quantities at different cosmic times in the limit of weak or negligible gravitation. The transformation is then applied to the problem of the expansion of the Universe at the very early stage when gravity was negligible and thus the transformation is applicable. The author calculates the ratio of the volumes of the Universe at two different times T1 and T2 after the big bang. The result conforms with the standard inflationary universe theory, but now it is obtained without assuming that the Universe is propelled by antigravity.
Inflation in the Early Universe
NASA Astrophysics Data System (ADS)
Carmeli, Moshe
In this talk it will be assumed that gravitation is negligible. Under this assumption, the receding velocities of galaxies and the distances between them in the Hubble expansion are united into a four-dimensional pseudo-Euclidean manifold, similarly to space and time in ordinary special relativity. The Hubble law is assumed and is written in an invariant way that enables one to derive a four-dimensional transformation which is similar to the Lorentz transformation. The parameter in the new transformation is the ratio between the cosmic time to the Hubble time (in which the cosmic time is measured backward with respect to the present time). Accordingly, the new transformation relates physical quantities at different cosmic times in the limit of weak or negligible gravitation. The transformation is then applied to the problem of the expansion of the Universe at the very early stage when gravity was negligible and thus the transformation is applicable. We calculate the ratio of the volumes of the Universe at two different times T1 and T2 after the Big Bang. Under the assumptions that T2 - T1 ≈ 10-32
Guth, A H
1993-01-01
A short review of inflation is given, starting with a description of the underlying mechanism and the scenario of events. Four variations--old inflation, new inflation, chaotic inflation, and extended inflation--are discussed. It is claimed that the inflationary model provides a plausible explanation for (i) the large number of particles in the universe, (ii) the Hubble expansion, (iii) the large-scale uniformity of the universe, (iv) the nearness of the universe to a critical density, (v) the absence of magnetic monopoles, and (vi) the scale-invariant spectrum of microwave background fluctuations observed by COBE (Cosmic Background Explorer). Finally, it is argued that the plausibility of inflation is enhanced by the fact that inflation is eternal. Images Fig. 2 PMID:11607402
The Early Universe: Searching for Evidence of Cosmic Inflation
NASA Technical Reports Server (NTRS)
Chuss, David T.
2012-01-01
In the past two decades, our understanding of the evolution and fate of the universe has increased dramatically. This "Age of Precision Cosmology" has been ushered in by measurements that have both elucidated the details of the Big Bang cosmology and set the direction for future lines of inquiry. Our universe appears to consist of 5% baryonic matter; 23% of the universe's energy content is dark matter which is responsible for the observed structure in the universe; and 72% of the energy density is so-called "dark energy" that is currently accelerating the expansion of the universe. In addition, our universe has been measured to be geometrically flat to 1 %. These observations and related details of the Big Bang paradigm have hinted that the universe underwent an epoch of accelerated expansion known as "inflation" early in its history. In this talk, I will review the highlights of modern cosmology, focusing on the contributions made by measurements of the cosmic microwave background, the faint afterglow of the Big Bang. I will also describe new instruments designed to measure the polarization of the cosmic microwave background in order to search for evidence of cosmic inflation.
Impaired swim bladder inflation in early-life stage fathead ...
The present study investigated whether inhibition of deiodinase, the enzyme which converts thyroxine (T4) to the more biologically-active form, 3,5,3'-triiodothyronine (T3), would impact inflation of the posterior and/or anterior chamber of the swim bladder, processes previously demonstrated to be thyroid-hormone regulated. Two experiments were conducted using a model deiodinase inhibitor, iopanoic acid (IOP). In the first study, fathead minnow (Pimephales promelas) embryos were exposed to 0.6, 1.9, or 6.0 mg IOP/L or control water in a flow-through system until reaching 6 days post-fertilization (dpf) at which time posterior swim bladder inflation was assessed. To examine effects on anterior swim bladder inflation, a second study was conducted with 6 dpf larvae exposed to the same IOP concentrations until reaching 21 dpf. Fish from both studies were sampled for T4/T3 measurements, gene transcription analyses, and thyroid histopathology. In the embryo study, incidence and length of inflated posterior swim bladders were significantly reduced in the 6.0 mg/L treatment at 6 dpf. Incidence of inflation and length of anterior swim bladder in larval fish were significantly reduced in all IOP treatments at 14 dpf, but inflation recovered by 18 dpf. Throughout the larval study, whole body T4 concentrations were significantly increased and T3 concentrations were significantly decreased in all IOP treatments. Consistent with hypothesized compensatory responses, sig
NASA Astrophysics Data System (ADS)
Linde, A.; Murdin, P.
2000-11-01
According to inflationary theory, there was a stage of exponentially rapid expansion of the early universe. The existence of this stage resolves many long-standing problems of the BIG BANG THEORY and changes our understanding of the origin of the universe and of its global structure....
Impaired swim bladder inflation in early-life stage fathead ...
The thyroid axis plays a critical role in teleost fish development. The present study investigated whether inhibition of deiodinase, the enzyme which converts thyroxine (T4), to the more biologically-active form, 3,5,3'-triiodothyronine (T3), would impact inflation of the posterior and/or anterior swim bladder (SB), processes which we previously demonstrated to be thyroid-hormone regulated. Two experiments were conducted using iopanoic acid (IOP), a pharmaceutical used to treat hyperthyroidism, as a model deiodinase inhibitor. In the first study, fathead minnow (Pimephales promelas) embryos (~1 day post-fertilization [dpf]) were exposed in a flow-through system to three concentrations of IOP (0.6, 1.9, 6.0 mg/L) or control water and sampled at 4 and 6 dpf. Whole body T4 and T3 concentrations were measured using LC-MS/MS. Abundance of deiodinase 1-3 (dio1-3), thyroid-stimulating hormone (tsh), and thyroperoxidase (tpo) transcripts was examined using quantitative polymerase-chain reaction. Posterior SB inflation was assessed at 6 dpf. To examine effects on anterior SB inflation, a second study was conducted in which 6 dpf larvae, whose posterior SB had already inflated, were exposed to the same IOP concentrations. Fish were sampled at 10, 14, 18, and 21 dpf for T4/T3 measurements, gene transcription analyses, and thyroid histopathology. In the embryo study, incidence and length of inflated posterior SBs were significantly reduced in the 6.0 mg/L treatment at 6 dp
Early history of inflatable penile prosthesis surgery: a view from someone who was there
Mobley, David F
2015-01-01
The publication of the use of an inflatable penile prosthesis (IPP) in 1973 by Dr. FB Scott. changed the world of treatment options for erectile dysfunction (ED). Much has been written since then about techniques, improvements, management of difficult cases, complications and their management, and mechanical and device changes over time. Few reports, if any, are available in the medical literature regarding the early development, surgical techniques, and controversies surrounding its introduction to the world's urological community. This article is, for the most part, the observations of one who was “there” in the early and mid-1970's and was a witness to the history of this remarkable marvel of creativity, engineering, design, and to the personalities involved. PMID:25432494
Early history of inflatable penile prosthesis surgery: a view from someone who was there.
Mobley, David F
2015-01-01
The publication of the use of an inflatable penile prosthesis (IPP) in 1973 by Dr. FB Scott. changed the world of treatment options for erectile dysfunction (ED). Much has been written since then about techniques, improvements, management of difficult cases, complications and their management, and mechanical and device changes over time. Few reports, if any, are available in the medical literature regarding the early development, surgical techniques, and controversies surrounding its introduction to the world's urological community. This article is, for the most part, the observations of one who was "there" in the early and mid-1970's and was a witness to the history of this remarkable marvel of creativity, engineering, design, and to the personalities involved.
NASA Astrophysics Data System (ADS)
Hassan, Syed Moeez; Husain, Viqar; Seahra, Sanjeev S.
2015-03-01
We consider the semiclassical dynamics of a free massive scalar field in a homogeneous and isotropic cosmological spacetime. The scalar field is quantized using the polymer quantization method assuming that it is described by a Gaussian coherent state. For quadratic potentials, the semiclassical equations of motion yield a universe that has an early "polymer inflation" phase which is generic and almost exactly de Sitter, followed by an epoch of slow-roll inflation. We compute polymer corrections to the slow-roll formalism, and discuss the probability of inflation in this model using a physical Hamiltonian arising from time gauge fixing. We also show how in this model, it is possible to obtain a significant amount of slow-roll inflation from sub-Planckian initial data, hence circumventing some of the criticisms of standard scenarios. These results show the extent to which a quantum gravity motivated quantization method affects early universe dynamics.
Large slow roll parameters in single field inflation
Cook, Jessica L.; Krauss, Lawrence M. E-mail: krauss@asu.edu
2016-03-01
We initially consider two simple situations where inflationary slow roll parameters are large and modes no longer freeze out shortly after exiting the horizon, treating both cases analytically. By modes, we refer to the comoving curvature perturbation R. We then consider applications to transient phases where the slow roll parameters can become large, especially in the context of the common 'fast-roll' inflation frequently used as a mechanism to explain the anomalously low scalar power at low l in the CMB. These transient cases we treat numerically. We find when ε, the first slow roll parameter, and only ε is large, modes decay outside the horizon, and when δ, the second slow roll parameter, is large, modes grow outside the horizon. When multiple slow roll parameters are large the behavior in general is more complicated, but we nevertheless show in the 'fast-roll' inflation case, modes grow outside the horizon.
Early inflation to late-time acceleration in f(G) model
NASA Astrophysics Data System (ADS)
Dutta, Malay Krishna; Sarkar, Kaushik; Modak, B.
2016-09-01
We present some solutions in Friedmann-Lemaître-Robertson-Walker (FLRW) spacetime in the modified theory of gravity with a general Gauss-Bonnet (GB) term f(G) and R2 including an ideal fluid. We present evolution of the universe introducing an ansatz without a prior choice of f(G) in one approach, while in other class of model, the solutions are obtained assuming few simple forms of f(G). Some of the solutions show early inflationary expansion, further in one solution the fluctuation of the deceleration parameter q is evident at the end of inflation. In all cases, late-time transition to accelerating universe at redshift z ˜ 0.7 is realizable.
A New Look at Inflation: Economic Policy in the Early 1970s.
ERIC Educational Resources Information Center
Cagan, Phillip; And Others
The volume, a sequel to "Economic Policy and Inflation in the Sixties" presents the diverse opinions of distinguished scholars on developments in the American economy since the institution of direct wage and price controls in August 1971. Gottfried Haberler considers the international aspects of recent United States inflation. William…
Barenboim, Gabriela; Lykken, Joseph D.; /Fermilab
2005-04-01
We present a new approach to quintessential inflation, in which both dark energy and inflation are explained by the evolution of a single scalar field. We start from a simple scalar potential with both oscillatory and exponential behavior.We employ the conventional reheating mechanism of new inflation, in which the scalar decays to light fermions with a decay width that is proportional to the scalar mass. Because our scalar mass is proportional to the Hubble rate, this gives adequate reheating at early times while shutting off at late times to preserve quintessence and satisfy nucleosynthesis constraints. We discuss a simple model which solves the horizon, flatness, and ''why now'' problems. Without any additional tuning of parameters, this model satisfies all constraints from CMB, large scale structure, and nucleosynthesis. The predictions for the inflationary spectral indices are n{sub S} = n{sub T} = 1. In this model we are currently beginning the third cosmic epoch of accelerated expansion.
Dong, Ruifeng; Kinney, William H.; Stojkovic, Dejan E-mail: whkinney@buffalo.edu
2014-01-01
We define a new inflationary scenario in which inflation starts naturally after the Big Bang when the energy density drops below some critical value. As a model, we use recently proposed symmetron field whose effective potential depends on the energy density of the environment. At high densities, right after the Big Bang, the potential for the symmetron is trivial, and the field sits in equilibrium at the bottom of the potential. When the density drops below some critical value, the potential changes its shape into a symmetry breaking potential, and the field starts rolling down. This scenario does not require any special initial conditions for inflation to start. We also construct a concrete model with two fields, i.e. with symmetron as an inflaton and an additional scalar field which describes the matter content in the early universe. For the simplest coupling, the amplitude and shape of the power spectrum are the same as in the single field slow-roll inflation.
Hybrid inflation in the complex plane
NASA Astrophysics Data System (ADS)
Buchmüller, W.; Domcke, V.; Kamada, K.; Schmitz, K.
2014-07-01
Supersymmetric hybrid inflation is an exquisite framework to connect inflationary cosmology to particle physics at the scale of grand unification. Ending in a phase transition associated with spontaneous symmetry breaking, it can naturally explain the generation of entropy, matter and dark matter. Coupling F-term hybrid inflation to soft supersymmetry breaking distorts the rotational invariance in the complex inflaton plane — an important fact, which has been neglected in all previous studies. Based on the δ N formalism, we analyze the cosmological perturbations for the first time in the full two-field model, also taking into account the fast-roll dynamics at and after the end of inflation. As a consequence of the two-field nature of hybrid inflation, the predictions for the primordial fluctuations depend not only on the parameters of the Lagrangian, but are eventually fixed by the choice of the inflationary trajectory. Recognizing hybrid inflation as a two-field model resolves two shortcomings often times attributed to it: the fine-tuning problem of the initial conditions is greatly relaxed and a spectral index in accordance with the PLANCK data can be achieved in a large part of the parameter space without the aid of supergravity corrections. Our analysis can be easily generalized to other (including large-field) scenarios of inflation in which soft supersymmetry breaking transforms an initially single-field model into a multi-field model.
Frieman, J.A.
1991-02-01
A pseduo-Nambu-Goldstone boson, with a potential of the form V({phi}) = {Lambda}{sup 4}(1 {plus minus} cos({phi}/f)), can naturally give rise to an epoch of inflation in the early universe. Successful inflation can be achieved if f {approximately} m{sub pl} and {Lambda} {approximately} m{sub GUT}. Such mass scales arise in particle physics models with a gauge group that becomes strongly interacting a the GUT scale, e.g., as is expected to happen in the hidden sector of superstring theories. The density fluctuation spectrum is a non-scale-invariant power law, with extra power on large scales. 12 refs., 3 figs.
NASA Astrophysics Data System (ADS)
Chavanis, Pierre-Henri
2013-07-01
We construct a simple model of universe which "unifies" vacuum energy and radiation on the one hand, and matter and dark energy on the other hand in the spirit of a generalized Chaplygin gas model. Specifically, the phases of early inflation and late accelerated expansion are described by a generalized equation of state p/c2 = αρ+kρ1+1/n having a linear component p = αρc2 and a polytropic component p = kρ1+1/nc2. For α = 1/3, n = 1 and k = -4/(3ρP), where ρP = 5.161099 g/m3 is the Planck density, this equation of state describes the transition between the vacuum energy era and the radiation era. For t >= 0, the universe undergoes an inflationary expansion that brings it from the Planck size lP = 1.6210-35 m to a size a1 = 2.6110-6 m on a timescale of about 23.3 Planck times tP = 5.3910-44 s (early inflation). When t > t1 = 23.3tP, the universe decelerates and enters in the radiation era. We interpret the transition from the vacuum energy era to the radiation era as a second order phase transition where the Planck constant ℏ plays the role of finite size effects (the standard Big Bang theory is recovered for ℏ = 0). For α = 0, n = -1 and k = -ρΛ, where ρΛ = 7.0210-24 g/m3 is the cosmological density, the equation of state p/c2 = αρ+kρ1+1/n describes the transition from a decelerating universe dominated by pressureless matter (baryonic and dark matter) to an accelerating universe dominated by dark energy (late inflation). This transition takes place at a size a2 = 0.204lΛ. corresponding to a time t2 = 0.203tΛ where lΛ = 4.38 1026 m is the cosmological length and tΛ = 1.46 1018 s the cosmological time. The present universe turns out to be just at the transition between these two periods (t0 ~ t2). Our model gives the same results as the standard ΛCDM model for t >> tP and completes it by incorporating a phase of early inflation for t < 23.3tP in a very natural manner. Furthermore, it reveals a nice "symmetry" between the early and the late
Chavanis, Pierre-Henri
2013-07-23
We construct a simple model of universe which 'unifies' vacuum energy and radiation on the one hand, and matter and dark energy on the other hand in the spirit of a generalized Chaplygin gas model. Specifically, the phases of early inflation and late accelerated expansion are described by a generalized equation of state p/c{sup 2} = αρ+kρ{sup 1+1/n} having a linear component p = αρc{sup 2} and a polytropic component p = kρ{sup 1+1/n}c{sup 2}. For α= 1/3, n= 1 and k=−4/(3ρ{sub P}), where ρ{sub P}= 5.1610{sup 99} g/m{sup 3} is the Planck density, this equation of state describes the transition between the vacuum energy era and the radiation era. For t≥ 0, the universe undergoes an inflationary expansion that brings it from the Planck size l{sub P}= 1.6210{sup −35} m to a size a{sub 1}= 2.6110{sup −6} m on a timescale of about 23.3 Planck times t{sub P}= 5.3910{sup −44} s (early inflation). When t > t{sub 1}= 23.3t{sub P}, the universe decelerates and enters in the radiation era. We interpret the transition from the vacuum energy era to the radiation era as a second order phase transition where the Planck constant ℏ plays the role of finite size effects (the standard Big Bang theory is recovered for ℏ= 0). For α= 0, n=−1 and k=−ρ{sub Λ}, where ρ{sub Λ}= 7.0210{sup −24} g/m{sup 3} is the cosmological density, the equation of state p/c{sup 2} = αρ+kρ{sup 1+1/n} describes the transition from a decelerating universe dominated by pressureless matter (baryonic and dark matter) to an accelerating universe dominated by dark energy (late inflation). This transition takes place at a size a{sub 2}= 0.204l{sub Λ}. corresponding to a time t{sub 2}= 0.203t{sub Λ} where l{sub Λ}= 4.38 10{sup 26} m is the cosmological length and t{sub Λ}= 1.46 10{sup 18} s the cosmological time. The present universe turns out to be just at the transition between these two periods (t{sub 0}∼t{sub 2}). Our model gives the same results as the standard
F-Term Hybrid Inflation Followed by Modular Inflation
Pallis, C.
2009-05-01
We consider the well motivated model of the (standard)supersymmetric(SUSY)F-term hybrid inflation(FHI) which can be realized close to the grand unification(GUT) scale. The predicted scalar spectral index n{sub s} cannot be smaller than 0.98 and can exceed unity including corrections from minimal supergravity(SUGRA), if the number of e-foldings corresponding to the pivot scale k{sub *} = 0.002/Mpc is around 50. These results are marginally consistent with the fitting of the five-year Wilkinson microwave anisotropy probe(WMAP5) data by the standard power-law cosmological model with cold dark matter and a cosmological constant, {lambda}CDM. However, n{sub s} can be reduced by restricting the number of e-foldings that k{sub *} suffered during FHI. The additional e-foldings required for solving the horizon and flatness problems can be generated by a subsequent stage of fast-roll [slow-roll]modular inflation(MI) realized by a string modulus which does [does not] acquire effective mass (m{sub s|eff}) before the onset of MI.
Lincoln, Don
2016-07-12
In 1964, scientists discovered a faint radio hiss coming from the heavens and realized that the hiss wasnât just noise. It was a message from eons ago; specifically the remnants of the primordial fireball, cooled to about 3 degrees above absolute zero. Subsequent research revealed that the radio hiss was the same in every direction. The temperature of the early universe was uniform to at better than a part in a hundred thousand. And this was weird. According to the prevailing theory, the two sides of the universe have never been in contact. So how could two places that had never been in contact be so similar? One possible explanation was proposed in 1979. Called inflation, the theory required that early in the history of the universe, the universe expanded faster than the speed of light. Confused? Watch this video as Fermilabâs Dr. Don Lincoln makes sense of this mind-bending idea.
Lincoln, Don
2015-11-21
In 1964, scientists discovered a faint radio hiss coming from the heavens and realized that the hiss wasn’t just noise. It was a message from eons ago; specifically the remnants of the primordial fireball, cooled to about 3 degrees above absolute zero. Subsequent research revealed that the radio hiss was the same in every direction. The temperature of the early universe was uniform to at better than a part in a hundred thousand. And this was weird. According to the prevailing theory, the two sides of the universe have never been in contact. So how could two places that had never been in contact be so similar? One possible explanation was proposed in 1979. Called inflation, the theory required that early in the history of the universe, the universe expanded faster than the speed of light. Confused? Watch this video as Fermilab’s Dr. Don Lincoln makes sense of this mind-bending idea.
NASA Technical Reports Server (NTRS)
Berkin, Andrew L.; Maeda, Kei-Ichi; Yokoyama, Junichi
1990-01-01
The cosmology resulting from two coupled scalar fields was studied, one which is either a new inflation or chaotic type inflation, and the other which has an exponentially decaying potential. Such a potential may appear in the conformally transformed frame of generalized Einstein theories like the Jordan-Brans-Dicke theory. The constraints necessary for successful inflation are examined. Conventional GUT models such as SU(5) were found to be compatible with new inflation, while restrictions on the self-coupling constant are significantly loosened for chaotic inflation.
Power suppression at large scales in string inflation
Cicoli, Michele; Downes, Sean; Dutta, Bhaskar E-mail: sddownes@physics.tamu.edu
2013-12-01
We study a possible origin of the anomalous suppression of the power spectrum at large angular scales in the cosmic microwave background within the framework of explicit string inflationary models where inflation is driven by a closed string modulus parameterizing the size of the extra dimensions. In this class of models the apparent power loss at large scales is caused by the background dynamics which involves a sharp transition from a fast-roll power law phase to a period of Starobinsky-like slow-roll inflation. An interesting feature of this class of string inflationary models is that the number of e-foldings of inflation is inversely proportional to the string coupling to a positive power. Therefore once the string coupling is tuned to small values in order to trust string perturbation theory, enough e-foldings of inflation are automatically obtained without the need of extra tuning. Moreover, in the less tuned cases the sharp transition responsible for the power loss takes place just before the last 50-60 e-foldings of inflation. We illustrate these general claims in the case of Fibre Inflation where we study the strength of this transition in terms of the attractor dynamics, finding that it induces a pivot from a blue to a redshifted power spectrum which can explain the apparent large scale power loss. We compute the effects of this pivot for example cases and demonstrate how magnitude and duration of this effect depend on model parameters.
NASA Astrophysics Data System (ADS)
Antusch, S.; King, S. F.; Malinský, M.; Velasco-Sevilla, L.; Zavala, I.
2008-08-01
We propose an entirely new class of particle physics models of inflation based on the phase transition associated with the spontaneous breaking of family symmetry responsible for the generation of the effective quark and lepton Yukawa couplings. We show that the Higgs fields responsible for the breaking of family symmetry, called flavons, are natural candidates for the inflaton field in new inflation, or the waterfall fields in hybrid inflation. This opens up a rich vein of possibilities for inflation, all linked to the physics of flavour, with interesting cosmological and phenomenological implications. Out of these, we discuss two examples which realise flavon inflation: a model of new inflation based on the discrete non-Abelian family symmetry group A or Δ, and a model of hybrid inflation embedded in an existing flavour model with a continuous SU(3) family symmetry. With the inflation scale and family symmetry breaking scale below the Grand Unification Theory (GUT) scale, these classes of models are free of the monopole (and similar) problems which are often associated with the GUT phase transition.
NASA Astrophysics Data System (ADS)
Murphy, Philip Joseph
1987-09-01
The Theory of Inflation, namely, that at some point the entropy content of the universe was greatly increased, has much promise. It may solve the puzzles of homogeneity and the creation of structure. However, no particle physics model has yet been found that can successfully drive inflation. The difficulty in satisfying the constraint that the isotropy of the microwave background places on the effective potential of prospective models is immense. In this work we have codified the requirements of such models in a most general form. We have carefully calculated the amounts of inflation the various problems of the Standard Model need for their solution. We have derived a completely model independent upper bound on the inflationary Hubble parameter. We have developed a general notation with which to probe the possibilities of Multiple Inflation. We have shown that only in very unlikely circumstances will any evidence of an earlier inflation, survive the de Sitter period of its successor. In particular, it is demonstrated that it is most unlikely that two bouts of inflation will yield high amplitudes of density perturbations on small scales and low amplitudes on large. We conclude that, while multiple inflation will be of great theoretical interest, it is unlikely to have any observational impact.
Burrage, Clare; Rham, Claudia de; Seery, David; Tolley, Andrew J. E-mail: Claudia.deRham@unige.ch E-mail: andrew.j.tolley@case.edu
2011-01-01
Galileon inflation is a radiatively stable higher derivative model of inflation. The model is determined by a finite number of relevant operators which are protected by a covariant generalization of the Galileon shift symmetry.We show that the nongaussianity of the primordial density perturbation generated during an epoch of Galileon inflation is a particularly powerful observational probe of these models and that, when the speed of sound is small, f{sub NL} can be larger than the usual result f{sub NL}∝c{sub s}{sup −2}.
Finite Inflation, Holography, and Dark Matter Annihilation
NASA Astrophysics Data System (ADS)
Scacco, Andrew Joseph
This thesis covers work on theoretical cosmology relating to inflation, de Sitter space, dark matter annihilation, and holography. A unifying feature of all these topics is that all of them occur in de Sitter space or focus on epochs of the Universe when the spacetime was close to de Sitter and that all of them have some connection to holography. Chapter 1 provides a pedagogical introduction to the fundamentals of cosmology, inflation, de Sitter space, dark matter annihilation and entanglement entropy. Chapter 2 covers the impact on the causal entropic principle of dark matter annihilation that we find to have the greatest relevance at late times in the future when the dark energy has driven the universe to be asymptotically de Sitter. In this chapter we estimate holographically preferred dark matter properties for a range of assumptions. Chapter 3 covers holographic bounds in models of finite inflation, specifically the Banks-Fischler bound and de Sitter equilibrium. The assumptions in each of these models are explored in detail and some interesting new connections are presented. Chapter 4 tests models of inflation with a fast-roll start that happen to satisfy the holographic bounds in Chapter 3 against cosmic microwave background data from Planck. We find a slight preference for a feature at the scale predicted by the Banks-Fischler bound though this preference is not found to be statistically significant. Chapter 5 contains a numerical computation of the holographic mutual information for an annular configuration of regions on a conformal field theory in de Sitter space using the AdS/CFT correspondence. This computation shows that the de Sitter space CFT entanglement entropy matches what would be expected from a Minkowski CFT and shows that the HRT conjecture works for this case.
Priddy, Tommy G.
1988-01-01
An inflatable wing is formed from a pair of tapered, conical inflatable tubes in bonded tangential contact with each other. The tubes are further connected together by means of top and bottom reinforcement boards having corresponding longitudinal edges lying in the same central diametral plane passing through the associated tube. The reinforcement boards are made of a stiff reinforcement material, such as Kevlar, collapsible in a direction parallel to the spanwise wing axis upon deflation of the tubes. The stiff reinforcement material cooperates with the inflated tubes to impart structural I-beam characteristics to the composite structure for transferring inflation pressure-induced tensile stress from the tubes to the reinforcement boards. A plurality of rigid hoops shaped to provide airfoil definition are spaced from each other along the spanwise axis and are connected to the top and bottom reinforcement boards. Tension lines are employed for stabilizing the hoops along the trailing and leading edges thereof.
The thyroid axis plays a critical role in teleost fish development. The present study investigated whether inhibition of deiodinase, the enzyme which converts thyroxine (T4), to the more biologically-active form, 3,5,3'-triiodothyronine (T3), would impact inflation of the posteri...
The present study investigated whether inhibition of deiodinase, the enzyme which converts thyroxine (T4) to the more biologically-active form, 3,5,3'-triiodothyronine (T3), would impact inflation of the posterior and/or anterior chamber of the swim bladder, processes previously ...
Davoudiasl, Hooman; Hooper, Dan; McDermott, Samuel D
2016-01-22
We describe a general scenario, dubbed "inflatable dark matter," in which the density of dark matter particles can be reduced through a short period of late-time inflation in the early Universe. The overproduction of dark matter that is predicted within many, otherwise, well-motivated models of new physics can be elegantly remedied within this context. Thermal relics that would, otherwise, be disfavored can easily be accommodated within this class of scenarios, including dark matter candidates that are very heavy or very light. Furthermore, the nonthermal abundance of grand unified theory or Planck scale axions can be brought to acceptable levels without invoking anthropic tuning of initial conditions. A period of late-time inflation could have occurred over a wide range of scales from ∼MeV to the weak scale or above, and could have been triggered by physics within a hidden sector, with small but not necessarily negligible couplings to the standard model.
NASA Astrophysics Data System (ADS)
Davoudiasl, Hooman; Hooper, Dan; McDermott, Samuel D.
2016-01-01
We describe a general scenario, dubbed "inflatable dark matter," in which the density of dark matter particles can be reduced through a short period of late-time inflation in the early Universe. The overproduction of dark matter that is predicted within many, otherwise, well-motivated models of new physics can be elegantly remedied within this context. Thermal relics that would, otherwise, be disfavored can easily be accommodated within this class of scenarios, including dark matter candidates that are very heavy or very light. Furthermore, the nonthermal abundance of grand unified theory or Planck scale axions can be brought to acceptable levels without invoking anthropic tuning of initial conditions. A period of late-time inflation could have occurred over a wide range of scales from ˜MeV to the weak scale or above, and could have been triggered by physics within a hidden sector, with small but not necessarily negligible couplings to the standard model.
NASA Astrophysics Data System (ADS)
García-Bellido, Juan; Garriga, Jaume; Montes, Xavier
1998-04-01
We show that a large class of two-field models of single-bubble open inflation does not lead to infinite open universes, as was previously thought, but to an ensemble of very large but finite inflating ``islands.'' The reason is that the quantum tunneling responsible for the nucleation of the bubble does not occur simultaneously along both field directions and equal-time hypersurfaces in the open universe are not synchronized with equal-density or fixed-field hypersurfaces. The most probable tunneling trajectory corresponds to a zero value of the inflaton field; large values, necessary for the second period of inflation inside the bubble, only arise as localized fluctuations. The interior of each nucleated bubble will contain an infinite number of such inflating regions of comoving size of order γ-1, where γ is the supercurvature eigenvalue, which depends on the parameters of the model. Each one of these islands will be a quasi-open universe. Since the volume of the hyperboloid is infinite, inflating islands with all possible values of the field at their center will be realized inside of a single bubble. We may happen to live in one of those patches of comoving size d<~γ-1, where the universe appears to be open. In particular, we consider the ``supernatural'' model proposed by Linde and Mezhlumian. There, an approximate U(1) symmetry is broken by a tunneling field in a first order phase transition, and slow-roll inflation inside the nucleated bubble is driven by the pseudo Goldstone field. We find that the excitations of the pseudo Goldstone field produced by the nucleation and subsequent expansion of the bubble place severe constraints on this model. We also discuss the coupled and uncoupled two-field models.
Kim, Yoonbai; Park, Seong Chan
2011-03-15
We propose a natural scenario for the cosmological inflation with the nonminimal coupling term invoking compact hyperbolic extra dimensions. Thanks to the unique mathematical properties of compact hyperbolic space, the large volume of extra dimensions, which provides a natural understanding of the proper size of couplings, does not necessarily accompany with the low Kaluza-Klein scale so that the model allows a single field inflation with a scale around 10{sup 13} GeV. The model fulfills all the observed data and predicts a sizable gravitational perturbation, r{approx_equal}3x10{sup -3}.
Green, Daniel; Horn, Bart; Senatore, Leonardo; Silverstein, Eva; /SLAC /Stanford U., Phys. Dept.
2009-06-19
We analyze a distinctive mechanism for inflation in which particle production slows down a scalar field on a steep potential, and show how it descends from angular moduli in string compactifications. The analysis of density perturbations - taking into account the integrated effect of the produced particles and their quantum fluctuations - requires somewhat new techniques that we develop. We then determine the conditions for this effect to produce sixty e-foldings of inflation with the correct amplitude of density perturbations at the Gaussian level, and show that these requirements can be straightforwardly satisfied. Finally, we estimate the amplitude of the non-Gaussianity in the power spectrum and find a significant equilateral contribution.
NASA Astrophysics Data System (ADS)
Boyanovsky, D.; Destri, C.; de Vega, H. J.; Sanchez, N. G.
effective theory of inflation clearly prefer new inflation. Study of higher degree inflaton potentials shows that terms of degree higher than 4 do not affect the fit in a significant way. In addition, a horizon exit happens for \\varphi/[√ {N}M Pl] ˜ 0.9, making higher order terms in the potential w negligible. We summarize the physical effects of generic initial conditions (different from Bunch-Davies) on the scalar and tensor perturbations during slow roll and introduce the transfer function D(k), which encodes the observable initial condition effects on the power spectra. These effects are more prominent in the low CMB multipoles: a change in the initial conditions during slow roll can account for the observed CMB quadrupole suppression. Slow-roll inflation is generically preceded by a short, fast-roll stage. Bunch-Davies initial conditions are the natural initial conditions for the fast-roll perturbations. During fast roll, the potential in the wave equations of curvature and tensor perturbations is purely attractive and leads to a suppression of the curvature and tensor CMB quadrupoles. An MCMC analysis of the WMAP+SDSS data including fast roll shows that the quadrupole mode exits the horizon about 0.2 e-fold before fast roll ends and its amplitude gets suppressed. In addition, fast roll fixes the initial inflation redshift to be zinit = 0.9 × 1056 and the total number of e-folds of inflation to be Ntot ≃ 64. Fast roll fits the TT, the TE and the EE modes well, reproducing the quadrupole suppression. A thorough study of the quantum loop corrections reveals that they are very small and are controlled by powers of (H/MPl)2 10-9, a conclusion that validates the reliability of the effective theory of inflation. The present review shows how powerful the Ginsburg-Landau effective theory of inflation is in predicting observables that are being or will soon be contrasted with observations.
Natural inflation and quantum gravity.
de la Fuente, Anton; Saraswat, Prashant; Sundrum, Raman
2015-04-17
Cosmic inflation provides an attractive framework for understanding the early Universe and the cosmic microwave background. It can readily involve energies close to the scale at which quantum gravity effects become important. General considerations of black hole quantum mechanics suggest nontrivial constraints on any effective field theory model of inflation that emerges as a low-energy limit of quantum gravity, in particular, the constraint of the weak gravity conjecture. We show that higher-dimensional gauge and gravitational dynamics can elegantly satisfy these constraints and lead to a viable, theoretically controlled and predictive class of natural inflation models.
Green, Dan
2014-03-01
The last few years have yielded remarkable discoveries in physics. In particle physics it appears that a fundamental scalar field exists. The Higgs boson is measured to have a mass of about 126 GeV and to have spin zero and positive parity. The Higgs field is the first fundamental scalar to be discovered in physics. The Cosmic Microwave Background, CMB, is known to have a uniform temperature to parts per 10^{5}, but has well measured fluctuations, which are thought to evolve gravitationally to provide the seeds of the current structure of the Universe. In addition, the Universe appears to contain, at present, an unknown “dark energy”, which is presently the majority energy density of the Universe, larger than either matter or radiation. This may, indeed, be a fundamental scalar field like the Higgs. “Big Bang” (BB) cosmology is a very successful “standard model” in cosmology. However, it cannot explain the uniformity of the CMB because the CMB consists of many regions not causally connected in the context of the BB model. In addition, the Universe appears to be spatially flat. However, in BB cosmology the present spatial curvature is not stable, so that the initial conditions for BB cosmology would need to be fantastically fine-tuned in order to successfully predict the presently small value of the observed curvature. These issues for BB cosmology have led to the hypothesis of “inflation” which postulates an unknown scalar field, not presumably the Higgs field or the dark energy, which causes an exponential expansion of the Universe at very early times. This attractive hypothesis can account for the problems in BB cosmology of flatness and causal CMB connectivity. In addition, the quantum fluctuations of this postulated field provide a natural explanation of the CMB fluctuations which are the seeds of the structure of galaxies. Researchers are now searching for gravitational waves imprinted on the CMB. These would be a “smoking gun” for
D'Amico, Guido; Gobbetti, Roberto; Kleban, Matthew; Schillo, Marjorie E-mail: rg1509@nyu.edu E-mail: mls604@nyu.edu
2013-03-01
Higher-form flux that extends in all 3+1 dimensions of spacetime is a source of positive vacuum energy that can drive meta-stable eternal inflation. If the flux also threads compact extra dimensions, the spontaneous nucleation of a bubble of brane charged under the flux can trigger a classical cascade that steadily unwinds many units of flux, gradually decreasing the vacuum energy while inflating the bubble, until the cascade ends in the self-annihilation of the brane into radiation. With an initial number of flux quanta Q{sub 0}∼>N, this can result in N efolds of inflationary expansion while producing a scale-invariant spectrum of adiabatic density perturbations with amplitude and tilt consistent with observation. The power spectrum has an oscillatory component that does not decay away during inflation, relatively large tensor power, and interesting non-Gaussianities. Unwinding inflation fits naturally into the string landscape, and our preliminary conclusion is that consistency with observation can be attained without fine-tuning the string parameters. The initial conditions necessary for the unwinding phase are produced automatically by bubble formation, so long as the critical radius of the bubble is smaller than at least one of the compact dimensions threaded by flux.
NASA Technical Reports Server (NTRS)
Chuss, David
2010-01-01
The Cosmic Microwave Background (CMB) has provided a wealth of information about the history and physics of the early Universe. Much progress has been made on uncovering the emerging Standard Model of Cosmology by such experiments as COBE and WMAP, and ESA's Planck Surveyor will likely increase our knowledge even more. Despite the success of this model, mysteries remain. Currently understood physics does not offer a compelling explanation for the homogeneity, flatness, and the origin of structure in the Universe. Cosmic Inflation, a brief epoch of exponential expansion, has been posted to explain these observations. If inflation is a reality, it is expected to produce a background spectrum of gravitational waves that will leave a small polarized imprint on the CMB. Discovery of this signal would give the first direct evidence for inflation and provide a window into physics at scales beyond those accessible to terrestrial particle accelerators. I will briefly review aspects of the Standard Model of Cosmology and discuss our current efforts to design and deploy experiments to measure the polarization of the CMB with the precision required to test inflation.
NASA Astrophysics Data System (ADS)
Kehagias, Alex; Riotto, Antonio
2017-04-01
We investigate the recently proposed clockwork mechanism delivering light degrees of freedom with suppressed interactions and show, with various examples, that it can be efficiently implemented in inflationary scenarios to generate flat inflaton potentials and small density perturbations without fine-tunings. We also study the clockwork graviton in de Sitter and, interestingly, we find that the corresponding clockwork charge is site-dependent. As a consequence, the amount of tensor modes is generically suppressed with respect to the standard cases where the clockwork set-up is not adopted. This point can be made a virtue in resurrecting models of inflation which were supposed to be ruled out because of the excessive amount of tensor modes from inflation.
Creminelli, Paolo; Noreña, Jorge; Peña, Manuel; Simonović, Marko E-mail: jorge.norena@icc.ub.edu E-mail: marko.simonovic@sissa.it
2012-11-01
We study the possibility that the approximate time shift symmetry during inflation is promoted to the full invariance under time reparametrization t → t-tilde (t), or equivalently under field redefinition of the inflaton φ → φ-tilde (φ). The symmetry allows only two operators at leading order in derivatives, so that all n-point functions of scalar perturbations are fixed in terms of the power spectrum normalization and the speed of sound. During inflation the decaying mode only decays as 1/a and this opens up the possibility to violate some of the consistency relations in the squeezed limit, although this violation is suppressed by the (small) breaking of the field reparametrization symmetry. In particular one can get terms in the 3-point function that are only suppressed by 1/k{sub L} in the squeezed limit k{sub L}→0 compared to the local shape.
NASA Astrophysics Data System (ADS)
Croon, Djuna; Sanz, Verónica; Setford, Jack
2015-10-01
Identifying the inflaton with a pseudo-Goldstone boson explains the flatness of its potential. Successful Goldstone Inflation should also be robust against UV corrections, such as from quantum gravity: in the language of the effective field theory this implies that all scales are sub-Planckian. In this paper we present scenarios which realise both requirements by examining the structure of Goldstone potentials arising from Coleman-Weinberg contributions. We focus on single-field models, for which we notice that both bosonic and fermionic contributions are required and that spinorial fermion representations can generate the right potential shape. We then evaluate the constraints on non-Gaussianity from higher-derivative interactions, finding that axiomatic constraints on Goldstone boson scattering prevail over the current CMB measurements. The fit to CMB data can be connected to the UV completions for Goldstone Inflation, finding relations in the spectrum of new resonances. Finally, we show how hybrid inflation can be realised in the same context, where both the inflaton and the waterfall fields share a common origin as Goldstones.
NASA Astrophysics Data System (ADS)
Sebastiani, Lorenzo; Myrzakulov, Ratbay
2015-08-01
In this short review, we revisit inflation in F(R)-gravity. We find several F(R)-models for viable inflation by applying some reconstruction techniques. A special attention is payed in the reproduction of the last Planck satellite data. The possible generalizations of Starobinsky-like inflation are found and discussed. The early-time acceleration is analyzed in a higher derivative quantum gravitational model which mainly reduces to F(R)-gravity.
The Primordial Inflation Explorer
NASA Technical Reports Server (NTRS)
Kogut, Alan J.
2012-01-01
The Primordial Inflation Explorer is an Explorer-class mission to measure the gravity-wave signature of primordial inflation through its distinctive imprint on the linear polarization of the cosmic microwave background. PIXIE uses an innovative optical design to achieve background-limited sensitivity in 400 spectral channels spanning 2.5 decades in frequency from 30 GHz to 6 THz (1 cm to 50 micron wavelength). The principal science goal is the detection and characterization of linear polarization from an inflationary epoch in the early universe, with tensor-to-scalar ratio r < 10(exp -3) at 5 standard deviations. The rich PIXIE data set will also constrain physical processes ranging from Big Bang cosmology to the nature of the first stars to physical conditions within the interstellar medium of the Galaxy. I describe the PIXIE instrument and mission architecture needed to detect the inflationary signature using only 4 semiconductor bolometers.
Code of Federal Regulations, 2010 CFR
2010-10-01
... lifejackets, inflatable buoyant apparatus, and inflated rescue boats. 131.580 Section 131.580 Shipping COAST... Inspections § 131.580 Servicing of inflatable liferafts, inflatable lifejackets, inflatable buoyant apparatus, and inflated rescue boats. (a) An inflatable liferaft or inflatable buoyant apparatus must be...
Code of Federal Regulations, 2011 CFR
2011-10-01
... lifejackets, inflatable buoyant apparatus, and inflated rescue boats. 131.580 Section 131.580 Shipping COAST... Inspections § 131.580 Servicing of inflatable liferafts, inflatable lifejackets, inflatable buoyant apparatus, and inflated rescue boats. (a) An inflatable liferaft or inflatable buoyant apparatus must be...
Davoudiasl, Hooman; Hooper, Dan; McDermott, Samuel D.
2016-01-22
We describe a general scenario, dubbed “Inflatable Dark Matter”, in which the density of dark matter particles can be reduced through a short period of late-time inflation in the early universe. The overproduction of dark matter that is predicted within many otherwise well-motivated models of new physics can be elegantly remedied within this context, without the need to tune underlying parameters or to appeal to anthropic considerations. Thermal relics that would otherwise be disfavored can easily be accommodated within this class of scenarios, including dark matter candidates that are very heavy or very light. Furthermore, the non-thermal abundance of GUT or Planck scale axions can be brought to acceptable levels, without invoking anthropic tuning of initial conditions. Additionally, a period of late-time inflation could have occurred over a wide range of scales from ~ MeV to the weak scale or above, and could have been triggered by physics within a hidden sector, with small but not necessarily negligible couplings to the Standard Model.
Davoudiasl, Hooman; Hooper, Dan; McDermott, Samuel D.
2016-01-22
We describe a general scenario, dubbed “Inflatable Dark Matter”, in which the density of dark matter particles can be reduced through a short period of late-time inflation in the early universe. The overproduction of dark matter that is predicted within many otherwise well-motivated models of new physics can be elegantly remedied within this context, without the need to tune underlying parameters or to appeal to anthropic considerations. Thermal relics that would otherwise be disfavored can easily be accommodated within this class of scenarios, including dark matter candidates that are very heavy or very light. Furthermore, the non-thermal abundance of GUTmore » or Planck scale axions can be brought to acceptable levels, without invoking anthropic tuning of initial conditions. Additionally, a period of late-time inflation could have occurred over a wide range of scales from ~ MeV to the weak scale or above, and could have been triggered by physics within a hidden sector, with small but not necessarily negligible couplings to the Standard Model.« less
Gravitational waves from inflation
NASA Astrophysics Data System (ADS)
Guzzetti, M. C.; Bartolo, N.; Liguori, M.; Matarrese, S.
2016-09-01
The production of a stochastic background of gravitational waves is a fundamental prediction of any cosmological inflationary model. The features of such a signal encode unique information about the physics of the Early Universe and beyond, thus representing an exciting, powerful window on the origin and evolution of the Universe. We review the main mechanisms of gravitational-wave production, ranging from quantum fluctuations of the gravitational field to other mechanisms that can take place during or after inflation. These include e.g. gravitational waves generated as a consequence of extra particle production during inflation, or during the (p)reheating phase. Gravitational waves produced in inflation scenarios based on modified gravity theories and second-order gravitational waves are also considered. For each analyzed case, the expected power spectrum is given. We discuss the discriminating power among different models, associated with the validity/violation of the standard consistency relation between tensor-to-scalar ratio r and tensor spectral index nT. In light of the prospects for (directly/indirectly) detecting primordial gravitational waves, we give the expected present-day gravitational radiation spectral energy-density, highlighting the main characteristics imprinted by the cosmic thermal history, and we outline the signatures left by gravitational waves on the Cosmic Microwave Background and some imprints in the Large-Scale Structure of the Universe. Finally, current bounds and prospects of detection for inflationary gravitational waves are summarized.
NASA Astrophysics Data System (ADS)
Maleknejad, A.; Sheikh-Jabbari, M. M.; Soda, J.
2013-07-01
The isotropy and homogeneity of the cosmic microwave background (CMB) favors “scalar driven” early Universe inflationary models. However, gauge fields and other non-scalar fields are far more common at all energy scales, in particular at high energies seemingly relevant to inflation models. Hence, in this review we consider the role and consequences, theoretical and observational, that gauge fields can have during the inflationary era. Gauge fields may be turned on in the background during inflation, or may become relevant at the level of cosmic perturbations. There have been two main classes of models with gauge fields in the background, models which show violation of the cosmic no-hair theorem and those which lead to isotropic FLRW cosmology, respecting the cosmic no-hair theorem. Models in which gauge fields are only turned on at the cosmic perturbation level, may source primordial magnetic fields. We also review specific observational features of these models on the CMB and/or the primordial cosmic magnetic fields. Our discussions will be mainly focused on the inflation period, with only a brief discussion on the post inflationary (p)reheating era. Large field models: The initial value of the inflaton field is large, generically super-Planckian, and it rolls slowly down toward the potential minimum at smaller φ values. For instance, chaotic inflation is one of the representative models of this class. The typical potential of large-field models has a monomial form as V(φ)=V0φn. A simple analysis using the dynamical equations reveals that for number of e-folds Ne larger than 60, we require super-Planckian initial field values,5φ0>3M. For these models typically ɛ˜η˜Ne-1. Small field models: Inflaton field is initially small and slowly evolves toward the potential minimum at larger φ values. The small field models are characterized by the following potential V(φ)=V0(1-(), which corresponds to a Taylor expansion about the origin, but more realistic
NASA Astrophysics Data System (ADS)
Tackley, P. J.
2004-12-01
Inflatable devices are frequently used in advertising in order to grab the attention of consumers: one sees, for example, 20 foot tall inflatable drink containers, inflatable cell phones, inflatable bubble gum packets, as well as blimps wafting majestically over major sports events. More usefully, inflatable representations of scientifically-interesting items are widely available, including astronauts, space shuttles, dinosaurs and globes and can help to build and inspire the interest of the general public, and in particular children, in such ideas. How can such concepts be adapted to improve poster presentations? Possibility one is to use relevant existing commercially-available inflatables to dress the poster: skeletons, astronauts, globes and so forth. More exciting is to develop custom inflatables that represent three-dimensional renderings of objects that the poster is describing. Examples of individual objects might be an inflatable slab, inflatable avalanche, inflatable plume, or it's larger cousin, the 10 foot high inflatable superplume or 20 foot high inflatable megaplume. More elaborately, inflatables might represent isosurfaces in three-dimensional spherical convection, although other fabrication methods may be more suitable. More simply, inflatable spheres could be imprinted with the planform of convection, geoid, or other spherical fields of geophysical interest. Finally, it should be possible to put an entire poster on an inflatable object, possibly small ones (balloons) to hand out. A major concern, however, is that the presenter may use such techniques to inflate their scientific findings, or to present overblown ideas.
Code of Federal Regulations, 2012 CFR
2012-10-01
... apparatus, inflatable life jackets, and inflated rescue boats. 122.730 Section 122.730 Shipping COAST GUARD..., inflatable life jackets, and inflated rescue boats. (a) An inflatable liferaft or inflatable buoyant... other standard specified by the Commandant. (e) Repair and maintenance of inflated rescue boats must...
Code of Federal Regulations, 2013 CFR
2013-10-01
... apparatus, inflatable life jackets, and inflated rescue boats. 122.730 Section 122.730 Shipping COAST GUARD..., inflatable life jackets, and inflated rescue boats. (a) An inflatable liferaft or inflatable buoyant... other standard specified by the Commandant. (e) Repair and maintenance of inflated rescue boats must...
Code of Federal Regulations, 2014 CFR
2014-10-01
... apparatus, inflatable life jackets, and inflated rescue boats. 122.730 Section 122.730 Shipping COAST GUARD..., inflatable life jackets, and inflated rescue boats. (a) An inflatable liferaft or inflatable buoyant... other standard specified by the Commandant. (e) Repair and maintenance of inflated rescue boats must...
Adshead, Peter; Easther, Richard E-mail: richard.easther@yale.edu
2008-10-15
We analyze the theoretical limits on slow roll reconstruction, an optimal algorithm for recovering the inflaton potential (assuming a single-field slow roll scenario) from observational data. Slow roll reconstruction is based upon the Hamilton-Jacobi formulation of the inflationary dynamics. We show that at low inflationary scales the Hamilton-Jacobi equations simplify considerably. We provide a new classification scheme for inflationary models, based solely on the number of parameters needed to specify the potential, and provide forecasts for the bounds on the slow roll parameters from future data sets. A minimal running of the spectral index, induced solely by the first two slow roll parameters ({epsilon} and {eta}), appears to be effectively undetectable by realistic cosmic microwave background (CMB) experiments. However, since the ability to detect any running increases with the lever arm in comoving wavenumber, we conjecture that high redshift 21 cm data may allow tests of second-order consistency conditions on inflation. Finally, we point out that the second-order corrections to the spectral index are correlated with the inflationary scale, and thus the amplitude of the CMB B mode.
Effects of thermal fluctuations on thermal inflation
Hiramatsu, Takashi; Miyamoto, Yuhei; Yokoyama, Jun'ichi E-mail: miyamoto@resceu.s.u-tokyo.ac.jp
2015-03-01
The mechanism of thermal inflation, a relatively short period of accelerated expansion after primordial inflation, is a desirable ingredient for a certain class of particle physics models if they are not to be in contention with the cosmology of the early Universe. Though thermal inflation is most simply described in terms of a thermal effective potential, a thermal environment also gives rise to thermal fluctuations that must be taken into account. We numerically study the effects of these thermal fluctuations using lattice simulations. We conclude that though they do not ruin the thermal inflation scenario, the phase transition at the end of thermal inflation proceeds through phase mixing and is therefore not accompanied by the formations of bubbles nor appreciable amplitude of gravitational waves.
Effects of thermal fluctuations on thermal inflation
Hiramatsu, Takashi; Miyamoto, Yuhei; Yokoyama, Jun’ichi
2015-03-12
The mechanism of thermal inflation, a relatively short period of accelerated expansion after primordial inflation, is a desirable ingredient for a certain class of particle physics models if they are not to be in contention with the cosmology of the early Universe. Though thermal inflation is most simply described in terms of a thermal effective potential, a thermal environment also gives rise to thermal fluctuations that must be taken into account. We numerically study the effects of these thermal fluctuations using lattice simulations. We conclude that though they do not ruin the thermal inflation scenario, the phase transition at the end of thermal inflation proceeds through phase mixing and is therefore not accompanied by the formations of bubbles nor appreciable amplitude of gravitational waves.
Kolb, E.W. Chicago Univ., IL . Enrico Fermi Inst.)
1990-09-01
In the original proposal, inflation occurred in the process of a strongly first-order phase transition. This model was soon demonstrated to be fatally flawed. Subsequent models for inflation involved phase transitions that were second-order, or perhaps weakly first-order; some even involved no phase transition at all. Recently the possibility of inflation during a strongly first-order phase transition has been revived. In this talk I will discuss some models for first-order inflation, and emphasize unique signatures that result in inflation is realized in a first-order transition. Before discussing first-order inflation, I will briefly review some of the history of inflation to demonstrate how first-order inflation differs from other models. 58 refs., 3 figs.
Cosmological relaxation and high scale inflation
NASA Astrophysics Data System (ADS)
Higaki, Tetsutaro; Takeda, Naoyuki; Yamada, Yusuke
2017-01-01
The relaxion mechanism elegantly solves the Higgs hierarchy problem, but it requires that the early Universe experiences a long inflation phase with a small energy scale since the settle down of the relaxion needs to take place during inflation. In this paper, unlike the original one, we consider another scenario in which the Higgs vacuum expectation value is determined after inflation. To accomplish the mechanism, we take into account the effects of the Hubble-induced mass and thermal one in the dynamics of the relaxion. Then, we find that for the relaxion mechanism the coupling of the relaxion with the additional mass terms should be large.
Code of Federal Regulations, 2013 CFR
2013-10-01
... apparatus, inflatable life jackets, and inflated rescue boats. 185.730 Section 185.730 Shipping COAST GUARD... liferafts, inflatable buoyant apparatus, inflatable life jackets, and inflated rescue boats. (a) An... inflated rescue boats must be in accordance with the manufacturer's instructions. All repairs must be...
Code of Federal Regulations, 2012 CFR
2012-10-01
... lifejackets, inflatable buoyant apparatus, and inflated rescue boats. 131.580 Section 131.580 Shipping COAST..., and inflated rescue boats. (a) An inflatable liferaft or inflatable buoyant apparatus must be serviced... maintenance of inflatable rescue boats must follow the manufacturers' instructions. Each repair, except...
Code of Federal Regulations, 2014 CFR
2014-10-01
... lifejackets, inflatable buoyant apparatus, and inflated rescue boats. 131.580 Section 131.580 Shipping COAST..., and inflated rescue boats. (a) An inflatable liferaft or inflatable buoyant apparatus must be serviced... maintenance of inflatable rescue boats must follow the manufacturers' instructions. Each repair, except...
Code of Federal Regulations, 2012 CFR
2012-10-01
... apparatus, inflatable life jackets, and inflated rescue boats. 185.730 Section 185.730 Shipping COAST GUARD... liferafts, inflatable buoyant apparatus, inflatable life jackets, and inflated rescue boats. (a) An... inflated rescue boats must be in accordance with the manufacturer's instructions. All repairs must be...
Code of Federal Regulations, 2013 CFR
2013-10-01
... lifejackets, inflatable buoyant apparatus, and inflated rescue boats. 131.580 Section 131.580 Shipping COAST..., and inflated rescue boats. (a) An inflatable liferaft or inflatable buoyant apparatus must be serviced... maintenance of inflatable rescue boats must follow the manufacturers' instructions. Each repair, except...
Code of Federal Regulations, 2014 CFR
2014-10-01
... apparatus, inflatable life jackets, and inflated rescue boats. 185.730 Section 185.730 Shipping COAST GUARD... liferafts, inflatable buoyant apparatus, inflatable life jackets, and inflated rescue boats. (a) An... inflated rescue boats must be in accordance with the manufacturer's instructions. All repairs must be...
NASA Technical Reports Server (NTRS)
Krauss, L. M.; Guth, A. H.; Spergel, D. N.; Field, G. B.; Press, W. H.
1986-01-01
The possible production of shadow matter during the period of cosmic inflation is considered. The superstring theory of Gross et al. (1985), which results in a gauge group E8 x E8, could, at low energies, result in the existence of two sectors: an observed sector associated with all familiar particles and interactions, and a hidden one whose particles couple only through gravitational interactions with ordinary matter. It is demonstrated here that if, in the early universe, an inflationary phase is associated with the breaking of one of the symmetries in the E8 x E8 theory, this strongly constrains the physics of both sectors if shadow matter is to be the missing mass in the universe.
Beginning of Universe through large field hybrid inflation
NASA Astrophysics Data System (ADS)
Kobayashi, Tatsuo; Seto, Osamu
2015-06-01
Recent detection of B-mode polarization induced from tensor perturbations by the BICEP2 experiment implies the so-called large field inflation, where an inflaton field takes super-Planckian expectation value during inflation, at a high energy scale. We show however, if another inflation follows hybrid inflation, the hybrid inflation can generate a large tensor perturbation with not super-Planckian but Planckian field value. This scenario would relax the tension between BICEP2 and Planck concerning the tensor-to-scalar ratio, because a negative large running can also be obtained for a certain number of e-fold of the hybrid inflation. A natural interpretation of a large gravitational wave mode with or without the scalar spectral running might be multiple inflation in the early Universe.
Beyond Inflation: A Cyclic Universe Scenario
NASA Astrophysics Data System (ADS)
Turok, Neil; Steinhardt, Paul J.
2005-01-01
Inflation has been the leading early universe scenario for two decades, and has become an accepted element of the successful `cosmic concordance' model. However, there are many puzzling features of the resulting theory. It requires both high energy and low energy inflation, with energy densities differing by a hundred orders of magnitude. The questions of why the universe started out undergoing high energy inflation, and why it will end up in low energy inflation, are unanswered. Rather than resort to anthropic arguments, we have developed an alternative cosmology, the cyclic universe, in which the universe exists in a very long-lived attractor state determined by the laws of physics. The model shares inflation's phenomenological successes without requiring an epoch of high energy inflation. Instead, the universe is made homogeneous and flat, and scale-invariant adiabatic perturbations are generated during an epoch of low energy acceleration like that seen today, but preceding the last big bang. Unlike inflation, the model requires low energy acceleration in order for a periodic attractor state to exist. The key challenge facing the scenario is that of passing through the cosmic singularity at t = 0. Substantial progress has been made at the level of linearised gravity, which is reviewed here. The challenge of extending this to nonlinear gravity and string theory remains.
Beyond Inflation:. A Cyclic Universe Scenario
NASA Astrophysics Data System (ADS)
Turok, Neil; Steinhardt, Paul J.
2005-08-01
Inflation has been the leading early universe scenario for two decades, and has become an accepted element of the successful 'cosmic concordance' model. However, there are many puzzling features of the resulting theory. It requires both high energy and low energy inflation, with energy densities differing by a hundred orders of magnitude. The questions of why the universe started out undergoing high energy inflation, and why it will end up in low energy inflation, are unanswered. Rather than resort to anthropic arguments, we have developed an alternative cosmology, the cyclic universe [1], in which the universe exists in a very long-lived attractor state determined by the laws of physics. The model shares inflation's phenomenological successes without requiring an epoch of high energy inflation. Instead, the universe is made homogeneous and flat, and scale-invariant adiabatic perturbations are generated during an epoch of low energy acceleration like that seen today, but preceding the last big bang. Unlike inflation, the model requires low energy acceleration in order for a periodic attractor state to exist. The key challenge facing the scenario is that of passing through the cosmic singularity at t = 0. Substantial progress has been made at the level of linearised gravity, which is reviewed here. The challenge of extending this to nonlinear gravity and string theory remains.
Inflation, Reionization, and All That: The Primordial Inflation Explorer
NASA Technical Reports Server (NTRS)
Kogut, Alan J.
2011-01-01
The Primordial Inflation Explorer is an Explorer-class mission to measure the gravity-wave signature of primordial inflation through its distinctive imprint on the linear polarization of the cosmic microwave background. PIXIE uses an innovative optical design to achieve background-limited sensitivity in 400 spectral channels spanning 2.5 decades in frequency from 30 GHz to 6 THz (1 cm to 50 micron wavelength). The principal science goal is the detection and characterization of linear polarization from an inflationary epoch in the early universe, with tensor-to-scalar ratio r less than l0^{-3) at 5 standard deviations. The rich PIXIE data set will also constrain physical processes ranging from Big Bang cosmology to the nature of the first stars to physical conditions within the interstellar medium of the Galaxy. I describe the PIXIE instrument and mission architecture needed to detect the inflationary signature using only 4 semiconductor bolometers.
Inflation, Reionization, and All That: The Primordial Inflation Explorer
NASA Technical Reports Server (NTRS)
Kogut, Alan J.
2012-01-01
The Primordial Inflation Explorer is an Explorer-class mission to measure the gravity-wave signature of primordial inflation through its distinctive imprint on the linear polarization of the cosmic microwave background. PIXIE uses an innovative optical design to achieve background-limited sensitivity in 400 spectral channels spanning 2.5 decades in frequency from 30 GHz to 6 THz (1 cm to 50 micron wavelength). The principal science goal is the detection and characterization of linear polarization from an inflationary epoch in the early universe, with tensor-to-scalar ratio r < 10(exp -3) at 5 standard deviations. The rich PIXIE data set will also constrain physical processes ranging from Big Bang cosmology to the nature of the first stars to physical conditions within the interstellar medium of the Galaxy. I describe the PIXIE instrument and mission architecture needed to detect the inflationary signature using only 4 semiconductor bolometers.
Inflatable nested toroid structure
NASA Technical Reports Server (NTRS)
Johnson, Christopher J. (Inventor); Raboin, Jasen L. (Inventor); Spexarth, Gary R. (Inventor)
2011-01-01
An inflatable structure comprises at least two generally toroidal, inflatable modules. When in a deployed mode, the first, inner module has a major diameter less than that of a second, outer module and is positioned within the inner circumference of the outer module such that the first module is nested circumferentially alongside the second module. The inflatable structure, in a non-deployed, non-inflated mode, is of compact configuration and adapted to be transported to a site of deployment. When deployed, the inflatable structure is of substantially increased interior volume. In one embodiment, access between the interior of the first module and the second module is provided by at least one port or structural pass-through. In another embodiment, the inflatable structure includes at least one additional generally toroidal module external of and circumferentially surrounding the second module.
Graceful entrance to braneworld inflation
Lidsey, James E.; Mulryne, David J.
2006-04-15
Positively-curved, oscillatory universes have recently been shown to have important consequences for the preinflationary dynamics of the early universe. In particular, they may allow a self-interacting scalar field to climb up its potential during a very large number of these cycles. The cycles are naturally broken when the potential reaches a critical value and the universe begins to inflate, thereby providing a 'graceful entrance' to early universe inflation. We study the dynamics of this behavior within the context of braneworld scenarios which exhibit a bounce from a collapsing phase to an expanding one. The dynamics can be understood by studying a general class of braneworld models that are sourced by a scalar field with a constant potential. Within this context, we determine the conditions a given model must satisfy for a graceful entrance to be possible in principle. We consider the bouncing braneworld model proposed by Shtanov and Sahni and show that it exhibits the features needed to realise a graceful entrance to inflation for a wide region of parameter space.
Barenboim, Gabriela; Park, Wan-Il E-mail: Wanil.Park@uv.es
2016-02-01
We show that ''spiralized' models of new-inflation can be experimentally identified mostly by their positive spectral running in direct contrast with most chaotic-inflation models which have negative runnings typically in the range of O(10{sup −4}–10{sup −3})
ERIC Educational Resources Information Center
Pitt, David
Inflation is both a cause and consequence of changes in power and status. Competitive status activities create spiral situations which have an economic correlate. Ultimately, inflation leads to the creation of economically deprived and depressed social groups. Deflation can be achieved to some extent by redistribution of wealth dictated from…
Inflation of Conditional Predictions
ERIC Educational Resources Information Center
Koriat, Asher; Fiedler, Klaus; Bjork, Robert A.
2006-01-01
The authors report 7 experiments indicating that conditional predictions--the assessed probability that a certain outcome will occur given a certain condition--tend to be markedly inflated. The results suggest that this inflation derives in part from backward activation in which the target outcome highlights aspects of the condition that are…
Inflation in inhomogeneous cosmology
NASA Astrophysics Data System (ADS)
Calzetta, Esteban; Sakellariadou, Maria
1992-04-01
We discuss the onset of inflation in an inhomogeneous, asymptotically Friedmann-Robertson-Walker universe coupled to a scalar inflaton field. We consider a three-parameter family of inhomogeneous Cauchy data, for which we can solve analytically the constraint equations. Inflation only occurs if the Cauchy data are homogeneous over several horizon lengths.
Ponden, Raymond F.
1991-11-22
Inflation of the reservoir is to begin on Friday afternoon, November 22 and continue through mid day on Monday, November 25. Inflation of the reservoir shall be accomplished by using only injection pump, HP-2. NOTE: Under no circumstances should injection pump, HP-1 be operated.
Chiral primordial gravitational waves from dilaton induced delayed chromonatural inflation
NASA Astrophysics Data System (ADS)
Obata, Ippei; Soda, Jiro; CLEO Collaboration
2016-06-01
We study inflation driven by a dilaton and an axion, both of which are coupled to a SU(2) gauge field. We find that the inflation driven by the dilaton occurs in the early stage of inflation during which the gauge field grows due to the gauge-kinetic function. When the energy density of magnetic fields catches up with that of electric fields, chromonatural inflation takes over in the late stage of inflation, which we call delayed chromonatural inflation. Thus, the delayed chromonatural inflation driven by the axion and the gauge field is induced by the dilaton. The interesting outcome of the model is the generation of chiral primordial gravitational waves on small scales. Since the gauge field is inert in the early stage of inflation, it is viable in contrast to the conventional chromonatural inflation. We find the parameter region where chiral gravitational waves are generated in a frequency range higher than nHz, which are potentially detectable in future gravitational wave interferometers and pulsar-timing arrays such as DECi-hertz Interferometer Gravitational wave Observatory (DECIGO), evolved Laser Interferometer Space Antenna (eLISA), and Square Kilometer Array (SKA).
The Primordial Inflation Explorer (PIXIE)
NASA Technical Reports Server (NTRS)
Kogut, Alan; Chuss, David T.; Dotson, Jessie; Dwek, Eli; Fixsen, Dale J.; Halpern, Mark; Hinshaw, Gary F.; Meyer, Stephan; Moseley, S. Harvey; Seiffert, Michael D.; Spergel, David N.; Wollack, Edward J.
2014-01-01
The Primordial Inflation Explorer is an Explorer-class mission to measure the gravity-wave signature of primordial inflation through its distinctive imprint on the linear polarization of the cosmic microwave background. PIXIE uses an innovative optical design to achieve background-limited sensitivity in 400 spectral channels spanning 2.5 decades in frequency from 30 GHz to 6 THz (1 cm to 50 micron wavelength). Multi-moded non-imaging optics feed a polarizing Fourier Transform Spectrometer to produce a set of interference fringes, proportional to the difference spectrum between orthogonal linear polarizations from the two input beams. Multiple levels of symmetry and signal modulation combine to reduce the instrumental signature and confusion from unpolarized sources to negligible levels. PIXIE will map the full sky in Stokes I, Q, and U parameters with angular resolution 2.6 deg and sensitivity 0.2 µK per 1 deg square pixel. The principal science goal is the detection and characterization of linear polarization from an inflationary epoch in the early universe, with tensor-to-scalar ratio r less than 10(exp -3) at 5 standard deviations. In addition, PIXIE will measure the absolute frequency spectrum to constrain physical processes ranging from inflation to the nature of the first stars to the physical conditions within the interstellar medium of the Galaxy. We describe the PIXIE instrument and mission architecture with an emphasis on the expected level of systematic error suppression.
Development of an Inflatable Head/Neck Restraint System for Ejection Seats
1977-02-28
Report) 10 SUPPLEMENTARY NOTES 19 KEY WORDS fConrinuo an fevers& Bide If neceesary antd Identify by block number) Inflatable neck collar Inflatable...TABLE, Anthropometric Measurements Pertaining to Neck Collar Design .............. ... ............................ 11 1. - 1- IV NADC...3 Layout of Inflation System Components ......... ............ 9 4 An Early Neck Collar Design - Three Layer Neck •ingt’.* . 12 Sa
Inflation, inflation uncertainty and output growth in the USA
NASA Astrophysics Data System (ADS)
Bhar, Ramprasad; Mallik, Girijasankar
2010-12-01
Employing a multivariate EGARCH-M model, this study investigates the effects of inflation uncertainty and growth uncertainty on inflation and output growth in the United States. Our results show that inflation uncertainty has a positive and significant effect on the level of inflation and a negative and significant effect on the output growth. However, output uncertainty has no significant effect on output growth or inflation. The oil price also has a positive and significant effect on inflation. These findings are robust and have been corroborated by use of an impulse response function. These results have important implications for inflation-targeting monetary policy, and the aim of stabilization policy in general.
The inflation sector of extended inflation
Kolb, E.W. Chicago Univ., IL )
1990-11-01
In extended inflation the inflationary era is brought to a close by the process of percolation of true vacuum bubbles produced in a first-order phase transition. In this paper I discuss several effects that might obtain if the Universe undergoes an inflationary first-order phase transition. 17 refs.
Croon, Djuna; Sanz, Verónica E-mail: v.sanz@sussex.ac.uk
2015-02-01
Slow-roll inflation requires the inflaton field to have an exceptionally flat potential, which combined with measurements of the scale of inflation demands some degree of fine-tuning. Alternatively, the flatness of the potential could be due to the inflaton's origin as a pseudo-Goldstone boson, as in Natural Inflation. Alas, consistency with Planck data places the original proposal of Natural Inflation in a tight spot, as it requires a trans-Planckian excursion of the inflaton. Although one can still tune the renormalizable potential to sub-Planckian values, higher order corrections from quantum gravity or sources of breaking of the Goldstone symmetry would ruin the predictivity of the model. In this paper we show how in more realistic models of Natural Inflation one could achieve inflation without a trans-Planckian excursion of the field. We show how a variant of Extra-natural inflation with bulk fermions can achieve the desired goal and discuss its four-dimensional duals. We also present a new type of four dimensional models inspired in Little Higgs and Composite Higgs models which can lead to sub-Planckian values of the inflaton field.
Probing Inflation via Cosmic Microwave Background Polarimetry
NASA Technical Reports Server (NTRS)
Chuss, David T.
2008-01-01
The Cosmic Microwave Background (CMB) has been a rich source of information about the early Universe. Detailed measurements of its spectrum and spatial distribution have helped solidify the Standard Model of Cosmology. However, many questions still remain. Standard Cosmology does not explain why the early Universe is geometrically flat, expanding, homogenous across the horizon, and riddled with a small anisotropy that provides the seed for structure formation. Inflation has been proposed as a mechanism that naturally solves these problems. In addition to solving these problems, inflation is expected to produce a spectrum of gravitational waves that will create a particular polarization pattern on the CMB. Detection of this polarized signal is a key test of inflation and will give a direct measurement of the energy scale at which inflation takes place. This polarized signature of inflation is expected to be -9 orders of magnitude below the 2.7 K monopole level of the CMB. This measurement will require good control of systematic errors, an array of many detectors having the requisite sensitivity, and a reliable method for removing polarized foregrounds, and nearly complete sky coverage. Ultimately, this measurement is likely to require a space mission. To this effect, technology and mission concept development are currently underway.
Magnetic fields from inflation?
Demozzi, Vittoria; Mukhanov, Viatcheslav; Rubinstein, Hector E-mail: viatcheslav.mukhanov@physik.uni-muenchen.de
2009-08-01
We consider the possibility of generation of the primordial magnetic field on inflation and show that the effect of the back reaction of this field can be very important. Assuming that the back reaction does not spoil inflation we find a rather strong restriction on the amplitude of the primordial field which could be generated on inflation. Namely, this amplitude recalculated to the present epoch cannot exceed 10{sup −32}G in Mpc scales. This field seems to be too small to be amplified to the observable values by a possible dynamo mechanism.
NASA Astrophysics Data System (ADS)
Ballesteros, Guillermo; Tamarit, Carlos
2016-02-01
We describe how monomial chaotic inflation becomes compatible with the latest CMB data thanks to radiative corrections producing a plateau. The interactions of the inflaton with other fields, required for reheating, can flatten the potential and moderate the production of primordial gravitational waves, keeping these below the current upper bound. We show that the appearance of a plateau requires that the inflaton couples to fermions and to another scalar or a gauge group. We give concrete examples of minimal particle physics models leading to plateaus for quadratic and quartic chaotic inflation. We also provide a three-parameter model-independent description of radiatively corrected inflation that is amenable to CMB analyses.
Code of Federal Regulations, 2011 CFR
2011-10-01
... Inspection of Lifesaving Equipment § 122.730 Servicing of inflatable liferafts, inflatable buoyant apparatus... apparatus must be serviced at a facility specifically approved by the Commandant for the particular brand... apparatus, inflatable life jackets, and inflated rescue boats. 122.730 Section 122.730 Shipping COAST...
Code of Federal Regulations, 2010 CFR
2010-10-01
... Inspection of Lifesaving Equipment § 122.730 Servicing of inflatable liferafts, inflatable buoyant apparatus... apparatus must be serviced at a facility specifically approved by the Commandant for the particular brand... apparatus, inflatable life jackets, and inflated rescue boats. 122.730 Section 122.730 Shipping COAST...
Code of Federal Regulations, 2010 CFR
2010-10-01
... inflatable liferaft or inflatable buoyant apparatus must be serviced at a facility specifically approved by... apparatus, inflatable life jackets, and inflated rescue boats. 185.730 Section 185.730 Shipping COAST GUARD... Operational Readiness, Maintenance, and Inspection of Lifesaving Equipment § 185.730 Servicing of...
Code of Federal Regulations, 2011 CFR
2011-10-01
... inflatable liferaft or inflatable buoyant apparatus must be serviced at a facility specifically approved by... apparatus, inflatable life jackets, and inflated rescue boats. 185.730 Section 185.730 Shipping COAST GUARD... Operational Readiness, Maintenance, and Inspection of Lifesaving Equipment § 185.730 Servicing of...
NASA Now: Inflatable Structures
NASA senior research engineer Judith Watson is one of a team of engineers at NASAâs Langley Research Center who are studying inflatable structures that might one day be used to establish an outpo...
Tribrid Inflation in Supergravity
Antusch, Stefan; Dutta, Koushik; Kostka, Philipp M.
2010-02-10
We propose a novel class of F-term hybrid inflation models in supergravity (SUGRA) where the eta-problem is resolved using either a Heisenberg symmetry or a shift symmetry of the Kaehler potential. In addition to the inflaton and the waterfall field, this class (referred to as tribrid inflation) contains a third 'driving' field which contributes the large vacuum energy during inflation by its F-term. In contrast to the 'standard' hybrid scenario, it has several attractive features due to the property of vanishing inflationary superpotential (W{sub inf} = 0) during inflation. While the symmetries of the Kaehler potential ensure a flat inflaton potential at tree-level, quantum corrections induced by symmetry breaking terms in the superpotential generate a slope of the potential and lead to a spectral tilt consistent with recent WMAP observations.
Inflatable traversing probe seal
NASA Technical Reports Server (NTRS)
Trimarchi, Paul A.
1991-01-01
An inflatable seal acts as a pressure-tight zipper to provide traversing capability for instrumentation rakes and probes. A specially designed probe segment with a teardrop cross-section in the vicinity of the inflatable seal minimizes leakage at the interface. The probe is able to travel through a lengthwise slot in a pressure vessel or wind tunnel section, while still maintaining pressure integrity. The design uses two commercially available inflatable seals, opposing each other, to cover the probe slot in a wind tunnel wall. Proof-of-concept tests were conducted at vessel pressures up to 30 psig, with seals inflated to 50 psig, showing no measurable leakage along the seal's length or around the probe teardrop cross-section. This seal concept can replace the existing technology of sliding face plate/O-ring systems in applications where lengthwise space is limited.
Inflatable artificial sphincter - slideshow
... presentations/100115.htm Inflatable artificial sphincter - series—Normal anatomy To use the sharing features on this page, ... Bethesda, MD 20894 U.S. Department of Health and Human Services National Institutes of Health Page last updated: ...
NASA Technical Reports Server (NTRS)
Holman, Richard; Kolb, Edward W.; Vadas, Sharon L.; Wang, Yun
1991-01-01
It is likely that extended inflation is followed by an epoch of slowroll inflation. Such a sequence of events may lead to a very interesting perturbation spectrum with significant power on the scale of the transition between the extended and slowroll phase, superimposed upon a power-law spectrum with deviations from the Harrison-Zeldovich slope. Normalization of the spectra above and below the transition scale is expected to differ.
Warm inflation in presence of magnetic fields
Piccinelli, Gabriella; Ayala, Alejandro; Mizher, Ana Julia
2013-07-23
We present preliminary results on the possible effects that primordial magnetic fields can have for a warm inflation scenario, based on global supersymmetry, with a new-inflation-type potential. This work is motivated by two considerations: first, magnetic fields seem to be present in the universe on all scales which rises de possibility that they could also permeate the early universe; second, the recent emergence of inflationary models where the inflaton is not assumed to be isolated but instead it is taken as an interacting field, even during the inflationary expansion. The effects of magnetic fields are included resorting to Schwinger's proper time method.
Inflation Driven by q-de Sitter
NASA Astrophysics Data System (ADS)
Setare, M. R.; Momeni, D.; Kamali, V.; Myrzakulov, R.
2016-02-01
We propose a generalised de Sitter scale factor for the cosmology of early and late time universe, including single scalar field is called as inflaton. This form of scale factor has a free parameter q is called as nonextensivity parameter. When q = 1, the scale factor is de Sitter. This scale factor is an intermediate form between power-law and de Sitter. We study cosmology of such families. We show that both kinds of dark components, dark energy and dark matter simultaneously are described by this family of solutions. As a motivated idea, we investigate inflation in the framework of q-de Sitter. We consider three types of scenarios for inflation. In a single inflation scenario, we observe that, inflation ended without any specific ending inflation ϕ e n d , the spectral index and the associated running of the spectral index are n s - 1 ˜ -2 𝜖, α s ≡ 0. To end the inflation: we should have q={3}/{4}. We deduce that the inflation ends when the evolution of the scale factor is a( t) = e 3/4( t). With this scale factor there is no need to specify ϕ e n d . As an alternative to have inflation with ending point, We will study q-inflation model in the context of warm inflation. We propose two forms of damping term Γ. In the first case when Γ = Γ0, we show the scale invariant spectrum, (Harrison-Zeldovich spectrum, i.e. n s = 1) may be approximately presented by (q={9}/{10}, ~N=70). Also there is a range of values of R and n s which is compatible with the BICEP2 data where q={9}/{10}. In case Γ = Γ1 V( ϕ), it is observed that small values of a number of e-folds are assured for small values of q parameter. Also in this case, the scale-invariant spectrum may be represented by (q,N) = ({9}/{10},70). For q={9}/{10} a range of values of R and n s is compatible with the BICEP2 data. Consequently, the proposal of q-de Sitter is consistent with observational data. We observe that the non-extensivity parameter q plays a significant role in inflationary scenario.
The Primordial Inflation Explorer (PIXIE)
NASA Technical Reports Server (NTRS)
Kogut, Alan J.
2011-01-01
The Primordial Inflation Explorer is an Explorer-class mission to measure the gravity-wave signature of primordial inflation through its distinctive imprint on the linear polarization of the cosmic microwave background. PIXIE uses an innovative optical design to achieve background-limited sensitivity in 400 spectral channels spanning 2.5 decades in frequency from 30 GHz to 6 THz (1 cm to 50 micron wavelength). Multi-moded non-imaging optics feed a polarizing Fourier Transform Spectrometer to produce a set of interference fringes, proportional to the difference spectrum between orthogonal linear polarizations from the two input beams. The differential design and multiple signal modulations spanning 11 orders of magnitude in time combine to reduce the instrumental signature and confusion from unpolarized sources to negligible levels. PIXIE will map the full sky in Stokes I, Q, and U parameters with angular resolution 2.6 deg and sensitivity 0.2 uK per 1 deg square pixel. The principal science goal is the detection and characterization of linear polarization from an inflationary epoch in the early universe, with tensor-to-scalar ratio r <10(exp -3) at 5 standard deviations. In addition, the rich PIXIE data will constrain physical processes ranging from Big Bang cosmology to the nature of the first stars to the physical conditions within the interstellar medium of the Galaxy. We describe the PIXIE instrument and mission architecture needed to detect the signature of an inflationary epoch in the early universe using only 4 semiconductor bolometers.
Cosmic Microwave Background Polarization and Inflation
NASA Technical Reports Server (NTRS)
Chuss, David T.
2011-01-01
Measurements of the cosmic microwave background (CMB) offer a means to explore the universe at a very early epoch. Specifically, if the universe went through a brief period of exponential expansion called inflation as current data suggest, gravitational waves from this period would polarize the CMB in a specific pattern. At GSFC, we are currently working towards two experiments that work in concert to measure this polarization pattern in search of evidence for inflation. The Cosmology Large Angular Scale Surveyor (CLASS) will measure the polarization at frequencies between 40 and 150 GHz from the Atacama Desert in Chile. The Primordial Inflation Polarization Explorer (PIPER) is a balloon-borne experiment that will make similar measurements at frequencies between 200 and 600 GHz.
NASA Astrophysics Data System (ADS)
Huang, Qing-Guo
In this paper, I will give a brief overview of the physics in the early universe, in particular, the inflation scenario. The predictions and the latest constraints on the inflation models will be discussed in detail.
Bartolo, Nicola; Matarrese, Sabino; Ricciardone, Angelo; Peloso, Marco E-mail: sabino.matarrese@pd.infn.it E-mail: angelo.ricciardone@pd.infn.it
2013-08-01
In the model of solid / elastic inflation, inflation is driven by a source that has the field theoretical description of a solid. To allow for prolonged slow roll inflation, the solid needs to be extremely insensitive to the spatial expansion. We point out that, because of this property, the solid is also rather inefficient in erasing anisotropic deformations of the geometry. This allows for a prolonged inflationary anisotropic solution, providing the first example with standard gravity and scalar fields only which evades the conditions of the so called cosmic no-hair conjecture. We compute the curvature perturbations on the anisotropic solution, and the corresponding phenomenological bound on the anisotropy. Finally, we discuss the analogy between this model and the f(φ)F{sup 2} model, which also allows for anisotropic inflation thanks to a suitable coupling between the inflaton φ and a vector field. We remark that the bispectrum of the curvature perturbations in solid inflation is enhanced in the squeezed limit and presents a nontrivial angular dependence, as had previously been found for the f(φ)F{sup 2} model.
NASA Astrophysics Data System (ADS)
Bartolo, Nicola; Matarrese, Sabino; Peloso, Marco; Ricciardone, Angelo
2013-08-01
In the model of solid / elastic inflation, inflation is driven by a source that has the field theoretical description of a solid. To allow for prolonged slow roll inflation, the solid needs to be extremely insensitive to the spatial expansion. We point out that, because of this property, the solid is also rather inefficient in erasing anisotropic deformations of the geometry. This allows for a prolonged inflationary anisotropic solution, providing the first example with standard gravity and scalar fields only which evades the conditions of the so called cosmic no-hair conjecture. We compute the curvature perturbations on the anisotropic solution, and the corresponding phenomenological bound on the anisotropy. Finally, we discuss the analogy between this model and the f(phi)F2 model, which also allows for anisotropic inflation thanks to a suitable coupling between the inflaton phi and a vector field. We remark that the bispectrum of the curvature perturbations in solid inflation is enhanced in the squeezed limit and presents a nontrivial angular dependence, as had previously been found for the f(phi)F2 model.
Aerocapture Inflatable Decelerator (AID)
NASA Technical Reports Server (NTRS)
Reza, Sajjad
2007-01-01
Forward Attached Inflatable Decelerators, more commonly known as inflatable aeroshells, provide an effective, cost efficient means of decelerating spacecrafts by using atmospheric drag for aerocapture or planetary entry instead of conventional liquid propulsion deceleration systems. Entry into planetary atmospheres results in significant heating and aerodynamic pressures which stress aeroshell systems to their useful limits. Incorporation of lightweight inflatable decelerator surfaces with increased surface-area footprints provides the opportunity to reduce heat flux and induced temperatures, while increasing the payload mass fraction. Furthermore, inflatable aeroshell decelerators provide the needed deceleration at considerably higher altitudes and Mach numbers when compared with conventional rigid aeroshell entry systems. Inflatable aeroshells also provide for stowage in a compact space, with subsequent deployment of a large-area, lightweight heatshield to survive entry heating. Use of a deployable heatshield decelerator not only enables an increase in the spacecraft payload mass fraction and but may also eliminate the need for a spacecraft backshell and cruise stage. This document is the viewgraph slides for the paper's presentation.
Grade inflation: a problem in nursing?
King-Jones, Malena; Mitchell, Abigail
2012-01-01
This article examines grade inflation in higher education and in nursing education. The factors related to grade inflation and consequences of grade inflation are explored. Actions that address grade inflation and recommendations for future research in nursing education are provided.
Mars inflatable greenhouse analog.
Sadler, Philip D; Giacomelli, Gene A
2002-01-01
Light intensities on the Martian surface can possibly support a bioregenerative life support system (BLSS) utilizing natural sunlight for hydroponic crop production, if a suitable controlled environment can be provided. Inflatable clear membrane structures offer low mass, are more easily transported than a rigid structure, and are good candidates for providing a suitable controlled environment for crop production. Cable culture is one hydroponic growing system that can take advantage of the beneficial attributes of the inflatable structure. An analog of a Mars inflatable greenhouse can provide researchers data on issues such as crew time requirements for operation, productivity for BLSS, human factors, and much more at a reasonable cost. This is a description of one such design.
Inflation from geometrical tachyons
Thomas, Steven; Ward, John
2005-10-15
We propose an alternative formulation of tachyon inflation using the geometrical tachyon arising from the time dependent motion of a BPS D3-brane in the background geometry due to k parallel NS5-branes arranged around a ring of radius R. Because of the fact that the mass of this geometrical tachyon field is {radical}(2/k) times smaller than the corresponding open-string tachyon mass, we find that the slow-roll conditions for inflation and the number of e-foldings can be satisfied in a manner that is consistent with an effective 4-dimensional model and with a perturbative string coupling. We also show that the metric perturbations produced at the end of inflation can be sufficiently small and do not lead to the inconsistencies that plague the open-string tachyon models. Finally we argue for the existence of a minimum of the geometrical tachyon potential which could give rise to a traditional reheating mechanism.
Ellis, John; Gonzalo, Tomás E.; Harz, Julia; Huang, Wei-Chih
2015-03-23
We analyse the prospects for constructing hybrid models of inflation that provide a dynamical realisation of the apparent closeness between the supersymmetric GUT scale and the possible scale of cosmological inflation. In the first place, we consider models based on the flipped SU(5)×U(1) gauge group, which has no magnetic monopoles. In one model, the inflaton is identified with a sneutrino field, and in the other model it is a gauge singlet. In both cases we find regions of the model parameter spaces that are compatible with the experimental magnitudes of the scalar perturbations, A{sub s}, and the tilt in the scalar perturbation spectrum, n{sub s}, as well as with an indicative upper limit on the tensor-to-scalar perturbation ratio, r. We also discuss embeddings of these models into SO(10), which is broken at a higher scale so that its monopoles are inflated away.
De Bruck, Carsten van; Longden, Chris; Koivisto, Tomi E-mail: timoko@kth.se
2016-03-01
A disformal coupling between two scalar fields is considered in the context of cosmological inflation. The coupling introduces novel derivative interactions mixing the kinetic terms of the fields but without introducing superluminal or unstable propagation of the two scalar fluctuation modes. Though the typical effect of the disformal coupling is to inhibit one of the fields from inflating the universe, the energy density of the other field can drive viable near Sitter -inflation in the presence of nontrivial disformal dynamics, in particular when one assumes exponential instead of power-law form for the couplings. The linear perturbation equations are written for the two-field system, its canonical degrees of freedom are quantised, their spectra are derived and the inflationary predictions are reported for numerically solved exponential models. A generic prediction is low tensor-to-scalar ratio.
Developing an Inflatable Solar Array
NASA Technical Reports Server (NTRS)
Malone, Patrick K.; Jankowski, Francis J.; Williams, Geoffery T.; Vendura, George J., Jr.
1992-01-01
Viewgraphs describing the development of an inflatable solar array as part of the Inflatable Torus Solar Array Technology (ITSAT) program are presented. Program phases, overall and subsystem designs, and array deployment are addressed.
Grade Inflation: Metaphor and Reality
ERIC Educational Resources Information Center
Kamber, Richard; Biggs, Mary
2003-01-01
Grade inflation has become a general term for teachers and administrators in recent times and is an ambiguous denomination which needs to be identified. The allegory and reality of grade inflation is discussed.
Inflation and cyclotron motion
NASA Astrophysics Data System (ADS)
Greensite, Jeff
2017-01-01
We consider, in the context of a braneworld cosmology, the motion of the Universe coupled to a four-form gauge field, with constant field strength, defined in higher dimensions. It is found, under rather general initial conditions, that in this situation there is a period of exponential inflation combined with cyclotron motion in the inflaton field space. The main effect of the cyclotron motion is that slow roll conditions on the inflaton potential, which are typically necessary for exponential inflation, can be evaded. There are Landau levels associated with the four-form gauge field, and these correspond to quantum excitations of the inflaton field satisfying unconventional dispersion relations.
Topological defects in extended inflation
NASA Technical Reports Server (NTRS)
Copeland, Edmund J.; Kolb, Edward W.; Liddle, Andrew R.
1990-01-01
The production of topological defects, especially cosmic strings, in extended inflation models was considered. In extended inflation, the Universe passes through a first-order phase transition via bubble percolation, which naturally allows defects to form at the end of inflation. The correlation length, which determines the number density of the defects, is related to the mean size of bubbles when they collide. This mechanism allows a natural combination of inflation and large scale structure via cosmic strings.
Cosmological Inflation: A Personal Perspective
NASA Technical Reports Server (NTRS)
Kazanas, D.
2007-01-01
Approximately twenty five years ago a novel proposal was made to explain two of the outstanding cosmological conundrums, namely those of the Horizon Problem and the Flatness Problem of the Universe. These are the fact that widely separated parts of the sky that have never been in causal contact during the evolution of the Universe have apparently the same CMB temperature and the fact that the mean density of the Universe is very close to the critical one, i.e. very close to the density that separates the closed and open models. These coincidences implied that the corresponding initial condition of the Universe must have been set to exquisite accuracy. This novel proposal posted that at these very early times, the energy density of the Universe was dominated by a fluid which had the equation state attributed to the vacuum (i.e. dominated by tension rather than pressure) and that this led to an exponential expansion of the Universe which was "inflated" by many orders of magnitude of its original size. It was then shown that this "inflation" could provide a resolution of the above outstanding problems. The talk will cover the speaker's personal perspective and contributions to this idea and the subsequent developments over the following 25 years since its inception.
Pneumatic inflatable end effector
NASA Technical Reports Server (NTRS)
Clark, K. H.; Johnston, J. D. (Inventor)
1981-01-01
The invention relates to an end effector device for robot or teleoperated type space vehicle which includes an inflatable balloon member carried on the end of tubular member which has a hollow center or conduit through which a suitable pressurized fluid is supplied. The device may be inserted into a variety of shaped openings or truss-type structures for handling in space.
NASA Astrophysics Data System (ADS)
Jeannerot, Rachel; Khalil, Shaaban; Lazarides, George
2002-07-01
A new shifted hybrid inflationary scenario is introduced which, in contrast to the older one, relies only on renormalizable superpotential terms. This scenario is automatically realized in a concrete extension of the `minimal' supersymmetric Pati-Salam model which naturally leads to a moderate violation of Yukawa unification so that, for μ>0, the predicted b-quark mass is acceptable even with universal boundary conditions. It is shown that this extended model possesses a classically flat `shifted' trajectory which acquires a slope via one-loop radiative corrections and can be used as inflationary path. The constraints from the cosmic background explorer can be met with natural values of the relevant parameters. Also, there is no disastrous production of magnetic monopoles after inflation since the Pati-Salam gauge group is already broken on the `shifted' path. The relevant part of inflation takes place at values of the inflaton field which are not much smaller than the `reduced' Planck scale and, thus, supergravity corrections could easily invalidate inflation. It is, however, shown that inflation can be kept intact provided that an extra gauge singlet with a superheavy vacuum expectation value, which originates from D-terms, is introduced and a specific form of the Kähler potential is used. Moreover, it is found that, although the supergravity corrections are sizable, the constraints from the cosmic background explorer can again be met by readjusting the values of the parameters which were obtained with global supersymmetry.
ERIC Educational Resources Information Center
Stanoyevitch, Alexander
2008-01-01
In this article concerning grade inflation, the author restricts his attention to the college and university level, although many of the tools and ideas developed here should be useful for high schools as well. The author considers the relationships between grades instructors assign and scores they receive on end-of-the semester student…
Lazarides, George; Vamvasakis, Achilleas
2007-10-15
We consider the extension of the supersymmetric Pati-Salam model which solves the b-quark mass problem of supersymmetric grand unified models with exact Yukawa unification and universal boundary conditions and leads to the so-called new shifted hybrid inflationary scenario. We show that this model can also lead to a new version of smooth hybrid inflation based only on renormalizable interactions provided that a particular parameter of its superpotential is somewhat small. The potential possesses valleys of minima with classical inclination, which can be used as inflationary paths. The model is consistent with the fitting of the three-year Wilkinson microwave anisotropy probe data by the standard power-law cosmological model with cold dark matter and a cosmological constant. In particular, the spectral index turns out to be adequately small so that it is compatible with the data. Moreover, the Pati-Salam gauge group is broken to the standard model gauge group during inflation and, thus, no monopoles are formed at the end of inflation. Supergravity corrections based on a nonminimal Kaehler potential with a convenient choice of a sign keep the spectral index comfortably within the allowed range without generating maxima and minima of the potential on the inflationary path. So, unnatural restrictions on the initial conditions for inflation can be avoided.
Kobayashi, Tatsuo; Nitta, Daisuke; Urakawa, Yuko
2016-08-08
Modular invariance is a striking symmetry in string theory, which may keep stringy corrections under control. In this paper, we investigate a phenomenological consequence of the modular invariance, assuming that this symmetry is preserved as well as in a four dimensional (4D) low energy effective field theory. As a concrete setup, we consider a modulus field T whose contribution in the 4D effective field theory remains invariant under the modular transformation and study inflation drived by T. The modular invariance restricts a possible form of the scalar potenntial. As a result, large field models of inflation are hardly realized. Meanwhile, a small field model of inflation can be still accomodated in this restricted setup. The scalar potential traced during the slow-roll inflation mimics the hilltop potential V{sub ht}, but it also has a non-negligible deviation from V{sub ht}. Detecting the primordial gravitational waves predicted in this model is rather challenging. Yet, we argue that it may be still possible to falsify this model by combining the information in the reheating process which can be determined self-completely in this setup.
NASA Technical Reports Server (NTRS)
Hedgepeth, J. M.
1985-01-01
Lightweight structural member easy to store. Billowing between circumferential loops of fiber inflated column becomes series of cells. Each fiber subjected to same tension along entire length (though tension is different in different fibers). Member is called "isotensoid" column. Serves as jack for automobiles or structures during repairs. Also used as support for temporary bleachers or swimming pools.
Hilltop Supernatural Inflation
NASA Astrophysics Data System (ADS)
Lin, C.
In this talk, I will explain how to reduce the spectral index to be n_s = 0.96 for supernatural inflation. I will also show the constraint to the reheating temperature from Big Bang Nucleosynthesis of both thermal and non-thermal gravitino production.
NASA Astrophysics Data System (ADS)
Kobayashi, Tatsuo; Nitta, Daisuke; Urakawa, Yuko
2016-08-01
Modular invariance is a striking symmetry in string theory, which may keep stringy corrections under control. In this paper, we investigate a phenomenological consequence of the modular invariance, assuming that this symmetry is preserved as well as in a four dimensional (4D) low energy effective field theory. As a concrete setup, we consider a modulus field T whose contribution in the 4D effective field theory remains invariant under the modular transformation and study inflation drived by T. The modular invariance restricts a possible form of the scalar potenntial. As a result, large field models of inflation are hardly realized. Meanwhile, a small field model of inflation can be still accomodated in this restricted setup. The scalar potential traced during the slow-roll inflation mimics the hilltop potential Vht, but it also has a non-negligible deviation from Vht. Detecting the primordial gravitational waves predicted in this model is rather challenging. Yet, we argue that it may be still possible to falsify this model by combining the information in the reheating process which can be determined self-completely in this setup.
Bispectrum from open inflation
NASA Astrophysics Data System (ADS)
Sugimura, Kazuyuki; Komatsu, Eiichiro
2013-11-01
We calculate the bispectrum of primordial curvature perturbations, ζ, generated during ``open inflation.'' Inflation occurs inside a bubble nucleated via quantum tunneling from the background false vacuum state. Our universe lives inside the bubble, which can be described as a Friedmann-Lemaȋtre-Robertson-Walker (FLRW) universe with negative spatial curvature, undergoing slow-roll inflation. We pay special attention to the issue of an initial state for quantum fluctuations. A ``vacuum state'' defined by a positive-frequency mode in de Sitter space charted by open coordinates is different from the Euclidean vacuum (which is equivalent to the so-called ``Bunch-Davies vacuum'' defined by a positive-frequency mode in de Sitter space charted by flat coordinates). Quantum tunneling (bubble nucleation) then modifies the initial state away from the original Euclidean vacuum. While most of the previous study on modifications of the initial quantum state introduces, by hand, an initial time at which the quantum state is modified as well as the form of the modification, an effective initial time naturally emerges and the form is fixed by quantum tunneling in open inflation models. Therefore, open inflation enables a self-consistent computation of the effect of a modified initial state on the bispectrum. We find a term which goes as langleζk1ζk2ζk3ranglepropto1/k12k34 in the so-called squeezed configurations, k3 << k1 ≈ k2, in agreement with the previous study on modifications of the initial state. The bispectrum in the exact folded limit, e.g., k1 = k2+k3, is also enhanced and remains finite. However, these terms are exponentially suppressed when the wavelength of ζ is smaller than the curvature radius of the universe. The leading-order bispectrum is equal to the usual one from single-field slow-roll inflation; the terms specific for open inflation arise only in the sub-leading order when the wavelength of ζ is smaller than the curvature radius.
Bispectrum from open inflation
Sugimura, Kazuyuki; Komatsu, Eiichiro E-mail: komatsu@mpa-garching.mpg.de
2013-11-01
We calculate the bispectrum of primordial curvature perturbations, ζ, generated during ''open inflation.'' Inflation occurs inside a bubble nucleated via quantum tunneling from the background false vacuum state. Our universe lives inside the bubble, which can be described as a Friedmann-Lemaȋtre-Robertson-Walker (FLRW) universe with negative spatial curvature, undergoing slow-roll inflation. We pay special attention to the issue of an initial state for quantum fluctuations. A ''vacuum state'' defined by a positive-frequency mode in de Sitter space charted by open coordinates is different from the Euclidean vacuum (which is equivalent to the so-called ''Bunch-Davies vacuum'' defined by a positive-frequency mode in de Sitter space charted by flat coordinates). Quantum tunneling (bubble nucleation) then modifies the initial state away from the original Euclidean vacuum. While most of the previous study on modifications of the initial quantum state introduces, by hand, an initial time at which the quantum state is modified as well as the form of the modification, an effective initial time naturally emerges and the form is fixed by quantum tunneling in open inflation models. Therefore, open inflation enables a self-consistent computation of the effect of a modified initial state on the bispectrum. We find a term which goes as (ζ{sub k{sub 1}}ζ{sub k{sub 2}}ζ{sub k{sub 3}})∝1/k{sub 1}{sup 2}k{sub 3}{sup 4} in the so-called squeezed configurations, k{sub 3} << k{sub 1} ≈ k{sub 2}, in agreement with the previous study on modifications of the initial state. The bispectrum in the exact folded limit, e.g., k{sub 1} = k{sub 2}+k{sub 3}, is also enhanced and remains finite. However, these terms are exponentially suppressed when the wavelength of ζ is smaller than the curvature radius of the universe. The leading-order bispectrum is equal to the usual one from single-field slow-roll inflation; the terms specific for open inflation arise only in the sub-leading order
Constraining holographic inflation with WMAP
Easther, Richard; Flauger, Raphael; McFadden, Paul; Skenderis, Kostas E-mail: Raphael.Flauger@yale.edu E-mail: K.Skenderis@uva.nl
2011-09-01
In a class of recently proposed models, the early universe is strongly coupled and described holographically by a three-dimensional, weakly coupled, super-renormalizable quantum field theory. This scenario leads to a power spectrum of scalar perturbations that differs from the usual empirical ΛCDM form and the predictions of generic models of single field, slow roll inflation. This spectrum is characterized by two parameters: an amplitude, and a parameter g related to the coupling constant of the dual theory. We estimate these parameters, using WMAP and other astrophysical data. We compute Bayesian evidence for both the holographic model and standard ΛCDM and find that their difference is not significant, although ΛCDM provides a somewhat better fit to the data. However, it appears that Planck will permit a definitive test of this holographic scenario.
Cosmological Inflation: A Personal Perspective
NASA Technical Reports Server (NTRS)
Kazanas, Demosthenes
2007-01-01
We present a review of the sequence of events/circumstances that led to the introduction of interplay between the physics associated with phase transitions in the early universe and their effects on its dynamics of expansion with the goal of resolving the horizon problem that it has since become known as Cosmological Inflation. We then provide a brief review of the fundamentals and the solutions of a theory of gravity based on local scale invariance, known as Weyl gravity that have been elaborated by the presenter and his collaborator P. D. Mannheim. We point out that this theory provides from first principles for a characteristic universal acceleration, whose value appears to be in agreement with observations across a vast range of length scales in the universe.
The Primordial Inflation Explorer (PIXIE)
NASA Astrophysics Data System (ADS)
Kogut, Alan; Chluba, Jens; Fixsen, Dale J.; Meyer, Stephan; Spergel, David
2016-07-01
The Primordial Inflation Explorer is an Explorer-class mission to open new windows on the early universe through measurements of the polarization and absolute frequency spectrum of the cosmic microwave background. PIXIE will measure the gravitational-wave signature of primordial inflation through its distinctive imprint in linear polarization, and characterize the thermal history of the universe through precision measurements of distortions in the blackbody spectrum. PIXIE uses an innovative optical design to achieve background-limited sensitivity in 400 spectral channels spanning over 7 octaves in frequency from 30 GHz to 6 THz (1 cm to 50 micron wavelength). Multi-moded non-imaging optics feed a polarizing Fourier Transform Spectrometer to produce a set of interference fringes, proportional to the difference spectrum between orthogonal linear polarizations from the two input beams. Multiple levels of symmetry and signal modulation combine to reduce systematic errors to negligible levels. PIXIE will map the full sky in Stokes I, Q, and U parameters with angular resolution 2.6° and sensitivity 70 nK per 1° square pixel. The principal science goal is the detection and characterization of linear polarization from an inflationary epoch in the early universe, with tensor-to-scalar ratio r < 10-3 at 5 standard deviations. The PIXIE mission complements anticipated ground-based polarization measurements such as CMB- S4, providing a cosmic-variance-limited determination of the large-scale E-mode signal to measure the optical depth, constrain models of reionization, and provide a firm detection of the neutrino mass (the last unknown parameter in the Standard Model of particle physics). In addition, PIXIE will measure the absolute frequency spectrum to characterize deviations from a blackbody with sensitivity 3 orders of magnitude beyond the seminal COBE/FIRAS limits. The sky cannot be black at this level; the expected results will constrain physical processes ranging from
Probing inflation with the cosmic microwave background
NASA Astrophysics Data System (ADS)
Braganca, Vinicius Miranda
The existence of a quasi-deSitter expansion in the early universe, known as inflation, generates the seeds of large-scale structures and is one of the foundations of the standard cosmological model. The main observational predictions from inflation include the existence of a nearly scale-invariant primordial power spectrum that is imprinted on the cosmic microwave background (CMB), which has been corroborated with remarkable precision in recent years. In single-field slow-roll inflation, a field called the inflaton dominates the energy density of the universe and slowly rolls in an almost perfectly flat potential. In addition, the motion of the inflaton field is friction dominated, with its velocity being completely specified by its position in the field space. This basic scenario is known as the slow-roll approximation and its validity is controlled by the magnitude of the so-called slow-roll parameters. Generalizations of single-field slow-roll inflation provide a wealth of observational signatures in the CMB temperature power spectrum, CMB polarization spectrum, primordial non-Guassianity and in lensing reconstruction. This thesis provides a series of consistency checks between these observables that can distinguish slow-roll violations from alternative explanations.
Inflation Fossils in Cosmic Structure
NASA Astrophysics Data System (ADS)
Kamionkowski, Marc
The agreement of the predictions of inflation with increasingly precise cosmic microwave background (CMB) and large-scale-structure (LSS) data is remarkable. The notion that such a simple early-Universe scenario, based on still-mysterious ultra-high-energy physics, can explain such a wealth of precise data is simply amazing. An active ongoing program of research is afoot to seek the CMB polarization signatures of inflationary gravitational waves and measure the primordial bispectrum in order to learn about inflation. Still, there is far more that can be done to probe inflationary physics, and no stone should be left unturned in this quest. Here we propose a multi-component program of theoretical research that includes model building, new CMB/LSS tests, a potentially powerful new survey strategy, and the investigation of a new observational avenue for large-scale structure. We propose to broaden the circle of ideas to empirically probe inflation. To begin, the hemispherical power asymmetry seen in WMAP and Planck is truly striking. While it may simply be an unusual statistical fluke, a more tantalizing possibility is that it is a remnant of the pre-inflationary Universe. We propose to develop and study several physical models for this asymmetry and work out other testable predictions of these models. Only by pursuing other signatures of whatever new physics may be responsible for this asymmetry will we be able to infer if it is truly a window to new physics. We also plan to develop departures from statistical isotropy (SI) as a test of inflationary models. We have recently shown that single-field slow-roll inflation generically predicts a quadrupolar departure from SI in primordial perturbations, albeit a very small one. The power quadrupole is expected, however, to be significantly larger in more general inflationary models. We propose to calculate these power quadrupoles so that new constraints to the power quadrupole from CMB and LSS data can be applied to test
Evading the Lyth bound in hybrid natural inflation
NASA Astrophysics Data System (ADS)
Hebecker, A.; Kraus, S. C.; Westphal, A.
2013-12-01
Generically, the gravitational-wave or tensor-mode contribution to the primordial curvature spectrum of inflation is tiny if the field range of the inflaton is much smaller than the Planck scale. We show that this pessimistic conclusion is naturally avoided in a rather broad class of small-field models. More specifically, we consider models where an axionlike shift symmetry keeps the inflaton potential flat (up to nonperturbative cosine-shaped modulations), but inflation nevertheless ends in a waterfall regime, as is typical for hybrid inflation. In such hybrid natural inflation scenarios (examples are provided by Wilson line inflation and fluxbrane inflation), the slow-roll parameter ɛ can be sizable during an early period (relevant for the cosmic microwave background spectrum). Subsequently, ɛ quickly becomes very small before the tachyonic instability eventually terminates the slow-roll regime. In this scenario, one naturally generates a considerable tensor-mode contribution in the curvature spectrum, collecting nevertheless the required amount of e-foldings during the final period of inflation. While nonobservation of tensors by Planck is certainly not a problem, a discovery in the medium- to long-term future is realistic.
NASA Astrophysics Data System (ADS)
Bachlechner, Thomas C.
2016-12-01
We argue that moduli stabilization generically restricts the evolution following transitions between weakly coupled de Sitter vacua and can induce a strong selection bias towards inflationary cosmologies. The energy density of domain walls between vacua typically destabilizes Kähler moduli and triggers a runaway towards large volume. This decompactification phase can collapse the new de Sitter region unless a minimum amount of inflation occurs after the transition. A stable vacuum transition is guaranteed only if the inflationary expansion generates overlapping past light cones for all observable modes originating from the reheating surface, which leads to an approximately flat and isotropic universe. High scale inflation is vastly favored. Our results point towards a framework for studying parameter fine-tuning and inflationary initial conditions in flux compactifications.
Erdmenger, Johanna; Halter, Sebastian; Núñez, Carlos; Tasinato, Gianmassimo E-mail: s.halter@physik.uni-muenchen.de E-mail: gianmassimo.tasinato@port.ac.uk
2013-01-01
We propose a new model of slow-roll inflation in string cosmology, based on warped throat supergravity solutions displaying 'walking' dynamics, i.e. the coupling constant of the dual gauge theory slowly varies over a range of energy scales. The features of the throat geometry are sourced by a rich field content, given by the dilaton and RR and NS fluxes. By considering the motion of a D3-brane probe in this geometry, we are able to analytically calculate the brane potential in a physically interesting regime. This potential has an inflection point: in its proximity we realize a model of inflation lasting sixty e-foldings, and whose robust predictions are in agreement with current observations. We are also able to interpret some of the most interesting aspects of this scenario in terms of the properties of the QFT dual theory.
Supersymmetric Hybrid Inflation Redux
NASA Astrophysics Data System (ADS)
Rehman, Mansoor Ur; Shafi, Qaisar; Wickman, Joshua R.
2010-02-01
We discuss the important role played during inflation by one of the soft supersymmetry breaking terms in the inflationary potential of supersymmetric hybrid inflation models. With minimal Kahler potential, the inclusion of this term allows the prediction for the scalar spectral index to agree with the value ns = 0.963^+0.014 -0.015 found by WMAP5. In the absence of this soft term, and by taking into account only radiative and supergravity corrections, it is well known that ns >= 0.985. This same soft term has previously been shown to play a key role in resolving the MSSM μ problem. The tensor to scalar ratio r is quite small in these models, taking on values r <= 10-5 in the WMAP5 2σ range of ns. )
NASA Astrophysics Data System (ADS)
Ross, Graham G.; Germán, Gabriel; Vázquez, J. Alberto
2016-05-01
We construct two simple effective field theory versions of Hybrid Natural Inflation (HNI) that illustrate the range of its phenomenological implications. The resulting inflationary sector potential, V = Δ4(1 + acos( ϕ/f)), arises naturally, with the inflaton field a pseudo-Nambu-Goldstone boson. The end of inflation is triggered by a waterfall field and the conditions for this to happen are determined. Also of interest is the fact that the slow-roll parameter ɛ (and hence the tensor r) is a non-monotonic function of the field with a maximum where observables take universal values that determines the maximum possible tensor to scalar ratio r. In one of the models the inflationary scale can be as low as the electroweak scale. We explore in detail the associated HNI phenomenology, taking account of the constraints from Black Hole production, and perform a detailed fit to the Planck 2015 temperature and polarisation data.
NASA Technical Reports Server (NTRS)
Pelt, Jennifer Van
2005-01-01
Aeroponics Internationals (AI) innovation is a self-contained, self-supporting, flexible low mass aeroponic crop production unit with integral environmental systems for the control and delivery of a nutrient mist to the roots. This FLEX Aeroponic System model was developed for commercialization as a result of the NASA SBIR Phase I contract for the research and development of a low-mass, Inflatable Aeroponic System (IAS) for producing pesticide-free lettuces, grains, peppers, tomatoes and other vegetables. The innovation addresses the needs of water and nutrient delivery systems technologies for food production in space. The inflatable nature of the innovation makes it lightweight, allowing it to be deflated so it takes up less volume during transportation and storage. It improves upon AI's current aeroponic system design that uses more rigid structures and takes advantage of vertical inclines to increase bio-mass production by over 600%.
NASA Astrophysics Data System (ADS)
Yonekura, Kazuya
2014-10-01
In the so-called natural inflation, an axion-like inflaton is assumed to have a cosine-type periodic potential. This is not the case in a very simple model in which the axion-like inflaton is coupled to an SU(N) (or other) pure Yang-Mills, at least in the large N limit as pointed out by Witten. It has a multi-valued potential, which is effectively quadratic, i.e., there is only a mass term in the large N limit. Thanks to this property, chaotic inflation can be realized more naturally with the decay constant of the axion-like inflaton less than the Planck scale. We demonstrate these points explicitly by using softly broken Script N=1 Super-Yang-Mills which allows us to treat finite N. This analysis also suggests that moderately large gauge groups such as E8 are good enough with a Planck scale decay constant.
Turner, M.S.
1987-05-01
The hot big bang cosmology, or the standard cosmology as it is appropriately known, is a highly successful model, providing a reliable and tested accounting of the Universe from 0.01 sec after the bang until today, some 15 Gyr later. However, very special initial data seem to be required in order to account for the observed smoothness and flatness of our Hubble volume and for the existence of the small primeval density inhomogeneities required for the formation of structure in the Universe. Inflation offers a means of accounting for these special initial data, which is based upon physics at sub-planck energy scales (<< m/sub pl/ approx. = 10/sup 19/ GeV) and is motivated by contemporary ideas in particle theory. Here I review the status of the 'Inflationary Paradigm'. At present essentially all inflationary models involve a very weakly-coupled (quantified by the presence of a dimensionless parameter of order 10/sup -12/ or so) scalar field which is displaced from the minimum of its potential. Regions of the Universe where the scalar field is initially displaced from its minimum undergo inflation as the scalar field relaxes, resulting in a Universe today which resembles ours in regions much larger than our present Hubble volume (approx. = 10/sup 28/ cm), but which on very large scales (>> 10/sup 28/ cm) may be highly irregular. The most conspicuous blemish on the paradigm is the lack of a compelling particle physics model to implement it. I also review some other unresolved issues, and discuss in detail the all important confrontation between inflation and observational data. Finally, I discuss the possibility that inflation leads to large-scale, primeval magnetic fields of sufficient strength to be of astrophysical interest. 123 refs., 4 figs.
Inflation from Intersecting Branes
Leblond, Louis
2007-11-20
We propose a new scenario for D-term inflation which appears quite straightforwardly in the open string sector of intersecting brane models. We take the inflaton to be a chiral field in a bifundamental representation of the hidden sector and we argue that a sufficiently flat potential can be brane engineered. This type of model generically predicts a near gaussian red spectrum with negligible tensor modes.
Turok, N.
1987-11-01
It is argued that, in fundamental string theories, as one traces the universe back in time a point is reached when the expansion rate is so fast that the rate of string creation due to quantum effects balances the dilution of the string density due to the expansion. One is therefore led into a phase of constant string density and an exponentially expanding universe. Fundamental strings therefore seem to lead naturally to inflation. 17 refs., 1 fig.
Inhomogeneous imperfect fluid inflation
NASA Astrophysics Data System (ADS)
Elizalde, E.; Silva, Luis G. T.
2017-01-01
A generalized equation of state corresponding to a model that includes a Chaplygin gas and a viscous term is investigated, in the context of the reconstruction program in scalar field cosmology. The corresponding inflationary model parameters can be conveniently adjusted in order to reproduce the most recent PLANCK data. The influence of the Chaplygin gas term contribution, in relation with previous models, is discussed. Exit from inflation is shown to occur quite naturally in the new model.
NASA Technical Reports Server (NTRS)
Turok, Neil
1988-01-01
It is argued that, in fundamental string theories, as one traces the universe back in time a point is reached when the expansion rate is so fast that the rate of string creation due to quantum effects balances the dilution of the string density due to the expansion. One is therefore led into a phase of constant string density and an exponentially expanding universe. Fundamental strings therefore seem to lead naturally to inflation.
Cosmological perturbations without inflation
NASA Astrophysics Data System (ADS)
Melia, Fulvio
2017-01-01
A particularly attractive feature of inflation is that quantum fluctuations in the inflaton field may have seeded inhomogeneities in the cosmic microwave background (CMB) and the formation of large-scale structure. In this paper, we demonstrate that a scalar field with zero active mass, i.e. with an equation of state ρ +3p=0 , where ρ and p are its energy density and pressure, respectively, could also have produced an essentially scale-free fluctuation spectrum, though without inflation. This alternative mechanism is based on the Hollands–Wald concept of a minimum wavelength for the emergence of quantum fluctuations into the semi-classical universe. A cosmology with zero active mass does not have a horizon problem, so it does not need inflation to solve this particular (non) issue. In this picture, the {{1}\\circ}{ {--}}{{10}\\circ} fluctuations in the CMB correspond almost exactly to the Planck length at the Planck time, firmly supporting the view that CMB observations may already be probing trans-Planckian physics.
PIPER: Primordial Inflation Polarization Explorer
NASA Astrophysics Data System (ADS)
Lazear, Justin; Ade, P.; Benford, D. J.; Bennett, C. L.; Chuss, D. T.; Dotson, J. L.; Eimer, J.; Fixsen, D. J.; Halpern, M.; Hinderks, J.; Hinshaw, G. F.; Irwin, K.; Jhabvala, C.; Johnson, B.; Kogut, A. J.; Mirel, P.; Moseley, S. H.; Staguhn, J.; Switzer, E.; Tucker, C. E.; Weston, A.; Wollack, E.
2014-01-01
The Primordial Inflation Polarization ExploreR (PIPER) is a balloon-borne cosmic microwave background (CMB) polarization experiment searching for large-angular scale B-mode polarization to constrain Inflation in the early universe. The Inflationary Big Bang theory predicts that the epoch of inflation will result in a background of gravitational waves. These gravitational waves imprinted their unique B-mode signature on the CMB polarization, two features of which are a peak at ell ~ 80 and a "bump" below ell ~ 10 in the B-mode angular power spectrum. The ell ~ 80 "recombination" peak is the first peak caused by gravitational waves imprinting tensor (B-mode) perturbations onto the CMB spectrum during recombination. Gravitational waves at larger scales have not yet entered the horizon and may not contribute, and at smaller scales have decayed away by other interactions, giving rise to a peak at horizon scale. The ell ~ 10 "reionization" bump is caused by a similar mechanism as the recombination peak, where gravitational waves imprint B-mode perturbations into the spectrum, now at larger horizon scales. PIPER will target the reionization bump while keeping enough angular resolution to measure the recombination peak, with sensitivity down to tensor-to-scalar ratio r = 0.007. A series of flights alternating between north and south will produce nearly full-sky temperature and polarization maps and measure the low-ell spectra. 5120 transition edge sensor (TES) bolometers each with 20 arcmin beamwidth, distributed into 4 rectangular close-packed arrays maintained at 150 mK will provide small-scale resolution and sensitivity. PIPER consists of two co-aligned telescopes, each with a front-end variable-delay polarization modulator rapidly modulating either the Q or U Stokes parameters to provide polarization sensitivity and mitigate systematic errors. To achieve background-limited sensitivity, the entire instrument is enclosed in an open bucket dewar maintained at 1.5 K. PIPER
Inflatable Structures Technology Handbook. Chapter 21; Inflatable Habitats
NASA Technical Reports Server (NTRS)
Kennedy, Kriss J.; Raboin, Jasen; Spexarth, Gary; Valle, Gerard
2000-01-01
The technologies required to design, fabricate, and utilize an inflatable module for space applications has been demonstrated and proven by the TransHab team during the development phase of the program. Through testing and hands-on development several issues about inflatable space structures have been addressed , such as: ease of manufacturing, structural integrity, micrometeorite protection, folding , and vacuum deployment. The TransHab inflatable technology development program has proven that not only are inflatable structures a viable option, but they also offer significant advantages over conventional metallic structures.
Inflatable Launch and Recovery System
2014-07-31
and air line connections. Inflatable arch shaped tubes and spacer fabric form the ramp structure from which the tow body can be launched and...also includes power electronics and software controllers. [0015] Multiple, inflatable, arch shaped tubes and spacer fabric form the ramp structure...this manner maintain their shapes when inflated. The panel 36 can be fabricated of woven spacer fabrics, also known as drop stitch fabrics. Such
Inflation driven by unification energy
NASA Astrophysics Data System (ADS)
Hertzberg, Mark P.; Wilczek, Frank
2017-03-01
We examine the hypothesis that inflation is primarily driven by vacuum energy at a scale indicated by gauge coupling unification. Concretely, we consider a class of hybrid inflation models wherein the vacuum energy associated with a grand unified theory condensate provides the dominant energy during inflation, while a second "inflaton" scalar slow rolls. We show that it is possible to obtain significant tensor-to-scalar ratios while fitting the observed spectral index.
Inflation and the Higgs Scalar
Green, Dan
2014-12-05
This note makes a self-contained exposition of the basic facts of big bang cosmology as they relate to inflation. The fundamental problems with that model are then explored. A simple scalar model of inflation is evaluated which provides the solution of those problems and makes predictions which will soon be definitively tested. The possibility that the recently discovered fundamental Higgs scalar field drives inflation is explored.
46 CFR 131.865 - Inflatable liferafts and inflatable buoyant apparatus.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 46 Shipping 4 2010-10-01 2010-10-01 false Inflatable liferafts and inflatable buoyant apparatus... SUPPLY VESSELS OPERATIONS Markings for Fire Equipment and Emergency Equipment § 131.865 Inflatable liferafts and inflatable buoyant apparatus. The number of the inflatable liferaft or inflatable...
46 CFR 131.865 - Inflatable liferafts and inflatable buoyant apparatus.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 46 Shipping 4 2011-10-01 2011-10-01 false Inflatable liferafts and inflatable buoyant apparatus... SUPPLY VESSELS OPERATIONS Markings for Fire Equipment and Emergency Equipment § 131.865 Inflatable liferafts and inflatable buoyant apparatus. The number of the inflatable liferaft or inflatable...
Inflatable robotics for planetary applications
NASA Technical Reports Server (NTRS)
Jones, Jack A.
2001-01-01
Space Inflatable vehicles have been finding popularity in recent years for applications as varied as spacecraft antennas, space-based telescopes, solar sails, and manned habitats [1]. Another branch of space inflatable technology has also considered developing ambient gasfilled, solar balloons for Mars as well as ambient gasfilled inflatable rovers [2]. More recently, some other intriguing space-inflatable vehicles have been proposed for the gas planets and Pluto, as well as for Saturn's moon, Titan, Neptune's moon, Triton, and Jupiter's moon, Io [3].
Tachyacoustic cosmology: An alternative to inflation
Bessada, Dennis; Kinney, William H.; Stojkovic, Dejan; Wang, John
2010-02-15
We consider an alternative to inflation for the generation of superhorizon perturbations in the Universe in which the speed of sound is faster than the speed of light. We label such cosmologies, first proposed by Armendariz-Picon, tachyacoustic, and explicitly construct examples of noncanonical Lagrangians which have superluminal sound speed, but which are causally self-consistent. Such models possess two horizons, a Hubble horizon and an acoustic horizon, which have independent dynamics. Even in a decelerating (noninflationary) background, a nearly scale-invariant spectrum of perturbations can be generated by quantum perturbations redshifted outside of a shrinking acoustic horizon. The acoustic horizon can be large or even infinite at early times, solving the cosmological horizon problem without inflation. These models do not, however, dynamically solve the cosmological flatness problem, which must be imposed as a boundary condition. Gravitational wave modes, which are produced by quantum fluctuations exiting the Hubble horizon, are not produced.
Ghost inflation and de Sitter entropy
Jazayeri, Sadra; Mukohyama, Shinji; Saitou, Rio; Watanabe, Yota
2016-08-01
In the setup of ghost condensation model the generalized second law of black hole thermodynamics can be respected under a radiatively stable assumption that couplings between the field responsible for ghost condensate and matter fields such as those in the Standard Model are suppressed by the Planck scale. Since not only black holes but also cosmology are expected to play important roles towards our better understanding of gravity, we consider a cosmological setup to test the theory of ghost condensation. In particular we shall show that the de Sitter entropy bound proposed by Arkani-Hamed, et al. is satisfied if ghost inflation happened in the early epoch of our universe and if there remains a tiny positive cosmological constant in the future infinity. We then propose a notion of cosmological Page time after inflation.
Inflation Accounting Methods and their Effectiveness.
accounting and current cost accounting are explained as the major inflation accounting methods. Inflation accounting standards announced in the United...inflation accounting, constant purchasing power accounting, constant dollar accounting, current cost accounting , current value.
Predictions From Eternal Inflation
NASA Astrophysics Data System (ADS)
Leichenauer, Stefan
We investigate the physics of eternal inflation, particularly the use of multiverse ideas to explain the observed values of the cosmological constant and the coincidences of cosmological timescales. We begin by reviewing eternal inflation, the multiverse, and the resulting measure problem. Then follows a detailed study of proposals to solve the measure problem, both analytical and numerical, including an analysis of their predictions for cosmological observables. A key outcome of this investigation is that the traditional anthropic calculations, which take into account the necessity of galaxies and heavy elements to produce observers, are redundant in our framework. The cosmological coincidence problem, the seemingly coincidental equality of the timescales of observation and of vacuum domination, is solved for the first time without appeal to detailed anthropic assumptions: very general geometric considerations do the job automatically. We also estimate a 10% likelihood that evidence for eternal inflation will be found in upcoming measurements of the energy density of the universe. Encouraged by this success, we go on to construct a modified version of the light-cone time measure which has conceptual advantages but also reproduces the phenomenology of its predecessor. We complete our study of the measure problem by noting that for a wide class of proposed solutions, including the one developed here, there is an implicit assumption being made about a catastrophic end to the universe. Finally, as a by-product of this research program we find geometries which violate some of the accepted common knowledge on holographic entropy bounds. We point this out and conjecture a general result.
Attachment device for an inflatable protective cushion
Nelsen, James M.; Luna, Daniel A.; Gwinn, Kenneth W.
1997-01-01
An inflatable cushion assembly for use with an inflator comprises an inflatable cushion having an inner surface, outer surface, and at least one protrusion extending from one of the inner or outer surfaces. The inflatable cushion defines an opening between the inner surface and the outer surface for receiving the inflator. An attachment member contacts the one of the inner or outer surfaces adjacent the opening and includes a groove for receiving the protrusion, the attachment member securing the inflator within the opening.
Attachment device for an inflatable protective cushion
Nelsen, James M.; Luna, Daniel A.; Gwinn, Kenneth W.
1998-01-01
An inflatable cushion assembly for use with an inflator comprises an inflatable cushion having an inner surface, outer surface, and at least one protrusion extending from one of the inner or outer surfaces. The inflatable cushion defines an opening between the inner surface and the outer surface for receiving the inflator. An attachment member contacts the one of the inner or outer surfaces adjacent the opening and includes a groove for receiving the protrusion, the attachment member securing the inflator within the opening.
Low-Mass Inflation Systems for Inflatable Structures
NASA Technical Reports Server (NTRS)
Thunnissen, Daniel P.; Webster, Mark S.; Engelbrecht, Carl S.
1995-01-01
The use of inflatable space structures has often been proposed for aerospace and planetary applications. Communication, power generation, and very-long-baseline interferometry are just three potential applications of inflatable technology. The success of inflatable structures depends on the development of an applications of inflatable technology. This paper describes two design studies performed to develop a low mass inflation system. The first study takes advantage of existing onboard propulsion gases to reduce the overall system mass. The second study assumes that there is no onboard propulsion system. Both studies employ advanced components developed for the Pluto fast flyby spacecraft to further reduce mass. The study examined four different types of systems: hydrazine, nitrogen and water, nitrogen, and xenon. This study shows that all of these systems can be built for a small space structure with masses lower than 0.5 kilograms.
Quantum gravity slows inflation
Tsamis, N.C. |; Woodard, R.P.
1996-02-01
We consider the quantum gravitational back-reaction on an initially inflating, homogeneous and isotropic universe whose topology is T{sup 3} {times} {Re}. Although there is no secular effect at one loop, an explicit calculation shows that two-loop processes act to slow the rate of expansion by an amount which becomes non-pertubatively large at late times. By exploiting Feynman`s tree theorem we show that all higher loops act in the same sense. 18 refs., 1 fig.
Triple unification of inflation, dark matter, and dark energy using a single field
Liddle, Andrew R.; Pahud, Cedric; Urena-Lopez, L. Arturo
2008-06-15
We construct an explicit scenario whereby the same material driving inflation in the early universe can comprise dark matter in the present universe, using a simple quadratic potential. Following inflation and preheating, the density of inflaton/dark matter particles is reduced to the observed level by a period of thermal inflation, of a duration already invoked in the literature for other reasons. Within the context of the string landscape, one can further argue for a nonzero vacuum energy of this field, thus unifying inflation, dark matter, and dark energy into a single fundamental field.
Therapeutic Play at Inflatable Playgrounds
ERIC Educational Resources Information Center
Yavorcik, Carin
2009-01-01
The environment at indoor inflatable playgrounds, featuring giant bounce houses and slides, can become an ideal place for children with autism to receive helpful sensations. This is the reasoning behind Sensory Nights hosted by the Autism Society of America and Pump It Up, a national franchise of giant, indoor inflatable playgrounds. The private…
A Methane Balloon Inflation Chamber
ERIC Educational Resources Information Center
Czerwinski, Curtis J.; Cordes, Tanya J.; Franek, Joe
2005-01-01
The various equipments, procedure and hazards in constructing the device for inflating a methane balloon using a standard methane outlet in a laboratory are described. This device is fast, safe, inexpensive, and easy to use as compared to a hydrogen gas cylinder for inflating balloons.
Testing inflation: a bootstrap approach.
Boyle, Latham; Steinhardt, Paul J
2010-12-10
We note that the essential idea of inflation, that the Universe underwent a brief period of accelerated expansion followed by a long period of decelerated expansion, can be encapsulated in a "closure condition" which relates the amount of accelerated expansion during inflation to the amount of decelerated expansion afterward. We present a protocol for systematically testing the validity of this condition observationally.
Topological inflation with graceful exit
NASA Astrophysics Data System (ADS)
Marunović, Anja; Prokopec, Tomislav
2016-04-01
We investigate a class of models of topological inflation in which a super-Hubble-sized global monopole seeds inflation. These models are attractive since inflation starts from rather generic initial conditions, but their not so attractive feature is that, unless symmetry is again restored, inflation never ends. In this work we show that, in presence of another nonminimally coupled scalar field, that is both quadratically and quartically coupled to the Ricci scalar, inflation naturally ends, representing an elegant solution to the graceful exit problem of topological inflation. While the monopole core grows during inflation, the growth stops after inflation, such that the monopole eventually enters the Hubble radius, and shrinks to its Minkowski space size, rendering it immaterial for the subsequent Universe's dynamics. Furthermore, we find that our model can produce cosmological perturbations that source CMB temperature fluctuations and seed large scale structure statistically consistent (within one standard deviation) with all available data. In particular, for small and (in our convention) negative nonminimal couplings, the scalar spectral index can be as large as ns simeq 0.955, which is about one standard deviation lower than the central value quoted by the most recent Planck Collaboration.
Inflation and the Retired Professor.
ERIC Educational Resources Information Center
Corson, Dale R.
1979-01-01
Problems faced by a TIAA-CREF annuitant retiring in the late 1970s are examined in light of a continuing high rate of inflation. Options available to the annuitant are discussed and two strategies to provide significant inflation protection are suggested. (SF)
Inflatable stretcher to transport patients
NASA Technical Reports Server (NTRS)
Clark, C. C.; Gordon, F. T., Jr.; Schmidt, C. B.
1970-01-01
Inflatable plastic bag inside strong, inflexible outer bag facilitates emergency transport of seriously burned or disabled patients. When the bag is inflated the patient is completely immobilized and cushioned from external shock. Air for breathing, temperature controls and communications may be provided by appropriate plug-in connections.
Cicoli, Michele; Pedro, Francisco G.; Tasinato, Gianmassimo E-mail: f.pedro1@physics.ox.ac.uk
2011-12-01
We propose a new inflationary scenario in type IIB Calabi-Yau compactifications, where the inflaton is a Kähler modulus parameterising the volume of an internal four-cycle. The inflaton potential is generated via poly-instanton corrections to the superpotential which give rise to a naturally flat direction due to their double exponential suppression. Given that the volume mode is kept stable during inflation, all the inflaton-dependent higher dimensional operators are suppressed. Moreover, string loop effects can be shown to be negligible throughout all the inflationary dynamics for natural values of the underlying parameters. The model is characterised by a reheating temperature of the order T{sub rh} ≅ 10{sup 6} GeV which requires N{sub e} ≅ 54 e-foldings of inflation. All the inflationary observables are compatible with current observations since the spectral index is n{sub s} ≅ 0.96, while the tensor-to-scalar ratio is r ≅ 10{sup −5}. The volume of the Calabi-Yau is of order 10{sup 3} in string units, corresponding to an inflationary scale around 10{sup 15} GeV.
Inflation in supersymmetric SU(5)
Khalil, S.; Rehman, M. U.; Shafi, Q.; Zaakouk, E. A.
2011-03-15
We analyze the adjoint field inflation in supersymmetric (SUSY) SU(5) model. In minimal SUSY SU(5) hybrid inflation monopoles are produced at the end of inflation. We therefore explore the nonminimal model of inflation based on SUSY SU(5), like shifted hybrid inflation, which provides a natural solution for the monopole problem. We find that the supergravity corrections with nonminimal Kaehler potential are crucial to realize the central value of the scalar spectral index n{sub s{approx_equal}}0.96 consistent with the 7 yr WMAP data. The tensor to scalar ratio r is quite small, taking on values r < or approx. 10{sup -5}. Because of R symmetry massless SU(3) octet and SU(2) triplet supermultiplets are present and could spoil gauge coupling unification. To keep gauge coupling unification intact, light vectorlike particles are added which are expected to be observed at LHC.
Structurally efficient inflatable protective device
Nelsen, J.M.; Whinery, L.D.; Gwinn, K.W.; McBride, D.D.; Luna, D.A.; Holder, J.P.; Bliton, R.J.
1997-03-04
An apparatus and method are disclosed for making a low cost, self-venting, inflatable protective cushion of simple and structurally efficient design with a shape and construction that optimizes the cushion`s ability to withstand inflation pressures and impact when deployed which includes a sheet defined by at least one fold line and a plurality of flap portions, each flap portion having a base edge corresponding to a fold line and at least two side edges each extending outwardly from a base edge and ultimately converging to meet each other, the flap portions being folded at the fold line(s) and being joined at corresponding side edges to define an inflatable chamber. The inflatable protective cushion and method for making same may further include a lightweight, low permeability, fabric that optimizes the cushion`s ability to withstand inflation pressures and impact when deployed and minimizes the packed volume of the cushion when stored. 22 figs.
Structurally efficient inflatable protective device
Nelsen, J.M.; Whinery, L.D.; Gwinn, K.W.; McBride, D.D.; Luna, D.A.; Holder, J.P.; Bliton, R.J.
1996-01-09
An apparatus and method are disclosed for making a low cost, self-venting, inflatable protective cushion of simple and structurally efficient design with a shape and construction that optimizes the cushion`s ability to withstand inflation pressures and impact when deployed which includes a sheet defined by at least one fold line and a plurality of flap portions, each flap portion having a base edge corresponding to a fold line and at least two side edges each extending outwardly from a base edge and ultimately converging to meet each other, the flap portions being folded at the fold line(s) and being joined at corresponding side edges to define an inflatable chamber. The inflatable protective cushion and method for making same may further include a lightweight, low permeability, fabric that optimizes the cushion`s ability to withstand inflation pressures and impact when deployed and minimizes the packed volume of the cushion when stored. 22 figs.
Structurally efficient inflatable protective device
Nelsen, James M.; Whinery, Larry D.; Gwinn, Kenneth W.; McBride, Donald D.; Luna, Daniel A.; Holder, Joseph P.; Bliton, Richard J.
1997-01-01
An apparatus and method for making a low cost, self-venting, inflatable protective cushion of simple and structurally efficient design with a shape and construction that optimizes the cushion's ability to withstand inflation pressures and impact when deployed which includes a sheet defined by at least one fold line and a plurality of flap portions, each flap portion having a base edge corresponding to a fold line and at least two side edges each extending outwardly from a base edge and ultimately converging to meet each other, the flap portions being folded at the fold line(s) and being joined at corresponding side edges to define an inflatable chamber. The inflatable protective cushion and method for making same may further include a lightweight, low permeability, fabric that optimizes the cushion's ability to withstand inflation pressures and impact when deployed and minimizes the packed volume of the cushion when stored.
Structurally efficient inflatable protective device
Nelsen, James M.; Whinery, Larry D.; Gwinn, Kenneth W.; McBride, Donald D.; Luna, Daniel A.; Holder, Joseph P.; Bliton, Richard J.
1996-01-01
An apparatus and method for making a low cost, self-venting, inflatable protective cushion of simple and structurally efficient design with a shape and construction that optimizes the cushion's ability to withstand inflation pressures and impact when deployed which includes a sheet defined by at least one fold line and a plurality of flap portions, each flap portion having a base edge corresponding to a fold line and at least two side edges each extending outwardly from a base edge and ultimately converging to meet each other, the flap portions being folded at the fold line(s) and being Joined at corresponding side edges to define an inflatable chamber. The inflatable protective cushion and method for making same may further include a lightweight, low permeability, fabric that optimizes the cushion's ability to withstand inflation pressures and impact when deployed and minimizes the packed volume of the cushion when stored.
Structurally efficient inflatable protective device
Nelsen, James M.; Whinery, Larry D.; Gwinn, Kenneth W.; McBride, Donald D.; Luna, Daniel A.; Holder, Joseph P.; Bliton, Richard J.
1996-01-01
An apparatus and method for making a low cost, self-venting, inflatable protective cushion of simple and structurally efficient design with a shape and construction that optimizes the cushion's ability to withstand inflation pressures and impact when deployed which includes a sheet defined by at least one fold line and a plurality of flap portions, each flap portion having a base edge corresponding to a fold line and at least two side edges each extending outwardly from a base edge and ultimately converging to meet each other, the flap portions being folded at the fold line(s) and being joined at corresponding side edges to define an inflatable chamber. The inflatable protective cushion and method for making same may further include a lightweight, low permeability, fabric that optimizes the cushion's ability to withstand inflation pressures and impact when deployed and minimizes the packed volume of the cushion when stored.
Constraining inflation with future galaxy redshift surveys
Huang, Zhiqi; Vernizzi, Filippo; Verde, Licia E-mail: liciaverde@icc.ub.edu
2012-04-01
With future galaxy surveys, a huge number of Fourier modes of the distribution of the large scale structures in the Universe will become available. These modes are complementary to those of the CMB and can be used to set constraints on models of the early universe, such as inflation. Using a MCMC analysis, we compare the power of the CMB with that of the combination of CMB and galaxy survey data, to constrain the power spectrum of primordial fluctuations generated during inflation. We base our analysis on the Planck satellite and a spectroscopic redshift survey with configuration parameters close to those of the Euclid mission as examples. We first consider models of slow-roll inflation, and show that the inclusion of large scale structure data improves the constraints by nearly halving the error bars on the scalar spectral index and its running. If we attempt to reconstruct the inflationary single-field potential, a similar conclusion can be reached on the parameters characterizing the potential. We then study models with features in the power spectrum. In particular, we consider ringing features produced by a break in the potential and oscillations such as in axion monodromy. Adding large scale structures improves the constraints on features by more than a factor of two. In axion monodromy we show that there are oscillations with small amplitude and frequency in momentum space that are undetected by CMB alone but can be measured by including galaxy surveys in the analysis.
Hybrid Inflatable Pressure Vessel
NASA Technical Reports Server (NTRS)
Raboin, Jasen; Valle, Gerard D.; Edeen, Gregg; DeLaFuente, Horacio M.; Schneider, William C.; Spexarth, Gary R.; Johnson, Christopher J.; Pandya, Shalini
2004-01-01
Figure 1 shows a prototype of a large pressure vessel under development for eventual use as a habitable module for long spaceflight (e.g., for transporting humans to Mars). The vessel is a hybrid that comprises an inflatable shell attached to a rigid central structural core. The inflatable shell is, itself, a hybrid that comprises (1) a pressure bladder restrained against expansion by (2) a web of straps made from high-strength polymeric fabrics. On Earth, pressure vessels like this could be used, for example, as portable habitats that could be set up quickly in remote locations, portable hyperbaric chambers for treatment of decompression sickness, or flotation devices for offshore platforms. In addition, some aspects of the design of the fabric straps could be adapted to such other items as lifting straps, parachute straps, and automotive safety belts. Figure 2 depicts selected aspects of the design of a vessel of this type with a toroidal configuration. The bladder serves as an impermeable layer to keep air within the pressure vessel and, for this purpose, is sealed to the central structural core. The web includes longitudinal and circumferential straps. To help maintain the proper shape upon inflation after storage, longitudinal and circumferential straps are indexed together at several of their intersections. Because the web is not required to provide a pressure seal and the bladder is not required to sustain structural loads, the bladder and the web can be optimized for their respective functions. Thus, the bladder can be sealed directly to the rigid core without having to include the web in the seal substructure, and the web can be designed for strength. The ends of the longitudinal straps are attached to the ends of the rigid structural core by means of clevises. Each clevis pin is surrounded by a roller, around which a longitudinal strap is wrapped to form a lap seam with itself. The roller is of a large diameter chosen to reduce bending of the fibers in
Constraining monodromy inflation
Peiris, Hiranya V.; Easther, Richard; Flauger, Raphael E-mail: r.easther@auckland.ac.nz
2013-09-01
We use cosmic microwave background (CMB) data from the 9-year WMAP release to derive constraints on monodromy inflation, which is characterized by a linear inflaton potential with a periodic modulation. We identify two possible periodic modulations that significantly improve the fit, lowering χ{sup 2} by approximately 10 and 20. However, standard Bayesian model selection criteria assign roughly equal odds to the modulated potential and the unmodulated case. A modulated inflationary potential can generate substantial primordial non-Gaussianity with a specific and characteristic form. For the best-fit parameters to the WMAP angular power spectrum, the corresponding non-Gaussianity might be detectable in upcoming CMB data, allowing nontrivial consistency checks on the predictions of a modulated inflationary potential.
Kahler moduli inflation revisited
NASA Astrophysics Data System (ADS)
Blanco-Pillado, Jose J.; Buck, Duncan; Copeland, Edmund J.; Gomez-Reino, Marta; Nunes, Nelson J.
2010-01-01
We perform a detailed numerical analysis of inflationary solutions in Kahler moduli of type IIB flux compactifications. We show that there are inflationary solutions even when all the fields play an important role in the overall shape of the scalar potential. Moreover, there exists a direction of attraction for the inflationary trajectories that correspond to the constant volume direction. This basin of attraction enables the system to have an island of stability in the set of initial conditions. We provide explicit examples of these trajectories, compute the corresponding tilt of the density perturbations power spectrum and show that they provide a robust prediction of n s ≈ 0.96 for 60 e-folds of inflation.
Lewis, C.M. )
1991-09-15
A vector field {ital A}{sub {mu}} is coupled to the Einstein equations with a linearly perturbed Friedmann-Robertson-Walker metric, constructed to generate first-order vector perturbations. A working classical chaotic vector inflation is demonstrated and then quantum fluctuations of the field are used to constrain the cosmological perturbations. In particular, the vector momentum flux {ital T}{sub 0{ital i}} is tracked to the epoch where radiation-dominated matter exists. Matching conditions using observational constraints of the cosmic microwave background radiation give rise to a peculiar cosmological velocity of the order of 10{sup {minus}100}{ital c}. Amplification of this number, e.g., by breaking the conformal invariance of the field, could be used to generate cosmic magnetic fields using a dynamo mechanism.
Dissipative universe-inflation with soft singularity
NASA Astrophysics Data System (ADS)
Brevik, Iver; Timoshkin, Alexander V.
We investigate the early-time accelerated universe after the Big Bang. We pay attention to the dissipative properties of the inflationary universe in the presence of a soft type singularity, making use of the parameters of the generalized equation of state of the fluid. Flat Friedmann-Robertson-Walker metric is being used. We consider cosmological models leading to the so-called type IV singular inflation. Our obtained theoretical results are compared with observational data from the Planck satellite. The theoretical predictions for the spectral index turn out to be in agreement with the data, while for the scalar-to-tensor ratio, there are minor deviations.
12 CFR 19.240 - Inflation adjustments.
Code of Federal Regulations, 2010 CFR
2010-01-01
... 12 Banks and Banking 1 2010-01-01 2010-01-01 false Inflation adjustments. 19.240 Section 19.240... PROCEDURE Civil Money Penalty Inflation Adjustments § 19.240 Inflation adjustments. (a) The maximum amount... Civil Penalties Inflation Adjustment Act of 1990 (28 U.S.C. 2461 note) as follows: ER10NO08.001 (b)...
12 CFR 19.240 - Inflation adjustments.
Code of Federal Regulations, 2011 CFR
2011-01-01
... 12 Banks and Banking 1 2011-01-01 2011-01-01 false Inflation adjustments. 19.240 Section 19.240... PROCEDURE Civil Money Penalty Inflation Adjustments § 19.240 Inflation adjustments. (a) The maximum amount... Civil Penalties Inflation Adjustment Act of 1990 (28 U.S.C. 2461 note) as follows: ER10NO08.001 (b)...
Leptogenesis in smooth hybrid inflation
NASA Astrophysics Data System (ADS)
Jeannerot, R.; Khalil, S.; Lazarides, G.
2001-05-01
We present a concrete supersymmetric grand unified model based on the Pati-Salam gauge group SU(4)c×SU(2)L×SU(2)R and leading naturally to smooth hybrid inflation, which avoids the cosmological disaster encountered in the standard hybrid inflationary scenario from the overproduction of monopoles at the end of inflation. Successful `reheating' which satisfies the gravitino constraint takes place after the termination of inflation. Also, adequate baryogenesis via a primordial leptogenesis occurs consistently with the solar and atmospheric neutrino oscillation data as well as the SU(4)c symmetry.
NASA Technical Reports Server (NTRS)
1963-01-01
Aboard a truck and ready for a test flight is the Paresev 1-C on the ramp at the NASA Flight Research Center, Edwards, California. The half-scale version of the inflatable Gemini parawing was pre-flighted by being carried across the Rosamond dry lakebed on the back of a truck before a tow behind an International Harvester Carry- All. The inflatable center spar ran fore and aft and measured 191 inches, two other inflatable spars formed the leading edges. The three compartments were filled with nitrogen under pressure to make them rigid. The Paresev 1-C was very unstable in flight with this configuration.
Supernatural inflation: inflation from supersymmetry with no (very) small parameters
NASA Astrophysics Data System (ADS)
Randall, Lisa; SoljačiĆ, Marin; Guth, Alan H.
1996-02-01
Most models of inflation have small parameters, either to guarantee sufficient inflation or the correct magnitude of the density perturbations. In this paper we show that, in supersymmetric theories with weak-scale supersymmetry breaking, one can construct viable inflationary models in which the requisite parameters appear naturally in the form of the ratio of mass scales that are already present in the theory. Successful inflationary models can be constructed from the flat-direction fields of a renormalizable supersymmetric potential, and such models can be realized even in the context of a simple GUT extension of the MSSM. We evade naive ``naturalness'' arguments by allowing for more than one field to be relevant to inflation, as in ``hybrid inflation'' models, and we argue that this is the most natural possibility if inflation fields are to be associated with flat direction fields of a supersymmetric theory. Such models predict a very low Hubble constant during inflation, of order 103-104 GeV, a scalar density perturbation index n which is very close to or greater than unity, and negligible tensor perturbations. In addition, these models lead to a large spike in the density perturbation spectrum at short wavelengths.
Tachyon field in intermediate inflation
Campo, Sergio del; Herrera, Ramon; Toloza, Adolfo
2009-04-15
The tachyonic inflationary universe model in the context of intermediate inflation is studied. General conditions for this model to be realizable are discussed. In the slow-roll approximation, we describe in great detail the characteristics of this model.
Consistency of warm k -inflation
NASA Astrophysics Data System (ADS)
Peng, Zhi-Peng; Yu, Jia-Ning; Zhu, Jian-Yang; Zhang, Xiao-Min
2016-11-01
We extend k -inflation which is a type of kinetically driven inflationary model under the standard inflationary scenario to a possible warm inflationary scenario. The dynamical equations of this warm k -inflation model are obtained. We rewrite the slow-roll parameters which are different from the usual potential driven inflationary models and perform a linear stability analysis to give the proper slow-roll conditions in warm k -inflation. Two cases, a power-law kinetic function and an exponential kinetic function, are studied, when the dissipative coefficient Γ =Γ0 and Γ =Γ (ϕ ), respectively. A proper number of e-folds is obtained in both concrete cases of warm k -inflation. We find a constant dissipative coefficient (Γ =Γ0) is not a workable choice for these two cases while the two cases with Γ =Γ (ϕ ) are self-consistent warm inflationary models.
Coherent phase argument for inflation
Scott Dodelson
2004-03-17
Cosmologists have developed a phenomenally successful picture of structure in the universe based on the idea that the universe expanded exponentially in its earliest moments. There are three pieces of evidence for this exponential expansion--inflation--from observations of anisotropies in the cosmic microwave background. First, the shape of the primordial spectrum is very similar to that predicted by generic inflation models. Second, the angular scale at which the first acoustic peak appears is consistent with the flat universe predicted by inflation. Here the author describes the third piece of evidence, perhaps the most convincing of all: the phase coherence needed to account for the clear peak/trough structure observed by the WMAP satellite and its predecessors. The author also discusses alternatives to inflation that have been proposed recently and explain how they produce coherent phases.
Linear inflation from quartic potential
NASA Astrophysics Data System (ADS)
Kannike, Kristjan; Racioppi, Antonio; Raidal, Martti
2016-01-01
We show that if the inflaton has a non-minimal coupling to gravity and the Planck scale is dynamically generated, the results of Coleman-Weinberg inflation are confined in between two attractor solutions: quadratic inflation, which is ruled out by the recent measurements, and linear inflation which, instead, is in the experimental allowed region. The minimal scenario has only one free parameter — the inflaton's non-minimal coupling to gravity — that determines all physical parameters such as the tensor-to-scalar ratio and the reheating temperature of the Universe. Should the more precise future measurements of inflationary parameters point towards linear inflation, further interest in scale-invariant scenarios would be motivated.
New Millenium Inflatable Structures Technology
NASA Technical Reports Server (NTRS)
Mollerick, Ralph
1997-01-01
Specific applications where inflatable technology can enable or enhance future space missions are tabulated. The applicability of the inflatable technology to large aperture infra-red astronomy missions is discussed. Space flight validation and risk reduction are emphasized along with the importance of analytical tools in deriving structurally sound concepts and performing optimizations using compatible codes. Deployment dynamics control, fabrication techniques, and system testing are addressed.
Complex Hybrid Inflation and Baryogenesis
Delepine, David; Martinez, Carlos; Urena-Lopez, L. Arturo
2007-04-20
We propose a hybrid inflation model with a complex waterfall field which contains an interaction term that breaks the U(1) global symmetry associated with the waterfall field charge. We show that the asymmetric evolution of the real and imaginary parts of the complex field during the phase transition at the end of inflation translates into a charge asymmetry. The latter strongly depends on the vacuum expectation value of the waterfall field, which is well constrained by diverse cosmological observations.
Oil prices and world inflation
Sheehan, R.G.; Kelly, N.
1983-06-01
This paper addresses the nature of the causal relationships between oil prices and US inflation using a procedure developed by Granger to assess causality or, more precisely stated, informativeness. The results confirm that higher oil prices have increased the US wholesale price index (WPI). The results also support OPEC's contention that their price increases have, in part, been a result of worldwide inflation. 9 references, 2 tables.
NASA Astrophysics Data System (ADS)
Notari, Alessio; Tywoniuk, Konrad
2016-12-01
We analyze in detail the background cosmological evolution of a scalar field coupled to a massless abelian gauge field through an axial term phi/fγ F ~F, such as in the case of an axion. Gauge fields in this case are known to experience tachyonic growth and therefore can backreact on the background as an effective dissipation into radiation energy density ρR, which can lead to inflation without the need of a flat potential. We analyze the system, for momenta k smaller than the cutoff fγ, including the backreaction numerically. We consider the evolution from a given static initial condition and explicitly show that, if fγ is smaller than the field excursion phi0 by about a factor of at least Script O (20), there is a friction effect which turns on before the field can fall down and which can then lead to a very long stage of inflation with a generic potential. In addition we find superimposed oscillations, which would get imprinted on any kind of perturbations, scalars and tensors. Such oscillations have a period of 4-5 efolds and an amplitude which is typically less than a few percent and decreases linearly with fγ. We also stress that the curvature perturbation on uniform density slices should be sensitive to slow-roll parameters related to ρR rather than dot phi2/2 and we discuss the existence of friction terms acting on the perturbations, although we postpone a calculation of the power spectrum and of non-gaussianity to future work and we simply define and compute suitable slow roll parameters. Finally we stress that this scenario may be realized in the axion case, if the coupling 1/fγ to U(1) (photons) is much larger than the coupling 1/fG to non-abelian gauge fields (gluons), since the latter sets the range of the potential and therefore the maximal allowed phi0~ fG.
NASA Astrophysics Data System (ADS)
Hinterbichler, Kurt; Joyce, Austin; Khoury, Justin
2017-01-01
We investigate the symmetry structure of inflation in 2+1 dimensions. In particular, we show that the asymptotic symmetries of three-dimensional de Sitter space are in one-to-one correspondence with cosmological adiabatic modes for the curvature perturbation. In 2+1 dimensions, the asymptotic symmetry algebra is infinite-dimensional, given by two copies of the Virasoro algebra, and can be traced to the conformal symmetries of the two-dimensional spatial slices of de Sitter. We study the consequences of this infinite-dimensional symmetry for inflationary correlation functions, finding new soft theorems that hold only in 2+1 dimensions. Expanding the correlation functions as a power series in the soft momentum q, these relations constrain the traceless part of the tensorial coefficient at each order in q in terms of a lower-point function. As a check, we verify that the Script O(q2) identity is satisfied by inflationary correlation functions in the limit of small sound speed.
Aguirre, Anthony; Johnson, Matthew C.
2006-06-15
We investigate the formation via tunneling of inflating (false-vacuum) bubbles in a true-vacuum background, and the reverse process. Using effective potentials from the junction condition formalism, all true- and false-vacuum bubble solutions with positive interior and exterior cosmological constant, and arbitrary mass are catalogued. We find that tunneling through the same effective potential appears to describe two distinct processes: one in which the initial and final states are separated by a wormhole (the Farhi-Guth-Guven mechanism), and one in which they are either in the same hubble volume or separated by a cosmological horizon. In the zero-mass limit, the first process corresponds to the creation of an inhomogenous universe from nothing, while the second mechanism is equivalent to the nucleation of true- or false-vacuum Coleman-De Luccia bubbles. We compute the probabilities of both mechanisms in the WKB approximation using semiclassical Hamiltonian methods, and find that--assuming both process are allowed--neither mechanism dominates in all regimes.
Higgs Inflation in f(Φ, r) Theory
NASA Astrophysics Data System (ADS)
Chakravarty, Girish Kumar; Mohanty, Subhendra; Singh, Naveen K.
2014-02-01
We generalize the scalar-curvature coupling model ξΦ2R of Higgs inflation to ξΦaRb to study inflation. We compute the amplitude and spectral index of curvature perturbations generated during inflation and fix the parameters of the model by comparing these with the Planck + WP data. We find that if the scalar self-coupling λ is in the range 10-5-0.1, parameter a in the range 2.3-3.6 and b in the range 0.77-0.22 at the Planck scale, one can have a viable inflation model even for ξ ≃ 1. The tensor to scalar ratio r in this model is small and our model with scalar-curvature couplings is not ruled out by observational limits on r unlike the pure (λ )/(4) Φ 4 theory. By requiring the curvature coupling parameter to be of order unity, we have evaded the problem of unitarity violation in scalar-graviton scatterings which plague the ξΦ2R Higgs inflation models. We conclude that the Higgs field may still be a good candidate for being the inflaton in the early universe if one considers higher-dimensional curvature coupling.
How thermal inflation can save minimal hybrid inflation in supergravity
Dimopoulos, Konstantinos; Owen, Charlotte
2016-10-12
Minimal hybrid inflation in supergravity has been ruled out by the 2015 Planck observations because the spectral index of the produced curvature perturbation falls outside observational bounds. To resurrect the model, a number of modifications have been put forward but many of them spoil the accidental cancellation that resolves the η-problem and require complicated Kähler constructions to counterbalance the lost cancellation. In contrast, in this paper the model is rendered viable by supplementing the scenario with a brief period of thermal inflation, which follows the reheating of primordial inflation. The scalar field responsible for thermal inflation requires a large non-zero vacuum expectation value (VEV) and a flat potential. We investigate the VEV of such a flaton field and its subsequent effect on the inflationary observables. We find that, for large VEV, minimal hybrid inflation in supergravity produces a spectral index within the 1-σ Planck bound and a tensor-to-scalar ratio which may be observable in the near future. The mechanism is applicable to other inflationary models.
Attachment device for an inflatable protective cushion
Nelsen, J.M.; Luna, D.A.; Gwinn, K.W.
1998-12-08
An inflatable cushion assembly for use with an inflator comprises an inflatable cushion having an inner surface, outer surface, and at least one protrusion extending from one of the inner or outer surfaces. The inflatable cushion defines an opening between the inner surface and the outer surface for receiving the inflator. An attachment member contacts the one of the inner or outer surfaces adjacent the opening and includes a groove for receiving the protrusion, the attachment member securing the inflator within the opening. 22 figs.
Attachment device for an inflatable protective cushion
Nelsen, J.M.; Luna, D.A.; Gwinn, K.W.
1997-11-18
An inflatable cushion assembly for use with an inflator comprises an inflatable cushion having an inner surface, outer surface, and at least one protrusion extending from one of the inner or outer surfaces. The inflatable cushion defines an opening between the inner surface and the outer surface for receiving the inflator. An attachment member contacts the one of the inner or outer surfaces adjacent the opening and includes a groove for receiving the protrusion, the attachment member securing the inflator within the opening. 22 figs.
NASA Astrophysics Data System (ADS)
McDonald, John
2016-08-01
Inflation due to a nonminimally coupled scalar field, as first proposed by Salopek, Bardeen and Bond (SBB), is in good agreement with the observed value of the spectral index and constraints on the tensor-to-scalar ratio. Here we explore the possibility that SBB inflation represents the late stage of a Universe which emerges from an early contracting era. We present a model in which the Universe smoothly transitions from an anamorphic contracting era to late-time SBB inflation without encountering a singular bounce. This corresponds to a continuous expansion in the Einstein frame throughout. We show that the anamorphic contracting era is able to provide the smooth superhorizon initial conditions necessary for subsequent SBB inflation to occur. The model predicts corrections to the nonminimal coupling, kinetic term and potential of SBB inflation which can observably increase the spectral index relative to its SBB prediction.
Concentric Nested Toroidal Inflatable Structures
NASA Technical Reports Server (NTRS)
Johnson, Christopher J.; Raboin, Jasen L.; Spexarth, Gary R.
2010-01-01
Assemblies comprising multiple limited- height toroidal inflatable structures nested in a concentric arrangement have been invented to obtain more design flexibility than can be obtained in single taller, wider toroidal inflatable structures (see figure). Originally intended for use as containers for habitats for humans in outer space or on remote planets, these and related prior inflatable structures could also be useful on Earth as lightweight, compactly stowable, portable special-purpose buildings that could be transported to remote locations and there inflated to full size and shape. In the case of a single inflatable toroidal structure, one important source of lack of design flexibility is the fact that an increase in outer diameter (which is sometimes desired) is necessarily accompanied by an increase in height (which is sometimes undesired). Increases in diameter and height can also cause difficulty in utilization of the resulting larger volume, in that it can become necessary to partition the volume by means of walls and floors, and features (e.g., stairs or ladders) must be added to enable vertical movement between floors. Moreover, ascending and descending between floors in a gravitational environment could pose unacceptable difficulty for the inhabitants under some circumstances. Another source of lack of design flexibility in a single toroidal inflatable structure is that for a given inflation pressure, an increase in the outer diameter of the structure necessarily entails an increase in the maximum stress in the structure. Because it is necessary to keep the maximum stress within the load-bearing capability of the structural materials, consistent with other aspects of the design, this may translate to a limit on the outer diameter. In an assembly comprising concentric nested toroidal structures, an increase in outer diameter does not necessarily entail an increase in height or a maximum stress in excess of the load-bearing capability of the structural
Spatial curvature falsifies eternal inflation
Kleban, Matthew; Schillo, Marjorie E-mail: mls604@nyu.edu
2012-06-01
Inflation creates large-scale cosmological density perturbations that are characterized by an isotropic, homogeneous, and Gaussian random distribution about a locally flat background. Even in a flat universe, the spatial curvature measured within one Hubble volume receives contributions from long wavelength perturbations, and will not in general be zero. These same perturbations determine the Cosmic Microwave Background (CMB) temperature fluctuations, which are O(10{sup −5}). Consequently, the low-l multipole moments in the CMB temperature map predict the value of the measured spatial curvature Ω{sub k}. On this basis we argue that a measurement of |Ω{sub k}| > 10{sup −4} would rule out slow-roll eternal inflation in our past with high confidence, while a measurement of Ω{sub k} < −10{sup −4} (which is positive curvature, a locally closed universe) rules out false-vacuum eternal inflation as well, at the same confidence level. In other words, negative curvature (a locally open universe) is consistent with false-vacuum eternal inflation but not with slow-roll eternal inflation, and positive curvature falsifies both. Near-future experiments will dramatically extend the sensitivity of Ω{sub k} measurements and constitute a sharp test of these predictions.
Topological phases of eternal inflation
Sekino, Yasuhiro; Shenker, Stephen; Susskind, Leonard
2010-06-15
''Eternal inflation'' is a term that describes a number of different phenomena that have been classified by Winitzki. According to Winitzki's classification, these phases can be characterized by the topology of the percolating structures in the inflating, 'white', region. In this paper we discuss these phases, the transitions between them, and the way they are seen by a 'Census Taker', a hypothetical observer inside the noninflating, 'black', region. We discuss three phases that we call 'black island', 'tubular', and 'white island'. The black island phase is familiar, composed of rare Coleman De Luccia bubble nucleation events. The Census Taker sees an essentially spherical boundary, described by the conformal field theory of the Friedmann-Robertson-Walker/conformal field theory (FRW/CFT) correspondence. In the tubular phase the Census Taker sees a complicated infinite genus structure composed of arbitrarily long tubes. The white island phase is even more mysterious from the black side. Surprisingly, when viewed from the noninflating region this phase resembles a closed, positively curved universe that eventually collapses to a singularity. Nevertheless, pockets of eternal inflation continue forever. In addition, there is an 'aborted' phase in which no eternal inflation takes place. Rigorous results of Chayes, Chayes, Grannan, and Swindle establish the existence of all of these phases, separated by first order transitions, in Mandelbrot percolation, a simple model of eternal inflation.
Standard-smooth hybrid inflation
Lazarides, George; Vamvasakis, Achilleas
2007-12-15
We consider the extended supersymmetric Pati-Salam model which, for {mu}>0 and universal boundary conditions, succeeds to yield experimentally acceptable b-quark masses by moderately violating Yukawa unification. It is known that this model can lead to new shifted or new smooth hybrid inflation. We show that a successful two-stage inflationary scenario can be realized within this model based only on renormalizable superpotential interactions. The cosmological scales exit the horizon during the first stage of inflation, which is of the standard hybrid type and takes place along the trivial flat direction with the inflaton driven by radiative corrections. Spectral indices compatible with the recent data can be achieved in global supersymmetry or minimal supergravity by restricting the number of e-foldings of our present horizon during the first inflationary stage. The additional e-foldings needed for solving the horizon and flatness problems are naturally provided by a second stage of inflation, which occurs mainly along the built-in new smooth hybrid inflationary path appearing right after the destabilization of the trivial flat direction at its critical point. Monopoles are formed at the end of the first stage of inflation and are, subsequently, diluted by the second stage of inflation to become utterly negligible in the present universe for almost all (for all) the allowed values of the parameters in the case of global supersymmetry (minimal supergravity)
NASA Astrophysics Data System (ADS)
Lello, Louis; Boyanovsky, Daniel; Holman, Richard
2014-03-01
If the large-scale anomalies in the temperature power spectrum of the cosmic microwave background are of primordial origin, they may herald modifications to the slow-roll inflationary paradigm on the largest scales. We study the possibility that the origin of the large-scale power suppression is a modification of initial conditions during slow roll as a result of a pre-slow-roll phase during which the inflaton evolves rapidly. This stage is manifest in a potential in the equations for the Gaussian fluctuations during slow roll and modifies the power spectra of scalar perturbations via an initial condition transfer function T(k). We provide a general analytical study of its large- and small-scale properties and analyze the impact of these initial conditions on the infrared aspects of typical test scalar fields. The infrared behavior of massless minimally coupled test scalar field theories leads to the dynamical generation of mass and anomalous dimensions, both depending nonanalytically on T(0). During inflation, all quanta decay into many quanta even of the same field because of the lack of kinematic thresholds. The decay leads to a quantum entangled state of subhorizon and superhorizon quanta with correlations across the horizon. We find the modifications of the decay width and the entanglement entropy from the initial conditions. In all cases, initial conditions from a "fast-roll" stage that lead to a suppression in the scalar power spectrum at large scales also result in a suppression of the dynamically generated masses, anomalous dimensions and decay widths.
Inflatable Antennas Support Emergency Communication
NASA Technical Reports Server (NTRS)
2010-01-01
Glenn Research Center awarded Small Business Innovation Research (SBIR) contracts to ManTech SRS Technologies, of Newport Beach, California, to develop thin film inflatable antennas for space communication. With additional funding, SRS modified the concepts for ground-based inflatable antennas. GATR (Ground Antenna Transmit and Receive) Technologies, of Huntsville, Alabama, licensed the technology and refined it to become the world s first inflatable antenna certified by the Federal Communications Commission. Capable of providing Internet access, voice over Internet protocol, e-mail, video teleconferencing, broadcast television, and other high-bandwidth communications, the systems have provided communication during the wildfires in California, after Hurricane Katrina in Mississippi, and following the 2010 Haiti earthquake.
NASA Astrophysics Data System (ADS)
Lin, Chia-Min; Cheung, Kingman
Following Ref. 10, we explore the parameter space of the case when the supersymmetry (SUSY) breaking scale is lower, for example, in gauge mediated SUSY breaking model. During inflation, the form of the potential is V0 plus MSSM (or A-term) inflation. We show that the model works for a wide range of the potential V0 with the soft SUSY breaking mass m O(1) TeV. The implication to MSSM (or A-term) inflation is that the flat directions which is lifted by the non-renormalizable terms described by the superpotential W=λ p φ p-1/Mp-3 P with p = 4 and p = 5 are also suitable to be an inflaton field for λp = O(1) provided there is an additional false vacuum term V0 with appropriate magnitude. The flat directions correspond to p = 6 also works for 0 < ˜ V0/M_ P4 < ˜ 10-40.
Scalar-tensor linear inflation
NASA Astrophysics Data System (ADS)
Artymowski, Michał; Racioppi, Antonio
2017-04-01
We investigate two approaches to non-minimally coupled gravity theories which present linear inflation as attractor solution: a) the scalar-tensor theory approach, where we look for a scalar-tensor theory that would restore results of linear inflation in the strong coupling limit for a non-minimal coupling to gravity of the form of f(varphi)R/2; b) the particle physics approach, where we motivate the form of the Jordan frame potential by loop corrections to the inflaton field. In both cases the Jordan frame potentials are modifications of the induced gravity inflationary scenario, but instead of the Starobinsky attractor they lead to linear inflation in the strong coupling limit.
Load limiting parachute inflation control
Redmond, J.; Hinnerichs, T.; Parker, G.
1994-01-01
Excessive deceleration forces experienced during high speed deployment of parachute systems can cause damage to the payload and the canopy fabric. Conventional reefing lines offer limited relief by temporarily restricting canopy inflation and limiting the peak deceleration load. However, the open-loop control provided by existing reefing devices restrict their use to a specific set of deployment conditions. In this paper, the sensing, processing, and actuation that are characteristic of adaptive structures form the basis of three concepts for active control of parachute inflation. These active control concepts are incorporated into a computer simulation of parachute inflation. Initial investigations indicate that these concepts promise enhanced performance as compared to conventional techniques for a nominal release. Furthermore, the ability of each controller to adapt to off-nominal release conditions is examined.
Downhole tool inflatable packer assembly
Brandell, J.T.
1984-07-10
A downhole tool inflatable packer assembly includes an upper packer shoe having a bypass mandrel connected thereto. A packer mandrel adapter has an upper end connected to a lower end of the bypass mandrel. A mandrel cover tube extends downwardly from the packer mandrel adapter. A packer mandrel has an upper portion connected to the packer mandrel adapter. A flow connector and a lower packer adapter are connected in that order below the packer mandrel. A packer flow tube has an upper end received in the bypass mandrel and a lower end received in the flow connector. An inflatable bladder has an upper end connected to the upper packer shoe and a lower end connected to a floating packer shoe which slidably engages the mandrel cover tube. A central flow passage, a packer bypass passage, and an inflation passage are disposed in the packer assembly.
Universality class in conformal inflation
Kallosh, Renata; Linde, Andrei E-mail: alinde@stanford.edu
2013-07-01
We develop a new class of chaotic inflation models with spontaneously broken conformal invariance. Observational consequences of a broad class of such models are stable with respect to strong deformations of the scalar potential. This universality is a critical phenomenon near the point of enhanced symmetry, SO(1,1), in case of conformal inflation. It appears because of the exponential stretching of the moduli space and the resulting exponential flattening of scalar potentials upon switching from the Jordan frame to the Einstein frame in this class of models. This result resembles stretching and flattening of inhomogeneities during inflationary expansion. It has a simple interpretation in terms of velocity versus rapidity near the Kähler cone in the moduli space, similar to the light cone of special theory of relativity. This effect makes inflation possible even in the models with very steep potentials. We describe conformal and superconformal versions of this cosmological attractor mechanism.
NASA Technical Reports Server (NTRS)
Hinson, W. F.; Keafer, L. S.
1984-01-01
It is proposed that for inflatable antenna systems, technology feasibility can be demonstrated and parametric design and scalability (scale factor 10 to 20) can be validated with an experiment using a 16-m-diameter antenna attached to the Shuttle. The antenna configuration consists of a thin film cone and paraboloid held to proper shape by internal pressure and a self-rigidizing torus. The cone and paraboloid would be made using pie-shaped gores with the paraboloid being coated with aluminum to provide reflectivity. The torus would be constructed using an aluminum polyester composite that when inflated would erect to a smooth shell that can withstand loads without internal pressure.
Open inflation in the landscape
NASA Astrophysics Data System (ADS)
Yamauchi, Daisuke; Linde, Andrei; Naruko, Atsushi; Sasaki, Misao; Tanaka, Takahiro
2011-08-01
The open inflation scenario is attracting a renewed interest in the context of the string landscape. Since there are a large number of metastable de Sitter vacua in the string landscape, tunneling transitions to lower metastable vacua through the bubble nucleation occur quite naturally, which leads to a natural realization of open inflation. Although the deviation of Ω0 from unity is small by the observational bound, we argue that the effect of this small deviation on the large-angle CMB anisotropies can be significant for tensor-type perturbation in the open inflation scenario. We consider the situation in which there is a large hierarchy between the energy scale of the quantum tunneling and that of the slow-roll inflation in the nucleated bubble. If the potential just after tunneling is steep enough, a rapid-roll phase appears before the slow-roll inflation. In this case the power spectrum is basically determined by the Hubble rate during the slow-roll inflation. On the other hand, if such a rapid-roll phase is absent, the power spectrum keeps the memory of the high energy density there in the large angular components. Furthermore, the amplitude of large angular components can be enhanced due to the effects of the wall fluctuation mode if the bubble wall tension is small. Therefore, although even the dominant quadrupole component is suppressed by the factor (1-Ω0)2, one can construct some models in which the deviation of Ω0 from unity is large enough to produce measurable effects. We also consider a more general class of models, where the false vacuum decay may occur due to Hawking-Moss tunneling, as well as the models involving more than one scalar field. We discuss scalar perturbations in these models and point out that a large set of such models is already ruled out by observational data, unless there was a very long stage of slow-roll inflation after the tunneling. These results show that observational data allow us to test various assumptions concerning
Anisotropic inflation from vector impurity
Kanno, Sugumi; Kimura, Masashi; Soda, Jiro; Yokoyama, Shuichiro E-mail: mkimura@sci.osaka-cu.ac.jp E-mail: shu@a.phys.nagoya-u.ac.jp
2008-08-15
We study an inflationary scenario with a vector impurity. We show that the universe undergoes anisotropic inflationary expansion due to a preferred direction determined by the vector. Using the slow roll approximation, we find a formula for determining the anisotropy of the inflationary universe. We discuss possible observable predictions of this scenario. In particular, it is stressed that primordial gravitational waves can be induced from curvature perturbations. Hence, even in low scale inflation, a sizable amount of primordial gravitational waves may be produced during inflation.
Dynamics of gauge field inflation
Alexander, Stephon; Jyoti, Dhrubo; Kosowsky, Arthur; Marcianò, Antonino
2015-05-05
We analyze the existence and stability of dynamical attractor solutions for cosmological inflation driven by the coupling between fermions and a gauge field. Assuming a spatially homogeneous and isotropic gauge field and fermion current, the interacting fermion equation of motion reduces to that of a free fermion up to a phase shift. Consistency of the model is ensured via the Stückelberg mechanism. We prove the existence of exactly one stable solution, and demonstrate the stability numerically. Inflation arises without fine tuning, and does not require postulating any effective potential or non-standard coupling.
Preventing eternality in phantom inflation
Feng Chaojun; Li Xinzhou; Saridakis, Emmanuel N.
2010-07-15
We have investigated the necessary conditions that prevent phantom inflation from being eternal. Allowing additionally for a nonminimal coupling between the phantom field and gravity, we present the slow-climb requirements, perform an analysis of the fluctuations, and finally we extract the overall conditions that are necessary in order to prevent eternality. Furthermore, we verify our results by solving explicitly the cosmological equations in a simple example of an exponential potential, formulating the classical motion plus the stochastic effect of the fluctuations through Langevin equations. Our analysis shows that phantom inflation can be finite without the need of additional exotic mechanisms.
Cosmological inflation and the quantum measurement problem
NASA Astrophysics Data System (ADS)
Martin, Jérôme; Vennin, Vincent; Peter, Patrick
2012-11-01
According to cosmological inflation, the inhomogeneities in our Universe are of quantum-mechanical origin. This scenario is phenomenologically very appealing as it solves the puzzles of the standard hot big bang model and naturally explains why the spectrum of cosmological perturbations is almost scale invariant. It is also an ideal playground to discuss deep questions among which is the quantum measurement problem in a cosmological context. Although the large squeezing of the quantum state of the perturbations and the phenomenon of decoherence explain many aspects of the quantum-to-classical transition, it remains to understand how a specific outcome can be produced in the early Universe, in the absence of any observer. The continuous spontaneous localization (CSL) approach to quantum mechanics attempts to solve the quantum measurement question in a general context. In this framework, the wave function collapse is caused by adding new nonlinear and stochastic terms to the Schrödinger equation. In this paper, we apply this theory to inflation, which amounts to solving the CSL parametric oscillator case. We choose the wave function collapse to occur on an eigenstate of the Mukhanov-Sasaki variable and discuss the corresponding modified Schrödinger equation. Then, we compute the power spectrum of the perturbations and show that it acquires a universal shape with two branches, one which remains scale invariant and one with nS=4, a spectral index in obvious contradiction with the cosmic microwave background anisotropy observations. The requirement that the non-scale-invariant part be outside the observational window puts stringent constraints on the parameter controlling the deviations from ordinary quantum mechanics. Due to the absence of a CSL amplification mechanism in field theory, this also has the consequence that the collapse mechanism of the inflationary fluctuations is not efficient. Then, we determine the collapse time. On small scales the collapse is
Inflatable Tubular Structures Rigidized with Foams
NASA Technical Reports Server (NTRS)
Tinker, Michael L.; Schnell, Andrew R.
2010-01-01
Inflatable tubular structures that have annular cross sections rigidized with foams, and the means of erecting such structures in the field, are undergoing development. Although the development effort has focused on lightweight structural booms to be transported in compact form and deployed in outer space, the principles of design and fabrication are also potentially applicable to terrestrial structures, including components of ultralightweight aircraft, lightweight storage buildings and shelters, lightweight insulation, and sales displays. The use of foams to deploy and harden inflatable structures was first proposed as early as the 1960s, and has been investigated in recent years by NASA, the U.S. Air Force Research Laboratory, industry, and academia. In cases of deployable booms, most of the investigation in recent years has focused on solid cross sections, because they can be constructed relatively easily. However, solid-section foam-filled booms can be much too heavy for some applications. In contrast, booms with annular cross sections according to the present innovation can be tailored to obtain desired combinations of stiffness and weight through choice of diameters, wall thicknesses, and foam densities. By far the most compelling advantage afforded by this innovation is the possibility of drastically reducing weights while retaining or increasing the stiffnesses, relative to comparable booms that have solid foamfilled cross sections. A typical boom according to this innovation includes inner and outer polyimide film sleeves to contain foam that is injected between them during deployment.
Air Tight: Building Inflatables/Inflatable Construction: Planning and Details
NASA Technical Reports Server (NTRS)
Kennedy, Kriss J.
2016-01-01
A design-build seminar consisting of students from Physics, Mechanical and Civil Engineering, Robotic, Material Science, Art, and Architecture who will work together on a deployable "closed-loop" inflatable greenhouse for Mars in theory, and an Earth analogue physical mockup on campus.
Primordial Inflation Polarization Explorer (Phase 3)
NASA Astrophysics Data System (ADS)
Kogut, Alan
This is the Lead Proposal for the investigation "Primordial Inflation Polarization Explorer (Phase 3)". We propose to complete and fly the Primordial Inflation Polarization Explorer (PIPER) to measure the polarization of the cosmic microwave background (CMB) and search for the imprint of gravitational waves produced during an inflationary epoch in the early universe. Detection of the inflationary signal would have profound consequences for both cosmology and high-energy physics. Not only would it establish inflation as a physical reality, it would provide a direct, model-independent determination of the relevant energy scale, shedding light on physics at energies twelve orders of magnitude beyond those accessible to direct experimentation in particle accelerators. The recent detection of CMB polarization by the BICEP2 instrument brings new urgency to the field. The BICEP2 detection at degree angular scales is consistent with inflation, but the amplitude is a factor of two higher than upper limits set by unpolarized data. A critical test is the rise in power at large angular scales predicted by inflation. Detecting this rise would confirm the signal's inflationary origin, fulfilling a long quest for cosmology while providing new insight into physics at the highest energies. PIPER is the only suborbital instrument capable of measuring CMB polarization on the large angular scales needed to test an inflationary origin for the BICEP2 detection. PIPER is a balloon-borne instrument, optimized to detect the inflationary signal on large angular scales. It consists of two co-aligned telescopes cooled to 1.5 K within a large liquid helium bucket dewar. A variable-delay polarization modulator (VPM) on each telescope chops between linear and circular polarization to isolate the polarized signal while rejecting the much brighter unpolarized emission. Four 32 x 40 element detector arrays provide background-limited sensitivity. A series of flights from mid-latitude sites will map
12 CFR 19.240 - Inflation adjustments.
Code of Federal Regulations, 2012 CFR
2012-01-01
... 12 Banks and Banking 1 2012-01-01 2012-01-01 false Inflation adjustments. 19.240 Section 19.240... PROCEDURE Civil Money Penalty Inflation Adjustments § 19.240 Inflation adjustments. (a) The maximum amount of each civil money penalty within the OCC's jurisdiction is adjusted in accordance with the...
77 FR 19937 - Inflatable Personal Flotation Devices
Federal Register 2010, 2011, 2012, 2013, 2014
2012-04-03
... using existing inflatable PFDs, and would enable marketing of existing inflatable PFDs to youth. The... approved, and thus does not affect the availability, use, or marketing of existing PFDs to or by the youth... marketing any inflatable PFD that is not approved by the Coast Guard (provided that it is not marked...
Grade Inflation in Higher Education. ERIC Digest.
ERIC Educational Resources Information Center
Young, Carol
Grade inflation has commanded increasing attention in the academic world in recent years, with administrators, faculty, and academic analysts unable to agree on whether grade inflation actually exists or is a myth to be debunked. This Digest reviews research in support of and against the existence of grade inflation. A statistical analysis report…
Is Grade Inflation Related to Faculty Status?
ERIC Educational Resources Information Center
Kezim, Boualem; Pariseau, Susan E.; Quinn, Frances
2005-01-01
The authors performed a statistical analysis to investigate whether grade inflation existed in the business school at a small private college in the northeast region of the United States. The results showed that grade inflation existed and exhibited a linear trend over a 20-year period. The authors found that grade inflation was related to faculty…
12 CFR 1780.80 - Inflation adjustments.
Code of Federal Regulations, 2011 CFR
2011-01-01
... 12 Banks and Banking 7 2011-01-01 2011-01-01 false Inflation adjustments. 1780.80 Section 1780.80... DEVELOPMENT RULES OF PRACTICE AND PROCEDURE RULES OF PRACTICE AND PROCEDURE Civil Money Penalty Inflation Adjustments § 1780.80 Inflation adjustments. The maximum amount of each civil money penalty within...
12 CFR 1780.80 - Inflation adjustments.
Code of Federal Regulations, 2010 CFR
2010-01-01
... 12 Banks and Banking 7 2010-01-01 2010-01-01 false Inflation adjustments. 1780.80 Section 1780.80... DEVELOPMENT RULES OF PRACTICE AND PROCEDURE RULES OF PRACTICE AND PROCEDURE Civil Money Penalty Inflation Adjustments § 1780.80 Inflation adjustments. The maximum amount of each civil money penalty within...
Does Education Corrupt? Theories of Grade Inflation
ERIC Educational Resources Information Center
Oleinik, Anton
2009-01-01
Several theories of grade inflation are discussed in this review article. It is argued that grade inflation results from the substitution of criteria specific to the search for truth by criteria of quality control generated outside of academia. Particular mechanisms of the grade inflation that occurs when a university is transformed into a…
Inflatable antennas for microwave pwoer transmission
NASA Technical Reports Server (NTRS)
Williams, Geoff
1989-01-01
Operational phase of the inflatable radiator; inflatable space structures; advantages; inflated thin-film satellites; antenna configuration; 3 meter diameter test paraboloid (HAIR program); and weight breakdown for the 100 meter diameter reflector are outlined. This presentation is represented by viewgraphs only.
Space Shuttle inflatable training articles
NASA Technical Reports Server (NTRS)
West, M. L.
1984-01-01
The design, development, construction, and testing of the Long Duration Exposure Facility inflatable and the space telescope training articles are discussed. While these articles are of similar nature, materials, and construction, they vary in size and present different problems with regards to size, shape, gross/net lift, and balance.
Langevin analysis of eternal inflation
Gratton, Steven; Turok, Neil
2005-08-15
It has been widely claimed that inflation is generically eternal to the future, even in models where the inflaton potential monotonically increases away from its minimum. The idea is that quantum fluctuations allow the field to jump uphill, thereby continually revitalizing the inflationary process in some regions. In this paper we investigate a simple model of this process, pertaining to {lambda}{phi}{sup 4} inflation, in which analytic progress may be made. We calculate several quantities of interest, such as the expected number of inflationary efolds, first without and then with various selection effects. With no additional weighting, the stochastic noise has little impact on the total number of inflationary efoldings in the model even if the inflaton starts with a Planckian energy density. A 'rolling' volume factor, i.e. weighting in proportion to the volume at that time, also leads to a monotonically decreasing Hubble constant and hence no eternal inflation. We show how stronger selection effects including a constraint on the initial and final states and weighting with the final volume factor can lead to a picture similar to that usually associated with eternal inflation.
Inflation as de Sitter instability
NASA Astrophysics Data System (ADS)
Cadoni, Mariano; Franzin, Edgardo; Mignemi, Salvatore
2016-09-01
We consider cosmological inflation generated by a scalar field slowly rolling off from a de Sitter maximum of its potential. The models belong to the class of hilltop models and represent the most general model of this kind in which the scalar potential can be written as the sum of two exponentials. The minimally coupled Einstein-scalar gravity theory obtained in this way is the cosmological version of a two-scale generalization of known holographic models, allowing for solitonic solutions interpolating between an AdS spacetime in the infrared and scaling solutions in the ultraviolet. We then investigate cosmological inflation in the slow-roll approximation. Our model reproduces correctly, for a wide range of its parameters, the most recent experimental data for the power spectrum of primordial perturbations. Moreover, it predicts inflation at energy scales of four to five orders of magnitude below the Planck scale. At the onset of inflation, the mass of the tachyonic excitation, i.e. of the inflaton, turns out to be seven to eight orders of magnitude smaller than the Planck mass.
Enqvist, Kari; Koivisto, Tomi; Rigopoulos, Gerasimos E-mail: T.S.Koivisto@astro.uio.no
2012-05-01
We consider inflation within the context of what is arguably the simplest non-metric extension of Einstein gravity. There non-metricity is described by a single graviscalar field with a non-minimal kinetic coupling to the inflaton field Ψ, parameterized by a single parameter γ. There is a simple equivalent description in terms of a massless field and an inflaton with a modified potential. We discuss the implications of non-metricity for chaotic inflation and find that it significantly alters the inflaton dynamics for field values Ψ∼>M{sub P}/γ, dramatically changing the qualitative behaviour in this regime. In the equivalent single-field description this is described as a cuspy potential that forms of barrier beyond which the inflation becomes a ghost field. This imposes an upper bound on the possible number of e-folds. For the simplest chaotic inflation models, the spectral index and the tensor-to-scalar ratio receive small corrections dependent on the non-metricity parameter. We also argue that significant post-inflationary non-metricity may be generated.
Anisotropic power-law inflation
Kanno, Sugumi; Soda, Jiro; Watanabe, Masa-aki E-mail: jiro@tap.scphys.kyoto-u.ac.jp
2010-12-01
We study an inflationary scenario in supergravity model with a gauge kinetic function. We find exact anisotropic power-law inflationary solutions when both the potential function for an inflaton and the gauge kinetic function are exponential type. The dynamical system analysis tells us that the anisotropic power-law inflation is an attractor for a large parameter region.
Topological phases of eternal inflation
NASA Astrophysics Data System (ADS)
Sekino, Yasuhiro; Shenker, Stephen; Susskind, Leonard
2010-06-01
“Eternal inflation” is a term that describes a number of different phenomena that have been classified by Winitzki. According to Winitzki’s classification, these phases can be characterized by the topology of the percolating structures in the inflating, “white,” region. In this paper we discuss these phases, the transitions between them, and the way they are seen by a “Census Taker,” a hypothetical observer inside the noninflating, “black,” region. We discuss three phases that we call “black island,” “tubular,” and “white island.” The black island phase is familiar, composed of rare Coleman De Luccia bubble nucleation events. The Census Taker sees an essentially spherical boundary, described by the conformal field theory of the Friedmann-Robertson-Walker/conformal field theory (FRW/CFT) correspondence. In the tubular phase the Census Taker sees a complicated infinite genus structure composed of arbitrarily long tubes. The white island phase is even more mysterious from the black side. Surprisingly, when viewed from the noninflating region this phase resembles a closed, positively curved universe that eventually collapses to a singularity. Nevertheless, pockets of eternal inflation continue forever. In addition, there is an “aborted” phase in which no eternal inflation takes place. Rigorous results of Chayes, Chayes, Grannan, and Swindle establish the existence of all of these phases, separated by first order transitions, in Mandelbrot percolation, a simple model of eternal inflation.
Curvaton and the inhomogeneous end of inflation
Assadullahi, Hooshyar; Wands, David; Firouzjahi, Hassan; Namjoo, Mohammad Hossein E-mail: firouz@mail.ipm.ir E-mail: david.wands@port.ac.uk
2012-12-01
We study the primordial density perturbations and non-Gaussianities generated from the combined effects of an inhomogeneous end of inflation and curvaton decay in hybrid inflation. This dual role is played by a single isocurvature field which is massless during inflation but acquire a mass at the end of inflation via the waterfall phase transition. We calculate the resulting primordial non-Gaussianity characterized by the non-linearity parameter, f{sub NL}, recovering the usual end-of-inflation result when the field decays promptly and the usual curvaton result if the field decays sufficiently late.
Mathematical issues in eternal inflation
NASA Astrophysics Data System (ADS)
Singh Kohli, Ikjyot; Haslam, Michael C.
2015-04-01
In this paper, we consider the problem of the existence and uniqueness of solutions to the Einstein field equations for a spatially flat Friedmann-Lemaître-Robertson-Walker universe in the context of stochastic eternal inflation, where the stochastic mechanism is modelled by adding a stochastic forcing term representing Gaussian white noise to the Klein-Gordon equation. We show that under these considerations, the Klein-Gordon equation actually becomes a stochastic differential equation. Therefore, the existence and uniqueness of solutions to Einstein’s equations depend on whether the coefficients of this stochastic differential equation obey Lipschitz continuity conditions. We show that for any choice of V(φ ), the Einstein field equations are not globally well-posed, hence, any solution found to these equations is not guaranteed to be unique. Instead, the coefficients are at best locally Lipschitz continuous in the physical state space of the dynamical variables, which only exist up to a finite explosion time. We further perform Feller’s explosion test for an arbitrary power-law inflaton potential and prove that all solutions to the Einstein field equations explode in a finite time with probability one. This implies that the mechanism of stochastic inflation thus considered cannot be described to be eternal, since the very concept of eternal inflation implies that the process continues indefinitely. We therefore argue that stochastic inflation based on a stochastic forcing term would not produce an infinite number of universes in some multiverse ensemble. In general, since the Einstein field equations in both situations are not well-posed, we further conclude that the existence of a multiverse via the stochastic eternal inflation mechanism considered in this paper is still very much an open question that will require much deeper investigation.
Length of Inflation and Non-Gaussianity
NASA Astrophysics Data System (ADS)
Hirai, Shiro; Takami, Tomoyuki
Certain inflation models are shown to have large non-Gaussianity in special cases. Namely, slow-roll inflation models with an effective higher derivative interaction, in which the length of inflation is finite and a scalar-matter-dominated period or power inflation is adopted as pre-inflation, are considered. Using Holman and Tolley's formula of the nonlinearity parameter in the flattened triangle configurations f flattened NL, we calculate the value of f flattened NL. The value of f flattened NL is found to be largest (f flattened NL>10) when the inflation length is approximately 60 e-folds, and f flattened NL is found to depend strongly on the length of inflation and the cut-off scale.
The big bang and inflation united by an analytic solution
Bars, Itzhak; Chen, Shih-Hung
2011-02-15
Exact analytic solutions for a class of scalar-tensor gravity theories with a hyperbolic scalar potential are presented. Using an exact solution we have successfully constructed a model of inflation that produces the spectral index, the running of the spectral index, and the amplitude of scalar perturbations within the constraints given by the WMAP 7 years data. The model simultaneously describes the big bang and inflation connected by a specific time delay between them so that these two events are regarded as dependent on each other. In solving the Friedmann equations, we have utilized an essential Weyl symmetry of our theory in 3+1 dimensions which is a predicted remaining symmetry of 2T-physics field theory in 4+2 dimensions. This led to a new method of obtaining analytic solutions in the 1T field theory which could in principle be used to solve more complicated theories with more scalar fields. Some additional distinguishing properties of the solution includes the fact that there are early periods of time when the slow-roll approximation is not valid. Furthermore, the inflaton does not decrease monotonically with time; rather, it oscillates around the potential minimum while settling down, unlike the slow-roll approximation. While the model we used for illustration purposes is realistic in most respects, it lacks a mechanism for stopping inflation. The technique of obtaining analytic solutions opens a new window for studying inflation, and other applications, more precisely than using approximations.
Primordial Inflation Polarization Explorer (Phase 2)
NASA Astrophysics Data System (ADS)
Kogurt, Alan; Bennett, Charles
This is the Lead Proposal for the proposed investigation "Primordial Inflation Polarization Explorer (Phase 2)" We propose to fly the Primordial Inflation Polarization Explorer (PIPER) to measure the polarization of the cosmic microwave background (CMB) and search for the imprint of gravitational waves produced during an inflationary epoch in the early universe. Such a signal is expected to exist: the simplest inflation models predict tensor-to-scalar ratio 0.01 < r < 0.16 corresponding to detectable amplitudes in the range 30--100 nK. Detection of the inflationary signal would have profound consequences for both cosmology and high-energy physics. Not only would it establish inflation as a physical reality, it would provide a direct, model- independent determination of the relevant energy scale, shedding light on physics at energies twelve orders of magnitude beyond those accessible to direct experimentation in particle accelerators. PIPER is a balloon-borne instrument optimized to detect the inflationary signal on large angular scales. It consists of two co-aligned telescopes cooled to 1.5 K within a large liquid helium bucket dewar. A variable-delay polarization modulator (VPM) on each telescope chops between linear and circular polarization to isolate the polarized signal while rejecting the much brighter unpolarized emission. PIPER's innovative architecture combines cryogenic optics with kilo-pixel detector arrays to provide unprecedented sensitivity to CMB polarization. The fast modulation between linear and circular polarization takes advantage of the lack of astrophysical circular polarization to eliminate common sources of systematic error. The sensitivity and control of systematic errors in turn enable measurements over most of the sky from mid-latitude launch sites; long-duration Antarctic flights are not required. With sensitivity r < 0.007 at 95% CL, PIPER will either detect the inflationary signal or rule out nearly all large-field inflation models
Advanced Structural and Inflatable Hybrid Spacecraft Module
NASA Technical Reports Server (NTRS)
Schneider, William C. (Inventor); delaFuente, Horacio M. (Inventor); Edeen, Gregg A. (Inventor); Kennedy, Kriss J. (Inventor); Lester, James D. (Inventor); Gupta, Shalini (Inventor); Hess, Linda F. (Inventor); Lin, Chin H. (Inventor); Malecki, Richard H. (Inventor); Raboin, Jasen L. (Inventor)
2001-01-01
An inflatable module comprising a structural core and an inflatable shell, wherein the inflatable shell is sealingly attached to the structural core. In its launch configuration, the wall thickness of the inflatable shell is collapsed by vacuum. Also in this configuration, the inflatable shell is collapsed and efficiently folded around the structural core. Upon deployment, the wall thickness of the inflatable shell is inflated; whereby the inflatable shell itself, is thereby inflated around the structural core, defining therein a large enclosed volume. A plurality of removable shelves are arranged interior to the structural core in the launch configuration. The structural core also includes at least one longeron that, in conjunction with the shelves, primarily constitute the rigid, strong, and lightweight load-bearing structure of the module during launch. The removable shelves are detachable from their arrangement in the launch configuration so that, when the module is in its deployed configuration and launch loads no longer exist, the shelves can be rearranged to provide a module interior arrangement suitable for human habitation and work. In the preferred embodiment, to provide efficiency in structural load paths and attachments, the shape of the inflatable shell is a cylinder with semi-toroidal ends.
Planck constraints on monodromy inflation
Easther, Richard; Flauger, Raphael E-mail: flauger@ias.edu
2014-02-01
We use data from the nominal Planck mission to constrain modulations in the primordial power spectrum associated with monodromy inflation. The largest improvement in fit relative to the unmodulated model has Δχ{sup 2} ≈ 10 and we find no evidence for a primordial signal, in contrast to a previous analysis of the WMAP9 dataset, for which Δχ{sup 2} ≈ 20. The Planck and WMAP9 results are broadly consistent on angular scales where they are expected to agree as far as best-fit values are concerned. However, even on these scales the significance of the signal is reduced in Planck relative to WMAP, and is consistent with a fit to the ''noise'' associated with cosmic variance. Our results motivate both a detailed comparison between the two experiments and a more careful study of the theoretical predictions of monodromy inflation.
Ilic, Stephane; Kunz, Martin; Liddle, Andrew R.; Frieman, Joshua A.
2010-05-15
Traditionally, inflationary models are analyzed in terms of parameters such as the scalar spectral index n{sub s} and the tensor to scalar ratio r, while dark energy models are studied in terms of the equation of state parameter w. Motivated by the fact that both deal with periods of accelerated expansion, we study the evolution of w during inflation, in order to derive observational constraints on its value during an earlier epoch likely dominated by a dynamic form of dark energy. We find that the cosmic microwave background and large-scale structure data is consistent with w{sub inflation}=-1 and provides an upper limit of 1+w < or approx. 0.02. Nonetheless, an exact de Sitter expansion with a constant w=-1 is disfavored since this would result in n{sub s}=1.
Permutation on hybrid natural inflation
NASA Astrophysics Data System (ADS)
Carone, Christopher D.; Erlich, Joshua; Ramos, Raymundo; Sher, Marc
2014-09-01
We analyze a model of hybrid natural inflation based on the smallest non-Abelian discrete group S3. Leading invariant terms in the scalar potential have an accidental global symmetry that is spontaneously broken, providing a pseudo-Goldstone boson that is identified as the inflaton. The S3 symmetry restricts both the form of the inflaton potential and the couplings of the inflaton field to the waterfall fields responsible for the end of inflation. We identify viable points in the model parameter space. Although the power in tensor modes is small in most of the parameter space of the model, we identify parameter choices that yield potentially observable values of r without super-Planckian initial values of the inflaton field.
Ivanov, Mikhail M.; Sibiryakov, Sergey E-mail: sergey.sibiryakov@cern.ch
2014-05-01
We present a setup that provides a partial UV-completion of the ghost inflation model up to a scale which can be almost as high as the Planck mass. This is achieved by coupling the inflaton to the Lorentz-violating sector described by the Einstein-aether theory or its khronometric version. Compared to previous works on ghost inflation our setup allows to go beyond the study of small perturbations and include the background dynamics in a unified framework. In the specific regime when the expansion of the Universe is dominated by the kinetic energy of the inflaton we find that the model predicts rather high tensor-to-scalar ratio r ∼ 0.02÷0.2 and non-Gaussianity of equilateral type with f{sub NL} in the range from -50 to -5.
Fluid physics of parachute inflation
Peterson, C.W. )
1993-08-01
This article describes the physics of the motion of the parachute and the surrounding air as the parachute emerges from the payload, inflates, and decelerates the payload. Precise calculation of parachute deployment, inflation and payload deceleration requires solution of the nonlinear, time-dependent equations of motion for turbulent, separated airflow around and through the parachute coupled to the equations of motion of the parachute. Because of the difficulty of this problem, parachute designers have for many years relied on empirical methods rather than on analysis. A description is given of the attempts to model the important events numerically so that parachutes can someday be designed on computers instead of by trial-and-error flight tests. 3 refs., 7 figs.
Ferrara, Sergio; Roest, Diederik
2016-10-24
We prove that all inflationary models, including those with dark energy after the end of inflation, can be embedded in minimal supergravity with a single chiral superfield. Moreover, the amount of supersymmetry breaking is independently tunable due to a degeneracy in the choice for the superpotential. The inflaton is a scalar partner of the Goldstino in this set-up. We illustrate our general procedure with two examples that are favoured by the Planck data.
Sneutrino chaotic inflation and landscape
NASA Astrophysics Data System (ADS)
Murayama, Hitoshi; Nakayama, Kazunori; Takahashi, Fuminobu; Yanagida, Tsutomu T.
2014-11-01
The most naive interpretation of the BICEP2 data is the chaotic inflation by an inflaton with a quadratic potential. When combined with supersymmetry, we argue that the inflaton plays the role of right-handed scalar neutrino based on rather general considerations. The framework suggests that the right-handed sneutrino tunneled from a false vacuum in a landscape to our vacuum with a small negative curvature and suppressed scalar perturbations at large scales.
Duality cascade in brane inflation
Bean, Rachel; Chen Xingang; Hailu, Girma; Henry Tye, S-H; Xu Jiajun E-mail: xgchen@mit.edu E-mail: tye@lepp.cornell.edu
2008-03-15
We show that brane inflation is very sensitive to tiny sharp features in extra dimensions, including those in the potential and in the warp factor. This can show up as observational signatures in the power spectrum and/or non-Gaussianities of the cosmic microwave background radiation (CMBR). One general example of such sharp features is a succession of small steps in a warped throat, caused by Seiberg duality cascade using gauge/gravity duality. We study the cosmological observational consequences of these steps in brane inflation. Since the steps come in a series, the prediction of other steps and their properties can be tested by future data and analysis. It is also possible that the steps are too close to be resolved in the power spectrum, in which case they may show up only in the non-Gaussianity of the CMB temperature fluctuations and/or EE polarization. We study two cases. In the slow-roll scenario, where steps appear in the inflaton potential, the sensitivity of brane inflation to the height and width of the steps is increased by several orders of magnitude compared to that in previously studied large field models. In the IR DBI scenario, where steps appear in the warp factor, we find that the glitches in the power spectrum caused by these sharp features are generally small or even unobservable, but associated distinctive non-Gaussianity can be large. Together with its large negative running of the power spectrum index, this scenario clearly illustrates how rich and different a brane inflationary scenario can be when compared to generic slow-roll inflation. Such distinctive stringy features may provide a powerful probe of superstring theory.
Chaotic inflation and supersymmetry breaking
Kallosh, Renata; Linde, Andrei; Rube, Tomas; Olive, Keith A.
2011-10-15
We investigate the recently proposed class of chaotic inflation models in supergravity with an arbitrary inflaton potential V({phi}). These models are extended to include matter fields in the visible sector and we employ a mechanism of supersymmetry breaking based on a particular phenomenological version of the KKLT mechanism (the KL model). We describe specific features of reheating in this class of models and show how one can solve the cosmological moduli and gravitino problems in this context.
Inflation in the scaling limit
Matarrese, S.; Ortolan, A.; Lucchin, F.
1989-07-15
We investigate the stochastic dynamics of the/ital inflaton/ for a wide class of potentials leading either tochaotic or to power-law inflation.At late times the system enters a /ital scaling/ /ital regime/where macroscopic order sets in: the field distribution sharply peaksaround the classical slow-rollover configuration and curvature perturbationsoriginate with a non-Gaussian scale-invariant statistics.
Reheating for closed string inflation
Cicoli, Michele; Mazumdar, Anupam E-mail: a.mazumdar@lancaster.ac.uk
2010-09-01
We point out some of the outstanding challenges for embedding inflationary cosmology within string theory studying the process of reheating for models where the inflaton is a closed string mode parameterising the size of an internal cycle of the compactification manifold. A realistic model of inflation must explain the tiny perturbations in the cosmic microwave background radiation and also how to excite the ordinary matter degrees of freedom after inflation, required for the success of Big Bang Nucleosynthesis. We study these issues focusing on two promising inflationary models embedded in LARGE volume type IIB flux compactifications. We show that phenomenological requirements and consistency of the effective field theory treatment imply the presence at low energies of a hidden sector together with a visible sector, where the Minimal Supersymmetric Standard Model fields are residing. A detailed calculation of the inflaton coupling to the fields of the hidden sector, visible sector, and moduli sector, reveals that the inflaton fails to excite primarily the visible sector fields, instead hidden sector fields are excited copiously after the end of inflation. This sets severe constraints on hidden sector model building where the most promising scenario emerges as a pure N = 1 SYM theory, forbidding the kinematical decay of the inflaton to the hidden sector. In this case it is possible to reheat the Universe with the visible degrees of freedom even though in some cases we discover a new tension between TeV scale SUSY and reheating on top of the well-known tension between TeV scale SUSY and inflation.
Unity of cosmological inflation attractors.
Galante, Mario; Kallosh, Renata; Linde, Andrei; Roest, Diederik
2015-04-10
Recently, several broad classes of inflationary models have been discovered whose cosmological predictions, in excellent agreement with Planck, are stable with respect to significant modifications of the inflaton potential. Some classes of models are based on a nonminimal coupling to gravity. These models, which we call ξ attractors, describe universal cosmological attractors (including Higgs inflation) and induced inflation models. Another class describes conformal attractors (including Starobinsky inflation and T models) and their generalization to α attractors. The aim of this Letter is to elucidate the common denominator of these attractors: their robust predictions stem from a joint pole of order 2 in the kinetic term of the inflaton field in the Einstein frame formulation prior to switching to the canonical variables. Model-dependent differences only arise at subleading level in the kinetic term. As a final step towards the unification of the different attractors, we introduce a special class of ξ attractors which is fully equivalent to α attractors with the identification α=1+(1/6ξ). While r is generically predicted to be of the order 1/N^{2}, there is no theoretical lower bound on r in this class of models.
Inflection point inflation within supersymmetry
Enqvist, Kari; Mazumdar, Anupam; Stephens, Philip E-mail: a.mazumdar@lancaster.ac.uk
2010-06-01
We propose to address the fine tuning problem of inflection point inflation by the addition of extra vacuum energy that is present during inflation but disappears afterwards. We show that in such a case, the required amount of fine tuning is greatly reduced. We suggest that the extra vacuum energy can be associated with an earlier phase transition and provide a simple model, based on extending the SM gauge group to SU(3){sub C} × SU(2){sub L} × U(1){sub Y} × U(1){sub B−L}, where the Higgs field of U(1){sub B−L} is in a false vacuum during inflation. In this case, there is virtually no fine tuning of the soft SUSY breaking parameters of the flat direction which serves as the inflaton. However, the absence of radiative corrections which would spoil the flatness of the inflaton potential requires that the U(1){sub B−L} gauge coupling should be small with g{sub B−L} ≤ 10{sup −4}.
Generalised tensor fluctuations and inflation
Cannone, Dario; Tasinato, Gianmassimo; Wands, David E-mail: g.tasinato@swansea.ac.uk
2015-01-01
Using an effective field theory approach to inflation, we examine novel properties of the spectrum of inflationary tensor fluctuations, that arise when breaking some of the symmetries or requirements usually imposed on the dynamics of perturbations. During single-clock inflation, time-reparameterization invariance is broken by a time-dependent cosmological background. In order to explore more general scenarios, we consider the possibility that spatial diffeomorphism invariance is also broken by effective mass terms or by derivative operators for the metric fluctuations in the Lagrangian. We investigate the cosmological consequences of the breaking of spatial diffeomorphisms, focussing on operators that affect the power spectrum of fluctuations. We identify the operators for tensor fluctuations that can provide a blue spectrum without violating the null energy condition, and operators for scalar fluctuations that lead to non-conservation of the comoving curvature perturbation on superhorizon scales even in single-clock inflation. In the last part of our work, we also examine the consequences of operators containing more than two spatial derivatives, discussing how they affect the sound speed of tensor fluctuations, and showing that they can mimic some of the interesting effects of symmetry breaking operators, even in scenarios that preserve spatial diffeomorphism invariance.
Testing split supersymmetry with inflation
NASA Astrophysics Data System (ADS)
Craig, Nathaniel; Green, Daniel
2014-07-01
Split supersymmetry (SUSY) — in which SUSY is relevant to our universe but largely inaccessible at current accelerators — has become increasingly plausible given the absence of new physics at the LHC, the success of gauge coupling unification, and the observed Higgs mass. Indirect probes of split SUSY such as electric dipole moments (EDMs) and flavor violation offer hope for further evidence but are ultimately limited in their reach. Inflation offers an alternate window into SUSY through the direct production of superpartners during inflation. These particles are capable of leaving imprints in future cosmological probes of primordial non-gaussianity. Given the recent observations of BICEP2, the scale of inflation is likely high enough to probe the full range of split SUSY scenarios and therefore offers a unique advantage over low energy probes. The key observable for future experiments is equilateral non-gaussianity, which will be probed by both cosmic microwave background (CMB) and large scale structure (LSS) surveys. In the event of a detection, we forecast our ability to find evidence for superpartners through the scaling behavior in the squeezed limit of the bispectrum.
BICEP2 constrains composite inflation
NASA Astrophysics Data System (ADS)
Channuie, Phongpichit
2014-07-01
In light of BICEP2, we re-examine single field inflationary models in which the inflation is a composite state stemming from various four-dimensional strongly coupled theories. We study in the Einstein frame a set of cosmological parameters, the primordial spectral index ns and tensor-to-scalar ratio r, predicted by such models. We confront the predicted results with the joint Planck data, and with the recent BICEP2 data. We constrain the number of e-foldings for composite models of inflation in order to obtain a successful inflation. We find that the minimal composite inflationary model is fully consistent with the Planck data. However it is in tension with the recent BICEP2 data. The observables predicted by the glueball inflationary model can be consistent with both Planck and BICEP2 contours if a suitable number of e-foldings are chosen. Surprisingly, the super Yang-Mills inflationary prediction is significantly consistent with the Planck and BICEP2 observations.
Inflation on an Open Racetrack
Chen, Heng-Yu; Hung, Ling-Yan; Shiu, Gary; /Wisconsin U., Madison /SLAC /Stanford U., Phys. Dept.
2011-11-14
We present a variant of warped D-brane inflation by incorporating multiple sets of holomorphically - embedded D7-branes involved in moduli stabilization with extent into a warped throat. The resultant D3-brane motion depends on the D7-brane configuration and the relative position of the D3-brane in these backgrounds. The non-perturbative moduli stabilization superpotential takes the racetrack form, but the additional D3-brane open string moduli dependence provides more flexibilities in model building. For concreteness, we consider D3-brane motion in the warped deformed conifold with the presence of multiple D7-branes, and derive the scalar potential valid for the entire throat. By explicit tuning of the microphysical parameters, we obtain inflationary trajectories near an inflection point for various D7-brane configurations. Moreover, the open racetrack potential admits approximate Minkowski vacua before uplifting. We demonstrate with a concrete D-brane inflation model where the Hubble scale during inflation can exceed the gravitino mass. Finally, the multiple sets of D7-branes present in this open racetrack setup also provides a mechanism to stabilize the D3-brane to metastable vacua in the intermediate region of the warped throat.
Bouncing braneworld cosmologies and initial conditions to inflation
Maier, R.; Soares, I. Damiao; Tonini, E. V.
2009-01-15
We examine the full nonlinear dynamics of closed Friedmann-Robertson-Walker universes in the framework of D-branes formalism. Friedmann equations contain additional terms arising from the bulk-brane interaction that provide a concrete model for nonsingular bounces in the early phase of the Universe. We construct nonsingular cosmological scenarios sourced with perfect fluids and a massive inflaton field, which are past eternal, oscillatory, and may emerge into an inflationary phase due to nonlinear resonance mechanisms. Oscillatory behavior becomes metastable when the system is driven into a resonance window of the parameter space of the models, with consequent breakup of KAM tori that trap the inflaton, leading the Universe to the inflationary regime. A construction of the resonance chart of the models is made. Resonance windows are labeled by an integer n{>=}2, where n is related to the ratio of the frequencies in the scale factor/scalar field degrees of freedom. They are typically small compared to the volume of the whole parameter space, and we examine the constraints imposed by nonlinear resonance in the physical domain of initial configurations so that inflation may be realized. We discuss the complex dynamics arising in this preinflationary stage, the structural stability of the resonance pattern and some of its possible imprints in the physics of inflation. We also approach the issue of initial configurations that are connected to a chaotic exit to inflation. Pure scalar field bouncing cosmologies are constructed. Contrary to models with perfect fluid components, the structure of the bouncing dynamics is highly sensitive to the initial amplitude and to the mass of the inflaton; dynamical potential barriers allowing for bounces appear as a new feature of the dynamics. We argue that if our actual Universe is a brane inflated by a parametric resonance mechanism triggered by the inflaton, some observable cosmological parameters should then have a signature of
Energy density of relic gravity waves from inflation
Sahni, V. )
1990-07-15
We evaluate both the spectral energy density and the total energy density for relic gravity waves produced during the transition from an early inflationary phase to a matter-dominated Friedmann-Robertson-Walker-type expansion: {ital a}{similar to}{ital t}{sup {ital c}} ({ital c}{lt}1). We find that for power-law inflation the spectral energy density for gravity waves has more power on larger scales than for purely exponential inflation. Evaluating the energy density of created massless particles (both gravitons and massless scalars) we find that in the case of exponential inflation the ratio of the density of created particles to the total density of matter is a constant, if {ital c}{ge}1/2. This unusual behavior is a consequence of the fact that the equation of state for created particles mimics the equation of state for matter driving the expansion of the Universe. As a result, self-consistent solutions of the Einstein equations can be found, in which the expansion of the Universe is sustained solely by the ongoing production of massless particles, so that {ital G}{sub {mu}{nu}}=8{pi}{ital G}{l angle}{ital T}{sub {mu}{nu}}{r angle}. In the case of power-law and quasiexponential inflation we find that the ratio of the energy density of gravity waves to the background matter density increases with time, as gravity waves with longer wavelengths and larger amplitudes enter the horizon at successively later epochs. This could lead to the energy density of gravity waves becoming comparable to the energy density of matter at late times, if inflation commenced at Planckian energies.
Vacuum transitions and eternal inflation
NASA Astrophysics Data System (ADS)
Johnson, Matthew C.
In this thesis, we focus on aspects of inflation and eternal inflation arising in scalar field theories coupled to gravity which possess a number of metastable states. Such theories contain instantons that interpolate between the metastable potential minima, corresponding to the nucleation of bubbles containing a new phase in a background of the old phase. In the first part of this thesis, we describe the classical dynamics and quantum nucleation of vacuum bubbles. We classify all possible spherically symmetric, thin-wall solutions with arbitrary interior and exterior cosmological constant, and find that bubbles possessing a turning point are unstable to aspherical perturbations. Next, we turn to the quantum nucleation of bubbles with zero mass. Focusing on instantons interpolating between positive and negative energy minima, we find that there exists a "Great Divide" in the space of potentials, across which the lifetime of metastable states differs drastically. Generalizing a semi-classical Hamiltonian formalism to treat the nucleation of bubbles with nonzero mass, we show that a number of tunneling mechanisms can be unified in the thin-wall limit, and directly compare their probabilities. In the second part of this thesis, we discuss the measure problem in eternal inflation. We give a detailed analysis of the prospects for making predictions in eternal inflation, and describe the existing probability measures and the connections between them. We then show that all existing measures exhibit a number of rather generic phenomena, for example strongly weighting vacua that can undergo rapid transitions between each other. It is argued that making predictions will require a measure that weights histories as opposed to vacua, and we develop a formalism to addresses this. Finally, we assess the prospects for observing collisions between vacuum bubbles in an eternally inflating universe. Contrary to conventional wisdom, we find that under certain assumptions most
Grade inflation: should we be concerned?
Scanlan, Judith M; Care, W Dean
2004-10-01
Grade inflation is defined as an increase in grade point average without an associated increase in overall student ability. The literature supports the idea that grade inflation is rampant throughout higher education. Shoemaker and DeVos described the scope of the problem in higher education in general and note the lack of existing empirical information in nursing education. Given the perceived problem in faculties of nursing, the widespread nature of the issue of grade inflation across universities and colleges, and the lack of empirical data, understanding the nature of grade inflation is important. This article will discuss a study designed to investigate the extent to which grade inflation is an issue within a western Canadian faculty of nursing. Recommendations related to grade inflation are discussed.
Inflation of Unreefed and Reefed Extraction Parachutes
NASA Technical Reports Server (NTRS)
Ray, Eric S.; Varela, Jose G.
2015-01-01
Data from the Orion and several other test programs have been used to reconstruct inflation parameters for 28 ft Do extraction parachutes as well as the parent aircraft pitch response during extraction. The inflation force generated by extraction parachutes is recorded directly during tow tests but is usually inferred from the payload accelerometer during Low Velocity Airdrop Delivery (LVAD) flight test extractions. Inflation parameters are dependent on the type of parent aircraft, number of canopies, and standard vs. high altitude extraction conditions. For standard altitudes, single canopy inflations are modeled as infinite mass, but the non-symmetric inflations in a cluster are modeled as finite mass. High altitude extractions have necessitated reefing the extraction parachutes, which are best modeled as infinite mass for those conditions. Distributions of aircraft pitch profiles and inflation parameters have been generated for use in Monte Carlo simulations of payload extractions.
Graceful exit from Higgs G inflation
NASA Astrophysics Data System (ADS)
Kamada, Kohei; Kobayashi, Tsutomu; Kunimitsu, Taro; Yamaguchi, Masahide; Yokoyama, Jun'ichi
2013-12-01
Higgs G inflation is a Higgs inflation model with a generalized Galileon term added to the standard model Higgs field, which realizes inflation compatible with observations. Recently, it was claimed that the generalized Galileon term induces instabilities during the oscillation phase and that the simplest Higgs G-inflation model inevitably suffers from this problem. In this paper, we extend the original Higgs G-inflation Lagrangian to a more general form, namely introducing a higher-order kinetic term and generalizing the form of the Galileon term, so that the Higgs field can oscillate after inflation without encountering instabilities. Moreover, it accommodates a large region of the ns-r plane, most of which is consistent with current observations, leading us to expect the detection of B-mode polarization in the cosmic microwave background in the near future.
Microwave background anisotropies in quasiopen inflation
NASA Astrophysics Data System (ADS)
García-Bellido, Juan; Garriga, Jaume; Montes, Xavier
1999-10-01
Quasiopenness seems to be generic to multifield models of single-bubble open inflation. Instead of producing infinite open universes, these models actually produce an ensemble of very large but finite inflating islands. In this paper we study the possible constraints from CMB anisotropies on existing models of open inflation. The effect of supercurvature anisotropies combined with the quasiopenness of the inflating regions make some models incompatible with observations, and severely reduces the parameter space of others. Supernatural open inflation and the uncoupled two-field model seem to be ruled out due to these constraints for values of Ω0<~0.98. Others, such as the open hybrid inflation model with suitable parameters for the slow roll potential can be made compatible with observations.
Scale invariance and a gravitational model with non-eternal inflation
Herdeiro, Carlos; Hirano, Shinji E-mail: hirano@eken.phys.nagoya-u.ac.jp
2012-05-01
We propose a 3+1 dimensional model of gravity which results in inflation at early times, followed by radiation- and matter-dominated epochs and a subsequent acceleration at late times. Both the inflation and late time acceleration are nearly de Sitter with a large hierarchy between the effective cosmological constants. There is no scalar field agent of inflation, and the transition from the inflation to the radiation-dominated period is smooth. This model is designed so that it yields, at the cost of giving up on Lorentz invariance in the gravitational sector, the Dirac-Born-Infeld type conformal scalar theory when the universe is conformally flat. It, however, resembles Einstein's gravity with the Gibbons-Hawking-York boundary term in weakly curved space-times.
New Sources of Gravitational Waves During Inflation
Senatore, Leonardo; Silverstein, Eva; Zaldarriaga, Matias; /Princeton, Inst. Advanced Study
2012-02-15
We point out that detectable inflationary tensor modes can be generated by particle or string sources produced during inflation, consistently with the requirements for inflation and constraints from scalar fluctuations. We show via examples that this effect can dominate over the contribution from quantum fluctuations of the metric, occurring even when the inflationary potential energy is too low to produce a comparable signal. Thus a detection of tensor modes from inflation does not automatically constitute a determination of the inflationary Hubble scale.
Built-in inflation in f(G) gravity
NASA Astrophysics Data System (ADS)
Sharif, M.; Fatima, H. Ismat
2016-10-01
In this paper, we study the role of Gauss-Bonnet term for the early and late time accelerating phases of the universe with the help of two viable f(G) models in the background of flat FRW universe model. These models show inflationary behavior as well as the present accelerating expansion of the universe. The contribution of Gauss-Bonnet term in pressure and energy density is used to calculate equation of state (EoS) parameter for the modified fluid which behaves like cosmological constant with \\Hdot = 0. We discuss early inflation and late accelerating expansion of the universe through scale factor evaluated from equation of continuity numerically.
HIAD-2 (Hypersonic Inflatable Aerodynamic Decelerator)
The Hypersonic Inflatable Aerodynamic Decelerator (HIAD) project is a disruptive technology that will accommodate the atmospheric entry of heavy payloads to planetary bodies such as Mars. HIAD over...
Dynamic Deployment Simulations of Inflatable Space Structures
NASA Technical Reports Server (NTRS)
Wang, John T.
2005-01-01
The feasibility of using Control Volume (CV) method and the Arbitrary Lagrangian Eulerian (ALE) method in LSDYNA to simulate the dynamic deployment of inflatable space structures is investigated. The CV and ALE methods were used to predict the inflation deployments of three folded tube configurations. The CV method was found to be a simple and computationally efficient method that may be adequate for modeling slow inflation deployment sine the inertia of the inflation gas can be neglected. The ALE method was found to be very computationally intensive since it involves the solving of three conservative equations of fluid as well as dealing with complex fluid structure interactions.
Cosmological magnetic fields from inflation and backreaction
Kanno, Sugumi; Soda, Jiro; Watanabe, Masa-aki E-mail: jiro@tap.scphys.kyoto-u.ac.jp
2009-12-01
We study the backreaction problem in a mechanism of magnetogenesis from inflation. In usual analysis, it has been assumed that the backreaction due to electromagnetic fields spoils inflation once it becomes important. However, there exists no justification for this assumption. Hence, we analyze magnetogenesis from inflation by taking into account the backreaction. On the contrary to the naive expectation, we show that inflation still continues even after the backreaction begins to work. Nevertheless, it turns out that creation of primordial magnetic fields is significantly suppressed due to the backreaction.
Testing the Standard Model with the Primordial Inflation Explorer
NASA Technical Reports Server (NTRS)
Kogut, Alan J.
2011-01-01
The Primordial Inflation Explorer is an Explorer-class mission to measure the gravity-wave signature of primordial inflation through its distinctive imprint on the linear polarization of the cosmic microwave background. PIXIE uses an innovative optical design to achieve background-limited sensitivity in 400 spectral channels spanning 2.5 decades in frequency from 30 GHz to 6 THz (1 cm to 50 micron wavelength). The principal science goal is the detection and characterization of linear polarization from an inflationary epoch in the early universe, with tensor-to-scalar ratio r < 10A{-3) at 5 standard deviations. The rich PIXIE data set will also constrain physical processes ranging from Big Bang cosmology to the nature of the first stars to physical conditions within the interstellar medium of the Galaxy. I describe the PIXIE instrument and mission architecture needed to detect the inflationary signature using only 4 semiconductor bolometers.
Gravitational wave background and Higgs false vacuum inflation
NASA Astrophysics Data System (ADS)
Masina, Isabella
2014-06-01
For a narrow band of values of the top quark and Higgs boson masses, the standard model Higgs potential develops a shallow local minimum at energies of about 1016 GeV, where primordial inflation could have started in a cold metastable state. For each point of that band, the highness of the Higgs potential at the false minimum is calculable, and there is an associated prediction for the inflationary gravitational wave background, namely, for the tensor to scalar ratio r. We show that the recent measurement of r by the BICEP2 collaboration, r =0.16-0.05+0.06 at 1σ, combined with the most up-to-date measurements of the top quark and Higgs boson masses, reveals that the hypothesis that a standard model shallow false minimum was the source of inflation in the early Universe is viable.
Bounce inflation cosmology with Standard Model Higgs boson
Wan, Youping; Huang, Fa Peng; Zhang, Xinmin; Qiu, Taotao; Cai, Yi-Fu; Li, Hong E-mail: qiutt@mail.ccnu.edu.cn E-mail: yifucai@ustc.edu.cn E-mail: xmzhang@ihep.ac.cn
2015-12-01
It is of great interest to connect cosmology in the early universe to the Standard Model of particle physics. In this paper, we try to construct a bounce inflation model with the standard model Higgs boson, where the one loop correction is taken into account in the effective potential of Higgs field. In this model, a Galileon term has been introduced to eliminate the ghost mode when bounce happens. Moreover, due to the fact that the Fermion loop correction can make part of the Higgs potential negative, one naturally obtains a large equation of state(EoS) parameter in the contracting phase, which can eliminate the anisotropy problem. After the bounce, the model can drive the universe into the standard higgs inflation phase, which can generate nearly scale-invariant power spectrum.
The Cosmic Microwave Background & Inflation, Then & Now
NASA Astrophysics Data System (ADS)
Bond, J. Richard; Contaldi, Carlo; Pogosyan, Dmitry; Mason, Brian; Myers, Steve; Pearson, Tim; Pen, Ue-Li; Prunet, Simon; Readhead, Tony; Sievers, Jonathan
2002-12-01
The most recent results from the Boomerang, Maxima, DASI, CBI and VSA CMB experiments significantly increase the case for accelerated expansion in the early universe (the inflationary paradigm) and at the current epoch (dark energy dominance). This is especially so when combined with data on high redshift supernovae (SN1) and large scale structure (LSS), encoding information from local cluster abundances, galaxy clustering, and gravitational lensing. There are ``7 pillars of Inflation'' that can be shown with the CMB probe, and at least 5, and possibly 6, of these have already been demonstrated in the CMB data: (1) the effects of a large scale gravitational potential, demonstrated with COBE/DMR in 1992-96 (2) acoustic peaks/dips in the angular power spectrum of the radiation, which tell about the geometry of the Universe, with the large first peak convincingly shown with Boomerang and Maxima data in 2000, a multiple peak/dip pattern shown in data from Boomerang and DASI (2nd, 3rd peaks, first and 2nd dips in 2001) and from CBI (2nd, 3rd, 4th, 5th peaks, 3rd, 4th dips at 1-sigma in 2002) (3) damping due to shear viscosity and the width of the region over which hydrogen recombination occurred when the universe was 400000 years old (CBI 2002) (4) the primary anisotropies should have a Gaussian distribution (be maximally random) in almost all inflationary models, the best data on this coming from Boomerang; (5) secondary anisotropies associated with nonlinear phenomena subsequent to 400000 years, which must be there and may have been detected by CBI and another experiment, BIMA. Showing the 5 ``pillars'' involves detailed confrontation of the experimental data with theory; e.g., (5) compares the CBI data with predictions from two of the largest cosmological hydrodynamics simulations ever done. DASI, Boomerang and CBI in 2002, AMiBA in 2003, and many other experiments have the sensitivity to demonstrate the next pillar, (6) polarization, which must be there at the ~ 7
Holographic Probabilities in Eternal Inflation
NASA Astrophysics Data System (ADS)
Bousso, Raphael
2006-11-01
In the global description of eternal inflation, probabilities for vacua are notoriously ambiguous. The local point of view is preferred by holography and naturally picks out a simple probability measure. It is insensitive to large expansion factors or lifetimes and so resolves a recently noted paradox. Any cosmological measure must be complemented with the probability for observers to emerge in a given vacuum. In lieu of anthropic criteria, I propose to estimate this by the entropy that can be produced in a local patch. This allows for prior-free predictions.
Inflation from supersymmetric quantum cosmology
Socorro, J.; D'Oleire, Marco
2010-08-15
We derive a special scalar field potential using the anisotropic Bianchi type I cosmological model from canonical quantum cosmology under determined conditions in the evolution to anisotropic variables {beta}{sub {+-}}. In the process, we obtain a family of potentials that has been introduced by hand in the literature to explain cosmological data. Considering supersymmetric quantum cosmology, this family is scanned, fixing the exponential potential as more viable in the inflation scenario V({phi})=V{sub 0}e{sup -{radical}(3){phi}}.
Foam rigidized inflatable structural assemblies
NASA Technical Reports Server (NTRS)
Tinker, Michael L. (Inventor); Schnell, Andrew R. (Inventor)
2010-01-01
An inflatable and rigidizable structure for use as a habitat or a load bearing structure is disclosed. The structure consists of an outer wall and an inner wall defining a containment member and a bladder. The bladder is pressurized to erect the structure from an initially collapsed state. The containment member is subsequently injected with rigidizable fluid through an arrangement of injection ports. Exhaust gases from the curing rigidizable fluid are vented through an arrangement of exhaust ports. The rate of erection can be controlled by frictional engagement with a container or by using a tether. A method for fabricating a tubular structure is disclosed.
Inflation Adjustments for Defense Acquisition
2014-10-01
Harmon Daniel B. Levine Stanley A. Horowitz, Project Leader INSTITUTE FOR DEFENSE ANALYSES 4850 Mark Center Drive Alexandria, Virginia 22311-1882 Approved...T U T E F O R D E F E N S E A N A L Y S E S IDA Document D-5112 Inflation Adjustments for Defense Acquisition Bruce R. Harmon Daniel B. Levine...might do a better job? The focus of the study is on aircraft procurement. By way of terminology , “cost index,” “price index,” and “deflator” are used
Analysis of Inflatable Rock Bolts
NASA Astrophysics Data System (ADS)
Li, Charlie C.
2016-01-01
An inflatable bolt is integrated in the rock mass through the friction and mechanical interlock at the bolt-rock interface. The pullout resistance of the inflatable bolt is determined by the contact stress at the interface. The contact stress is composed of two parts, termed the primary and secondary contact stresses. The former refers to the stress established during bolt installation and the latter is mobilized when the bolt tends to slip in the borehole owing to the roughness of the borehole surface. The existing analysis of the inflatable rock bolt does not appropriately describe the interaction between the bolt and the rock since the influence of the folded tongue of the bolt on the stiffness of the bolt and the elastic rebound of the bolt tube in the end of bolt installation are ignored. The interaction of the inflatable bolt with the rock is thoroughly analysed by taking into account the elastic displacements of the rock mass and the bolt tube during and after bolt installation in this article. The study aims to reveal the influence of the bolt tongue on the contact stress and the different anchoring mechanisms of the bolt in hard and soft rocks. A new solution to the primary contact stress is derived, which is more realistic than the existing one in describing the interaction between the bolt and the rock. The mechanism of the secondary contact stress is also discussed from the point of view of the mechanical behaviour of the asperities on the borehole surface. The analytical solutions are in agreement with both the laboratory and field pullout test results. The analysis reveals that the primary contact stress decreases with the Young's modulus of the rock mass and increases with the borehole diameter and installation pump pressure. The primary contact stress can be easily established in soft and weak rock but is low or zero in hard and strong rock. In soft and weak rock, the primary contact stress is crucially important for the anchorage of the bolt, while
Distinguishing between extra natural inflation and natural inflation after BICEP2
Kohri, Kazunori; Lim, C.S.; Lin, Chia-Min E-mail: lim@lab.twcu.ac.jp
2014-08-01
In this paper, we carefully calculated the tensor-to-scalar ratio, the running spectral index, and the running of running spectrum for (extra) natural inflation in order to compare with recent BICEP2 data, PLANCK satellite data and future 21 cm data. We discovered that the prediction for running spectral index and the running of running spectrum in natural inflation is different from that in the case of extra natural inflation. Near future observation for the running spectral index can only provide marginal accuracy which may not allow us distinguishing between extra natural inflation from natural inflation clearly unless the experimental accuracy can be further improved.
Inflation Metaphor in Contemporary American English
ERIC Educational Resources Information Center
Hu, Chunyu; Chen, Zhi
2015-01-01
Inflation is often regarded as a dangerous phenomenon which poses a potential threat to economies in the world. It is thus an entity that demands the constant attention of economists, policymakers and the general public. In order to make this abstract entry more concrete and vivid, a number of metaphorical expressions are used to depict inflation.…
Grade Inflation: Magnitude, Causes, and Consequences.
ERIC Educational Resources Information Center
Garten, Edward D.; Olday, David B.
The extent of grade inflation at the college level, possible causes of the phenomenon, and its potential consequences for colleges and universities and the individual student are discussed. Grade inflation since 1965 has been attributed to the following possible causes: grade point averages (GPA) have increased because of real changes in high…
Grade Inflation: An Issue for Higher Education?
ERIC Educational Resources Information Center
Caruth, Donald L.; Caruth, Gail D.
2013-01-01
Grade inflation impacts university credibility, student courses of study, choices of institution, and other areas. There has been an upward shift in grades without a corresponding upward shift in knowledge gained. Some of the most frequently mentioned causes of grade inflation are: (1) student evaluations of professors; (2) student teacher…
Does Competition among Schools Encourage Grade Inflation?
ERIC Educational Resources Information Center
Walsh, Patrick
2010-01-01
This paper considers whether high schools in competitive environments use grade inflation to attract and retain families, perhaps in addition to more constructive responses. Two measures of grade inflation are used: the cutoffs used by each school to assign a letter grade to a percent score and high school grade point average after controlling for…
Demystify Learning Expectations to Address Grade Inflation
ERIC Educational Resources Information Center
Hodges, Linda C.
2014-01-01
This article describes the subject of "grade inflation," a reference to educators giving higher grades to student work than their expectations for student achievement warrant. Of the many reasons why this practice happens, Hodges specifically discusses inflating grades as "a natural consequence" when the faculty really…
Does Competition among Schools Encourage Grade Inflation?
ERIC Educational Resources Information Center
Walsh, Patrick
2010-01-01
This paper considers whether high schools in competitive environments use grade inflation to attract and retain families, perhaps in addition to more constructive responses. Two measures of grade inflation are used: the cutoffs used by each school to assign a letter grade to a percent score; and high school GPA after controlling for test scores, a…
76 FR 56294 - Inflatable Personal Flotation Devices
Federal Register 2010, 2011, 2012, 2013, 2014
2011-09-13
... SECURITY Coast Guard 46 CFR Part 160 RIN 1625-AB60 Inflatable Personal Flotation Devices AGENCY: Coast... flotation devices (PFDs) with current voluntary industry consensus standards, and to slightly modify... rule entitled ``Inflatable Personal Flotation Devices'' in the Federal Register (76 FR 17561)....
Inflation Metaphor in the TIME Magazine Corpus
ERIC Educational Resources Information Center
Hu, Chunyu; Liu, Huijie
2016-01-01
A historical perspective on economy metaphor can shed new lights on economic thoughts. Based on the TIME Magazine Corpus (TMC), this paper investigates inflation metaphor over 83 years and compares findings against the economic data over the relatively corresponding period. The results show how inflation, an abstract concept and a normal economic…
Structural Considerations of Inflatable Reentry Vehicles
NASA Technical Reports Server (NTRS)
Leonard, Robert W.; Brooks, George W.; McComb, Harvey G., Jr.
1960-01-01
The state of the design art for inflated structures applicable to reentry vehicles is discussed. Included are material properties, calculations of buckling and collapse loads, and calculations of deflections and vibration frequencies. A new theory for the analysis of inflated plates is presented and compared with experiment.
Dual-Compartment Inflatable Suitlock
NASA Technical Reports Server (NTRS)
Howe, Scott; Kennedy, Kriss J.; Guirgis, Peggy L.
2012-01-01
A paper discusses a dual-compartment inflatable suitlock (DCIS) for Extra - vehicular Activity (EVA) that will allow for dust control, suit maintenance, and efficient EVA egress/ingress. The expandable (inflatable technologies) aspect of the design will allow the unit to stow in a compact package for transport. The DCIS consists of three hard, in line bulkheads, separating two cylindrical membrane-walled compartments. The inner bulkhead can be fitted with a variety of hatch types, docking flanges, and mating hardware, such as the common berthing mechanism (CBM), for the purpose of mating with vehicles, habitats, and other pressurized modules. The inner bulkhead and center bulkhead function as the end walls of the inner compartment, which, during operations, would stay pressurized, either matching the pressure of the habitat or acting as a lower-pressure transitional volume. The suited crewmember can quickly don a suit, and egress the suitlock without waiting for the compartment to depressurize. The outer compartment can be pressurized infrequently, when a long dwell time is expected prior to the next EVA, or during off-nominal suit maintenance tasks, allowing shirtsleeve inspections and maintenance of the space suits. The outer bulkhead has a pressure-assisted hatch door that stays open and stowed routinely, but can be closed for suit maintenance and pressurization as needed.
The phenomenology of trapped inflation
NASA Astrophysics Data System (ADS)
Pearce, Lauren; Peloso, Marco; Sorbo, Lorenzo
2016-11-01
Trapped inflation is a mechanism in which particle production from the moving inflaton is the main source of friction in the inflaton equation of motion. The produced fields source inflaton perturbations, which dominate over the vacuum ones. We review the computation of the perturbations performed in the original work and in a successive analysis that makes use of the effective field theory (EFT) of inflation. This second paper employs the power spectrum of the inflaton perturbations obtained in the original work, and obtains a bispectrum which parametrically agrees with that of the original work, even if it originates from a different operator. We show that one approximation used in the original work to compute the correlators of the produced quanta is invalid. We replace this approximation with an exact solution of the system of equations developed in the original work and obtain a different amplitude for the power spectrum of the inflaton perturbations, which has a significant consequence for the allowed region of parameter space in this mechanism. We then show that the operator responsible for the bispectrum in the EFT computation does not arise from the computational scheme developed in the original paper and that the agreement between the bispectra of the two works is also caused by the invalid approximation.
Superimposed oscillations in brane inflation
Ávila, Santiago; Martin, Jérôme; Steer, Danièle A. E-mail: jmartin@iap.fr
2014-08-01
In canonical scalar field inflation, the Starobinsky model (with a linear potential but discontinuous slope) is remarkable in that though slow-roll is violated, both the power-spectrum and bi-spectrum can be calculated exactly analytically. The two-point function is characterised by different power on large and small scales, and a burst of small amplitude superimposed oscillations in between. We extend this analysis to Dirac Born Infeld (DBI) inflation, for which generalised slow-roll is violated at the discontinuity and a rapid variation in the speed of sound c{sub S} occurs. In an attempt to characterise the effect of non-linear kinetic terms on the oscillatory features of the primordial power-spectrum, we show that the resulting power spectrum has a shape and features which differ significantly from those of the standard Starobinsky model. In particular, when c{sub S} is small, the power-spectrum now takes very similar scale invariant values on large and small scales, while on intermediate scales it is characterised by much larger amplitude and higher frequency superimposed oscillations. We also show that calculating non-Gaussianities in this model is a complicated but interesting task since all terms in the cubic action now contribute. Investigating whether the superimposed oscillations could fit to the Planck Cosmic Microwave Background (CMB) data (for instance by explaining the large scale Planck anomalies) with, at the same time, small non-Gaussianities remains an intriguing and open possibility.
The CMB modulation from inflation
NASA Astrophysics Data System (ADS)
Lyth, David H.
2013-08-01
Erickcek, Kamionkowski and Carroll proposed in 2008 that the dipole modulation of the CMB could be due to a very large scale perturbation of the field phi causing the primordial curvature perturbation. We repeat their calculation using weaker assumptions and the current data. If phi is the inflaton of any single-field inflation with the attractor behaviour, the asymmetry is almost certainly too small. If instead phi is any curvaton-type field (ie. one with the canonical kinetic term and a negligible effect during inflation) the asymmetry can agree with observation if |fNL| in the equilateral configuration is simeq 10 for k-1 = 1Gpc and lesssim3 for k-1 = 1Mpc. An fNL with these properties can apparently be obtained from the curvaton with an axionic potential. Within any specific curvaton-type model, the function fNL(k1,k2,k3) required to generate the asymmetry would be determined, and could perhaps already be confirmed or ruled out using existing Planck or WMAP data.
Attraction towards an inflection point inflation
Allahverdi, Rouzbeh; Dutta, Bhaskar; Mazumdar, Anupam
2008-09-15
Many models of high-energy physics possess metastable vacua. It is conceivable that the Universe can get trapped in such a false vacuum, irrespective of its origin and prior history, at an earlier stage during its evolution. The ensuing false vacuum inflation results in a cold and empty universe and has a generic graceful exit problem. We show that an inflection point inflation along the flat directions of the minimal supersymmetric standard model (MSSM) can resolve this graceful exit problem by inflating the bubble, which nucleates out of a false vacuum. The important point is that the initial condition for an MSSM inflation can be naturally realized, due to an attractor behavior toward the inflection point. We investigate these issues in detail and also present an example where metastable vacua, hence the false vacuum inflation, can happen within the MSSM.
First-order inflation. [in cosmology
NASA Technical Reports Server (NTRS)
Turner, Michael S.
1992-01-01
I discuss the most recent model of inflation. In first-order inflation the inflationary epoch is associated with a first-order phase transition, with the most likely candidate being GUT symmetry breaking. The transition from the false-vacuum inflationary phase to the true-vacuum radiation-dominated phase proceeds through the nucleation and percolation of true-vacuum bubbles. The first successful and simplest model of first-order inflation, extended inflation, is discussed in some detail: evolution of the cosmic-scale factor, reheating, density perturbations, and the production of gravitational waves both from quantum fluctuations and bubble collisions. Particular attention is paid to the most critical issue in any model of first-order inflation: the requirements on the nucleation rate to ensure a graceful transition from the inflationary phase to the radiation-dominated phase.
Sneutrino hybrid inflation and nonthermal leptogenesis
Antusch, Stefan; Baumann, Jochen P.; Domcke, Valerie F.; Kostka, Philipp M. E-mail: jbaumann@mppmu.mpg.de E-mail: kostka@mppmu.mpg.de
2010-10-01
In sneutrino hybrid inflation the superpartner of one of the right-handed neutrinos involved in the seesaw mechanism plays the role of the inflaton field. It obtains its large mass after the ''waterfall'' phase transition which ends hybrid inflation. After this phase transition the oscillations of the sneutrino inflaton field may dominate the universe and efficiently produce the baryon asymmetry of the universe via nonthermal leptogenesis. We investigate the conditions under which inflation, with primordial perturbations in accordance with the latest WMAP results, as well as successful nonthermal leptogenesis can be realized simultaneously within the sneutrino hybrid inflation scenario. We point out which requirements successful inflation and leptogenesis impose on the seesaw parameters, i.e. on the Yukawa couplings and the mass of the right-handed (s)neutrino, and derive the predictions for the CMB observables in terms of the right-handed (s)neutrino mass and the other relevant model parameters.
Nonthermal gravitino production after large field inflation
NASA Astrophysics Data System (ADS)
Ema, Yohei; Mukaida, Kyohei; Nakayama, Kazunori; Terada, Takahiro
2016-11-01
We revisit the nonthermal gravitino production at the (p)reheating stage after inflation. Particular attention is paid to large field inflation models with a ℤ 2 symmetry, for which the previous perturbative analysis is inapplicable; and inflation models with a stabilizer superfield, which have not been studied non-perturbatively. It is found that in single-superfield inflation models (without the stabilizer field), nonthermal production of the transverse gravitino can be cosmologically problematic while the abundance of the lon-gitudinal gravitino is small enough. In multi-superfield inflation models (with the stabilizer field), production of the transverse and longitudinal gravitinos is significantly suppressed, and they are cosmologically harmless. We also clarify the relation between the background field method used in the preheating context and the standard perturbative decay method to estimate the gravitino abundance.
Aerocapture Inflatable Decelerator for Planetary Entry
NASA Technical Reports Server (NTRS)
Reza, Sajjad; Hund, Richard; Kustas, Frank; Willcockson, William; Songer, Jarvis; Brown, Glen
2007-01-01
Forward Attached Inflatable Decelerators, more commonly known as inflatable aeroshells, provide an effective, cost efficient means of decelerating spacecrafts by using atmospheric drag for aerocapture or planetary entry instead of conventional liquid propulsion deceleration systems. Entry into planetary atmospheres results in significant heating and aerodynamic pressures which stress aeroshell systems to their useful limits. Incorporation of lightweight inflatable decelerator surfaces with increased surface-area footprints provides the opportunity to reduce heat flux and induced temperatures, while increasing the payload mass fraction. Furthermore, inflatable aeroshell decelerators provide the needed deceleration at considerably higher altitudes and Mach numbers when compared with conventional rigid aeroshell entry systems. Inflatable aeroshells also provide for stowage in a compact space, with subsequent deployment of a large-area, lightweight heatshield to survive entry heating. Use of a deployable heatshield decelerator enables an increase in the spacecraft payload mass fraction and may eliminate the need for a spacecraft backshell.
Initial '80s Development of Inflated Antennas
NASA Technical Reports Server (NTRS)
Friese, G. J.; Bilyeu, G. D.; Thomas, M.
1983-01-01
State of the art technology was considered in the definition and documentation of a membrane surface suitable for use in a space reflector system for long durations in orbit. Requirements for a metal foil-plastic laminate structural element were determined and a laboratory model of a rigidized element to test for strength characteristics was constructed. Characteristics of antennas ranging from 10 meters to 1000 meters were determined. The basic antenna configuration studied consists of (1) a thin film reflector, (2) a thin film cone, (3) a self-rigidizing structural torus at the interface of the cone and reflector; and (4) an inflation system. The reflector is metallized and, when inflated, has a parabolic shape. The cone not only completes the enclosure of the inflatant, but also holds the antenna feed at its apex. The torus keeps the inflated cone-reflector from collapsing inward. Laser test equipment determined the accuracy of the inflated paraboloids.
Freivogel, Ben; Hubeny, Veronika E.; Maloney, Alexander; Myers, Rob; Rangamani, Mukund; Shenker, Stephen; /Stanford U., Phys. Dept.
2005-10-07
We study the realization of inflation within the AdS/CFT correspondence. We assume the existence of a string landscape containing at least one stable AdS vacuum and a (nearby) metastable de Sitter state. Standard arguments imply that the bulk physics in the vicinity of the AdS minimum is described by a boundary CFT. We argue that large enough bubbles of the dS phase, including those able to inflate, are described by mixed states in the CFT. Inflating degrees of freedom are traced over and do not appear explicitly in the boundary description. They nevertheless leave a distinct imprint on the mixed state. Analytic continuation allows us, in principle, to recover a large amount of nonperturbatively defined information about the inflating regime. Our work also shows that no scattering process can create an inflating region, even by quantum tunneling, since a pure state can never evolve into a mixed state under unitary evolution.We study the realization of inflation within the AdS/CFT correspondence. We assume the existence of a string landscape containing at least one stable AdS vacuum and a (nearby) metastable de Sitter state. Standard arguments imply that the bulk physics in the vicinity of the AdS minimum is described by a boundary CFT. We argue that large enough bubbles of the dS phase, including those able to inflate, are described by mixed states in the CFT. Inflating degrees of freedom are traced over and do not appear explicitly in the boundary description. They nevertheless leave a distinct imprint on the mixed state. Analytic continuation allows us, in principle, to recover a large amount of nonperturbatively defined information about the inflating regime. Our work also shows that no scattering process can create an inflating region, even by quantum tunneling, since a pure state can never evolve into a mixed state under unitary evolution.
Gravitational wave background from reheating after hybrid inflation
Garcia-Bellido, Juan; Figueroa, Daniel G.; Sastre, Alfonso
2008-02-15
The reheating of the Universe after hybrid inflation proceeds through the nucleation and subsequent collision of large concentrations of energy density in the form of bubblelike structures moving at relativistic speeds. This generates a significant fraction of energy in the form of a stochastic background of gravitational waves, whose time evolution is determined by the successive stages of reheating: First, tachyonic preheating makes the amplitude of gravity waves grow exponentially fast. Second, bubble collisions add a new burst of gravitational radiation. Third, turbulent motions finally sets the end of gravitational waves production. From then on, these waves propagate unimpeded to us. We find that the fraction of energy density today in these primordial gravitational waves could be significant for grand unified theory (GUT)-scale models of inflation, although well beyond the frequency range sensitivity of gravitational wave observatories like LIGO, LISA, or BBO. However, low-scale models could still produce a detectable signal at frequencies accessible to BBO or DECIGO. For comparison, we have also computed the analogous gravitational wave background from some chaotic inflation models and obtained results similar to those found by other groups. The discovery of such a background would open a new observational window into the very early universe, where the details of the process of reheating, i.e. the big bang, could be explored. Moreover, it could also serve in the future as a new experimental tool for testing the inflationary paradigm.
Fast Bayesian inference for slow-roll inflation
NASA Astrophysics Data System (ADS)
Ringeval, Christophe
2014-04-01
We present and discuss a new approach increasing by orders of magnitude the speed of performing Bayesian inference and parameter estimation within the framework of slow-roll inflation. The method relies on the determination of an effective likelihood for inflation which is a function of the primordial amplitude of the scalar perturbations complemented with the necessary number of the so-called Hubble flow functions to reach the desired accuracy. Starting from any cosmological data set, the effective likelihood is obtained by marginalization over the standard cosmological parameters, here viewed as `nuisance' from the early Universe point of view. As being low dimensional, basic machine-learning algorithms can be trained to accurately reproduce its multidimensional shape and then be used as a proxy to perform fast Bayesian inference on the inflationary models. The robustness and accuracy of the method are illustrated using the Planck cosmic microwave background data to perform primordial parameter estimation for the large field models of inflation. In particular, marginalized over all possible reheating history, we find the power index of the potential to verify p < 2.3 at 95 per cent of confidence.
The Primordial Inflation Explorer (PIXIE) Mission
NASA Technical Reports Server (NTRS)
Kogut, Alan J.; Chuss, David T.; Dotson, Jessie L.; Fixsen, Dale J.; Halpern, Mark; Hinshaw, Gary F.; Meyer, Stephan M.; Moseley, S. Harvey; Seiffert, Michael D.; Spergel, David N.; Wollack, Edward J.
2011-01-01
The Primordial Inflation Explorer (PIXIE) is an Explorer-class mission to map the absolute intensity and linear polarization of the cosmic microwave background and diffuse astrophysical foregrounds over the full sky from frequencies 30 GHz to 6 THz (I cm to 50 I-tm wavelength). PIXIE uses a polarizing Michelson interferometer with 2.7 K optics to measure the difference spectrum between two orthogonal linear polarizations from two co-aligned beams. Either input can view either the sky or a temperature-controlled absolute reference blackbody calibrator. The multimoded optics and high etendu provide sensitivity comparable to kilo-pixel focal plane arrays, but with greatly expanded frequency coverage while using only 4 detectors total. PIXIE builds on the highly successful COBEIFIRAS design by adding large-area polarization-sensitive detectors whose fully symmetric optics are maintained in thermal equilibrium with the CMB. The highly symmetric nulled design provides redundant rejection of major sources of systematic uncertainty. The principal science goal is the detection and characterization of linear polarization from an inflationary epoch in the early universe, with tensor-to-scalar ratio r much less than 10(exp -3). PIXIE will also return a rich data set constraining physical processes ranging from Big Bang cosmology, reionization, and large-scale structure to the local interstellar medium. Keywords: cosmic microwave background, polarization, FTS, bolometer
Dual-chamber inflatable oil boom
Blair, R.M.; Tedeschi, E.T.
1993-08-24
An elongated floating material containment boom section is described having a normally vertical ballasted skirt depending from flotation means, and convertible from a flattened collapsed condition to a deployable condition wherein buoyancy chamber means extending along the upper edge of said skirt are inflated to expanded buoyant configuration, including: a gas-impervious sleeve extending along the upper edge of said normally vertical skirt forming a first outer collapsible and inflatable flotation chamber, a first inflation valve connecting the interior of said sleeve with the ambient atmosphere, through which gas under pressure may be introduced into said sleeve to inflate said first buoyant outer flotation chamber, elongated gas-impervious tube means positioned inside said outer flotation chamber and forming second collapsible and inflatable internal flotation bladder chamber means, second inflation valve means connecting the interior of said bladder means through said outer flotation chamber to the ambient atmosphere through which gas under pressure may be introduced into said bladder means to inflate it forming said second flotation chamber means inside said outer flotation chamber.
Nonthermal gravitino production in tribrid inflation
NASA Astrophysics Data System (ADS)
Antusch, Stefan; Dutta, Koushik
2015-10-01
We investigate nonthermal gravitino production after tribrid inflation in supergravity, which is a variant of supersymmetric hybrid inflation where three fields are involved in the inflationary model and where the inflaton field resides in the matter sector of the theory. In contrast to conventional supersymmetric hybrid inflation, where nonthermal gravitino production imposes severe constraints on the inflationary model, we find that the "nonthermal gravitino problem" is generically absent in models of tribrid inflation, mainly due to two effects: (i) With the inflaton in tribrid inflation (after inflation) being lighter than the waterfall field, the latter has a second decay channel with a much larger rate than for the decay into gravitinos. This reduces the branching ratio for the decay of the waterfall field into gravitinos. (ii) The inflaton generically decays later than the waterfall field, and it does not produce gravitinos when it decays. This leads to a dilution of the gravitino population from the decays of the waterfall field. The combination of both effects generically leads to a strongly reduced gravitino production in tribrid inflation.
Primordial anisotropies in gauged hybrid inflation
NASA Astrophysics Data System (ADS)
Akbar Abolhasani, Ali; Emami, Razieh; Firouzjahi, Hassan
2014-05-01
We study primordial anisotropies generated in the model of gauged hybrid inflation in which the complex waterfall field is charged under a U(1)gauge field. Primordial anisotropies are generated either actively during inflation or from inhomogeneities modulating the surface of end of inflation during waterfall transition. We present a consistent δN mechanism to calculate the anisotropic power spectrum and bispectrum. We show that the primordial anisotropies generated at the surface of end of inflation do not depend on the number of e-folds and therefore do not produce dangerously large anisotropies associated with the IR modes. Furthermore, one can find the parameter space that the anisotropies generated from the surface of end of inflation cancel the anisotropies generated during inflation, therefore relaxing the constrains on model parameters imposed from IR anisotropies. We also show that the gauge field fluctuations induce a red-tilted power spectrum so the averaged power spectrum from the gauge field can change the total power spectrum from blue to red. Therefore, hybrid inflation, once gauged under a U(1) field, can be consistent with the cosmological observations.
No-scale ripple inflation revisited
Li, Tianjun; Li, Zhijin; Nanopoulos, Dimitri V. E-mail: lizhijin@physics.tamu.edu
2014-04-01
We revisit the no-scale ripple inflation model, where no-scale supergravity is modified by an additional term for the inflaton field in the Kähler potential. This term not only breaks one SU(N,1) symmetry explicitly, but also plays an important role for inflation. We generalize the superpotential in the no-scale ripple inflation model slightly. There exists a discrete Z{sub 2} symmetry/parity in the scalar potential in general, which can be preserved or violated by the non-canonical nomalized inflaton kinetic term. Thus, there are three inflation paths: one parity invariant path, and the left and right paths for parity violating scenario. We show that the inflations along the parity invariant path and right path are consistent with the Planck results. However, the gavitino mass for the parity invariant path is so large that the inflation results will be invalid if we consider the inflaton supersymmetry breaking soft mass term. Thus, only the inflation along the right path gives the correct and consistent results. Notably, the tensor-to-scalar ratio in such case can be large, with a value around 0.05, which may be probed by the future Planck experiment.
Negative running can prevent eternal inflation
Kinney, William H.; Freese, Katherine E-mail: ktfreese@umich.edu
2015-01-01
Current data from the Planck satellite and the BICEP2 telescope favor, at around the 2 σ level, negative running of the spectral index of curvature perturbations from inflation. We show that for negative running α < 0, the curvature perturbation amplitude has a maximum on scales larger than our current horizon size. A condition for the absence of eternal inflation is that the curvature perturbation amplitude always remain below unity on superhorizon scales. For current bounds on n{sub S} from Planck, this corresponds to an upper bound of the running α < −9 × 10{sup −5}, so that even tiny running of the scalar spectral index is sufficient to prevent eternal inflation from occurring, as long as the running remains negative on scales outside the horizon. In single-field inflation models, negative running is associated with a finite duration of inflation: we show that eternal inflation may not occur even in cases where inflation lasts as long as 10{sup 4} e-folds.
Inflation model selection meets dark radiation
NASA Astrophysics Data System (ADS)
Tram, Thomas; Vallance, Robert; Vennin, Vincent
2017-01-01
We investigate how inflation model selection is affected by the presence of additional free-streaming relativistic degrees of freedom, i.e. dark radiation. We perform a full Bayesian analysis of both inflation parameters and cosmological parameters taking reheating into account self-consistently. We compute the Bayesian evidence for a few representative inflation scenarios in both the standard ΛCDM model and an extension including dark radiation parametrised by its effective number of relativistic species Neff. Using a minimal dataset (Planck low-l polarisation, temperature power spectrum and lensing reconstruction), we find that the observational status of most inflationary models is unchanged. The exceptions are potentials such as power-law inflation that predict large values for the scalar spectral index that can only be realised when Neff is allowed to vary. Adding baryon acoustic oscillations data and the B-mode data from BICEP2/Keck makes power-law inflation disfavoured, while adding local measurements of the Hubble constant H0 makes power-law inflation slightly favoured compared to the best single-field plateau potentials. This illustrates how the dark radiation solution to the H0 tension would have deep consequences for inflation model selection.
Clustering fossils in solid inflation
Akhshik, Mohammad
2015-05-01
In solid inflation the single field non-Gaussianity consistency condition is violated. As a result, the long tenor perturbation induces observable clustering fossils in the form of quadrupole anisotropy in large scale structure power spectrum. In this work we revisit the bispectrum analysis for the scalar-scalar-scalar and tensor-scalar-scalar bispectrum for the general parameter space of solid. We consider the parameter space of the model in which the level of non-Gaussianity generated is consistent with the Planck constraints. Specializing to this allowed range of model parameter we calculate the quadrupole anisotropy induced from the long tensor perturbations on the power spectrum of the scalar perturbations. We argue that the imprints of clustering fossil from primordial gravitational waves on large scale structures can be detected from the future galaxy surveys.
Cosmological Inflation: A Personal Perspective
NASA Technical Reports Server (NTRS)
Kazanas, Demos
2008-01-01
We present a brief review of Cosmological Inflation from the personal perspective of the speaker who almost 30 years ago proposed a way of resolving the problem of Cosmological Horizon by employing certain notions and developments from the field of High Energy Physics. Along with a brief introduction of the Horizon and Flatness problems of standard cosmology, this lecture concentrates on personal reminiscing of the notions and ideas that prevailed and influenced the author's thinking at the time. The lecture then touches upon some more recent developments related to the subject including exact solutions to conformal gravity that provide a first principles emergence of a characteristic acceleration in the universe and concludes with some personal views concerning the direction that the cosmology field has taken in the past couple of decades and certain speculations some notions that may indicate future directions of research.
Supersymmetric Sneutrino-Higgs inflation
NASA Astrophysics Data System (ADS)
Deen, Rehan; Ovrut, Burt A.; Purves, Austin
2016-11-01
It is shown that in the phenomenologically realistic supersymmetric B - L MSSM theory, a linear combination of the neutral, up Higgs field with the third family left- and right-handed sneutrinos can play the role of the cosmological inflaton. Assuming that supersymmetry is softly broken at a mass scale of order 1013 GeV, the potential energy associated with this field allows for 60 e-foldings of inflation with the cosmological parameters being consistent with all Planck2015 data. The theory does not require any non-standard coupling to gravity and the physical fields are all sub-Planckian during the inflationary epoch. It will be shown that there is a "robust" set of initial conditions which, in addition to satisfying the Planck data, simultaneously are consistent with all present LHC phenomenological requirements.
Leptogenesis in Complex Hybrid Inflation
Martinez-Prieto, Carlos
2008-12-04
We study the transference of an initial leptonic charge contained in a complex scalar field (waterfall field) at the end of the inflation to the leptons of the standard model and then convert this leptonic charge in baryonic charge by sphaleron process. The proposal is that this is done trough the decay of the complex scalar field particles into the the right-handed neutrino which in turn decays into the left-handed lepton doublet and the Higgs field of the standard model. It must be analyzed in what environment the transference is done. We propose that the inflaton (the dominant energy density of the universe) decay into ultrarelativistic fermions before the waterfall field particles decay in the right handed-neutrino, leaving a thermalized bath where the transference of the leptonic asymmetry can be achieved.
Conformal frame dependence of inflation
Domènech, Guillem; Sasaki, Misao E-mail: misao@yukawa.kyoto-u.ac.jp
2015-04-01
Physical equivalence between different conformal frames in scalar-tensor theory of gravity is a known fact. However, assuming that matter minimally couples to the metric of a particular frame, which we call the matter Jordan frame, the matter point of view of the universe may vary from frame to frame. Thus, there is a clear distinction between gravitational sector (curvature and scalar field) and matter sector. In this paper, focusing on a simple power-law inflation model in the Einstein frame, two examples are considered; a super-inflationary and a bouncing universe Jordan frames. Then we consider a spectator curvaton minimally coupled to a Jordan frame, and compute its contribution to the curvature perturbation power spectrum. In these specific examples, we find a blue tilt at short scales for the super-inflationary case, and a blue tilt at large scales for the bouncing case.
Inflating with large effective fields
Burgess, C.P.; Cicoli, M.; Quevedo, F.; Williams, M. E-mail: mcicoli@ictp.it E-mail: mwilliams@perimeterinsititute.ca
2014-11-01
We re-examine large scalar fields within effective field theory, in particular focussing on the issues raised by their use in inflationary models (as suggested by BICEP2 to obtain primordial tensor modes). We argue that when the large-field and low-energy regimes coincide the scalar dynamics is most effectively described in terms of an asymptotic large-field expansion whose form can be dictated by approximate symmetries, which also help control the size of quantum corrections. We discuss several possible symmetries that can achieve this, including pseudo-Goldstone inflatons characterized by a coset G/H (based on abelian and non-abelian, compact and non-compact symmetries), as well as symmetries that are intrinsically higher dimensional. Besides the usual trigonometric potentials of Natural Inflation we also find in this way simple large-field power laws (like V ∝ φ{sup 2}) and exponential potentials, V(φ) = ∑{sub k}V{sub x}e{sup −kφ/M}. Both of these can describe the data well and give slow-roll inflation for large fields without the need for a precise balancing of terms in the potential. The exponential potentials achieve large r through the limit |η| || ε and so predict r ≅ (8/3)(1-n{sub s}); consequently n{sub s} ≅ 0.96 gives r ≅ 0.11 but not much larger (and so could be ruled out as measurements on r and n{sub s} improve). We examine the naturalness issues for these models and give simple examples where symmetries protect these forms, using both pseudo-Goldstone inflatons (with non-abelian non-compact shift symmetries following familiar techniques from chiral perturbation theory) and extra-dimensional models.
Dilution of axion dark radiation by thermal inflation
NASA Astrophysics Data System (ADS)
Hattori, Hironori; Kobayashi, Tatsuo; Omoto, Naoya; Seto, Osamu
2015-07-01
Axions in the Peccei-Quinn (PQ) mechanism provide a promising solution to the strong C P problem in the standard model of particle physics. Coherently generated PQ scalar fields could dominate the energy density in the early Universe and decay into relativistic axions, which would conflict with the current dark radiation constraints. We study the possibility that a thermal inflation driven by a U (1 ) gauged Higgs field dilutes such axions. A well-motivated extra gauged U (1 ) would be the local B -L symmetry. We also discuss the implication for the case of U (1 )B-L and an available baryogenesis mechanism in such cosmology.
12 CFR 263.65 - Civil penalty inflation adjustments.
Code of Federal Regulations, 2011 CFR
2011-01-01
... 12 Banks and Banking 3 2011-01-01 2011-01-01 false Civil penalty inflation adjustments. 263.65... Money Penalties § 263.65 Civil penalty inflation adjustments. (a) Inflation adjustments. In accordance with the Federal Civil Penalties Inflation Adjustment Act of 1990 (28 U.S.C. 2461 note), the Board...
12 CFR 263.65 - Civil penalty inflation adjustments.
Code of Federal Regulations, 2010 CFR
2010-01-01
... 12 Banks and Banking 3 2010-01-01 2010-01-01 false Civil penalty inflation adjustments. 263.65... Money Penalties § 263.65 Civil penalty inflation adjustments. (a) Inflation adjustments. In accordance with the Federal Civil Penalties Inflation Adjustment Act of 1990 (28 U.S.C. 2461 note), the Board...
Constraints on small-field axion inflation
NASA Astrophysics Data System (ADS)
Kobayashi, Tatsuo; Oikawa, Akane; Omoto, Naoya; Otsuka, Hajime; Saga, Ikumi
2017-03-01
We study general class of small-field axion inflations, which are the mixture of polynomial and sinusoidal functions suggested by the natural and axion monodromy inflations. The axion decay constants leading to the successful axion inflations are severely constrained in order not to spoil the big bang nucleosynthesis and overproduce the isocurvature perturbation originating from the QCD axion. We in turn find that the cosmologically favorable axion decay constants are typically of order the grand unification scale or the string scale, which is consistent with the prediction of closed-string axions.
Summary of Attached Inflatable Decelerator (AID) Development
NASA Technical Reports Server (NTRS)
1968-01-01
Summary of Attached Inflatable Decelerator (AID) Development. Attached inflatable decelerators (AID) were tested in an environmental chamber, a spin tunnel, and a wind tunnel. Deployment tests were conducted in environmental chamber to examine guided and unguided water alcohol vapor inflation. Subsonic performance tests were conducted in the spin tunnel. The full-scale wind tunnel was used for AID gust and supersonic performance tests. The supersonic tests were conducted at Mach number 3.0 with 12 ounces of fluid and Mach number 2.2 with six ounces of fluid. [Entire movie available on DVD from CASI as Doc ID 20070030992. Contact help@sti.nasa.gov
Accidental Kähler moduli inflation
Maharana, Anshuman; Rummel, Markus; Sumitomo, Yoske E-mail: markus.rummel@physics.ox.ac.uk
2015-09-01
We study a model of accidental inflation in type IIB string theory where inflation occurs near the inflection point of a small Kähler modulus. A racetrack structure helps to alleviate the known concern that string-loop corrections may spoil Kähler Moduli Inflation unless having a significant suppression via the string coupling or a special brane setup. Also, the hierarchy of gauge group ranks required for the separation between moduli stabilization and inflationary dynamics is relaxed. The relaxation becomes more significant when we use the recently proposed D-term generated racetrack model.
Kähler potentials for Planck inflation
Roest, Diederik; Scalisi, Marco; Zavala, Ivonne E-mail: m.scalisi@rug.nl
2013-11-01
We assess which Kähler potentials in supergravity lead to viable single-field inflationary models that are consistent with Planck. We highlight the role of symmetries, such as shift, Heisenberg and supersymmetry, in these constructions. Also the connections to string theory are pointed out. Finally, we discuss a supergravity model for arbitrary inflationary potentials that is suitable for open string inflation and generalise it to the case of closed string inflation. Our model includes the recently discussed supergravity reformulation of the Starobinsky model of inflation as well as an interesting alternative with comparable predictions.
Spacetime Curvature and Higgs Stability after Inflation.
Herranen, M; Markkanen, T; Nurmi, S; Rajantie, A
2015-12-11
We investigate the dynamics of the Higgs field at the end of inflation in the minimal scenario consisting of an inflaton field coupled to the standard model only through the nonminimal gravitational coupling ξ of the Higgs field. Such a coupling is required by renormalization of the standard model in curved space, and in the current scenario also by vacuum stability during high-scale inflation. We find that for ξ≳1, rapidly changing spacetime curvature at the end of inflation leads to significant production of Higgs particles, potentially triggering a transition to a negative-energy Planck scale vacuum state and causing an immediate collapse of the Universe.
Macroeconomic susceptibility, inflation, and aggregate supply
NASA Astrophysics Data System (ADS)
Hawkins, Raymond J.
2017-03-01
We unify aggregate-supply dynamics as a time-dependent susceptibility-mediated relationship between inflation and aggregate economic output. In addition to representing well various observations of inflation-output dynamics this parsimonious formalism provides a straightforward derivation of popular representations of aggregate-supply dynamics and a natural basis for economic-agent expectations as an element of inflation formation. Our formalism also illuminates questions of causality and time-correlation that challenge central banks for whom aggregate-supply dynamics is a key constraint in their goal of achieving macroeconomic stability.
Accidental Kähler moduli inflation
Maharana, Anshuman; Rummel, Markus; Sumitomo, Yoske
2015-09-14
We study a model of accidental inflation in type IIB string theory where inflation occurs near the inflection point of a small Kähler modulus. A racetrack structure helps to alleviate the known concern that string-loop corrections may spoil Kähler Moduli Inflation unless having a significant suppression via the string coupling or a special brane setup. Also, the hierarchy of gauge group ranks required for the separation between moduli stabilization and inflationary dynamics is relaxed. The relaxation becomes more significant when we use the recently proposed D-term generated racetrack model.
Cosmic background radiation anisotropy in an open inflation, cold dark matter cosmogony
NASA Technical Reports Server (NTRS)
Kamionkowski, Marc; Ratra, Bharat; Spergel, David N.; Sugiyama, Naoshi
1994-01-01
We compute the cosmic background radiation anisotropy, produced by energy-density fluctuations generated during an early epoch of inflation, in an open cosmological model based on the cold dark matter scenario. At Omega(sub 0) is approximately 0.3-0.4, the Cosmic Background Explorer (COBE) normalized open model appears to be consistent with most observations.
Remote inflation: hybrid-like inflation without hybrid-type potential
Matsuda, Tomohiro
2009-07-01
A new scenario of hybrid-like inflation is considered without using hybrid-type potential. Radiation raised continuously by a dissipating inflaton field keeps symmetry restoration in a remote sector, and the false-vacuum energy of the remote sector dominates the energy density during inflation. Remote inflation is terminated when the temperature reaches the critical temperature, or when the slow-roll condition is violated. Without introducing a complex form of couplings, inflaton field may either roll-in (like a standard hybrid inflation) or roll-out (like an inverted-hybrid model or quintessential inflation) on arbitrary inflaton potential. Significant signatures of remote inflation can be observed in the spectrum caused by 1. the inhomogeneous phase transition in the remote sector, or; 2. a successive phase transition in the remote sector. Remote inflation can predict strong amplification or suppression of small-scale perturbations without introducing multiple inflation. Since the inflaton may have a run-away potential, it is also possible to identify the inflaton with quintessence, without introducing additional mechanisms. Even if the false-vacuum energy is not dominated by the remote sector, the phase transition in the remote sector is possible during warm inflation, which may cause significant amplification/suppression of the curvature perturbations.
Vapor pressure measured with inflatable plastic bag
NASA Technical Reports Server (NTRS)
1965-01-01
Deflated plastic bag in a vacuum chamber measures initial low vapor pressures of materials. The bag captures the test sample vapors and visual observation of the vapor-inflated bag under increasing external pressures yields pertinent data.
Inflation Rates, Car Devaluation, and Chemical Kinetics
NASA Astrophysics Data System (ADS)
Pogliani, Lionello; Berberan-Santos, Màrio N.
1996-10-01
The inflation rate problem of a modern economy shows quite interesting similarities with chemical kinetics and especially with first-order chemical reactions. In fact, capital devaluation during periods of rather low inflation rates or inflation measured over short periods shows a dynamics formally similar to that followed by first-order chemical reactions and they can thus be treated by the aid of the same mathematical formalism. Deviations from this similarity occurs for higher inflation rates. The dynamics of price devaluation for two different types of car, a compact car and a luxury car, has been followed for seven years long and it has been established that car devaluation is a process that is formally similar to a zeroth-order chemical kinetic process disregarding the type of car, if car devaluation is much faster than money devaluation. In fact, expensive cars devaluate with a faster rate than inexpensive cars.
Rotating mandrel speeds assembly of plastic inflatables
NASA Technical Reports Server (NTRS)
Mac Fadden, J. A.; Stenlund, S. J.; Wendt, A. J.
1966-01-01
Rotating mandrel permits the accurate cutting, forming, and sealing of plastic gores for assembly of an inflatable surface of revolution. The gores remain on the mandrel until the final seam is reached. Tolerances are tightly controlled by the mandrel configuration.
Gravitational waves and large field inflation
NASA Astrophysics Data System (ADS)
Linde, Andrei
2017-02-01
According to the famous Lyth bound, one can confirm large field inflation by finding tensor modes with sufficiently large tensor-to-scalar ratio r. Here we will try to answer two related questions: is it possible to rule out all large field inflationary models by not finding tensor modes with r above some critical value, and what can we say about the scale of inflation by measuring r? However, in order to answer these questions one should distinguish between two different definitions of the large field inflation and three different definitions of the scale of inflation. We will examine these issues using the theory of cosmological α-attractors as a convenient testing ground.
Constraining SUSY GUTs and Inflation with Cosmology
Rocher, Jonathan
2006-11-03
In the framework of Supersymmetric Grand Unified Theories (SUSY GUTs), the universe undergoes a cascade of symmetry breakings, during which topological defects can be formed. We address the question of the probability of cosmic string formation after a phase of hybrid inflation within a large number of models of SUSY GUTs in agreement with particle and cosmological data. We show that cosmic strings are extremely generic and should be used to relate cosmology and high energy physics. This conclusion is employed together with the WMAP CMB data to strongly constrain SUSY hybrid inflation models. F-term and D-term inflation are studied in the SUSY and minimal SUGRA framework. They are both found to agree with data but suffer from fine tuning of their superpotential coupling ({lambda} (less-or-similar sign) 3 x 10-5 or less). Mass scales of inflation are also constrained to be less than M < or approx. 3 x 1015 GeV.
Cosmological perturbations in transient phantom inflation scenarios
NASA Astrophysics Data System (ADS)
Richarte, Martín G.; Kremer, Gilberto M.
2017-01-01
We present a model of inflation where the inflaton is accommodated as a phantom field which exhibits an initial transient pole behavior and then decays into a quintessence field which is responsible for a radiation era. We must stress that the present unified model only deals with a single field and that the transition between the two eras is achieved in a smooth way, so the model does not suffer from the eternal inflation issue. We explore the conditions for the crossing of the phantom divide line within the inflationary era along with the structural stability of several critical points. We study the behavior of the phantom field within the slow-climb approximation along with the necessary conditions to have sufficient inflation. We also examine the model at the level of classical perturbations within the Newtonian gauge and determine the behavior of the gravitational potential, contrast density and perturbed field near the inflation stage and the subsequent radiation era.
Fermion production during and after axion inflation
Adshead, Peter; Sfakianakis, Evangelos I.
2015-11-11
We study derivatively coupled fermions in axion-driven inflation, specifically m{sub ϕ}{sup 2}ϕ{sup 2} and monodromy inflation, and calculate particle production during the inflationary epoch and the post-inflationary axion oscillations. During inflation, the rolling axion acts as an effective chemical potential for helicity which biases the gravitational production of one fermion helicity over the other. This mechanism allows for efficient gravitational production of heavy fermion states that would otherwise be highly suppressed. Following inflation, the axion oscillates and fermions with both helicities are produced as the effective frequency of the fermion field changes non-adiabatically. For certain values of the fermion mass and axion-fermion coupling strength, the two helicity states are produced asymmetrically, resulting in unequal number-densities of left- and right-helicity fermions.
Biodegradable inflatable balloons for tissue separation.
Basu, Arijit; Haim-Zada, Moran; Domb, Abraham J
2016-10-01
Confining radiation to a specific region (during radiation therapy) minimizes damage to surrounding tissues. Biodegradable inflatable balloons (bio-balloons) were developed. The device protects the normal tissues by increasing the gap between radiation source and critical structures. The radiation fades away while passing through the inflated balloon preventing the surrounding tissues from harmful radiation. These bio-balloons have also found clinical use to treat massive rotator cuff tear. This review summarizes the chemistry, engineering, and clinical development of these biomedical devices. These balloons are made of biodegradable polymers folded into the edge of a trocar and inserted between the tissues to be separated, and inflated by normal saline in the site of the application. The inserted balloon protects the tissues from radiation or mechanical stress. They remain inflated on site for two months and are finally eliminated within 12 months.
Effect of inflation on anisotropic cosmologies
Jensen, L.G.; Stein-Schabes, J.A.
1986-03-01
The effects of anisotropic cosmologies on inflation are studied. By properly formulating the field equations it is possible to show that any model that undergoes sufficient inflation will become isotropic on scales greater than the horizon today. Furthermore, we shall show that it takes a very long time for anisotropies to become visible in the observable part of the Universe. It is interesting to note that the time scale will be independent of the Bianchi Model and of the initial anisotropy. 6 refs.
Deployable and Inflatable Fendering Apparatus and Method
2009-09-25
describe various prior art systems that may be related to the above and/or other bumper and fender devices: [0007] United States Patent No. 6,161,494...thereby, re-achieving aerodynamic streamlining of the automotive vehicle. The disadvantage of this apparatus is that the standoff distance is...watercraft with rigid hull that is inflatable and structurally fixed to the hull. The device consists of a first inflatable bumper mounted to the rigid
Realistic inflation models and primordial gravity waves
NASA Astrophysics Data System (ADS)
Rehman, Mansoor Ur
We investigate both supersymmetric and non-supersymmetric realistic models of inflation. In non-supersymmetric models, inflation is successfully realized by employing both Coleman Weinberg and Higgs potentials in GUTs such as SU(5) and SO(10). The quantum smearing of tree level predictions is discussed in the Higgs inflation. These quantum corrections can arise from the inflaton couplings to other particles such as GUT scalars. As a result of including these corrections, a reduction in the tensor-to-scalar ratio r, a canonical measure of gravity waves produced during inflation, is observed. In a simple phi4 chaotic model, we reconsider a non-minimal (xi > 0) gravitationalcoupling of inflaton φ arising from the interaction xi R phi2, where R is the Ricci scalar. In estimating bounds on various inflationaryparameters we also include quantum corrections. We emphasize that while working with high precision observations such as the current Planck satellite experiment we cannot ignore these radiative and gravitational corrections in analyzing the predictions of various inflationary models. In supersymmetric hybrid inflation with minimal Kahler potential, the soft SUSY breaking terms are shown to play an important role in realizing inflation consistent with the latest WMAP data. The SUSY hybrid models which we consider here predict exceedingly small values of r. However, to obtain observable gravity waves the non-minimal Kahler potential turns out to be a necessary ingredient. A realistic model of flipped SU(5) model, which benefits from the absence of topological defects, is considered in the standard SUSY hybrid inflation. We also present a discussion of shifted hybrid inflation in a realistic model of SUSY SU(5) GUT.
Dynamical Baryogenesis in Complex Hybrid Inflation
Delepine, David; Martinez, Carlos; Urena-Lopez, L. Arturo
2008-07-02
We propose a hybrid inflation model with a complex waterfall field which contains an interaction term that breaks the U (1) global symmetry associated to the waterfall field charge. We show that the asymmetric evolution of the real and imaginary parts of the complex field during the phase transition at the end of inflation translates into a charge asymmetry. The latter strongly depends on the vev of the waterfall field, which is well constrained by diverse cosmological observations.
Instrumentation for the Characterization of Inflatable Structures
NASA Technical Reports Server (NTRS)
Swanson, Gregory T.; Cassell, Alan M.; Johnson, R. Keith
2012-01-01
Current entry, descent, and landing technologies are not practical for heavy payloads due to mass and volume constraints dictated by limitations imposed by launch vehicle fairings. Therefore, new technologies are now being explored to provide a mass- and volume-efficient solution for heavy payload capabilities, including Inflatable Aerodynamic Decelerators (IAD) [1]. Consideration of IADs for space applications has prompted the development of instrumentation systems for integration with flexible structures to characterize system response to flight-like environment testing. This development opportunity faces many challenges specific to inflatable structures in extreme environments, including but not limited to physical flexibility, packaging, temperature, structural integration and data acquisition [2]. In the spring of 2012, two large scale Hypersonic Inflatable Aerodynamic Decelerators (HIAD) will be tested in the National Full-Scale Aerodynamics Complex s 40 by 80 wind tunnel at NASA Ames Research Center. The test series will characterize the performance of a 3.0 m and 6.0 m HIAD at various angles of attack and levels of inflation during flight-like loading. To analyze the performance of these inflatable test articles as they undergo aerodynamic loading, many instrumentation systems have been researched and developed. These systems will utilize new experimental sensing systems developed by the HIAD ground test campaign instrumentation team, in addition to traditional wind tunnel sensing techniques in an effort to improve test article characterization and model validation. During the 2012 test series the instrumentation systems will target inflatable aeroshell static and dynamic deformation, structural strap loading, surface pressure distribution, localized skin deflection, and torus inflation pressure. This paper will offer an overview of inflatable structure instrumentation, and provide detail into the design and implementation of the sensors systems that will
Gravitino problem in minimal supergravity inflation
NASA Astrophysics Data System (ADS)
Hasegawa, Fuminori; Mukaida, Kyohei; Nakayama, Kazunori; Terada, Takahiro; Yamada, Yusuke
2017-04-01
We study non-thermal gravitino production in the minimal supergravity inflation. In this minimal model utilizing orthogonal nilpotent superfields, the particle spectrum includes only graviton, gravitino, inflaton, and goldstino. We find that a substantial fraction of the cosmic energy density can be transferred to the longitudinal gravitino due to non-trivial change of its sound speed. This implies either a breakdown of the effective theory after inflation or a serious gravitino problem.
Inflation in maximal gauged supergravities
Kodama, Hideo; Nozawa, Masato
2015-05-18
We discuss the dynamics of multiple scalar fields and the possibility of realistic inflation in the maximal gauged supergravity. In this paper, we address this problem in the framework of recently discovered 1-parameter deformation of SO(4,4) and SO(5,3) dyonic gaugings, for which the base point of the scalar manifold corresponds to an unstable de Sitter critical point. In the gauge-field frame where the embedding tensor takes the value in the sum of the 36 and 36’ representations of SL(8), we present a scheme that allows us to derive an analytic expression for the scalar potential. With the help of this formalism, we derive the full potential and gauge coupling functions in analytic forms for the SO(3)×SO(3)-invariant subsectors of SO(4,4) and SO(5,3) gaugings, and argue that there exist no new critical points in addition to those discovered so far. For the SO(4,4) gauging, we also study the behavior of 6-dimensional scalar fields in this sector near the Dall’Agata-Inverso de Sitter critical point at which the negative eigenvalue of the scalar mass square with the largest modulus goes to zero as the deformation parameter s approaches a critical value s{sub c}. We find that when the deformation parameter s is taken sufficiently close to the critical value, inflation lasts more than 60 e-folds even if the initial point of the inflaton allows an O(0.1) deviation in Planck units from the Dall’Agata-Inverso critical point. It turns out that the spectral index n{sub s} of the curvature perturbation at the time of the 60 e-folding number is always about 0.96 and within the 1σ range n{sub s}=0.9639±0.0047 obtained by Planck, irrespective of the value of the η parameter at the critical saddle point. The tensor-scalar ratio predicted by this model is around 10{sup −3} and is close to the value in the Starobinsky model.
Inflation in the standard cosmological model
NASA Astrophysics Data System (ADS)
Uzan, Jean-Philippe
2015-12-01
The inflationary paradigm is now part of the standard cosmological model as a description of its primordial phase. While its original motivation was to solve the standard problems of the hot big bang model, it was soon understood that it offers a natural theory for the origin of the large-scale structure of the universe. Most models rely on a slow-rolling scalar field and enjoy very generic predictions. Besides, all the matter of the universe is produced by the decay of the inflaton field at the end of inflation during a phase of reheating. These predictions can be (and are) tested from their imprint of the large-scale structure and in particular the cosmic microwave background. Inflation stands as a window in physics where both general relativity and quantum field theory are at work and which can be observationally studied. It connects cosmology with high-energy physics. Today most models are constructed within extensions of the standard model, such as supersymmetry or string theory. Inflation also disrupts our vision of the universe, in particular with the ideas of chaotic inflation and eternal inflation that tend to promote the image of a very inhomogeneous universe with fractal structure on a large scale. This idea is also at the heart of further speculations, such as the multiverse. This introduction summarizes the connections between inflation and the hot big bang model and details the basics of its dynamics and predictions. xml:lang="fr"
Higgs portal valleys, stability and inflation
NASA Astrophysics Data System (ADS)
Ballesteros, Guillermo; Tamarit, Carlos
2015-09-01
The measured values of the Higgs and top quark masses imply that the Standard Model potential is very likely to be unstable at large Higgs values. This is particularly problematic during inflation, which sources large perturbations of the Higgs. The instability could be cured by a threshold effect induced by a scalar with a large vacuum expectation value and directly connected to the Standard Model through a Higgs portal coupling. However, we find that in a minimal model in which the scalar generates inflation, this mechanism does not stabilize the potential because the mass required for inflation is beyond the instability scale. This conclusion does not change if the Higgs has a direct weak coupling to the scalar curvature. On the other hand, if the potential is absolutely stable, successful inflation in agreement with current CMB data can occur along a valley of the potential with a Mexican hat profile. We revisit the stability conditions, independently of inflation, and clarify that the threshold effect cannot work if the Higgs portal coupling is too small. We also show that inflation in a false Higgs vacuum appearing radiatively for a tuned ratio of the Higgs and top masses leads to an amplitude of primordial gravitational waves that is far too high, ruling out this possibility.
Last stand of single small field inflation
NASA Astrophysics Data System (ADS)
Bramante, Joseph; Lehman, Landon; Martin, Adam; Downes, Sean
2014-07-01
By incorporating both the tensor-to-scalar ratio and the measured value of the spectral index, we set a bound on solo small field inflation of Δϕ/mPl≥1.00√r/0.1 . Unlike previous bounds which require monotonic ɛV, |ηV|<1, and 60 e-folds of inflation, the bound remains valid for nonmonotonic ɛV, |ηV|≳1, and for inflation which occurs only over the eight e-folds which have been observed on the cosmic microwave background. The negative value of the spectral index over the observed eight e-folds is what makes the bound strong; we illustrate this by surveying single field models and finding that for r ≳0.1 and eight e-folds of inflation, there is no simple potential which reproduces observed cosmic microwave background perturbations and remains sub-Planckian. Models that are sub-Planckian after eight e-folds must be patched together with a second epoch of inflation that fills out the remaining ˜50 e-folds. This second, post-cosmic microwave background epoch is characterized by extremely small ɛV and therefore an increasing scalar power spectrum. Using the fact that large power can overabundantly produce primordial black holes, we bound the maximum energy level of the second phase of inflation.
Development of Inflatable Entry Systems Technologies
NASA Technical Reports Server (NTRS)
Player, Charles J.; Cheatwood, F. McNeil; Corliss, James
2005-01-01
Achieving the objectives of NASA s Vision for Space Exploration will require the development of new technologies, which will in turn require higher fidelity modeling and analysis techniques, and innovative testing capabilities. Development of entry systems technologies can be especially difficult due to the lack of facilities and resources available to test these new technologies in mission relevant environments. This paper discusses the technology development process to bring inflatable aeroshell technology from Technology Readiness Level 2 (TRL-2) to TRL-7. This paper focuses mainly on two projects: Inflatable Reentry Vehicle Experiment (IRVE), and Inflatable Aeroshell and Thermal Protection System Development (IATD). The objectives of IRVE are to conduct an inflatable aeroshell flight test that demonstrates exoatmospheric deployment and inflation, reentry survivability and stability, and predictable drag performance. IATD will continue the development of the technology by conducting exploration specific trade studies and feeding forward those results into three more flight tests. Through an examination of these projects, and other potential projects, this paper discusses some of the risks, issues, and unexpected benefits associated with the development of inflatable entry systems technology.
Attractor behaviour in ELKO cosmology
Basak, Abhishek; Bhatt, Jitesh R.; Shankaranarayanan, S.; Varma, K.V. Prasantha E-mail: jeet@prl.res.in E-mail: varma@iisertvm.ac.in
2013-04-01
We study the dynamics of ELKO in the context of accelerated phase of our universe. To avoid the fine tuning problem associated with the initial conditions, it is required that the dynamical equations lead to an early-time attractor. In the earlier works, it was shown that the dynamical equations containing ELKO fields do not lead to early-time stable fixed points. In this work, using redefinition of variables, we show that ELKO cosmology admits early-time stable fixed points. More interestingly, we show that ELKO cosmology admit two sets of attractor points corresponding to slow and fast-roll inflation. The fast-roll inflation attractor point is unique for ELKO as it is independent of the form of the potential. We also discuss the plausible choice of interaction terms in these two sets of attractor points and constraints on the coupling constant.
On corpuscular theory of inflation
NASA Astrophysics Data System (ADS)
Berezhiani, Lasha
2017-02-01
In order to go beyond the mean-field approximation, commonly used in the inflationary computations, an identification of the quantum constituents of the inflationary background is made. In particular, the homogeneous scalar field configuration is represented as a Bose-Einstein condensate of the off-shell inflaton degrees of freedom, with mass significantly screened by the gravitational binding energy. The gravitational counterpart of the classical background is considered to be a degenerate state of the off-shell longitudinal gravitons with the frequency of the order of the Hubble scale. As a result, the origin of the density perturbations in the slow-roll regime is identified as an uncertainty in the position of the constituent inflatons. While in the regime of eternal inflation, the scattering of the constituent gravitons becomes the relevant source of the density perturbations. The gravitational waves, on the other hand, originate from the annihilation of the constituent longitudinal gravitons at all energy scales. This results in the quantum depletion of the classical background, leading to the upper bound on the number of e-folds, after which the semi-classical description is expected to break down; this is estimated to be of the order of the entropy of the initial Hubble patch.
Authorship Inflation in Medical Publications.
Tilak, Gaurie; Prasad, Vinay; Jena, Anupam B
2015-01-01
The number of authors per manuscript in peer-reviewed medical journals has increased substantially in the last several decades. Several reasons have been offered to explain this authorship growth, including increased researcher collaboration, honorary authorship driven by increased pressures for funding and promotion, the belief that including senior authors will facilitate publication, and the growing complexity of medical research. It is unknown, however, whether authorship has grown over time due to growing complexity of published academic articles, in which case growth could be warranted, or whether it has grown due to pressures of funding and academic promotion, which have created "authorship inflation." To answer this question, we analyzed data on authorship count, study type, and size of study population for the first 50 original articles published in each decade during 1960-2010 in 3 major medical journals. Within each type of study we considered (eg, randomized trials, observational studies, etc), average authorship rose more than 3-fold during this period. Similar growth persisted after adjustment for changes in study population sizes over time. Our findings suggest that increasing research complexity is an inadequate explanation for authorship growth. Instead, growth in authorship appears inflationary.
An Isocurvature Cold Dark Matter Cosmogony. I. A Worked Example of Evolution through Inflation
NASA Astrophysics Data System (ADS)
Peebles, P. J. E.
1999-01-01
I present a specific worked example of evolution through inflation to the initial conditions for an isocurvature cold dark matter (ICDM) model for structure formation. The model invokes three scalar fields: one that drives power-law inflation, one that survives to become the present-day CDM, and one that gives the CDM field a mass that slowly decreases during inflation and therefore ``tilts'' the primeval mass fluctuation spectrum of the CDM. The functional forms for the potentials and the parameter values that lead to an observationally acceptable model for structure formation do not seem to be out of line with current ideas about the physics of the very early universe. I argue in an accompanying paper that the model offers a not unacceptable fit to main observational constraints.
Resonance Structure of Preheating after multifield inflation with nonminimal couplings (Part 2)
NASA Astrophysics Data System (ADS)
Prescod-Weinstein, Chanda; Decross, Matthew; Kaiser, David; Prabhu, Anirudh; Sfakianakis, Evangelos
2016-03-01
Post-inflation reheating is a critical phase in the history of the cosmos, necessary to connect early-universe inflation to the successes of the standard hot big bang scenario. Reheating falls between two regimes that are well constrained by observations and match the latest observations remarkably well. After reheating, the energy density should include contributions from multiple species of matter, including the Standard Model particles or types of matter that decay into Standard Model particles prior to big-bang nucleosynthesis. Reheating therefore must be a multifield phenomenon. In this talk we continue our investigation of multifield inflation with nonminimal couplings, focusing on the ``preheating'' phase after inflation during which the scalar-field condensate(s) that drove inflation decay resonantly into higher-momentum quanta. Here we present the structure of resonances in this family of models semi-analytically and numerically across wide regions of parameter space. We construct Floquet charts for a wide range of non-minimal couplings. We also compare the resonance structure with the well-known minimally coupled quartic model, showing how the introduction of non-niminal couplings affects the resonance bands.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 46 Shipping 7 2011-10-01 2011-10-01 false Posting placards containing instructions for launching... Inspections § 169.849 Posting placards containing instructions for launching and inflating inflatable... accessible to the ship's company and guests approved placards containing instructions for launching...
Code of Federal Regulations, 2010 CFR
2010-10-01
... 46 Shipping 7 2010-10-01 2010-10-01 false Posting placards containing instructions for launching... Inspections § 169.849 Posting placards containing instructions for launching and inflating inflatable... accessible to the ship's company and guests approved placards containing instructions for launching...
Preheating after small-field inflation
Brax, Philippe; Mariadassou, Sophie
2011-05-15
Whereas preheating after chaotic and hybrid inflation models has been abundantly studied in the literature, preheating in small field inflation models, where the curvature of the inflaton potential is negative during inflation, remains less explored. In these models, a tachyonic instability at the end of inflation leads to a succession of exponentially large increases and decreases of the inflaton fluctuations as the inflaton condensate oscillates around the minimum of its potential. The net effect is a competition between low-momentum modes which grow and decrease significantly, and modes with higher momenta which grow less but also decrease less. We develop an analytical description of this process, which is analogous to the quantum mechanical problem of tunneling through a volcano-shaped potential. Depending on the parameters, preheating may be so efficient that it completes in less than one oscillation of the inflaton condensate. Preheating after small field inflation may also be followed by a long matter-dominated stage before the Universe thermalizes, depending on the energy scale of inflation and the details of the inflaton interactions. Finally, another feature of these models is that the spectrum of the inflaton fluctuations at the end of preheating may be peaked around the Hubble scale. In fact, because preheating starts when the second slow-roll parameter |{eta}| becomes of order unity while the first slow-roll parameter {epsilon} is still much smaller than 1, the Universe is still inflating during preheating and the modes amplified by the initial tachyonic instability leave the Hubble radius. This may lead to an abundant production of primordial black holes and gravitational waves with frequencies today which are naturally small enough to fall into the range accessible by high-sensitivity interferometric experiments.
Comments on SUSY Inflation Models on the Brane
NASA Astrophysics Data System (ADS)
Lee, Lu-Yun; Cheung, Kingman; Lin, Chia-Min
In this paper we consider a class of inflation models on the brane where the dominant part of the inflaton scalar potential does not depend on the inflaton field value during inflation. In particular, we consider supernatural inflation, its hilltop version, A-term inflation, and supersymmetric (SUSY) D- and F-term hybrid inflation on the brane. We show that the parameter space can be broadened, the inflation scale generally can be lowered, and still possible to have the spectral index ns = 0.96.
Dual-Compartment Inflatable Suitlock
NASA Technical Reports Server (NTRS)
Kennedy, Kriss J.; Guirgis, Peggy L.; Boyle, Robert M.
2013-01-01
There is a need for an improvement over current NASA Extravehicular Activity (EVA) technology. The technology must allow the capacity for quicker, more efficient egress/ingress, allow for shirtsleeve suit maintenance, be compact in transport, and be applicable to environments ranging from planetary surface (partial-g) to orbital or deep space zero-g environments. The technology must also be resistant to dust and other foreign contaminants that may be present on or around a planetary surface. The technology should be portable, and be capable of docking with a variety of habitats, ports, stations, vehicles, and other pressurized modules. The Dual-Compartment Inflatable Suitlock (DCIS) consists of three hard inline bulkheads, separating two cylindrical membrane-walled compartments. The Inner Bulkhead can be fitted with a variety of hatch types, docking flanges, and mating hardware, such as the Common Berthing Mechanism (CBM), for the purpose of mating with vehicles, habitats, and other pressurized modules. The Inner Bulkhead and Center Bulkhead function as the end walls of the Inner Compartment, which during operations, would stay pressurized, either matching the pressure of the habitat or acting as a lower-pressure transitional volume. The Inner Compartment contains donning/doffing fixtures and inner suit-port hatches. The Center Bulkhead has two integrated suit-ports along with a maintenance hatch. The Center Bulkhead and Outer Bulkhead function as the end walls of the Outer Compartment, which stays at vacuum during normal operations. This allows the crewmember to quickly don a suit, and egress the suitlock without waiting for the Outer Compartment to depressurize. The Outer Compartment can be pressurized infrequently for both nominal and off-nominal suit maintenance tasks, allowing shirtsleeve inspections and maintenance/repair of the environmental suits. The Outer Bulkhead has a pressure-assisted hatch door that stays open and stowed during EVA operations, but can
New type of hill-top inflation
NASA Astrophysics Data System (ADS)
Barvinsky, A. O.; Kamenshchik, A. Yu.; Nesterov, D. V.
2016-01-01
We suggest a new type of hill-top inflation originating from the initial conditions in the form of the microcanonical density matrix for the cosmological model with a large number of quantum fields conformally coupled to gravity. Initial conditions for inflation are set up by cosmological instantons describing underbarrier oscillations in the vicinity of the inflaton potential maximum. These periodic oscillations of the inflaton field and cosmological scale factor are obtained within the approximation of two coupled oscillators subject to the slow roll regime in the Euclidean time. This regime is characterized by rapid oscillations of the scale factor on the background of a slowly varying inflaton, which guarantees smallness of slow roll parameters epsilon and η of the following inflation stage. A hill-like shape of the inflaton potential is shown to be generated by logarithmic loop corrections to the tree-level asymptotically shift-invariant potential in the non-minimal Higgs inflation model and R2-gravity. The solution to the problem of hierarchy between the Planckian scale and the inflation scale is discussed within the concept of conformal higher spin fields, which also suggests the mechanism bringing the model below the gravitational cutoff and, thus, protecting it from large graviton loop corrections.
Inflation, economic policy, and the inner city
Curtis, L.A.
1981-07-01
This article describes the greater impact of inflation among the poor and minorities in American inner cities than among other population groups. Surveys show, however, that minorities are even more concerned over unemployment and racial discrimination than over inflation. There are indications that, especially today, crime and potential group disorder are affected by or influence inflation, unemployment, and discrimination in the inner city. With these interrelated factors in mind, present federal economic policy is reviewed, critiqued, and interpreted as basically consistent with Keynesian economic theory. Modifications of and alternatives to present policy are offered that fit both inner-city needs and the concerns of the rest of American society. These policies include targeted private sector neighborhood development and self-help, private sector productivity increases through workplace democracy, private-public sector codetermination of investment, private-public sector job guarantees, and public anti-inflation policy carefully targeted at the basic necessities of energy, food, housing, and health care - which have a disproportionate effect on inflation in the inner city, as well as the overall economy. Coalitions are suggested that could politically implement such policies.
Inflation with a constant rate of roll
Motohashi, Hayato; Starobinsky, Alexei A.; Yokoyama, Jun'ichi E-mail: alstar@landau.ac.ru
2015-09-01
We consider an inflationary scenario where the rate of inflaton roll defined by {sup ··}φ/H φ-dot remains constant. The rate of roll is small for slow-roll inflation, while a generic rate of roll leads to the interesting case of 'constant-roll' inflation. We find a general exact solution for the inflaton potential required for such inflaton behaviour. In this model, due to non-slow evolution of background, the would-be decaying mode of linear scalar (curvature) perturbations may not be neglected. It can even grow for some values of the model parameter, while the other mode always remains constant. However, this always occurs for unstable solutions which are not attractors for the given potential. The most interesting particular cases of constant-roll inflation remaining viable with the most recent observational data are quadratic hilltop inflation (with cutoff) and natural inflation (with an additional negative cosmological constant). In these cases even-order slow-roll parameters approach non-negligible constants while the odd ones are asymptotically vanishing in the quasi-de Sitter regime.
Observational constraints on Tachyon and DBI inflation
NASA Astrophysics Data System (ADS)
Li, Sheng; Liddle, Andrew R.
2014-03-01
We present a systematic method for evaluation of perturbation observables in non-canonical single-field inflation models within the slow-roll approximation, which allied with field redefinitions enables predictions to be established for a wide range of models. We use this to investigate various non-canonical inflation models, including Tachyon inflation and DBI inflation. The Lambert Script W function will be used extensively in our method for the evaluation of observables. In the Tachyon case, in the slow-roll approximation the model can be approximated by a canonical field with a redefined potential, which yields predictions in better agreement with observations than the canonical equivalents. For DBI inflation models we consider contributions from both the scalar potential and the warp geometry. In the case of a quartic potential, we find a formula for the observables under both non-relativistic (sound speed cs2 ~ 1) and relativistic behaviour (cs2 ll 1) of the scalar DBI inflaton. For a quadratic potential we find two branches in the non-relativistic cs2 ~ 1 case, determined by the competition of model parameters, while for the relativistic case cs2 → 0, we find consistency with results already in the literature. We present a comparison to the latest Planck satellite observations. Most of the non-canonical models we investigate, including the Tachyon, are better fits to data than canonical models with the same potential, but we find that DBI models in the slow-roll regime have difficulty in matching the data.
Inflation with a constant rate of roll
NASA Astrophysics Data System (ADS)
Motohashi, Hayato; Starobinsky, Alexei A.; Yokoyama, Jun'ichi
2015-09-01
We consider an inflationary scenario where the rate of inflaton roll defined by ̈phi/H dot phi remains constant. The rate of roll is small for slow-roll inflation, while a generic rate of roll leads to the interesting case of 'constant-roll' inflation. We find a general exact solution for the inflaton potential required for such inflaton behaviour. In this model, due to non-slow evolution of background, the would-be decaying mode of linear scalar (curvature) perturbations may not be neglected. It can even grow for some values of the model parameter, while the other mode always remains constant. However, this always occurs for unstable solutions which are not attractors for the given potential. The most interesting particular cases of constant-roll inflation remaining viable with the most recent observational data are quadratic hilltop inflation (with cutoff) and natural inflation (with an additional negative cosmological constant). In these cases even-order slow-roll parameters approach non-negligible constants while the odd ones are asymptotically vanishing in the quasi-de Sitter regime.
Wirelessly Controllable Inflated Electroactive Polymer (EAP) Reflectors
NASA Technical Reports Server (NTRS)
Bao, Xiaoqi; Bar-Cohen, Yoseph; Chang, Zensheu; Sherrit, Stewart; Badescu, Mircea
2005-01-01
Inflatable membrane reflectors are attractive for deployable, large aperture, lightweight optical and microwave systems in micro-gravity space environment. However, any fabrication flaw or temperature variation may results in significant aberration of the surface. Even for a perfectly fabricated inflatable membrane mirror with uniform thickness, theory shows it will form a Hencky curve surface but a desired parabolic or spherical surface. Precision control of the surfaceshape of extremely flexible membrane structures is a critical challenge for the success of this technology. Wirelessly controllable inflated reflectors made of electroactive polymers (EAP) are proposed in this paper. A finite element model was configured to predict the behavior of the inflatable EAP membranes under pre-strains, pressures and distributed electric charges on the surface. To explore the controllability of the inflatable EAP reflectors, an iteration algorism was developed to find the required electric actuation for correcting the aberration of the Hencky curve to the desired parabolic curve. The correction capability of the reflectors with available EAP materials was explored numerically and is presented in this paper.
Reheating the Universe after string theory inflation
Kofman, Lev; Yi, Piljin
2005-11-15
In string theory realizations of inflation, the endpoint of inflation is often brane-antibrane annihilation. We consider the processes of reheating of the standard model universe after brane inflation. We identify the channels of inflaton energy decay, cascading from tachyon annihilation through massive closed string loops, KK modes, and brane displacement moduli to the lighter standard model particles. Cosmological data constrains scenarios by putting stringent limits on the fraction of reheating energy deposited in gravitons and nonstandard sector massive relics. We estimate the energy deposited into various light degrees of freedom in the open and closed string sectors, the timing of reheating, and the reheating temperature. Production of gravitons is significantly suppressed in warped inflation. However, we predict a residual gravitational radiation background at the level {omega}{sub GW}{approx}10{sup -8} of the present cosmological energy density. We also extend our analysis to multiple throat scenarios. A viable reheating would be possible in a single throat or in a certain subclass of multiple throat scenarios of the KKLMMT type inflation model, but overproduction of massive Kaluza-Klein (KK) modes poses a serious problem. The problem is quite severe if some inner manifold comes with approximate isometries (angular KK modes) or if there exists a throat of modest length other than the standard model throat, possibly associated with some hidden sector (low-lying KK modes)
Interest and Inflation Risk: Investor Behavior.
González, María de la O; Jareño, Francisco; Skinner, Frank S
2016-01-01
We examine investor behavior under interest and inflation risk in different scenarios. To that end, we analyze the relation between stock returns and unexpected changes in nominal and real interest rates and inflation for the US stock market. This relation is examined in detail by breaking the results down from the US stock market level to sector, sub-sector, and to individual industries as the ability of different industries to absorb unexpected changes in interest rates and inflation can vary by industry and by contraction and expansion sub-periods. While most significant relations are conventionally negative, some are consistently positive. This suggests some relevant implications on investor behavior. Thus, investments in industries with this positive relation can form a safe haven from unexpected changes in real and nominal interest rates. Gold has an insignificant beta during recessionary conditions hinting that Gold can be a safe haven during recessions. However, Gold also has a consistent negative relation to unexpected changes in inflation thereby damaging the claim that Gold is a hedge against inflation.
Inflection-point B -L Higgs inflation
NASA Astrophysics Data System (ADS)
Okada, Nobuchika; Raut, Digesh
2017-02-01
Inflection-point inflation is an interesting possibility to realize a successful slow-roll inflation when inflation is driven by a single scalar field with its initial value below the Planck mass (ϕI≲MPl). In order for a renormalization group (RG) improved effective λ ϕ4 potential to develop an inflection point, the quartic coupling λ (ϕ ) must exhibit a minimum with an almost vanishing value in its RG evolution, namely λ (ϕI)≃0 and βλ(ϕI)≃0 , where βλ is the beta function of the quartic coupling. As an example, we consider the minimal gauged B -L extended Standard Model at the TeV scale, where we identify the B -L Higgs field as the inflaton field. For a successful inflection-point inflation, which is consistent with the current cosmological observations, the mass ratios among the Z' gauge boson, the right-handed neutrinos and the B -L Higgs boson are fixed. Our scenario can be tested in the future collider experiments such as the high-luminosity LHC and the SHiP experiments. In addition, the inflection-point inflation provides a unique prediction for the running of the spectral index α ≃-2.7 ×10-3(60/N) 2 (N is the e -folding number), which can be tested in the near future.
Hybrid inflation with Planck scale fields
NASA Astrophysics Data System (ADS)
Dine, Michael; Stephenson-Haskins, Laurel
2015-09-01
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 be viewed as generalizations to a large field regime of hybrid inflation. We note close parallels to small and large field axion models. This paper outlines the requirements for successful modular inflation, and gives examples of effective field theories which satisfy them. The required tunings are readily characterized. These models can also be thought of as models of chaotic inflation, in a way we describe. In the modular framework, one would expect that any would-be Peccei-Quinn symmetry would likely be badly broken during inflation, and the axion would have Hubble scale mass; in this situation, isocurvature fluctuations would be suppressed and the initial misalignment angle would be fixed, rather than being a random variable.
New type of hill-top inflation
Barvinsky, A.O.; Kamenshchik, A.Yu.; Nesterov, D.V.
2016-01-20
We suggest a new type of hill-top inflation originating from the initial conditions in the form of the microcanonical density matrix for the cosmological model with a large number of quantum fields conformally coupled to gravity. Initial conditions for inflation are set up by cosmological instantons describing underbarrier oscillations in the vicinity of the inflaton potential maximum. These periodic oscillations of the inflaton field and cosmological scale factor are obtained within the approximation of two coupled oscillators subject to the slow roll regime in the Euclidean time. This regime is characterized by rapid oscillations of the scale factor on the background of a slowly varying inflaton, which guarantees smallness of slow roll parameters ϵ and η of the following inflation stage. A hill-like shape of the inflaton potential is shown to be generated by logarithmic loop corrections to the tree-level asymptotically shift-invariant potential in the non-minimal Higgs inflation model and R{sup 2}-gravity. The solution to the problem of hierarchy between the Planckian scale and the inflation scale is discussed within the concept of conformal higher spin fields, which also suggests the mechanism bringing the model below the gravitational cutoff and, thus, protecting it from large graviton loop corrections.
New type of hill-top inflation
Barvinsky, A.O.; Nesterov, D.V.; Kamenshchik, A.Yu. E-mail: Alexander.Kamenshchik@bo.infn.it
2016-01-01
We suggest a new type of hill-top inflation originating from the initial conditions in the form of the microcanonical density matrix for the cosmological model with a large number of quantum fields conformally coupled to gravity. Initial conditions for inflation are set up by cosmological instantons describing underbarrier oscillations in the vicinity of the inflaton potential maximum. These periodic oscillations of the inflaton field and cosmological scale factor are obtained within the approximation of two coupled oscillators subject to the slow roll regime in the Euclidean time. This regime is characterized by rapid oscillations of the scale factor on the background of a slowly varying inflaton, which guarantees smallness of slow roll parameters ε and η of the following inflation stage. A hill-like shape of the inflaton potential is shown to be generated by logarithmic loop corrections to the tree-level asymptotically shift-invariant potential in the non-minimal Higgs inflation model and R{sup 2}-gravity. The solution to the problem of hierarchy between the Planckian scale and the inflation scale is discussed within the concept of conformal higher spin fields, which also suggests the mechanism bringing the model below the gravitational cutoff and, thus, protecting it from large graviton loop corrections.
Interest and Inflation Risk: Investor Behavior
González, María de la O; Jareño, Francisco; Skinner, Frank S.
2016-01-01
We examine investor behavior under interest and inflation risk in different scenarios. To that end, we analyze the relation between stock returns and unexpected changes in nominal and real interest rates and inflation for the US stock market. This relation is examined in detail by breaking the results down from the US stock market level to sector, sub-sector, and to individual industries as the ability of different industries to absorb unexpected changes in interest rates and inflation can vary by industry and by contraction and expansion sub-periods. While most significant relations are conventionally negative, some are consistently positive. This suggests some relevant implications on investor behavior. Thus, investments in industries with this positive relation can form a safe haven from unexpected changes in real and nominal interest rates. Gold has an insignificant beta during recessionary conditions hinting that Gold can be a safe haven during recessions. However, Gold also has a consistent negative relation to unexpected changes in inflation thereby damaging the claim that Gold is a hedge against inflation. PMID:27047418
NASA Astrophysics Data System (ADS)
Hirano, Shin'ichi; Kobayashi, Tsutomu; Yokoyama, Shuichiro
2016-11-01
The conventional slow-roll approximation is broken in the so-called "ultra slow-roll" models of inflation, for which the inflaton potential is exactly (or extremely) flat. The interesting nature of (canonical) ultra slow-roll inflation is that the curvature perturbation grows on superhorizon scales, but has a scale-invariant power spectrum. We study the ultra slow-roll inflationary dynamics in the presence of noncanonical kinetic terms of the scalar field, namely ultra slow-roll G inflation. We compute the evolution of the curvature perturbation and show that the primordial power spectrum follows a broken power law with an oscillation feature. It is demonstrated that this could explain the lack of large-scale power in the cosmic microwave background temperature anisotropies. We also point out that the violation of the null energy condition is prohibited in ultra slow-roll G inflation, and hence a blue tensor tilt is impossible as long as inflation is driven by the potential. This statement is, however, not true if the energy density is dominated by the kinetic energy of the scalar field.
Origin of density fluctuations in extended inflation
NASA Technical Reports Server (NTRS)
Kolb, Edward W.; Salopek, David S.; Turner, Michael S.
1990-01-01
The density fluctuations (both curvature and isocurvature) that arise due to quantum fluctuations in a simple model of extended inflation based upon the Jordan-Brans-Dicke theory are calculated. Curvature fluctuations arise due to quantum fluctuations in the Brans-Dicke field, in general have a nonscale-invariant spectrum, and can have an amplitude that is cosmologically acceptable and interesting without having to tune any coupling constant to a very small value. The density perturbations that arise due to the inflation field are subdominant. If there are other massless fields in the theory, e.g., an axion or an ilion, then isocurvature fluctuations arise in these fields too. Production of gravitational waves and the massless particles associated with excitations of the Brans-Dicke field are also discussed. Several attempts at more realistic models of extended inflation are also analyzed. The importance of the Einstein conformal frame in calculating curvature fluctuations is emphasized. When viewed in this frame, extended inflation closely resembles slow-rollover inflation with an exponential potential and the usual formula for the amplitude of curvature perturbations applies.
Dissipative Effects in the Effective Field Theory of Inflation
Lopez Nacir, Diana; Porto, Rafael A.; Senatore, Leonardo; Zaldarriaga, Matias; /Princeton, Inst. Advanced Study
2012-09-14
We generalize the effective field theory of single clock inflation to include dissipative effects. Working in unitary gauge we couple a set of composite operators, {Omicron}{sub {mu}{nu}}..., in the effective action which is constrained solely by invariance under time-dependent spatial diffeomorphisms. We restrict ourselves to situations where the degrees of freedom responsible for dissipation do not contribute to the density perturbations at late time. The dynamics of the perturbations is then modified by the appearance of 'friction' and noise terms, and assuming certain locality properties for the Green's functions of these composite operators, we show that there is a regime characterized by a large friction term {gamma} >> H in which the {zeta}-correlators are dominated by the noise and the power spectrum can be significantly enhanced. We also compute the three point function <{zeta}{zeta}{zeta}> for a wide class of models and discuss under which circumstances large friction leads to an increased level of non-Gaussianities. In particular, under our assumptions, we show that strong dissipation together with the required non-linear realization of the symmetries implies |f{sub NL}| {approx} {gamma}/c{sub s}{sup 2} H >> 1. As a paradigmatic example we work out a variation of the 'trapped inflation' scenario with local response functions and perform the matching with our effective theory. A detection of the generic type of signatures that result from incorporating dissipative effects during inflation, as we describe here, would teach us about the dynamics of the early universe and also extend the parameter space of inflationary models.
Cosmological Inflation with Multiple Fields and the Theory of Density Fluctuations
NASA Astrophysics Data System (ADS)
van Tent, B. J. W.
2002-09-01
Inflation is a stage of extremely rapid expansion in the very early universe. It was proposed to solve a number of problems in the standard Big Bang theory. In particular it others an explanation for the origin of structures like (clusters of) galaxies on the one hand (by generating small density fluctuations that act as gravitational seeds), and for the largescale homogeneity of the universe on the other hand (because of the enormous expansion). Inflation is driven by one or more scalar fields with an appropriate potential. In this thesis we develop an analytical formalism to describe the generation of density fluctuations during inflation with multiple scalar fields. We allow these fields to live on a non-trivial (curved) field manifold, as is often the case in high-energy theories. We also treat the evolution of the fluctuations after inflation, until the time of recombination when the cosmic microwave background radiation was formed. Using our formalism observations of the CMBR can then be used to set constraints on the parameters in (multiple-field) inflation models. In more detail this thesis covers the following topics. After introductory chapters on cosmology in general and single-field inflation, the theory of inflation with multiple fields and a general (non-trivial) field metric is derived. In particular we introduce a basis in field space that is induced by the background dynamics and allows a clear distinction between effectively single-field and truly multiple-field effects. The important slow-roll approximation is generalized to the case of multiple fields. Next we derive how scalar and tensor fluctuations are generated from a quantum origin during multiple-field inflation, paying special attention to the transition that occurs when a perturbation mode crosses the Hubble scale. Using some simplifying assumptions the evolution of both adiabatic and isocurvature perturbation modes after inflation is treated. The final results are expressions for the
Axion, μ term, and supersymmetric hybrid inflation
NASA Astrophysics Data System (ADS)
Lazarides, G.; Panagiotakopoulos, C.; Shafi, Q.
2017-03-01
We show how successful supersymmetric hybrid inflation is realized in realistic models where the resolution of the minimal supersymmetric standard model μ problem is intimately linked with axion physics. The scalar fields that accompany the axion, such as the saxion, are closely monitored during and after inflation to ensure that the axion isocurvature perturbations lie below the observational limits. The scalar spectral index ns≃0.96 - 0.97 , while the tensor-to-scalar ratio r , a canonical measure of gravity waves, lies well below the observable range in our example. The axion domain walls are inflated away, and depending on the axion decay constant fa and the magnitude of the μ parameter, the axions and/or the lightest supersymmetric particle compose the dark matter in the Universe. Nonthermal leptogenesis is naturally implemented in this class of models.
Inflation after COBE: Lectures on inflationary cosmology
Turner, M.S. . Enrico Fermi Inst. Fermi National Accelerator Lab., Batavia, IL )
1992-01-01
In these lectures I review the standard hot big-bang cosmology, emphasizing its successes, its shortcomings, and its major challenge-a detailed understanding of the formation of structure in the Universe. I then discuss the motivations for and the fundamentals of inflationary cosmology, particularly emphasizing the quantum origin of metric (density and gravity-wave) perturbations. Inflation addresses the shortcomings of the standard cosmology and provides the initial data'' for structure formation. I conclude by addressing the implications of inflation for structure formation, evaluating the various cold dark matter models in the light of the recent detection of temperature anisotropies in the cosmic background radiation by COBE. In the near term, the study of structure formation offers a powerful probe of inflation, as well as specific inflationary models.
Inflation after COBE: Lectures on inflationary cosmology
Turner, M.S. |
1992-12-31
In these lectures I review the standard hot big-bang cosmology, emphasizing its successes, its shortcomings, and its major challenge-a detailed understanding of the formation of structure in the Universe. I then discuss the motivations for and the fundamentals of inflationary cosmology, particularly emphasizing the quantum origin of metric (density and gravity-wave) perturbations. Inflation addresses the shortcomings of the standard cosmology and provides the ``initial data`` for structure formation. I conclude by addressing the implications of inflation for structure formation, evaluating the various cold dark matter models in the light of the recent detection of temperature anisotropies in the cosmic background radiation by COBE. In the near term, the study of structure formation offers a powerful probe of inflation, as well as specific inflationary models.
Initial conditions and sampling for multifield inflation
Easther, Richard; Price, Layne C. E-mail: lpri691@aucklanduni.ac.nz
2013-07-01
We investigate the initial conditions problem for multifield inflation. In these scenarios the pre-inflationary dynamics can be chaotic, increasing the sensitivity of the onset of inflation to the initial data even in the homogeneous limit. To analyze physically equivalent scenarios we compare initial conditions at fixed energy. This ensures that each trajectory is counted once and only once, since the energy density decreases monotonically. We present a full analysis of hybrid inflation that reveals a greater degree of long range order in the set of ''successful'' initial conditions than was previously apparent. In addition, we explore the effective smoothing scale for the fractal set of successful initial conditions induced by the finite duration of the pre-inflationary phase. The role of the prior information used to specify the initial data is discussed in terms of Bayesian sampling.
The problem with false vacuum Higgs inflation
NASA Astrophysics Data System (ADS)
Fairbairn, Malcolm; Grothaus, Philipp; Hogan, Robert
2014-06-01
We investigate the possibility of using the only known fundamental scalar, the Higgs, as an inflaton with minimal coupling to gravity. The peculiar appearance of a plateau or a false vacuum in the renormalised effective scalar potential suggests that the Higgs might drive inflation. For the case of a false vacuum we use an additional singlet scalar field, motivated by the strong CP problem, and its coupling to the Higgs to lift the barrier allowing for a graceful exit from inflation by mimicking hybrid inflation. We find that this scenario is incompatible with current measurements of the Higgs mass and the QCD coupling constant and conclude that the Higgs can only be the inflaton in more complicated scenarios.
Microscopic origin of volume modulus inflation
Cicoli, Michele; Muia, Francesco; Pedro, Francisco Gil E-mail: muia@bo.infn.it
2015-12-01
High-scale string inflationary models are in well-known tension with low-energy supersymmetry. A promising solution involves models where the inflaton is the volume of the extra dimensions so that the gravitino mass relaxes from large values during inflation to smaller values today. We describe a possible microscopic origin of the scalar potential of volume modulus inflation by exploiting non-perturbative effects, string loop and higher derivative perturbative corrections to the supergravity effective action together with contributions from anti-branes and charged hidden matter fields. We also analyse the relation between the size of the flux superpotential and the position of the late-time minimum and the inflection point around which inflation takes place. We perform a detailed study of the inflationary dynamics for a single modulus and a two moduli case where we also analyse the sensitivity of the cosmological observables on the choice of initial conditions.
Inflation and uplifting with nilpotent superfields
Kallosh, Renata; Linde, Andrei E-mail: alinde@stanford.edu
2015-01-01
Recently it was found that a broad class of existing inflationary models based on supergravity can be significantly simplified if some of the standard, unconstrained chiral superfields are replaced by nilpotent superfields, associated with Volkov-Akulov supersymmetry. The same method allows to simplify the existing models of uplifting of AdS vacua in string theory. In this paper we will show that one can go well beyond simplifying the models that already exist. We will propose a broad class of new models of chaotic inflation based on supergravity with nilpotent superfields, which simultaneously incorporate both inflation and uplifting. They provide a simple unified description of inflation and the present acceleration of the universe in the supergravity context.
Chaotic inflation in higher derivative gravity theories
NASA Astrophysics Data System (ADS)
Myrzakul, Shynaray; Myrzakulov, Ratbay; Sebastiani, Lorenzo
2015-03-01
In this paper, we investigate chaotic inflation from a scalar field subjected to a potential in the framework of -gravity, where we add a correction to Einstein's gravity based on a function of the square of the Ricci scalar , the contraction of the Ricci tensor , and the contraction of the Riemann tensor . The Gauss-Bonnet case is also discussed. We give the general formalism of inflation, deriving the slow-roll parameters, the -fold number, and the spectral indices. Several explicit examples are furnished; namely, we will consider the cases of a massive scalar field and a scalar field with quartic potential and some power-law function of the curvature invariants under investigation in the gravitational action of the theory. A viable approach to inflation according with observations is analyzed.
Beginning inflation in an inhomogeneous universe
East, William E.; Kleban, Matthew; Linde, Andrei; Senatore, Leonardo
2016-09-06
Using numerical solutions of the full Einstein field equations coupled to a scalar inflaton field in 3+1 dimensions, we study the conditions under which a universe that is initially expanding, highly inhomogeneous and dominated by gradient energy can transition to an inflationary period. If the initial scalar field variations are contained within a sufficiently flat region of the inflaton potential, and the universe is spatially flat or open on average, inflation will occur following the dilution of the gradient and kinetic energy due to expansion. This is the case even when the scale of the inhomogeneities is comparable to the initial Hubble length, and overdense regions collapse and form black holes, because underdense regions continue expanding, allowing inflation to eventually begin. This establishes that inflation can arise from highly inhomogeneous initial conditions and solve the horizon and flatness problems, at least as long as the variations in the scalar field do not include values that exceed the inflationary plateau.
Beginning inflation in an inhomogeneous universe
East, William E.; Kleban, Matthew; Linde, Andrei; Senatore, Leonardo
2016-09-06
Using numerical solutions of the full Einstein field equations coupled to a scalar inflaton field in 3+1 dimensions, we study the conditions under which a universe that is initially expanding, highly inhomogeneous and dominated by gradient energy can transition to an inflationary period. If the initial scalar field variations are contained within a sufficiently flat region of the inflaton potential, and the universe is spatially flat or open on average, inflation will occur following the dilution of the gradient and kinetic energy due to expansion. This is the case even when the scale of the inhomogeneities is comparable to the initial Hubble length, and overdense regions collapse and form black holes, because underdense regions continue expanding, allowing inflation to eventually begin. In conclusion, this establishes that inflation can arise from highly inhomogeneous initial conditions and solve the horizon and flatness problems, at least as long as the variations in the scalar field do not include values that exceed the inflationary plateau.
Testing for double inflation with WMAP
Parkinson, David; Tsujikawa, Shinji; Bassett, Bruce A.; Amendola, Luca
2005-03-15
With the WMAP data we can now begin to test realistic models of inflation involving multiple scalar fields. These naturally lead to correlated adiabatic and isocurvature (entropy) perturbations with a running spectral index. We present the first full (9 parameter) likelihood analysis of double inflation with WMAP data and find that despite the extra freedom, supersymmetric hybrid potentials are strongly constrained with less than 7% correlated isocurvature component allowed when standard priors are imposed on the cosomological parameters. As a result we also find that Akaike and Bayesian model selection criteria rather strongly prefer single-field inflation, just as equivalent analysis prefers a cosmological constant over dynamical dark energy in the late universe. It appears that simplicity is the best guide to our universe.
Foam inflated rigidized structures for space applications
NASA Astrophysics Data System (ADS)
Lester, D. M.; Warner, M. J.; Blair, M.
1993-11-01
Large lightweight stowable structures that can be deployed in space without astronaut extra vehicular activity are vital to expanding space exploration and utilization. To meet this challenge Foam Inflated Rigidized (FIR) structures have been developed by Thiokol Corporation on the Air Forces's Gossamer Baggie Torus program. In this paper the development, proof of concept demonstration of an eight foot diameter octagonal torus, and design application of this technology for structural elements to stabilize the solar collector of a solar thermal rocket are discussed. A FIR structure uses foam to inflate and pre-stress a resin impregnated fabric skin. The predeployed foam used was a solvent swelled polymer that foams immediately when exposed to vacuum due to rapid solvent loss. This property allows a very simple deployment mechanism to be used in erecting these structures. Once inflated, the skin resin is cured using the available ultraviolet radiation. By using high strength and stiffness fiber materials a stiff, strong lightweight structure was produced.
First Observational Tests of Eternal Inflation
NASA Astrophysics Data System (ADS)
Feeney, Stephen M.; Johnson, Matthew C.; Mortlock, Daniel J.; Peiris, Hiranya V.
2011-08-01
The eternal inflation scenario predicts that our observable Universe resides inside a single bubble embedded in a vast inflating multiverse. We present the first observational tests of eternal inflation, performing a search for cosmological signatures of collisions with other bubble universes in cosmic microwave background data from the WMAP satellite. We conclude that the WMAP 7-year data do not warrant augmenting the cold dark matter model with a cosmological constant with bubble collisions, constraining the average number of detectable bubble collisions on the full sky N¯s<1.6 at 68% C.L. Data from the Planck satellite can be used to more definitively test the bubble-collision hypothesis.
Brane Inflation: From Superstring to Cosmic Strings
Tye, S.-H. Henry
2004-12-10
Brane inflation, where branes move towards each other in the brane world, has been shown to be quite natural in superstring theory. Inflation ends when branes collide and heat the universe, initiating the hot big bang. Cosmic strings (but not domain walls or monopoles) are copiously produced during the brane collision. Using the COBE data on the temperature anisotropy in the cosmic microwave background, the cosmic string tension {mu} is estimated to be around 10 -6 > G{mu} > 10-11, while the present observational bound is 7 x 10 -7 > G{mu}. This implies that the anisotropy that seeds structure formation comes mostly from inflation, but with a small component (< 10%) from cosmic string effects. This cosmic string effect should be testable in the near future via gravitational lensing, the cosmic microwave background radiation, and/or gravitational wave detectors like LIGO II/VIRGO.
Global embedding of fibre inflation models
NASA Astrophysics Data System (ADS)
Cicoli, Michele; Muia, Francesco; Shukla, Pramod
2016-11-01
We present concrete embeddings of fibre inflation models in globally consistent type IIB Calabi-Yau orientifolds with closed string moduli stabilisation. After performing a systematic search through the existing list of toric Calabi-Yau manifolds, we find several examples that reproduce the minimal setup to embed fibre inflation models. This involves Calabi-Yau manifolds with h 1,1 = 3 which are K3 fibrations over a ℙ1 base with an additional shrinkable rigid divisor. We then provide different consistent choices of the underlying brane set-up which generate a non-perturbative superpotential suitable for moduli stabilisation and string loop corrections with the correct form to drive inflation. For each Calabi-Yau orientifold setting, we also compute the effect of higher derivative contributions and study their influence on the inflationary dynamics.
Inflatable structures for a lunar base
NASA Technical Reports Server (NTRS)
Sadeh, Willy Z.; Criswell, Marvin E.
1995-01-01
The first step in the human expansion into space consists of the construction of a human-tended base on the Moon. Establishment of a lunar base depends upon the development of a structure capable of accomodating human life and activities in a shirt sleeve environment. Design and construction of a structure on the Moon require addressing a host of issues and loads that are not encountered on Earth. A lunar structure is essentially a pressure vessel since the internal pressure is the dominating load. The external pressure is effectively an absolute vacuum and the dead loads from both the material mass and a protective regolith layer are quite small due to low lunar gravity. An inflatable structure made of a thin membrane integrated with an inflated supporting frame is highly efficient in resisting the internal pressure loading and the dead loads. Preliminary design computations for a generic lunar inflatable structure are presented.
Is inflation from unwinding fluxes IIB?
NASA Astrophysics Data System (ADS)
Gautason, Fridrik Freyr; Schillo, Marjorie; Van Riet, Thomas
2017-03-01
In this paper we argue that the mechanism of unwinding inflation is naturally present in warped compactifications of type IIB string theory with local throats. The unwinding of flux is caused by its annihilation against branes. The resulting inflaton potential is linear with periodic modulations. We initiate an analysis of the inflationary dynamics and cosmological observables, which are highly constrained by moduli stabilization. For the simplified model of single-Kähler Calabi-Yau spaces we find that many, though not all of the consistency constraints can be satisfied. Particularly, in this simple model geometric constraints are in tension with obtaining the observed amplitude of the scalar power spectrum. However, we do find 60 efolds of inflation with a trans-Planckian field excursion which offers the hope that slightly more complicated models can lead to a fully consistent explicit construction of large field inflation of this kind.
Microscopic origin of volume modulus inflation
Cicoli, Michele; Muia, Francesco; Pedro, Francisco Gil
2015-12-21
High-scale string inflationary models are in well-known tension with low-energy supersymmetry. A promising solution involves models where the inflaton is the volume of the extra dimensions so that the gravitino mass relaxes from large values during inflation to smaller values today. We describe a possible microscopic origin of the scalar potential of volume modulus inflation by exploiting non-perturbative effects, string loop and higher derivative perturbative corrections to the supergravity effective action together with contributions from anti-branes and charged hidden matter fields. We also analyse the relation between the size of the flux superpotential and the position of the late-time minimum and the inflection point around which inflation takes place. We perform a detailed study of the inflationary dynamics for a single modulus and a two moduli case where we also analyse the sensitivity of the cosmological observables on the choice of initial conditions.
First observational tests of eternal inflation.
Feeney, Stephen M; Johnson, Matthew C; Mortlock, Daniel J; Peiris, Hiranya V
2011-08-12
The eternal inflation scenario predicts that our observable Universe resides inside a single bubble embedded in a vast inflating multiverse. We present the first observational tests of eternal inflation, performing a search for cosmological signatures of collisions with other bubble universes in cosmic microwave background data from the WMAP satellite. We conclude that the WMAP 7-year data do not warrant augmenting the cold dark matter model with a cosmological constant with bubble collisions, constraining the average number of detectable bubble collisions on the full sky N(s) < 1.6 at 68% C.L. Data from the Planck satellite can be used to more definitively test the bubble-collision hypothesis.
The Primordial Inflation Polarization Explorer (PIPER)
NASA Technical Reports Server (NTRS)
Chuss, David T.
2008-01-01
The Primordial Inflation Polarization Explorer (PIPER) is a balloon-borne experiment designed to search for the polarized imprint of gravitational waves from cosmic inflation. The discovery of such a signal would provide direct evidence for inflation, and its characterization would provide a means to explore energy scales orders of magnitude larger than any conceivable particle accelerator. PIPER will consist of two cryogenic telescopes-one for each of the Q and U Stokes parameters. Each will use a variable-delay polarization modulator (VPM) as its first element. This architecture is designed to minimize both T->B and E->B systematics. The detectors will be four 32x40 arrays of BUG detectors, utilizing transition-edge sensors and time-domain multiplexing. Each flight will observe approximately 25% of the sky at a single frequency. Additional flights will increase the frequency coverage.
Extended inflation from higher dimensional theories
NASA Technical Reports Server (NTRS)
Holman, Richard; Kolb, Edward W.; Vadas, Sharon L.; Wang, Yun
1990-01-01
The possibility is considered that higher dimensional theories may, upon reduction to four dimensions, allow extended inflation to occur. Two separate models are analayzed. One is a very simple toy model consisting of higher dimensional gravity coupled to a scalar field whose potential allows for a first-order phase transition. The other is a more sophisticated model incorporating the effects of non-trivial field configurations (monopole, Casimir, and fermion bilinear condensate effects) that yield a non-trivial potential for the radius of the internal space. It was found that extended inflation does not occur in these models. It was also found that the bubble nucleation rate in these theories is time dependent unlike the case in the original version of extended inflation.
46 CFR 197.344 - Inflatable floatation devices.
Code of Federal Regulations, 2014 CFR
2014-10-01
... STANDARDS GENERAL PROVISIONS Commercial Diving Operations Equipment § 197.344 Inflatable floatation devices. An inflatable floatation device for SCUBA diving must— (a) Be capable of maintaining the diver at...
46 CFR 197.344 - Inflatable floatation devices.
Code of Federal Regulations, 2010 CFR
2010-10-01
... STANDARDS GENERAL PROVISIONS Commercial Diving Operations Equipment § 197.344 Inflatable floatation devices. An inflatable floatation device for SCUBA diving must— (a) Be capable of maintaining the diver at...
46 CFR 197.344 - Inflatable floatation devices.
Code of Federal Regulations, 2012 CFR
2012-10-01
... STANDARDS GENERAL PROVISIONS Commercial Diving Operations Equipment § 197.344 Inflatable floatation devices. An inflatable floatation device for SCUBA diving must— (a) Be capable of maintaining the diver at...
46 CFR 197.344 - Inflatable floatation devices.
Code of Federal Regulations, 2011 CFR
2011-10-01
... STANDARDS GENERAL PROVISIONS Commercial Diving Operations Equipment § 197.344 Inflatable floatation devices. An inflatable floatation device for SCUBA diving must— (a) Be capable of maintaining the diver at...
46 CFR 197.344 - Inflatable floatation devices.
Code of Federal Regulations, 2013 CFR
2013-10-01
... STANDARDS GENERAL PROVISIONS Commercial Diving Operations Equipment § 197.344 Inflatable floatation devices. An inflatable floatation device for SCUBA diving must— (a) Be capable of maintaining the diver at...
Primordial features as evidence for inflation
Chen, Xingang
2012-01-01
In the primordial universe, fields with mass much larger than the mass-scale of the event-horizon (such as the Hubble parameter in inflation) exist ubiquitously, and can be excited from time to time and oscillate quickly around their minima. These excitations can induce specific patterns in density perturbations, which record the time dependence of the scale factor of the primordial universe, thus provide direct evidence for the inflation paradigm or its alternatives. Such effects are conventionally averaged out in theoretical and data analyses, but can be accessible for experiments targeting on density perturbations with high multipoles.
Non-canonical inflation coupled to matter
Céspedes, Sebastián; Davis, Anne-Christine E-mail: a.c.davis@damtp.cam.ac.uk
2015-11-01
We compute corrections to the inflationary potential due to conformally coupled non-relativistic matter. We find that under certain conditions of the matter coupling, inflation may be interrupted abruptly. We display this in the superconformal Starobinsky model, where matter is conformally coupled to the Einstein frame metric. These corrections may easily stop inflation provided that there is an initial density of non-relativistic matter. Since these additional heavy degrees of freedom generically occur in higher dimension theories, for example as Kaluza-Klein modes, this effect can arise in multiple scenarios.
Hurdles for recent measures in eternal inflation
Aguirre, Anthony; Johnson, Matthew C; Gratton, Steven
2007-06-15
In recent literature on eternal inflation, a number of measures have been introduced which attempt to assign probabilities to different pocket universes by counting the number of each type of pocket according to a specific procedure. We give an overview of the existing measures, pointing out some interesting connections and generic predictions. For example, pairs of vacua that undergo fast transitions between themselves will be strongly favored. The resultant implications for making predictions in a generic potential landscape are discussed. We also raise a number of issues concerning the types of transitions that observers in eternal inflation are able to experience.
A polynomial f(R) inflation model
Huang, Qing-Guo
2014-02-01
Motivated by the ultraviolet complete theory of quantum gravity, for example the string theory, we investigate a polynomial f(R) inflation model in detail. We calculate the spectral index and tensor-to-scalar ratio in the f(R) inflation model with the form of f(R) = R + (R{sup 2})/6M{sup 2} + (λn)/2n (R{sup n})/(3M{sup 2}){sup n-1}. Compared to Planck 2013, we find that R{sup n} term should be exponentially suppressed, i.e. |λ{sub n}|∼<10{sup −2n+2.6}.
A polynomial f(R) inflation model
Huang, Qing-Guo
2014-02-19
Motivated by the ultraviolet complete theory of quantum gravity, for example the string theory, we investigate a polynomial f(R) inflation model in detail. We calculate the spectral index and tensor-to-scalar ratio in the f(R) inflation model with the form of f(R)=R+((R{sup 2})/(6M{sup 2}))+((λ{sub n})/(2n))((R{sup n})/((3M{sup 2}){sup n−1})). Compared to Planck 2013, we find that R{sup n} term should be exponentially suppressed, i.e. |λ{sub n}|≲10{sup −2n+2.6}.
Inflatable partition for fighting mine fires
Conti, Ronald S.; Lazzara, Charles P.
1995-01-01
The seal is a lightweight, inflatable, bag which may be inflated by a portable air generator and is used to seal a burning mine passage. A collapsible tube-like aperture extends through the seal and allows passage of high expansion foam through the seal in a feed tube. The foam fills the passageway and extinguishes the fire. In other embodiments, the feed tubes incorporate means to prevent collapse of the aperture. In these embodiments a shroud connects the feed tube to a foam generator. This seal allows creation of a high expansion foam fire fighting barrier even in upward sloping passages.
Will Quantum Cosmology Resurrect Chaotic Inflation Model?
NASA Astrophysics Data System (ADS)
Kim, Sang Pyo; Kim, Won
2016-07-01
The single field chaotic inflation model with a monomial power greater than one seems to be ruled out by the recent Planck and WMAP CMB data while Starobinsky model with a higher curvature term seems to be a viable model. Higher curvature terms being originated from quantum fluctuations, we revisit the quantum cosmology of the Wheeler-DeWitt equation for the chaotic inflation model. The semiclassical cosmology emerges from quantum cosmology with fluctuations of spacetimes and matter when the wave function is peaked around the semiclassical trajectory with quantum corrections a la the de Broglie-Bohm pilot theory.
Universality classes for models of inflation
Binétruy, P.; Kiritsis, E.; Mabillard, J.; Pieroni, M.; Rosset, C. E-mail: mpieroni@apc.univ-paris7.fr
2015-04-01
We show that the cosmological evolution of a scalar field in a potential can be obtained from a renormalisation group equation. The slow roll regime of inflation models is understood in this context as the slow evolution close to a fixed point, described by the methods of renormalisation group. This explains in part the universality observed in the predictions of a certain number of inflation models. We illustrate this behavior on a certain number of examples and discuss it in the context of the AdS/CFT correspondence.
Higgs vacuum stability and modified chaotic inflation
NASA Astrophysics Data System (ADS)
Saha, Abhijit Kumar; Sil, Arunansu
2017-02-01
The issue of electroweak vacuum stability is studied in presence of a scalar field which participates in modifying the minimal chaotic inflation model. It is shown that the threshold effect on the Higgs quartic coupling originating from the Higgs-inflaton sector interaction can essentially make the electroweak vacuum stable up to the Planck scale. On the other hand we observe that the new physics parameters in this combined framework are enough to provide deviation from the minimal chaotic inflation predictions so as to keep it consistent with recent observation by Planck 2015.
Anisotropic inflation in Gauss-Bonnet gravity
Lahiri, Sayantani
2016-09-19
We study anisotropic inflation with Gauss-Bonnet correction in presence of a massless vector field. In this scenario, exact anisotropic power-law inflation is realized when the inflaton potential, gauge coupling function and the Gauss-Bonnet coupling are exponential functions. We show that anisotropy becomes proportional to two slow-roll parameters of the theory and hence gets enhanced in presence of quadratic curvature corrections. The stability analysis reveals that anisotropic power-law solutions remain stable over a substantially large parameter region.
Reducing the spectral index in supernatural inflation
NASA Astrophysics Data System (ADS)
Lin, Chia-Min; Cheung, Kingman
2009-04-01
Supernatural inflation is an attractive model based on just a flat direction with soft supersymmetry breaking mass terms in the framework of supersymmetry. The beauty of the model is that it needs no fine-tuning. However, the prediction of the spectral index is ns≳1, in contrast to experimental data. In this paper, we discuss supernatural inflation with the spectral index reduced to ns=0.96 without any fine-tuning, considering the general feature that a flat direction is lifted by a nonrenormalizable term with an A-term.
Pre - big bang inflation requires fine tuning
Turner, Michael S.; Weinberg, Erick J.
1997-10-01
The pre-big-bang cosmology inspired by superstring theories has been suggested as an alternative to slow-roll inflation. We analyze, in both the Jordan and Einstein frames, the effect of spatial curvature on this scenario and show that too much curvature --- of either sign --- reduces the duration of the inflationary era to such an extent that the flatness and horizon problems are not solved. Hence, a fine-tuning of initial conditions is required to obtain enough inflation to solve the cosmological problems.
Tingay, David G; Rajapaksa, Anushi; Zonneveld, C Elroy; Black, Don; Perkins, Elizabeth J; Adler, Andy; Grychtol, Bartłomiej; Lavizzari, Anna; Frerichs, Inéz; Zahra, Valerie A; Davis, Peter G
2016-02-01
Ineffective aeration during the first inflations at birth creates regional aeration and ventilation defects, initiating injurious pathways. This study aimed to compare a sustained first inflation at birth or dynamic end-expiratory supported recruitment during tidal inflations against ventilation without intentional recruitment on gas exchange, lung mechanics, spatiotemporal regional aeration and tidal ventilation, and regional lung injury in preterm lambs. Lambs (127 ± 2 d gestation), instrumented at birth, were ventilated for 60 minutes from birth with either lung-protective positive pressure ventilation (control) or as per control after either an initial 30 seconds of 40 cm H2O sustained inflation (SI) or an initial stepwise end-expiratory pressure recruitment maneuver during tidal inflations (duration 180 s; open lung ventilation [OLV]). At study completion, molecular markers of lung injury were analyzed. The initial use of an OLV maneuver, but not SI, at birth resulted in improved lung compliance, oxygenation, end-expiratory lung volume, and reduced ventilatory needs compared with control, persisting throughout the study. These changes were due to more uniform inter- and intrasubject gravity-dependent spatiotemporal patterns of aeration (measured using electrical impedance tomography). Spatial distribution of tidal ventilation was more stable after either recruitment maneuver. All strategies caused regional lung injury patterns that mirrored associated regional volume states. Irrespective of strategy, spatiotemporal volume loss was consistently associated with up-regulation of early growth response-1 expression. Our results show that mechanical and molecular consequences of lung aeration at birth are not simply related to rapidity of fluid clearance; they are also related to spatiotemporal pressure-volume interactions within the lung during inflation and deflation.
Penalty Inflation Adjustments for Civil Money Penalties. Interim Final Rule.
2016-06-27
In accordance with the Federal Civil Penalties Inflation Adjustment Act of 1990, as amended by the Debt Collection Improvement Act of 1996, and further amended by the Bipartisan Budget Act of 2015, section 701: Federal Civil Penalties Inflation Adjustment Act Improvements Act of 2015, this interim final rule incorporates the penalty inflation adjustments for the civil money penalties contained in the Social Security Act
46 CFR 506.3 - Civil monetary penalty inflation adjustment.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 46 Shipping 9 2010-10-01 2010-10-01 false Civil monetary penalty inflation adjustment. 506.3... PENALTY INFLATION ADJUSTMENT § 506.3 Civil monetary penalty inflation adjustment. The Commission shall... each civil monetary penalty provided by law within the jurisdiction of the Commission by the...
46 CFR 506.3 - Civil monetary penalty inflation adjustment.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 46 Shipping 9 2011-10-01 2011-10-01 false Civil monetary penalty inflation adjustment. 506.3... PENALTY INFLATION ADJUSTMENT § 506.3 Civil monetary penalty inflation adjustment. The Commission shall... each civil monetary penalty provided by law within the jurisdiction of the Commission by the...
32 CFR 269.3 - Civil monetary penalty inflation adjustment.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 32 National Defense 2 2011-07-01 2011-07-01 false Civil monetary penalty inflation adjustment. 269... DEFENSE (CONTINUED) MISCELLANEOUS CIVIL MONETARY PENALTY INFLATION ADJUSTMENT § 269.3 Civil monetary penalty inflation adjustment. The Department shall, not later than 180 days after the enactment of...
Singular inflation from Born-Infeld-f(R) gravity
NASA Astrophysics Data System (ADS)
Elizalde, Emilio; Makarenko, Andrey N.
2016-07-01
Accelerating dynamics from Born-Infeld-f(R) gravity are studied in a simplified conformal approach without matter. Explicit unification of inflation with late-time acceleration is realized within this singular inflation approach, which is similar to Odintsov-Oikonomou singular f(R) inflation. Our model turns out to be consistent with the latest release of Planck data.
21 CFR 868.5750 - Inflatable tracheal tube cuff.
Code of Federal Regulations, 2011 CFR
2011-04-01
... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Inflatable tracheal tube cuff. 868.5750 Section... (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5750 Inflatable tracheal tube cuff. (a) Identification. An inflatable tracheal tube cuff is a device used to provide an airtight...
21 CFR 868.5750 - Inflatable tracheal tube cuff.
Code of Federal Regulations, 2013 CFR
2013-04-01
... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Inflatable tracheal tube cuff. 868.5750 Section... (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5750 Inflatable tracheal tube cuff. (a) Identification. An inflatable tracheal tube cuff is a device used to provide an airtight...
21 CFR 868.5750 - Inflatable tracheal tube cuff.
Code of Federal Regulations, 2014 CFR
2014-04-01
... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Inflatable tracheal tube cuff. 868.5750 Section... (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5750 Inflatable tracheal tube cuff. (a) Identification. An inflatable tracheal tube cuff is a device used to provide an airtight...
21 CFR 868.5750 - Inflatable tracheal tube cuff.
Code of Federal Regulations, 2010 CFR
2010-04-01
... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Inflatable tracheal tube cuff. 868.5750 Section... (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5750 Inflatable tracheal tube cuff. (a) Identification. An inflatable tracheal tube cuff is a device used to provide an airtight...
21 CFR 868.5750 - Inflatable tracheal tube cuff.
Code of Federal Regulations, 2012 CFR
2012-04-01
... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Inflatable tracheal tube cuff. 868.5750 Section... (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5750 Inflatable tracheal tube cuff. (a) Identification. An inflatable tracheal tube cuff is a device used to provide an airtight...
Eternal inflation predicts that time will end
Bousso, Raphael; Freivogel, Ben; Leichenauer, Stefan; Rosenhaus, Vladimir
2011-01-15
Present treatments of eternal inflation regulate infinities by imposing a geometric cutoff. We point out that some matter systems reach the cutoff in finite time. This implies a nonzero probability for a novel type of catastrophe. According to the most successful measure proposals, our galaxy is likely to encounter the cutoff within the next 5x10{sup 9} years.
Global-local duality in eternal inflation
Bousso, Raphael; Yang, I-S.
2009-12-15
We prove that the light-cone time cutoff on the multiverse defines the same probabilities as a causal patch with initial conditions in the longest-lived metastable vacuum. This establishes the equivalence of two measures of eternal inflation which naively appear very different (though both are motivated by holography). The duality can be traced to an underlying geometric relation which we identify.
Connecting Measurement and Architecture: Building an Inflatable
ERIC Educational Resources Information Center
Gray, Elizabeth D.; Tullier-Holly, Denise
2007-01-01
This article describes a joint effort between a mathematics educator and a middle school art teacher who wanted their students to experience first hand how construction works in the real world. It starts with students designing and building scale models for a large inflatable item in which they display their art and extends to building the…
Multi-field inflation and cosmological perturbations
NASA Astrophysics Data System (ADS)
Gong, Jinn-Ouk
We provide a concise review on multi-field inflation and cosmological perturbations. We discuss convenient and physically meaningful bases in terms of which perturbations can be systematically studied. We give formal accounts on the gauge fixing conditions and present the perturbation action in two gauges. We also briefly review nonlinear perturbations.
Higgs-otic inflation and moduli stabilization
NASA Astrophysics Data System (ADS)
Bielleman, Sjoerd; Ibáñez, Luis E.; Pedro, Francisco G.; Valenzuela, Irene; Wieck, Clemens
2017-02-01
We study closed-string moduli stabilization in Higgs-otic inflation in Type IIB orientifold backgrounds with fluxes. In this setup large-field inflation is driven by the vacuum energy of mobile D7-branes. Imaginary selfdual (ISD) three-form fluxes in the background source a μ-term and the necessary monodromy for large field excursions while imaginary anti-selfdual (IASD) three-form fluxes are sourced by non-perturbative contri-butions to the superpotential necessary for moduli stabilization. We analyze Kähler moduli stabilization and backreaction on the inflaton potential in detail. Confirming results in the recent literature, we find that integrating out heavy Kähler moduli leads to a controlled flattening of the inflaton potential. We quantify the flux tuning necessary for stability even during large-field inflation. Moreover, we study the backreaction of supersymmetrically stabilized complex structure moduli and the axio-dilaton in the Kähler metric of the inflaton. Contrary to previous findings, this backreaction can be pushed far out in field space if a similar flux tuning as in the Kähler sector is possible. This allows for a trans-Planckian field range large enough to support inflation.
Jettison system for a large inflatable antenna
NASA Technical Reports Server (NTRS)
Jarosz, Don; Hendricks, Steven; Landis, Dave; Tooley, Craig; Martins, Greg
1996-01-01
This paper describes a jettison system used to separate a large, inflatable-deployable antenna from a free-flying spacecraft. The jettison system consists of four discrete Marman band clamps, released simultaneously via pyrotechnics. The design, analysis, analytical simulation, and testing of the system are discussed. Of particular note is the correlation of test results with the Marman band design calculations.
The Impact of Inflation on Endowment Assets
ERIC Educational Resources Information Center
Birkeland, Kathryn; Carr, David L.; Lavin, Angeline M.
2013-01-01
Maintaining spending power in real terms (current) while preserving an endowment's value in real terms (future) is the crux of intergenerational equity. Tobin's (1974) model provides the conceptual basis on which simulations were developed to study the impact of various inflation (0%, TIPS, CPI, HECA, and HEPI) and new giving scenarios ($0, $4…
Grade Inflation: An Elementary and Secondary Perspective
ERIC Educational Resources Information Center
Sraiheen, Abdulwahab; Lesisko, Lee James
2006-01-01
School administrators in a small suburban school district in Southeastern Pennsylvania were concerned about grade inflation at the elementary and secondary levels. Specifically, they wanted to know if students in grades 5, 8, and 11 who scored at the basic or below basic performance level on the 2003-2004 Pennsylvania System of School Assessment…
Grade Inflation: Academic Standards in Higher Education
ERIC Educational Resources Information Center
Hunt, Lester H., Ed.
2008-01-01
This book provides a provocative look at the issues and controversies surrounding grade inflation, and, more generally, grading practices in American higher education. The contributors confront the issues from a number of different disciplines and varying points of view. Topics explored include empirical evidence for and against the claim that…
Grade Inflation and Law School Admissions
ERIC Educational Resources Information Center
Wongsurawat, Winai
2008-01-01
Purpose: The purpose of this paper is to evaluate the evidence on whether grade inflation has led to an increasing emphasis on standardized test scores as a criterion for law school admissions. Design/methodology/approach: Fit probabilistic models to admissions data for American law schools during the mid to late 1990s, a period during which…
Constraints on single-field inflation
Pirtskhalava, David; Santoni, Luca; Trincherini, Enrico
2016-06-28
Many alternatives to canonical slow-roll inflation have been proposed over the years, one of the main motivations being to have a model, capable of generating observable values of non-Gaussianity. In this work, we (re-)explore the physical implications of a great majority of such models within a single, effective field theory framework (including novel models with large non-Gaussianity discussed for the first time below). The constraints we apply — both theoretical and experimental — are found to be rather robust, determined to a great extent by just three parameters: the coefficients of the quadratic EFT operators (δN){sup 2} and δNδE, and the slow-roll parameter ε. This allows to significantly limit the majority of single-field alternatives to canonical slow-roll inflation. While the existing data still leaves some room for most of the considered models, the situation would change dramatically if the current upper limit on the tensor-to-scalar ratio decreased down to r<10{sup −2}. Apart from inflationary models driven by plateau-like potentials, the single-field model that would have a chance of surviving this bound is the recently proposed slow-roll inflation with weakly-broken galileon symmetry. In contrast to canonical slow-roll inflation, the latter model can support r<10{sup −2} even if driven by a convex potential, as well as generate observable values for the amplitude of non-Gaussianity.
Inflatable habitation for the lunar base
NASA Technical Reports Server (NTRS)
Roberts, M.
1992-01-01
Inflatable structures have a number of advantages over rigid modules in providing habitation at a lunar base. Some of these advantages are packaging efficiency, convenience of expansion, flexibility, and psychological benefit to the inhabitants. The relatively small, rigid cylinders fitted to the payload compartment of a launch vehicle are not as efficient volumetrically as a collapsible structure that fits into the same space when packaged, but when deployed is much larger. Pressurized volume is a valuable resource. By providing that resource efficiently, in large units, labor intensive external expansion (such as adding additional modules to the existing base) can be minimized. The expansive interior in an inflatable would facilitate rearrangement of the interior to suite the evolving needs of the base. This large, continuous volume would also relieve claustrophobia, enhancing habitability and improving morale. The purpose of this paper is to explore some of the aspects of inflatable habitat design, including structural, architectural, and environmental considerations. As a specific case, the conceptual design of an inflatable lunar habitat, developed for the Lunar Base Systems Study at the Johnson Space Center, is described.
Self-Inflatable/Self-Rigidizable Reflectarray Antenna
NASA Technical Reports Server (NTRS)
Fang, Houfei; Lou, Michael; Huang, John
2004-01-01
A report describes recent progress in a continuing effort to develop large reflectarray antennas to be deployed in space. Major underlying concepts were reported in two prior NASA Tech Briefs articles: Inflatable Reflectarray Antennas (NPO- 20433), Vol. 23, No. 10 (October 1999), page 50 and Tape-Spring Reinforcements for Inflatable Structural Tubes (NPO-20615), Vol. 24, No. 7 (July 2000), page 58. To recapitulate: An antenna as proposed would include a reflectarray membrane stretched flat on a frame of multiple tubular booms that would be deployed by inflation. The instant report discusses design concepts and relevant basic mechanical principles. Among the concepts are alternative configurations of booms for holding the reflectarray membrane and its radio-frequency feed horn and the use of catenaries and constant-force springs to stretch the reflectarray membrane on the frame at the required tension. Some emphasis is placed on the need to keep the deployed frame rigid without depending on maintenance of inflation in the presence of impinging micrometeors that could cause leaks: for this purpose, the booms could be made as spring-tape-reinforced aluminum laminate tubes like those described in the second-mentioned prior article.
Constraints on single-field inflation
NASA Astrophysics Data System (ADS)
Pirtskhalava, David; Santoni, Luca; Trincherini, Enrico
2016-06-01
Many alternatives to canonical slow-roll inflation have been proposed over the years, one of the main motivations being to have a model, capable of generating observable values of non-Gaussianity. In this work, we (re-)explore the physical implications of a great majority of such models within a single, effective field theory framework (including novel models with large non-Gaussianity discussed for the first time below). The constraints we apply—both theoretical and experimental—are found to be rather robust, determined to a great extent by just three parameters: the coefficients of the quadratic EFT operators (δN)2 and δNδE, and the slow-roll parameter ɛ. This allows to significantly limit the majority of single-field alternatives to canonical slow-roll inflation. While the existing data still leaves some room for most of the considered models, the situation would change dramatically if the current upper limit on the tensor-to-scalar ratio decreased down to r < 10-2. Apart from inflationary models driven by plateau-like potentials, the single-field model that would have a chance of surviving this bound is the recently proposed slow-roll inflation with weakly-broken galileon symmetry. In contrast to canonical slow-roll inflation, the latter model can support r < 10-2 even if driven by a convex potential, as well as generate observable values for the amplitude of non-Gaussianity.
Higgs Boson Mass, New Physics and Inflation
Shafi, Qaisar
2008-05-13
Finding the Standard Model scalar (Higgs) boson is arguably the single most important mission of the LHC. I review predictions for the Higgs boson mass based on stability and perturbativity arguments, taking into account neutrino oscillations. Other topics that are briefly discussed include the CMSSM, extra dimensions, higher dimensional orbifold GUTS, and primordial inflation based on the Coleman-Weinberg potential.
Sneutrino Inflation with α-attractors
Kallosh, Renata; Linde, Andrei; Roest, Diederik; Wrase, Timm
2016-11-22
Sneutrino inflation employs the fermionic partners of the inflaton and stabilizer field as right-handed neutrinos to realize the seesaw mechanism for light neutrino masses. We show that one can improve the latest version of this scenario and its consistency with the Planck data by embedding it in the theory of cosmological α-attractors.
Financial Results during Periods of Inflation.
ERIC Educational Resources Information Center
Thompson, James W.; Anderson, Richard E.
1983-01-01
The effects of inflation on the operations of 10 northeastern colleges and universities and the effect of using current cost accounting are considered. The focus is on adjustments to assets in the plant fund by restating the surplus and deficit calculations of four state and six private institutions. The 10 institutions had plant assets with an…
Inflation, string theory and cosmic strings
NASA Astrophysics Data System (ADS)
Chernoff, David F.; Tye, S.-H. Henry
2015-02-01
At its very beginning, the universe is believed to have grown exponentially in size via the mechanism of inflation. The almost scale-invariant density perturbation spectrum predicted by inflation is strongly supported by cosmological observations, in particular the cosmic microwave background (MB) radiation. However, the universe's precise inflationary scenario remains a profound problem for cosmology and for fundamental physics. String theory, the most-studied theory as the final physical theory of nature, should provide an answer to this question. Some of the proposals on how inflation is realized in string theory are reviewed. Since everything is made of strings, some string loops of cosmological sizes are likely to survive in the hot big bang that followed inflation. They appear as cosmic strings, which can have intricate properties. Because of the warped geometry in flux compactification of the extra spatial dimensions in string theory, some of the cosmic strings may have tensions substantially below the Planck or string scale. Such strings cluster in a manner similar to dark matter leading to hugely enhanced densities. As a result, numerous fossil remnants of the low tension cosmic strings may exist within the galaxy. They can be revealed through the optical lensing of background stars in the near future and studied in detail through gravitational wave emission. We anticipate that these cosmic strings will permit us to address central questions about the properties of string theory as well as the birth of our universe.
The Relationship between Inflation and Defense Expenditures.
1979-12-01
All Federal Expenditures .. ......... . 22 2. Defense Expenditures .... ........... 24 3. Suggested Research on the Impact of DoD Spending ...only major study specifically simulating changes in military spending implied that defense and non- defense expenditures have identical impacts upon...analyzed in Chapter I is that defense expenditures are not assigned a central role in generating inflation. Even when defense spending is incorporated
A simple, approximate model of parachute inflation
Macha, J.M.
1992-01-01
A simple, approximate model of parachute inflation is described. The model is based on the traditional, practical treatment of the fluid resistance of rigid bodies in nonsteady flow, with appropriate extensions to accommodate the change in canopy inflated shape. Correlations for the steady drag and steady radial force as functions of the inflated radius are required as input to the dynamic model. In a novel approach, the radial force is expressed in terms of easily obtainable drag and reefing fine tension measurements. A series of wind tunnel experiments provides the needed correlations. Coefficients associated with the added mass of fluid are evaluated by calibrating the model against an extensive and reliable set of flight data. A parameter is introduced which appears to universally govern the strong dependence of the axial added mass coefficient on motion history. Through comparisons with flight data, the model is shown to realistically predict inflation forces for ribbon and ringslot canopies over a wide range of sizes and deployment conditions.
A simple, approximate model of parachute inflation
Macha, J.M.
1992-11-01
A simple, approximate model of parachute inflation is described. The model is based on the traditional, practical treatment of the fluid resistance of rigid bodies in nonsteady flow, with appropriate extensions to accommodate the change in canopy inflated shape. Correlations for the steady drag and steady radial force as functions of the inflated radius are required as input to the dynamic model. In a novel approach, the radial force is expressed in terms of easily obtainable drag and reefing fine tension measurements. A series of wind tunnel experiments provides the needed correlations. Coefficients associated with the added mass of fluid are evaluated by calibrating the model against an extensive and reliable set of flight data. A parameter is introduced which appears to universally govern the strong dependence of the axial added mass coefficient on motion history. Through comparisons with flight data, the model is shown to realistically predict inflation forces for ribbon and ringslot canopies over a wide range of sizes and deployment conditions.
What's the Best Yardstick to Measure Inflation?
ERIC Educational Resources Information Center
Griswold, John S., Jr.
2006-01-01
This article examines the Higher Education Price Index (HEPI), an inflation index that is useful to trustees. It is the only one of its kind that is designed specifically for higher education and is a more accurate and custom-tailored indicator of cost changes for colleges and universities than the federally compiled Consumer Price Index (CPI).…
Inflation model constraints from data released in 2015
NASA Astrophysics Data System (ADS)
Huang, Qing-Guo; Wang, Ke; Wang, Sai
2016-05-01
We provide the latest constraints on the power spectra of both scalar and tensor perturbations from the cosmic microwave background data (including Planck 2015, BICEP2, and Keck Array experiments) and the new baryon acoustic oscillation scales from SDSS-III BOSS observations. We find that the inflation model with a convex potential is not favored and both the inflation model with a monomial potential and the natural inflation model are marginally disfavored at around 95% confidence level. But both the brane inflation model and the Starobinsky inflation model fit the data quite well.
Natural inflation: consistency with cosmic microwave background observations of Planck and BICEP2
Freese, Katherine; Kinney, William H. E-mail: whkinney@buffalo.edu
2015-03-01
Natural inflation is a good fit to all cosmic microwave background (CMB) data and may be the correct description of an early inflationary expansion of the Universe. The large angular scale CMB polarization experiment BICEP2 has announced a major discovery, which can be explained as the gravitational wave signature of inflation, at a level that matches predictions by natural inflation models. The natural inflation (NI) potential is theoretically exceptionally well motivated in that it is naturally flat due to shift symmetries, and in the simplest version takes the form V(φ) = Λ{sup 4} [1 ± cos(Nφ/f)]. A tensor-to-scalar ratio r > 0.1 as seen by BICEP2 requires the height of any inflationary potential to be comparable to the scale of grand unification and the width to be comparable to the Planck scale. The Cosine Natural Inflation model agrees with all cosmic microwave background measurements as long as f ≥ m{sub Pl} (where m{sub Pl} = 1.22 × 10{sup 19} GeV) and Λ ∼ m{sub GUT} ∼ 10{sup 16} GeV. This paper also discusses other variants of the natural inflation scenario: we show that axion monodromy with potential V∝ φ{sup 2/3} is inconsistent with the BICEP2 limits at the 95% confidence level, and low-scale inflation is strongly ruled out. Linear potentials V ∝ φ are inconsistent with the BICEP2 limit at the 95% confidence level, but are marginally consistent with a joint Planck/BICEP2 limit at 95%. We discuss the pseudo-Nambu Goldstone model proposed by Kinney and Mahanthappa as a concrete realization of low-scale inflation. While the low-scale limit of the model is inconsistent with the data, the large-field limit of the model is marginally consistent with BICEP2. All of the models considered predict negligible running of the scalar spectral index, and would be ruled out by a detection of running.
Observational constraints on Tachyon and DBI inflation
Li, Sheng; Liddle, Andrew R. E-mail: arl@roe.ac.uk
2014-03-01
We present a systematic method for evaluation of perturbation observables in non-canonical single-field inflation models within the slow-roll approximation, which allied with field redefinitions enables predictions to be established for a wide range of models. We use this to investigate various non-canonical inflation models, including Tachyon inflation and DBI inflation. The Lambert W function will be used extensively in our method for the evaluation of observables. In the Tachyon case, in the slow-roll approximation the model can be approximated by a canonical field with a redefined potential, which yields predictions in better agreement with observations than the canonical equivalents. For DBI inflation models we consider contributions from both the scalar potential and the warp geometry. In the case of a quartic potential, we find a formula for the observables under both non-relativistic (sound speed c{sub s}{sup 2} ∼ 1) and relativistic behaviour (c{sub s}{sup 2} || 1) of the scalar DBI inflaton. For a quadratic potential we find two branches in the non-relativistic c{sub s}{sup 2} ∼ 1 case, determined by the competition of model parameters, while for the relativistic case c{sub s}{sup 2} → 0, we find consistency with results already in the literature. We present a comparison to the latest Planck satellite observations. Most of the non-canonical models we investigate, including the Tachyon, are better fits to data than canonical models with the same potential, but we find that DBI models in the slow-roll regime have difficulty in matching the data.
Prospects for primordial gravitational waves in string inflation
NASA Astrophysics Data System (ADS)
Parameswaran, Susha L.; Zavala, Ivonne
2016-08-01
Assuming that the early universe had (i) a description using perturbative string theory and its field theory limit, (ii) an epoch of slow-roll inflation within a four-dimensional effective field theory and a hierarchy of scales Minf < mkk < ms ≲ MPl that keeps the latter under control, we derive an upper bound on the amplitude of primordial gravitational waves. The bound is very sensitive to mild changes in numerical coefficients and the expansion parameters. For example, allowing couplings and mass-squared hierarchies ≲ 0.2 implies r ≲ 0.05, but asking more safely for hierarchies ≲ 0.1, the bound becomes r ≲ 10-6. Moreover, large volumes — typically used in string models to keep backreaction and moduli stabilization under control — drive r down. Consequently, any detection of inflationary gravitational waves would present an interesting but difficult challenge for string theory.
All puffed out: do pufferfish hold their breath while inflated?
McGee, Georgia Evelyn; Clark, Timothy Darren
2014-01-01
The inflation response of pufferfishes is one of the most iconic predator defence strategies in nature. Current dogma suggests that pufferfish inflation represents a breath-holding response, whereby gill oxygen uptake ceases for the duration of inflation and cutaneous respiration increases to compensate. Here, we show that the black-saddled pufferfish (Canthigaster valentini) has an excellent capacity for oxygen uptake while inflated, with uptake rates increasing to five-times that of resting levels. Moreover, we show that this species has negligible capacity for cutaneous respiration, concluding that the gills are the primary site of oxygen uptake while inflated. Despite this, post-deflation recovery of aerobic metabolism took an average of 5.6 h, suggesting a contribution of anaerobic metabolism during pre-inflation activity and during the act of ingesting water to achieve inflation. PMID:25472941
Viable mimetic completion of unified inflation-dark energy evolution in modified gravity
NASA Astrophysics Data System (ADS)
Nojiri, S.; Odintsov, S. D.; Oikonomou, V. K.
2016-11-01
In this paper, we demonstrate that a unified description of early and late-time acceleration is possible in the context of mimetic F (R ) gravity. We study the inflationary era in detail and demonstrate that it can be realized even in mimetic F (R ) gravity where traditional F (R ) gravity fails to describe the inflation. By using standard methods we calculated the spectral index of primordial curvature perturbations and the scalar-to-tensor ratio. We use two F (R ) gravity models and as it turns out, for both the models under study the observational indices are compatible with both the latest Planck and the BICEP2/Keck array data. However, this is only true under some model-dependent fine-tuning, which constrains the models we study. Finally, the graceful exit from inflation issue is addressed, and as we show, the curvature perturbations may trigger the graceful exit from inflation when the slow-roll era ends. However, fine-tuning is needed in order to produce enough inflation by the end of the slow-roll era.
Antigravity suit inflation: kidney function and cardiovascular and hormonal responses in men.
Geelen, G; Kravik, S E; Hadj-Aissa, A; Leftheriotis, G; Vincent, M; Bizollon, C A; Sem-Jacobsen, C W; Greenleaf, J E; Gharib, C
1989-02-01
To investigate the effects of lower body positive pressure (LBPP) on kidney function while controlling certain cardiovascular and endocrine responses, seven men [35 +/- 2 (SE) yr] underwent 30 min of sitting and then 4.5 h of 70 degrees head-up tilt. An antigravity suit was applied (60 Torr legs, 30 Torr abdomen) during the last 3 h of tilt. A similar noninflation experiment was conducted where the suited subjects were tilted for 3.5 h. To provide adequate urine flow, the subjects were hydrated during the course of both experiments. Immediately after inflation, mean arterial pressure increased by 8 +/- 3 Torr and pulse rate decreased by 16 +/- 3 beats/min. Plasma renin activity and aldosterone were maximally suppressed (P less than 0.05) after 2.5 h of inflation. Plasma vasopressin decreased by 40-50% (P less than 0.05) and plasma sodium and potassium remained unchanged during both experiments. Glomerular filtration rate was not increased significantly by inflation, whereas inflation induced marked increases (P less than 0.05) in effective renal plasma flow (ERPF), urine flow, osmolar and free water clearances, and total and fractional sodium excretion. No such changes occurred during control. Thus, LBPP induces 1) a significant increase in ERPF and 2) significant changes in kidney excretory patterns similar to those observed during water immersion or the early phase of bed rest, situations that also result in central vascular volume expansion.
Inflation from nilpotent Kähler corrections
McDonough, Evan; Scalisi, Marco
2016-11-11
We develop a new class of supergravity cosmological models where inflation is induced by terms in the Kähler potential which mix a nilpotent superfield S with a chiral sector Φ. As the new terms are non-(anti)holomorphic, and hence cannot be removed by a Kähler transformation, these models are intrinsically Kähler potential driven. Such terms could arise for example due to a backreaction of an anti-D3 brane on the string theory bulk geometry. We show that this mechanism is very general and allows for a unified description of inflation and dark energy, with controllable SUSY breaking at the vacuum. When the internal geometry of the bulk field is hyperbolic, we prove that small perturbative Kähler corrections naturally lead to α-attractor behaviour, with inflationary predictions in excellent agreement with the latest Planck data.
Seeded hot dark matter models with inflation
NASA Technical Reports Server (NTRS)
Gratsias, John; Scherrer, Robert J.; Steigman, Gary; Villumsen, Jens V.
1993-01-01
We examine massive neutrino (hot dark matter) models for large-scale structure in which the density perturbations are produced by randomly distributed relic seeds and by inflation. Power spectra, streaming velocities, and the Sachs-Wolfe quadrupole fluctuation are derived for this model. We find that the pure seeded hot dark matter model without inflation produces Sachs-Wolfe fluctuations far smaller than those seen by COBE. With the addition of inflationary perturbations, fluctuations consistent with COBE can be produced. The COBE results set the normalization of the inflationary component, which determines the large-scale (about 50/h Mpc) streaming velocities. The normalization of the seed power spectrum is a free parameter, which can be adjusted to obtain the desired fluctuations on small scales. The power spectra produced are very similar to those seen in mixed hot and cold dark matter models.
Generically large nongaussianity in small multifield inflation
Bramante, Joseph
2015-07-07
If forthcoming measurements of cosmic photon polarization restrict the primordial tensor-to-scalar ratio to r<0.01, small field inflation will be a principal candidate for the origin of the universe. Here we show that small multifield inflation, without the hybrid mechanism, typically results in large squeezed nongaussianity. Small multifield potentials contain multiple flat field directions, often identified with the gauge invariant field directions in supersymmetric potentials. We find that unless these field directions have equal slopes, large nongaussianity arises. After identifying relevant differences between large and small two-field potentials, we demonstrate that the latter naturally fulfill the Byrnes-Choi-Hall large nongaussianity conditions. Computations of the primordial power spectrum, spectral index, and squeezed bispectrum, reveal that small two-field models which otherwise match observed primordial perturbations, produce excludably large nongaussianity if the inflatons’ field directions have unequal slopes.
Boost breaking in the EFT of inflation
NASA Astrophysics Data System (ADS)
Delacrétaz, Luca V.; Noumi, Toshifumi; Senatore, Leonardo
2017-02-01
If time-translations are spontaneously broken, so are boosts. This symmetry breaking pattern can be non-linearly realized by either just the Goldstone boson of time translations, or by four Goldstone bosons associated with time translations and boosts. In this paper we extend the Effective Field Theory of Multifield Inflation to consider the case in which the additional Goldstone bosons associated with boosts are light and coupled to the Goldstone boson of time translations. The symmetry breaking pattern forces a coupling to curvature so that the mass of the additional Goldstone bosons is predicted to be equal to √2H in the vast majority of the parameter space where they are light. This pattern therefore offers a natural way of generating self-interacting particles with Hubble mass during inflation. After constructing the general effective Lagrangian, we study how these particles mix and interact with the curvature fluctuations, generating potentially detectable non-Gaussian signals.
Research on inflatable structure for space use
NASA Astrophysics Data System (ADS)
Katou, Sumio; Muragishi, Osamu; Oota, Toyoyuki; Natori, Michihiro; Miura, Kouryou; Sakamaki, Masamori
1993-03-01
This report describes an overview of the trial manufacture and research related to the feasibility of the concepts of a reflector structure using inflatable elements, inflatable tube, and recommendations on experiments on the exposed facility of the JEM (Japanese Experiment Module). The expected roles of and basic structure concept concerning the configurations, dimensions, and film surface materials of the reflector are outlined. The results of the film pressure deformation test, film element hardening test, and film and supporting truss interface test are described. The strength, trial manufacture, and its results are outlined. The onboard JEM experiment concept concerning the research on the earth, preliminary experiment, and on-orbit experiment onboard JEM are introduced.
Gravitational wave consistency relations for multifield inflation.
Price, Layne C; Peiris, Hiranya V; Frazer, Jonathan; Easther, Richard
2015-01-23
We study the tensor spectral index n(t) and the tensor-to-scalar ratio r in the simplest multifield extension to single-field, slow-roll inflation models. We show that multifield models with potentials V∼[under ∑]iλ_{i}|ϕ_{i}|^{p} have different predictions for n(t)/r than single-field models, even when all the couplings are equal λ_{i}=λ_{j}, due to the probabilistic nature of the fields' initial values. We analyze well-motivated prior probabilities for the λ_{i} and initial conditions to make detailed predictions for the marginalized probability distribution of n(t)/r. With O(100) fields and p>3/4, we find that n(t)/r differs from the single-field result of n(t)/r=-1/8 at the 5σ level. This gives a novel and testable prediction for the simplest multifield inflation models.
Gravitational Waves from Oscillons after Inflation
NASA Astrophysics Data System (ADS)
Antusch, Stefan; Cefalà, Francesco; Orani, Stefano
2017-01-01
We investigate the production of gravitational waves during preheating after inflation in the common case of field potentials that are asymmetric around the minimum. In particular, we study the impact of oscillons, comparatively long lived and spatially localized regions where a scalar field (e.g., the inflaton) oscillates with large amplitude. Contrary to a previous study, which considered a symmetric potential, we find that oscillons in asymmetric potentials associated with a phase transition can generate a pronounced peak in the spectrum of gravitational waves that largely exceeds the linear preheating spectrum. We discuss the possible implications of this enhanced amplitude of gravitational waves. For instance, for low scale inflation models, the contribution from the oscillons can strongly enhance the observation prospects at current and future gravitational wave detectors.
Phenomenological approaches of inflation and their equivalence
NASA Astrophysics Data System (ADS)
Boubekeur, Lotfi; Giusarma, Elena; Mena, Olga; Ramírez, Héctor
2015-04-01
In this work, we analyze two possible alternative and model-independent approaches to describe the inflationary period. The first one assumes a general equation of state during inflation due to Mukhanov, while the second one is based on the slow-roll hierarchy suggested by Hoffman and Turner. We find that, remarkably, the two approaches are equivalent from the observational viewpoint, as they single out the same areas in the parameter space, and agree with the inflationary attractors where successful inflation occurs. Rephrased in terms of the familiar picture of a slowly rolling, canonically normalized scalar field, the resulting inflaton excursions in these two approaches are almost identical. Furthermore, once the Galactic dust polarization data from Planck are included in the numerical fits, inflaton excursions can safely take sub-Planckian values.
Dark energy, inflation, and extra dimensions
Steinhardt, Paul J.; Wesley, Daniel
2009-05-15
We consider how accelerated expansion, whether due to inflation or dark energy, imposes strong constraints on fundamental theories obtained by compactification from higher dimensions. For theories that obey the null energy condition (NEC), we find that inflationary cosmology is impossible for a wide range of compactifications; and a dark energy phase consistent with observations is only possible if both Newton's gravitational constant and the dark energy equation of state vary with time. If the theory violates the NEC, inflation and dark energy are only possible if the NEC-violating elements are inhomogeneously distributed in the compact dimensions and vary with time in precise synchrony with the matter and energy density in the noncompact dimensions. Although our proofs are derived assuming general relativity applies in both four and higher dimensions and certain forms of metrics, we argue that similar constraints must apply for more general compactifications.
A dark energy view of inflation
Ilic, Stephane; Kunz, Martin; Liddle, Andrew R.; Frieman, Joshua A.; /Fermilab /Chicago U.
2010-02-01
Traditionally, inflationary models are analyzed in terms of parameters such as the scalar spectral index n{sub s} and the tensor to scalar ratio r, while dark energy models are studied in terms of the equation of state parameter w. Motivated by the fact that both deal with periods of accelerated expansion, we study the evolution of w during inflation, in order to derive observational constraints on its value during an earlier epoch likely dominated by a dynamic form of dark energy. We find that the cosmic microwave background and large-scale structure data is consistent with w{sub inflation} = -1 and provides an upper limit of 1 + w {le} 0.02. Nonetheless, an exact de Sitter expansion with a constant w = -1 is disfavored since this would result in n{sub s} = 1.
BICEP2 in corpuscular description of inflation
Dvali, G.; Gomez, C.
2015-03-15
A corpuscular quantum description of inflation shows that there is no fundamental problem with trans-Planckian excursions of the inflaton field up to about 100 Planck masses, with the upper bound coming from the corpuscular quantum effects. In this description, the r parameter measures the ratio of occupation numbers of gravitons versus inflatons, which, according to BICEP2, was roughly a half at the time of 60 e-foldings prior to the end of inflation. We stress that in a non-Wilsonian UV self-completion of gravity, any trans-Planckian mode coupled to the inflaton is a black hole. Unlike the Wilsonian case, integrating them out gives an exponentially suppressed effect and is unable to prevent trans-Planckian excursions of the inflaton field.
Bounds on tensor wave and twisted inflation
Panda, Sudhakar; Sami, M.; Ward, John
2010-11-15
We study the bounds on tensor wave in a class of twisted inflation models, where D(4+2k)-branes are wrapped on cycles in the compact manifold and wrap the Kaluza-Klein direction in the corresponding effective field theory. While the lower bound is found to be analogous to that in type IIB models of brane inflation, the upper bound turns out to be significantly different. This is argued for a range of values for the parameter g{sub s}M satisfying the self-consistency relation and the WMAP data. Further, we observe that the wrapped D8-brane appears to be the most attractive from a cosmological perspective.
Relic gravitational waves and extended inflation
NASA Technical Reports Server (NTRS)
Turner, Michael S.; Wilczek, Frank
1990-01-01
In extended inflation, a new version of inflation where the transition from the false-vacuum phase to a radiation-dominated Universe is accomplished by bubble nucleation and percolation, bubble collisions supply a potent-and potentially detectable-source of gravitational waves. The present energy density in relic gravity waves from bubble collisions is expected to be about 10(exp -5) of closure density-many orders of magnitude greater than that of the gravity waves produced by quantum fluctuations. Their characteristic wavelength depends upon the reheating temperature T(sub RH): lambda is approximately 10(exp 4) cm (10(exp 14) GeV/T(sub RH)). If large numbers of black holes are produced, a not implausible outcome, they will evaporate producing comparable amounts of shorter wavelength waves, lambda is approximately 10(exp -6) cm (T(sub RH)/10(exp 14) GeV).
Fluctuations along supersymmetric flat directions during inflation
NASA Astrophysics Data System (ADS)
Enqvist, Kari; Figueroa, Daniel G.; Rigopoulos, Gerasimos
2012-01-01
We consider a set of scalar fields, consisting of a single flat direction and one or several non-flat directions. We take our cue from the MSSM, considering separately D-flat and F-flat directions, but our results apply to any supersymmetric scenario containing flat directions. We study the field fluctuations during pure de Sitter inflation, following the evolution of the infrared modes by numerically solving the appropriate Langevin equations. We demonstrate that for the Standard Model U(1)Y, SU(2)L or SU(3)c gauge couplings, as well as for large enough Yukawa couplings, the fluctuations along the non-flat directions effectively block the fluctuations along the flat directions. The usual expected behaviour langlephi2rangleproptoN, with N the number of e-folds, may be strongly violated, depending on the coupling strengths. As a consequence, those cosmological considerations, which are derived assuming that during inflation flat directions fluctuate freely, should be revised.
Large Non-Gaussianity in Axion Inflation
Barnaby, Neil; Peloso, Marco
2011-05-06
The inflationary paradigm has enjoyed phenomenological success; however, a compelling particle physics realization is still lacking. Axions are among the best-motivated inflaton candidates, since the flatness of their potential is naturally protected by a shift symmetry. We reconsider the cosmological perturbations in axion inflation, consistently accounting for the coupling to gauge fields c{phi}FF-tilde, which is generically present in these models. This coupling leads to production of gauge quanta, which provide a new source of inflaton fluctuations, {delta}{phi}. For c > or approx. 10{sup 2}M{sub p}{sup -1}, these dominate over the vacuum fluctuations, and non-Gaussianity exceeds the current observational bound. This regime is typical for concrete realizations that admit a UV completion; hence, large non-Gaussianity is easily obtained in minimal and natural realizations of inflation.
Brane assisted quintessential inflation with transient acceleration
Bento, M. C.; Santos, N. M. C.; Gonzalez Felipe, R.
2008-06-15
A simple model of quintessential inflation with the modified exponential potential e{sup -{alpha}}{sup {phi}}[A+({phi}-{phi}{sub 0}){sup 2}] is analyzed in the braneworld context. Considering reheating via instant preheating, it is shown that the evolution of the scalar field {phi} from inflation to the present epoch is consistent with the observational constraints in a wide region of the parameter space. The model exhibits transient acceleration at late times for 0.96 < or approx. A{alpha}{sup 2} < or approx. 1.26 and 271 < or approx. {phi}{sub 0}{alpha} < or approx. 273, while permanent acceleration is obtained for 2.3x10{sup -8} < or approx. A{alpha}{sup 2} < or approx. 0.98 and 255 < or approx. {phi}{sub 0}{alpha} < or approx. 273. The steep parameter {alpha} is constrained to be in the range 5.3 < or approx. {alpha} < or approx. 10.8.
Brane inflation and the overshoot problem
NASA Astrophysics Data System (ADS)
Bird, Simeon; Peiris, Hiranya V.; Baumann, Daniel
2009-07-01
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 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. We present an analytic proof that the brane-inflationary attractor must be close to the slow-roll limit, and update the predictions for observables such as non-Gaussianity, cosmic string tension, and tensor modes.
On degenerate models of cosmic inflation
Gwyn, Rhiannon; Palma, Gonzalo A.; Sakellariadou, Mairi; Sypsas, Spyros E-mail: gpalmaquilod@ing.uchile.cl E-mail: s.sypsas@apctp.org
2014-10-01
In this article we discuss the role of current and future CMB measurements in pinning down the model of inflation responsible for the generation of primordial curvature perturbations. By considering a parameterization of the effective field theory of inflation with a modified dispersion relation arising from heavy fields, we derive the dependence of cosmological observables on the scale of heavy physics Λ{sub UV}. Specifically, we show how the f{sub NL} non-linearity parameters are related to the phase velocity of curvature perturbations at horizon exit, which is parameterized by Λ{sub UV}. BICEP2 and PLANCK findings are shown to be consistent with a value Λ{sub UV} ∼ Λ{sub GUT}. However, we find a degeneracy in the parameter space of inflationary models that can only be resolved with a detailed knowledge of the shape of the non-Gaussian bispectrum.
R sup 2 inflation in anisotropic universes
Berkin, A.L. Waseda University, Department of Physics, Okubo 3-4-1, Shinjuku-ku, Tokyo 169 )
1990-08-15
The evolution of Bianchi type-I and type-IX universes for a theory of gravity with an {epsilon}{ital R}{sup 2} term added to the usual Lagrangian is considered. As in the spatially flat Robertson-Walker case considered previously by others, inflation is found to occur. For any amount of initial anisotropy, the anisotropy decays quickly relative to the length of the inflationary epoch, and the amount of expansion is enhanced by the anisotropy. The exceptions are Bianchi type-IX universes near or at isotropy. In these cases a wide range of initial parameters causes the universe to recollapse, thus reducing the phase space in which inflation can occur. The diagonal metric is shown to be the most general form in the {ital R}{sup 2} theory for both Bianchi type-I universes with a perfect fluid and vacuum Bianchi type-IX models.
The Hubble flow of plateau inflation
Coone, Dries; Roest, Diederik; Vennin, Vincent E-mail: d.roest@rug.nl
2015-11-01
In the absence of CMB precision measurements, a Taylor expansion has often been invoked to parametrize the Hubble flow function during inflation. The standard ''horizon flow'' procedure implicitly relies on this assumption. However, the recent Planck results indicate a strong preference for plateau inflation, which suggests the use of Padé approximants instead. We propose a novel method that provides analytic solutions of the flow equations for a given parametrization of the Hubble function. This method is illustrated in the Taylor and Padé cases, for low order expansions. We then present the results of a full numerical treatment scanning larger order expansions, and compare these parametrizations in terms of convergence, prior dependence, predictivity and compatibility with the data. Finally, we highlight the implications for potential reconstruction methods.
Viscous warm inflation: Hamilton-Jacobi formalism
NASA Astrophysics Data System (ADS)
Akhtari, L.; Mohammadi, A.; Sayar, K.; Saaidi, Kh.
2017-04-01
Using Hamilton-Jacobi formalism, the scenario of warm inflation with viscous pressure is considered. The formalism gives a way of computing the slow-rolling parameter without extra approximation, and it is well-known as a powerful method in cold inflation. The model is studied in detail for three different cases of the dissipation and bulk viscous pressure coefficients. In the first case where both coefficients are taken as constant, it is shown that the case could not portray warm inflationary scenario compatible with observational data even it is possible to restrict the model parameters. For other cases, the results shows that the model could properly predicts the perturbation parameters in which they stay in perfect agreement with Planck data. As a further argument, r -ns and αs -ns are drown that show the acquired result could stand in acceptable area expressing a compatibility with observational data.
Plateau inflation in SUGRA-MSSM
NASA Astrophysics Data System (ADS)
Chakravarty, Girish Kumar; Gupta, Gaveshna; Lambiase, Gaetano; Mohanty, Subhendra
2016-09-01
We explored a Higgs inflationary scenario in the SUGRA embedding of the MSSM in Einstein frame where the inflaton is contained in the SU (2) Higgs doublet. We include all higher order non-renormalizable terms to the MSSM superpotential and an appropriate Kähler potential which can provide slow-roll inflaton potential in the D-flat direction. In this model, a plateau-like inflation potential can be obtained if the imaginary part of the neutral Higgs acts as the inflaton. The inflationary predictions of this model are consistent with the latest CMB observations. The model represents a successful Higgs inflation scenario in the context of Supergravity and it is compatible with Minimal Supersymmetric extension of the Standard Model.
Intermediate inflation driven by DBI scalar field
NASA Astrophysics Data System (ADS)
Nazavari, N.; Mohammadi, A.; Ossoulian, Z.; Saaidi, Kh.
2016-06-01
Picking out a DBI scalar field as inflation, the slow-rolling inflationary scenario is studied by attributing an exponential time function to scale factor, known as intermediate inflation. The perturbation parameters of the model are estimated numerically for two different cases, and the final result is compared with Planck data. The diagram of tensor-to-scalar ratio r versus scalar spectra index ns is illustrated, and it is found that they are within an acceptable range as suggested by Planck. In addition, the acquired values for amplitude of scalar perturbation reveal the ability of the model to depict a good picture of the Universe in one of its earliest stages. As a further argument, the non-Gaussianity is investigated, displaying that the model prediction stands in a 68% C.L. regime according to the latest Planck data.
Large field inflation from D-branes
NASA Astrophysics Data System (ADS)
Escobar, Dagoberto; Landete, Aitor; Marchesano, Fernando; Regalado, Diego
2016-04-01
We propose new large field inflation scenarios built on the framework of F-term axion monodromy. Our setup is based on string compactifications where D-branes create potentials for closed string axions via F-terms. Because the source of the axion potential is different from the standard sources of moduli stabilization, it is possible to lower the inflaton mass as compared to other massive scalars. We discuss a particular class of models based on type IIA flux compactifications with D6-branes. In the small field regime they describe supergravity models of quadratic chaotic inflation with a stabilizer field. In the large field regime the inflaton potential displays a flattening effect due to Planck suppressed corrections, allowing us to easily fit the cosmological parameters of the model within current experimental bounds.
Primordial non-Gaussianity from G inflation
Kobayashi, Tsutomu; Yamaguchi, Masahide; Yokoyama, Jun'ichi
2011-05-15
We present a comprehensive study of primordial fluctuations generated from G inflation, in which the inflaton Lagrangian is of the form K({phi},X)-G({phi},X){open_square}{phi} with X=-({partial_derivative}{phi}){sup 2}/2. The Lagrangian still gives rise to second-order gravitational and scalar field equations, and thus offers a more generic class of single-field inflation than ever studied, with a richer phenomenology. We compute the power spectrum and the bispectrum, and clarify how the non-Gaussian amplitude depends upon parameters such as the sound speed. In so doing we try to keep as great generality as possible, allowing for non slow-roll and deviation from the exact scale invariance.
Inflation from nilpotent Kähler corrections
NASA Astrophysics Data System (ADS)
McDonough, Evan; Scalisi, Marco
2016-11-01
We develop a new class of supergravity cosmological models where inflation is induced by terms in the Kähler potential which mix a nilpotent superfield S with a chiral sector Φ. As the new terms are non-(anti)holomorphic, and hence cannot be removed by a Kähler transformation, these models are intrinsically Kähler potential driven. Such terms could arise for example due to a backreaction of an anti-D3 brane on the string theory bulk geometry. We show that this mechanism is very general and allows for a unified description of inflation and dark energy, with controllable SUSY breaking at the vacuum. When the internal geometry of the bulk field is hyperbolic, we prove that small perturbative Kähler corrections naturally lead to α-attractor behaviour, with inflationary predictions in excellent agreement with the latest Planck data.
Inflation and pseudo-Goldstone Higgs boson
NASA Astrophysics Data System (ADS)
Alanne, Tommi; Sannino, Francesco; Tenkanen, Tommi; Tuominen, Kimmo
2017-02-01
We consider inflation within a model framework where the Higgs boson arises as a pseudo-Goldstone boson associated with the breaking of a global symmetry at a scale significantly larger than the electroweak one. We show that in such a model the scalar self-couplings can be parametrically suppressed and, consequently, the nonminimal couplings to gravity can be of order one or less, while the inflationary predictions of the model remain compatible with the precision cosmological observations. Furthermore, in the model we study, the existence of the electroweak scale is entirely due to the inflaton field. Our model therefore suggests that inflation and low energy particle phenomenology may be more entwined than assumed so far.
Small field inflation and the spectral index
Bose, Milton; Dine, Michael; Monteux, Angelo; Haskins, Laurel Stephenson
2014-01-27
It is sometimes stated that n{sub s}=0.98 in hybrid inflation; sometimes that it predicts n{sub s}>1. A number of authors have consider aspects of Planck scale corrections and argued that they affect these predictions. Here we consider these systematically, describing the situations which can yield n{sub s}=0.96, and the extent to which this result requires additional tuning.
Self-Healing, Inflatable, Rigidizable Shelter
NASA Technical Reports Server (NTRS)
Haight, Andrea; Gosau, Jan-Michael; Dixit, Anshu; Gleeson, Dan
2012-01-01
An inflatable, rigidizable shelter system was developed based on Rigi dization on Command (ROC) technology incorporating not only the requ ired low-stowage volume and lightweight character achieved from an i nflatable/rigidizable system, but also a self-healing foam system inc orporated between the rigidizable layers of the final structure to m inimize the damage caused by any punctures to the structure.
Baryon asymmetry, inflation and squeezed states
Bambah, Bindu A. . E-mail: bbsp@uohyd.ernet.in; Chaitanya, K.V.S. Shiv; Mukku, C.
2007-04-15
We use the general formalism of squeezed rotated states to calculate baryon asymmetry in the wake of inflation through parametric amplification. We base our analysis on a B and CP violating Lagrangian in an isotropically expanding universe. The B and CP violating terms originate from the coupling of complex fields with non-zero baryon number to a complex background inflaton field. We show that a differential amplification of particle and antiparticle modes gives rise to baryon asymmetry.
Modular Habitats Comprising Rigid and Inflatable Modules
NASA Technical Reports Server (NTRS)
Kennedy, Kriss J.
2010-01-01
Modular, lightweight, fully equipped buildings comprising hybrids of rigid and inflatable structures can be assembled on Earth and then transported to and deployed on the Moon for use as habitats. Modified versions of these buildings could also prove useful on Earth as shelters that can be rapidly and easily erected in emergency situations and/or extreme environments: examples include shelters for hurricane relief and for Antarctic exploration.
Susy seesaw inflation and NMSO(10)GUT
Aulakh, Charanjit S.
2013-05-23
We show that Supersymmetric models with Type I seesaw neutrino masses support slow roll inflection point inflation. The inflaton is the D-flat direction labelled by the chiral invariant HLN composed of the Higgs(H), slepton(L) and conjugate sneutrino(N) superfields. The scale of inflation and fine tuning is set by the conjugate neutrino Majorana mass M{sub {nu}{sup c}}{approx} 10{sup 6} - 10{sup 12} GeV. The cubic term in the (quartic) inflaton potential is dominantly from superpotential (not soft Susy breaking) couplings. The tuning conditions are thus insensitive to soft supersymmetry breaking parameters and are generically much less stringent than for previous 'A-term' inflation scenarios controlled by mass scales {approx}TeV. WMAP limits on the ratio of tensor to scalar perturbations limit the scale M controlling inflection point inflation: M < 7.9 Multiplication-Sign 10{sup 13} GeV. 'Instant preheating' is operative and dumps the inflaton energy into MSSM modes giving a high reheat temperature: T{sub rh} Almost-Equal-To M{sub {nu}{sup c(3/4)}}10{sup 6} GeV {approx} 10{sup 11} - 10{sup 15} GeV. A large gravitino mass > 50 TeV is therefore required to avoid over closure by reheat produced gravitinos. 'Instant preheating' and NLH inflaton facilitate production of right handed neutrinos during inflaton decay and thus non-thermal leptogenesis in addition to thermal leptogenesis. We show that the embedding in the fully realistic New Minimal Supersymmetric SO(10) GUT requires use of the heaviest righthanded neutrino mass as the controlling scale but the possibility of a measurable tensor scalar perturbation ratio seems marginal. We examine the parametric difficulties remaining.
Onset of inflation in loop quantum cosmology
Germani, Cristiano; Nelson, William; Sakellariadou, Mairi
2007-08-15
Using a Liouville measure, similar to the one proposed recently by Gibbons and Turok, we investigate the probability that single-field inflation with a polynomial potential can last long enough to solve the shortcomings of the standard hot big bang model, within the semiclassical regime of loop quantum cosmology. We conclude that, for such a class of inflationary models and for natural values of the loop quantum cosmology parameters, a successful inflationary scenario is highly improbable.
Hilltop supernatural inflation and gravitino problem
Kohri, Kazunori; Lin, Chia-Min E-mail: cmlin@phys.nthu.edu.tw
2010-11-01
In this paper, we explore the parameter space of hilltop supernatural inflation model and show the regime within which there is no gravitino problem even if we consider both thermal and nonthermal production mechanisms. We make plots for the allowed reheating temperature as a function of gravitino mass by constraints from big-bang nucleosynthesis. We also plot the constraint when gravitino is assumed to be stable and plays the role of dark matter.
Inflatable Emergency Atmospheric-Entry Vehicles
NASA Technical Reports Server (NTRS)
Jones, Jack; Hall, Jeffrey; Wu, Jiunn Jeng
2004-01-01
In response to the loss of seven astronauts in the Space Shuttle Columbia disaster, large, lightweight, inflatable atmospheric- entry vehicles have been proposed as means of emergency descent and landing for persons who must abandon a spacecraft that is about to reenter the atmosphere and has been determined to be unable to land safely. Such a vehicle would act as an atmospheric decelerator at supersonic speed in the upper atmosphere, and a smaller, central astronaut pod could then separate at lower altitudes and parachute separately to Earth. Astronaut-rescue systems that have been considered previously have been massive, and the cost of designing them has exceeded the cost of fabrication of a space shuttle. In contrast, an inflatable emergency-landing vehicle according to the proposal would have a mass between 100 and 200 kg, could be stored in a volume of approximately 0.2 to 0.4 cu m, and could likely be designed and built much less expensively. When fully inflated, the escape vehicle behaves as a large balloon parachute, or ballute. Due to very low mass-per-surface area, a large radius, and a large coefficient of drag, ballutes decelerate at much higher altitudes and with much lower heating rates than the space shuttle. Although the space shuttle atmospheric reentry results in surface temperatures of about 1,600 C, ballutes can be designed for maximum temperatures below 600 C. This allows ballutes to be fabricated with lightweight ZYLON(Registered TradeMark) or polybenzoxazole (PBO), or equivalent.
Violent preheating in inflation with nonminimal coupling
NASA Astrophysics Data System (ADS)
Ema, Yohei; Jinno, Ryusuke; Mukaida, Kyohei; Nakayama, Kazunori
2017-02-01
We study particle production at the preheating era in inflation models with nonminimal coupling ξphi2R and quartic potential λphi4/4 for several cases: real scalar inflaton, complex scalar inflaton and Abelian Higgs inflaton. We point out that the preheating proceeds much more violently than previously thought. If the inflaton is a complex scalar, the phase degree of freedom is violently produced at the first stage of preheating. If the inflaton is a Higgs field, the longitudinal gauge boson production is similarly violent. This is caused by a spike-like feature in the time dependence of the inflaton field, which may be understood as a consequence of the short time scale during which the effective potential or kinetic term changes suddenly. The produced particles typically have very high momenta k lesssim √λMP. The production might be so strong that almost all the energy of the inflaton is carried away within one oscillation for ξ2λ gtrsim Script O(100). This may partly change the conventional understandings of the (p)reheating after inflation with the nonminimal coupling to gravity such as Higgs inflation. We also discuss the possibility of unitarity violation at the preheating stage.
Hypersonic Inflatable Aerodynamic Decelerator Ground Test Development
NASA Technical Reports Server (NTRS)
Del Corso, Jospeh A.; Hughes, Stephen; Cheatwood, Neil; Johnson, Keith; Calomino, Anthony
2015-01-01
Hypersonic Inflatable Aerodynamic Decelerator (HIAD) technology readiness levels have been incrementally matured by NASA over the last thirteen years, with most recent support from NASA's Space Technology Mission Directorate (STMD) Game Changing Development Program (GCDP). Recently STMD GCDP has authorized funding and support through fiscal year 2015 (FY15) for continued HIAD ground developments which support a Mars Entry, Descent, and Landing (EDL) study. The Mars study will assess the viability of various EDL architectures to enable a Mars human architecture pathfinder mission planned for mid-2020. At its conclusion in November 2014, NASA's first HIAD ground development effort had demonstrated success with fabricating a 50 W/cm2 modular thermal protection system, a 400 C capable inflatable structure, a 10-meter scale aeroshell manufacturing capability, together with calibrated thermal and structural models. Despite the unquestionable success of the first HIAD ground development effort, it was recognized that additional investment was needed in order to realize the full potential of the HIAD technology capability to enable future flight opportunities. The second HIAD ground development effort will focus on extending performance capability in key technology areas that include thermal protection system, lifting-body structures, inflation systems, flight control, stage transitions, and 15-meter aeroshell scalability. This paper presents an overview of the accomplishments under the baseline HIAD development effort and current plans for a follow-on development effort focused on extending those critical technologies needed to enable a Mars Pathfinder mission.
The goldstone and goldstino of supersymmetric inflation
Kahn, Yonatan; Roberts, Daniel A.; Thaler, Jesse
2015-10-01
Here, we construct the minimal effective field theory (EFT) of supersymmetric inflation, whose field content is a real scalar, the goldstone for time-translation breaking, and a Weyl fermion, the goldstino for supersymmetry (SUSY) breaking. The inflating background can be viewed as a single SUSY-breaking sector, and the degrees of freedom can be efficiently parameterized using constrained superfields. Our EFT is comprised of a chiral superfield XNL containing the goldstino and satisfying X2NL = 0, and a real superfield BNL containing both the goldstino and the goldstone, satisfying XNL BNL = B3NL = 0. We match results from our EFT formalismmore » to existing results for SUSY broken by a fluid background, showing that the goldstino propagates with subluminal velocities. The same effect can also be derived from the unitary gauge gravitino action after embedding our EFT in supergravity. If the gravitino mass is comparable to the Hubble scale during inflation, we identify a new parameter in the EFT related to a time-dependent phase of the gravitino mass parameter. We briefly comment on the leading contributions of goldstino loops to inflationary observables.« less
The goldstone and goldstino of supersymmetric inflation
Kahn, Yonatan; Roberts, Daniel A.; Thaler, Jesse
2015-10-01
Here, we construct the minimal effective field theory (EFT) of supersymmetric inflation, whose field content is a real scalar, the goldstone for time-translation breaking, and a Weyl fermion, the goldstino for supersymmetry (SUSY) breaking. The inflating background can be viewed as a single SUSY-breaking sector, and the degrees of freedom can be efficiently parameterized using constrained superfields. Our EFT is comprised of a chiral superfield X_{NL} containing the goldstino and satisfying X^{2}_{NL} = 0, and a real superfield B_{NL} containing both the goldstino and the goldstone, satisfying X_{NL} B_{NL} = B^{3}_{NL} = 0. We match results from our EFT formalism to existing results for SUSY broken by a fluid background, showing that the goldstino propagates with subluminal velocities. The same effect can also be derived from the unitary gauge gravitino action after embedding our EFT in supergravity. If the gravitino mass is comparable to the Hubble scale during inflation, we identify a new parameter in the EFT related to a time-dependent phase of the gravitino mass parameter. We briefly comment on the leading contributions of goldstino loops to inflationary observables.
Axion models with high scale inflation
NASA Astrophysics Data System (ADS)
Moroi, Takeo; Mukaida, Kyohei; Nakayama, Kazunori; Takimoto, Masahiro
2014-11-01
We revisit the cosmological aspects of axion models. In the high-scale inflation scenario, the Peccei-Quinn (PQ) symmetry is likely to be restored during/after inflation. If the curvature of the PQ scalar potential at the origin is smaller than its vacuum expectation value; for instance in a class of SUSY axion models, thermal inflation happens before the radial component of the PQ scalar (saxion) relaxes into the global minimum of the potential and the decay of saxion coherent oscillation would produce too much axion dark radiation. In this paper, we study how to avoid the overproduction of axion dark radiation with some concrete examples. We show that, by taking account of the finite-temperature dissipation effect appropriately, the overproduction constraint can be relaxed since the PQ scalar can take part in the thermal plasma again even after the PQ phase transition. We also show that it can be further relaxed owing to the late time decay of another heavy CP-odd scalar, if it is present.
Beginning inflation in an inhomogeneous universe
East, William E.; Kleban, Matthew; Linde, Andrei; ...
2016-09-06
Using numerical solutions of the full Einstein field equations coupled to a scalar inflaton field in 3+1 dimensions, we study the conditions under which a universe that is initially expanding, highly inhomogeneous and dominated by gradient energy can transition to an inflationary period. If the initial scalar field variations are contained within a sufficiently flat region of the inflaton potential, and the universe is spatially flat or open on average, inflation will occur following the dilution of the gradient and kinetic energy due to expansion. This is the case even when the scale of the inhomogeneities is comparable to themore » initial Hubble length, and overdense regions collapse and form black holes, because underdense regions continue expanding, allowing inflation to eventually begin. In conclusion, this establishes that inflation can arise from highly inhomogeneous initial conditions and solve the horizon and flatness problems, at least as long as the variations in the scalar field do not include values that exceed the inflationary plateau.« less
Ultralight inflatable fresnel lens solar concentrators
NASA Astrophysics Data System (ADS)
O'Neill, Mark J.; Piszczor, Michael F.
1998-01-01
Since 1986, ENTECH and NASA Lewis have been developing refractive solar concentrators for space applications. These Fresnel lens concentrators can be configured as either point-focus dome lenses or line-focus cylindrical lenses. Small point-focus or line-focus lenses can be used to concentrate sunlight onto solar cells in space photovoltaic (PV) arrays. Large point-focus lenses can be used for high solar flux applications. In March 1997, a NASA Phase I SBIR program was initiated to develop ultralight inflatable lenses of both the line-focus and point-focus types. Special program emphasis is being placed on large point-focus lenses for various high-concentration applications, including solar dynamic (SD) power, alkali metal thermal energy conversion (AMTEC), thermophotovoltaics (TPV), and solar thermal propulsion (STP). Key outputs of the Phase I program include conceptual designs, optical performance predictions, micrometeoroid puncture analyses, manufacturing process identification, and functional prototype hardware. This paper summarizes the key results of the Phase I program, leading to the conclusion that inflatable dome lenses will provide excellent high-concentration optical performance, unequaled shape error tolerance, extremely low mass/aperture area ratio, proven manufacturability with space qualified materials, and small make-up gas requirements to maintain inflation on-orbit.
Reheating in Gauss-Bonnet-coupled inflation
NASA Astrophysics Data System (ADS)
van de Bruck, Carsten; Longden, Chris; Dimopoulos, Konstantinos
2016-07-01
We investigate the feasibility of models of inflation with a large Gauss-Bonnet coupling at late times, which have been shown to modify and prevent the end of inflation. Despite the potential of Gauss-Bonnet models in predicting favorable power spectra, capable of greatly lowering the tensor-to-scalar ratio compared to now-disfavored models of standard chaotic inflation, it is important to also understand in what context it is possible for postinflationary (p)reheating to proceed and hence recover an acceptable late-time cosmology. We argue that in the previously studied inverse power law coupling case, reheating cannot happen due to a lack of oscillatory solutions for the inflaton, and that neither instant preheating nor gravitational particle production would avoid this problem due to the persistence of the inflaton's energy density, even if it were to partially decay. Hence we proceed to define a minimal generalization of the model which can permit perturbative reheating and study the consequences of this, including heavily modified dynamics during reheating and predictions of the power spectra.
Inflatable rigidizable human habitat of large size
NASA Astrophysics Data System (ADS)
Kondyurin, Alexey
Human organism is sensitive to space environment factors such as temperature variations, ra-diation, microgravity, that exist in all space missions on the board of space ships and space stations on Low Earth Orbit (LEO). The materials and constructions of modern space ships and ISS provide acceptable conditions for human crew during some months on the LEO. Fu-ture space flights to Moon, Mars and further will require new materials and stronger protection against high intensity solar irradiation, which could kill living organisms when flight is over the radiation belt of Earth. One of the modern project for future space flight is a large size habitat based on inflatable technology with rigidization of the habitat walls after deployment. The requirements for radiation protection, stable inflating, rigidization and sufficient mechan-ical properties during long life-time of the habitat are key question for selection of a suitable materials of the habitat. The properties of the inflatable rigidizable habitat to save life in far space are considered and discussed.
Inflatable Re-Entry Vehicle Experiment (IRVE) Design Overview
NASA Technical Reports Server (NTRS)
Hughes, Stephen J.; Dillman, Robert A.; Starr, Brett R.; Stephan, Ryan A.; Lindell, Michael C.; Player, Charles J.; Cheatwood, F. McNeil
2005-01-01
Inflatable aeroshells offer several advantages over traditional rigid aeroshells for atmospheric entry. Inflatables offer increased payload volume fraction of the launch vehicle shroud and the possibility to deliver more payload mass to the surface for equivalent trajectory constraints. An inflatable s diameter is not constrained by the launch vehicle shroud. The resultant larger drag area can provide deceleration equivalent to a rigid system at higher atmospheric altitudes, thus offering access to higher landing sites. When stowed for launch and cruise, inflatable aeroshells allow access to the payload after the vehicle is integrated for launch and offer direct access to vehicle structure for structural attachment with the launch vehicle. They also offer an opportunity to eliminate system duplication between the cruise stage and entry vehicle. There are however several potential technical challenges for inflatable aeroshells. First and foremost is the fact that they are flexible structures. That flexibility could lead to unpredictable drag performance or an aerostructural dynamic instability. In addition, durability of large inflatable structures may limit their application. They are susceptible to puncture, a potentially catastrophic insult, from many possible sources. Finally, aerothermal heating during planetary entry poses a significant challenge to a thin membrane. NASA Langley Research Center and NASA's Wallops Flight Facility are jointly developing inflatable aeroshell technology for use on future NASA missions. The technology will be demonstrated in the Inflatable Re-entry Vehicle Experiment (IRVE). This paper will detail the development of the initial IRVE inflatable system to be launched on a Terrier/Orion sounding rocket in the fourth quarter of CY2005. The experiment will demonstrate achievable packaging efficiency of the inflatable aeroshell for launch, inflation, leak performance of the inflatable system throughout the flight regime, structural