2,553 research outputs found
Composite Inflation from Super Yang-Mills, Orientifold and One-Flavor QCD
Recent investigations have shown that inflation can be driven by
four-dimensional strongly interacting theories non-minimally coupled to
gravity. We explore this paradigm further by considering composite inflation
driven by orientifold field theories. The advantage of using these theories
resides in the fact that at large number of colors they feature certain super
Yang-Mills properties. In particular we can use for inflation the bosonic part
of the Veneziano-Yankielowicz effective theory. Furthermore, we include the 1/N
as well as fermion mass corrections at the effective Lagrangian level allowing
us to explore the effects of these corrections on the inflationary slow-roll
parameters. Additionally the orientifold field theory with fermionic matter
transforming according to the two-index antisymmetric representation for three
colors is QCD. Therefore this model can be interpreted as a new non-minimally
coupled QCD theory of inflation. The scale of composite inflation, for all the
models presented here, is of the order of GeV. Unitarity studies of
the inflaton scattering suggest that the cutoff of the model is at the Planck
scale.Comment: 17 page
Marginally Deformed Starobinsky Gravity
We show that quantum-induced marginal deformations of the Starobinsky
gravitational action of the form , with the Ricci scalar
and a positive parameter, smaller than one half, can account for the
recent experimental observations by BICEP2 of primordial tensor modes. We also
suggest natural microscopic (non) gravitational sources of these corrections
and demonstrate that they lead generally to a nonzero and positive .
Furthermore we argue, that within this framework, the tensor modes probe
theories of grand unification with a large scalar field content.Comment: 5 pages, 1 figure, 2 column
Stellar activity as noise in exoplanet detection I. Methods and application to solar-like stars and activity cycles
The detection of exoplanets using any method is prone to confusion due to the
intrinsic variability of the host star. We investigate the effect of cool
starspots on the detectability of the exoplanets around solar-like stars using
the radial velocity method. For investigating this activity-caused "jitter" we
calculate synthetic spectra using radiative transfer, known stellar atomic and
molecular lines, different surface spot configurations, and an added planetary
signal. Here, the methods are described in detail, tested and compared to
previously published studies. The methods are also applied to investigate the
activity jitter in old and young solar-like stars, and over a solar-like
activity cycles. We find that the mean full jitter amplitude obtained from the
spot surfaces mimicking the solar activity varies during the cycle
approximately between 1 m/s and 9 m/s. With a realistic observing frequency a
Neptune mass planet on a one year orbit can be reliably recovered. On the other
hand, the recovery of an Earth mass planet on a similar orbit is not feasible
with high significance. The methods developed in this study have a great
potential for doing statistical studies of planet detectability, and also for
investigating the effect of stellar activity on recovered planetary parameters.Comment: Accepted to MNRA
Deep far infrared ISOPHOT survey in "Selected Area 57", I. Observations and source counts
We present here the results of a deep survey in a 0.4 sq.deg. blank field in
Selected Area 57 conducted with the ISOPHOT instrument aboard ESAs Infrared
Space Observatory (ISO) at both 60 um and 90 um. The resulting sky maps have a
spatial resolution of 15 x 23 sq.arcsec. per pixel which is much higher than
the 90 x 90 sq.arcsec. pixels of the IRAS All Sky Survey. We describe the main
instrumental effects encountered in our data, outline our data reduction and
analysis scheme and present astrometry and photometry of the detected point
sources. With a formal signal to noise ratio of 6.75 we have source detection
limits of 90 mJy at 60 um and 50 mJy at 90 um. To these limits we find
cumulated number densities of 5+-3.5 per sq.deg. at 60 um and 14.8+-5.0 per
sq.deg.at 90 um. These number densities of sources are found to be lower than
previously reported results from ISO but the data do not allow us to
discriminate between no-evolution scenarios and various evolutionary models.Comment: 15 pages, 11 figures, accepted by Astronomy & Astrophysic
Waxing Monkey Frogs in the Wild
This is where the abstract of this record would appear. This is only demonstration data
Form and width of spectral line of Josephson Flux-Flow oscillator
The behavior of a Josephson flux-flow oscillator in the presence of both bias
current and magnetic field fluctuations has been studied. To derive the
equation for slow phase dynamics in the limit of small noise intensity the
Poincare method has been used. Both the form of spectral line and the linewidth
of the flux-flow oscillator have been derived exactly on the basis of technique
presented in the book of Malakhov, known limiting cases are considered, limits
of their applicability are discussed and appearance of excess noise is
explained. Good coincidence of theoretical description with experimental
results has been demonstrated.Comment: 10 pages, 5 figure
Time-series Spectroscopy of Pulsating sdB stars III: Line Indices of PG1605+072
We present the detection and analysis of line index variations in the
pulsating sdB star PG 1605+072. We have found a strong dependence of line index
amplitude on Balmer line order, with high-order Balmer line amplitudes up to 10
times larger than H-beta. Using a simple model, we have found that the line
index may not only be dependent on temperature, as is usually assumed for
oscillating stars, but also on surface gravity. This information will provide
another set of observables that can be used for mode identification of sdBs.Comment: 8 pages, 9 figures, to appear in MNRAS. A high resolution version of
Figure 3 can be found at
http://www.sternwarte.uni-erlangen.de/~ai25/MC852-fig3.ep
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