6,888 research outputs found
Threshold and Flavour Effects in the Renormalization Group Equations of the MSSM II: Dimensionful couplings
We re-examine the one-loop renormalization group equations (RGEs) for the
dimensionful parameters of the minimal supersymmetric Standard Model with
broken supersymmetry, allowing for arbitrary flavour structure of the soft SUSY
breaking (SSB) parameters. We include threshold effects by evaluating the
-functions in a sequence of (non-supersymmetric) effective theories with
heavy particles decoupled at the scale of their mass. We present the most
general form for high scale SSB parameters that obtains if we assume that the
supersymmetry breaking mechanism does not introduce new inter-generational
couplings. This form, possibly amended to allow additional sources of
flavour-violation, serves as a boundary condition for solving the RGEs for the
dimensionful MSSM parameters. We then present illustrative examples of
numerical solutions to the RGEs. We find that in a SUSY GUT with the scale of
SUSY scalars split from that of gauginos and higgsinos, the gaugino mass
unification condition may be violated by (10%). As another
illustration, we show that in mSUGRA, the rate for the flavour-violating
decay obtained using the complete RGE solution is
smaller than that obtained using the commonly-used "single-step" integration of
the RGEs by a factor 10-25, and so may qualitatively change expectations for
topologies from top-squark pair production at colliders. Together with the RGEs
for dimensionless couplings presented in a companion paper, the RGEs in
Appendix B of this paper form a complete set of one-loop MSSM RGEs that include
threshold and flavour-effects necessary for two-loop accuracy.Comment: 96 pages, 14 figures, revtex4, multirow.sty, bm.sty, amsmath.sty;
Corrected Fig. 3 and Eqs. (B9), (B11), (B13) - (B20) and (B24). Results
change by less than 1
High-resolution imaging of planet host candidates. A comprehensive comparison of different techniques
The Kepler mission has discovered thousands of planet candidates. Currently,
some of them have already been discarded; more than 200 have been confirmed by
follow-up observations, and several hundreds have been validated. However, most
of them are still awaiting for confirmation. Thus, priorities (in terms of the
probability of the candidate being a real planet) must be established for
subsequent observations. The motivation of this work is to provide a set of
isolated (good) host candidates to be further tested by other techniques. We
identify close companions of the candidates that could have contaminated the
light curve of the planet host. We used the AstraLux North instrument located
at the 2.2 m telescope in the Calar Alto Observatory to obtain
diffraction-limited images of 174 Kepler objects of interest. The lucky-imaging
technique used in this work is compared to other AO and speckle imaging
observations of Kepler planet host candidates. We define a new parameter, the
blended source confidence level (BSC), to assess the probability of an object
to have blended non-detected eclipsing binaries capable of producing the
detected transit. We find that 67.2% of the observed Kepler hosts are isolated
within our detectability limits, and 32.8% have at least one visual companion
at angular separations below 6 arcsec. We find close companions (below 3
arcsec) for the 17.2% of the sample. The planet properties of this sample of
non-isolated hosts are revised. We report one possible S-type binary
(KOI-3158). We also report three possible false positives (KOIs 1230.01,
3649.01, and 3886.01) due to the presence of close companions. The BSC
parameter is calculated for all the isolated targets and compared to both the
value prior to any high-resolution image and, when possible, to observations
from previous high-spatial resolution surveys in the Kepler sample.Comment: Accepted for publication in A&A on April 29, 2014; 32 pages, 11
figures, 11 table
Cloaking by coating: How effectively does a thin, stiff coating hide a soft substrate?
From human tissue to fruits, many soft materials are coated by a thin layer
of a stiffer material. While the primary role of such a coating is often to
protect the softer material, the thin, stiff coating also has an important
effect on the mechanical behaviour of the composite material, making it appear
significantly stiffer than the underlying material. We study this cloaking
effect of a coating for the particular case of indentation tests, which measure
the `firmness' of the composite solid: we use a combination of theory and
experiment to characterize the firmness quantitatively. We find that the
indenter size plays a key role in determining the effectiveness of cloaking:
small indenters feel a mixture of the material properties of the coating and of
the substrate, while large indenters sense largely the unadulterated substrate
Renormalisation Group Analysis of Supersymmetric Particle Interactions
In the Minimal Supersymmetric Standard Model (MSSM), there are numerous
sources of flavour-violation in addition to the usual Kobayashi-Maskawa mixing
matrix of the Standard Model. We reexamine the renormalisation group equations
(RGEs) with a view to investigating flavour effects in a supersymmetric theory
with an arbitrary flavour structure at some high scale. To incorporate
(two-loop sized) threshold effects in the one-loop RGEs, we calculate the
beta-functions using a sequence of (non-supersymmetric) effective theories with
heavy particles decoupled at the scale of their mass, keeping track of the fact
that many couplings (such as gauge and gaugino couplings) which are equal in an
exact supersymmetric theory may no longer be equal once the supersymmetry
(SUSY) is broken. We find that this splitting, which is ignored in the
literature, may be larger than two-loop terms that are included. In addition,
gaugino couplings develop flavour structure that is absent without including
decoupling effects. A program (to be incorporated into ISAJET) has been
developed, which includes flavour-violating couplings of superparticles and
solves the two-loop threshold RGEs subject to specified high scale inputs. The
weak scale flavour structure derived in this way can be applied to the study of
flavour-changing decays of SUSY particles. As an illustration, we revisit the
branching ratio of the flavour-violating decay of the top squark. We find that,
in the minimal supergravity (mSUGRA) class of models, previous estimates for
the width of this decay have been too large by a factor 10-25. We also analyse
the consequences of introducing non-universality in the high scale soft
SUSY-breaking mass matrices and find that under these conditions the partial
width can be altered by a large amount.Comment: PhD Dissertation, approx. 212 pages, 22 figures, 5 table
The Opossum (\u3ci\u3eDidelphis virginiana\u3c/i\u3e) as a Host for \u3ci\u3eSarcocystis debonei\u3c/i\u3e from Cowbirds (\u3ci\u3eMolothrus ater\u3c/i\u3e) and Grackles (\u3ci\u3eCassidix mexicanus\u3c/i\u3e, \u3ci\u3eQuiscalus quiscula\u3c/i\u3e)
Sarcocystis-infected muscles from ducks, cowbirds, and grackles were fed to cats, opossums, rats, and a dog. Only the opossum (Didelphis virginiana) was a suitable definitive host. All opossums that were fed Sarcocystis-infected cowbirds (Molothrus ater) and grackles (Cassidix mexicanus and Quiscalus quiscula) passed sporocysts in their feces. Opossums that ate the cowbirds had prepatent periods of 5 and 10 days and remained patent for at least 105 days. Opossums that ate the grackles became patent on day 10 after the infective meal and remained patent for over 90 (Quiscalus) and 105 (Cassidix) days. A single opossum fed infected muscle from a pintail duck (Anas acuta) passed sporocysts in the feces from days 13 through 18 after infection. No sporocysts were passed by opossums fed infected muscle from the green-winged teal (Anas carolinensis) and shoveller (Spatula clypeata). Sporocysts of duck, cowbird, and grackle origin were structurally similar. Mean dimensions of sporocysts were: duck-origin, 11.2 by 8.2 μm; cowbird-origin, 11.4 by 7.8 μm; Cassidix-origin, 11.2 by 7.8 μm; and Quiscalus-origin, 11.6 by 7.7 μm. We designate the sporocysts of cowbird and grackle origin as Sarcocystis debonei Vogelsang, 1929 (Syn. Isospora boughtoni Volk, 1938)
The Opossum (\u3ci\u3eDidelphis virginiana\u3c/i\u3e) as a Host for \u3ci\u3eSarcocystis debonei\u3c/i\u3e from Cowbirds (\u3ci\u3eMolothrus ater\u3c/i\u3e) and Grackles (\u3ci\u3eCassidix mexicanus\u3c/i\u3e, \u3ci\u3eQuiscalus quiscula\u3c/i\u3e)
Sarcocystis-infected muscles from ducks, cowbirds, and grackles were fed to cats, opossums, rats, and a dog. Only the opossum (Didelphis virginiana) was a suitable definitive host. All opossums that were fed Sarcocystis-infected cowbirds (Molothrus ater) and grackles (Cassidix mexicanus and Quiscalus quiscula) passed sporocysts in their feces. Opossums that ate the cowbirds had prepatent periods of 5 and 10 days and remained patent for at least 105 days. Opossums that ate the grackles became patent on day 10 after the infective meal and remained patent for over 90 (Quiscalus) and 105 (Cassidix) days. A single opossum fed infected muscle from a pintail duck (Anas acuta) passed sporocysts in the feces from days 13 through 18 after infection. No sporocysts were passed by opossums fed infected muscle from the green-winged teal (Anas carolinensis) and shoveller (Spatula clypeata). Sporocysts of duck, cowbird, and grackle origin were structurally similar. Mean dimensions of sporocysts were: duck-origin, 11.2 by 8.2 μm; cowbird-origin, 11.4 by 7.8 μm; Cassidix-origin, 11.2 by 7.8 μm; and Quiscalus-origin, 11.6 by 7.7 μm. We designate the sporocysts of cowbird and grackle origin as Sarcocystis debonei Vogelsang, 1929 (Syn. Isospora boughtoni Volk, 1938)
Kepler-539: a young extrasolar system with two giant planets on wide orbits and in gravitational interaction
We confirm the planetary nature of Kepler-539b (aka Kepler object of interest
K00372.01), a giant transiting exoplanet orbiting a solar-analogue G2 V star.
The mass of Kepler-539b was accurately derived thanks to a series of precise
radial velocity measurements obtained with the CAFE spectrograph mounted on the
CAHA 2.2m telescope. A simultaneous fit of the radial-velocity data and Kepler
photometry revealed that Kepler-539b is a dense Jupiter-like planet with a mass
of Mp = 0.97 Mjup and a radius of Rp = 0.747 Rjup, making a complete circular
revolution around its parent star in 125.6 days. The semi-major axis of the
orbit is roughly 0.5 au, implying that the planet is at roughly 0.45 au from
the habitable zone. By analysing the mid-transit times of the 12 transit events
of Kepler-539b recorded by the Kepler spacecraft, we found a clear modulated
transit time variation (TTV), which is attributable to the presence of a planet
c in a wider orbit. The few timings available do not allow us to precisely
estimate the properties of Kepler-539c and our analysis suggests that it has a
mass between 1.2 and 3.6 Mjup, revolving on a very eccentric orbit (0.4<e<0.6)
with a period larger than 1000 days. The high eccentricity of planet c is the
probable cause of the TTV modulation of planet b. The analysis of the CAFE
spectra revealed a relatively high photospheric lithium content, A(Li)=2.48
dex, which, together with both a gyrochronological and isochronal analysis,
suggests that the parent star is relatively young.Comment: 11 pages, 14 figures, accepted for publication in Astronomy &
Astrophysic
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