192 research outputs found
Inflation and Reheating in Spontaneously Generated Gravity
Inflation is studied in the context of induced gravity (IG) , where is the Ricci scalar, a scalar field and a
dimensionless constant, and diverse symmetry-breaking potentials
are considered. In particular we compared the predictions for Landau-Ginzburg
(LG) and Coleman-Weinberg (CW) type potentials and their possible
generalizations with the most recent data. We find that large field inflation
generally leads to fewer constraints on the parameters and the shape of the
potential whereas small field inflation is more problematic and, if viable,
implies more constraints, in particular on the parameter . We also
examined the reheating phase and obtained an accurate analytical solution for
the dynamics of inflaton and the Hubble parameter by using a multiple scale
analysis (MSA). The solutions were then used to study the average expansion of
the Universe, the average equation of state for the scalar field and both the
perturbative and resonant decays of the inflaton field.Comment: 15 pages, 10 figures, to be published in Phys. Rev.
Phylogeographyc inferences from the mtDNA variation of the three-toed skink, Chalcides chalcides (Reptilia: Scincidae)
Genetic diversity was analyzed in Chalcides chalcides populations from peninsular Italy, Sardinia, Sicily and Tunisia by sequencing 400 bp at the 50 end of the mitochondrial gene encoding cytochrome b (cyt b) and by restriction fragment length polymorphism (RFLP) analysis of two mitochondrial DNA segments (ND-1/2 and ND-3/4). The results of the phylogenetic analysis highlighted the presence of three main clades corresponding with three of the four main geographical areas (Tunisia, Sicily and the Italian peninsula), while Sardinia proved to be closely related to Tunisian haplotypes suggesting a colonization of this island from North Africa by human agency in historical times. On the contrary, the splitting times estimated on the basis of cyt b sequence data seem to indicate a more ancient colonization of Sicily and the Italian Peninsula, as a consequence of tectonic and climatic events that affected the Mediterranean Basin during the Pleistocene. Finally, the analysis of the genetic variability of C. chalcides populations showed a remarkable genetic homogeneity in Italian populations when compared to the Tunisian ones. This condition could be explained by a rapid post-glacial expansion from refugial populations that implied serial bottlenecking with progressive loss of haplotypes, resulting in a low genetic diversity in the populations inhabiting the more recently colonized areas
Status of the Cylindical-GEM project for the KLOE-2 Inner Tracker
The status of the R&D on the Cylindrical-GEM (CGEM) detector foreseen as
Inner Tracker for KLOE-2, the upgrade of the KLOE experiment at the DAFNE
phi-factory, will be presented. The R&D includes several activities: i) the
construction and complete characterization of the full-size CGEM prototype,
equipped with 650 microns pitch 1-D longitudinal strips; ii) the study of the
2-D readout with XV patterned strips and operation in magnetic field (up to
1.5T), performed with small planar prototypes in a dedicated test at the H4-SPS
beam facility; iii) the characterization of the single-mask GEM technology for
the realization of large-area GEM foils.Comment: 4 pages, 10 figures, Presented at Vienna Conference on
Instrumentation (Feb 15-20, 2010, Vienna, Austria). Submitted to the
Proceeding
Inflation and Reheating in Induced Gravity
Inflation is studied in the context of induced gravity (IG) , where is the Ricci scalar, a scalar field and a
dimensionless constant. We study in detail cosmological perturbations in IG and
examine both a Landau-Ginzburg (LG) and a Coleman-Weinberg (CW) potential toy
models for small field and large field (chaotic) inflation and find that small
field inflationary models in IG are constrained to by WMAP 5 yrs data. Finally we describe the regime of coherent
oscillations in induced gravity by an analytic approximation, showing how the
homogeneous inflaton can decay in its short-scale fluctuations when it
oscillates around a non-zero value .Comment: 5 pages, 2 figure
Performance of the cylindrical-GEM prototype for the inner tracker of KLOE-2
We developed a low mass, fully cylindrical and dead-zone-free GEM detector as inner tracker for the KLOE experiment upgrade at the DAFNE Φ-factory. The proposed detector, that opens the way for a new and competitive category of ultra-light, full sensitive vertex detectors for high energy physics experiments, will play a crucial role in the study of the K S and η rare decays and in the measurement of the neutral kaon interferometry. The main physics requirements are: good spatial resolutions, σ(rφ) = 200 µm and σ(z) = 500 µm and a very low material budget, 2% of X 0 for the whole detector. The inner tracker will be composed by five layers of cylindrical triple-GEM detectors (CGEM), covering the space from the beam pipe to the inner wall of the KLOE Drift Chamber (from 150 mm to 250 mm radius). Each CGEM is realized inserting one into the other the required five cylindrical structures made of thin (50 µ m) polyimide foils: the cathode, the three GEMs and the anode readout. In order to avoid the use of support frames inside the sensitive volume, the cylindrical GEMs are mechanically stretched from their ends where annular fiberglass frames are glued. The final result is a very light detector: only 0.2% of X 0 per layer inside the active area. A full scale prototype (300 mm diameter, 360 mm length) of the first layer of the inner tracker has been successfully built and characterized under different experimental conditions. After a brief description of the construction procedure, the results of the extensive tests are presented
Efecto De La Fertilizacion Fosforo Azufrada Sobre El Sistema Radical Y El Rendimiento De Soja En El Centro De Argentina
The objective was to evaluate grain the effect of sulfur and phosphorus fertilization on root growth, nodules and soybean yield. The test was performed at 25 km west of Coronel Baigorria department Río Cuarto; Córdoba, Argentina on a Haplustol entic from the series Alpa Corral. Treatments applied were made different doses of single superphosphate (21% P205 y 12% de S).TO: control treatment, no fertilizerT1: 5,5 Kg ha-1de P y 7,2 Kg ha-1de S; T2: 10,9 Kg ha-1de P y 14,4 Kg ha-1 de S y T3: 16,48 Kg ha-1 de P y 21 Kg ha-1.During crop cycle the following observations and measurements: emerged seedlings, root dry weight, number of nodules, primary root diameter, root length density (DLR), and determine harvest, crop yield (kg/ha) and levels of available soil phosphorus at harvest. In this research project the application of phosphorus-sulfur fertilizer produced changes in soybean root system, by increasing dry weight of roots, generating lateral growth, improving the symbiosis with nitrogen-fixing bacteria which result in more number of nodules per root. Fertilization also modified rooting patterns increasing DLR in most fertilizer treatments, effects that resulted in an increase in soybeans yield
A Cylindrical GEM Inner Tracker for the BESIII experiment at IHEP
The Beijing Electron Spectrometer III (BESIII) is a multipurpose detector
that collects data provided by the collision in the Beijing Electron Positron
Collider II (BEPCII), hosted at the Institute of High Energy Physics of
Beijing. Since the beginning of its operation, BESIII has collected the world
largest sample of J/{\psi} and {\psi}(2s). Due to the increase of the
luminosity up to its nominal value of 10^33 cm-2 s-1 and aging effect, the MDC
decreases its efficiency in the first layers up to 35% with respect to the
value in 2014. Since BESIII has to take data up to 2022 with the chance to
continue up to 2027, the Italian collaboration proposed to replace the inner
part of the MDC with three independent layers of Cylindrical triple-GEM (CGEM).
The CGEM-IT project will deploy several new features and innovation with
respect the other current GEM based detector: the {\mu}TPC and analog readout,
with time and charge measurements will allow to reach the 130 {\mu}m spatial
resolution in 1 T magnetic field requested by the BESIII collaboration. In this
proceeding, an update of the status of the project will be presented, with a
particular focus on the results with planar and cylindrical prototypes with
test beams data. These results are beyond the state of the art for GEM
technology in magnetic field
Development of CGEM technology for ultra-light tracking detectors : the KLOE-2 Inner Tracker
KLOE-2 at the -factory DA\Phi NE of INFN Laboratori Nazionali di Frascati (LNF), is the first experiment using the GEM technology with a cylindrical geometry (CGEM), developed at the LNF by the Inner Tracker group and within the RD51 Collaboration. Four layers with 26 41 cm diameters and L = 70 cm, each realized as a Triple-GEM detector, compose this new detector. To produce GEM foils of unprecedented size, the novel single-mask manufacturing procedure has been developed with the TE-MPE-EM CERN group, together with the realization of a novel XV readout pattern. The adopted solutions allowed the total material budget to be kept below 2% of the radiation length . The final assembly of the Inner Tracker has been completed on March 14, 2014. The production procedure will be reported together with the validation test results
Particle Probe of Horava-Lifshitz Gravity
Kehagias-Sfetsos black hole in Ho\v{r}ava-Lifshitz gravity is probed through
particle geodesics. Gravitational force of KS black hole becomes weaker than
that of Schwarzschild around horizon and interior space. Particles can be
always scattered or trapped in new closed orbits, unlike those falling forever
in Schwarzschild black. The properties of null and timelike geodesics are
classified with values of coupling constants. The precession rates of the
orbits are evaluated. The time trajectories are also classified under different
values of coupling constants for both null and timelike geodesics. Physical
phenomena that may be observable are discussed.Comment: 10 pages, 8 figure
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