692 research outputs found
Stoponium Search at Photon Linear Collider
In some supersymmetric extensions of the Standard Model fairly light
superpartner of t-quark is predicted, which may form bound states ({\it
stoponiums}) under certain conditions. We study prospects of search for
stoponium at the future Photon Linear Collider. It is found that this machine
could be the best machine for discovery and study of these resonances at some
scenarios of supersymmetric extension of the Standard Model. In particular, if
the decay channel is dominant stoponium could be observed at the beginning
of PLC run with collision energy tuned at the stoponium mass. If this channel
is kinematically closed stoponium could be discovered in ,
and decay channels but higher statistics are needed. Effects of the
stoponium-Higgs mixing and degeneracy are briefly discussed.Comment: 11 pages, 2 figures added, corrections taken into account result in
increasing of signal significanc
Non-Universality of the Specific Heat in Glass Forming Systems
We present new simulation results for the specific heat in a classical model
of a binary mixture glass-former in two dimensions. We show that in addition to
the formerly observed specific heat peak there is a second peak at lower
temperatures which was not observable in earlier simulations. This is a
surprise, as most texts on the glass transition expect a single specific heat
peak. We explain the physics of the two specific heat peaks by the
micro-melting of two types of clusters. While this physics is easily
accessible, the consequences are that one should not expect any universality in
the temperature dependence of the specific heat in glass formers
Accretion and outflow activity on the late phases of pre-main-sequence evolution. The case of RZ Piscium
RZ Psc is an isolated high-latitude post-T Tauri star that demonstrates a UX
Ori-type photometric activity. The star shows very weak spectroscopic
signatures of accretion, but at the same time possesses the unusual footprints
of the wind in Na I D lines. In the present work we investigate new
spectroscopic observations of RZ Psc obtained in 2014 during two observation
runs. We found variable blueshifted absorption components (BACs) in lines of
the other alcali metals, K I 7699 \AA\ and Ca II IR triplet. We also confirmed
the presence of a weak emission component in the H line, which allowed
us to estimate the mass accretion rate on the star as Msun yr. We could not reveal any clear periodicity in the
appearance of BACs in sodium lines. Nevertheless, the exact coincidence of the
structure and velocities of the Na I D absorptions observed with the interval
of about one year suggests that such a periodicity should exist
Mechanical Properties of Glass Forming Systems
We address the interesting temperature range of a glass forming system where
the mechanical properties are intermediate between those of a liquid and a
solid. We employ an efficient Monte-Carlo method to calculate the elastic
moduli, and show that in this range of temperatures the moduli are finite for
short times and vanish for long times, where `short' and `long' depend on the
temperature. By invoking some exact results from statistical mechanics we offer
an alternative method to compute shear moduli using Molecular Dynamics
simulations, and compare those to the Monte-Carlo method. The final conclusion
is that these systems are not "viscous fluids" in the usual sense, as their
actual time-dependence concatenates solid-like materials with varying local
shear moduli
Structure And Properties of Nanoparticles Formed under Conditions of Wire Electrical Explosion
Structure and properties of nanoparticles formed under conditions of wire
electrical explosion were studied. It was shown that the state of WEE power
particles can be characterized as a metastable state. It leads to an increased
stability of nanopowders at normal temperatures and an increased reactivity
during heating, which is revealed in the form of threshold phenomena.Comment: Submitted on behalf of TIMA Editions
(http://irevues.inist.fr/tima-editions
Higgs Boson Discovery Potential of LHC in the Channel
We discuss the SM Higgs discovery potential of LHC in the reaction when the jet is observed at sufficiently high to
be reliably identified. We conclude that this channel gives promising discovery
possibilities for the Higgs boson mass range 100-140 GeV, during LHC operation
at a low luminosity. With 30 fb of accumulated data and for
GeV about 100 signal events could be observed with the number of background
events larger by a factor of 2 only, showing a signal significance
. We use the difference of distributions in the partonic
subprocess energy for the signal and background for a better
separation of the signal.Comment: 15 pages including 6 figures, LaTeX, use epsfig.sty. To appear in
Phys.Lett.B. In this replacement minor LaTeX improvements are mad
High resolution spectroscopic study of red clump stars in the Galaxy: iron group elements
The main atmospheric parameters and abundances of the iron group elements
(vanadium, chromium, iron, cobalt and nickel) are determined for 62 red giant
"clump" stars revealed in the Galactic field by the Hipparcos orbiting
observatory. The stars form a homogeneous sample with the mean value of
temperature T=4750 +- 160K, of surface gravity log g = 2.41 +- 0.26 and the
mean value of metallicity [Fe/H] = -0.04 +- 0.15 dex. A Gaussian fit to the
[Fe/H] distribution produces the mean [Fe/H] = -0.01 dex and dispersion of
[Fe/H] = 0.08 dex. The near-solar metallicity and small dispersion of [Fe/H] of
clump stars of the Galaxy obtained in this work confirm the theoretical model
of the Hipparcos clump by Girardi & Salaris (2001). This suggests that nearby
clump stars are (in the mean) relatively young objects, reflecting mainly the
near-solar metallicities developed in the local disk during the last few Gyrs
of its history. We find iron group element to iron abundance ratios in clump
giants to be close to solar.Comment: 9 pages, 7 figures, accepted for publication in MNRA
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