25,461 research outputs found
Studying Diquark Structure of Heavy Baryons in Relativistic Heavy Ion Collisions
We propose the enhancement of yield in heavy ion collisions at
RHIC and LHC as a novel signal for the existence of diquarks in the strongly
coupled quark-gluon plasma produced in these collisions as well as in the
. Assuming that stable bound diquarks can exist in the quark-gluon
plasma, we argue that the yield of would be increased by two-body
collisions between diquarks and quarks, in addition to normal
three-body collisions among , and quarks. A quantitative study of
this effect based on the coalescence model shows that including the
contribution of diquarks to production indeed leads to a
substantial enhancement of the ratio in heavy ion collisions.Comment: Prepared for Chiral Symmetry in Hadron and Nuclear Physics
(Chiral07), Nov. 13-16, 2007, Osaka, Japa
Chaos at the border of criticality
The present paper points out to a novel scenario for formation of chaotic
attractors in a class of models of excitable cell membranes near an
Andronov-Hopf bifurcation (AHB). The mechanism underlying chaotic dynamics
admits a simple and visual description in terms of the families of
one-dimensional first-return maps, which are constructed using the combination
of asymptotic and numerical techniques. The bifurcation structure of the
continuous system (specifically, the proximity to a degenerate AHB) endows the
Poincare map with distinct qualitative features such as unimodality and the
presence of the boundary layer, where the map is strongly expanding. This
structure of the map in turn explains the bifurcation scenarios in the
continuous system including chaotic mixed-mode oscillations near the border
between the regions of sub- and supercritical AHB. The proposed mechanism
yields the statistical properties of the mixed-mode oscillations in this
regime. The statistics predicted by the analysis of the Poincare map and those
observed in the numerical experiments of the continuous system show a very good
agreement.Comment: Chaos: An Interdisciplinary Journal of Nonlinear Science
(tentatively, Sept 2008
The Second Virial Coefficient of Spin-1/2 Interacting Anyon System
Evaluating the propagator by the usual time-sliced manner, we use it to
compute the second virial coefficient of an anyon gas interacting through the
repulsive potential of the form . All the cusps for the
unpolarized spin-1/2 as well as spinless cases disappear in the
limit, where is a frequency of harmonic oscillator which is introduced
as a regularization method. As approaches to zero, the result reduces to
the noninteracting hard-core limit.Comment: 9 pages, 2 figs include
Current Challenges in the Development of Quantum Dot Sensitized Solar Cells
This is the peer reviewed version of the following article: Current Challenges in the Development of Quantum Dot Sensitized Solar Cells, which has been published in final form at https://doi.org/10.1002/aenm.202001774. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.Quantum dot sensitized solar cells (QDSSCs) have experienced a continuous performance growth in the past years presenting a photoconversion efficiency > 13%. QDSSCs constitute a smart approach to take advantage of the properties of semiconductor quantum dots (QDs), mitigating the transport constrains. In contrast with other QD solar cell configurations, for QDSSCs, the record efficiencies have been reported with Pb and Cdâfree based sensitizers. The development of techniques in order to provide photoanodes with very high QD loading and the discovery of new electrolytes, including all solid configurations, are the most important future challenges that this technology must address to further increase cell performance and stability
Ytterbium doped nano-crystalline optical fiber for reduced photodarkening
We report suppression of photodarkening in Yb-doped nano-crystalline fibers in silica host. The photodarkening induced loss reduced by 20 times compared to Yb-doped aluminosilicate fibers. The laser efficiency of the nano-crystalline fiber was 79%
Quantum mutual entropy for Jaynes-Cummings model
The dynamics of an atom on the Jaynes-Cummings model has been studied by an
atomic inversion, von Neumann entropy and so on. In this letter, we will treat
the Jaynes-Cummings model as a problem in non-equilibrium statistical mechanics
and apply quantum mutual entropy to study the irreversible dynamics of a state
for the atom on this model.Comment: RevTeX, 4 pages with a figure(eps file), submitted to Physical Review
Letter
The influence of position in overlap joints of Mg and Al alloys on microstructure and hardness of laser welds
Structure and properties of laser beam welding zone of dissimilar materials, AZ31 magnesium alloy and A5754 Aluminum alloy, are investigated. The microstructure and quality of the Mg/Al weld were studied by metallography, microhardness and optical microscopy. Differences in physical and mechanical properties of both materials, magnesium and aluminum, affect weldability and resistance of this combination, and lead to the formation of intermetallic compounds in the welded metal
New Perspective on Galaxy Clustering as a Cosmological Probe: General Relativistic Effects
We present a general relativistic description of galaxy clustering in a FLRW
universe. The observed redshift and position of galaxies are affected by the
matter fluctuations and the gravity waves between the source galaxies and the
observer, and the volume element constructed by using the observables differs
from the physical volume occupied by the observed galaxies. Therefore, the
observed galaxy fluctuation field contains additional contributions arising
from the distortion in observable quantities and these include tensor
contributions as well as numerous scalar contributions. We generalize the
linear bias approximation to relate the observed galaxy fluctuation field to
the underlying matter distribution in a gauge-invariant way. Our full formalism
is essential for the consistency of theoretical predictions. As our first
application, we compute the angular auto correlation of large-scale structure
and its cross correlation with CMB temperature anisotropies. We comment on the
possibility of detecting primordial gravity waves using galaxy clustering and
discuss further applications of our formalism.Comment: 10 pages, 2 figures, accepted for publication in Physical Review
Procedural Fairness in Antitrust Enforcement: The U.S. Perspective
Due process and fairness in enforcement procedures represent a critical aspect of the rule of law. Allowing greater participation by the parties and making enforcement procedures more transparent serve several functions, including better decisionmaking, greater respect for government, stronger economic growth, promotion of investment, limits corruption and politically motivated actions, regulation of bureaucratic ambition, and greater control of agency staff whose vision do not align with agency leadership or who are using an enforcement matter to advance their careers. That is why such distinguished actors as the International Competition Network (ICN), the Organization for Economic Cooperation and Development (OECD), the Association of Southeast Asian Nations (ASEAN), the International Chamber of Commerce (ICC), and the American Bar Association (ABA) have all offered frameworks for promoting greater fairness in antitrust enforcement.
Because the U.S. was the first country to enact an antitrust law, it has enjoyed the longest opportunity to develop its enforcement practices. As such, after first introducing the key antitrust enforcement institutions, this chapter will explore the manner in which U.S. implements four key procedural protections (legal representation, notice of the legal basis and evidence underlying the alleged violation, engagement between the parties and the investigative staff, and internal checks and balances/judicial review) to provide insights into ways to improve U.S. law and in the hopes that other jurisdictions might benefit from the U.S. experience
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