4,684 research outputs found
Energy and momentum deposited into a QCD medium by a jet shower
Hard partons moving through a dense QCD medium lose energy by radiative
emissions and elastic scatterings. Deposition of the radiative contribution
into the medium requires rescattering of the radiated gluons. We compute the
total energy loss and its deposition into the medium self-consistently within
the same formalism, assuming perturbative interaction between probe and medium.
The same transport coefficients that control energy loss of the hard parton
determine how the energy is deposited into the medium; this allows a parameter
free calculation of the latter once the former have been computed or extracted
from experimental energy loss data. We compute them for a perturbative medium
in hard thermal loop (HTL) approximation. Assuming that the deposited
energy-momentum is equilibrated after a short relaxation time, we compute the
medium's hydrodynamical response and obtain a conical pattern that is strongly
enhanced by showering.Comment: 4 pages, 3 figures, revtex4, intro modified, typos correcte
A comparative study of Jet-quenching Schemes
The four major approximation schemes devised to study the modification of
jets in dense matter are outlined. The comparisons are restricted to basic
assumptions and approximations made in each case and the calculation
methodology used. Emergent underlying similarities between apparently disparate
methods brought about by the approximation schemes are exposed.
Parameterizations of the medium in each scheme are discussed in terms of the
transport coefficient . Discrepancies between the estimates obtained
from the four schemes are discussed. Recent developments in the basic theory
and phenomenology of energy loss are highlighted.Comment: 12 pages, 10 figures, latex, plenary presentation at the 19th
International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions
(QM2006), Shanghai, China Nov. 14-20, 200
Air Pollution in South Texas: A Short Communication of Health Risks and Implications
Air pollution is a major public health concern. The region of South Texas in the United States has experienced high levels of air pollution in recent years due to an increase in population, cross-border trade between the U.S.A. and Mexico, and high vehicular activity. This review assesses the relationships between human health and air pollution in South Texas. A thorough scientific search was performed using PubMed, Science Direct, and ProQuest, with most of the literature focusing on the source apportionment of particulate matter that is 2.5 microns or less in width (PM2.5), Carbon Dioxide (CO2), carbon monoxide (CO), Black Carbon (BC), and associated health risks for children and pregnant women. Findings from the source apportionment studies suggest the role of industries, automobiles emissions, agricultural burning, construction work, and unpaved roads in the overall deterioration of air quality and deleterious health effects, such as respiratory and cardiovascular diseases. This review demonstrates the pressing need for more air pollution and health effects studies in this region, especially the Brownsville–Harlingen–McAllen metropolitan area
Alpha-Nucleon Scattering by Extended Hulthén Potential
307-312The phase shift analysis of any nucleon- nucleon scattering is an important aspect for both local and non-local potentials
to know different properties of any nuclear system. The Phase Function Method (PFM) effectively determines the scattering
phase shifts for both local and non local potentials. We use PFM for the local extended Hulthén potential and solve the first
order phase equation to generate scattering phase shifts for different states of (α-n) and (α-p) systems. We demonstrate the
merit of our approach by computing the phase shift data with and without some correction factors and comparing it with
standard experimental results
Parton energy loss due to synchrotron-like gluon emission
We develop a quasiclassical theory of the synchrotron-like gluon radiation.
Our calculations show that the parton energy loss due to the synchrotron gluon
emission may be important in the jet quenching phenomenon if the plasma
instabilities generate a sufficiently strong chromomagnetic field. Our gluon
spectrum disagrees with that obtained by Shuryak and Zahed within the
Schwinger's proper time method.Comment: 11 pages, 3 eps figure
Transport Theoretical Description of Collisional Energy Loss in Infinite Quark-Gluon Matter
We study the time evolution of a high-momentum gluon or quark propagating
through an infinite, thermalized, partonic medium utilizing a Boltzmann
equation approach. We calculate the collisional energy loss of the parton,
study its temperature and flavor dependence as well as the the momentum
broadening incurred through multiple interactions. Our transport calculations
agree well with analytic calculations of collisional energy-loss where
available, but offer the unique opportunity to address the medium response as
well in a consistent fashion.Comment: 12 pages, updated with additional references and typos correcte
Multiparticle angular correlations: a probe for the sQGP at RHIC
A novel decomposition technique is used to extract the centrality dependence
of di-jet properties and yields from azimuthal correlation functions obtained
in Au+Au collisions at =200 GeV. The width of the
near-side jet shows very little dependence on centrality. In contrast, the
away-side jet indicates substantial broadening as well as hints for for a local
minimum at for central and mid-central events. The yield of
jet-pairs (per trigger particle) slowly increases with centrality for both the
near- and away-side jets. These observed features are compatible with several
recent theoretical predictions of possible modifications of di-jet
fragmentation by a strongly interacting medium. Several new experimental
approaches, including the study of flavor permutation and higher order
multi-particle correlations, that might help to distinguish between different
theoretical scenarios are discussed.Comment: Proceedings of the MIT workshop on correlations and fluctation
Ruling Out Multi-Order Interference in Quantum Mechanics
Quantum mechanics and gravitation are two pillars of modern physics. Despite
their success in describing the physical world around us, they seem to be
incompatible theories. There are suggestions that one of these theories must be
generalized to achieve unification. For example, Born's rule, one of the axioms
of quantum mechanics could be violated. Born's rule predicts that quantum
interference, as shown by a double slit diffraction experiment, occurs from
pairs of paths. A generalized version of quantum mechanics might allow
multi-path, i.e. higher order interferences thus leading to a deviation from
the theory. We performed a three slit experiment with photons and bounded the
magnitude of three path interference to less than 10-2 of the expected two-path
interference, thus ruling out third and higher order interference and providing
a bound on the accuracy of Born's rule. Our experiment is consistent with the
postulate both in semi-classical and quantum regimes
One-pot synthesis of multifunctional ZnO nanomaterials: study of superhydrophobicity and UV photosensing property
ZnO nanomaterials are synthesized using one-pot synthesis method. Equimolar solution of Zinc Nitrate hexahydrate (Zn(NO3)(2).6H(2)O) and Hexamethylenetetramine (C6H12N4) is used as a precursor for ZnO formation. Different nanostructures of ZnO are achieved by controlling the pH of the growth solution in the range 2-12 (acidic to alkali). ZnO nanostructures are evaluated for hydrophobic property using static contact angle measurement setup and UV photosensing activity. Surface morphology, structural properties and compositional analysis of ZnO nanostructures are examined by field emission scanning electron microscope (FE-SEM), energy dispersive X-ray analysis (EDX), high-resolution transmission electron microscope (FEG-TEM) and X-ray diffraction (XRD) measurements. Existence of ZnO wurtzite structure is confirmed from XRD study and is analyzed by Rietveld refinement method. Nanomaterials are characterized using Raman spectroscopy which confirms highest oxygen deficiency in ZnO nanorods. The material shows remarkable superhydrophobic and UV photosensing property and hence the name multifunctional. Among all morphologies grown at different pH values, ZnO nanorods show superhydrophobic nature with contact angle more than 170 degrees. Total surface energy value of ZnO nanostructures is calculated using Wendt two-component theory. Different ZnO nanostructures (with variation of pH value) are used to study UV photosensing property. Responsivity and photocurrent show a strong dependence on the morphology of ZnO
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