837 research outputs found
2-inch diameter (100) β-Ga2O3 crystal growth by the vertical Bridgman technique in a resistance heating furnace in ambient air
Available online 20 May 2020ArticleJOURNAL OF CRYSTAL GROWTH.545:125724(2020)journal articl
Spectroscopy of Heavy Mesons Expanded in 1/m_Q
Operating just once with the naive Foldy-Wouthuysen-Tani transformation on
the relativistic Fermi-Yang equation for bound states described by
the semi-relativistic Hamiltonian which includes Coulomb-like as well as
confining scalar potentials, we have calculated heavy meson mass spectra of D
and B together with higher spin states. Based on the formulation recently
proposed, their masses and wave functions are expanded up to the second order
in with a heavy quark mass and the lowest order equation is
examined carefully to obtain a complete set of eigenfunctions for the
Schr\"odinger equation. Heavy quark effective theory parameters, ,
, and , are also determined at the first and second order
in .Comment: 49 pages, 5 epsf figure
Heavy Flavor Hadrons in Statistical Hadronization of Strangeness-rich QGP
We study b, c quark hadronization from QGP. We obtain the yields of charm and
bottom flavored hadrons within the statistical hadronization model. The
important novel feature of this study is that we take into account the high
strangeness and entropy content of QGP, conserving strangeness and entropy
yields at hadronization.Comment: v2 expended: 20 pages, 23 figures, 5 tables, in press EPJ-
Molecular structure of the Bs0*(5725) and Bs1(5778) bottom-strange mesons
We discuss a possible interpretation of the scalar Bs0*(5725) and axial
Bs1(5778) bottom-strange mesons as hadronic molecules - bound states of B K and
B* K mesons, respectively. Using a phenomenological Lagrangian approach we
analyze the strong Bs0* to Bs pi0, Bs1 to Bs* pi0 and the radiative Bs0* to Bs*
gamma, Bs1 to Bs gamma, Bs1 to Bs* gamma, Bs1 to Bs0* gamma decays. We give
predictions for the decay properties: effective couplings and decay widths.Comment: 21 pages, 7 figure
General structure of the graviton self-energy
The graviton self-energy at finite temperature depends on fourteen structure
functions. We show that, in the absence of tadpoles, the gauge invariance of
the effective action imposes three non-linear relations among these functions.
The consequences of such constraints, which must be satisfied by the thermal
graviton self-energy to all orders, are explicitly verified in general linear
gauges to one loop order.Comment: 4 pages, minor corrections of typo
Thermal one- and two-graviton Green's functions in the temporal gauge
The thermal one- and two-graviton Green's function are computed using a
temporal gauge. In order to handle the extra poles which are present in the
propagator, we employ an ambiguity-free technique in the imaginary-time
formalism. For temperatures T high compared with the external momentum, we
obtain the leading T^4 as well as the subleading T^2 and log(T) contributions
to the graviton self-energy. The gauge fixing independence of the leading T^4
terms as well as the Ward identity relating the self-energy with the one-point
function are explicitly verified. We also verify the 't Hooft identities for
the subleading T^2 terms and show that the logarithmic part has the same
structure as the residue of the ultraviolet pole of the zero temperature
graviton self-energy. We explicitly compute the extra terms generated by the
prescription poles and verify that they do not change the behavior of the
leading and sub-leading contributions from the hard thermal loop region. We
discuss the modification of the solutions of the dispersion relations in the
graviton plasma induced by the subleading T^2 contributions.Comment: 17 pages, 5 figures. Revised version to be published in Phys. Rev.
Schubert calculus of Richardson varieties stable under spherical Levi subgroups
We observe that the expansion in the basis of Schubert cycles for
of the class of a Richardson variety stable under a spherical Levi subgroup is
described by a theorem of Brion. Using this observation, along with a
combinatorial model of the poset of certain symmetric subgroup orbit closures,
we give positive combinatorial descriptions of certain Schubert structure
constants on the full flag variety in type . Namely, we describe
when and are inverse to Grassmannian permutations with unique descents
at and , respectively. We offer some conjectures for similar rules in
types and , associated to Richardson varieties stable under spherical
Levi subgroups of SO(2n+1,\C) and SO(2n,\C), respectively.Comment: Section 4 significantly shortened, and other minor changes made as
suggested by referees. Final version, to appear in Journal of Algebraic
Combinatoric
Energy security cost as an externality—increased gas import price and economy of Ukraine
In this research, the tolerability of the economy of Ukraine for the increase of the gas import price is investigated. The relationship between the economic growth and imported gas price is analyzed, and it was found that the gas consumption of the food and other smaller industries was growing while the gas price was increasing; although, the larger industries such as chemical and manufacturing industries reduced the gas consumption. It was also found that Ukraine may hold a capability to lower the gas import price to the degree comparable to the current price. For the analysis, the national statistics of every month from 2002 through 2008 was used with the least squares model and the ARMA model for time-series forecasting. The data contains the GDP, the imported gas price and volume, the PPIs for the food industry, the chemical industry, the manufacturers and the energy industry, as well as the gas volumes consumed by the industries of low price band, other than the manufacturers and the chemical industries.Досліджено стійкість економіки України при зростаючій ціні на імпортований газ. Запропоновано методологію моделювання і прогнозування фінансово-економічних процесів, яка ґрунтується на ієрархічній процедурі пошуку структури і оптимізації параметрів моделей. Виконано аналіз залежності економічного зростання та ціни на імпортований газ. Цей аналіз виявив, що споживання газу для виробництва продуктів харчування та в інших, більш дрібних галузях виробництва, зростає при загальному зростанні ціни на імпортований газ. Тоді як крупніші галузі, такі як хімічна та виробнича, зменшували споживання газу під час зростання його ціни. Також виявлено можливість знижувати ціну на імпортований газ для України до рівня порівняного з поточною ціною.Исследована устойчивость экономики Украины при растущей цене на импортированный газ. Предложена методология моделирования и прогнозирования финансово-экономических процессов, которая базируется на иерархической процедуре поиска структуры и оптимизации параметров моделей. Выполнен анализ зависимости экономического роста и цены на импортированный газ. Этот анализ выявил, что потребление газа при производстве продуктов питания и в других, более мелких отраслях производства растет при общем росте цен на импортированный газ. Тогда как более крупные отрасли, такие как химическая и производственная, снижали потребление газа при росте его цены. Также выявлена возможность снижать цену на импортированный газ для Украины до уровня, сопоставимого с текущей ценой
String compactification, QCD axion and axion-photon-photon coupling
It is pointed out that there exist a few problems to be overcome toward an
observable sub-eV QCD axion in superstring compactification. We give a general
expression for the axion decay constant. For a large domain wall number
, the axion decay constant can be substantially lowered from a generic
value of a scalar singlet VEV. The Yukawa coupling structure in the recent
model is studied completely, including the needed nonrenormalizable
terms toward realistic quark and lepton masses. In this model we find an
approximate global symmetry and vacuum so that a QCD axion results but its
decay constant is at the GUT scale. The axion-photon-photon coupling is
calculated for a realistic vacuum satisfying the quark and lepton mass matrix
conditions. It is the first time calculation of in
realistic string compactifications: .Comment: 33 pages, 2 figures, JHEP format, some errors in the superpotential
couplings are corrected and the following discussions are changed
correspondingl
Effects of S-wave thresholds
The opening of a new S-wave threshold is frequently accompanied by an abrupt
dip in the magnitude of an amplitude for an already-open channel. One familiar
example is the behavior of the I=0 S-wave scattering amplitude at threshold. Numerous other examples of this phenomenon in recent data
are noted, and a unified description of the underlying dynamics is sought.Comment: 17 pages, 2 figures. Two additional references; typographic
correction. To be published in Phys. Rev.
- …