2,508 research outputs found
Extracting Scattering Phase-Shifts in Higher Partial-Waves from Lattice QCD Calculations
L\"uscher's method is routinely used to determine meson-meson, meson-baryon
and baryon-baryon s-wave scattering amplitudes below inelastic thresholds from
Lattice QCD calculations - presently at unphysical light-quark masses. In this
work we review the formalism and develop the requisite expressions to extract
phase-shifts describing meson-meson scattering in partial-waves with
angular-momentum l<=6 and l=9. The implications of the underlying cubic
symmetry, and strategies for extracting the phase-shifts from Lattice QCD
calculations, are presented, along with a discussion of the signal-to-noise
problem that afflicts the higher partial-waves.Comment: 79 pages, 41 figure
Thermally-induced magnetic phases in an Ising spin Kondo lattice model on a kagome lattice at 1/3-filling
Numerical investigation on the thermodynamic properties of an Ising spin
Kondo lattice model on a kagome lattice is reported. By using Monte Carlo
simulation, we investigated the magnetic phases at 1/3-filling. We identified
two successive transitions from high-temperature paramagnetic state to a
Kosterlitz-Thouless-like phase in an intermediate temperature range and to a
partially disordered phase at a lower temperature. The partially disordered
state is characterized by coexistence of antiferromagnetic hexagons and
paramagnetic sites with period . We compare the results
with those for the triangular lattice case.Comment: 4 pages, 2 figure
Kaon B parameter from quenched Lattice QCD
We present results of a large-scale simulation for the Kaon B parameter
in quenched lattice QCD with the Kogut-Susskind quark action. Calculating
at 1% statistical accuracy for seven values of lattice spacing in the range
fm on lattices up to , we verify a
quadratic dependence of theoretically predicted. Strong indications
are found that, with our level of accuracy, terms
arising from our one-loop matching procedure have to be included in the
continuum extrapolation. We present (NDR, 2 GeV)=0.628(42) as our final
value, as obtained by a fit including the term.Comment: 8 pages, Latex(revtex, epsf), 2 epsf figure
Reactivity of Monoterpene Criegee Intermediates at Gas-Liquid Interfaces
Biogenic monoterpenes are major sources of Criegee intermediates (CIs) in the troposphere. Recent studies underscored the importance of their heterogeneous chemistry. The study of monoterpene CI reactions on liquid surfaces, however, is challenging due to the lack of suitable probes. Here, we report the first mass spectrometric detection of the intermediates and products, which include labile hydroperoxides, from reactions of CIs of representative monoterpenes (α-terpinene, γ-terpinene, terpinolene, D-limonene, α-pinene) with water, cis-pinonic acid (CPA) and octanoic acid (OA) on the surface of liquid microjets. Significantly, the relative yields of α-hydroxy-hydroperoxides production from CIs hydration at the gas–liquid interface—α-terpinene (1.00) ≫ D-limonene (0.18) > γ-terpinene (0.11) ∼ terpinolene (0.10) ≫ α-pinene (0.01)—do not track the rate constants of their gas-phase ozonolyses. Notably, in contrast with the inertness of the other CIs, the CIs derived from α-terpinene ozonolysis readily react with CPA and OA to produce C_(20) and C_(18) ester hydroperoxides, respectively. Present results reveal hitherto unknown structural effects on the reactivities of CIs at aqueous interfaces
Water Dramatically Accelerates the Decomposition of α-Hydroxyalkyl-Hydroperoxides in Aerosol Particles
α-Hydroxyalkyl-hydroperoxides (α-HHs), from the addition of water to Criegee intermediates in the ozonolysis of olefins, are reactive components of organic aerosols. Assessing the fate of α-HHs in such media requires information on the rates and products of their reactions in aqueous organic matrices. This information, however, is unavailable due to the lack of analytical techniques for the detection and identification of labile α-HHs. Here, we report the mass spectrometric detection (as Cl- adducts) of the α-HH produced in the ozonolysis of a C_(15) diolefin in water (W):acetonitrile (AN) mixtures of variable composition. α-HH decays into a gem-diol + H_2O_2 in τ_(1/e) ~ 52 min in 50% (v:v) water, but persists longer than a day in < 10% water mixtures. The strong non-linear dependence of τ_(1/e) on water content reveals that water content is a major factor controlling the fate of α-HHs in atmospheric particles, and suggests that α-HH decomposes while embedded in W_nAN_m clusters rather than randomly dissolved in molecularly homogeneous W:AN mixtures
Water Dramatically Accelerates the Decomposition of α-Hydroxyalkyl-Hydroperoxides in Aerosol Particles
α-Hydroxyalkyl-hydroperoxides (α-HHs), from the addition of water to Criegee intermediates in the ozonolysis of olefins, are reactive components of organic aerosols. Assessing the fate of α-HHs in such media requires information on the rates and products of their reactions in aqueous organic matrices. This information, however, is unavailable due to the lack of analytical techniques for the detection and identification of labile α-HHs. Here, we report the mass spectrometric detection (as Cl- adducts) of the α-HH produced in the ozonolysis of a C_(15) diolefin in water (W):acetonitrile (AN) mixtures of variable composition. α-HH decays into a gem-diol + H_2O_2 in τ_(1/e) ~ 52 min in 50% (v:v) water, but persists longer than a day in < 10% water mixtures. The strong non-linear dependence of τ_(1/e) on water content reveals that water content is a major factor controlling the fate of α-HHs in atmospheric particles, and suggests that α-HH decomposes while embedded in W_nAN_m clusters rather than randomly dissolved in molecularly homogeneous W:AN mixtures
The Strange Prospects for Astrophysics
The implications of the formation of strange quark matter in neutron stars
and in core-collapse supernovae is discussed with special emphasis on the
possibility of having a strong first order QCD phase transition at high baryon
densities. If strange quark matter is formed in core-collapse supernovae
shortly after the bounce, it causes the launch of a second outgoing shock which
is energetic enough to lead to a explosion. A signal for the formation of
strange quark matter can be read off from the neutrino spectrum, as a second
peak in antineutrinos is released when the second shock runs over the
neutrinosphere.Comment: 10 pages, 8 figures, invited talk given at the international
conference on strangeness in quark matter (SQM2008), Beijing, October 6-10,
Beijing, China, version to appear in J. Phys.
One Spin Trace Formalism for
It has been known for some time that there are two methods to calculate with staggered fermions: one is the two spin trace formalism and the other is
the one spin trace formalism. Until now, the two spin trace formalism has been
exclusively used for weak matrix element calculations with staggered fermions.
Here, the one spin trace formalism to calculate with staggered fermions
is explained. It is shown that the one spin trace operators require additional
chiral partner operators in order to keep the continuum chiral behavior. The
renormalization of the one spin trace operators is described and compared with
the two spin trace formalism.Comment: 47 pages, latex, 4 figures are available on reques
Heavy-Light Decay Constants: Conclusions from the Wilson Action
We report on the results of a MILC collaboration calculation of ,
, , and their ratios. We discuss the most important
errors in more detail than we have elsewhere.Comment: LATTICE98(heavyqk) 3 latex pages and 3 postscript figures. The
perturbative correction calculated by Kuramashi has been adjusted to take
into account the fact that we match to the continuum at the kinetic mass of
the heavy meson, not the pole mass. This produces a 2 to 4 MeV change in
final results for decay constants, and has negligible effect on decay
constant ratio
Tables of Hyperonic Matter Equation of State for Core-Collapse Supernovae
We present sets of equation of state (EOS) of nuclear matter including
hyperons using an SU_f(3) extended relativistic mean field (RMF) model with a
wide coverage of density, temperature, and charge fraction for numerical
simulations of core collapse supernovae. Coupling constants of Sigma and Xi
hyperons with the sigma meson are determined to fit the hyperon potential
depths in nuclear matter, U_Sigma(rho_0) ~ +30 MeV and U_Xi(rho_0) ~ -15 MeV,
which are suggested from recent analyses of hyperon production reactions. At
low densities, the EOS of uniform matter is connected with the EOS by Shen et
al., in which formation of finite nuclei is included in the Thomas-Fermi
approximation. In the present EOS, the maximum mass of neutron stars decreases
from 2.17 M_sun (Ne mu) to 1.63 M_sun (NYe mu) when hyperons are included. In a
spherical, adiabatic collapse of a 15 star by the hydrodynamics
without neutrino transfer, hyperon effects are found to be small, since the
temperature and density do not reach the region of hyperon mixture, where the
hyperon fraction is above 1 % (T > 40 MeV or rho_B > 0.4 fm^{-3}).Comment: 23 pages, 6 figures (Fig.3 and related comments on pion potential are
corrected in v3.
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