4,580 research outputs found
Energy dependence of -"" effective potential derived from coupled-channel Green's function
We investigate the energy dependence of a single-channel effective potential
between the and the ""-core nucleus, which can be obtained as an
-"" equivalent local potential from a coupled-channel model for
- systems. It turns out that the imaginary part of
the resultant potential near the decay threshold can well
approximate the phase space suppression factor of
decay modes. The effects on the pole position of the state in
the channel are also discussed.Comment: 4 pages, 2 figures, Proceedings of the International Conference on
Exotic Atoms and Related Topics (EXA2011), September 5-9, 2011, Wien,
Austria, to appear in Hyperfine Interaction
Transverse single-spin asymmetries in proton-proton collisions at the AFTER@LHC experiment
We present results for transverse single-spin asymmetries in proton-proton
collisions at kinematics relevant for AFTER, a proposed fixed-target experiment
at the Large Hadron Collider. These include predictions for pion, jet, and
direct photon production from analytical formulas already available in the
literature. We also discuss specific measurements that will benefit from the
higher luminosity of AFTER, which could help resolve an almost 40-year puzzle
of what causes transverse single-spin asymmetries in proton-proton collisions.Comment: 10 pages, 4 figures; more details/discussion added to the text,
references added/updated, version to appear in Advances in High Energy
Physics for the Special Issue "Physics at a Fixed-Target Experiment Using the
LHC Beams
N=2 Supermultiplet of Currents and Anomalous Transformations in Supersymmetric Gauge Theory
We examine some properties of supermultiplet consisting of the U(1)_{J}
current, extended supercurrents, energy-momentum tensor and the central charge
in N=2 supersymmetric Yang-Mills theory. The superconformal improvement
requires adding another supermultiplet beginning with the U(1)_{R} current. We
determine the anomalous (quantum mechanical) supersymmetry transformation
associated with the central charge and the energy-momentum tensor to one-loop
order.Comment: 8 pages, LaTe
Time complexity and gate complexity
We formulate and investigate the simplest version of time-optimal quantum
computation theory (t-QCT), where the computation time is defined by the
physical one and the Hamiltonian contains only one- and two-qubit interactions.
This version of t-QCT is also considered as optimality by sub-Riemannian
geodesic length. The work has two aims: one is to develop a t-QCT itself based
on physically natural concept of time, and the other is to pursue the
possibility of using t-QCT as a tool to estimate the complexity in conventional
gate-optimal quantum computation theory (g-QCT). In particular, we investigate
to what extent is true the statement: time complexity is polynomial in the
number of qubits if and only if so is gate complexity. In the analysis, we
relate t-QCT and optimal control theory (OCT) through fidelity-optimal
computation theory (f-QCT); f-QCT is equivalent to t-QCT in the limit of unit
optimal fidelity, while it is formally similar to OCT. We then develop an
efficient numerical scheme for f-QCT by modifying Krotov's method in OCT, which
has monotonic convergence property. We implemented the scheme and obtained
solutions of f-QCT and of t-QCT for the quantum Fourier transform and a unitary
operator that does not have an apparent symmetry. The former has a polynomial
gate complexity and the latter is expected to have exponential one because a
series of generic unitary operators has a exponential gate complexity. The time
complexity for the former is found to be linear in the number of qubits, which
is understood naturally by the existence of an upper bound. The time complexity
for the latter is exponential. Thus the both targets are examples satisfyng the
statement above. The typical characteristics of the optimal Hamiltonians are
symmetry under time-reversal and constancy of one-qubit operation, which are
mathematically shown to hold in fairly general situations.Comment: 11 pages, 6 figure
Critical Exponents and Stability at the Black Hole Threshold for a Complex Scalar Field
This paper continues a study on Choptuik scaling in gravitational collapse of
a complex scalar field at the threshold for black hole formation. We perform a
linear perturbation analysis of the previously derived complex critical
solution, and calculate the critical exponent for black hole mass, . We also show that this critical solution is unstable via a
growing oscillatory mode.Comment: 15 pages of latex/revtex; added details of numerics, in press in Phys
Rev D; 1 figure included, or available by anonymous ftp to
ftp://ftp.itp.ucsb.edu/figures/nsf-itp-95-58.ep
Domestic use of biomass fuel in the rural Meghna floodplain areas of Bangladesh
Rural households in the developing countries constitute the largest share of the biomass fuel consumption. It is also a major source of energy in the low income country. However, this energy consumption pattern varies from region to region. Different case studies on the biomass fuel consumption will certainly contribute to the understanding on the energy uses of a nation. The present study was conducted in the rural areas of the Meghna floodplain zone in Bangladesh, with a total of 80 sampled households, using the stratified random sampling technique through the semi-structured questionnaires from November 2008 through February 2009. Firewood, cowdung, leaves and twigs, branches, rice straw and rice husk were used as the biomass fuels mainly for the cooking purpose. Leaves and twigs were found as the dominant biomass fuel as 187 +/- 25.69 (SE) kg month(-1) household(-1). The major source of biomass fuel collection was identified as the own homestead and agricultural lands, 74%. The households spent 14.56 +/- 8.94 US$ month(-1) household(-1) for biomass fuels. The ratio of the total energy expenditure to the total income of the household was around 11%. But, the ratio of the biomass expenditure to the total energy expenditure of the households was 68%. Monthly income, land ownership and family size were found significantly influencing to the biomass energy expenditure. The study will be useful for the policy makers in the renewable energy, forestry and agriculture sector in Bangladesh.ArticleIFOREST-BIOGEOSCIENCES AND FORESTRY. 3:144-149 (2010)journal articl
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