2,798 research outputs found
Li in a Three-Body Model with Realistic Forces: Separable vs. Non-separable Approach
{\bf Background:} Deuteron induced reactions are widely used to probe nuclear
structure and astrophysical information. Those (d,p) reactions may be viewed as
three-body reactions and described with Faddeev techniques.
{\bf Purpose:} Faddeev equations in momentum space have a long tradition of
utilizing separable interactions in order to arrive at sets of coupled integral
equations in one variable. However, it needs to be demonstrated that their
solution based on separable interactions agrees exactly with solutions based on
non-separable forces.
{\bf Results:} The ground state of Li is calculated via momentum space
Faddeev equations using the CD-Bonn neutron-proton force and a Woods-Saxon type
neutron(proton)-He force. For the latter the Pauli-forbidden -wave bound
state is projected out. This result is compared to a calculation in which the
interactions in the two-body subsystems are represented by separable
interactions derived in the Ernst-Shakin-Thaler framework.
{\bf Conclusions:} We find that calculations based on the separable
representation of the interactions and the original interactions give results
that agree to four significant figures for the binding energy, provided an
off-shell extension of the EST representation is employed in both subsystems.
The momentum distributions computed in both approaches also fully agree with
each other
Entry times in automata with simple defect dynamics
In this paper, we consider a simple cellular automaton with two particles of
different speeds that annihilate on contact. Following a previous work by K\r
urka et al., we study the asymptotic distribution, starting from a random
configuration, of the waiting time before a particle crosses the central column
after time n. Drawing a parallel between the behaviour of this automata on a
random initial configuration and a certain random walk, we approximate this
walk using a Brownian motion, and we obtain explicit results for a wide class
of initial measures and other automata with similar dynamics.Comment: In Proceedings AUTOMATA&JAC 2012, arXiv:1208.249
Importance of initial and final states as intermediate states in two-photon spectroscopy of polar molecules
Two-photon transitions may proceed via a mechanism not involving virtually excited intermediate states. This mechanism may account for the largest contribution to the 2-photon cross section in polar mols. if the dipole moment strongly alters with excitation. Possible consequences for the 2-photon detection of forbidden states in polar polyene systems are discussed
Orientifolds, RR Torsion, and K-theory
We analyze the role of RR fluxes in orientifold backgrounds from the point of
view of K-theory, and demonstrate some physical implications of describing
these fluxes in K-theory rather than cohomology. In particular, we show that
certain fractional shifts in RR charge quantization due to discrete RR fluxes
are naturally explained in K-theory. We also show that some orientifold
backgrounds, which are considered distinct in the cohomology classification,
become equivalent in the K-theory description, while others become unphysical.Comment: 30 pages, 5 figures; typos corrected and references adde
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