3,824 research outputs found
Particle-Number Projected Hartree-Fock-Bogoliubov Study with Effective Shell Model Interactions
We perform particle-number projected mean-field study using the recently
developed symmetry-projected Hartree-Fock-Bogoliubov (HFB) equations. Realistic
calculations have been performed in sd- and fp-shell nuclei using the shell
model empirical intearctions, USD and GXPFIA. It is demonstrated that the
mean-field results for energy surfaces, obtained with these shell model
interactions, are quite similar to those obtained using the density functional
approaches. Further, it is shown that particle-number projected results, for
neutron rich isotopes, can lead to different ground-state shapes in comparison
to the bare HFB calculations.Comment: 10 page
Competition of different coupling schemes in atomic nuclei
Shell model calculations reveal that the ground and low-lying yrast states of
the nuclei Pd and Cd are mainly built upon isoscalar
spin-aligned neutron-proton pairs each carrying the maximum angular momentum
J=9 allowed by the shell which is dominant in this nuclear region.
This mode of excitation is unique in nuclei and indicates that the spin-aligned
pair has to be considered as an essential building block in nuclear structure
calculations. In this contribution we will discuss this neutron-proton pair
coupling scheme in detail. In particular, we will explore the competition
between the normal monopole pair coupling and the spin-aligned coupling
schemes. Such a coupling may be useful in elucidating the structure properties
of and neighboring nuclei.Comment: 10 pages, 7 figures, 1 table. Proceedings of the Conference on
Advanced Many-Body and Statistical Methods in Mesoscopic Systems, Constanta,
Romania, June 27th - July 2nd 2011. To appear in Journal of Physics:
Conference Serie
Building the field of health policy and systems research: framing the questions.
In the first of a series of articles addressing the current challenges and opportunities for the development of Health Policy & Systems Research (HPSR), Kabir Sheikh and colleagues lay out the main questions vexing the field
Classification of All 1/2 BPS Solutions of the Tiny Graviton Matrix Theory
The tiny graviton matrix theory [hep-th/0406214] is proposed to describe DLCQ
of type IIB string theory on the maximally supersymmetric plane-wave or
AdS_5xS^5 background. In this paper we provide further evidence in support of
the tiny graviton conjecture by focusing on the zero energy, half BPS
configurations of this matrix theory and classify all of them. These vacua are
generically of the form of various three sphere giant gravitons. We clarify the
connection between our solutions and the half BPS configuration in N=4 SYM
theory and their gravity duals. Moreover, using our half BPS solutions, we show
how the tiny graviton Matrix theory and the mass deformed D=3, N=8
superconformal field theories are related to each other.Comment: 40 pages, 12 figures, v
High-Spin Doublet Band Structures in odd-odd Tl isotopes
The basis space in the triaxial projected shell model (TPSM) approach is
generalized for odd-odd nuclei to include two-neutron and two-proton
configurations on the basic one-neutron coupled to one-proton quasiparticle
state. The generalization allows to investigate odd-odd nuclei beyond the band
crossing region and as a first application of this development, high-spin band
structures recently observed in odd-odd Tl isotopes are
investigated. In some of these isotopes, the doublet band structures observed
after the band crossing have been conjectured to arise from the spontaneous
breaking of the chiral symmetry. The driving configuration of the chiral
symmetry in these odd-odd isotopes is one-proton and three-neutrons rather than
the basic one-proton and one-neutron as already observed in many other nuclei.
It is demonstrated using the TPSM approach that energy differences of the
doublet bands in Tl and Tl are, indeed, small. However, the
differences in the calculated transition probabilities are somewhat larger than
what is expected in the chiral symmetry limit. Experimental data on the
transition probabilities is needed to shed light on the chiral nature of the
doublet bands.Comment: 11 pages, 17 figures, to appear in EPJ
Compton scattering in Noncommutative Space-Time at the NLC
We study the Compton scattering in the noncommutative counter part of QED (NC
QED). Interactions in NC QED have momentum dependent phase factors and the
gauge fields have Yang Mills type couplings, this modifies the cross sections
and are different from the commuting Standard Model. Collider signals of
noncommutative space-time are studied at the Next Linear Collider (NLC)
operating in the mode. Results for different polarised cases are
presented and it is shown that the Compton process can probe the noncommutative
scale in the range of 1 - 2.5 TeV for typical proposed NLC energies.Comment: 12 pages, 5 Postscript figures, version to appear in Phys. Rev.
Hamiltonian embedding of the massive noncommutative U(1) theory
We show that the massive noncommutative U(1) can be embedded in a gauge
theory by using the BFFT Hamiltonian formalism. By virtue of the peculiar
non-Abelian algebraic structure of the noncommutative massive U(1) theory,
several specific identities involving Moyal commutators had to be used in order
to make the embedding possible. This leads to an infinite number of steps in
the iterative process of obtaining first-class constraints. We also shown that
the involutive Hamiltonian can be constructed.Comment: 8 pages, Revtex (multicol
Signals for Non-Commutative Interactions at Linear Colliders
Recent theoretical results have demonstrated that non-commutative geometries
naturally appear within the context of string/M-theory. One consequence of this
possibility is that QED takes on a non-abelian nature due to the introduction
of 3- and 4-point functions. In addition, each QED vertex acquires a momentum
dependent phase factor. We parameterize the effects of non-commutative
space-time co-ordinates and show that they lead to observable signatures in
several QED processes in collisions. In particular, we
examine pair annihilation, Moller and Bhabha scattering, as well as
scattering and show that non-commutative scales
of order a TeV can be probed at high energy linear colliders.Comment: 51 pages, 23 figures, typos corrected, figure and references adde
and colliding in noncommutative space
By studying the scattering process of scalar particle pion on the
noncommutative scalar quantum electrodynamics, the non-commutative amendment of
differential scattering cross-section is found, which is dependent of
polar-angle and the results are significantly different from that in the
commutative scalar quantum electrodynamics, particularly when . The non-commutativity of space is expected to be explored at around
TeV.Comment: Latex, 12 page
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