8,698 research outputs found
Two-loop free energy of three-dimensional antiferromagnets in external magnetic and staggered fields
Using a model-independent low-energy effective field theory, we calculate the
free energy of three-dimensional antiferromagnets in a combination of mutually
perpendicular external magnetic and staggered fields at the
next-to-next-to-leading, two-loop order. Renormalization is carried out
analytically, and the renormalization group invariance of the result is checked
explicitly. The free energy is thus expressed solely in terms of temperature,
the external fields, and a set of low-energy coupling constants, to be
determined by experiment or by matching to the microscopic model of a given
concrete material.Comment: 19 page
2D-Oide effect
The Oide effect considers the synchrotron radiation in the final focusing
quadrupole and it sets a lower limit on the vertical beam size at the
Interaction Point, particularly relevant for high energy linear colliders. The
theory of the Oide effect was derived considering only the radiation in the
focusing plane of the magnet. This article addresses the theoretical
calculation of the radiation effect on the beam size consider- ing both
focusing and defocusing planes of the quadrupole, refered to as 2D-Oide. The
CLIC 3 TeV final quadrupole (QD0) and beam parameters are used to compare the
theoretical results from the Oide effect and the 2D-Oide effect with particle
tracking in PLACET. The 2D-oide demonstrates to be important as it increases by
17% the contribution to the beam size. Further insight into the aberrations
induced by the synchrotron radiation opens the possibility to partially correct
the 2D-Oide effect with octupole mag
Towards a More Articulated and Relevant System of National Accounts
This article is part of the NEDA-PIDS Seminar-Workshop on the Philippine System of National Accounts. It reports what has been achieved after the last workshop held last November 1976. It also discusses the more pressing problems and issues relating to the balance of payment and government financial statistics.balance of payments, data and statistics, national account
Towards a More Articulated and Relevant System of National Accounts
This article is part of the NEDA-PIDS Seminar-Workshop on the Philippine System of National Accounts. It reports what has been achieved after the last workshop held last November 1976. It also discusses the more pressing problems and issues relating to the balance of payment and government financial statistics.balance of payments, data and statistics, national account
Current and current fluctuations in quantum shuttles
We review the properties of electron shuttles, i.e. nanoelectromechanical
devices that transport electrons one-by-one by utilizing a combination of
electronic and mechanical degrees of freedom. We focus on the extreme quantum
limit, where the mechanical motion is quantized. We introduce the main
theoretical tools needed for the analysis, e.g. generalized master equations
and Wigner functions, and we outline the methods how the resulting large
numerical problems can be handled. Illustrative results are given for current,
noise, and full counting statistics for a number of model systems. Throughout
the review we focus on the physics behind the various approximations, and some
simple examples are given to illustrate the theoretical concepts. We also
comment on the experimental situation.Comment: Minireview; technical level aimed at general audience, based on an
invited talk at "Transport Phenomena in Micro and Nanodevices", October 17-21
Kona, Hawai
Light Nuclei in the Framework of the Symplectic No-core Shell Model
A symplectic no-core shell model (Sp-NCSM) is constructed with the goal of
extending the {\it ab-initio} NCSM to include strongly deformed
higher-oscillator-shell configurations and to reach heavier nuclei that cannot
be studied currently because the spaces encountered are too large to handle,
even with the best of modern-day computers. This goal is achieved by
integrating two powerful concepts: the {\it ab-initio} NCSM with that of the
group-theoretical approach.
The NCSM uses modern realistic nuclear interactions in model spaces that
consists of many-body configurations up to a given number of
excitations together with modern high-performance parallel computing
techniques. The symplectic theory extends this picture by recognizing that when
deformed configurations dominate, which they often do, the model space can be
better selected so less relevant low-lying configurations yield
to more relevant high-lying configurations, ones that respect a
near symplectic symmetry found in the Hamiltonian. Results from an application
of the Sp-NCSM to light nuclei are compared with those for the NCSM and with
experiment.Comment: 9 pages, 3 figures, Proceedings of the XXV International Workshop on
Nuclear Theory, June 26-July 1, 2006, Rila Mountains, Bulgari
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