1,987 research outputs found
Dynamics of Ferromagnetic Walls: Gravitational Properties
We discuss a new mechanism which allows domain walls produced during the
primordial electroweak phase transition. We show that the effective surface
tension of these domain walls can be made vanishingly small due to a peculiar
magnetic condensation induced by fermion zero modes localized on the wall. We
find that in the perfect gas approximation the domain wall network behaves like
a radiation gas. We consider the recent high-red shift supernova data and we
find that the corresponding Hubble diagram is compatible with the presence in
the Universe of a ideal gas of ferromagnetic domain walls. We show that our
domain wall gas induces a completely negligible contribution to the large-scale
anisotropy of the microwave background radiation.Comment: Replaced with revised version, accepted for publication in IJMP
Dependence of nuclear magnetic moments on quark masses and limits on temporal variation of fundamental constants from atomic clock experiments
We calculate the dependence of the nuclear magnetic moments on the quark
masses including the spin-spin interaction effects and obtain limits on the
variation of the fine structure constant and
using recent atomic clock experiments examining hyperfine transitions in H, Rb,
Cs, Yb and Hg and the optical transition in H, Hg and Yb
A remark on the BRST symmetry in the Gribov-Zwanziger theory
We show that the soft breaking of the BRST symmetry arising in the
Gribov-Zwanziger theory can be converted into a linear breaking upon
introduction of a set of BRST quartets of auxiliary fields. Due to its
compatibility with the Quantum Action Principle, the linearly broken BRST
symmetry can be directly converted into a suitable set of useful Slavnov-Taylor
identities. As a consequence, it turns out that the renormalization aspects of
the Gribov-Zwanziger theory can be addressed by means of the cohomology of a
nilpotent local operatorComment: 11 pages, final version to appear in Phys. Rev.
Cosmic Parallax in Ellipsoidal Universe
The detection of a time variation of the angle between two distant sources
would reveal an anisotropic expansion of the Universe. We study this effect of
"cosmic parallax" within the "ellipsoidal universe" model, namely a particular
homogeneous anisotropic cosmological model of Bianchi type I, whose attractive
feature is the potentiality to account for the observed lack of power of the
large-scale cosmic microwave background anisotropy. The preferred direction in
the sky, singled out by the axis of symmetry inherent to planar symmetry of
ellipsoidal universe, could in principle be constrained by future cosmic
parallax data. However, that will be a real possibility if and when the
experimental accuracy will be enhanced at least by two orders of magnitude.Comment: 9 pages, 2 figures, 1 table. Revised version to match published
version. References adde
Influence of the Magnetic Field on the Fermion Scattering off Bubble and Kink Walls
We investigate the scattering of fermions off domain walls at the electroweak
phase transition in presence of a magnetic field. We consider both the bubble
wall and the kink domain wall. We derive and solve the Dirac equation for
fermions with momentum perpendicular to the walls, and compute the transmission
and reflection coefficients. In the case of kink domain wall, we briefly
discuss the zero mode solutions localized on the wall. The possibile role of
the magnetic field for the electroweak baryogenesis is also discussed.Comment: 11 pages and 3 eps figure
Simultaneous recording of electrical and metabolic activity of cardiac cells in vitro using an organic charge modulated field effect transistor array
In vitro electrogenic cells monitoring is an important objective in several scientific and technological fields, such as electrophysiology, pharmacology and brain machine interfaces, and can represent an interesting opportunity in other translational medicine applications. One of the key aspects of cellular cultures is the complexity of their behavior, due to the different kinds of bio-related signals, both chemical and electrical, that characterize these systems. In order to fully understand and exploit this extraordinary complexity, specific devices and tools are needed. However, at the moment this important scientific field is characterized by the lack of easy-to-use, low-cost devices for the sensing of multiple cellular parameters. To the aim of providing a simple and integrated approach for the study of in vitro electrogenic cultures, we present here a new solution for the monitoring of both the electrical and the metabolic cellular activity. In particular, we show here how a particular device called Micro Organic Charge Modulated Array (MOA) can be conveniently engineered and then used to simultaneously record the complete cell activity using the same device architecture. The system has been tested using primary cardiac rat myocytes and allowed to detect the metabolic and electrical variations thar occur upon the administration of different drugs. This first example could lay the basis for the development of a new generation of multi-sensing tools that can help to efficiently probe the multifaceted in vitro environment
Renormalizability of the linearly broken formulation of the BRST symmetry in presence of the Gribov horizon in Landau gauge Euclidean Yang-Mills theories
In previous work arXiv:1009.4135 we have shown that the soft breaking of the
BRST symmetry arising within the Gribov-Zwanziger framework can be converted
into a linear breaking, while preserving the nilpotency of the BRST operator.
Due to its compatibility with the Quantum Action Principle, the linearly broken
BRST symmetry directly translates into a set of Slavnov-Taylor identities. We
show that these identities guarantee the multiplicative renormalizability of
both Gribov-Zwanziger and Refined Gribov-Zwanziger theories to all orders. The
known property that only two renormalization factors are needed is recovered.
The non-renormalization theorem of the gluon-ghost-antighost vertex as well as
the renormalization factor of the Gribov parameter are derived within the
linearly broken formulation.Comment: 20 pages, references added, version accepted for publication in
Physical Review
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