922 research outputs found
Fermion Condensate and Vacuum Current Density Induced by Homogeneous and Inhomogeneous Magnetic Fields in (2+1)-Dimensions
We calculate the condensate and the vacuum current density induced by
external static magnetic fields in (2+1)-dimensions. At the perturbative level,
we consider an exponentially decaying magnetic field along one cartesian
coordinate. Non-perturbatively, we obtain the fermion propagator in the
presence of a uniform magnetic field by solving the Schwinger-Dyson equation in
the rainbow-ladder approximation. In the large flux limit, we observe that both
these quantities, either perturbative (inhomogeneous) and non-perturbative
(homogeneous), are proportional to the external field, in agreement with early
expectations.Comment: 8 pages, 2 figures. Accepted for publication in Phys. Rev.
Massive Dirac fermions and the zero field quantum Hall effect
Through an explicit calculation for a Lagrangian in quantum electrodynamics
in (2+1)-space--time dimensions (QED), making use of the relativistic Kubo
formula, we demonstrate that the filling factor accompanying the quantized
electrical conductivity for massive Dirac fermions of a single species in two
spatial dimensions is a half (in natural units) when time reversal and parity
symmetries of the Lagrangian are explicitly broken by the fermion mass term. We
then discuss the most general form of the QED Lagrangian, both for
irreducible and reducible representations of the Dirac matrices in the plane,
with emphasis on the appearance of a Chern-Simons term. We also identify the
value of the filling factor with a zero field quantum Hall effect (QHE).Comment: 15 pages. Accepted in Jour. Phys.
Analisis Kewajiban Deposito sebagai Jaminan Reklamasi dan Pascatambang
Sesuai dengan Undang-Undang Nomor 32 Tahun 2009 tentang Perlindungan dan Pengelolaan Lingkungan Hidup menyebutkan bahwa dalam rangka melestarikan fungsi lingkungan hidup, maka setiap orang wajib untuk melindungi lingkungan. Undang-Undang Nomor 4 tahun 2009 tentang Mineral dan Batubara, mengatur mengenai izin USAha pertambangan. Perusahaan diwajibkan menyetor deposito untuk menjamin reklamasi dan pascatambang. Objek tulisan ini terkait dengan kewajiban deposito sebagai jaminan reklamasi dan pascatambang, dengan menggunakan metode yuridis normatif. Hasil penelitian menunjukkan bahwa setiap Perusahaan diwajibkan melakukan kegiatan pertambangan agar dapat melestarikan fungsi lingkungan hidup dan mencegah terjadinya pencemaran dan/ atau kerusakan lingkungan
Chiral and Parity Symmetry Breaking for Planar Fermions: Effects of a Heat Bath and Uniform External Magnetic Field
We study chiral symmetry breaking for relativistic fermions, described by a
parity violating Lagrangian in 2+1-dimensions, in the presence of a heat bath
and a uniform external magnetic field. Working within their four-component
formalism allows for the inclusion of both parity-even and -odd mass terms.
Therefore, we can define two types of fermion anti-fermion condensates. For a
given value of the magnetic field, there exist two different critical
temperatures which would render one of these condensates identically zero,
while the other would survive. Our analysis is completely general: it requires
no particular simplifying hierarchy among the energy scales involved, namely,
bare masses, field strength and temperature. However, we do reproduce some
earlier results, obtained or anticipated in literature, corresponding to
special kinematical regimes for the parity conserving case. Relating the chiral
condensate to the one-loop effective Lagrangian, we also obtain the
magnetization and the pair production rate for different fermion species in a
uniform electric field through the replacement .Comment: 9 pages, 10 figure
Free Form of the Foldy-Wouthuysen Transformation in External Electromagnetic Fields
We derive the exact Foldy-Wouthuysen transformation for Dirac fermions in a
time independent external electromagnetic field in the basis of the Ritus
eigenfunctions, namely the eigenfunctions of the operator , with . In this basis, the transformation
acquires a free form involving the dynamical quantum numbers induced by the
field.Comment: 8 pages. Accepted in J. Phys. A: Math. and Theo. (Fast Track
Communication
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