1,853 research outputs found
Theory of magnetoelectric photocurrent generated by direct interband transitions in semiconductor quantum well
A linearly polarized light normally incident on a semiconductor quantum well
with spin-orbit coupling may generate pure spin current via direct interband
optical transition. An electric photocurrent can be extracted from the pure
spin current when an in-plane magnetic field is applied, which has been
recently observed in the InGaAs/InAlAs quantum well [Dai et al., Phys. Rev.
Lett. 104, 246601 (2010)]. Here we present a theoretical study of this
magnetoelectric photocurrent effect associated with the interband transition.
By employing the density matrix formalism, we show that the photoexcited
carrier density has an anisotropic distribution in k space, strongly dependent
on the orientation of the electron wavevector and the polarization of the
light. This anisotropy provides an intuitive picture of the observed dependence
of the photocurrent on the magnetic field and the polarization of the light. We
also show that the ratio of the pure spin photocurrent to the magnetoelectric
photocurrent is approximately equal to the ratio of the kinetic energy to the
Zeeman energy, which enables us to estimate the magnitude of the pure spin
photocurrent. The photocurrent density calculated with the help of an
anisotropic Rashba model and the Kohn-Luttinger model can produce all three
terms in the fitting formula for measured current, with comparable order of
magnitude, but discrepancies are still present and further investigation is
needed.Comment: 13 pages, 9 figures, 2 table
The naturalness in the BLMSSM and B-LSSM
In order to interpret the Higgs mass and its decays more naturally, we hope
to intrude the BLMSSM and B-LSSM. In the both models, the right-handed neutrino
superfields are introduced to better explain the neutrino mass problems. In
addition, there are other superfields considered to make these models more
natural than MSSM. In this paper, the method of analyses will be
adopted in the BLMSSM and B-LSSM to calculate the Higgs mass, Higgs decays and
muon . With the fine-tuning in the region and ,
we can obtain the reasonable theoretical values that are in accordance with the
experimental results respectively in the BLMSSM and B-LSSM. Meanwhile, the
best-fitted benchmark points in the BLMSSM and B-LSSM will be acquired at
minimal and ,
respectively
Transition magnetic moment of Majorana neutrinos in the SSM
The nonzero vacuum expectative values of sneutrinos induce spontaneously
R-parity and lepton number violation, and generate three tiny Majorana neutrino
masses through the seesaw mechanism in the SSM, which is one of
Supersymmetric extensions beyond Standard Model. Applying effective Lagrangian
method, we study the transition magnetic moment of Majorana neutrinos in the
model here. Under the constraints from neutrino oscillations, we consider the
two possibilities on the neutrino mass spectrum with normal or inverted
ordering.Comment: 20 pages, 2 figures, accepted for publication in JHEP. arXiv admin
note: text overlap with arXiv:1305.4352, arXiv:1304.624
GKZ hypergeometric systems of the three-loop vacuum Feynman integrals
We present the Gel'fand-Kapranov-Zelevinsky (GKZ) hypergeometric systems of
the Feynman integrals of the three-loop vacuum diagrams with arbitrary masses,
basing on Mellin-Barnes representations and Miller's transformation. The
codimension of derived GKZ hypergeometric systems equals the number of
independent dimensionless ratios among the virtual masses squared. Through GKZ
hypergeometric systems, the analytical hypergeometric series solutions can be
obtained in neighborhoods of origin including infinity. The linear independent
hypergeometric series solutions whose convergent regions have non-empty
intersection can constitute a fundamental solution system in a proper subset of
the whole parameter space. The analytical expression of the vacuum integral can
be formulated as a linear combination of the corresponding fundamental solution
system in certain convergent region.Comment: 47 pages, 2 figures. arXiv admin note: text overlap with
arXiv:2209.1519
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