303,770 research outputs found
Hot spin spots in the laser-induced demagnetization
Laser-induced femtosecond magnetism or femtomagnetism simultaneously relies
on two distinctive contributions: (a) the optical dipole interaction (ODI)
between a laser field and a magnetic system and (b) the spin expectation value
change (SEC) between two transition states. Surprisingly, up to now, no study
has taken both contributions into account simultaneously. Here we do so by
introducing a new concept of the optical spin generator, a product of SEC and
ODI between transition states. In ferromagnetic nickel, our first-principles
calculation demonstrates that the larger the value of optical spin generator
is, the larger the dynamic spin moment change is. This simple generator
directly links the time-dependent spin moment change {\Delta}Mk z (t) at every
crystal- momentum k point to its intrinsic electronic structure and magnetic
properties. Those hot spin spots are a direct manifestation of the optical spin
generator, and should be the focus of future research.Comment: 10 pages, 2 figures, [email protected]
Displaced vertex signatures of doubly charged scalars in the type-II seesaw and its left-right extensions
The type-II seesaw mechanism with an isospin-triplet scalar
provides one of the most compelling explanations for the observed smallness of
neutrino masses. The triplet contains a doubly-charged component
, which dominantly decays to either same-sign dileptons or to a
pair of bosons, depending on the size of the triplet vacuum expectation
value. However, there exists a range of Yukawa couplings of the triplet
to the charged leptons, wherein a relatively light tends to be
long-lived, giving rise to distinct displaced-vertex signatures at the
high-energy colliders. We find that the displaced vertex signals from the
leptonic decays could probe a
broad parameter space with and 45.6
GeV GeV at the high-luminosity LHC. Similar
sensitivity can also be achieved at a future 1 TeV collider. The mass
reach can be extended to about 500 GeV at a future 100 TeV proton-proton
collider. Similar conclusions apply for the right-handed triplet
in the TeV-scale left-right symmetric models, which provide a natural embedding
of the type-II seesaw. We show that the displaced vertex signals are largely
complementary to the prompt same-sign dilepton pair searches at the LHC and the
low-energy, high-intensity/precision measurements, such as neutrinoless double
beta decay, charged lepton flavor violation, electron and muon anomalous
magnetic moments, muonium oscillation and M{\o}ller scattering.Comment: 49 pages, 25 figures and 2 tables, minor changes, version to appear
in JHE
Experimental and theoretical study of artificial plasma layers produced by two intersecting beams in a chamber
The work done on the Bragg scattering of electromagnetic waves by microwave produced plasma layers is reported. Also summarized is the work accomplished on the propagation of high power microwave pulses in an air breakdown environment. Ongoing work on the theoretical model and numerical results of pulse propagation in air is also presented as are the results of studying the decay of plasma density and temperature
Octupole degree of freedom for the critical-point candidate nucleus Sm in a reflection-asymmetric relativistic mean-field approach
The potential energy surfaces of even-even Sm are investigated in
the constrained reflection-asymmetric relativistic mean-field approach with
parameter set PK1. It is shown that the critical-point candidate nucleus
Sm marks the shape/phase transition not only from U(5) to SU(3)
symmetry, but also from the octupole-deformed ground state in Sm to the
quadrupole-deformed ground state in Sm. By including the octupole
degree of freedom, an energy gap near the Fermi surface for single-particle
levels in Sm with is found, and the
important role of the octupole deformation driving pair and is demonstrated.Comment: 11 pages, 3 figure
The Picard group of the loop space of the Riemann sphere
The loop space of the Riemann sphere consisting of all C^k or Sobolev W^{k,p}
maps from the circle S^1 to the sphere is an infinite dimensional complex
manifold. We compute the Picard group of holomorphic line bundles on this loop
space as an infinite dimensional complex Lie group with Lie algebra the first
Dolbeault group. The group of Mobius transformations G and its loop group LG
act on this loop space. We prove that an element of the Picard group is
LG-fixed if it is G-fixed; thus completely answer the question by Millson and
Zombro about G-equivariant projective embedding of the loop space of the
Riemann sphere.Comment: International Journal of Mathematic
Controlled splitting of an atomic wave packet
We propose a simple scheme capable of adiabatically splitting an atomic wave
packet using two independent translating traps. Implemented with optical dipole
traps, our scheme allows a high degree of flexibility for atom interferometry
arrangements and highlights its potential as an efficient and high fidelity
atom optical beam splitter.Comment: 4 pages, 4 figures. Accepted by Phys. Rev. Let
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