3,363 research outputs found
Neutrino Processes in Strong Magnetic Fields
The processes of electron neutrino capture on neutron and electron
anti-neutrino capture on proton, and their reverse processes provide the
dominant mechanisms for heating and cooling the material below the stalled
shock in a core-collapse supernova. We summarize the major effects of strong
magnetic fields on the rates of the above reactions and illustrate these
effects with a simple supernova model. Due to parity violation of weak
interaction the heating rates are asymmetric even for a uniform magnetic field.
The cooling rates are also asymmetric for nonuniform fields. The most dramatic
effect of strong magnetic fields of 10^16 G is suppression of the cooling rates
by changing the equations of state through the phase space of electrons and
positrons.Comment: 10 pages, 4 figures, talk given at INT workshop "Open Issues in
Understanding Core Collapse Supernovae," Seattle, June 200
Phononic topological insulators with tunable pseudospin physics
Efficient control of phonons is crucial to energy-information technology, but
limited by the lacking of tunable degrees of freedom like charge or spin. Here
we suggest to utilize crystalline symmetry-protected pseudospins as new quantum
degrees of freedom to manipulate phonons. Remarkably, we reveal a duality
between phonon pseudospins and electron spins by presenting Kramers-like
degeneracy and pseudospin counterparts of spin-orbit coupling, which lays the
foundation for "pseudospin phononics". Furthermore, we report two types of
three-dimensional phononic topological insulators, which give topologically
protected, gapless surface states with linear and quadratic band degeneracies,
respectively. These topological surface states display unconventional phonon
transport behaviors attributed to the unique pseudospin-momentum locking, which
are useful for phononic circuits, transistors, antennas, etc. The emerging
pseudospin physics offers new opportunities to develop future phononics
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