126 research outputs found
The tensor Goldstone multiplet for partially broken supersymmetry
We show that the tensor gauge multiplet of N=1 supersymmetry can serve as the
Goldstone multiplet for partially broken rigid N=2 supersymmetry. We exploit a
remarkable analogy with the Goldstone-Maxwell multiplet of hep-th/9608177 to
find its nonlinear transformation law and its invariant Goldstone action. We
demonstrate that the tensor multiplet has two dualities. The first transforms
it into the chiral Goldstone multiplet; the other leaves it invariant.Comment: 7 pages, Latex. Expanded discussion of duality symmetrie
New Goldstone multiplet for partially broken supersymmetry
The partial spontaneous breaking of rigid N=2 supersymmetry implies the
existence of a massless N=1 Goldstone multiplet. In this paper we show that the
spin-(1/2,1) Maxwell multiplet can play this role. We construct its full
nonlinear transformation law and find the invariant Goldstone action. The
spin-1 piece of the action turns out to be of Born-Infeld type, and the full
superfield action is duality invariant. This leads us to conclude that the
Goldstone multiplet can be associated with a D-brane solution of superstring
theory for p=3. In addition, we find that N=1 chirality is preserved in the
presence of the Goldstone-Maxwell multiplet. This allows us to couple it to N=1
chiral and gauge field multiplets. We find that arbitrary Kahler and
superpotentials are consistent with partially broken N=2 supersymmetry.Comment: Latex, 13 pages. Version to appear in Phys. Rev.
General Determination of Phases in Leptonic Mass Matrices
We construct new invariants and give several theorems which determine in
general (i) the number of physically meaningful phases in charged lepton and
neutrino mass matrices and (ii) which elements of these matrices can be
rendered real by rephasings. We illustrate our results with simple models.Comment: 11 pages, ITP-SB-93-63, late
Recommended from our members
Steering carbon dioxide reduction toward CâC coupling using copper electrodes modified with porous molecular films
Copper offers unique capability as catalyst for multicarbon compounds production in the electrochemical carbon dioxide reduction reaction. In lieu of conventional catalysis alloying with other elements, copper can be modified with organic molecules to regulate product distribution. Here, we systematically study to which extent the carbon dioxide reduction is affected by film thickness and porosity. On a polycrystalline copper electrode, immobilization of porous bipyridine-based films of varying thicknesses is shown to result in almost an order of magnitude enhancement of the intrinsic current density pertaining to ethylene formation while multicarbon products selectivity increases from 9.7 to 61.9%. In contrast, the total current density remains mostly unaffected by the modification once it is normalized with respect to the electrochemical active surface area. Supported by a microkinetic model, we propose that porous and thick films increase both local carbon monoxide partial pressure and the carbon monoxide surface coverage by retaining in situ generated carbon monoxide. This reroutes the reaction pathway toward multicarbon products by enhancing carbonâcarbon coupling. Our study highlights the significance of customizing the molecular film structure to improve the selectivity of copper catalysts for carbon dioxide reduction reaction
1<i>s</i>2<i>p</i> resonant inelastic X-ray scattering combined dipole and quadrupole analysis method
In this study an analysis strategy towards using the resonant inelastic X-ray scattering (RIXS) technique more effectively compared with X-ray absorption spectroscopy (XAS) is presented. In particular, the question of when RIXS brings extra information compared with XAS is addressed. To answer this question the RIXS plane is analysed using two models: (i) an exciton model and (ii) a continuum model. The continuum model describes the dipole pre-edge excitations while the exciton model describes the quadrupole excitations. Applying our approach to the experimental 1s2p RIXS planes of VO2 and TiO2, it is shown that only in the case of quadrupole excitations being present is additional information gained by RIXS compared with XAS. Combining this knowledge with methods to calculate the dipole contribution in XAS measurements gives scientists the opportunity to plan more effective experiments.</jats:p
(B-L) Symmetry vs. Neutrino Seesaw
We compute the effective coupling of the Majoron to W bosons at \cO(\hbar)
by evaluating the matrix element of the (B-L) current between the vacuum and a
state. The (B-L) anomaly vanishes, but the amplitude does not vanish
as a result of a UV finite and non-local contribution which is entirely due to
the mixing between left-chiral and right-chiral neutrinos. The result shows how
anomaly-like couplings may arise in spite of the fact that the (B-L) current
remains exactly conserved to all orders in , lending additional support
to our previous proposal to identify the Majoron with the axion.Comment: 13 pages, 1 figure, with additional explanations and clarification
Constraints on Supersymmetric Models from the Muon Anomalous Magnetic Moment
We study the impact of present and future measurements on
supersymmetric models. The corrections to become particularly
relevant in the presence of light sleptons, charginos and neutralinos,
especially in the large regime. For moderate or large values of
, it is possible to rule out scenarios in which charginos and
sneutrinos are both light, but nevertheless escape detection at the LEP2
collider. Furthermore, models in which supersymmetry breaking is transferred to
the observable sector through gauge interactions can be efficiently constrained
by the measurement.Comment: 15 pages, 4 figures, Late
Fundamental limitation of electrocatalytic methane conversion to methanol
The electrochemical oxidation of methane to methanol at remote oil fields where methane is flared is the ultimate solution to harness this valuable energy resource.</p
- âŚ