8,263 research outputs found
Maximal supersymmetry and exceptional groups
The article is a tribute to my old mentor, collaborator and friend Murray
Gell-Mann. In it I describe work by Pierre Ramond, Sung-Soo Kim and myself
where we describe the N = 8 Supergravity in the light-cone formalism. We show
how the Cremmer-Julia E7(7) non-linear symmetry is implemented and how the full
supermultiplet is a representation of the E7(7) symmetry. I also show how the
E7(7) symmetry is a key to understand the higher order couplings in the theory
and is very useful when we discuss possible counterterms for this theory.Comment: Proceedings of Conference in Honour of Murray Gell-Mann's 80th
Birthda
Oxidizing SuperYang-Mills from (N=4,d=4) to (N=1,d=10)
We introduce superspace generalizations of the transverse derivatives to
rewrite the four-dimensional N=4 Yang-Mills theory into the fully
ten-dimensional N=1 Yang-Mills in light-cone form. The explicit SuperPoincare
algebra is constructed and invariance of the ten-dimensional action is proved.Comment: 15 page
The BLG Theory in Light-Cone Superspace
The light-cone superspace version of the d=3, N=8 superconformal theory of
Bagger, Lambert and Gustavsson (BLG) is obtained as a solution to constraints
imposed by OSp(2,2|8) superalgebra. The Hamiltonian of the theory is shown to
be a quadratic form of the dynamical supersymmetry transformation.Comment: 45 pages, v2: reference added, minor typos corrected, published
versio
Determining the Electron-Phonon Coupling Strength in Correlated Electron Systems from Resonant Inelastic X-ray Scattering
We show that high resolution Resonant Inelastic X-ray Scattering (RIXS)
provides direct, element-specific and momentum-resolved information on the
electron-phonon (e-p) coupling strength. Our theoretical analysis demonstrates
that the e-p coupling can be extracted from RIXS spectra by determining the
differential phonon scattering cross section. An alternative, very direct
manner to extract the coupling is to use the one and two-phonon loss ratio,
which is governed by the e-p coupling strength and the core-hole life-time.
This allows measurement of the e-p coupling on an absolute energy scale.Comment: 4 pages, 3 figure
Direct Detection of Non-Chiral Dark Matter
Direct detection experiments rule out fermion dark matter that is a chiral
representation of the electroweak gauge group. Non-chiral real, complex and
singlet representations, however, provide viable fermion dark matter
candidates. Although any one of these candidates will be virtually impossible
to detect at the LHC, it is shown that they may be detected at future planned
direct detection experiments. For the real case, an irreducible radiative
coupling to quarks may allow a detection. The complex case in general has an
experimentally ruled out tree-level coupling to quarks via Z-boson exchange.
However, in the case of two SU(2)_L doublets, a higher dimensional coupling to
the Higgs can suppress this coupling, and a remaining irreducible radiative
coupling may allow a detection. Singlet dark matter could be detected through a
coupling to quarks via Higgs exchange. Since all non-chiral dark matter can
have a coupling to the Higgs, at least some of its mass can be obtained from
electroweak symmetry breaking, and this mass is a useful characterization of
its direct detection cross-section.Comment: 22 pages, 3 figures. References added. Minor corrections to match
published versio
Jet mixing under the influence of a pressure gradient
Theoretical analysis of jet mixing under influence of non-constant pressure gradien
How massless are massless fields in
Massless fields of generic Young symmetry type in space are analyzed.
It is demonstrated that in contrast to massless fields in Minkowski space whose
physical degrees of freedom transform in irreps of algebra,
massless mixed symmetry fields reduce to a number of irreps of
algebra. From the field theory perspective this means that not every massless
field in flat space admits a deformation to with the same number of
degrees of freedom, because it is impossible to keep all of the flat space
gauge symmetries unbroken in the AdS space. An equivalent statement is that,
generic irreducible AdS massless fields reduce to certain reducible sets of
massless fields in the flat limit. A conjecture on the general pattern of the
flat space limit of a general massless field is made. The example of
the three-cell ``hook'' Young diagram is discussed in detail. In particular, it
is shown that only a combination of the three-cell flat-space field with a
graviton-like field admits a smooth deformation to .Comment: 23 pages, LaTeX, a few typos correcte
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