181 research outputs found
Proof of the Equivalence Theorem in the Chiral Lagrangian Formalism
A general proof of the equivalence theorem in electroweak theories with the
symmetry breaking sector described by the chiral Lagrangian is given in the
gauge by means of the Ward-Takahashi identities. The precise form of
the theorem contains a modification factor associated with each
external Goldstone boson similar to that in the standard model. is
exactly unity in our previously proposed renormalization scheme, {\it
Scheme-II}.Comment: 10 pages, A few words have been added below eq.(22) to make our
meaning more precis
The Akulov-Volkov Lagrangian, Symmetry Currents and Spontaneously Broken Extended Supersymmetry
A generalization of the Akulov-Volkov effective Lagrangian governing the self
interactions of the Nambu-Goldstone fermions associated with spontaneously
broken extended supersymmetry as well as their coupling to matter is presented
and scrutinized. The resulting currents associated with R-symmetry,
supersymmetry and space-time translations are constructed and seen to form a
supermultiplet structure.Comment: 17 pages, LaTeX; Title, abstract and introduction changes, references
adde
Anomalous Gauge Interactions of the Higgs Boson: Precision Constraints and Weak Boson Scatterings
Interaction of Higgs scalar (H) with weak gauge bosons (V=W,Z) is the {\it
key} to understand electroweak symmetry breaking (EWSB) mechanism. New physics
effects in the HVV interactions, as predicted by models of compositeness,
supersymmetry and extra dimensions, can be formulated as anomalous couplings
via a generic effective Lagrangian. We first show that the existing electroweak
precision data already impose nontrivial indirect constraints on the anomalous
HVV couplings. Then, we systematically study VV --> VV scatterings in the TeV
region, via Gold-plated pure leptonic decay modes of the weak bosons. We
demonstrate that, even for a light Higgs boson in the mass range 115GeV < m_H <
300GeV, this process can directly probe the anomalous HVV interactions at the
LHC with an integrated luminosity of 300fb^{-1}, which further supports the
``No-Lose'' theorem for the LHC to uncover the EWSB mechanism. Comparisons with
the constraints from measuring the cross section of VH associate production and
the Higgs boson decay width are also given.Comment: Version in Phys. Lett. B (v3: minor typos removed, v2,v4: fix Latex
top-margin
The Origin of Space-Time as Symmetry Breaking in String Theory
Physics in the neighbourhood of a space-time metric singularity is described
by a world-sheet topological gauge field theory which can be represented as a
twisted superconformal Wess-Zumino model with a bosonic symmetry. The measurable -hair associated with the
singularity is associated with Wilson loop integrals around gauge defects. The
breaking of
is associated with expectation values for open Wilson lines that
make the metric non-singular away from the singularity. This symmetry breaking
is accompanied by massless discrete `tachyon' states that appear as leg poles
in -matrix elements. The triviality of the -matrix in the high-energy
limit of the string model, after renormalisation by the leg pole factors,
is due to the restoration of double -symmetry at the singularity.Comment: 13 page
Equivalence Theorem and Probing the Electroweak Symmetry Breaking Sector
We examine the Lorentz non-invariance ambiguity in longitudinal weak-boson
scatterings and the precise conditions for the validity of the Equivalence
Theorem (ET). {\it Safe} Lorentz frames for applying the ET are defined, and
the intrinsic connection between the longitudinal weak-boson scatterings and
probing the symmetry breaking sector is analyzed. A universal precise
formulation of the ET is presented for both the Standard Model and the Chiral
Lagrangian formulated Electro-Weak Theories. It is shown that in electroweak
theories with strongly interacting symmetry breaking sector, the longitudinal
weak-boson scattering amplitude {\it under proper conditions} can be replaced
by the corresponding Goldstone-boson scattering amplitude in which all the
internal weak-boson lines and fermion loops are ignored.Comment: 20 pages, in LaTeX, to appear in Phys. Rev. D (1995). A few minor
corrections were made to clarify our viewpoint of the Equivalence Theorem and
compare our conclusion with those in the literatur
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
Viable Supersymmetry and Leptogenesis with Anomaly Mediation
The seesaw mechanism that explains the small neutrino masses comes naturally
with supersymmetric (SUSY) grand unification and leptogenesis. However, the
framework suffers from the SUSY flavor and CP problems, and has a severe
cosmological gravitino problem. We propose anomaly mediation as a simple
solution to all these problems, which is viable once supplemented by the
D-terms for U(1)_Y and U(1)_{B-L}. Even though the right-handed neutrino mass
explicitly breaks U(1)_{B-L} and hence reintroduces the flavor problem, we show
that it lacks the logarithmic enhancement and poses no threat to the framework.
The thermal leptogenesis is then made easily consistent with the gravitino
constraint.Comment: 5 pages, one figure, uses Revtex4; Discussion on the upper bound on
the LSP mass added. The version published in PR
S-matrices for Perturbed N=2 Superconformal Field Theory from quantum groups
S-matrices for integrable perturbations of superconformal field
theories are studied. The models we consider correspond to perturbations of the
coset theory . The perturbed models are closely
related to -affine Toda theories with a background charge tuned to .
Using the quantum group restriction of the affine Toda theories we derive the
S-matrix.Comment: 29 pages 2 figure
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