6,983 research outputs found
Reconstruction of Fundamental SUSY Parameters
We summarize methods and expected accuracies in determining the basic
low-energy SUSY parameters from experiments at future ee linear
colliders in the TeV energy range, combined with results from LHC. In a second
step we demonstrate how, based on this set of parameters, the fundamental
supersymmetric theory can be reconstructed at high scales near the grand
unification or Planck scale. These analyses have been carried out for minimal
supergravity [confronted with GMSB for comparison], and for a string effective
theory.Comment: 8 pages, latex, 7 figures, expanded version of contributions to the
proceedings of ICHEP.2002 (Amstersdam) and LCWS.2002 (Jeju Island
Propagators on the two-dimensional light-cone
Light-cone quantization procedure recently presented is applied to the
two-dimensional light-cone theories. By introducing the two distinct null
planes it is shown that the modification term in the two-dimensional massless
light-cone propagators suggested about twenty years ago vanishs.Comment: LATEX, 9page
3D-4D Interlinkage Of qqq Wave Functions Under 3D Support For Pairwise Bethe-Salpeter Kernels
Using the method of Green's functions within a Bethe-Salpeter framework
characterized by a pairwise qq interaction with a Lorentz-covariant 3D support
to its kernel, the 4D BS wave function for a system of 3 identical relativistic
spinless quarks is reconstructed from the corresponding 3D form which satisfies
a fully connected 3D BSE. This result is a 3-body generalization of a similar
2-body result found earlier under identical conditions of a 3D support to the
corresponding qq-bar BS kernel under Covariant Instaneity (CIA for short). (The
generalization from spinless to fermion quarks is straightforward).
To set the CIA with 3D BS kernel support ansatz in the context of
contemporary approaches to the qqq baryon problem, a model scalar 4D qqq BSE
with pairwise contact interactions to simulate the NJL-Faddeev equations is
worked out fully, and a comparison of both vertex functions shows that the CIA
vertex reduces exactly to the NJL form in the limit of zero spatial range. This
consistency check on the CIA vertex function is part of a fuller accounting for
its mathematical structure whose physical motivation is traceable to the role
of `spectroscopy' as an integral part of the dynamics.Comment: 20 pages, Latex, submitted via the account of K.-C. Yan
Heavy MSSM Higgs Bosons at CMS: "LHC wedge" and Higgs-Mass Precision
The search for MSSM Higgs bosons will be an important goal at the LHC. In
order to analyze the search reach of the CMS experiment for the heavy neutral
MSSM Higgs bosons, we combine the latest results for the CMS experimental
sensitivities based on full simulation studies with state-of-the-art
theoretical predictions of MSSM Higgs-boson properties. The experimental
analyses are done assuming an integrated luminosity of 30 or 60 fb^-1. The
results are interpreted as 5 \si discovery contours in MSSM M_A-tan_beta
benchmark scenarios. Special emphasis is put on the variation of the Higgs
mixing parameter mu. While the variation of mu can shift the prospective
discovery reach (and correspondingly the ``LHC wedge'' region) by about Delta
tan_beta= 10, the discovery reach is rather stable with respect to the impact
of other supersymmetric parameters. Within the discovery region we analyze the
accuracy with which the masses of the heavy neutral Higgs bosons can be
determined. An accuracy of 1-4% should be achievable, depending on M_A and
tan_beta.Comment: Talk given by G.W. at EPS07 (Manchester, July 2007) and talk given by
S.H. at SUSY07 (Karlsruhe, July 2007). 4 pages, 2 figure
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Photoluminescence, recombination induced luminescence and electroluminescence in epoxy resin
Dielectric breakdown of epoxies is preceded by light emission, or so-called electroluminescence, from the solid-state material. Very little is known about the luminescence properties of epoxies. The aim of this paper is to derive information that can be used as a basis to understand the nature of the excited states and their involvement in electrical degradation processes. Three different kinds of stimulation were used to excite the material luminescence. Photoluminescence was performed on the base resin, the hardener and the cured resin. Luminescence excited by a silent discharge has been analysed to identify which of the luminescent centres are optically active upon the recombination of electrical charges and could therefore act as charge traps. Finally, the electroluminescence spectrum has been acquired and compared with the previous ones. Although the identification of the origin of these emissions is far from being complete, it has been found that the photoluminescence from the cured resin is due to in-chain chromophores, which acts as trapping centres. The excited states involved in photoluminescence also seems to be involved in electroluminescence, but other components are detected as well, which could be due to the degradation of the resin molecule under the effect of the electric stress
Identification of extra neutral gauge bosons at the International Linear Collider
Heavy neutral gauge bosons, Z's, are predicted by many theoretical schemes of
physics beyond the Standard Model, and intensive searches for their signatures
will be performed at present and future high energy colliders. It is quite
possible that Z's are heavy enough to lie beyond the discovery reach expected
at the CERN Large Hadron Collider LHC, in which case only indirect signatures
of Z' exchanges may occur at future colliders, through deviations of the
measured cross sections from the Standard Model predictions. We here discuss in
this context the foreseeable sensitivity to Z's of fermion-pair production
cross sections at an e^+e^- linear collider, especially as regards the
potential of distinguishing different Z' models once such deviations are
observed. Specifically, we assess the discovery and identification reaches on
Z' gauge bosons pertinent to the E_6, LR, ALR and SSM classes of models, that
should be attained at the planned International Linear Collider (ILC). With the
high experimental accuracies expected at the ILC, the discovery and the
identification reaches on the Z' models under consideration could be increased
substantially. In particular, the identification among the different models
could be achieved for values of Z' masses in the discovery (but beyond the
identification) reach of the LHC. An important role in enhancing such reaches
is played by the electron (and possibly the positron) longitudinally polarized
beams. Also, although the purely leptonic processes are experimentally cleaner,
the measurements of c- and b-quark pair production cross sections are found to
carry important, and complementary, information on these searches.Comment: 21 page
Discriminating graviton exchange effects from other new physics scenarios in e^+e^- collisions
We study the possibility of uniquely identifying the effects of graviton
exchange from other new physics in high energy e^+e^- annihilation into
fermion-pairs. For this purpose, we use as basic observable a specific
asymmetry among integrated differential distributions, that seems particularly
suitable to directly test for such gravitational effects in the data analysis.Comment: 18 pages, including figures; v2: additional references and
acknowledgements. To appear in PR
Effect of Particle-Hole Asymmetry on the Mott-Hubbard Metal-Insulator Transition
The Mott-Hubbard metal-insulator transition is one of the most important
problems in correlated electron systems. In the past decade, much progress has
been made on examining a particle-hole symmetric form of the transition in the
Hubbard model with dynamical mean field theory where it was found that the
electronic self energy develops a pole at the transition. We examine the
particle-hole asymmetric metal-insulator transition in the Falicov-Kimball
model, and find that a number of features change when the noninteracting
density of states has a finite bandwidth. Since, generically particle-hole
symmetry is broken in real materials, our results have an impact on
understanding the metal-insulator transition in real materials.Comment: 5 pages, 3 figure
R-parity violation and uses of the rare decay sneutrino-->gamma+gamma in hadron and photon colliders
We consider implications of the loop process sneutrino -> gamma gamma in the
MSSM with R-parity violation for future experiments, where the sneutrino is
produced as the only supersymmetric particle. We present a scenario for the
R-parity violating couplings, where this clean decay, although rare with
Br(sneutrino -> gamma gamma) ~ 10^{-6}, may be useful for sneutrino detection
over a range of sneutrino masses at the LHC. Furthermore, the new
sneutrino-gamma-gamma effective coupling may induce detectable sneutrino
resonant production in gamma gamma collisions, over a considerably wide mass
range. We compare sneutrino -> gamma gamma, gg throughout the paper with the
analogous yet quantitatively very different, Higgs -> gamma gamma, gg decays
and comment on the loop processes sneutrino -> WW, ZZ.Comment: 19 pages using REVTEX, 3 figures embadded in the text using epsfi
Bino Dark Matter and Big Bang Nucleosynthesis in the Constrained E6SSM with Massless Inert Singlinos
We discuss a new variant of the E6 inspired supersymmetric standard model
(E6SSM) in which the two inert singlinos are exactly massless and the dark
matter candidate has a dominant bino component. A successful relic density is
achieved via a novel mechanism in which the bino scatters inelastically into
heavier inert Higgsinos during the time of thermal freeze-out. The two massless
inert singlinos contribute to the effective number of neutrino species at the
time of Big Bang Nucleosynthesis, where the precise contribution depends on the
mass of the Z' which keeps them in equilibrium. For example for mZ' > 1300 GeV
we find Neff \approx 3.2, where the smallness of the additional contribution is
due to entropy dilution. We study a few benchmark points in the constrained
E6SSM with massless inert singlinos to illustrate this new scenario.Comment: 24 pages, revised for publication in JHE
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