16,091 research outputs found
How Do We See the Nuclear Region (r < 0.1 pc) of Narrow-Line Seyfert 1 Galaxies?
We propose two statistical tests to investigate how we see the nuclear region
(r < 0.1 pc) of Narrow-Line Seyfert 1 galaxies (NLS1s). 1) The high-ionization
nuclear emission-line region (HINER) test: Seyfert 1 galaxies (S1s) have
systematically higher flux ratios of [Fe VII] lambda 6087 to [O III] lambda
5007 than Seyfert 2 galaxies (S2s). This is interpreted in that a significant
part of the [Fe VII] lambda 6087 emission arises from the inner walls of dusty
tori that cannot be seen in S2s (Murayama & Taniguchi 1998a,b). 2) The
mid-infrared test: S1s have systematically higher flux ratios of the L band
(3.5 micrometer) to the IRAS 25 micrometer band than S2s. This is also
interpreted in that a significant part of the L band emission arises from the
inner walls of dusty tori, because the tori are optically thick enough to
absorb the L band emission if the tori are viewed nearly edge on (Murayama et
al. 2000). Applying these tests to a sample of NLS1s, we have found that the
NLS1s possibly have nearly the same properties as S1s.Comment: Contributed talk presented at the Joint MPE,AIP,ESO workshop on
NLS1s, Bad Honnef, Dec. 1999, to appear in New Astronomy Reviews; also
available at http://wave.xray.mpe.mpg.de/conferences/nls1-worksho
Impact of Neutrino Oscillation Measurements on Theory
Neutrino oscillation data had been a big surprise to theorists, and indeed
they have ongoing impact on theory. I review what the impact has been, and what
measurements will have critical impact on theory in the future.Comment: 8 pages, uses aipproc, 6 figures. Plenary talk presented at Nufact
03, 5th International Workshop on Neutrino Factories & Superbeams, Columbia
University, New York, 5-11 June 200
Supersymmetry
I review phenomenologically interesting aspects of supersymmetry. First I
point out that the discovery of the positron can be regarded as a historic
analogue to the would-be discovery of supersymmetry. Second I review the recent
topics on the unification of the gauge coupling constants, --
relation, proton decay, and baryogenesis. I also briefly discuss the recent
proposals to solve the problem of flavor changing neutral currents. Finally I
argue that the measurements of supersymmetry parameters may probe the physics
at the Planck scale.Comment: LBL-36175, LaTeX, 27 pages. Psfig1.9 required. Invited talk presented
at the 22nd INS International Symposium on Physics with High Energy
Colliders, Tokyo, Japan, March 8--10, 1994, to appear in Proceedings of INS
Symposium. The original version submitted in June, only references and
spellings corrected. Five EPS figures appended in uuencoded forma
Physics Prospects --Why Do We Want a Linear Collider?--
The need to understand physics of electroweak symmetry breaking is reviewed.
An electron positron linear collider will play crucial roles in that respect.
It is discussed how the LHC and a linear collider need each other to understand
symmetry breaking mechanism unambiguously. Two popular scenarios, supersymmetry
and technicolor-like models, are used to demonstrate this point.Comment: 24 pages, 10 embedded Postscript figures, uses psfig.sty and
sprocl.sty (World Scientific). Invited talk given at 3rd International
Workshop on Physics and Experiments with e+ e- Linear Colliders, Sep 8-12,
1995, Iwate, Japan. Slightly improved from the original manuscript for the
proceeding
Nucleon Decay in GUT and Non-GUT SUSY Models
I first emphasize the importance of searching for nucleon decay in the
context of supersymmetric models. The status of minimal SUSY SU(5) model is
reviewed, which can be definitively ruled out by a combination of
superKamiokande and LEP-2 experiments. Non-minimal models may provide some
suppression in the nucleon decay rates, but there is still a good chance for
superKamiokande. I point out that the operators suppressed even by the
Planck-scale are too large. We need a suppression mechanism for the operators
at the level of , and the mechanism, I argue, may well be a flavor
symmetry. A particular example predicts to be the
dominant mode which does not arise in GUT models.Comment: 6 pages, LaTeX, Psfig, talk presented at the International Conference
on High Energy Physics, Warsaw, July 26-30, 199
Technicolorful Supersymmetry
Technicolor achieves electroweak symmetry breaking (EWSB) in an elegant and
natural way, while it suffers from severe model building difficulties. I
propose to abandon its secondary goal to eliminate scalar bosons in exchange of
solving numerous problems using supersymmetry. It helps to understand walking
dynamics much better with certain exact results. In the particular model
presented here, there is no light elementary Higgs boson and the EWSB is fully
dynamical, hence explaining the hierarchy; There is no alignment problem and no
light pseudo-Nambu-Goldstone bosons exist; The fermion masses are generated by
a ultraviolet-complete renormalizable extended technicolor sector with
techni-GIM mechanism and hence the sector is safe from
flavor-changing-neutral-current constraints; The "e+ e-'' production of
techni-states in the superconformal window is calculable; The electroweak
precision observables are (un)fortunately not calculable.Comment: 6 pages. Markus Luty pointed out a mistake in the naive dimensional
analysis in the first version of the paper. See hep-ph/0006224 for more
details. The new version uses superconformal dynamics to enhance the ETC
operato
Theory of Neutrino Masses and Mixings
Neutrino physics is going through a revolutionary progress. In this talk I
review what we have learned and why neutrino mass is so important. Neutrino
masses and mixings are already shedding new insight into the origin of flavor.
Given the evidences for neutrino mass, leptogenesis is gaining momentum as the
origin of cosmic baryon asymmetry. Best of all, we will learn a lot more in the
coming years.Comment: Talk at Lepton Photon 2001. 18 pages, LaTeX2e, uses ws-p10x7.cl
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