1,482 research outputs found
Left-Right Symmetry and Supersymmetric Unification
The existence of an SU(3) X SU(2)_L X SU(2)_R X U(1) gauge symmetry with g_L
= g_R at the TeV energy scale is shown to be consistent with supersymmetric
SO(10) grand unification at around 1O^{16} GeV if certain new particles are
assumed. The additional imposition of a discrete Z_2 symmetry leads to a
generalized definition of R parity as well as highly suppressed Majorana
neutrino masses. Another model based on SO(10) X SO(10) is also discussed.Comment: 11 pages, 2 figures not included, UCRHEP-T124, Apr 199
Possible Candidates for SUSY SO(10) Model with an Intermediate Scale
We study the possibility of an intermediate scale existing in supersymmetric
SO(10) grand unified theories: The intermediate scale is demanded to be around
10^{12} GeV so that neutrinos can obtain masses suitable for explaining the
experimental data on the deficit of solar neutrino with
Mikheev-Smirnov-Wolfenstein solution and the existence of hot dark matter. We
show that any Pati-Salam type intermediate symmetries are excluded by requiring
reasonable conditions and only is likely to be realized as an intermediate symmetry.Comment: LaTeX, 8 pages + 1 uuencoded eps figure (Error corrected
Exploring the properties of the phases of QCD matter - research opportunities and priorities for the next decade
This document provides a summary of the discussions during the recent joint
QCD Town Meeting at Temple University of the status of and future plans for the
research program of the relativistic heavy-ion community. A list of compelling
questions is formulated, and a number of recommendations outlining the greatest
research opportunities and detailing the research priorities of the heavy-ion
community, voted on and unanimously approved at the Town Meeting, are
presented. They are supported by a broad discussion of the underlying physics
and its relation to other subfields. Areas of overlapping interests with the
"QCD and Hadron Structure" ("cold QCD") subcommunity, in particular the
recommendation for the future construction of an Electron-Ion Collider, are
emphasized. The agenda of activities of the "hot QCD" subcommunity at the Town
Meeting is attached.Comment: 34 pages of text, 254 references,16 figure
Power Spectrum of the density of cold atomic gas in the Galaxy towards Cas A and Cygnus A
We have obtained the power spectral description of the density and opacity
fluctuations of the cold HI gas in the Galaxy towards Cas A, and Cygnus A. We
have employed a method of deconvolution, based on CLEAN, to estimate the true
power spectrum of optical depth of cold HI gas from the observed distribution,
taking into account the finite extent of the background source and the
incomplete sampling of optical depth over the extent of the source. We
investigate the nature of the underlying spectrum of density fluctuations in
the cold HI gas which would be consistent with that of the observed HI optical
depth fluctuations. These power spectra for the Perseus arm towards Cas A, and
for the Outer arm towards Cygnus A have a slope of 2.75 +/- 0.25 (3sigma
error). The slope in the case of the Local arm towards Cygnus A is 2.5, and is
significantly shallower in comparison. The linear scales probed here range from
0.01 to 3 pc. We discuss the implications of our results, the non-Kolmogorov
nature of the spectrum, and the observed HI opacity variations on small
transverse scales.Comment: 19 pages, 7 figures, to appear in the Astrophysical Journal of
November 1, 200
Fermion masses and mixings in gauge theories
The recent evidence for neutrino oscillations stimulate us to discuss again
the problem of fermion masses and mixings in gauge theories. In the standard
model, several forms for quark mass matrices are equivalent. They become
ansatze within most extensions of the standard model, where also relations
between quark and lepton sectors may hold. In a seesaw framework, these
relations can constrain the scale of heavy neutrino mass, which is often
related to the scale of intermediate or unification gauge symmetry. As a
consequence, two main scenarios arise. Hierarchies of masses and mixings may be
explained by broken horizontal symmetries.Comment: 25 pages, RevTex, no figures. Few misprints corrected and two
references adde
Leptogenesis with Left-Right domain walls
The presence of domain walls separating regions of unbroken and
is shown to provide necessary conditions for leptogenesis which
converts later to the observed Baryon aymmetry. The strength of lepton number
violation is related to the majorana neutrino mass and hence related to current
bounds on light neutrino masses. Thus the observed neutrino masses and the
Baryon asymmetry can be used to constrain the scale of Left-Right symmetry
breaking.Comment: References added, To appear in Praman
SU(16) grandunification: breaking scales, proton decay and neutrino magnetic moment
We give a detailed renormalization group analysis for the SU(16) grandunified
group with general breaking chains in which quarks and leptons transform
separately at intermediate energies. Our analysis includes the effects of Higgs
bosons. We show that the grandunification scale could be as low as GeV and give examples where new physics could exist at relatively low
energy ( GeV). We consider proton decay in this model and show that
it is consistent with a low grandunification scale. We also discuss the
possible generation of a neutrino magnetic moment in the range of to
with a very small mass by the breaking of the embedded
SU(2) symmetry at a low energy.Comment: (16 pages in REVTEX + 6 figures not included) OITS-49
Non SUSY Unification in Left-Right Models
We explore in a model independent way the possibility of achieving the non
supersymmetric gauge coupling unification within left-right symmetric models,
with the minimal particle content at the left-right mass scale which could be
as low as 1 TeV in a variety of models, and with a unification scale M in the
range GeV GeV.Comment: 18 pages, Latex file, uses epsf style, four figures. Submitted for
publication to Phys. Rev. D on Oct. 13, 199
Detection of HI 21cm Absorption by the Warm Neutral Medium
We have detected HI 21cm line absorption by the Warm Neutral Medium (WNM)
using the Westerbork Synthesis Radio Telescope. The absorption was detected
toward Cygnus A at LSR velocities of -40 and -70 km s^{-1}. These two velocity
ranges were previously identified as being relatively free of cold absorbing
clouds. The measured optical depth for the WNM along the line of sight to
Cygnus A is 8.9+/-1.9 x10^{-4} at -70 km s^{-1}, and 8.5+/-2.0 x10^{-4} at -40
km s^{-1}, with corresponding spin temperatures of 6000+/-1700 K and
4800+/-1600 K, respectively. The volume filling factor for the WNM appears to
be fairly high (f = 0.4)
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