12,886 research outputs found
Breaking the electroweak symmetry and supersymmetry by a compact extra dimension
We revisit in some more detail a recent specific proposal for the breaking of
the electroweak symmetry and of supersymmetry by a compact extra dimension.
Possible mass terms for the Higgs and the matter hypermultiplets are considered
and their effects on the spectrum analyzed. Previous conclusions are reinforced
and put on firmer ground.Comment: 25 pages, LaTeX, 9 eps figure
Oceanographic applications of the Kalman filter
The Kalman filter is a data-processing algorithm with a distinguished history in systems theory. Its application to oceanographic problems is in the embryo stage. The behavior of the filter is demonstrated in the context of an internal equatorial Rossby wave propagation problem
The Neron-Severi group of a proper seminormal complex variety
We prove a Lefschetz (1,1)-Theorem for proper seminormal varieties over the
complex numbers. The proof is a non-trivial geometric argument applied to the
isogeny class of the Lefschetz 1-motive associated to the mixed Hodge structure
on H^2.Comment: 16 pages; Mathematische Zeitschrift (2008
Role of Long-Range Correlations on the Quenching of Spectroscopic Factors
We consider the proton and neutron quasiparticle orbits around the
closed-shell 56Ni and 48Ca isotopes. It is found that large model spaces
(beyond the capability of shell-model applications) are necessary for
predicting the quenchings of spectroscopic factors.
The particle-vibration coupling is identified as the principal mechanism.
Additional correlations--due to configuration with several particle-hole
excitations--are estimated using shell-model calculations and generate an extra
reduction which is < ~4% for most quasiparticle states. The theoretical
calculations nicely agree with (e,e'p) and heavy ion knock-out experiments.
These results open a new path for a microscopic understanding of the
shell-model.Comment: Minor comments added and typos corrected. Accepted for publication on
Phys. Rev. Let
Minimal Flavour Violation with hierarchical squark masses
In a supersymmetric model with hierarchical squark masses we analyze a
pattern of flavour symmetry breaking centered on the special role of the top
Yukawa coupling and, by extension, of the full Yukawa couplings for the up-type
quarks. For sufficiently heavy squarks of the first and second generation this
leads to effective Minimal Flavour Violation of the Flavour Changing Neutral
Current amplitudes. For this to happen we determine the bounds on the masses of
the heavy squarks with QCD corrections taken into account, properly including
previously neglected effects. We believe that the view presented in this paper
altogether strengthens the case for hierarchical sfermions.Comment: 13 pages, 1 figure. v2: an equation correcte
The Hosotani Mechanism in Bulk Gauge Theories with an Orbifold Extra Space S^1/Z_2
We pursue the possibility of the scenario in which the Higgs field is
identified with the extra-space component of a bulk gauge field. The space-time
we take is M S/Z. We show that a non-trivial
Z-parity assignment allows some of the extra-space component to have
radiatively induced VEV, which strongly modifies the mass spectrum and gauge
symmetry of the theory, realized by oribifolding. In particular we investigate
the dynamical mass generation of zero-mode fermion and spontaneous gauge
symmetry breaking due to the VEV. The gauge theories we adopt are a prototype
model SU(2) and SU(3) model, of special interest as the realistic minimal
scheme to incorporate the standard model SU(2) U(1).Comment: 16 pages 3 figure
Utilization requirements. A southern California Gas Company project SAGE report: Utilization requirements
Utilization requirements are given and comparisons made of two phase III SAGE (solar assisted gas energy) installations in California: (1) a retrofit installation in an existing apartment building in El Toro, and (2) an installation in a new apartment building in Upland. Such testing in the field revealed the requirements to be met if SAGE-type installations are to become commercially practical on a widespread basis in electric and gas energy usage
Pre-MS depletion, accretion and primordial 7Li
We reconsider the role of pre-main sequence (pre-MS) Li depletion on the
basis of new observational and theoretical evidence: i) new observations of
Halpha emissions in young clusters show that mass accretion could be continuing
till the first stages of the MS, ii) theoretical implications from
helioseismology suggest large overshooting values below the bottom of the
convective envelopes. We argue here that a significant pre-MS 7Li destruction,
caused by efficient overshoot mixing, could be followed by a matter accretion
after 7Li depletion has ceased on MS thus restoring Li almost to the pristine
value. As a test case we show that a halo dwarf of 0.85 Msun with an extended
overshooting envelope starting with an initial abundance of A(Li) = 2.74 would
burn Li completely, but an accretion rate of the type 1e-8xe^{-t/3e6} Msun
yr would restore Li to end with an A(Li) = 2.31. A self-regulating
process is required to produce similar final values in a range of different
stellar masses to explain the PopII Spite plateau. However, this framework
could explain why open cluster stars have lower Li abundances than the
pre-solar nebula, the absence of Li in the most metal poor dwarfs and a number
of other features which lack of a satisfactory explanation.Comment: To be published in Memorie della Societ\`a Astronomica Italiana
Supplementi Vol. 22, Proceedings of Lithium in the cosmos, Iocco F.,
Bonifacio P., Vangioni E., ed
Less Minimal Flavour Violation
We consider the approximate U(2)^3 flavour symmetry exhibited by the quark
sector of the Standard Model and all its possible breaking terms appearing in
the quark Yukawa couplings. Taking an Effective Field Theory point of view, we
determine the current bounds on these parameters, assumed to control the
breaking of flavour in a generic extension of the Standard Model at a reference
scale Lambda. In particular, a significant bound from epsilon'/epsilon is
derived, which is relevant to Minimal Flavour Violation as well. In the
up-quark sector, the recently observed CP violation in D -> pi+ pi-, K+ K-
decays might be accounted for in this generic framework, consistently with any
other constraint.Comment: 15 pages, 1 figur
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