31,267 research outputs found
The total flow concept for geothermal energy conversion
A geothermal development project has been initiated at the Lawrence Livermore Laboratory (LLL) to emphasize development of methods for recovery and conversion of the energy in geothermal deposits of hot brines. Temperatures of these waters vary from 150 C to more than 300 C with dissolved solids content ranging from less than 0.1% to over 25% by weight. Of particular interest are the deposits of high-temperature/high-salinity brines, as well as less saline brines, known to occur in the Salton Trough of California. Development of this resource will depend on resolution of the technical problems of brine handling, scale and precipitation control, and corrosion/erosion resistant systems for efficient conversion of thermal to electrical energy. Research experience to date has shown these problems to be severe. Hence, the LLL program emphasizes development of an entirely different approach called the Total Flow concept
Contamination cannot explain the lack of large-scale power in the cosmic microwave background radiation
Several anomalies appear to be present in the large-angle cosmic microwave
background (CMB) anisotropy maps of WMAP. One of these is a lack of large-scale
power. Because the data otherwise match standard models extremely well, it is
natural to consider perturbations of the standard model as possible
explanations. We show that, as long as the source of the perturbation is
statistically independent of the source of the primary CMB anisotropy, no such
model can explain this large-scale power deficit. On the contrary, any such
perturbation always reduces the probability of obtaining any given low value of
large-scale power. We rigorously prove this result when the lack of large-scale
power is quantified with a quadratic statistic, such as the quadrupole moment.
When a statistic based on the integrated square of the correlation function is
used instead, we present strong numerical evidence in support of the result.
The result applies to models in which the geometry of spacetime is perturbed
(e.g., an ellipsoidal Universe) as well as explanations involving local
contaminants, undiagnosed foregrounds, or systematic errors. Because the
large-scale power deficit is arguably the most significant of the observed
anomalies, explanations that worsen this discrepancy should be regarded with
great skepticism, even if they help in explaining other anomalies such as
multipole alignments.Comment: 9 pages. Submitted to Phys. Rev.
The -parity Violating Decays of Charginos and Neutralinos in the B-L MSSM
The MSSM is the MSSM with three right-handed neutrino chiral multiplets
and gauged symmetry. The symmetry is broken by the third family
right-handed sneutrino acquiring a VEV, thus spontaneously breaking -parity.
Within a natural range of soft supersymmetry breaking parameters, it is shown
that a large and uncorrelated number of initial values satisfy all present
phenomenological constraints; including the correct masses for the ,
bosons, having all sparticles exceeding their present lower bounds and
giving the experimentally measured value for the Higgs boson. For this "valid"
set of initial values, there are a number of different LSPs, each occurring a
calculable number of times. We plot this statistically and determine that among
the most prevalent LSPs are chargino and neutralino mass eigenstates. In this
paper, the -parity violating decay channels of charginos and neutralinos to
standard model particles are determined, and the interaction vertices and decay
rates computed analytically. These results are valid for any chargino and
neutralino, regardless of whether or not they are the LSP. For chargino and
neutralino LSPs, we will-- in a subsequent series of papers --present a
numerical study of their RPV decays evaluated statistically over the range of
associated valid initial points.Comment: 62 pages, 12 figures, added references in section 1, corrected some
calculation error
Massive Spin-2 Scattering and Asymptotic Superluminality
We place model-independent constraints on theories of massive spin-2
particles by considering the positivity of the phase shift in eikonal
scattering. The phase shift is an asymptotic -matrix observable, related to
the time delay/advance experienced by a particle during scattering. Demanding
the absence of a time advance leads to constraints on the cubic vertices
present in the theory. We find that, in theories with massive spin-2 particles,
requiring no time advance means that either: (i) the cubic vertices must appear
as a particular linear combination of the Einstein-Hilbert cubic vertex and an
potential term or (ii) new degrees of freedom or strong coupling
must enter at parametrically the mass of the massive spin-2 field. These
conclusions have implications for a variety of situations. Applied to theories
of large- QCD, this indicates that any spectrum with an isolated massive
spin-2 at the bottom must have these particular cubic self-couplings. Applied
to de Rham-Gabadadze-Tolley massive gravity, the constraint is in accord with
and generalizes previous results obtained from a shockwave calculation: of the
two free dimensionless parameters in the theory there is a one parameter line
consistent with a subluminal phase shift.Comment: 46 pages, 1 figure. v2: Minor corrections. v3: Minor edits;
orthogonalized \oplus tensor polarizations. Results are unaffecte
The Minimal SUSY Model: From the Unification Scale to the LHC
This paper introduces a random statistical scan over the high-energy initial
parameter space of the minimal SUSY model--denoted as the MSSM.
Each initial set of points is renormalization group evolved to the electroweak
scale--being subjected, sequentially, to the requirement of radiative and
electroweak symmetry breaking, the present experimental lower bounds on the
vector boson and sparticle masses, as well as the lightest neutral Higgs
mass of 125 GeV. The subspace of initial parameters that satisfies all
such constraints is presented, shown to be robust and to contain a wide range
of different configurations of soft supersymmetry breaking masses. The
low-energy predictions of each such "valid" point - such as the sparticle mass
spectrum and, in particular, the LSP - are computed and then statistically
analyzed over the full subspace of valid points. Finally, the amount of
fine-tuning required is quantified and compared to the MSSM computed using an
identical random scan. The MSSM is shown to generically require less
fine-tuning.Comment: 65 pages, 18 figure
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