5,102 research outputs found
Higher-dimensional operators in SUSY SO(10) GUT models
SO(10) GUT models with only small Higgs fields use higher-dimensional
operators to generate realistic fermion mass matrices. In particular, a Higgs
field in the spinor representation, 16^d_H, acquires a weak scale vev. We
include the weak vev of the corresponding field \bar{16}^u_H and investigate
the effect on two successful models, one by Albright and Barr (AB) and another
by Babu, Pati and Wilczek (BPW). We find that the BPW model is a particular
case within a class of models with identical fermion masses and mixings. In
contrast, we expect corrections to the parameters of AB-type models.Comment: 3 page
Electrolytic silver ion cell sterilizes water supply
Electrolytic water sterilizer controls microbial contamination in manned spacecraft. Individual sterilizer cells are self-contained and require no external power or control. The sterilizer generates silver ions which do not impart an unpleasant taste to water
Net Baryon Fluctuations from a Crossover Equation of State
We have constructed an equation of state which smoothly interpolates between
an excluded volume hadron resonance gas at low energy density to a plasma of
quarks and gluons at high energy density. This crossover equation of state
agrees very well with lattice calculations at both zero and nonzero baryon
chemical potential. We use it to compute the variance, skewness, and kurtosis
of fluctuations of baryon number, and compare to measurements of proton number
fluctuations in central Au-Au collisions as measured by the STAR collaboration
in a beam energy scan at the Relativistic Heavy Ion Collider. The crossover
equation of state can reproduce the data if the fluctuations are frozen out at
temperatures well below than the average chemical freeze-out.Comment: 5 pages, 7 figures. arXiv admin note: substantial text overlap with
arXiv:1506.0340
Matching Excluded Volume Hadron Resonance Gas Models and Perturbative QCD to Lattice Calculations
We match three hadronic equations of state at low energy densities to a
perturbatively computed equation of state of quarks and gluons at high energy
densities. One of them includes all known hadrons treated as point particles,
which approximates attractive interactions among hadrons. The other two
include, in addition, repulsive interactions in the form of excluded volumes
occupied by the hadrons. A switching function is employed to make the crossover
transition from one phase to another without introducing a thermodynamic phase
transition. A chi-square fit to accurate lattice calculations with temperature
MeV determines the parameters. These parameters quantify the
behavior of the QCD running gauge coupling and the hard core radius of protons
and neutrons, which turns out to be fm. The most physically
reasonable models include the excluded volume effect. Not only do they include
the effects of attractive and repulsive interactions among hadrons, but they
also achieve better agreement with lattice QCD calculations of the equation of
state. The equations of state constructed in this paper do not result in a
phase transition, at least not for the temperatures and baryon chemical
potentials investigated. It remains to be seen how well these equations of
state will represent experimental data on high energy heavy ion collisions when
implemented in hydrodynamic simulations.Comment: 19 pages, 9 figure
Water management system and an electrolytic cell therefor Patent
Description of electrical equipment and system for purification of waste water by producing silver ions for bacterial contro
Central Policies for Local Debt: The Case of Teacher Pensions
The recent debt crises in New York City and Cleveland, the deterioration of public infra-structures in certain of our states and larger cities, and the occasional bankruptcy of smaller pension plans suggest that not all of local finance stands on a sound fiscal base. This paper examines the trends in funding for one form of state and local government debt--teacher pensions underfundings -- and asks what a central government might do to check any unwanted growth in these liabilities. The analysis concludes (i) that this form of state-local debt is sizeable and growing, (ii) that state and local governments have an implicit pay-as-you-go bias in pension financing which encourages the growth of debt, but (iii) central government benefit and funding regulations or debt relief policies can slow, or even reverse, that growth.
Lifting a Realistic SO(10) Grand Unified Model to Five Dimensions
It has been shown recently that the problem of rapid proton decay induced by
dimension five operators arising from the exchange of colored Higgsinos can be
simply avoided in grand unified models where a fifth spatial dimension is
compactified on an orbifold. Here we demonstrate that this idea can be used to
solve the Higgsino-mediated proton decay problem in any realistic SO(10) model
by lifting that model to five dimensions. A particular SO(10) model that has
been proposed to explain the pattern of quark and lepton masses and mixings is
used as an example. The idea is to break the SO(10) down to the Pati-Salam
symmetry by the orbifold boundary conditions. The entire four-dimensional
SO(10) model is placed on the physical SO(10) brane except for the gauge
fields, the 45 and a single 10 of Higgs fields, which are placed in the
five-dimensional bulk. The structure of the Higgs superpotential can be
somewhat simplified in doing so, while the Yukawa superpotential and mass
matrices derived from it remain essentially unaltered.Comment: 17 pages, version to be published in Phys. Rev. D with expanded
discussion of the suppression of dim-5 proton decay operator
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