1,445 research outputs found
Dark Matter and Neutrino Mass from the Smallest Non-Abelian Chiral Dark Sector
All pieces of concrete evidence for phenomena outside the standard model (SM)
- neutrino masses and dark matter - are consistent with the existence of new
degrees of freedom that interact very weakly, if at all, with those in the SM.
We propose that these new degrees of freedom organize themselves into a simple
dark sector, a chiral SU(3) x SU(2) gauge theory with the smallest nontrivial
fermion content. Similar to the SM, the dark SU(2) is spontaneously broken
while the dark SU(3) confines at low energies. At the renormalizable level, the
dark sector contains massless fermions - dark leptons - and stable massive
particles - dark protons. We find that dark protons with masses between 10-100
TeV satisfy all current cosmological and astrophysical observations concerning
dark matter even if dark protons are a symmetric thermal relic. The dark
leptons play the role of right-handed neutrinos and allow simple realizations
of the seesaw mechanism or the possibility that neutrinos are Dirac fermions.
In the latter case, neutrino masses are also parametrically different from
charged-fermion masses and the lightest neutrino is predicted to be massless.
Since the new "neutrino" and "dark matter" degrees of freedom interact with one
another, these two new-physics phenomena are intertwined. Dark leptons play a
nontrivial role in early universe cosmology while indirect searches for dark
matter involve, decisively, dark matter annihilations into dark leptons. These,
in turn, may lead to observable signatures at high-energy neutrino and
gamma-ray observatories, especially once one accounts for the potential
Sommerfeld enhancement of the annihilation cross-section, derived from the
low-energy dark-sector effective theory, a possibility we explore
quantitatively in some detail.Comment: 35 pages, 7 figures. Matches published versio
An Agent Based Model for the Simulation of Transport Demand and Land Use
Agent based modelling has emerged as a promising tool to provide planners with insights on social behaviour and
the interdependencies characterising urban system, particularly with respect to transport and infrastructure planning.
This paper presents an agent based model for the simulation of land use and transport demand of an urban area
of Sydney, Australia. Each individual in the model has a travel diary which comprises a sequence of trips the person
makes in a representative day as well as trip attributes such as travel mode, trip purpose, and departure time.
Individuals are associated with each other by their household relationship, which helps define the interdependencies
of their travel diary and constrains their mode choice. This allows the model to not only realistically reproduce how
the current population uses existing transport infrastructure but more importantly provide comprehensive insight into
future transport demands. The router of the traffic micro-simulator TRANSIMS is incorporated in the model to inform
the actual travel time of each trip and changes of traffic density on the road network. Simulation results show very
good agreement with survey data in terms of the distribution of trips done by transport modes and by trip purposes,
as well as the traffic density along the main road in the study area
Mutual information for examining correlations in DNA
This paper examines two methods for finding whether long-range correlations
exist in DNA: a fractal measure and a mutual information technique. We evaluate
the performance and implications of these methods in detail. In particular we
explore their use comparing DNA sequences from a variety of sources. Using
software for performing in silico mutations, we also consider evolutionary
events leading to long range correlations and analyse these correlations using
the techniques presented. Comparisons are made between these virtual sequences,
randomly generated sequences, and real sequences. We also explore correlations
in chromosomes from different species.Comment: 8 pages, 3 figure
Use of Stockpiled Berseem Clover as a Supplement for Grazed Corn Crop Residues
In the fall of 1994, mature Charolais cross cows in midgestation were allotted to duplicate 15 acre fields containing corn crop residues or a 2-to-1 mixture of corn crop residues and berseem clover planted in 3 strips at an allowance of 2.5 acres/cow for a 140 day wintering season. Similar cows were allotted duplicate drylots. All cows were fed hay as necessary to maintain a body condition score of 5. Cows grazing corn crop residues with or without berseem clover required 2596 pounds less hay per cow than cows maintained in a drylot. There was no difference in the amounts of hay required by cows grazing corn crop residues alone or with berseem clover. Initial organic matter yield of berseem clover was nearly that of corn crop residues and did not decrease as rapidly as corn crop residues. Berseem clover had a higher organic matter digestibility than corn crop residues at the initiation of grazing. Organic matter digestibility of berseem clover, however, decreased more rapidly than corn crop residues because of weathering during the winter
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