12,439 research outputs found
Dark Matter in Universal Extra Dimension Models: vrs
We show that in a class of universal extra dimension models (UED), which
solves both the neutrino mass and proton decay problem, an admixture of KK
photon and KK right handed neutrinos can provide the required amount of cold
dark matter (CDM). This model has two parameters and ( is
the radius of the extra space dimensions and the extra neutral gauge boson
of the model). Using the value of the relic CDM density, combined with the
results from the cryogenic searches for CDM, we obtain upper limits on
of about 400-650 GeV and TeV, both being accessible to LHC. In
some regions of the parameter space, the dark matter-nucleon scattering cross
section can be as high as of cm, which can be probed by the next
round of dark matter search experiments.Comment: 13 pages, 2 figures; minor changes; to appear in Phys. Rev.
Recommended from our members
1012: AGREEMENT BETWEEN PERIPHERAL VENOUS, CENTRAL VENOUS, AND ARTERIAL LACTATE.
Addressing Cultural Pluralism from an Evangelical Christian Perspective
The complex issues surrounding cultural pluralism are rapidly turning the public square into a battlefield that divides our country. As Charles Haynes summarized, “At issue for this nation, as for much of the world, is the simple but profound question that runs through modern experience: How will we live with our deepest differences?” (Haynes, 1994). At a time when many citizens of our diverse nation have become disillusioned with the motto e pluribus unum, the Christian higher education community deals with issues involving race, ethnicity, and gender through a variety of responses ranging from isolationism to unqualified inclusion.
Evangelical institutions of higher learning are not new to the discussion of multiculturalism. They have rather a rich history of commitment to living out Christ’s commandment to love one’s neighbor as oneself (Mk 12:31) regarding each other through the unity of faith in Christ (Gal 3:28). This paper addresses the historical context for understanding cultural pluralism together with the scriptural and religious imperatives for engaging Christian and secular audiences on this issue. It identifies several of the issues surrounding cultural pluralism faced by evangelicals today, while also developing criteria for celebrating and confronting pluralism. Finally, it articulates strategies for pursuing common ground in the public arena and discusses implications for Christian higher education in addressing cultural pluralism within and beyond the college classroom
The double life of electrons in magnetic iron pnictides, as revealed by NMR
We present a phenomenological, two-fluid approach to understanding the
magnetic excitations in Fe pnictides, in which a paramagnetic fluid with
gapless, incoherent particle-hole excitations coexists with an
antiferromagnetic fluid with gapped, coherent spin wave excitations. We show
that this two-fluid phenomenology provides an excellent quantitative
description of NMR data for magnetic "122" pnictides, and argue that it finds a
natural justification in LSDA and spin density wave calculations. We further
use this phenomenology to estimate the maximum renormalisation of the ordered
moment that can follow from low-energy spin fluctuations in Fe pnictides. We
find that this is too small to account for the discrepancy between ab intio
calculations and neutron scattering measurements.Comment: Accepted for publication in Europhys. Lett. 6 pages, 4 figure
NOMAD: Non-locking, stOchastic Multi-machine algorithm for Asynchronous and Decentralized matrix completion
We develop an efficient parallel distributed algorithm for matrix completion,
named NOMAD (Non-locking, stOchastic Multi-machine algorithm for Asynchronous
and Decentralized matrix completion). NOMAD is a decentralized algorithm with
non-blocking communication between processors. One of the key features of NOMAD
is that the ownership of a variable is asynchronously transferred between
processors in a decentralized fashion. As a consequence it is a lock-free
parallel algorithm. In spite of being an asynchronous algorithm, the variable
updates of NOMAD are serializable, that is, there is an equivalent update
ordering in a serial implementation. NOMAD outperforms synchronous algorithms
which require explicit bulk synchronization after every iteration: our
extensive empirical evaluation shows that not only does our algorithm perform
well in distributed setting on commodity hardware, but also outperforms
state-of-the-art algorithms on a HPC cluster both in multi-core and distributed
memory settings
An upper limit for the water outgassing rate of the main-belt comet 176P/LINEAR observed with Herschel/HIFI
176P/LINEAR is a member of the new cometary class known as main-belt comets
(MBCs). It displayed cometary activity shortly during its 2005 perihelion
passage that may be driven by the sublimation of sub-surface ices. We have
therefore searched for emission of the H2O 110-101 ground state rotational line
at 557 GHz toward 176P/LINEAR with the Heterodyne Instrument for the Far
Infrared (HIFI) on board the Herschel Space Observatory on UT 8.78 August 2011,
about 40 days after its most recent perihelion passage, when the object was at
a heliocentric distance of 2.58 AU. No H2O line emission was detected in our
observations, from which we derive sensitive 3-sigma upper limits for the water
production rate and column density of < 4e25 molec/s and of < 3e10 cm^{-2},
respectively. From the peak brightness measured during the object's active
period in 2005, this upper limit is lower than predicted by the relation
between production rates and visual magnitudes observed for a sample of comets
by Jorda et al. (2008) at this heliocentric distance. Thus, 176P/LINEAR was
likely less active at the time of our observation than during its previous
perihelion passage. The retrieved upper limit is lower than most values derived
for the H2O production rate from the spectroscopic search for CN emission in
MBCs.Comment: 5 pages, 2 figures. Minor changes to match published versio
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