8,475 research outputs found
Power Corrections to the Universal Heavy WIMP-Nucleon Cross Section
WIMP-nucleon scattering is analyzed at order in Heavy WIMP Effective
Theory. The power corrections, where is the WIMP mass,
distinguish between different underlying UV models with the same universal
limit and their impact on direct detection rates can be enhanced relative to
naive expectations due to generic amplitude-level cancellations at leading
order. The necessary one- and two-loop matching calculations onto the
low-energy effective theory for WIMP interactions with Standard Model quarks
and gluons are performed for the case of an electroweak SU(2) triplet WIMP,
considering both the cases of elementary fermions and composite scalars. The
low-velocity WIMP-nucleon scattering cross section is evaluated and compared
with current experimental limits and projected future sensitivities. Our
results provide the most robust prediction for electroweak triplet Majorana
fermion dark matter direct detection rates; for this case, a cancellation
between two sources of power corrections yields a small total correction,
and a total cross section close to the universal limit for . For the SU(2) composite scalar, the corrections
introduce dependence on underlying strong dynamics. Using a leading chiral
logarithm evaluation, the total correction has a larger magnitude and
uncertainty than in the fermionic case, with a sign that further suppresses the
total cross section. These examples provide definite targets for future direct
detection experiments and motivate large scale detectors capable of probing to
the neutrino floor in the TeV mass regime.Comment: 12 pages, 4 figures; references added, XENONnT projection included,
version to appear in Physics Letters
Accuracy of Electronic Wave Functions in Quantum Monte Carlo: the Effect of High-Order Correlations
Compact and accurate wave functions can be constructed by quantum Monte Carlo
methods. Typically, these wave functions consist of a sum of a small number of
Slater determinants multiplied by a Jastrow factor. In this paper we study the
importance of including high-order, nucleus-three-electron correlations in the
Jastrow factor. An efficient algorithm based on the theory of invariants is
used to compute the high-body correlations. We observe significant improvements
in the variational Monte Carlo energy and in the fluctuations of the local
energies but not in the fixed-node diffusion Monte Carlo energies. Improvements
for the ground states of physical, fermionic atoms are found to be smaller than
those for the ground states of fictitious, bosonic atoms, indicating that
errors in the nodal surfaces of the fermionic wave functions are a limiting
factor.Comment: 9 pages, no figures, Late
Cystic mesothelioma of the testis in an adolescent patient.
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135297/1/jum2000196423.pd
Microwave Remote Sensing of Ocean Surface Wind Speed and Rain Rates over Tropical Storms
The value of using narrowly spaced frequencies within a microwave band to measure wind speeds and rain rates over tropical storms with radiometers is reviewed. The technique focuses on results obtained in the overflights of Hurricane Allen during 5 and 8 of August, 1980
The Anomalous Hall Effect in YBaCuO
The temperature dependence of the normal state Hall effect and
magnetoresistance in YBaCuO is investigated using the Nearly
Antiferromagnetic Fermi Liquid description of planar quasiparticles. We find
that highly anisotropic scattering at different regions of the Fermi surface
gives rise to the measured anomalous temperature dependence of the resistivity
and Hall coefficient while yielding the universal temperature dependence of the
Hall angle observed for both clean and dirty samples. This universality is
shown to arise from the limited momentum transfers available for the anomalous,
spin fluctuation scattering and is preserved for any system with strong
antiferromagnetic correlations.Comment: REVTeX, 10 pages + 4 figures in a single (compressed/uuencoded)
PostScript fil
Fermionic superfluidity: From high Tc superconductors to ultracold Fermi gases
We present a pairing fluctuation theory which self-consistently incorporates
finite momentum pair excitations in the context of BCS--Bose-Einstein
condensation (BEC) crossover, and we apply this theory to high
superconductors and ultracold Fermi gases. There are strong similarities
between Fermi gases in the unitary regime and high Tc superconductors. Here we
address key issues of common interest, especially the pseudogap. In the Fermi
gases we summarize recent experiments including various phase diagrams (with
and without population imbalance), as well as evidence for a pseudogap in
thermodynamic and other experiments.Comment: Expanded version, invited talk at the 5th International Conference on
Complex Matter -- Stripes 2006, 6 pages, 6 figure
Preclinical correction of human Fanconi anemia complementation group A bone marrow cells using a safety-modified lentiviral vector.
One of the major hurdles for the development of gene therapy for Fanconi anemia (FA) is the increased sensitivity of FA stem cells to free radical-induced DNA damage during ex vivo culture and manipulation. To minimize this damage, we have developed a brief transduction procedure for lentivirus vector-mediated transduction of hematopoietic progenitor cells from patients with Fanconi anemia complementation group A (FANCA). The lentiviral vector FancA-sW contains the phosphoglycerate kinase promoter, the FANCA cDNA, and a synthetic, safety-modified woodchuck post transcriptional regulatory element (sW). Bone marrow mononuclear cells or purified CD34(+) cells from patients with FANCA were transduced in an overnight culture on recombinant fibronectin peptide CH-296, in low (5%) oxygen, with the reducing agent, N-acetyl-L-cysteine (NAC), and a combination of growth factors, granulocyte colony-stimulating factor (G-CSF), Flt3 ligand, stem cell factor, and thrombopoietin. Transduced cells plated in methylcellulose in hypoxia with NAC showed increased colony formation compared with 21% oxygen without NAC (P<0.03), showed increased resistance to mitomycin C compared with green fluorescent protein (GFP) vector-transduced controls (P<0.007), and increased survival. Thus, combining short transduction and reducing oxidative stress may enhance the viability and engraftment of gene-corrected cells in patients with FANCA
Dynamical mean-field equations for strongly interacting fermionic atoms in a potential trap
We derive a set of dynamical mean-field equations for strongly interacting
fermionic atoms in a potential trap across a Feshbach resonance. Our derivation
is based on a variational ansatz, which generalizes the crossover wavefunction
to the inhomogeneous case, and the assumption that the order parameter is
slowly varying over the size of the Cooper pairs. The equations reduce to a
generalized time-dependent Gross-Pitaevskii equation on the BEC side of the
resonance. We discuss an iterative method to solve these mean-field equations,
and present the solution for a harmonic trap as an illustrating example to
self-consistently verify the approximations made in our derivation.Comment: replaced with the published versio
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