4,448 research outputs found
Temperature variation of the resistivity of metallic strain gauge materials Final report
Temperature effects on electrical resistivity of metallic strain gage material
Lambda-parameter of lattice QCD with Symanzik improved gluon actions
We compute the ratio Lambda_L/Lambda_MS, where the scale parameter Lambda_L
is associated with a lattice formulation of QCD. We consider a 3-parameter
family of gluon actions, which are most frequently used for O(a) improvement a`
la Symanzik. The gluon action is put togeter with standard discretizations for
fermions (Wilson/clover, overlap), to provide Lambda_L for several possible
combinations of fermion and gluon actions. We employ the background field
technique in order to calculate the 1PI 2-point function of the background
field; this leads to the coupling constant renormalization function, Z_g, at
1-loop level.
Our results are obtained for an extensive range of values for the Symanzik
coefficients.Comment: 11 pages, 3 figures, 3 table
Perturbative Renormalization Factors of Bilinear Quark Operators for Improved Gluon and Quark Actions in Lattice QCD
We calculate one-loop renormalization factors of bilinear quark operators for
gluon action including six-link loops and -improved quark action in the
limit of massless quark. We find that finite parts of one-loop coefficients of
renormalization factors diminish monotonically as either of the coefficients
or of the six-link terms are decreased below zero. Detailed
numerical results are given, for general values of the clover coefficient, for
the tree-level improved gluon action in the Symanzik approach and for the choices suggested by Wilson and by Iwasaki and from renormalization-group analyses. Compared with the case of
the standard plaquette gluon action, finite parts of one-loop coefficients are
reduced by 10--20% for the Symanzik action, and approximately by a factor two
for the renormalization-group improved gluon actions.Comment: 19 pages, REVTeX, with 3 epsf figure
ATP-dependent chromatosome remodeling
Chromatin serves to package, protect and organize the complex eukaryotic genomes to assure their stable inheritance over many cell generations. At the same time, chromatin must be dynamic to allow continued use of DNA during a cell's lifetime. One important principle that endows chromatin with flexibility involves ATP-dependent `remodeling' factors, which alter DNA-histone interactions to form, disrupt or move nucleosomes. Remodeling is well documented at the nucleosomal level, but little is known about the action of remodeling factors in a more physiological chromatin environment. Recent findings suggest that some remodeling machines can reorganize even folded chromatin fibers containing the linker histone H1, extending the potential scope of remodeling reactions to the bulk of euchromatin
Modular optical design of the LHC experimental insertions
To optimize the use of space, the LHC insertions combine dispersion matching (arc and ring separation/recombination), beam focalization at the interaction point and betatron phase advance control within a unique optical module. In this paper, we show that the significant dispersion produced by the separation/recombination dipoles can be treated separately, allowing a separation of the optical functions in the insertion. This methodology yields the flexibility and robustness needed to adapt the insertion to a lattice with a variable tune split
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