10,103 research outputs found
First Forcer results on deep-inelastic scattering and related quantities
We present results on the fourth-order splitting functions and coefficient
functions obtained using Forcer, a four-loop generalization of the Mincer
program for the parametric reduction of self-energy integrals. We have computed
the respective lowest three even-N and odd-N moments for the non-singlet
splitting functions and the non-singlet coefficient functions in
electromagnetic and nu+nu(bar) charged-current deep-inelastic scattering, and
the N=2 and N=4 results for the corresponding flavour-singlet quantities.
Enough moments have been obtained for an LLL-based determination of the
analytic N-dependence of the nf^3 and nf^2 parts, respectively, of the singlet
and non-singlet splitting functions. The large-N limit of the latter provides
the complete nf^2 contributions to the four-loop cusp anomalous dimension. Our
results also provide additional evidence of a non-vanishing contribution of
quartic group invariants to the cusp anomalous dimension.Comment: 11 pages, LaTeX (PoS style), 4 eps-figures. To appear in the
proceedings of `Loops & Legs 2016', Leipzig (Germany), April 201
Four-loop results on anomalous dimensions and splitting functions in QCD
We report on recent progress on the flavour non-singlet splitting functions
in perturbative QCD. The~exact four-loop (N^3LO) contribution to these
functions has been obtained in the planar limit of a large number of colours.
Phenomenologically sufficient approximate expressions have been obtained for
the parts not exactly known so far. Both cases include results for the
four-loop cusp and virtual anomalous dimensions which are relevant well beyond
the evolution of non-singlet quark distributions, for which an accuracy of
(well) below 1% has now been been reached.Comment: 11 pages, LaTeX (PoS style), 4 eps-figures. Contribution to the
proceedings of `RADCOR 2017', St. Gilgen (Austria), September 201
Generalized Jarzynski Equality under Nonequilibrium Feedback Control
The Jarzynski equality is generalized to situations in which nonequilibrium
systems are subject to a feedback control. The new terms that arise as a
consequence of the feedback describe the mutual information content obtained by
measurement and the efficacy of the feedback control. Our results lead to a
generalized fluctuation-dissipation theorem that reflects the readout
information, and can be experimentally tested using small thermodynamic
systems. We illustrate our general results by an introducing "information
ratchet," which can transport a Brownian particle in one direction and extract
a positive work from the particle
Anomalous dimensions and splitting functions beyond the next-to-next-to-leading order
We report on recent progress on the splitting functions for the evolution of
parton distributions and related quantities, the (lightlike) cusp anomalous
dimensions, in perturbative QCD. New results are presented for the four-loop
(next-to-next-to-next-to-leading order, N^3LO) contributions to the
flavour-singlet splitting functions and the gluon cusp anomalous dimension. We
present first results, the moments N=2 and N=3, for the five-loop (N^4LO)
non-singlet splitting functions.Comment: 10 pages, LaTeX (PoS style), 3 eps-figures. Contribution to the
proceedings of `Loops & Legs 2018', St. Goar (Germany), April/May 201
Antiferromagnetic Quantum Spins on the Pyrochlore Lattice
The ground state of the S=1/2 Heisenberg antiferromagnet on the pyrochlore
lattice is theoretically investigated. Starting from the limit of isolated
tetrahedra, I include interactions between the tetrahedra and obtain an
effective model for the spin-singlet ground state multiplet by third-order
perturbation. I determine its ground state using the mean-field approximation
and found a dimerized state with a four-sublattice structure, which agrees with
the proposal by Harris et al. I also discuss chirality correlations and spin
correlations for this state.Comment: 4 pages in 2-column format, 5 figures; To appear in J. Phys. Soc.
Jpn. (Mar, 2001
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