1,296 research outputs found
Energy levels and lifetimes of Gd IV and enhancement of the electron dipole moment
We have calculated energy levels and lifetimes of 4f7 and 4f6 5d
configurations of Gd IV using Hartree-Fock and configuration interaction
methods. This allows us to reduce significantly the uncertainty of the
theoretical determination of the electron electric dipole moment (EDM)
enhancement factor in this ion and, correspondingly, in gadolinium-containing
garnets for which such measurements were recently proposed. Our new value for
the EDM enhancement factor of Gd+3 is -2.2 +- 0.5. Calculations of energy
levels and lifetimes for Eu~III are used to control the accuracy.Comment: Submitted to Phys. Rev. A 6 pages, 0 figures, 3 table
Communication-Computation Efficient Gradient Coding
This paper develops coding techniques to reduce the running time of
distributed learning tasks. It characterizes the fundamental tradeoff to
compute gradients (and more generally vector summations) in terms of three
parameters: computation load, straggler tolerance and communication cost. It
further gives an explicit coding scheme that achieves the optimal tradeoff
based on recursive polynomial constructions, coding both across data subsets
and vector components. As a result, the proposed scheme allows to minimize the
running time for gradient computations. Implementations are made on Amazon EC2
clusters using Python with mpi4py package. Results show that the proposed
scheme maintains the same generalization error while reducing the running time
by compared to uncoded schemes and compared to prior coded
schemes focusing only on stragglers (Tandon et al., ICML 2017)
Stationary phase corrections in the process of bosonization of multi-quark interactions
The functional integration over the auxiliary bosonic variables of cubic
order related with the effective action of the Nambu -- Jona-Lasinio model with
't Hooft term has recently been obtained in the form of a loop expansion. Even
numbers of loops contribute to the action, while odd numbers of loops are
assigned to the measure. We consider the two-loop corrections and analyse their
effect on the low-lying pseudoscalar and scalar mass spectra, quark condensates
and weak decay constants. The results are compared to the leading order
calculations and other approaches.Comment: 22 pages, LaTeX, to appear in European Physics Journal
Model Building and Phenomenology of Flux-Induced Supersymmetry Breaking on D3-branes
We study supersymmetry breaking effects induced on D3-branes at singularities
by the presence of NSNS and RR 3-form fluxes. First, we discuss some local
constructions of chiral models from D3-branes at singularities, as well as
their global embedding in flux compactifications. The low energy spectrum of
these constructions contains features of the supersymmetric Standard Model. In
these models, both the soft SUSY parameters and the mu-term are generated by
turning on the 3-form NSNS and RR fluxes. We then explore some
model-independent phenomenological features as, e.g., the fine-tuning problem
of electroweak symmetry breaking in flux compactifications. We also comment on
other phenomenological features of this scenario.Comment: 41 pages, 10 figure
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