130,664 research outputs found
What are the Newest Developments in Change Management Models to Increase Organizational Effectiveness, Agility and Change Readiness?
Businesses are constantly required to adapt to a changing environment in order to maintain their position in the market and even more so if they are to truly grow. Few organizational change efforts tend to be complete failures, but few tend to be entirely successful either. Considerable research efforts have been deployed to fill that knowledge gap and support executives in the field of change management
Approximating Cumulative Pebbling Cost Is Unique Games Hard
The cumulative pebbling complexity of a directed acyclic graph is defined
as , where the minimum is taken over all
legal (parallel) black pebblings of and denotes the number of
pebbles on the graph during round . Intuitively, captures
the amortized Space-Time complexity of pebbling copies of in parallel.
The cumulative pebbling complexity of a graph is of particular interest in
the field of cryptography as is tightly related to the
amortized Area-Time complexity of the Data-Independent Memory-Hard Function
(iMHF) [AS15] defined using a constant indegree directed acyclic
graph (DAG) and a random oracle . A secure iMHF should have
amortized Space-Time complexity as high as possible, e.g., to deter brute-force
password attacker who wants to find such that . Thus, to
analyze the (in)security of a candidate iMHF , it is crucial to
estimate the value but currently, upper and lower bounds for
leading iMHF candidates differ by several orders of magnitude. Blocki and Zhou
recently showed that it is -Hard to compute , but
their techniques do not even rule out an efficient
-approximation algorithm for any constant . We
show that for any constant , it is Unique Games hard to approximate
to within a factor of .
(See the paper for the full abstract.)Comment: 28 pages, updated figures and corrected typo
Algebraic Bethe ansatz for integrable Kondo impurities in the one-dimensional supersymmetric t-J model
An integrable Kondo problem in the one-dimensional supersymmetric t-J model
is studied by means of the boundary supersymmetric quantum inverse scattering
method. The boundary matrices depending on the local moments of the
impurities are presented as a nontrivial realization of the graded reflection
equation algebras in a two-dimensional impurity Hilbert space. Further,the
model is solved by using the algebraic Bethe ansatz method and the Bethe ansatz
equations are obtained.Comment: 6 pages, RevTe
Spin-3/2 baryons from an anisotropic lattice QCD action
The mass spectrum of baryons in the spin-3/2 sector is computed in quenched
lattice QCD using a tadpole-improved anisotropic action. Both isospin 1/2 and
3/2 (the traditional decuplet) are considered, as well as members that contain
strange quarks. States with positive and negative parities are isolated by
parity projection, while states with spin-3/2 and spin-1/2 are separated by
spin projection. The extent to which spin projection is needed is examined. The
issue of optimal interpolating field is also investigated. The results are
discussed in relation to previous calculations and experiment.Comment: modified version to appear in Phys Rev
Spinon Phonon Interaction and Ultrasonic Attenuation in Quantum Spin Liquids
Several experimental candidates for quantum spin liquids have been discovered
in the past few years which appear to support gapless fermionic excitations called spinons. The spinons may form a Fermi sea coupled to a
gauge field, and may undergo a pairing instability. We show that despite
being charge neutral, the spinons couple to phonons in exactly the same way
that electrons do in the long wavelength limit. Therefore we can use sound
attenuation to measure the spinon mass and lifetime. Furthermore, transverse
ultrasonic attenuation is a direct probe of the onset of pairing because the
Meissner effect of the gauge field causes a "rapid fall" of the attenuation at
in addition to the reduction due to the opening of the energy gap. This
phenomenon, well known in clean superconductors, may reveal the existence of
the U(1) gauge field.Comment: 4+epsilon pages of main text + 12 pages of supplementary materia
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