29,440 research outputs found
Calabi-Yau manifolds from pairs of non-compact Calabi-Yau manifolds
Most of Calabi-Yau manifolds that have been considered by physicists are
complete intersection Calabi-Yau manifolds of toric varieties or some quotients
of product types. Purpose of this paper is to introduce a different and rather
new kind of construction method of Calabi-Yau manifolds by pasting two
non-compact Calabi-Yau manifolds. We will also in some details explain a
curious and mysterious similarity with construction of some -manifolds
(also called Joyce manifolds), which are base spaces for M-theory.Comment: 10 pages. Accepted for publication in JHE
Entanglement and quantum phase transitions
We examine several well known quantum spin models and categorize behavior of
pairwise entanglement at quantum phase transitions. A unified picture on the
connection between the entanglement and quantum phase transition is given.Comment: 4 pages, 3 figure
Classification of All Poisson-Lie Structures on an Infinite-Dimensional Jet Group
A local classification of all Poisson-Lie structures on an
infinite-dimensional group of formal power series is given. All
Lie bialgebra structures on the Lie algebra {\Cal G}_{\infty} of
are also classified.Comment: 11 pages, AmSTeX fil
Exceptional del Pezzo hypersurfaces
We compute global log canonical thresholds of a large class of quasismooth
well-formed del Pezzo weighted hypersurfaces in
. As a corollary we obtain the existence
of orbifold K\"ahler--Einstein metrics on many of them, and classify
exceptional and weakly exceptional quasismooth well-formed del Pezzo weighted
hypersurfaces in .Comment: 149 pages, one reference adde
Variation in _PNPLA3_ is associated with outcomes in alcoholic liver disease
Two recent genome-wide association studies have described associations of SNP variants in _PNPLA3_ with nonalcoholic fatty liver and plasma liver enzyme levels in population based cohorts. We investigated the contributions of these variants to clinical outcomes in Mestizo subjects with a history of excessive alcohol consumption. We show that non-synonymous variant rs738409[G] (I148M) in _PNPLA3_ is strongly associated with alcoholic liver disease and progression to alcoholic cirrhosis (unadjusted OR = 2.25, P = 1.7x10^-10^; ancestry-adjusted OR = 1.79, P = 1.9x10^-5^)
Ehrenfest time in the weak dynamical localization
The quantum kicked rotor (QKR) is known to exhibit dynamical localization in
the space of its angular momentum. The present paper is devoted to the
systematic first--principal (without a regularizer) diagrammatic calculations
of the weak--localization corrections for QKR. Our particular emphasis is on
the Ehrenfest time regime -- the phenomena characteristic for the
classical--to--quantum crossover of classically chaotic systems.Comment: 27 pages, 9 figure
Bicovariant Calculus in Quantum Theory and a Generalization of the Gauss Law
We construct a deformation of the quantum algebra Fun(T^*G) associated with
Lie group G to the case where G is replaced by a quantum group G_q which has a
bicovariant calculus. The deformation easily allows for the inclusion of the
current algebra of left and right invariant one forms. We use it to examine a
possible generalization of the Gauss law commutation relations for gauge
theories based on G_q.Comment: 12 page
Circuit theory for decoherence in superconducting charge qubits
Based on a network graph analysis of the underlying circuit, a quantum theory
of arbitrary superconducting charge qubits is derived. Describing the
dissipative elements of the circuit with a Caldeira-Leggett model, we calculate
the decoherence and leakage rates of a charge qubit. The analysis includes
decoherence due to a dissipative circuit element such as a voltage source or
the quasiparticle resistances of the Josephson junctions in the circuit. The
theory presented here is dual to the quantum circuit theory for superconducting
flux qubits. In contrast to spin-boson models, the full Hilbert space structure
of the qubit and its coupling to the dissipative environment is taken into
account. Moreover, both self and mutual inductances of the circuit are fully
included.Comment: 8 pages, 3 figures; v2: published version; typo in Eq.(30) corrected,
minor changes, reference adde
Weak dynamical localization in periodically kicked cold atomic gases
Quantum kicked rotor was recently realized in experiments with cold atomic
gases and standing optical waves. As predicted, it exhibits dynamical
localization in the momentum space. Here we consider the weak localization
regime concentrating on the Ehrenfest time scale. The later accounts for the
spread-time of a minimal wavepacket and is proportional to the logarithm of the
Planck constant. We show that the onset of the dynamical localization is
essentially delayed by four Ehrenfest times and give quantitative predictions
suitable for an experimental verification.Comment: 4 pages, 2 figure
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