24,693 research outputs found
Strong and Electromagnetic Decays of The -wave Heavy Mesons
We calculate the , , , and coupling constants
between the heavy meson doublets and (0^-,1^-)/(0^+,1^+) within the
framework of the light-cone QCD sum rule at the leading order of heavy quark
effective theory. Most of the sum rules are stable with the variations of the
Borel parameter and the continuum threshold. Then we calculate the strong and
electromagnetic decay widths of the D-wave heavy mesons. Their
total widths are around several tens of MeV, which is helpful in the future
experimental search.Comment: 20 pages, 13 figure
The global geometrical property of jet events in high-energy nuclear collisions
We present the first theoretical study of medium modifications of the global
geometrical pattern, i.e., transverse sphericity () distribution of
jet events with parton energy loss in relativistic heavy-ion collisions. In our
investigation, POWHEG+PYTHIA is employed to make an accurate description of
transverse sphericity in the p+p baseline, which combines the next-to-leading
order (NLO) pQCD calculations with the matched parton shower (PS). The Linear
Boltzmann Transport (LBT) model of the parton energy loss is implemented to
simulate the in-medium evolution of jets. We calculate the event normalized
transverse sphericity distribution in central Pb+Pb collisions at the LHC, and
give its medium modifications. An enhancement of transverse sphericity
distribution at small region but a suppression at large
region are observed in A+A collisions as compared to their p+p references,
which indicates that in overall the geometry of jet events in Pb+Pb becomes
more pencil-like. We demonstrate that for events with 2 jets in the final-state
of heavy-ion collisions, the jet quenching makes the geometry more sphere-like
with medium-induced gluon radiation. However, for events with ~jets,
parton energy loss in the QCD medium leads to the events more pencil-like due
to jet number reduction, where less energetic jets may lose their energies and
then fall off the jet selection kinematic cut. These two effects offset each
other and in the end result in more jetty events in heavy-ion collisions
relative to that in p+p.Comment: 9 pages, 9 figure
Generalized Hofstadter model on a cubic optical lattice: From nodal bands to the three-dimensional quantum Hall effect
We propose that a tunable generalized three-dimensional Hofstadter
Hamiltonian can be realized by engineering the Raman-assisted hopping of
ultracold atoms in a cubic optical lattice. The Hamiltonian describes a
periodic lattice system under artificial magnetic fluxes in three dimensions.
For certain hopping configurations, the bulk bands can have Weyl points and
nodal loops, respectively, allowing the study of both the two nodal semimetal
states within this system. Furthermore, we illustrate that with proper rational
fluxes and hopping parameters, the system can exhibit the three-dimensional
quantum Hall effect when the Fermi level lies in the band gaps, which is
topologically characterized by one or two nonzero Chern numbers. Our proposed
optical-lattice system provides a promising platform for exploring various
exotic topological phases in three dimensions.Comment: 10 pages, 5 figure
Demonstration of Geometric Landau-Zener Interferometry in a Superconducting Qubit
Geometric quantum manipulation and Landau-Zener interferometry have been
separately explored in many quantum systems. In this Letter, we combine these
two approaches to study the dynamics of a superconducting phase qubit. We
experimentally demonstrate Landau-Zener interferometry based on the pure
geometric phases in this solid-state qubit. We observe the interference caused
by a pure geometric phase accumulated in the evolution between two consecutive
Landau-Zener transitions, while the dynamical phase is canceled out by a
spin-echo pulse. The full controllability of the qubit state as a function of
the intrinsically robust geometric phase provides a promising approach for
quantum state manipulation.Comment: 5 pages + 3 pages supplemental Materia
Nonadiabatic Geometric Quantum Computation Using A Single-loop Scenario
A single-loop scenario is proposed to realize nonadiabatic geometric quantum
computation. Conventionally, a so-called multi-loop approach is used to remove
the dynamical phase accumulated in the operation process for geometric quantum
gates. More intriguingly, we here illustrate in detail how to use a special
single-loop method to remove the dynamical phase and thus to construct a set of
universal quantum gates based on the nonadiabatic geometric phase shift. The
present scheme is applicable to NMR systems and may be feasible in other
physical systems.Comment: 4 pages, 3 figure
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