8,034 research outputs found
Electron release of rare gas atom clusters under an intense laser pulse
Calculating the energy absorption of atomic clusters as a function of the
laser pulse length we find a maximum for a critical . We show that
can be linked to an optimal cluster radius . The existence of this
radius can be attributed to the enhanced ionization mechanism originally
discovered for diatomic molecules. Our findings indicate that enhanced
ionization should be operative for a wide class of rare gas clusters. From a
simple Coulomb explosion ansatz, we derive an analytical expression relating
the maximum energy release to a suitably scaled expansion time which can be
expressed with the pulse length .Comment: 4 pages, 5 figure
Semileptonic decays in the light-cone QCD sum rules
Semileptonic () decays are investigated systematically in the
light-cone QCD sum rules. Special emphasis is put on the LCSR calculation on
weak form factors with an adequate chiral current correlator, which turns out
to be particularly effective to control the pollution by higher twist
components of spectator mesons. The result for each channel depends on the
distribution amplitude of the the producing meson. The leading twist
distribution amplitudes of the related heavy mesons and charmonium are worked
out by a model approach in the reasonable way. A practical scenario is
suggested to understand the behavior of weak form factors in the whole
kinematically accessible ranges. The decay widths and branching ratios are
estimated for several () decay modes of current interest.Comment: 8 pages, talk given by the first arthur at 4th International
Conference on Flavor Physics (ICFP 2007), Beijing, China, Sept 24-28, 200
Research on operation characteristics of wind supercharged solar chimney dust haze removal street light
To realize distributed dust haze removal in street canyons, an innovative wind supercharged solar chimney dust haze removal street light is proposed. The design couples solar chimney technology with municipal street lighting, utilizing thermal pressure, chimney effect and wind supercharged wheel to power the system, which achieves the dual function of lighting and dust haze removal. Operational testing on a small-scale model showed: the airflow warms up the most in the inlet area, and the model creates updrafts with a dust haze removal effect. The filtration system consists of various filter screens arranged by descending filtration efficiency: HEPA, primary filter cotton, activated carbon and nylon filter screens, with airflow velocity in the flow runner in the opposite order. The average filtration efficiency is positively correlated with the pressure drop and negatively correlated with the overflow airflow. A combination of different material filter screens is more effective than simply increasing the thickness of a single filter screen. A single layer of 10 mm primary filter cotton has the highest total mass flow of clean air, reaching 4.18 g. HEPA has the highest average filtration efficiency at 93.1 %. This innovative approach offers an efficient solution for urban air purification while maintaining street lighting functionality
On the monodromy of the moduli space of Calabi-Yau threefolds coming from eight planes in
It is a fundamental problem in geometry to decide which moduli spaces of
polarized algebraic varieties are embedded by their period maps as Zariski open
subsets of locally Hermitian symmetric domains. In the present work we prove
that the moduli space of Calabi-Yau threefolds coming from eight planes in
does {\em not} have this property. We show furthermore that the
monodromy group of a good family is Zariski dense in the corresponding
symplectic group. Moreover, we study a natural sublocus which we call
hyperelliptic locus, over which the variation of Hodge structures is naturally
isomorphic to wedge product of a variation of Hodge structures of weight one.
It turns out the hyperelliptic locus does not extend to a Shimura subvariety of
type III (Siegel space) within the moduli space. Besides general Hodge theory,
representation theory and computational commutative algebra, one of the proofs
depends on a new result on the tensor product decomposition of complex
polarized variations of Hodge structures.Comment: 26 page
Hyperon polarization in e^-p --> e^-HK with polarized electron beams
We apply the picture proposed in a recent Letter for transverse hyperon
polarization in unpolarized hadron-hadron collisions to the exclusive process
e^-p --> e^-HK such as e^-p-->e^-\Lambda K^+, e^-p --> e^-\Sigma^+ K^0, or
e^-p--> e^-\Sigma^0 K^+, or the similar process e^-p\to e^-n\pi^+ with
longitudinally polarized electron beams. We present the predictions for the
longitudinal polarizations of the hyperons or neutron in these reactions, which
can be used as further tests of the picture.Comment: 15 pages, 2 figures. submitted to Phys. Rev.
Spin structure and longitudinal polarization of hyperon in e+e- annihilation at high energies
Longitudinal polarizations of different kinds of hyperons produced in e+e-
annihilation at LEP I and LEP II energies in different event samples are
calculated using two different pictures for the spin structure of hyperon: that
drawn from polarized deep inelastic lepton-nucleon scattering data or that
using SU(6) symmetric wave functions. The result shows that measurements of
such polarizations should provide useful information to the question of which
picture is more suitable in describing the spin effects in the fragmentation
processes.Comment: 26 pages with 10 figures. Submitted to Phys. Rev.
Understanding and building upon pioneering work of Nobel Prize in Physics 2021 laureates Syukuro Manabe and Klaus Hasselmann: From greenhouse effect to Earth system science and beyond
The Nobel Prize in Physics 2021 was awarded jointly to Syukuro Manabe, Klaus Hasselmann, and Giorgio Parisi for their groundbreaking contributions to our understanding of complex systems. This is the first time that climate scientists were awarded the Nobel Physics Prize. Here, we present the evolution of climate science in the past similar to 200 years and highlight the landmarks of the developments in advancing our understanding of climate change, placing the pioneering contributions of Manabe and Hasselmann into a historical perspective. The backbone of modern climate science is further discussed in the context of the development of the discipline from the discovery of the greenhouse effect to the formation of Earth system science. Perspectives on the future development of climate science are also presented
Enhanced ionization in small rare gas clusters
A detailed theoretical investigation of rare gas atom clusters under intense
short laser pulses reveals that the mechanism of energy absorption is akin to
{\it enhanced ionization} first discovered for diatomic molecules. The
phenomenon is robust under changes of the atomic element (neon, argon, krypton,
xenon), the number of atoms in the cluster (16 to 30 atoms have been studied)
and the fluency of the laser pulse. In contrast to molecules it does not
dissappear for circular polarization. We develop an analytical model relating
the pulse length for maximum ionization to characteristic parameters of the
cluster
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