7,909 research outputs found

    Electron release of rare gas atom clusters under an intense laser pulse

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    Calculating the energy absorption of atomic clusters as a function of the laser pulse length TT we find a maximum for a critical T∗T^*. We show that T∗T^* can be linked to an optimal cluster radius R∗R^*. 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 T∗T^*.Comment: 4 pages, 5 figure

    Semileptonic B(Bs,Bc)B(B_s, B_c) decays in the light-cone QCD sum rules

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    Semileptonic BB(Bs,BcB_s, B_c) 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 BB(BcB_c) 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

    On the monodromy of the moduli space of Calabi-Yau threefolds coming from eight planes in P3\mathbb{P}^3

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    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 P3\mathbb{P}^3 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

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    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

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    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

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    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

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    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

    Lambda polarization and single-spin left-right asymmetry in diffractive hadron-hadron collisions

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    We discuss Lambda polarization and single-spin left-right asymmetry in diffractive hadron-hadron scattering at high energies. We show that the physical picture proposed in a recent Letter is consistent with the experimental observation that Λ\Lambda polarization in the diffractive process, pp→ΛK+ppp\to \Lambda K^+p, is much higher than that in the inclusive reaction, pp→ΛXpp\to \Lambda X. We make predictions for the left-right asymmetry, A_N, and for the spin transfer, DNNΛD_{NN}^\Lambda, in the single-spin process p(↑)p→ΛK+pp(\uparrow)p\to \Lambda K^+p and suggest further experimental tests of the proposed picture.Comment: 14 pages, 3 ps-figures. Phys. Rev. D (in press
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