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Publications récentes


Tetraquark-adequate formulation of QCD sum rules

Wolfgang Lucha, Dmitri Melikhov, Hagop Sazdjian

We study details of QCD sum rules à la Shifman-Vainshtein-Zakharov for exotic tetraquark states. We point out that duality relations for correlators involving exotic currents have fundamental differences compared with the duality relations for the correlators of bilinear quark currents : namely, the O(1) and O(αs) (αs the strong coupling constant) terms in the operator product expansion for the exotic correlators exactly cancel against the contributions of the two-meson states on the hadron (...)

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Tetraquark-adequate QCD sum rules for quark-exchange processes

Wolfgang Lucha, Dmitri Melikhov, and Hagop Sazdjian

We consider quark-hadron duality relations and QCD sum rules for correlators involving exotic tetraquark currents, here specializing to the case of quark-exchange processes. We point out the differences they exhibit with respect to the cases involving ordinary bilinear quark currents. Based on the observation that only diagrams possessing at least four-quark singularities can contribute to the formation of tetraquark states, we show that the quark-hadron duality relations and the (...)

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Design and characterization of a single photoelectron calibration system for the NectarCAM camera of the medium-sized telescopes of the Cherenkov Telescope Array

Barbara Biasuzzi, Kevin Pressard, Jonathan Biteau, Brice Geoffroy, Carlos Domingues Goncalves, Giulia Hull, Miktat Imre, Michaël Josselin, Alain Maroni, Bernard Mathon, Lucien Seminor, Tiina Suomijarvi, Thi Nguyen Trung, Laurent Vatrinet

Abstract In this work, we describe the optical properties of the single photoelectron (SPE) calibration system designed for NectarCAM, a camera proposed for the Medium Sized Telescopes (MST) of the Cherenkov Telescope Array (CTA). One of the goals of the SPE system, as integral part of the NectarCAM camera, consists in measuring with high accuracy the gain of its photo-detection chain. The SPE system is based on a white painted screen where light pulses are injected through a (...)

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Soft breathing modes in neutron-rich nuclei with the subtracted second random-phase approximation

D. Gambacurta, M. Grasso, and O. Sorlin

We analyze the isoscalar response related to breathing modes with particular attention being paid to low-lying excitations in neutron-rich nuclei. We use the subtracted second random-phase approximation (SSRPA) to describe microscopically the response. By increasing the neutron excess, we study the evolution of the response in Ca isotopes going from 40Ca to 48Ca and to 60Ca as well as in N=20 isotones going from 40Ca to 36S (...)

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Nuclear jets in heavy-ion collisions

P.Napolitani, M.Colonna

Head-on collisions between nuclei of different size at Fermi energies may give rise to extremely deformed dynamical regimes and patterns. Those latter, may suddenly turn into a stream of nuclear clusters, resembling collimated jets. This mechanism, which could be easily addressed in experiments, is simulated in the framework of stochastic one-body approaches. We employ the Boltzmann-Langevin equation to specifically address out-of-equilibrium conditions and handle dynamical fluctuations. (...)

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UMR 8608 - CNRS/IN2P3

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