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Heidelberg, Germany

The Max-Planck-Institut für Kernphysik is aresearch institute in Heidelberg, Germany. The institute is one of the 80 institutes of the Max-Planck-Gesellschaft , an independent, non-profit research organization. The Max Planck Institute for Nuclear Physics has been founded in 1958 under the leadership of Wolfgang Gentner. Its precursor was the Institute for Physics at the MPI for Medical Research.Today, the institute's research areas are: crossroads of particle physics and astrophysics andmany-body dynamics of atoms and molecules . There are five scientific divisions and several further research groups and junior groups. Scientific and technical departments as well as the administration support the researchers. The institute has about 390 employees, as well as many diploma students and scientific guests. The research field of Astroparticle Physics, represented by the divisions of Werner Hofmann and Manfred Lindner, combines questions related to macrocosm and microcosm. Unconventional methods of observation for gamma rays and neutrinos open new windows to the universe. What lies behind “dark matter” and “dark energy” is theoretically investigated.The research field of Quantum Dynamics is represented by the divisions of Klaus Blaum, Christoph Keitel and Joachim Ullrich. Using reaction microscopes, simple chemical reactions can be “filmed”. Storage rings and traps allow precision experiments almost under space conditions. The interaction of intense laser light with matter is investigated using quantum-theoretical methods.Further research fields are cosmic dust, atmospheric physics as well as fullerenes and other carbon molecules.Scientists at the MPIK collaborate with other research groups in Europe and all over the world and are involved in numerous international collaborations, partly in a leading role. Particularly close connections to some large-scale facilities like GSI , DESY , CERN , INFN-LNGS exist.In the local region, the Institute cooperates closely with the University of Heidelberg, where the directors and further members of the Institute are teaching. Three International Max Planck Research Schools and a graduate school serve to foster young scientists.The institute operates accelerators injecting highly charged atomic ions or molecular ions into a storage ring . The electron-beam ion trap is able to produce and store 78-fold charged mercury ions. Wikipedia.

Kopp J.,Max Planck Institute for Nuclear Physics
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

We use recently released data on the positron-to-electron ratio in cosmic rays from the AMS-02 experiment to constrain dark matter annihilation in the Milky Way. Due to the yet unexplained positron excess, limits are generally weaker than those obtained using other probes, especially gamma rays. This also means that explaining the positron excess in terms of dark matter annihilation is difficult. Only if very conservative assumptions on the dark matter distribution in the Galactic center region are adopted, it may be possible to accommodate dark matter annihilating to leptons with a cross section above 10-24 cm3/seca. We comment on several theoretical mechanisms to explain such large annihilation cross sections. © 2013 American Physical Society.

Zhang H.,Max Planck Institute for Nuclear Physics
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2012

Motivated by the recent observations on sterile neutrinos, we present a minimal extension of the canonical type-I seesaw by adding one extra singlet fermion. After the decoupling of right-handed neutrinos, an eV-scale mass eigenstate is obtained without the need of artificially inserting tiny mass scales or Yukawa couplings for sterile neutrinos. In particular, the active-sterile mixing is predicted to be of the order of 0.1. Moreover, we show a concrete flavor A 4 model, in which the required structures of the minimal extended seesaw are realized. We also comment on the feasibility of accommodating a keV sterile neutrino as an attractive candidate for warm dark matter. © 2012 Elsevier B.V.

Voitkiv A.B.,Max Planck Institute for Nuclear Physics
Physical Review Letters | Year: 2013

Transfer ionization in fast collisions between a bare ion and an atom, in which one of the atomic electrons is captured by the ion whereas another one is emitted, crucially depends on dynamic electron-electron correlations. We show that in collisions with a highly charged ion a strong field of the ion has a very profound effect on the correlated channels of transfer ionization. In particular, this field weakens (strongly suppresses) electron emission into the direction opposite (perpendicular) to the motion of the ion. Instead, electron emission is redirected into those parts of the momentum space which are very weakly populated in fast collisions with low charged ions. © 2013 American Physical Society.

Weidenmuller H.A.,Max Planck Institute for Nuclear Physics
Physical Review Letters | Year: 2011

A zeptosecond multi-MeV laser pulse may either excite a "plasma" of strongly interacting nucleons or a collective mode. We derive the conditions on laser energy and photon number such that either of these scenarios is realized. We use the nuclear giant dipole resonance as a representative example, and a random-matrix description of the fine-structure states and perturbation theory as tools. © 2011 American Physical Society.

Di Piazza A.,Max Planck Institute for Nuclear Physics
Physical Review Letters | Year: 2014

The feasibility of obtaining exact analytical results in the realm of QED in the presence of a background electromagnetic field is almost exclusively limited to a few tractable cases, where the Dirac equation in the corresponding background field can be solved analytically. This circumstance has restricted, in particular, the theoretical analysis of QED processes in intense laser fields to within the plane wave approximation even at those high intensities, achievable experimentally only by tightly focusing the laser energy in space. Here, within the Wentzel-Kramers-Brillouin approximation, we construct analytically single-particle electron states in the presence of a background electromagnetic field of general space-time structure in the realistic assumption that the initial energy of the electron is the largest dynamical energy scale in the problem. The relatively compact expression of these states opens, in particular, the possibility of investigating analytically strong-field QED processes in the presence of spatially focused laser beams, which is of particular relevance in view of the upcoming experimental campaigns in this field. © 2014 American Physical Society.

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