Field theoretical description of exchange terms in nuclear systems

Serra, Milena; Otsuka, Takaharu; Akaishi, Yoshinori; Ring, P.; Hirose, Shunsuke

doi:10.1016/s0375-9474(03)01416-7

Cited by 4 publications

(8 citation statements)

References 6 publications

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“…This problem can be avoided using the RHB model [20,21], which includes an explicit pairing channel. The most successful of RMF models use the non-relativistic Gogny interaction in the pairing channel, as has been shown that there is practically no mixing between small and large components of the Dirac spinors [141,142,104]. Since this force has a finite range, it provides a natural cutoff, avoiding one of the most important problems that plague BCS and other schemes involving artificial pairing windows.…”

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confidence: 99%

Relativistic quasiparticle random phase approximation in deformed nuclei

Arteaga

Ring

2007

Progress in Particle and Nuclear Physics

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Covariant density functional theory is used to analyse the response to the E1 and M1 electromagnetic transition operators in superfluid deformed nuclei in the framework of self-consistent Hartree-Bogoliubov theory and relativistic quasiparticle random phase (RQRPA) approximation. The fully self-consistent RHB+RQRPA equations are posed for the case of axial symmetry and for three different kinds of energy functionals, and solved with the help of a new parallel code. Special care is taken in order to validate the proper decoupling of spurious modes. Results of the first multipole magnetic operator (M1) response in light and heavy deformed nuclei are presented and analysed; in particular, the scissors mode and spin excitations. Qualitative agreement with experiment is obtained for the position of the scissors mode, and its structure as a rotation of the deformed neutron density against the deformed proton density reproduced. In addition to the scissors mode, a soft M1 mode with strong orbital character is found in heavy nuclei at relatively low energies. From the analysis of the proton and neutron transition densities in the intrinsic frame, and from the structure of the RQRPA amplitudes, it is concluded that this mode corresponds to a collective rotation of the deformed neutron skin against the deformed proton-neutron core. The response in light and heavy nuclei to the electric dipole operator (E1) is also given consideration. The position of the Giant Dipole Resonance is well reproduced within the RHB+RQRPA framework in axial symmetry. The effects of superfluidity and deformation on the Pygmy Dipole Resonance are closely examined. Excellent agreement with recent experimental results is found. v vi AcknowledgementsFirst and foremost I would like to thank my supervisor, Prof. Dr. Peter Ring, not only for stimulating discussions and timely advice, but also for his support throughout the various phases of the work presented in this document. His understanding and experience in many areas has made a pleasure working with him. I am particularly grateful for his optimism and overall confidence in the project, always trying to point me on the right direction but giving me enough leeway to learn from my own mistakes.Many thanks go to Roger Hilton, who was always a source of good humour and interesting conversations while at the TUM. He patiently read the first drafts and helped me polish all the rough edges, both in the contents and in the use of the English language.It is a pleasure for me to thank all my colleagues at the TUM Theory Department and at the TUM campus in Garching, who have provided support and company during my time in Munich, with a special mention to

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confidence: 99%

Relativistic quasiparticle random phase approximation in deformed nuclei

Arteaga

Ring

2007

Progress in Particle and Nuclear Physics

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“…6 but for 44 Ca and 46 Ca. 68 Ni. First we performed the calculation with both the static phenomenological and the PVC kernels, where the strength parameter in front of the static kernel is tuned in a way that the resulting averaged pairing gaps reproduce the empirical value extracted from Ref.…”

Section: Calculations: Details Results and Discussionmentioning

confidence: 99%

Many-body correlations in nuclear superfluidity

Litvinova,

Schuck

2019

Preprint

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The two-fermion two-point correlation function in the pairing channel is discussed in the equation of motion framework. Starting from the bare two-fermion interaction, we derive the equation of motion for the two-fermion pair propagator in a strongly-correlated medium. The resulting equation is of the Dyson type with the kernel having a static and a one frequency dependent components and, thus, can be regarded as Dyson Bethe-Salpeter equation (Dyson-BSE). The many-body hierarchy generated by the dynamical interaction kernel is truncated on the level of two-body correlation functions, thus neglecting the explicit three-body and higher-rank correlations. The truncation is performed via a cluster expansion of the intermediate three-particle-one-hole correlation function irreducible in the particle-particle channel, that leads to the coupling between single fermions and emergent collective modes of excitation. The latter couplings are, thus, derived in terms of the exact mapping of the in-medium two-fermion correlation functions onto the domain of bosonic quasibound states (phonons) without introducing new parameters. The approach is applied to calculations of the pairing gaps in medium-mass nuclear systems, that include calcium, nickel and tin isotopic chains.

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“…Thus, the pairing matrix elements are superpositions of the direct matrix elements with multipolarities allowed by the values of angular momenta of the proton-neutron pair configurations [53].…”

Section: Formalismmentioning

confidence: 99%

Soft modes in the proton–neutron pairing channel as precursors of deuteron condensate in N=Z nuclei

2018

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Relativistic nuclear response theory is formulated for the proton-neutron pairing, or deuteron transfer, channel. The approach is based on the meson-nucleon Lagrangian of Quantum Hadrodynamics (QHD) and advances the relativistic field theory to connect consistently the high-energy scale of heavy mesons, the medium-energy range of the pion and the low-energy domain of emergent collective vibrations (phonons) in a parameter-free way. Mesons and phonons build up the in-medium nucleon-nucleon interaction in spin-isospin transfer channels, in particular, the phonon-exchange part takes care of the leading-order retardation effects. In this framework, we explore J π = 0 + and J π = 1 + channels of the nuclear response to the proton-neutron pair removal and addition in 56 Ni and 100 Sn with a special focus on the lowest (soft) modes as precursors of deuteron condensate and candidates for being the mediators of the proton-neutron pairing interaction.

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Field theoretical description of exchange terms in nuclear systems

Cited by 4 publications

References 6 publications

Relativistic quasiparticle random phase approximation in deformed nuclei

Relativistic quasiparticle random phase approximation in deformed nuclei

Many-body correlations in nuclear superfluidity

Soft modes in the proton–neutron pairing channel as precursors of deuteron condensate in N=Z nuclei

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