dorsal/arxiv
View SchemaSuperfluid-normal phase transition in finite systems and its effect on damping of hot giant resonances
| Authors | Nguyen Dinh Dang |
|---|---|
| Categories | |
| ArXiv ID | nucl-th/0610047 |
| URL | https://arxiv.org/abs/nucl-th/0610047 |
| DOI | 10.1142/9789812770417_0015 |
Abstract
Thermal fluctuations of quasiparticle number are included making use of the secondary Bogolyubov's transformation, which turns quasiparticles operators into modified-quasiparticle ones. This restores the unitarity relation for the generalized single-particle density operator, which is violated within the Hartree-Fock-Bogolyubov (HFB) theory at finite temperature. The resulting theory is called the modified HFB (MHFB) theory, whose limit of a constant pairing interaction yields the modified BCS (MBCS) theory. Within the MBCS theory, the pairing gap never collapses at finite temperature T as it does within the BCS theory, but decreases monotonously with increasing T. It is demonstrated that this non-vanishing thermal pairing is the reason why the width of the giant dipole resonance (GDR) does not increase with T up to T around 1 MeV. At higher T, when the thermal pairing is small, the GDR width starts to increase with T. The calculations within the phonon-damping model yield the results in good agreement with the most recent experimental systematic for the GDR width as a function of T. A similar effect, which causes a small GDR width at low T, is also seen after thermal pairing is included in the thermal fluctuation model.
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"abstract": "Thermal fluctuations of quasiparticle number are included making use of the\nsecondary Bogolyubov\u0027s transformation, which turns quasiparticles operators\ninto modified-quasiparticle ones. This restores the unitarity relation for the\ngeneralized single-particle density operator, which is violated within the\nHartree-Fock-Bogolyubov (HFB) theory at finite temperature. The resulting\ntheory is called the modified HFB (MHFB) theory, whose limit of a constant\npairing interaction yields the modified BCS (MBCS) theory. Within the MBCS\ntheory, the pairing gap never collapses at finite temperature T as it does\nwithin the BCS theory, but decreases monotonously with increasing T. It is\ndemonstrated that this non-vanishing thermal pairing is the reason why the\nwidth of the giant dipole resonance (GDR) does not increase with T up to T\naround 1 MeV. At higher T, when the thermal pairing is small, the GDR width\nstarts to increase with T. The calculations within the phonon-damping model\nyield the results in good agreement with the most recent experimental\nsystematic for the GDR width as a function of T. A similar effect, which causes\na small GDR width at low T, is also seen after thermal pairing is included in\nthe thermal fluctuation model.",
"arxiv_id": "nucl-th/0610047",
"authors": [
"Nguyen Dinh Dang"
],
"categories": [
"nucl-th"
],
"doi": "10.1142/9789812770417_0015",
"title": "Superfluid-normal phase transition in finite systems and its effect on damping of hot giant resonances",
"url": "https://arxiv.org/abs/nucl-th/0610047"
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