Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Superfluid-normal phase transition in finite systems and its effect on
  damping of hot giant resonances   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.

26
The categories of this paper are: bayes-an
5
The categories of this paper are: gr-qc
16
The categories of this paper are: stat
8
The categories of this paper are: hep-ex
9
The categories of this paper are: nlin
32
The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th
2
The categories of this paper are: math
25
The categories of this paper are: patt-sol
29
The categories of this paper are: funct-an
3
The categories of this paper are: physics
14
The categories of this paper are: math-ph
10
The categories of this paper are: q-bio
18
The categories of this paper are: econ
31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con