SEMINAR ANNOUNCEMENT: “Thermodynamic behavior of a one-dimensional Bose gas at low temperature and superfluidity in neutron-star matter"
Giulia De Rosi INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, Italy
- https://fisica.upc.edu/es/eventos/seminar-announcement-201cthermodynamic-behavior-of-a-one-dimensional-bose-gas-at-low-temperature-and-superfluidity-in-neutron-star-matter
- SEMINAR ANNOUNCEMENT: “Thermodynamic behavior of a one-dimensional Bose gas at low temperature and superfluidity in neutron-star matter"
- 2017-07-18T11:30:00+02:00
- 2017-07-18T13:30:00+02:00
- Giulia De Rosi INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, Italy
18/07/2017 de 11:30 a 13:30 (Europe/Madrid / UTC200)
UPC campus nord, B4-212 (aula seminari)
Giulia De Rosi
INO-CNR BEC Center and Dipartimento di Fisica,
Università di Trento, Italy
“Thermodynamic behavior of a one-dimensional Bose gas at low
temperature and superfluidity in neutron-star matter"
Abstract
In the first part of the seminar, I will show that the chemical
potential of a one-dimensional (1D) interacting Bose gas exhibits a
non-monotonic temperature dependence which is peculiar of superfluids.
The effect is a direct consequence of the phononic nature of the
excitation spectrum at large wavelengths exhibited by 1D Bose gases.
For low temperatures T, I demonstrate that the coefficient in the
$T^2$ expansion of the chemical potential is defined by the
zero-temperature density dependence of the sound velocity and it has
been calculated along the crossover between the Bogoliubov
weakly-interacting gas and the Tonks-Girardeau gas of impenetrable
bosons. The theoretical predictions along the crossover are confirmed
by comparison with the exactly solvable Yang-Yang model in which the
finite-temperature equation of state is obtained numerically by
solving Bethe-ansatz equations. Finally, we have estimated finite-size
effects for a 1D ring geometry with periodic boundary conditions at
zero-temperature for various thermodynamic functions, pointing out the
occurrence of important deviations from the thermodynamic limit.
In the second part of the talk, I will show the results of a study of
the superfluid gap in pure neutron matter, associated with the
formation of Cooper pairs in the $^1S_0$ sector. The interaction
responsible of the onset of superfluidity is an effective interaction
coming from a nuclear Hamiltonian strongly constrained by
phenomenology and obtained from the correlated basis function (CBF)
perturbation theory and the formalism of cluster expansions. The
calculations have been carried out using an improved version of the
CBF effective interaction, in which three-nucleon forces are taken
into account using a microscopic model. Our results show that the
superfluid transition occurs at values of densities corresponding to
the neutron-star inner crust.
References:
[1] G. De Rosi, G. E. Astrakharchik and S. Stringari "Thermodynamic
behavior of a one-dimensional Bose gas at low temperature" Phys. Rev.
A 96, 013613 (2017)
[2] O. Benhar and G. De Rosi "Superfluid Gap in Neutron Matter from a
Microscopic Effective Interaction" arXiv: 1705.06607 (2017)
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