1,721,121 research outputs found
Pairing effects in the normal phase of a two-dimensional Fermi gas
No full textIn recent experiments [1, 2], a pairing gap was detected in a two-dimensional (2D)
Fermi gas with attractive interaction at temperatures where superfluidity does not occur.
A relevant question is whether this gap is a pseudogap phenomenon or is due to a molecular
state, which is always present in 2D. In this talk I will discuss how the boundary between
the pseudogap and molecular regimes can be set, and compare the theoretical results
obtained by using a t-matrix approach [3] with the above experimental data for a 2D
Fermi gas. I will also show that pseudogap phenomena occurring in 2D and 3D can be
related through a variable spanning the BCS-BEC crossover in a universal way.
[1] M. Feld, B. Fr ̈ohlich, E. Vogt, M. Koschorreck, and M. K ̈ohl, Nature 480, 75 (2011).
[2] P. A. Murthy, M. Neidig, R. Klemt, L. Bayha, I. Boettcher, T. Enss, M. Holten, G. Z ̈urn,
P. M. Preiss, and S. Jochim, arXiv:1705.10577 (2017).
[3] F. Marsiglio, P. Pieri, A. Perali, F. Palestini, and G. C. Strinati, Phys. Rev. B 91, 054509
(2015
Bose-Fermi mixtures with pairing
Full text linkI will review recent work by us on the properties of Bose-Fermi mixtures with a tunable pairing interaction
between bosons and fermions. A many-body diagrammatic approach, able to describe the condensed phase of
a Bose-Fermi mixture from weak to strong boson-fermion couplings, will be presented [1]. This approach will
be validated by comparing it with previous [2] and new dedicated fixed-node diffusion Monte Carlo
calculations. By using both methods, a universal behavior of the condensate fraction and bosonic momentum
distribution with respect to the boson concentration is found in an extended range of boson-fermion couplings
and concentrations. For vanishing boson density, the bosonic condensate fraction reduces to the quasiparticle
weight Z of the Fermi polaron studied in the context of polarized Fermi gases, unifying in this way two
apparently unrelated quantities. Finally, I will discuss an interesting effect occurring in the molecular limit of
the boson- fermion coupling, where the condensation is completely suppressed [3]. This phenomenon is an
indirect effect on bosons of the Pauli exclusion principle acting on fermions, and is the counterpart in BoseFermi
mixtures of the so called “Sarma phase” discussed for polarized Fermi gases.
[1] A. Guidini, G. Bertaina, D. Galli, and P. Pieri, arXiv:1412.2542.
[2] G. Bertaina, E. Fratini, S. Giorgini, and P. Pieri, Phys. Rev. Lett. 110, 115303 (2013).
[3] A. Guidini, G. Bertaina, E. Fratini, and P. Pieri, Phys. Rev. A 89, 023634 (2014)
Facies marginali nel Cretaceo Superiore delle Murge (Calcare di Altamura) dintorni di Ostuni.
No full textRudists facies in the Upper Cretaceous of the Murge (Altamura limestone) in the area di Ostuni
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Further data on the Campanian-Maastrchtian Apulian Platform paleogeography in the Ostuni area
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