4,213 research outputs found
Unbinned model-independent measurements with coherent admixtures of multibody neutral meson decays
Various studies of Standard Model parameters involve measuring the properties
of a coherent admixture of and states. A typical example
is the determination of the Unitarity Triangle angle in the decays
, . A model-independent approach to perform this
measurement is proposed that has superior statistical sensitivity than the
well-established method involving binning of the decay
phase space. The technique employs Fourier analysis of the complex phase
difference between and decay amplitudes and can be
easily generalised to other similar measurements, such as studies of charm
mixing or determination of the angle from decays.Comment: 24 pages, 6 figures; Updated with published versio
Thermodynamics of the Fermi gas in a nanotube
For the ideal Fermi gas that fills the space inside a cylindrical tube, there
are calculated the thermodynamic characteristics in general form for arbitrary
temperatures, namely: the thermodynamic potential, energy, entropy, equations
of state, heat capacities and compressibilities. All these quantities are
expressed through the introduced standard functions and their derivatives. The
radius of the tube is considered as an additional thermodynamic variable. It is
shown that at low temperatures in the quasi-one-dimensional case the
temperature dependencies of the entropy and heat capacities remain linear. The
dependencies of the entropy and heat capacities on the chemical potential have
sharp maximums at the points where the filling of a new discrete level begins.
The character of dependencies of thermodynamic quantities on the tube radius
proves to be qualitatively different in the cases of fixed linear and fixed
total density. At the fixed linear density these dependencies are monotonous
and at the fixed total density they have an oscillating character. Key words:
Fermi particle, nanotube, thermodynamic functions, low-dimensional systems,
equation of state, heat capacity, compressibilityComment: 12 pages, 9 figures. arXiv admin note: substantial text overlap with
arXiv:1608.0720
The equation of state and the quasiparticle mass in the degenerate Fermi system with an effective interaction
General formulas are derived for the quasiparticle effective mass and the
equation of state of the Fermi system with account of the interparticle
attraction at long distances and repulsion at short distances. Calculations are
carried out of the equation of state and the effective mass of the Fermi system
at zero temperature with the use of the modified Morse potential. It is shown
that the pair repulsive forces promote a decrease of the effective mass, and
the attractive forces promote its increase. With a certain choice of the
parameters of the potential the dependence of the pressure on the density has a
nonmonotonic character, which enables to describe the coexistence of the liquid
and gaseous phases. The influence of three-body interactions on the equation of
state and the effective mass is considered. The calculation results are
compared with experimental data concerning the quasiparticle effective mass in
the liquid He.
Key words: normal Fermi liquid, effective mass, quasiparticle, equation of
state, interaction potentialComment: 10 pages, 3 figure
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