3,498 research outputs found
Energy Spectrum and Phase Transition of Superfluid Fermi Gas of Atoms on Noncommutative Space
Based on the Bogoliubov non-ideal gas model, we discuss the energy spectrum
and phase transition of the superfluid Fermi gas of atoms with a weak
attractive interaction on the canonical noncommutative space. Because the
interaction of a BCS-type superfluid Fermi gas originates from a pair of
Fermionic quasi-particles with opposite momenta and spins, the Hamiltonian of
the Fermi gas on the noncommutative space can be described in terms of the
ordinary creation and annihilation operators related to the commutative space,
while the noncommutative effect appears only in the coefficients of the
interacting Hamiltonian. As a result, we can rigorously solve the energy
spectrum of the Fermi gas on the noncommutative space exactly following the way
adopted on the commutative space without the use of perturbation theory. In
particular, different from the previous results on the noncommutative
degenerate electron gas and superconductor where only the first order
corrections of the ground state energy level and energy gap were derived, we
obtain the nonperturbative energy spectrum for the noncommutative superfluid
Fermi gas, and find that each energy level contains a corrected factor of
cosine function of noncommutative parameters. In addition, our result shows
that the energy gap becomes narrow and the critical temperature of phase
transition from a superfluid state to an ordinary fluid state decreases when
compared with that in the commutative case
Analysis of the scalar, axialvector, vector, tensor doubly charmed tetraquark states with QCD sum rules
In this article, we construct the axialvector-diquark-axialvector-antidiquark
type currents to interpolate the scalar, axialvector, vector, tensor doubly
charmed tetraquark states, and study them with QCD sum rules systematically by
carrying out the operator product expansion up to the vacuum condensates of
dimension 10 in a consistent way, the predicted masses can be confronted to the
experimental data in the future. We can search for those doubly charmed
tetraquark states in the Okubo-Zweig-Iizuka super-allowed strong decays to the
charmed meson pairs.Comment: 23 pages, 29 figures. arXiv admin note: substantial text overlap with
arXiv:1708.0454
Revisit assignments of the new excited states with QCD sum rules
In this article, we distinguish the contributions of the positive parity and
negative parity states, study the masses and pole residues of the
1S, 1P, 2S and 2P states with the spin and
using the QCD sum rules in a consistent way, and revisit the
assignments of the new narrow excited states. The predictions
support assigning the to be the 1P state with
, assigning the to be the 1P
state with or the 2S state with
, and assigning to be the 2S
state with .Comment: 19 pages, 22 figures. arXiv admin note: text overlap with
arXiv:1705.0774
Energy-Efficient Non-Orthogonal Transmission under Reliability and Finite Blocklength Constraints
This paper investigates an energy-efficient non-orthogonal transmission
design problem for two downlink receivers that have strict reliability and
finite blocklength (latency) constraints. The Shannon capacity formula widely
used in traditional designs needs the assumption of infinite blocklength and
thus is no longer appropriate. We adopt the newly finite blocklength coding
capacity formula for explicitly specifying the trade-off between reliability
and code blocklength. However, conventional successive interference
cancellation (SIC) may become infeasible due to heterogeneous blocklengths. We
thus consider several scenarios with different channel conditions and
with/without SIC. By carefully examining the problem structure, we present in
closed-form the optimal power and code blocklength for energy-efficient
transmissions. Simulation results provide interesting insights into conditions
for which non-orthogonal transmission is more energy efficient than the
orthogonal transmission such as TDMA.Comment: accepted by IEEE GlobeCom workshop on URLLC, 201
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