8,782 research outputs found
Persistent spin current and entanglement in the anisotropic spin ring i
We investigate the ground state persistent spin current and the pair
entanglement in one-dimensional antiferromagnetic anisotropic Heisenberg ring
with twisted boundary conditions. Solving Bethe ansatz equations numerically,
we calculate the dependence of the ground state energy on the total magnetic
flux through the ring, and the resulting persistent current. Motivated by
recent development of quantum entanglement theory, we study the properties of
the ground state concurrence under the influence of the flux through the
anisotropic Heisenberg ring. We also include an external magnetic field and
discuss the properties of the persistent current and the concurrence in the
presence of the magnetic field.Comment: 5 pages, 8 figure
Heat conduction in deformable Frenkel-Kontorova lattices: thermal conductivity and negative differential thermal resistance
Heat conduction through the Frenkel-Kontorova (FK) lattices is numerically
investigated in the presence of a deformable substrate potential. It is found
that the deformation of the substrate potential has a strong influence on heat
conduction. The thermal conductivity as a function of the shape parameter is
nonmonotonic. The deformation can enhance thermal conductivity greatly and
there exists an optimal deformable value at which thermal conductivity takes
its maximum. Remarkably, we also find that the deformation can facilitate the
appearance of the negative differential thermal resistance (NDTR).Comment: 15 pages, 7 figure
Double negative differential thermal resistance induced by the nonlinear on-site potentials
We study heat conduction through one-dimensional homogeneous lattices in the
presence of the nonlinear on-site potentials containing the bounded and
unbounded parts, and the harmonic interaction potential. We observe the
occurrence of double negative differential thermal resistance (NDTR), namely,
there exist two regions of temperature difference, where the heat flux
decreases as the applied temperature difference increases. The nonlinearity of
the bounded part contributes to NDTR at low temperatures and NDTR at high
temperatures is induced by the nonlinearity of the unbounded part. The
nonlinearity of the on-site potentials is necessary to obtain NDTR for the
harmonic interaction homogeneous lattices. However, for the anharmonic
homogeneous lattices, NDTR even occurs in the absence of the on-site
potentials, for example the rotator model.Comment: 5 pages, 4 figure
Transitions in the Standard Model Effective Field Theory
The anomalies observed in decays
have attracted much attention in recent years. In this paper, we study the
, , , , and decays, all
being mediated by the same quark-level transition, in the
Standard Model Effective Field Theory. The most relevant dimension-six
operators for these processes are , , ,
and in the Warsaw basis. Evolution of the corresponding Wilson
coefficients from the new physics scale ~TeV down to the
characteristic scale is performed at three-loop in QCD and
one-loop in EW/QED. It is found that, after taking into account the constraint
, a single
or
can still be used to resolve the
anomalies at , while a single
is already ruled out by the
measured at more than . By minimizing the
function constructed based on the current data on ,
, , , and , we obtain eleven most
trustworthy scenarios, each of which can provide a good explanation of the
anomalies at . To further discriminate these different
scenarios, we predict thirty-one observables associated with the processes
considered under each NP scenario. It is found that most of the scenarios can
be differentiated from each other by using these observables and their
correlations.Comment: 43 pages, 3 figures and 5 tables; references updated and more
discussions added, final version to be published in the journa
Revisiting the -physics anomalies in -parity violating MSSM
In recent years, several deviations from the Standard Model predictions in
semileptonic decays of -meson might suggest the existence of new physics
which would break the lepton-flavour universality. In this work, we have
explored the possibility of using muon sneutrinos and right-handed sbottoms to
solve these -physics anomalies simultaneously in -parity violating
minimal supersymmetric standard model. We find that the photonic penguin
induced by exchanging sneutrino can provide sizable lepton flavour universal
contribution due to the existence of logarithmic enhancement for the first
time. This prompts us to use the two-parameter scenario to explain anomaly. Finally, the
numerical analyses show that the muon sneutrinos and right-handed sbottoms can
explain and anomalies simultaneously,
and satisfy the constraints of other related processes, such as decays, mixing, decays, as well as
, , , , , , and decays.Comment: 10 pages, 8 figures, matches to the version published in EPJ
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