5,012 research outputs found
Can the massive neutron star PSR J0348+0432 be a hyperon star?
Whether the massive neutron star PSR J0348+0432 can change into a hyperon
star is studied in the framework of the relative mean field theory by choosing
the suitable hyperon coupling constants. We find that whether the mesons
and being considered or not, the neutron star PSR
J0348+0432 all can change into a hyperon star and the hyperon star transition
density are the same for the two cases. We also find that the canonical mass
neutron star also can change into a hyperon star in a minor hyperon star
transition density as the mesons and are not considered.
Our results confirms some of recent conclusions.Comment: 11 pages,7 figures, This paper was published in Acta Physica Polonica
B, 2017, 48(2): 171-18
The moment of inertia of the neutron star PSR J0348+0432 and its proto neutron star
The difference of the moment of inertia of the neutron star PSR J0348 + 0432
and that of its proto neutron star is studied in the framework of the
relativistic mean field theory considering baryon octet. The temperature of the
proto neutron star PSR J0348+0432 is chosen as T=5 MeV. The calculations show
that the central baryon number density of the proto neutron star PSR J0348+0432
is in the range 0.6230.813 fm, decreased by 27\% compared to
that of the neutron star PSR J0348+0432. The radius of the proto neutron star
PSR J0348+0432 is in the range 13.10112.419 km, increased by 12\%
compared to that of the neutron star PSR J0348+0432. The moment of inertia of
the proto neutron star PSR J0348+0432 is in the range
1.939101.63810 g.cm, increased by
about 27\% compared to that of the neutron star PSR J0348+0432.Comment: 5 pages,5 figures, published by Astrophys Space Sci,2017,362(5):9
The hyperons in the massive neutron star PSR J0348+0432
Whether the massive neutron star PSR J0348+0432 can become a hyperon star is
examined in the framework of the relativistic mean field theory by adjusting
the hyperon coupling constants. It is found that at the central baryon number
density of the massive neutron star PSR J0348+0432, the relative particle
number density of hyperons is smaller than those of neutrons and so it can not
change into a hyperon star. In its center, it is mainly composed of ,
and a few . We also found that for the neutron star with a
maximum mass of 1.4 M, it can change into a hyperon star and the
hyperon star transition density is 0.668 fm, at which the hyperons are
only composed of . At its center, the hyperons are also only composed
of and the ratio of the hyperons is a little larger than that of the
neutrons. This illustrates that the NS1.4M has just changed into a
hyperon star.Comment: 14 pages,8 figures, This paper was published in Chinese Journal of
Physics, 2015, 53(6): 1-1
On the moment of inertia of PSR J0348+0432
The moment of inertia of the massive neutron star PSR J0348+0432 is studied
in the framework of the relativistic mean field theory by choosing suitable
hyperon coupling constants. By this method, we find that the suggested radius
of the massive neutron star PSR J0348+0432 is in the range
km by the observation =1.972.05 M. We also find that the
suggested moment of inertia of the massive neutron star PSR J0348+0432 is
in the range =1.9073101.5940 g.cm by
the observation =1.972.05 M. Massive pulsars hint that the
interaction inside them should be very "strong". Though hyperons considered
will reduce the maximum mass, but in principle we may have models predicting
maximum masses higher than 2 M by choosing suitable parameters, in a
degree of freedom of hadron. Our calculations have proved the above and
perfectly agree with the results both of Aaron W et al and P\'etri J et al.Comment: 9 pages,3 figures, This paper was published in Chinese Journal of
Physics, 2016, 54(5): 839-84
The property difference between the neutron star PSR J0348+0432 and its proto neutron star
The property difference between the neutron star PSR J0348+0432 and its proto
neutron star is studied in the framework of the relativistic mean field theory
considering neutrino trapping. We see that the central baryon number density of
the proto neutron star PSR J0348+0432 is in the range fm, which is smaller than that of the neutron star
PSR J0348+0432 fm. Inside the neutron star
PSR J0348+0432, only the neutrons, protons, and produce,
whereas the hyperons and all do
not appear. But in the proto neutron star PSR J0348+0432, hyperons
, , and all will produce, though
their relative particle number density are still very small, no more than 2\%.
This shows that higher temperature will be advantageous to the hyperon
production
Examination of the influence of the f(975) and (1020) mesons on the surface gravitional redshift of the neutron star PSR J0348+0432
The effect of the mesons and on the surface
gravitional redshift of the neutron star PSR J0348+0432 is examined in the
framework of the relativistic mean field theory by choosing the suitable
hyperon coupling constants. We find that compared with that without considering
the mesons and , the value range of the radius of
the neutron star PSR J0348+0432 would be changed from a narrow range 12.964 km
12.364 km to a wider range 12.941 km 11.907 km corresponding to
the observation mass M=1.97 M2.05 M. We also find
that the value range of the surface gravitational redshift of the neutron
star PSR J0348+0432 changes from 0.3469 0.3997 to 0.3480 0.4263
corresponding to the observation mass M=1.97 M2.05 M
as the mesons and being considered. These mean the
radius and the surface gravitational redshift all will be constrained
in a wider scope as the mesons and being considered.
We also can see that the difference of the radius and the surface gravitational
redshift is not so large whether the mesons and being
considered or not. This indicates that the mesons and
do not play a major role in the massive neutron star PSR J0348+0432.Comment: 5 pages,3 figures, This paper was published in Physical Review C,
2015, 92(5): 05580
The properties of the neutron star PSR J0348+0432
The properties of the massive neutron star PSR J0348+0432 is calculated in
the framework of the relativistic mean field theory by choosing the suitable
hyperon coupling constants. It is found that the central energy density
and the central pressure of the massive neutron star PSR
J0348+0432 respectively are 1.5 times larger and 3.6 times larger than those of
the canonical mass neutron star. It is also found that in the neutron star PSR
J0348+0432 there are five kinds of baryons appearing: n, p, ,
and but in the canonical mass neutron star there are only
three kinds of particles appearing: n, p and . In our models, the
positive well depth will restrict the production of the
hyperons , and and therefore either in
the neutron star PSR J0348+0432 or in the canonical mass neutron star the
hyperons , and all do not appear. In
addition, our results also show that the radius of the massive neutron star
PSR J0348+0432 is less than that of the canonical mass neutron star while the
gravitational redshift of the former is larger than that of the latter.Comment: 11 pages, 7 figures, This paper was published in International
Journal of Modern Physics D, 2015, 24(8): 155005
On a Lower Bound for the Time Constant of First-Passage Percolation
We consider the Bernoulli first-passage percolation on . That is, the edge passage time is taken independently to be 1 with
probability and 0 otherwise. Let be the time constant. We
prove in this paper that for all by using Russo's
formula.Comment: 7 page
On The Waiting Time for A M/M/1 Queue with Impatience
This paper focuses on the problem of modeling the correspondence pattern for
ordinary people. Suppose that letters arrive at a rate and are
answered at a rate . Furthermore, we assume that, for a constant , a
letter is disregarded when its waiting time exceeds , and the remains are
answered in {\it last in first out} order. Let be the waiting time of the
-th {\it answered} letter. It is proved that converges weekly to
, a non-negative random variable which possesses a density with {\it
power-law} tail when and with exponential tail otherwise. Note
that this may provide a reasonable explanation to the phenomenons reported by
Oliveira and Barab\'asi in \cite{OB}.Comment: 10 page
Study of , , decays with perturbative QCD approach
We study the K, K, K
decays with perturbative QCD approach (pQCD) based on factorization. The
new orbitally excited charmonium distribution amplitudes
based on the Schr\"{o}dinger wave function of the , state for the
harmonic-oscillator potential are employed. By using the corresponding
distribution amplitudes, we calculate the branching ratio of
K, K, K decays and the
form factors and for the transition
. We obtain the branching ratio of both
K and K are at
the order of . The effects of two sets of the S-D mixing angle
and for the decay
K are studied firstly in this paper. Our
calculations show that the branching ratio of the decay
K can be raised from the order of to
the order of at the mixing angle , which can be
tested by the running LHC-b experiments.Comment: 12pages, 2 figure
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