104,002 research outputs found
A model comparison of resonance lifetime modifications, a soft equation of state and non-Gaussian effects on correlations at FAIR/AGS energies
HBT correlations of pairs at FAIR/AGS energies are investigated
by using the UrQMD transport model and the CRAB analyzing program. Three
different possible sources (treatment of resonance lifetimes, a soft equation
of state and non-Gaussian effects) to understand the HBT puzzle are
investigated. Firstly, we find that different treatments of the resonance decay
time can not resolve the HBT time-related puzzle, however it can modify the HBT
radii at low transverse momenta to some extent to explain the data slightly.
Secondly, with a soft equation of state with momentum dependence, the measured
transverse momentum dependent HBT radii and ratio can be described
fairly well. Thirdly, non-Gaussian effects are visible in the calculated
correlation function. Using the Edgeworth expansion, one finds that the
non-Gaussian effect is strongest in the longitudinal direction and weakest in
the sideward direction.Comment: 18 pages, 6 figures. To be published in J.Phys.
and dibaryons in SU(3) chiral quark model
The binding energy of the six quark system with strangeness s=-3 is
investigated under the chiral SU(3) constituent quark model in the framework of
. The calculations of the single channel with spin S=2 and the
single channel with spin S=3 are performed. The results show
that both systems could be dibaryons and the interaction induced by the chiral
field plays a very important role on forming bound states in the systems
considered.
The phase shifts and scattering lengths in corresponding channels are also
given.Comment: LaTex file with 5 figure
M31* and its circumnuclear environment
We present a multiwavelength investigation of the circumnuclear environment
of M31. Based on Chandra/ACIS data, we tightly constrain the X-ray luminosity
of M31*, the central supermassive black hole of the galaxy, to be L (0.3-7
keV)<= 1.2x10^{36}erg/s, approximately 10^{-10} of the Eddington luminosity.
From the diffuse X-ray emission, we characterize the circumnuclear hot gas
with a temperature of ~0.3 keV and a density of ~0.1 cm^{-3}. In the absence of
an active SMBH and recent star formation, the most likely heating source for
the hot gas is Type Ia SNe. The presence of cooler, dusty gas residing in a
nuclear spiral has long been known in terms of optical line emission and
extinction. We further reveal the infrared emission of the nuclear spiral and
evaluate the relative importance of various possible ionizing sources. We show
evidence for interaction between the nuclear spiral and the hot gas, probably
via thermal evaporation. This mechanism lends natural understandings to 1) the
inactivity of M31*, in spite of a probably continuous supply of gas from outer
disk regions, and 2) the launch of a bulge outflow of hot gas, primarily
mass-loaded from the circumnuclear regions. One particular prediction of such a
scenario is the presence of gas with intermediate temperatures arising from the
conductive interfaces. The FUSE observations do show strong OVI1032
and 1038 absorption lines against the bulge starlight, but the effective OVI
column density (~4x10^{14} cm^{-2}), may be attributed to foreground gas
located in the bulge and/or the highly inclined disk of M31. Our study strongly
argues that stellar feedback, particularly in the form of energy release from
SNe Ia, may play an important role in regulating the evolution of SMBHs and the
interstellar medium in galactic bulges.Comment: Submitted to MNRAS, 33 pages, 9 figures. Comments welcom
Possible dibaryons in the quark cluster model
In the framework of RGM, the binding energy of one channel
() and are studied in the
chiral SU(3) quark cluster model. It is shown that the binding energies of the
systems are a few tens of MeV. The behavior of the chiral field is also
investigated by comparing the results with those in the SU(2) and the extended
SU(2) chiral quark models. It is found that the symmetry property of the
system makes the contribution of the relative kinetic energy
operator between two clusters attractive. This is very beneficial for forming
the bound dibaryon. Meanwhile the chiral-quark field coupling also plays a very
important role on binding. The S-wave phase shifts and the corresponding
scattering lengths of the systems are also given.Comment: LeTex with 2 ps figure
Study of 0- phase transition in hybrid superconductor-InSb nanowire quantum dot devices
Hybrid superconductor-semiconducting nanowire devices provide an ideal
platform to investigating novel intragap bound states, such as the Andreev
bound states (ABSs), Yu-Shiba-Rusinov (YSR) states, and the Majorana bound
states. The competition between Kondo correlations and superconductivity in
Josephson quantum dot (QD) devices results in two different ground states and
the occurrence of a 0- quantum phase transition. Here we report on
transport measurements on hybrid superconductor-InSb nanowire QD devices with
different device geometries. We demonstrate a realization of continuous
gate-tunable ABSs with both 0-type levels and -type levels. This allow us
to manipulate the transition between 0 and junction and explore charge
transport and spectrum in the vicinity of the quantum phase transition regime.
Furthermore, we find a coexistence of 0-type ABS and -type ABS in the same
charge state. By measuring temperature and magnetic field evolution of the
ABSs, the different natures of the two sets of ABSs are verified, being
consistent with the scenario of phase transition between the singlet and
doublet ground state. Our study provides insights into Andreev transport
properties of hybrid superconductor-QD devices and sheds light on the crossover
behavior of the subgap spectrum in the vicinity of 0- transition
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