2,682 research outputs found
Quantization of Black Holes
We show that black holes can be quantized in an intuitive and elegant way
with results in agreement with conventional knowledge of black holes by using
Bohr's idea of quantizing the motion of an electron inside the atom in quantum
mechanics. We find that properties of black holes can be also derived from an
Ansatz of quantized entropy \Delta S=4\pi k {\Delta R / \lambdabar}, which
was suggested in a previous work to unify the black hole entropy formula and
Verlinde's conjecture to explain gravity as an entropic force. Such an Ansatz
also explains gravity as an entropic force from quantum effect. This suggests a
way to unify gravity with quantum theory. Several interesting and surprising
results of black holes are given from which we predict the existence of
primordial black holes ranging from Planck scale both in size and energy to big
ones in size but with low energy behaviors.Comment: Latex 7 pages, no figure
Isospin violation in via hadronic loops
In this work, we study the isospin-violating decay of
and quantify the electromagnetic (EM) transitions and intermediate meson
exchanges as two major sources of the decay mechanisms. In the EM decays, the
present datum status allows a good constraint on the EM decay form factor in
the vector meson dominance (VMD) model, and it turns out that the EM transition
can only account for about of the branching ratio for . The intermediate meson exchanges, (intermediate
interaction via exchanges), (intermediate
rescattering via kaon exchanges), and
(intermediate rescattering via exchanges), which evade the
naive Okubo-Zweig-Iizuka (OZI) rule, serve as another important contribution to
the isospin violations. They are evaluated with effective Lagrangians where
explicit constraints from experiment can be applied. Combining these three
contributions, we obtain results in good agreement with the experimental data.
This approach is also extended to , where
we find contributions from the , and
loops are negligibly small, and the isospin violation is
likely to be dominated by the EM transition.Comment: Revised version resubmitted to PRD; Additional loop contributions
included; Conclusion unchange
Magneto-optical properties of semiconductor nanocrystals in glass
Understanding of the spin and exciton properties in colloidal nanostructures paves the way for their applications in a variety of fields, such as spintronics and quantum science and technology. Using magneto-optical experimental techniques, the fundamental properties such as polarization, g-factor, spin dynamics in three kind of semiconductor nanocrystals (NCs), i.e. CdSe, CuCl and all-inorganic perovskite (CsPbBr3, CsPbI3) are studied, which help to understand the exciton fine structures and related interac- tions in each material.
By combining both the experimental and theoretical efforts, the puzzling behavior of the polarized emission of dark excitons in the ensemble of CdSe NCs is explained by considering the nanocrystal size dispersion and phonon effect. The spin coherent dynamics in the pump-probe measurements show two components, i.e. one oscillating and one nonoscillating. The Larmor frequency from the oscillating component is unambiguously assigned to the electron based on the theoretical analysis. While the nonoscillating component is clarified to be contributed by the frozen exciton spin polarization created by the pump pulse in NCs with heavy-light hole splitting determined by the crystal field.
The polarization properties and g-factors in CuCl NCs are investigated comprehensively, where the degree of circular polarization of the Z3 exciton emission is found to increase linearly with the magnetic field at low temperatures up to 8 T. In the spin-flip Raman scattering measurements, a g-factor about 2 is resolved which can be assigned to the electron.
The magnetic field and temperature dependent recombination dynamics reveal a dark ground state in both CsPbBr3 and CsPbI3 NCs with corresponding bright-dark exciton splitting being 4.2 meV and 6.5 meV, respectively. In CsPbI3 NCs, very interesting anomalous polarization and spin dynamics are observed, which is related to the interaction between the dark exciton state and the bright exciton fine structure. The spin-flip Raman scattering measurements on CsPbI3 NCs also reveal two g-factors, i.e. one is about 2.5 and another one about 1.5
Probing scalar meson structures in decays into pseudoscalar and scalar
We evaluate the decay branching ratios of , in a quark model
parametrization scheme, where and stand for pseudoscalar and scalar
meson, respectively. An interesting feature of this decay process is that the
annihilate via the pQCD hair-pin diagram is supposed to be dominant.
Hence, this decay process should be sensitive to the quark components of the
final-state light mesons, and would provide a great opportunity for testing the
mixing relations among the scalar mesons, i.e. , and
, by tagging the final state pseudoscalar mesons.Comment: 9 pages and 6 eps figures; Enhanced discussion on the dominance of
hair-pin diagram is added. Revised version to appear in IJMP
Holographic Schwinger effect with a moving D3-brane
We study the Schwinger effect with a moving D3-brane in a =4 SYM
plasma with the aid of AdS/CFT correspondence. We discuss the test particle
pair moving transverse and parallel to the plasma wind respectively. It is
found that for both cases the presence of velocity tends to increase the
Schwinger effect. In addition, the velocity has a stronger influence on the
Schwinger effect when the pair moves transverse to the plasma wind rather than
parallel.Comment: 8 pages, 6 figure
2-[4-(DimethylΒamino)phenΒyl]imidazo[4,5-f][1,10]phenanthroline sesquihydrate
There are two formula units in the asymmetric unit of the title compound, C21H17N5Β·1.5H2O. The imidazo[4,5-f][1,10]phenΒanΒthroline unit is almost coplanar with the benzene ring, the dihedral angles between them being 8.91β
(5) and 4.93β
(6)Β° in the two molΒecules. The crystal structure is stabilized by a series of hydrogen bonds between the water molΒecules and the N atoms of the imidazophenanthroline groups
Probing the nature of and in the isospin violating process
The isospin violation process is studied
assuming that is a hadronic molecule. In
association with the production of the , which is treated as a hadronic molecule, this process can help us distinguish their
molecular natures from other scenarios, since the incomplete cancellation
between the charged and neutral--meson loops, which are prominent in the
molecular picture only, produces a peak in the cross section at the threshold and a very
prominent peak in the invariant mass spectrum in between the thresholds; the latter being much narrower than the
corresponding one in the isospin conserving channel, i.e. . The partial width of is about of that of . The cross section of
at the threshold is
about which is much larger than that produced by the
nearby resonances. These features are the direct consequences of the assumed
nature of these two states which might be accessible at the high-statistics
experiments such as BESIII and LHCb.Comment: 11 pages, 4 figure
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