2,806 research outputs found
The Effects of Minimal Length, Maximal Momentum and Minimal Momentum in Entropic Force
In this paper, the modified entropic force law is studied by using a new kind
of generalized uncertainty principle which contains a minimal length, a minimal
momentum and a maximal momentum. Firstly, the quantum corrections to the
thermodynamics of a black hole is investigated. Then, according to Verlinde's
theory, the generalized uncertainty principle (GUP) corrected entropic force is
obtained. The result shows that the GUP corrected entropic force is related not
only to the properties of the black holes, but also to the Planck length and
the dimensionless constants and . Moreover,
based on the GUP corrected entropic force, we also derive the modified
Einstein's field equation (EFE) and the modified Friedmann equation.Comment: 16 pages. arXiv admin note: substantial text overlap with
arXiv:1604.0470
LOWER DEVONIAN (PRAGIAN) BRACHIOPODS FROM THE DASHATIAN SECTION, GUANGXI, SOUTH CHINA
Lower Devonian brachiopods in South China are very rare since most areas lack deposits owing to an uplift movement of the Guangxi (Caledonian) Orogeny. In this paper, we describe a brachiopod fauna consisting of 13 species in 12 genera from the Nagaoling Formation at the Dashatian section in the suburb area of the Nanning City, Guangxi, South China. This fauna is dominated by small rhynchonellide and spiriferide species, along with chonetidines, strophomenides, atrypides, athyridides and others. The early Pragian age for the brachiopod-bearing horizons in the Nagaoling Formation is constrained by the associated early Pragian conodonts Eognathodus sulcatus Zone. About 33% genera of the brachiopod fauna are endemic to South China, therefore they do not provide any clear evidence for its paleobiogeographical link to the faunas of Europe, Australia, or North America. This fauna is paleoecologically interpreted as being deposited in a shallow, oxygen-rich, low to moderate energy, subtidal palaeoenvironment in the early Pragian and it corresponds to the benthic assemblage BA2 to upper BA
Photospheric velocity evolution of SN 2020bvc: signature of -process nucleosynthesis from a collapsar
Whether binary neutron star mergers are the only astrophysical site of rapid
neutron-capture process (-process) nucleosynthesis remains unknown.
Collapsars associated with long gamma-ray bursts (GRBs) and hypernovae are
promising candidates. Simulations have shown that outflows from collapsar
accretion disks can produce enough -process materials to explain the
abundances in the universe. However, there is no observational evidence to
confirm this result at present. SN 2020bvc is a broad-lined type Ic (Ic-BL)
supernova (SN) possibly associated with a low-luminosity GRB. Based on
semi-analytic SN emission models with and without -process materials, we
perform a fitting to the multi-band light curves and photospheric velocities of
SN 2020bvc. We find that in a -process-enriched model the mixing of
-process materials slows down the photospheric recession and therefore
matches the velocity evolution better. The fitting results show that
-process materials with mass of and opacity of
is needed to mix with about half of the SN ejecta.
Our fitting results are weakly dependent on the nebular emission. Future
statistical analysis of a sample of type Ic-BL SNe helps us understand the
contribution of collapsars to the -process abundance.Comment: 16 Pages, 9 Figures, 2 Tables, Accepted by ApJ
GRB 211211A: a Neutron StarWhite Dwarf Merger?
The gamma-ray burst GRB 211211A and its associated kilonova-like emission
were reported recently. A significant difference between this association event
and GRB 170817A/AT 2017gfo is that GRB 211211A has a very long duration. In
this paper, we show that this association event may arise from a neutron
starwhite dwarf (NSWD) merger if a magnetar leaves finally in the central
engine. Within the NSWD merger, the main burst of GRB 211211A could be
produced by magnetic bubble eruptions from toroidal magnetic field
amplification of the pre-merger NS. This toroidal field amplification can be
induced by the runaway accretion from the WD debris disc if the disc is in low
initial entropy and efficient wind. While the extended emission of GRB 211211A
is likely involved with magnetic propelling. The observed energetics and
duration of the prompt emission of GRB 211211A can be fulfilled in comparison
with those of accretion in hydrodynamical thermonuclear simulation, as long as
the WD has a mass . Moreover, if the X-ray plateau in GRB
afterglows is due to the magnetar spin-down radiation, GRB optical afterglows
and kilonova-like emission can be well jointly modeled combining the standard
forward shock with the radioactive decay power of adding a
rotational power input from the post-merger magnetar.Comment: Accepted by ApJ Letters. The accretion rate can be
>0.01 if the WD debris disc is in low initial entropy
simulated by Kaltenborn et al. (2022). Main burst vs. extended emission:
accretion vs. propelling. Kilonova-like emission: magnetar-fed powe
Generic Friedberg-Lee Symmetry of Dirac Neutrinos
We write out the generic Dirac neutrino mass operator which possesses the
Friedberg-Lee (FL) symmetry and find that its corresponding neutrino mass
matrix is asymmetric. Following a simple way to break the FL symmetry, we
calculate the neutrino mass eigenvalues and show that the resultant neutrino
mixing pattern is nearly tri-bimaximal. Imposing the Hermitian condition on the
neutrino mass matrix, we also show that the simplified ansatz is consistent
with current experimental data and favors the normal neutrino mass hierarchy.Comment: RevTex4 10 pages, 1 figur
2,2′-[1-(2,4,6-Trichlorophenyl)-1H-1,2,4-triazole-3,5-diyl]diphenol
The title compound, C20H12Cl3N3O2, was synthesized by the reaction of 2-(2-hydroxyÂphenÂyl)benz[e][1,3]oxazin-4-one with 2,4,6-trichloroÂphenylÂhydrazine in ethanol. The trichloroÂphenyl ring is nearly perpendicular to the triazole plane [dihedral angle 80.56 (8)°], whereas the two hydroxyÂphenyl rings are approximately coplanar with the triazole ring [dihedral angles of 2.79 (12) and 8.00 (14)°]. IntraÂmolecular O—H⋯N hydrogen bonding is observed between the hydroxyÂphenyl and triazole rings
Methyl 5-[N,N-bisÂ(methoxyÂcarbonylÂmethÂyl)amino]-4-cyano-2-methoxyÂcarbonyl-3-thioÂpheneÂethanÂoÂate
In the title compound, C16H18N2O8S, derived from ranelic acid, there is a highly substituted thioÂphene ring. The crystal structure involves interÂmolecular C—H⋯O and C—H⋯S hydrogen bonds
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