10,032 research outputs found
Weak Decays of Doubly-Heavy Tetraquarks
We study the weak decays of exotic tetraquark states
with two heavy quarks. Under the SU(3) symmetry for light quarks, these
tetraquarks can be classified into an octet plus a singlet: . We will concentrate on the octet tetraquarks with
, and study their weak decays, both semileptonic and nonleptonic.
Hadron-level effective Hamiltonian is constructed according to the irreducible
representations of the SU(3) group. Expanding the Hamiltonian, we obtain the
decay amplitudes parameterized in terms of a few irreducible quantities. Based
on these amplitudes, relations for decay widths are derived, which can be
tested in future. We also give a list of golden channels that can be used to
look for these states at various colliders.Comment: 14 pages,3 figure
The likely Fermi Detection of the Supernova Remnant RCW 103
We report on the results from our -ray analysis of the supernova
remnant (SNR) RCW 103 region. The data were taken with the Large Area Telescope
on board the Fermi Gamma-ray Space Telescope. An extended source is found at a
position consistent with that of RCW 103, and its emission was only detected
above 1 GeV (10 significance), having a power-law spectrum with a
photon index of 2.00.1. We obtain its 1--300 GeV spectrum, and the total
flux gives a luminosity of 8.3 erg s at a source
distance of 3.3 kpc. Given the positional coincidence and property similarities
of this source with other SNRs, we identify it as the likely Fermi -ray
counterpart to RCW 103. Including radio measurements of RCW 103, the spectral
energy distribution (SED) is modeled by considering emission mechanisms based
on both hadronic and leptonic scenarios. We find that models in the two
scenarios can reproduce the observed SED, while in the hadronic scenario the
existence of SNR--molecular-cloud interaction is suggested as a high density of
the target protons is required.Comment: 6 pages, 3 figures, accepted for publication in Ap
Protecting entanglement from correlated amplitude damping channel using weak measurement and quantum measurement reversal
Based on the quantum technique of weak measurement, we propose a scheme to
protect the entanglement from correlated amplitude damping decoherence. In
contrast to the results of memoryless amplitude damping channel, we show that
the memory effects play a significant role in the suppression of entanglement
sudden death and protection of entanglement under severe decoherence. Moreover,
we find that the initial entanglement could be drastically amplified by the
combination of weak measurement and quantum measurement reversal even under the
correlated amplitude damping channel. The underlying mechanism can be
attributed to the probabilistic nature of weak measurements.Comment: 11 pages, 5 figures, accepted by Quantum Information Processin
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