10,321 research outputs found
Fully open-flavor tetraquark states and with
We have studied the masses for fully open-flavor tetraquark states
and with quantum numbers
. We systematically construct all diquark-antiquark
interpolating currents and calculate the two-point correlation functions and
spectral densities in the framework of QCD sum rule method. Our calculations
show that the masses are about GeV for the
tetraquark states and GeV for the tetraquarks. The
masses of tetraquarks are below the thresholds of
and final states for the scalar and
axial-vector channels respectively. The tetraquark states
with lie below the and thresholds.
Such low masses for these possible tetraquark states indicate that they can
only decay via weak interaction and thus are very narrow and stable.Comment: 17 pages, 4 figure
Conical Defects, Black Holes and Higher Spin (Super-)Symmetry
We study the (super-)symmetries of classical solutions in the higher spin
(super-)gravity in AdS. We show that the symmetries of the solutions are
encoded in the holonomy around the spatial circle. When the spatial holonomies
of the solutions are trivial, they preserve maximal symmetries of the theory,
and are actually the smooth conical defects. We find all the smooth conical
defects in the , as well as in
and Chern-Simons gravity theories. In the bosonic higher spin
cases, there are one-to-one correspondences between the smooth conical defects
and the highest weight representations of Lie group. Furthermore we investigate
the higher spin black holes in and higher spin
(super-)gravity and find that they are only partially symmetric. In general,
the black holes break all the supersymmetries, but in some cases they preserve
part of the supersymmetries.Comment: 48 pages; more clarifications on conical defects in supersymmetric
cas
Black holes in Truncated Higher Spin AdS Gravity
We study the higher spin black holes in a truncated version of higher spin
gravity in . This theory contains only finite number of even spins
s=2,4,...,2N. We mainly focus on the simplest case, so-called (Type I and II)
spin gravity, which contains only spin 2 and spin 4 fields. This
spin gravity is as simple as spin 3 gravity, thus provides another
example to test various ideas on higher spin gravity. We find that the
asymptotical symmetry of this spin gravity is a classical
W(2,4)-symmetry. Moreover, we study the black hole solution with pure spin 4
hair and discuss its thermodynamics. One important feature of this black hole
is that its entropy could be written in compact forms. Furthermore, we
investigate a generated higher spin gravity. This higher spin gravity
only contains spin 2 and spin 6 fields which makes it different from other
kinds of higher spin gravity. We find the corresponding black hole with spin 6
hair, and discuss its thermodynamics analytically. It turns out that the black
holes with spin 4 or spin 6 hair constructed in this paper are the only black
holes with single higher spin hair, besides the spin 3 black hole found in
arXiv:1103.4304.Comment: 23 pages;minor revision, references added; published versio
Energy-Efficient Transmission Schedule for Delay-Limited Bursty Data Arrivals under Non-Ideal Circuit Power Consumption
This paper develops a novel approach to obtaining energy-efficient
transmission schedules for delay-limited bursty data arrivals under non-ideal
circuit power consumption. Assuming a-prior knowledge of packet arrivals,
deadlines and channel realizations, we show that the problem can be formulated
as a convex program. For both time-invariant and time-varying fading channels,
it is revealed that the optimal transmission between any two consecutive
channel or data state changing instants, termed epoch, can only take one of the
three strategies: (i) no transmission, (ii) transmission with an
energy-efficiency (EE) maximizing rate over part of the epoch, or (iii)
transmission with a rate greater than the EE-maximizing rate over the whole
epoch. Based on this specific structure, efficient algorithms are then
developed to find the optimal policies that minimize the total energy
consumption with a low computational complexity. The proposed approach can
provide the optimal benchmarks for practical schemes designed for transmissions
of delay-limited data arrivals, and can be employed to develop efficient online
scheduling schemes which require only causal knowledge of data arrivals and
deadline requirements.Comment: 30 pages, 7 figure
Security enhancement using a novel two-slot cooperative NOMA scheme
In this letter, we propose a novel cooperative non-orthogonal multiple access (NOMA) scheme to guarantee the secure transmission of a specific user via two time slots. During the first time slot, the base station (BS) transmits the superimposed signal to the first user and the relay via NOMA. Meanwhile, the signal for the first user is also decoded at the second user from the superimposed signal due to its high transmit power. In the second time slot, the relay forwards the signal to the second user while the BS retransmits the signal for the first user as interference to disrupt the eavesdropping. Due to the fact that the second user has obtained the signal for the first user in the first slot, the interference can be eliminated at the second user. To measure the performance of the proposed cooperative NOMA scheme, the outage probability for the first user and the secrecy outage probability for the second user are analyzed. Simulation results are presented to show the effectiveness of the proposed scheme
Robust federated learning with noisy communication
Federated learning is a communication-efficient training process that alternate between local training at the edge devices and averaging of the updated local model at the center server. Nevertheless, it is impractical to achieve perfect acquisition of the local models in wireless communication due to the noise, which also brings serious effect on federated learning. To tackle this challenge in this paper, we propose a robust design for federated learning to decline the effect of noise. Considering the noise in two aforementioned steps, we first formulate the training problem as a parallel optimization for each node under the expectation-based model and worst-case model. Due to the non-convexity of the problem, regularizer approximation method is proposed to make it tractable. Regarding the worst-case model, we utilize the sampling-based successive convex approximation algorithm to develop a feasible training scheme to tackle the unavailable maxima or minima noise condition and the non-convex issue of the objective function. Furthermore, the convergence rates of both new designs are analyzed from a theoretical point of view. Finally, the improvement of prediction accuracy and the reduction of loss function value are demonstrated via simulation for the proposed designs
On the English Translation of Tang Poetry in the Perspective of “Harmony-Guided Three-level Poetry Translation Criteria”—A Case Study of “Song of the Roosting Crows”
The translation of ancient Chinese poetry has always been an insurmountable mountain in literary translation, and Li Bai\u27s poetic merits as a unique symbol of ancient Chinese poetry are more favored by Chinese and foreign translators. Some of the translations are to an extent mixed with drawbacks. Based on Dr. Wang Feng’s “Harmony-guided Three-Level poetry translation criteria”, this paper compares and analyzes four English versions of Li Bai’s “Song of the Roosting Crows”. It demonstrates the practical value of this theory in Chinese poetry translation, hoping to promote the dissemination of Chinese literature and culture
- …