24,466 research outputs found
Finite volume corrections to the binding energy of the X(3872)
The quark mass dependence of hadrons is an important input for lattice
calculations. We investigate the light quark mass dependence of the binding
energy of the X(3872) in a finite box to next-to-leading order in an effective
field theory for the X(3872) with perturbative pions (XEFT). At this order, the
quark mass dependence is determined by a quark mass-dependent contact
interaction in addition to the one-pion exchange. While there is only a
moderate sensitivity to the light quark masses in the region up to twice their
physical value, the finite volume effects are significant already at box length
as large as 20 fm.Comment: 23 pages, 9 figures, REVTe
Cross-Correlation-Function-Based Multipath Mitigation Method for Sine-BOC Signals
Global Navigation Satellite Systems (GNSS) positioning accuracy indoor and urban canyons environments are greatly affected by multipath due to distortions in its autocorrelation function. In this paper, a cross-correlation function between the received sine phased Binary Offset Carrier (sine-BOC) modulation signal and the local signal is studied firstly, and a new multipath mitigation method based on cross-correlation function for sine-BOC signal is proposed. This method is implemented to create a cross-correlation function by designing the modulated symbols of the local signal. The theoretical analysis and simulation results indicate that the proposed method exhibits better multipath mitigation performance compared with the traditional Double Delta Correlator (DDC) techniques, especially the medium/long delay multipath signals, and it is also convenient and flexible to implement by using only one correlator, which is the case of low-cost mass-market receivers
SPSA-Based Tracking Method for Single-Channel-Receiver Array
A novel tracking method in the phased antenna array with a single-channel receiver for the moving signal source is presented in this paper. And the problems of the direction-of-arrival track and beamforming in the array system are converted to the power maximization of received signal in the free-interference conditions, which is different from the existing algorithms that maximize the signal to interference and noise ratio. The proposed tracking method reaches the global optimum rather than local by injecting the extra noise terms into the gradient estimation. The antenna beam can be steered to coincide with the direction of the moving source fast and accurately by perturbing the output of the phase shifters during motion, due to the high efficiency and easy implementation of the proposed beamforming algorithm based on the simultaneous perturbation stochastic approximation (SPSA). Computer simulations verify that the proposed tracking scheme is robust and effective
Electron-Phonon Interactions for Optical Phonon Modes in Few-Layer Graphene
We present a first-principles study of the electron-phonon (e-ph)
interactions and their contributions to the linewidths for the optical phonon
modes at and K in one to three-layer graphene. It is found that due to
the interlayer coupling and the stacking geometry, the high-frequency optical
phonon modes in few-layer graphene couple with different valence and conduction
bands, giving rise to different e-ph interaction strengths for these modes.
Some of the multilayer optical modes derived from the - mode of
monolayer graphene exhibit slightly higher frequencies and much reduced
linewidths. In addition, the linewidths of K- related modes in
multilayers depend on the stacking pattern and decrease with increasing layer
numbers.Comment: 6 pages,5 figures, submitted to PR
Deprojection technique for galaxy cluster considering point spread function
We present a new method for the analysis of Abell 1835 observed by
XMM-Newton. The method is a combination of the Direct Demodulation technique
and deprojection. We eliminate the effects of the point spread function (PSF)
with the Direct Demodulation technique. We then use a traditional depro-jection
technique to study the properties of Abell 1835. Compared to that of
deprojection method only, the central electron density derived from this method
increases by 30%, while the temperature profile is similar.Comment: accepted for publication in Sciences in China -- G, the Black Hole
special issu
Quantum dynamics of an Ising spin-chain in a random transverse field
We consider an Ising spin-chain in a random transverse magnetic field and
compute the zero temperature wave vector and frequency dependent dynamic
structure factor numerically by using Jordan-Wigner transformation. Two types
of distributions of magnetic fields are introduced. For a rectangular
distribution, a dispersing branch is observed, and disorder tends to broaden
the dispersion peak and close the excitation gap. For a binary distribution, a
non-dispersing branch at almost zero energy is recovered. We discuss the
relationship of our work to the neutron scattering measurement in
.Comment: 4 pages and 6 eps figures; minor clarifications were made; the text
was shortened to add an additional figur
Heavy Baryons in a Quark Model
A quark model is applied to the spectrum of baryons containing heavy quarks.
The model gives masses for the known heavy baryons that are in agreement with
experiment, but for the doubly-charmed baryon Cascade_{cc}, the model
prediction is too heavy. Mixing between the Cascade_Q and Cascade_Q^\prime
states is examined and is found to be small for the lowest lying states. In
contrast with this, mixing between the Cascade_{bc} and Cascade_{bc}^\prime
states is found to be large, and the implication of this mixing for properties
of these states is briefly discussed. We also examine heavy-quark spin-symmetry
multiplets, and find that many states in the model can be placed in such
multiplets. We compare our predictions with those of a number of other authors.Comment: Version published in International Journal of Modern Physics
Quenching and Tomography from RHIC to LHC
We compare fully perturbative and fully nonperturbative pictures of high-pT
energy loss calculations to the first results from LHC. While over-suppressed
compared to published ALICE data, parameter-free pQCD predictions based on the
WHDG energy loss model constrained to RHIC data simultaneously describe well
the preliminary CMS hadron suppression, ATLAS charged hadron v2, and ALICE D
meson suppression; we also provide for future reference WHDG predictions for B
meson RAA. However, energy loss calculations based on AdS/CFT also
qualitatively describe well the RHIC pion and non-photonic electron suppression
and LHC charged hadron suppression. We propose the double ratio of charm to
bottom quark RAA will qualitatively distinguish between these two energy loss
pictures.Comment: 4 pages, 3 figures. Proceedings for Quark Matter 201
Entanglement distribution maximization over one-side Gaussian noisy channel
The optimization of entanglement evolution for two-mode Gaussian pure states
under one-side Gaussian map is studied. Even there isn't complete information
about the one-side Gaussian noisy channel, one can still maximize the
entanglement distribution by testing the channel with only two specific states
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