119273649
The radiative decays $B_{c}^{*\pm} \to B_{c}^{\pm} \gamma$ with QCD sum rules
In this article, we calculate the $B_{c}^{*} \to B_{c}$ electromagnetic form-factor with the three-point QCD sum rules and then study the radiative decays $B_{c}^{*\pm} \to B_{c}^{\pm} \gamma$. Experimentally, we can study the radiative transitions using the decay cascades $B_{c}^{*\pm}\to B_{c}^{\pm} \gamma\to J/\psi\ell^{\pm}\bar{\nu}_{\ell} \gamma\to\mu^{+} \mu^{-} \ell^{\pm}\bar{\nu}_{\ell} \gamma$ in the future at the LHCb.
120311946
Final state interactions in the decay B0 ---> eta(c)K*
119121085
ANALYSIS OF THE $B \to K^*_2(1430), a_2(1320), f_2(1270)$ FORM-FACTORS WITH LIGHT-CONE QCD SUM RULES
In this paper, we study the form-factors with the light-cone QCD sum rules, where the B-meson light-cone distribution amplitudes are used. In calculations, we observe that the line-shapes of the B-meson light-cone distribution amplitude ϕ+(ω) have significant impacts on the values of the form-factors, and expect to obtain severe constraints on the parameters of the B-meson light-cone distribution amplitudes from the experimental data in the future.
15122700
Analysis of the Y(2175) as a tetraquark state with QCD sum rules
Abstract In this article, we take the point of view that Y ( 2175 ) be a tetraquark state which consists of color octet constituents, and calculate its mass and decay constant within the framework of the QCD sum rule approach. We release standard criterion in the QCD sum rules approach and take more phenomenological analysis, the value of the mass of Y ( 2175 ) is consistent with experimental data; there may be some tetraquark components in the state Y ( 2175 ) . If we retain standard criterion, larger mass than experimental data can be obtained, the current J μ ( x ) can interpolate a tetraquark state with larger mass, or Y ( 2175 ) has some components with larger mass. The dominating contribution comes from the perturbative term, which is in contrast to the sum rules with interpolating currents constructed from diquark pairs. The tetraquark states may consist of color octet constituents rather than diquark pairs.
118430852
Analysis of mass difference of the $\pi$ and $\rho$ with Bethe-Salpeter equation
In this article, we take into account the one-pion exchange force besides the onegluon exchange force to study the mass difference of the π and ρ mesons with the Bethe-Salpeter equation. After projecting the Bethe-Salpeter equation into an simple form, we can see explicitly that the bound energy |Eπ| ≫ |Eρ|. PACS number: 12.39.Ki, 12.39.Pn
15232561
Reanalysis of the mass spectrum of the scalar hidden charm and hidden bottom tetraquark states
In this article, we study the mass spectrum of the scalar hidden charm and hidden bottom tetraquark states which consist of the axial-vector–axial-vector type and the vector–vector type diquark pairs with the QCD sum rules.
117063918
Recent physics results at BES
¢ 2 S£ and 33 pb¤ 1 ψ ¥¥ events collected at BES-II detector, some charm physics results are obtained. In J ¡ ψ decay, we observed an unknown resonance X(1835) and study the controversial particle σ and κ. In ψ ¢ 2 S£ decay, we test the " 12% rule " via many decay modes and find many new χ cJ decay channels. In ψ ¥¥ decay, we observed the non-D ¯ D decay via ψ ¥¥ § ¦ π ¨ π ¤ J ¡ ψ and study the semi-leptonic decay of D meson. In addition, we give the preliminary ψ ¥¥ resonance parameters with higher precision. c Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence.
99565521
Study of the psi(2S) decay to p anti-p pi+ pi- (pi0)
16091296
Dielectron cross-section measurements in nucleus-nucleus reactions at 1-A/GeV
We present measured dielectron production cross sections for Ca+Ca, C+C, He+Ca, and d+Ca reactions at 1.0 A GeV . Statistical uncertainties and systematic effects are smaller than in previous dilepton spectrometer (DLS) nucleus-nucleus data. For pair mass M{le}0.35 GeV/c{sup 2} we obtain (1) the Ca+Ca cross section is larger than the previous DLS measurement and current model results, (2) the mass spectra suggest large contributions from {pi}{sup 0} and {eta} Dalitz decays, and (3) d{sigma}/dM{proportional_to}A{sub P}A{sub T}. For M{gt}0.5 GeV/c{sup 2} the Ca+Ca to C+C cross section ratio is significantly larger than the ratio of A{sub P}A{sub T} values. {copyright} {ital 1997} {ital The American Physical Society}
8434175
X-Ray Observation and Analysis of the Composite Supernova Remnant G327.1–1.1
Based on the data from the observation of the supernova remnant (SNR) G327.1-1.1 by the Advanced Satellite for Cosmology and Astrophysics (ASCA) and ROSAT, we find that G327.1-1.1 is a composite remnant with both a nonthermal emission component and a diffuse thermal emission component. The nonthermal component is well fitted by a power-law model with photon index Γ~2.2. This component is attributed to the emission from the synchrotron nebula powered by an undiscovered central pulsar. The thermal component has a temperature of about 0.4 keV. We attribute it to the emission from the shock-heat swept-up interstellar medium (ISM). Its age, explosion energy, and density of ambient medium are derived from the observed thermal component. Some characteristics of the synchrotron nebula are also derived. We have searched for the pulsed signal but have not found it. The soft X-ray (0.4-2 keV) and hard X-ray (2-10 keV) images are different, but they both elongate in the southeast-northwest direction. And this X-ray southeast-northwest elongation is in positional coincidence with the radio ridge in the Molonglo Observatory Synthesis Telescope (MOST) 843 MHz radio map. We present a possibility that the X-ray nonthermal emission mainly comes from the trail produced by a quickly moving undiscovered pulsar, and the long radio ridge is formed when the pulsar is moving out of the boundary of the plerionic structure.
56250567
Macroscopic Klein tunneling in spin-orbit-coupled Bose-Einstein condensates
We propose an experimental scheme to detect macroscopic Klein tunneling with spin-orbit coupled Bose-Einstein condensates (BECs). We show that a nonlinear Dirac equation with tunable parameters can be realized with such BECs. %in a simple configuration to generate the artificial spin-orbit coupling. Through numerical calculations, we demonstrate that macroscopic Klein tunneling can be clearly detected under realistic conditions. Macroscopic quantum coherence in such relativistic tunneling is clarified and a BEC with a negative energy is shown to be able to transmit transparently through a wide Gaussian potential barrier.