119303730
Annihilation Rate of Heavy 0^{++} P-wave Quarkonium in Relativistic Salpeter Method
Abstract Two-photon and two-gluon annihilation rates of P-wave scalar charmonium and bottomonium up to third radial excited states are estimated in the relativistic Salpeter method. We solved the full Salpeter equation with a well defined relativistic wave function and calculated the transition amplitude using the Mandelstam formalism. Our model dependent estimates for the decay widths: Γ(χc0 → 2γ) = 3.78 keV, Γ(χ′c0 → 2γ) = 3.51 keV, Γ(χb0 → 2γ) = 48.8 eV and Γ(χ′b0 → 2γ) = 50.3 eV. We also give estimates of total widths by the two-gluon decay rates: Γtot(χc0) = 10.3 MeV, Γtot(χ ′ c0) = 9.61 MeV, Γtot(χb0) = 0.887 MeV and Γtot(χ ′ b0) = 0.914 MeV.
15593532
Decay constants of heavy vector mesons in relativistic Bethe-Salpeter method
Abstract In a previous Letter, we computed the decay constants of heavy pseudoscalar mesons in the framework of relativistic (instantaneous) Bethe–Salpeter method (full 0 − Salpeter equation), in this Letter, we solve the full 1 − Salpeter equation and compute the leptonic decay constants of heavy–heavy and heavy–light vector mesons. The theoretical estimate of mass spectra of these heavy–heavy and heavy–light vector mesons are also presented. Our results for the decay constants and mass spectra include the complete relativistic contributions. We find F D s ∗ ≈ 375 ± 24 , F D ∗ ≈ 340 ± 23 ( D ∗ 0 , D ∗ ± ) , F B s ∗ ≈ 272 ± 20 , F B ∗ ≈ 238 ± 18 ( B ∗ 0 , B ∗ ± ) , F B c ∗ ≈ 418 ± 24 , F J / Ψ ≈ 459 ± 28 , F Ψ ( 2 S ) ≈ 364 ± 24 , F ϒ ≈ 498 ± 20 and F ϒ ( 2 S ) ≈ 366 ± 27 MeV .
15948978
The Pure Leptonic Decays of $D_s$ Meson and Their Radiative Corrections
The radiative corrections to the pure leptonic decay $D_s{\longrightarrow} {\ell}{{\nu}}_{\ell}$ up-to one-loop order is presented. We find the virtual photon loop corrections to $D_s{\longrightarrow} {\tau}{{\nu}}_{\tau}$ is negative and the corresponding branching ratio is larger than $3.51\times 10^{-3}$. Considering the possible experimental resolutions, our prediction of the radiative decay $D_s{\longrightarrow} {\tau}{{\nu}}_{\tau}\gamma$ is not so large as others, and the best channel to determine the $V_{cs}$ or $f_{D_s}$ is $D_s{\longrightarrow} {\mu}{{\nu}}_{\mu}{\gamma}$. How to cancel the infrared divergences appearing in the loop calculations, and the radiative decay $D_s{\longrightarrow} {\ell}{{\nu}}_{\ell}{\gamma}$ is shown precisely. It is emphasized that the radiative decay may be separated properly and may compare with measurements directly as long as the theoretical `softness' of the photon corresponds to the experimental resolutions.
123969406
Semileptonic Production of Scalar and Tensor p-Wave Charmed Mesons
With the same constituents of quark and antiquark, the p-wave state has a higher mass than the corresponding s-wave state, but the relativistic corrections are much larger in the processes of which p-wave mesons are involved. Considering this, the relativistic Bethe?Salpeter method is applied to estimate the branching fractions of semileptonic decays B(s) ? D*(sJ)l? (J = 0,2). Our predictions are Br[???(2317)l?]?=?0.50%, Br[???(2573)l?]?=?0.40%, Br[B????(2400)l?]?=?0.79%, Br[B????(2460)l?]?=?0.28%, Br[???(2400)l?]?=?0.58% and Br[???(2460)l?]?=?0.27%. .
119163636
Decay constants of P-wave mesons
Abstract Decay constants of P-wave mesons are computed in the framework of instantaneous Bethe–Salpeter method (Salpeter method). By analyzing the parity and possible charge conjugation parity, we give the relativistic configurations of wave functions with definite parity and possible charge conjugation parity. With these wave functions as input, the full Salpeter equations for different P-wave states are solved, and the mass spectra as well as the numerical values of wave functions are obtained. Finally we compute the leptonic decay constants of heavy–heavy and heavy–light P 0 3 , P 1 3 and P 1 1 states.
119300428
Why X(3915) is so narrow as a $\chi_{c0}(2P)$ state
New resonance X(3915) was identified as the charmonium $\chi_{c0}(2P)$ by BABAR Collaboration, but there seems still open question of this assignment: why its full width is so narrow? To answer this question, we calculate the Okubo-Zweig-Iizuka (OZI) allowed strong decays $X(3915)\to D \bar D$, where X(3915) is assigned as a $\chi_{c0}(2P)$ state, and estimate its full width in the cooperating framework of $^3/!P_0^{}$ model and the Bethe-Salpeter (BS) method using the Mandelstam Formalism, during which non-perturbative QCD effects of the hadronic matrix elements are well considered by overlapping integral over the relativistic Salpeter wave functions of the initial and finial states. We find the node structure of $\chi_{c0}(2P)$ wave function resulting in the narrow width of X(3915) and show the dependence of the decay width on the variation of the initial mass of X(3915). We point out that the rate of $\frac{\Gamma(X(3915)\to D^+ D^-)}{\Gamma(X(3915)\to D^0 \bar D^0)}$ is crucial to confirm whether X(3915) is the $\chi_{c0}(2P)$ state or not.
122537214
Search for local parity violation with STAR ZDC-SMD
Parity-odd domains are predicted to lead to charge separation of quarks along the orbital momentum of the system created in non-central relativistic heavy ion collisions. A signal consistent with several of the theoretical expectations has been detected by STAR, with a three particle azimuthal correlator which is a -even observable, but still sensitive to the charge separation effect. In this correlator, the first two particles are used to reveal the physics of interest, and the third particle serves as a reference for the reaction plane. In this work, to minimize the non-parity correlation between the third particle and the first two, we utilize the spectator neutrons detected by STAR ZDC-SMDs to define the event plane. The 1st-order event plane thus obtained can also be used to study the global strong parity violation effect, and to provide further systematic checks for this analysis. We report measurements of both -even and -odd observables using the STAR ZDC-SMDs in Au+Au at 200 GeV. The results are presented as a function of collision centrality, particle separation in rapidity and transverse momentum (pT). Systematic checks on the impact from the directed flow will also be discussed.
14494427
Highlights from STAR: probing the early medium in heavy ion collisions
Abstract We present highlights of recent results from the STAR Collaboration at RHIC, focusing on the properties of the early medium created in heavy ion collisions. We emphasize the strangeness production including the observation of a hypernucleus (the hypertriton), the observation of reaction-plane-dependent angular correlation of charged particles searching for local strong parity violation effects in heavy ion collisions, and the evaluation of the medium viscosity from measurements of elliptic flow. We discuss STAR's plan for the “Critical Point Search” program at RHIC.
107782453
Reducing the Impedance of the Flange Gaps in BEPC Vacuum Chamber
120678530
A Monte Carlo model for diffractive dissociation in hadron-hadron collisions at high energies
We present a Monte Carlo generator for single diffractive dissociation in hadron-hadron collisions at high energies. The generator, which is based on some kinematic consideration and involves the minimum of theoretical hypothesis, reproduces the experimental data. Such a generator is useful to study the phenomenology of diffractive processes and to explore important roles of diffractive processes in cosmic ray interaction and propagation in the atmosphere and in interstellar space.
122315733
Coordinates problem of Hawking radiation derivation in a Kerr–Newman black hole using Hamilton–Jacobi equation
Hawking radiation from a Kerr–Newman black hole is investigated using Hamilton–Jacobi method more deeply. A direct computation will lead to a wrong result via Hamilton–Jacobi method. However, when the well-behaved Painleve coordinate system and Eddington coordinate system are considered, we can get the correct result. The reason of the discrepancy between naive coordinate and well-behaved coordinates is also discussed.