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Decay width of d (2380) ! NN process in a chiral constituent quark model

Yubing Dong; Fei Huang; Pengnian Shen; Zongye Zhang分类： 物理学 >> 普通物理:统计和量子力学,量子信息等

The width of three-body single-pion decay process d∗ → NNπ0,± is calculated by using the d∗ wave function obtained from our chiral SU(3) constituent quark model calculation. The eﬀect of the dynamical structure on the width of d∗ is taken into account in both the single ∆∆ channel and cou-pled ∆∆+CC two-channel approximations. Our numerical result shows that in the coupled-channel approximation, namely, the hidden-color conﬁguration being considered, the obtained partial decay width of d∗ → NNπ is about several hundred KeV, while in the single ∆∆ channel it is just about 2 ∼ 3 MeV. We, therefore, conclude that the partial width in the single-pion decay process of d∗ is much smaller than the widths in its double-pion decay processes. Our prediction may provide a criterion for judging diﬀerent interpretations of the d∗ structure, as diﬀerent pictures for the d∗ may result quite diﬀerent partial decay width. |

分类： 物理学 >> 普通物理:统计和量子力学,量子信息等

A detailed theoretical derivation of the cross sections of e+e− → e+e− and e+e− → µ+µ− around the J/ψ resonance is reported. The resonance and interference parts of the cross sections, related to J/ψ resonance parameters, are calculated. Higher-order corrections for vacuum polarization and initial-state radiation are consid-ered. An arbitrary upper limit of radiative correction integration is involved. Full and simpliﬁed versions of analytic formulae are given with precision at the level of 0.1% and 0.2%, respectively. Moreover, the results obtained in the paper can be applied to the case of the ψ(3686) resonance. |

Modeling Charmonium-η Decays of JP C = 1−− Higher Charmonia

Muhammad Naeem Anwar; Yu Lu; Bing-Song Zou分类： 物理学 >> 普通物理:统计和量子力学,量子信息等

We propose a new model to create a light meson in the heavy quarkonium transition, which is inspired by the Nambu−Jona-Lasinio (NJL) model. Hadronic transitions of JPC = 1−− higher char-monia with the emission of an η meson are studied in the framework of the proposed model. The model shows its potential to reproduce the observed decay widths and make predictions for the unobserved channels. We present our predictions for the decay width of Ψ → J/ η and Ψ → hc(1P )η, where Ψ are higher S and D wave vector charmonia, which provide useful references to search for higher char-monia and determine their properties in forthcoming experiments. The predicted branching fraction B( (4415) → hc(1P )η) = 4.62 × 10−4 is one order of magnitude smaller than the J/ η channel. Esti-mates of partial decay width Γ(Y → J/ η) are given for Y (4360), Y (4390) and Y (4660) by assuming them as cc¯ bound states with quantum numbers 33D1, 33D1 and 53S1, respectively. Our results are in favor of these assignments for Y (4360) and Y (4660). The corresponding experimental data for these Y states has large statistical errors which do not provide any constraint on the mixing angle if we introduce S −D mixing. To identify Y (4390), precise measurements on its hadronic branching fraction are required which are eagerly awaited from BESIII. |

Is GW151226 a really signal of gravitational wave?

Zhe Chang; Chao-Guang Huang; Zhi-Chao Zhao分类： 物理学 >> 普通物理:统计和量子力学,量子信息等

Recently, the LIGO Scientiﬁc Collaboration and Virgo Collaboration published the second observation on gravitational wave GW151226 [Phys. Rev. Lett. 116, 241103 (2016)] from the binary black hole coalescence with initial masses about 14 M and 8 M. They claimed that the peak gravitational strain was reached at about 450 Hz, the inverse of which has been longer than the average time a photon staying in the Fabry-Perot cavities in two arms. In this case, the phase-diﬀerence of a photon in the two arms due to the propagation of gravitational wave does not always increase as the photon stays in the cavities. It might even be cancelled to zero in extreme cases. When the propagation eﬀect is taken into account, we ﬁnd that the claimed signal GW151226 would almost disappear. |

Power Law of Shear Viscosity in Einstein-Maxwell-Dilaton-Axion model

Yi Ling; Zhuoyu Xian; Zhenhua Zhou分类： 物理学 >> 普通物理:统计和量子力学,量子信息等

We construct charged black hole solutions with hyperscaling violation in the infrared(IR) region in Einstein-Maxwell-Dilaton-Axion theory and investigate the temperature behavior of the ratio of holographic shear viscosity to the entropy density. When translational symmetry breaking is relevant in the IR, the power law of the ratio is testi ed numerically at low temperature T, namely, =s T , where the values of exponent coincide with the analytical results. We also nd that the exponent is not a ected by irrelevant current, but is reduced by the relevant current. |

分类： 物理学 >> 普通物理:统计和量子力学,量子信息等

If massive neutrinos are Dirac particles, the proposed PTOLEMY experiment will hopefully be able to discover cosmic neutrino background via e+3H ! 3He+e with a capture rate of D 4 yr1. Recently, it has been pointed out that right-handed com-ponents of Dirac neutrinos could also be copiously produced in the early Universe and become an extra thermal or nonthermal ingredient of cosmic relic neutrinos, enhancing the capture rate to D 5:1 yr1 or D 6:1 yr1. In this work, we investigate the possibility to distinguish between thermal and nonthermal spectra of cosmic relic neu-trinos by measuring the annual modulation of the capture rate. For neutrino masses of 0:1 eV, we have found the amplitude of annual modulation in the standard case is M 0:05%, which will be increased to 0:1% and 0:15% in the presence of additional thermal and nonthermal right-handed neutrinos, respectively. The future detection of such a modulation will be helpful in understanding the Majorana or Dirac nature of massive neutrinos. |

Discussion on upper limit of the precision for τ mass measurement

X. H. Mo分类： 物理学 >> 凝聚态:结构、力学和热性能

τ lepton is one of three chareged leptons in nature, the measurements of its mass have been performed since its discovery. The present relative accuracy is already at the level of 10−4; more factors are still being studied in order to increase the accuracy. However, the available techniques for analysis and expectable luminosity from e+e− collider indicate that the precision upper limit of τ mass is almost reached, which means that brand new approaches should be looked for if the great improvement is yearned for. |

Data taking strategy for phase study through ψ′ → K+K− decay

Wang Boqun; Mo Xiaohu; Yuan Changzheng; Ban Yong分类： 物理学 >> 凝聚态:结构、力学和热性能

The study of the relative phase between strong and electromagnetic amplitudes is of great importance for understanding the dynamics of charmonium decays. The information of the phase can be obtained model-independently by fitting the scan data of some special decay channels, one of which is ψ′ → K+K−. To find out the optimal data taking strategy for a scan experiment in the phase study of ψ′ → K+K− decay, the minimization process is analyzed in detail from a theoretical point of view. |

On the leptonic partial widths of the excited ψ states

X. H. Mo; C. Z. Yuan; P. Wang分类： 物理学 >> 凝聚态:结构、力学和热性能

The resonance parameters of the excited ψ-family resonances, namely the ψ(4040), ψ(4160), and ψ(4415), were determined by fitting the R-values measured by experiments. It is found that the previously reported leptonic partial widths of these states were merely one possible solutions among a four-fold ambiguity. By fitting the most precise experimental data on the R-values measured by the BES collaboration, this work presents all four sets of solutions. These results may affect the interpretation of the charmonium and charmonium-like states above 4 GeV/c2. |

Multiple solutions in extracting physics information from experimental data

C. Z. Yuan; X. H. Mo; P. Wang分类： 物理学 >> 凝聚态:结构、力学和热性能

Multiple solutions exist in many experimental situations when several interfering amplitudes are summed to fit experimentally measured distributions, such as cross sections, mass spectra, and/or the angular distributions. We show a few examples where multiple solutions are found, but only one solution is reported in the publications. Since there is no standard rule for choosing one among the solutions as the physics one, we propose a simple rule that agrees with what has been adopted in previous literatures: the solution corresponding to the minimal magnitudes of the amplitudes must be the physical solution. We suggest test this rule in the future analyses. |