The Λ-type P-wave bottom baryon states via the QCD sum rules

Our study focuses on the Λ-type P-wave bottom baryon states with spin-parity JP=1/2−, 3/2−. We introduce an explicit P-wave between the two light quarks in the interpolating currents (these light quarks are antisymmetric in the flavor space, thus giving rise to the designation of Λ-type baryon) to investigate the Λb and Ξ_(b) states within the framework of the full QCD sum rules. The predicted masses show that Ξ_(b)(6087) and Ξ_(b)(6095/6100) could be the P-wave bottom-strange baryon states with spin-parity JP=1/2− and 3/2−, respectively;meanwhile, Λb(5912) and Λb(5920) could be the P-wave bottom baryon states with spin-parity JP=1/2− and 3/2−, respectively. Moreover, Λb(5920) and Ξ_(b)(6095/6100) may have two remarkable under-structures or Fock components at least.

Analysis of the Triply Heavy Baryon States with QCD Sum Rules

In this article, we study the (1/2) ± and (3/2)± triply heavy baryon states in a systematic way by subtracting the contributions from the corresponding (1/2)■ and (3/2)■ triply heavy baryon states with the QCD sum rules, and make reasonable predictions for their masses.

The Cosmological Evolution of Baryonic Matter’S Density Perturbations Under Influence of the Quintessence

For deeper understanding the process of baryonic matter evolution in the expanding Universe it is necessary to know the physical property of concrete field that represents the background of substrate type of dark energy. Beside, it is necessary to explore in details the influence of such field on the continuous medium of baryonic matter. These statements were realized for the quintessence field that describes by two gravitating scalar fields. They give own contributions at the total pressure and at the total mass density of baryonic matter. It allowed show that evolution of baryonic matter’s density perturbations obeys the equation of forced oscillations and admits the resonance case, when amplitude of baryonic matter’s density perturbations gets the strong short-time splash. This splash interprets as a new macroscopic mechanism of the initial matter density perturbations appearance.

在Y′-c_3表示及Y″-t_3表示中重子磁矩计算

给出了在旋量交换下的 Y′-c_3表示及 Y″-t_3表示中满足 SU(3)亚群对称条件下,含有 s、c 及 t、b 夸克组分的重子磁矩.

在Y'-C_3表示中重子及介子的质量谱

给出了在旋量变换下的Ｙ＇－Ｃ３表示中，满足ＳＵ（３）亚群对称条件下，含有Ｓ、Ｃ夸克组成的重子态及介子态的质量。

在■′-c_3表示中SU_f(3)亚群对称及重子磁矩

通过旋量变换及平移变换,给出了■-c_3表示中满足 SU_f(3)亚群对称的夸克组态,计算了可能存在的由这些夸克组成相应重子混合对称和全对称态的磁矩.

B介子系统CP破坏研究

本文对B介子系统进行了全面系统的研究,计算了Bd与Bs到各种可能双重子未态衰变过程中的cp破坏效应。我们的结论是:Bs系统中存在大的混合效应,但cp破坏的不对称号参数较小,实验上难以探测到。Bd系统中,B_d^o(■_d^o)→P过程是观测cp破坏的最有希望的反应道,观察到cp破坏需b对数甘为10~8。

在Y′-c3表示中SU_f(3)亚群对称及重子磁矩

通过旋量变换及平移变换，给出了Ｙ′ｃ３表示中满足ＳＵｆ（３）亚群对称的夸克组态，计算了可能存在的由这些夸克组成相应重子混合对称和全对称态的磁矩．

在Y′-c_3表示及Y″-t_3表示中重子磁矩计算

给出了在旋量交换下的Ｙ′－ｃ３表示及Ｙ″－ｔ３表示中满足ＳＵ（３）亚群对称条件下，含有ｓ、ｃ及ｔ、ｂ夸克组分的重子磁矩．

重子谱现状及兰州CSR可开展的N研究项目(英文)

概述了重子谱研究现状及在北京正负电子对撞机通过J/Ψ衰变开展重子谱研究的最新进展.探讨了在兰州CSR可开展的核子激发态研究项目.

ρ介子对中子星物态方程的影响

在相对论平均场理论框架内采用σ-ω-ρ模型进行数值计算,确定引入ρ介子对中子星能量密度和压强变化的影响,进而研究其对中子星壳层的物态方程的影响。计算结果表明:ρ介子使中子星能量密度随着重子数密度的增大而增大,同时压强也随着重子数密度的增大而变化更大更显著,从而使中子星的物态方程变硬。

三体相互作用与重子谱

计算了三体相互作用势在ＳＵ（６）对称态中的平均值，研究了三体相互作用势对重子谱的影响．所得到的能谱与实验符合得较好，表明三体相互作用势的影响是不能忽略的．

BABAR measurement of baryon time-like form factors via initial state radiation

BABAR has measured with unprecedented accuracy the e^＋e^- → pp and e^＋e^- →∧∧ cross sections by means of the initial state radiation technique, which has the advantages of good efficiency, good energy resolution and full angular acceptance, even exactly at threshold. A peculiar feature of these cross sections is their non-vanishing values at threshold. In the case of charged baryons, this phenomenon is expected according to the Coulomb interaction between the outgoing baryon and antibaryon. Once this Coulomb enhancement factor is taken into account, the striking result is achieved that the proton form factor at threshold is ｜GP（4Mp^2）｜ = 1, that is what is expected for pointlike fermion pairs, in spite of the proton structure. However a Coulomb enhancement factor is not expected for neutral fermions, likely in contradiction with the BABAR data. Qualitatively this behaviour is consistent with Coulomb interactions at the valence quark level.

Analysis of the excited Ω_(c) states as the 1/2^(±) pentaquark states with QCD sum rules

We construct both the scalar-diquark-scalar-diquark-antiquark type and axialvector-diquark-axialvector-diquark-antiquark type interpolating currents to study the charmed pentaquark:states suscu with J^(p)=1/2^(±).We employ the QCD sum rules to investigate the masses and pole residues of the charmed pentaquark states by taking into account the vacuum condensates up to dimension 13 in the operator product expansion.Our calculation results indicate that the scalar-diquark-scalar-diquark-antiquark type and axialvector-diquark-axialvector-diquark-antiquark type charmed pentaquark states suscu with J^(p)=1/2^(-) can be possible candidates of the excited states observed in the LHCb collaboration.

P-wave Ω_(b) states:masses and pole residues

In this study,we consider all P-wave Ω_(b) states represented by interpolating currents with a derivative and calculate the corresponding masses and pole residues using the QCD sum rule method.Because of the large uncertainties in our calculation compared with the small difference in the masses of the excited Ω_(b) states observed by the LHCb collaboration,it is necessary to study other properties of the P-wave Ω_(b) states represented by the interpolating currents investigated in the present work to gain a better understanding of the four excited Ω_(b) states observed by the LHCb collaboration.

Analysis of the 1S and 2S states of Λ_(Q) and Ξ_(Q) with QCD sum rules

In this article,we study the ground states and the first radial excited states of the flavor antitriplet heavy baryon states ∧Q and ΞQ with the spin-parity JP=1/2+ by carrying out operator product expansion up to vacuum condensates of dimension 10 in a consistent way.We observe for the first time that the higher dimensional vacuum condensates play an important role,and obtain very stable QCD sum rules with variations of the Borel parameters for the heavy baryon states.The predicted masses 6.08±0.09 GeV,2.78±0.08 GeV,and 2.96±0.09 GeV for the first radial excited states ∧b(2 S),∧c(2 S),and Ξc(2 S),respectively,are in excellent agreement with the experimental data and support assigning ∧b(6072),∧c(2765),and Ξc(2980/2970) to be the first radial excited states of ∧b,∧c,and Ξc,respectively.The predicted mass 6.24±0.07 GeV for Ξb(2 S) can be confirmed using experimental data in the future.

A novel method to test particle ordering and final state alignment in helicity formalism

In this study,the non-trival effect of the selection of reference particles for decay angle definitions is demonstrated when constructing the partial-wave amplitude of multi-body decays using helicity formalism.This issue is often ignored in the standard use case of helicity formalism.A new technique is proposed to test the selection of the particle ordering,and it can also be used as a generalized method to calculate the rotation operators that are used for the final-state alignment between different decay chains.Moreover,numerical validations are performed to support the arguments and to verify the effectiveness of the proposed technique.

Possible hidden-charm molecular baryons composed of an anti-charmed meson and a charmed baryon

Using the one-boson-exchange model,we studied the possible existence of very loosely bound hidden-charm molecular baryons composed of an anti-charmed meson and a charmed baryon.Our numerical results indicate that the Σ c ＊ and Σ c states exist,but that the Λ c and Λ c ＊ molecular states do not.

Discovery potentials of doubly charmed baryons

The existence of doubly heavy flavor baryons has not been well established experimentally so far. In this Letter we systematically investigate the weak decays of the doubly charmed baryons, Ξ;and Ξ;, which should be helpful for experimental searches for these particles. The long-distance contributions are first studied in the doubly heavy baryon decays, and found to be significantly enhanced. Comparing all the processes, Ξ;→Λ;K;π;π;andΞ;π;are the most favorable decay modes for experiments to search for doubly heavy baryons.

Spectrum and Bethe-Salpeter amplitudes of ? baryons from lattice QCD

The Ω baryons with JP= 3/2^±, 1/2^± are studied on the lattice in the quenched approximation. Their mass levels are ordered as M3/2＋〈 M3/2- 0≈M1/2-〈 M1/2＋, as is expected from the constituent quark model. The mass values are also close to those of the four Ωstates observed in experiments. We calculate the Bethe-Salpeter amplitudes of Ω（3/2^＋） and Ω（1/2^＋） and find there is a radial node for the Ω（1/2＋） Bethe-Salpeter amplitude, which may imply that Ω（1/2＋） is an orbital excitation of Ω baryons as a member of the（D, LN^P） =（70, 02^＋） supermultiplet in the SU（6）×O（3） quark model description. Our results are helpful for identifying the quantum numbers of experimentally observed Ω states.