我们发展了一个协变模型的$γ^\ast N \to N(1535)$过渡的类时运动学区域，该区域的平方动量转移$q^2$是积极的。我们的出发点是受类空运动学区域（$Q^2 = -q^2 >0$）数据约束的协变旁观者夸克模型。该模型被用来估计的贡献价夸克的过渡形状因子，并得到一个公平的描述狄拉克形状因子在中型和大型$Q^2$。对于泡利形状因子，有证据表明，除了夸克核的贡献外，介子云效应也有重要的贡献。结合夸克核模型的介子云效应的有效描述，我们推导出一个参数化的类空数据，可以扩展到类时区域的协变。这个扩展使我们能够估计Dalitz衰减宽度的$N(1535)$共振，在其他观测。我们的计算可以帮助解释目前的实验在HADES（$pp$碰撞和其他）。
英文摘要：
We develop a covariant model for the $γ^\ast N \to N(1535)$ transition in the timelike kinematical region, the region where the square momentum transfer $q^2$ is positive. Our starting point is the covariant spectator quark model constrained by data in the spacelike kinematical region ($Q^2 = -q^2 >0$). The model is used to estimate the contributions of valence quarks to the transition form factors, and one obtains a fair description of the Dirac form factor at intermediate and large $Q^2$. For the Pauli form factor there is evidence that beyond the quark-core contributions there are also significant contributions of meson cloud effects. Combining the quark-core model with an effective description of the meson cloud effects, we derive a parametrization of the spacelike data that can be extended covariantly to the timelike region. This extension enabled us to estimate the Dalitz decay widths of the $N(1535)$ resonance, among other observables. Our calculations can help in the interpretation of the present experiments at HADES ($pp$ collisions and others).
In the last years it became possible to measure in HADES the dilepton decays of several baryons. The baryon dilepton decays provide information about the electromagnetic structure of the baryons in the timelike region. In the present work, we study the $B^\prime \to e^+ e^- B$ decays, where $B^\prime$ is a baryon decuplet member and $B$ is a baryon octet member. Our calculations are based on the covariant spectator quark model, where the contribution of the quark core is complemented with an $SU(3)$ contribution from the pion cloud. The pion cloud contribution prove to be relevant in the range…
Dalitz decays of a hyperon resonance to a ground-state hyperon and an electron-positron pair can give access to some information about the composite structure of hyperons. We present expressions for the multi-differential decay rates in terms of general transition form factors for spin-parity combinations J^P = 1/2^+/-, 3/2^+/- of the hyperon resonance. Even if the spin of the initial hyperon resonance is not measured, the self-analyzing weak decay of the "final" ground-state hyperon contains information about the relative phase between combinations of transition form factors. This relative ph…
Dalitz-plot dependence of CP asymmetry in B+- --> K+- K+ K- decays
最近在QCD分解模型框架下预言的B ~+--> K ~+- K ~+ K ~-衰变在K ~+ K ~-不变质量范围内的大CP不对称性已被LHCb合作组证实。我们讨论了这种不对称性的出现和大小，在一个扩展的模型，涉及S-和P-波的D-波f2（1270）共振的贡献，并比较我们的模型与LHCb和BABAR合作的实验数据。
We formulate the final state interaction of the $a_1(1260)$ resonance decay in a manifestly three-body unitary parameterization and fit it to the $a_1(1260)$ lineshape measured by the ALEPH experiment. Dalitz plots calculated from this fit are presented. The work demonstrates the feasibility to numerically solve a previously derived amplitude and its generalization to isobars with spin and coupled channels. The model can also be applied to other meson decays and modified for the finite-volume problem as it arises in lattice QCD due to its manifest unitarity.
Dick Dalitz: Examples of His Contributions to Particle Physics
Dick Dalitz为粒子物理学做出了50年的持久贡献。除了达利茨对、达利茨图和CDD极点，他还在宇称违反、超子共振识别、夸克模型和超核方面做了大量工作。这些主题将被总结，在一定程度上强调了作者与Dalitz在夸克自旋和碎裂相关性方面的合作，特别是在顶夸克及其质量的识别方面的工作。简短的传记信息穿插。这篇论文是基于2006年在国际亚核物理学院的演讲。
Extraction of Meson Resonances from Three-pions Photo-production Reactions
我们研究了从核子上的三π介子光生反应的Dalitz图分析中提取的介子共振性质的模型依赖性。在Phys. Rev. D 84，114019（2011）中开发的酉模型中，我们生成Dalitz图分布作为数据来执行同量异位素模型拟合，这与之前对三π介子产生反应的大多数分析相似。结果表明，两种模型的共振位置吻合较好，但在分叉点附近存在共振极点。从这两个模型中提取的共振振幅的残差和通常的Breit-Wigner程序只对窄宽度的孤立共振一致。对于重叠共振，大多数提取的残留物可能完全不同。我们的研究结果表明，即使有高精度的数据，共振提取应该是基于模型的振幅参数化的三粒子么正性条件的约束。
The scientific heritage of Richard Henry Dalitz, FRS (1925-2006)
Richard H.达利茨于2006年1月13日去世。他已经快81岁了，他的杰出贡献与20世纪粒子和核物理学的一些重大突破密切相关。这些杰出的贡献超越了Dalitz Plot，Dalitz Pair和以他的名字命名的CDD极点。他开创了奇异重子共振、夸克模型中重子光谱和超核的理论研究，并对所有这些都做出了持久的贡献。他对“$θ-τ$之谜”的阐述导致了宇称不是弱相互作用的对称性的发现。本文简要介绍了达利茨对粒子和核物理学的主要贡献，随后是他的科学出版物的第一个全面列表，这些出版物是从几个来源收集的。该列表分为两类：第一，主要部分包括达利茨的研究论文和评论，包括粒子物理学史，传记和回忆录的主题;第二部分列出达利茨撰写的书评，公开演讲和讣告，以及他编辑的书籍。这为在现代物理学中更系统地研究达利茨遗产迈出了必要的第一步。2016年版更新了2006年版，发表在Nucl. Phys. A 771（2006）2-7，doi：10.1016/j.nuclphysa.2006.03.007，and 8-25，doi：10.1016/j.nuclphysa.2006.03.008，首次纳入了Dalitz最近在2004年提交给皇家学会的一份清单中发现的十几种出版物，这些出版物在最初的版本中没有引起我们的注意。
本文在大Nc手征微扰理论和共振手征理论的框架下研究了强子衰变eta' -> eta pi pi的最低阶和次领先阶，共振手征理论在领先1/Nc近似下研究了强子衰变eta' -> eta pi pi.高阶效应，如π-π最终状态的相互作用，考虑到通过一个详细的unitarization程序。有限宽度的影响的情况下，RChT的列入进行了讨论。Dalitz图分布和微分分支比在这两种方法中计算。从不同的治疗获得的预测Dalitz图参数进行比较与最近的测量值。我们发现，eta' -> eta pi pi分支比很容易理解，而Dalitz图参数需要包括pi-pi环，以实现合理的协议。我们的最终预测与实验测量相一致。我们希望我们的结果是相关的，目前和未来的实验分析这些衰变。
The $\textit{BABAR}$ Collaboration data of the $D^0 \to K^0_S K^+ K^-$ process are analyzed within a quasi two-body factorization framework. In earlier studies, assuming $D^0$ transitions to two kaons and the transitions between one kaon and two kaons to proceed through the dominant intermediate resonances, we approximated them as being proportional to the kaon form factors. To obtain good fits, one has to multiply the scalar-kaon form factors, derived from unitary relativistic coupled-channel models or in a dispersion relation approach, by phenomenological energy-dependent functions. The fina…
What is the right formalism to search for resonances?
强子衰变链是QCD谱的主要信息来源之一。我们讨论了在文献中使用的几个分波分析形式主义之间的差异，以建立振幅。我们匹配的螺旋振幅的协变张量基础。因此，我们注意的振幅和运动学和动力学性质的分离奇点的分析性质。我们研究了自旋轨道（LS）形式主义的分析性质，以及一些协变张量方法。特别是，我们明确地建立了B -> psi pi K和B -> Dbar pi pi衰变的振幅，并表明协变方法的能量依赖性是依赖于模型的。我们还表明，通常的递归构造的协变张量明确违反交叉对称性，这将导致不同的共振参数提取的散射和衰变过程。
Relevance of final state interactions in eta'->eta pi pi decays
在这次演讲中，我们对eta '->eta pi pi Dalitz图分布进行了研究。分支比的大小在1/Nc展开的框架内在U（3）手性微扰理论和共振手性理论内被适当地理解。尽管如此，为了实现对达利兹斜率参数的适当描述，必须将π介子环的么正性效应考虑在内。在考虑了末态相互作用后，我们的预测与现有的实验测量结果一致，尽管与以前的理论估计存在一些明显的差异。
A covariant model for the negative parity resonances of the nucleon
我们提出了一个模型的$γ^\ast N \to N^\ast$螺旋振幅，其中$N$是核子和$N^\ast$是一个负宇称核子激发，$SU(6)$ -多重态$[70,1^-]$的成员。该模型结合了单夸克跃迁模型对螺旋度振幅的计算结果和协变旁观夸克模型对$γ^\ast N \to N^\ast(1535)$和$γ^\ast N \to N^\ast(1520)$跃迁的计算结果。在知道了这些跃迁的振幅$A_{1/2}$和$A_{3/2}$后，我们计算了由单夸克跃迁模型定义的三个独立系数，并对与$γ^\ast N \to N^\ast(1650)$、$γ^\ast N \to N^\ast(1700)$、$γ^\ast N \to Δ(1620)$和$γ^\ast N \to Δ(1700)$跃迁相关的螺旋度振幅进行了预测。为了便于与未来的实验数据在高$Q^2$的比较，我们还提供了简单的参数化的振幅，在高$Q^2$与预期的衰减兼容。
In this work, the electromagnetic and gravitational form factors of a spin-$3/2$ particle, $Δ$ resonance, are simultaneously calculated with the help of a relativistic covariant quark-diquark approach. The two kinds of form factors are separately extracted from the matrix elements of the electromagnetic current and of the energy-momentum tensor of the system. Our numerical results show that the approach can well reproduce the electromagnetic monopole, dipole, quadrupole, and octupole form factors comparing to the Lattice calculations. Our obtained electromagnetic moments are also comparable wi…
Pion electro- and photoproduction off the nucleon close to threshold is studied in covariant baryon chiral perturbation theory at O($p^3$) in the extended-on-mass-shell scheme, with the explicit inclusion of the $Δ(1232)$ resonance. The relevant low energy constants are fixed by fitting the available experimental data with the theoretical model. The inclusion of the $Δ$ resonance as an explicit degree of freedom substantially improves the agreement with data and the convergence of the model.
We study radiative charm decays $D \to P_1 P_2 γ$, $P_{1,2}=π,K$ in QCD factorization at leading order and within heavy hadron chiral perturbation theory. Branching ratios including resonance contributions are around $\sim 10^{-3}$ for the Cabibbo-favored modes into $K πγ$ and $\sim 10^{-5}$ for the singly Cabibbo-suppressed modes into $π^+ π^- γ, K^+ K^- γ$, and thus in reach of the flavor factories BES III and Belle II. Dalitz plots and forward-backward asymmetries reveal significant differences between the two QCD frameworks; such observables are therefore ideally suited for a data-driven i…
We study the reaction of pion photoproduction on the nucleon in the framework of chiral perturbation theory with explicit $Δ(1232)$ degrees of freedom. In the covariant approach, we give results up to order $ε^3$ in the small scale expansion scheme. Furthermore, we provide $Δ$-less and $Δ$-full results obtained in the heavy-baryon scheme to analyze the differences to the covariant approach. Low energy constants are fitted to multipole amplitudes using theoretical truncation errors estimated by a Bayesian approach. We also compare our findings to data of neutral pion production cross sections a…
Using the Single Quark Transition Model to predict nucleon resonance amplitudes
我们提出的预测的$γ^\ast N \to N^\ast$螺旋振幅，其中$N^\ast$是一个成员的$[70,1^-]$超多重态。我们将单夸克跃迁模型的结果与协变旁观者夸克模型的结果相结合，得到了螺旋度振幅的结果，其中$γ^\ast N \to N^\ast(1535)$和$γ^\ast N \to N^\ast(1520)$跃迁的结果是一致的。利用协变旁观夸克模型的理论估计，计算了$Q^2$的三个独立函数$A,B$和$C$，其中$Q^2=-q^2$和$q$是动量转移.利用函数$A,B$和$C$的知识，我们估计了跃迁$γ^\ast N \to N^\ast(1650)$、$γ^\ast N \to N^\ast(1700)$、$γ^\ast N \to Δ(1620)$和$γ^\ast N \to Δ(1700)$的螺旋度幅度。分析仅限于与质子靶的反应。跃迁振幅的预测是有效的$Q^2 > 2$ GeV的$^2$。
