We present a study of the reaction $π^-p \to ne^+e^-$ for $\sqrt{s}=1.49\,\textrm{GeV}$, including non-resonant Born terms and contributions of the $N(1440)$, $N(1520)$, $N(1535)$ resonances ($R$), using an effective-Lagrangian model, which we extended by a phenomenological phase factor at the $RNρ$ vertex function. We give predictions for both the differential cross section $dσ/dm$ and the spin density matrix elements of the virtual photon that decays into the lepton pair. In the studied energy range, the cross section is dominated by the Born and $N(1520)$ contributions.
A complete and minimal relativistic Lagrangian is constructed at next-to-leading order for SU(3) chiral perturbation theory in the presence of baryon octet and baryon decuplet states. The Lagrangian has 13 terms for the pure decuplet sector, 6 terms for the transition sector from baryon octet to decuplet and (as already known from the literature) 16 terms for the pure octet sector. The minimal field content of 25 of these terms is meson-baryon four-point interactions. 3 terms give rise to the mass splitting for baryon octet and decuplet states, respectively. 2 terms give rise to overall mass s…
We construct the relativistic chiral Lagrangians with decuplet baryons up to the order $\mathcal{O}(p^4)$ (one loop). For the meson-decuplet-decuplet couplings, there are 1, 13, 55, and 548 terms in the $\mathcal{O}(p^1)$-$\mathcal{O}(p^4)$ order Lagrangians, respectively. For the meson-octet-decuplet Lagrangians, the number of independent terms from $\mathcal{O}(p^1)$ to $\mathcal{O}(p^4)$ are 1, 5, 67, and 611, respectively. For convenience of applications, the $πΔΔ$ and $πNΔ$ chiral Lagrangians are picked out. This new form of $Δ$ Lagrangians is equivalent to the original isovector-isospino…
Effects of the next-to-leading order terms in the chiral SU(3) Lagrangian on the strangeness -1 s-wave meson-baryon interactions
利用次领先阶手征SU（3）拉格朗日量的手征么正性方法研究了奇异S=-1扇区中s波中的介子-重子相互作用。该模型是适合在不同的两体通道的大的实验数据集。特别注意的是$Ξ$超子产生反应，$\bar{K} N \rightarrow K Ξ$，在拉格朗日函数中的次主导阶项的效果起着至关重要的作用，因为这个反应在树水平的截面是零。
The near threshold $π^- p \to ηn$ reaction in an effective Lagrangian approach
在等效拉格朗日方法和等压线模型下研究了近阈值$π^- p \to ηn$反应。考虑$s$ -和$u$ -通道核子极和$N^{*}(1535)$共振的贡献，计算了$π^- p \to ηn$反应在阈附近的总截面和微分截面.我们的理论结果可以很好地再现现有的实验数据。它还表明，虽然质心能量位于从反应阈值到$1.65$ GeV的范围内，$s$通道$N^{*}(1535)$共振起主导作用。核子极的影响很小，但$N^*(1535)$共振和核子极之间的干涉项是显著的。在本计算中，来自$t$通道过程的贡献可以忽略不计。
I discuss the properties of the $Λ_{c}$ baryon in nuclear matter at zero or finite temperature. Starting from the Lagrangian based on the heavy-quark effective theory, I derive the effective Lagrangian for the $Λ_{c}$ baryon existing as an impurity particle. Adopting the one-loop calculation for nucleons, I derive the effective potential as the quantity for measuring the stability of the $Λ_{c}$ baryon in nuclear matter. The parameters in the Lagrangian are fitted to reproduce the scattering length of the nucleon and the $Λ_{c}$ baryon estimated in the lattice QCD simulations and the chiral ex…
Pion production in proton-nucleus (p+A) collisions outside the kinematical boundary of proton-nucleon (p+N) reactions, the so-called cumulative effect, is studied. Restrictions from energy-momentum conservation on the energy of pions emitted in the backward direction in the target rest frame are analyzed. It is assumed that the cumulative pions are produced in p+A reactions by heavy baryonic resonances. The baryonic resonances are first created in p+N reactions. Due to successive collisions with nuclear nucleons the masses of these resonances may then increase and, simultaneously, their longit…
Resonance model study of kaon production in baryon baryon reactions for heavy ion collisions
在相对论树能级处理的共振模型下，研究了重子-重子（$N$和$Δ$）碰撞中总K介子产生截面的能量依赖性.本研究是首次尝试完成一个系统的，一致的调查的基本K介子生产反应的介子重子和重子重子反应。我们的模型表明，$N N \to N Y K$和$ΔN \to N Y K$（$Y = Λ$或$Σ$）反应的同位旋平均总截面的大小几乎是相等的能量高达约200兆电子伏以上的阈值。然而，$ΔN$反应的幅度变得约6倍以上的$N N$反应在能量约1 GeV以上的阈值。此外，$N N \to ΔY K$反应的同位旋平均总截面的大小原来是可比较的$N N \to N Y K$反应在$N N$不变碰撞能量约3.1 GeV，约5至10倍大的$N N$不变碰撞能量约3.5 GeV。对重离子碰撞中K介子产生的输运模型研究所需的所有同位旋通道的微观截面进行了参数化。然后将这些横截面应用于相对论输运模型中，以研究对底层基元K ~+产生横截面的敏感性。
Baryon-to-meson and baryon-to-photon transition distribution amplitudes (TDAs) arise in the collinear factorized description of a class of hard exclusive reactions characterized by the exchange of a non-zero baryon number in the cross channel. These TDAs extend the concepts of generalized parton distributions (GPDs) and baryon distribution amplitudes (DAs). In this review, we discuss the general properties and physical interpretation of baryon-to-meson and baryon-to-photon TDAs. We argue that these non-perturbative objects are a convenient complementary tool to explore the structure of baryons…
The $γp \to n a^+_2(1320) \to n ρ^0 π^+$ reactions within an effective Lagrangian approach
利用有效拉格朗日方法研究了$γp \to n a^+_2(1320)$和$γp \to n ρ^0 π^+$反应中$a_2(1320)$介子光子的产生.对于$γp \to n a^+_2(1320)$反应，通过只考虑$t-$通道$π^+$交换的贡献，我们得到了目前实验总截面数据的一个相当好的描述。我们还研究了对$γp \to n π^+ π^+ π^-$反应起主要作用的$γp \to n ρ^0 π^+$反应。后一种反应是由CLAS协作组织测量的。给出了$γp \to n ρ^0 π^+$反应的总截面、不变质量分布和Dalitz图，为以后的实验提供了检验。
The production of backward nucleons, $N(180^\circ)$, at $180^\circ$ in the nuclear target rest frame in proton-nucleus ($\mathrm{p}+A$) collisions is studied. The backward nucleons appearing outside of the kinematically allowed range of proton-nucleon ($\mathrm{p}+N$) reactions are shown to be due to secondary reactions of heavy baryonic resonances produced inside the nucleus. Baryonic resonances $R$ created in primary $\mathrm{p}+N$ reactions can change their masses and momenta due to successive collisions $R+N\rightarrow R +N $ with other nuclear nucleons. Two distinct mechanisms and kinemat…
The $K^- p \rightarrow ηΛ$ reaction in an effective Lagrangian model
我们报告的理论研究的$K^- p \to ηΛ$反应阈值附近使用有效的拉格朗日方法。考虑了$s-$通道$Λ(1670)$、$t-$通道$K^*$和$u-$通道质子极图的作用。我们表明，总的截面数据是很好地再现。然而，仅考虑$s-$波$Λ(1670)$态以及$t-$和$u-$通道的背景贡献并不足以描述$K^- p \to ηΛ$反应角分布中的碗状结构，这表明在某些能量区域应该存在对该反应有贡献的较高分波.事实上，如果我们考虑来自$D_{03}$共振的贡献，我们可以描述碗结构，然而，需要相当小的宽度（$\sim 2$ MeV）的这种共振。
The covariant operator expansion method used by the Bonn-Gatchina group for the analysis of the meson photoproduction data is extended on the case of meson electro-production reactions. The angular dependence of the partial waves is deduced and the obtained amplitudes are compared with those used in other analyses of the electro-production reactions
Isoscalar-Isovector Interferences in $πN \to N e^+ e^-$ Reactions as a Probe of Baryon Resonance Dynamics
在$ω$阈值附近的排他反应$π^- p \to n e^+ e^-$和$π^+ n \to p e^+ e^-$中的等标度矢量（$ρ-ω$）干扰导致依赖于束能量的双电子不变质量分布的明显差异。这种效应的强度取决于共振与核子矢量-介子通道的耦合以及其他共振性质。因此，这些反应的综合分析可以作为确定重子共振动力学的工具。
A scale-invariant chiral effective Lagrangian is constructed for octet pions and a dilaton figuring as Nambu-Goldstone bosons with vector mesons incorporated as hidden gauge fields. The Lagrangian is built to the next-to-leading order in chiral-scale counting without baryon fields and then to leading order including baryons. The resulting theory is hidden scale-symmetric and local symmetric. We also discuss some possible applications of the present Lagrangian.
In the case of three quark flavors, (pseudo)scalar diquarks transform as antiquarks under chiral transformations. We construct four spin-1/2 baryonic multiplets from left- and right-handed quarks as well as left- and right-handed diquarks. The fact that two of these multiplets transform in a "mirror" way allows for chirally invariant mass terms. We then embed these baryonic multiplets into the Lagrangian of the so-called extended Linear Sigma Model, which features (pseudo)scalar and (axial-)vector mesons, as well as glueballs. Reducing the Lagrangian to the two-flavor case, we obtain four doub…
We study the productions of charmed baryons ${\bar Λ}_c^- Λ_c^+$, ${\bar Λ}_c^- Σ_c^+$, and ${\bar Σ}^- Σ_c^+$ in the antiproton-proton collisions within an effective Lagrangian model that has only the baryon-meson degrees of freedom and involves the physical hadron masses. The baryon production proceeds via the $t$-channel exchanges of $D^0$ and $D^{*0}$ mesons in the initial collision of the antiproton with the target proton. The distortion effects in the initial and final states are accounted for by using an eikonal approximation-based procedure. We find that the reaction amplitudes of all …
We investigate the $\bar{p} p \to ϕϕ$ reaction within an effective Lagrangian approach.We show that the inclusion of either a scalar meson $f_0$ or a tensor meson $f_2$ in the $s$-channel can lead to a fairly good description of the bump structure of the total cross section around the invariant $\bar{p} p$ mass $W \simeq 2.2$ GeV, which cannot be reproduced with only the "background" contributions from $t$- and $u$-channel $N^*(1535)$ resonance as studied in a previous work. From the fits, we infer the properties of the involved scalar or tensor resonances.
Radiative and non radiative muon capture on the proton in heavy baryon chiral perturbation theory
在重子手征微扰理论（HBChPT）的背景下，利用Ecker和Mojzis（E&M）的新的O（p^3）拉格朗日量，计算了μ介子被质子捕获到O（p^3）的振幅。我们获得的标准μ子捕获形状因子的表达式，并确定三个系数的E&M拉格朗日，即b_7，b_{19}，和b_{23}。我们描述了下一步的进展，一个辐射μ子捕获过程的计算，μ + p --> n + nu + gamma。
We study three-flavor octet baryons by using the so-called extended Linear Sigma Model (eLSM). Within a quark-diquark picture, the requirement of a mirror assignment naturally leads to the consideration of four spin-$\frac{1}{2}$ baryon multiplets. A reduction of the Lagrangian to the two-flavor case leaves four doublets of nucleonic states which mix to form the experimentally observed states $N(939)$, $N(1440)$, $N(1535)$ and $N(1650)$. We determine the parameters of the nucleonic part of the Lagrangian from a fit to masses and decay properties of the aforementioned states. By tracing their m…
On polarization of strange baryons in reactions p + p -> p + Lambda^0 + K^+ and p + p -> p + Sigma^0 + K^+ near thresholds
分析了pp反应中产生的p + p -> p + Lambda^0 + K^+和p + p -> p + Sigma^0 + K^$的奇异重子在末态（p Lambda^0 K^+）和（p Sigma^0 K^+）阈值附近的极化特性与碰撞质子极化的关系。pp反应的截面是在有效拉格朗日方法内计算的，该方法考虑了碰撞质子初始状态中的强pp再散射，其中一π交换和子强子的强终态相互作用的贡献占主导地位（Eur. J. A 9，425（2000））。
Recent results on the study of light-quark baryons with the ANL-Osaka dynamical coupled-channels (DCC) approach are presented, which contain the N* and Delta* spectroscopy via the analysis of pi N and gamma N reactions and the Lambda* and Sigma* spectroscopy via the analysis of K- p reactions. A recent application of our DCC approach to neutrino-nucleon reactions in the resonance region is also presented.
