Motivated by the recent BESIII measurements of the $J/ψ\to Ξ^0 \barΛK_S^0 + c.c.$ process, we investigate this reaction by considering the contributions from the $Ξ(1690)$, $Λ(1890)$ and $Λ(1830)$ resonances. The $Ξ(1690)$ state is dynamically generated from the $S$-wave pseudoscalar meson-octet baryon interactions within the chiral unitary approach. Our theoretical model provides a good description of the $\barΛK^0$, $Ξ^0 K^0$, and $\barΛΞ^0$ invariant mass distributions. The results indicate that the $Ξ(1690)$ resonance, which was neglected in the experimental analysis by BESIII, plays a crucial role in this process. Furthermore, we evaluate the theoretical uncertainties of our model using the parametric bootstrap method. Future high-precision measurements of this process will further help to elucidate the properties of the $Ξ(1690)$, $Λ(1890)$ and $Λ(1830)$ states.
In this work, we investigate the reaction of $γγ\to D\bar{D}$, taking into account the s-wave $D\bar{D}$ final state interaction. By fitting to the $D\bar{D}$ invariant mass distributions measured by the Belle and BaBar Collaborations, we obtain a good reproduction of the data by means of a $D\bar{D}$ amplitude that produces a bound $D\bar{D}$ state with $I=0$ close to threshold. The error bands of the fits indicate, however, that more precise data on this reaction are needed to be more assertive about the position and width of such state.
We perform a calculation of the strong interaction effects between the $B$ and $D$ mesons in the $\bar{B} \to D \barν \ell$ reaction, as a crossing process of reactions with $BD$ in the final state, where the strong interaction between the mesons leads to a bound $BD$ state. We find corrections to the tree level amplitude of the order of $15-25\%$. We further see the effect of the corrections studied in the $R_D$ ratio for the rates of $\bar{B} \to D \barν_ττ$ and $\bar{B} \to D \barν_e \ell$ decays and find corrections of the order of $10\%$. Given the claims of $1.5\%$ precision in this rati…
We investigate roads for evaluating model-independent cross-section distributions for the sequential hyperon decay $Σ^0\rightarrowΛγ;Λ\rightarrow pπ^- $ and its corresponding antihyperon decay. The hyperons are produced in the reaction $e^+e^-\rightarrow J/ψ\rightarrow Σ^0\barΣ^0$. Cross-section distributions are calculated using the folding technique.
We report on a study of the sequential hyperon decay $Σ^0\rightarrowΛγ;Λ\rightarrow pπ^- $ and its corresponding anti-hyperon decay. We derive a multi-dimentional and model-independent formalism for the case when the hyperons are produced in the reaction $e^+e^-\rightarrowΣ^0\barΣ^0$. Cross-section distributions are calculated using the folding technique. We also study sequential decays of single-tagged hyperons.
Cross-section distributions are calculated for the reaction $e^+ e^- \rightarrow J/ψ\rightarrow \barΛ(\rightarrow \bar{p}π^+) Λ(\rightarrow pπ^-)$, and related annihilation reactions mediated by vector mesons. The hyperon-decay distributions depend on a number of structure functions that are bilinear in the, possibly complex, psionic form factors $G_M^ψ$ and $G_E^ψ$ of the Lambda hyperon. The relative size and relative phase of these form factors can be uniquely determined from the unpolarized joint-decay distributions of the Lambda and anti-Lambda hyperons. Also the decay-asymmetry parameters…
Role of the hidden charm $N^*_{c\bar{c}}(4261)$ resonance in the $π^- p \to J/ψn$ reaction
我们采用一种有效的拉格朗日方法和同量异位素模型来研究$π^- p \to J/ψn$反应中具有隐魅的$N^*_{c\bar{c}}(4261)$共振的作用。通过考虑$N^*_{c\bar{c}}(4261)$和核子极的贡献，预测了该反应的总截面和微分截面。发现总截面的最大值可超过11个$μb$，并且在那里可以看到清晰的$N^*_{c\bar{c}}(4261)$峰，与背景很好地区分开。随着质心能量增加到约4.8 GeV，背景使得后向角的微分截面相当不同。我们的理论结果将为今后的实验中寻找$N^*_{c\bar{c}}(4261)$共振提供有价值的信息。
Production of Hyperons, Charmed Baryons, and Hadronic Molecule Candidates in Neutrino-Proton Reaction
Institute of Theoretical Physics, Chinese Academy of Sciences（中国科学院理论物理研究所）；University of Chinese Academy of Sciences（中国科学院大学）；Tsinghua University（清华大学）；Institute of Modern Physics, Chinese Academy of Sciences（中国科学院近代物理研究所）
Stimulated by the recent LHCb observation of a new exotic charged structure $T^{+}_{cc}$, we propose to use the central diffractive mechanism existing in the $γp\to{}D^{+}\bar{T}^{-}_{cc}Λ_c^{+}$ ($\bar{T}_{cc}$ is antiparticle of $T^{+}_{cc}$) reaction to produce $T^{+}_{cc}$. Our theoretical approach is based on the chiral unitary theory where the $T^{+}_{cc}$ resonance is dynamically generated. With the coupling constant of the $T^{+}_{cc}$ to $DD^{*}$ channel obtained from chiral unitary theory, the total cross sections of the $γp\to{}D^{+}\bar{T}^{-}_{cc}Λ_c^{+}$ reaction are evaluated. O…
We study the $B^+ \to J/ψωK^+ $ reaction, measured by the LHCb collaboration, and show that it is driven by the presence of two resonances, the $X(3940)$ and $X(3930)$, that are of molecular nature and couple most strongly to $D^* \bar{D}^*$, but also to $J/ψω$. Because of that, in the $J/ψω$ mass distribution we find a peak related to the excitation of the resonances and a cusp with large strength at the $D^* \bar{D}^*$ threshold.
Within the framework of the local hidden gauge formalism, we have reanalyzed the hidden-charm vector-vector meson $D^*\bar{D}^*$, $K^*\bar{K}^*$, and $ρρ$ interactions with the quantum numbers $I(J^P)=1(1^+)$. The estimation indicates that $D^*\bar{D}^*$ system could form a bound state around 4010 MeV. By comparing our theoretical estimation with the BESIII measurements of the $e^+e^- \to (D^*\bar{D}^*)^{\pm}π^{\mp}$ and $e^+e^- \to (D^*\bar{D}^*) ^{0}π^{0}$ reactions at $\sqrt{s}=4.26$ GeV , we find that the enhancement structure of the $Z_c(4025)$ in the $D^*\bar{D}^*$ invariant mass distrib…
Next-to-leading order QCD corrections to top quark spin correlations at hadron colliders: the reactions $g g \to t {\bar t} (g)$ and $g q ({\bar q}) \to t {\bar t} q ({\bar q})$
The exclusive reaction $pp \to pp (K^{*0} \bar{K}^{*0} \to K^{+}π^{-}K^{-}π^{+})$ for the LHC experiments is discussed. The amplitudes for the reaction are formulated within the tensor-pomeron approach. We consider two diffractive mechanisms: the $f_{2}(1950)$ $s$-channel exchange mechanism and the $K^{*0}$-exchange mechanism. First mechanism is a candidate for central diffractive production of tensor glueball and the second one is an irreducible continuum. Comparison with data from WA102 experiment are made and predictions for LHC experiments are given. We find that including the continuum co…
We propose two reactions, $\bar{B}^0 \to K^0 D^{+} K^-$ and $\bar{B}^0 \to K^{*0} D^{*+} K^-$, already measured at Belle, to look into the $J^P=0^+$, $X_0(2866)$ state and a $1^+$ partner of molecular $D^*\bar{K}^*$ nature, by looking at the $D^+ K^-$ and $D^{*+} K^-$ invariant mass distributions, respectively. Very clear peaks over the background are predicted and the branching ratios for the production of these states are evaluated to facilitate the task of determining the needed statistics for their observation. The fact that the $K^{*0} K^-$ mass distribution from accumulation of events of…
Role of the hadron molecule Lambda_c(2940) in the p bar(p) -> p D0 bar(Lambda)_c(2286) annihilation reaction
考虑t通道D 0，D*0介子交换和Lambda_c（2286），Lambda_c（2940）重子的共振贡献，研究了p bar（p）→ p D 0 bar（Lambda）_c（2286）的湮灭过程.我们假定Lambda_c（2940）重子是pD*0分子态，自旋宇称为（1/2）+和（1/2）-。结果表明，在p bar（p）-> Lambda_c（2286）bar（Lambda）_c（2286）的阈值附近，中间态Lambda_c（2940）的贡献也很大，并且在PANDA实验中可以观察到。另一个结论是，与选择（1/2）+相比，Lambda_c（2940）的自旋宇称分配（1/2）-给出了截面的增强。
We have performed a calculation of the $D\bar D$, $D\bar D^\ast$, $D^\ast\bar D$, $D^\ast\bar D^\ast$ components in the wave function of the $ψ(3770)$. For this we make use of the $^3P_0$ model to find the coupling of $ψ(3770)$ to these components, that with an elaborate angular momentum algebra can be obtained with only one parameter. Then we use data for the $e^+e^-\to D\bar D$ reaction, from where we determine a form factor needed in the theoretical frame work, as well as other parameters needed to evaluate the meson-meson selfenergy of the $ψ(3770)$. Once this is done we determine the $Z$ …
The $\bar{K} N \rightarrow K Ξ$ reaction in coupled channel chiral models up to next-to-leading order
本文采用基于次领先阶手征SU（3）拉格朗日量的手征么正方法，研究了S波中奇异度S=-1扇区的介子-重子相互作用。我们将我们的模型拟合到不同两体通道中的大量实验数据。我们特别注意的$\bar{K} N \rightarrow K Ξ$反应，在拉格朗日次领先的顺序项的效果是足够大的观察，因为在树的水平，这个反应的截面是零。对于这些通道，我们改进我们的方法，考虑到高自旋超声波共振的影响的现象。
In this work, we make a theoretical study on the $p \bar p \rightarrow Λ\barΛη$ reaction for antiproton beam energy from threshold to 4GeV within an effective Lagrangian approach and isobar model. By assuming this reaction is dominated by the excitation of $Λ$ and $\bar Λ$ resonances in intermediate states, we calculate the total cross sections and give the predictions of the angular distribution and invariant mass spectrum of final particles. In particular, we discuss the possibility to verify the existence of a narrow $Λ$ resonance found in the process of $K^- p\to ηΛ$ in the present reactio…
We study the $J/ψ\to ϕK \bar K$ decay, looking for differences in the production rates of $K^+ K^-$ or $K^0 \bar K^0$ in the region of 1700-1800 MeV, where two resonances appear dynamically generated from the vector-vector interaction. Two resonances are known experimentally in that region, the $f_0(1710)$ and a new resonance reported by the BABAR and BESIII collaborations. The $K \bar K$ should be produced with $I=0$ in that reaction, but due to the different $K^{*0}$ and $K^{*+}$ masses some isospin violation appears. Yet, due to the large width of the $K^*$, the violation obtained is very s…
Helicity amplitudes and crossing relations for antiproton proton reactions
反质子湮灭反应允许在类时区域内唯一地获得核子电磁形状因子的模和相位。我们给出了s通道中不等质量单光子反应$p \bar{p}\to l^+ l^-$的螺旋度振幅，其中包括轻子质量。这些幅度的相对符号使用简单的不变性性质来确定。还给出了湮灭反应$p \bar{p} \to N \bar{N}$的螺旋度振幅，其中$N$是任何具有结构的旋量粒子。讨论了$e p \to e p$散射与$p \bar{p}\to l^+ l^-$湮灭通道之间的交叉关系，给出了螺旋度振幅的交叉矩阵。该矩阵可用于验证由于单光子交换而导致的空间螺旋度振幅的已知表达式。
We have chosen the $\bar{B}^0 \to D^{*+} \bar{D}^{*0} K^-$ reaction in order to observe the $I=0, J^P=1^+$ ($R_1$) partner state of the $X_0(2866)$ stemming from the $D^*\bar{K}^*$ molecular picture. The reaction proceeds via external emission in the most favored Cabibbo decay mode and one observes the $R_1$ state as a very strong peak versus the background in the $D^{*+} K^-$ spectrum. The branching ratio for $R_1$ production in this reaction is estimated of the order of $4\times 10^{-3}$. The method used, applied to the $B^+ \to D^- D^+ K^+$ reaction, produces a ratio of signal to background…
We investigate the charmed baryon production reaction $p\bar{p}\rightarrowΛ_c\barΛ_c$ in an effective Lagrangian approach. Besides the $t$-channel $D^0$ and $D^{*0}$ mesons exchanges, the $s$-channel $Y(4630)$ meson exchange is taken into account. For the total cross sections, the $D^0$ and $D^{*0}$ mesons provide minor background contributions, while the $Y(4630)$ state gives a clear peak structure with the magnitude of 10 $μ$b at center of mass energy 4.63 GeV. Basing on the results, we suggest that the reaction of $p\bar{p}\rightarrowΛ_c\barΛ_c$ can be used to search for the $1^{--}$ charmo…
Partial-wave analysis of $\bar K N$ scattering reactions
我们通过单能分波分析研究了两体反应$\bar K N\rightarrow \bar K N$、$\bar K N\rightarrow πΛ$和$\bar K N\rightarrow πΣ$。能量范围1480 - 2100 MeV。因此，提取的这些反应的分波振幅的多通道能量依赖模型满足的分波$S$矩阵的么正性的约束。我们得到了很好的预测微分截面，极化，极化截面，和截面这些反应从一个全球性的能量依赖的解决方案。
We have analyzed the reaction $χ_{c0}\to \bar{p} K^+Λ$ reported by the BESIII Collaboration, taking into account the contributions from the intermediate $K(1830)$, $N(2300)$, and $Λ(1520)$ resonances. Our results are in good agreement with the BESIII measurements, and it is found that the anomalous enhancement near the $\bar{p}Λ$ threshold is mainly due to the contribution of the $K(1830)$ resonance. We also show that the interference of the high-mass $N^*$ and $Λ^*$ can not produce the anomalous enhancement near the $\bar{p}Λ$ threshold.
Low-energy pion-pion scattering in the $pp \to ppπ^{+}π^{-}$ and $p\bar p \to p\bar pπ^{+}π^{-}$ reactions
我们评估的贡献，π介子再散射的$p p \to p p π^+ π^-$和$p \bar p \to p \bar p π^+ π^-$反应。我们将我们的结果与接近阈值的实验数据进行比较。发现π介子-π介子再散射的贡献可以忽略不计。对未来在达姆施塔特GSI高能储存环（HESR）上使用PANDA探测器的实验进行了预测。讨论了如何切断主导的Roper共振和双$Δ$激发机制，导致最终态的$p p π^+ π^-$通道。给出了动量转移、横向动量、有效双π介子质量、π介子间相对方位角和π介子快度的微分分布。
The near-threshold $e^+e^- \to Λ\barΛ$ reaction is studied with the assumption that the production mechanism is due to a near-$Λ\barΛ$-threshold bound state. The cross section of $e^+e^- \to Λ\barΛ$ reaction is parametrized in terms of the electromagnetic form factors of $Λ$ hyperon, which are obtained with the vector meson dominance model. It is shown that the contribution to the $e^+e^- \to Λ\barΛ$ reaction from a new narrow state with quantum numbers $J^{PC}=1^{--}$ is dominant for energies very close to threshold. The mass of this new state is around 2231 MeV, which is very close to the ma…
We study the $\bar K p \to Y K\bar K π$ reactions with $\bar K = \bar K^0, K^-$ and $Y=Σ^0, Σ^+, Λ$, in the region of $K\bar K π$ invariant masses of $1200-1550$ MeV. The strong coupling of the $f_1(1285)$ resonance to $K^* \bar K$ makes the mechanism based on $K^*$ exchange very efficient to produce this resonance observed in the $K\bar K π$ invariant mass distribution. In addition, in all the reactions one observes an associated peak at $1420$ MeV which comes from the $K^* \bar K$ decay mode of the $f_1(1285)$ when the $K^*$ is placed off shell at higher invariant masses. We claim this to be…
The $Y(4220)$ production in the process of $p\bar{p} \to Y(4220)π^0$ is studied within the effective Lagrangian approach. We first study the $e^+e^-\to Y(4220) \to p\bar{p}π^0$ reaction at center-of-mass energy $4.258$ GeV with the assumption that the $Y(4220)$ is a $ψ(4S)$ state. We show that the inclusion of nucleon and nucleon resonance leads to a quite good description of the experimental data of $π^0 p$ and $π^0 \bar{p}$ invariant mass distributions. Then, the total and angular distributions of the $p\bar{p} \to Y(4220)π^0$ reaction are investigated. It is shown that the nucleon pole is d…
Within the effective Lagrangian approach, we study the $p\bar{p} \rightarrow ψη$ [$ψ\equivψ(3686)$, $J/ψ$] reaction at the low energy where the contributions from nucleon pole and low-lying nucleon resonances, $N(1520)$, $N(1535)$ and $N(1650)$ are considered. All the model parameters are determined with the help of current experimental data on the decay of $ψ\to p \bar{p} η$. Within the model parameters, the total and differential cross sections of the $p\bar{p} \rightarrow ψη$ reaction are predicted. We show that the relative phases between different amplitudes of different nucleon resonance…
The $\bar{K} N \rightarrow K Ξ$ reaction in coupled channel chiral models up to next-to-leading order
本文采用次领先阶的手征SU（3）拉格朗日量，在耦合道中实现么正化，研究了奇异度S=-1扇区中s波中的介子-重子相互作用.拉格朗日的参数已被安装到一个大的实验数据在不同的两体通道，特别注意的$\bar{K} N \rightarrow K Ξ$反应，这是特别敏感的非线性光学条款。为了改进$KΞ$产生通道中的模型，唯象地考虑了高自旋超子共振$Σ(2030)$和$Σ(2250)$的影响.
The reaction $e^+e^-\rightarrow Λ^+_c\barΛ^-_c$ is investigated at energies close to the threshold with emphasis on the role played by the $X(4630)$ resonance. The interaction in the final $Λ^+_c \barΛ^-_c$ system, constructed within chiral effective field theory and supplemented by a pole diagram that represents a bare $X(4630)$ resonance, is taken into account rigorously. The pole parameters of the $X(4630)$ are extracted and found to be compatible with the ones of the $X(4660)$ resonance that have been established in the reaction $e^+e^- \to π^+π^-ψ(2S)$. The actual result for the $X(4630)$…
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。
In this work, we investigate the connection and compatibility between $νn \rightarrow \barν \bar{n}$ reactions and $n$-$\bar{n}$ oscillations based on the $SU(3)_c \times SU(2)_L \times U(1)$ symmetry model with additional Higgs triplets. We explore the possibility that the scattering process $νn\rightarrow \barν\bar{n}$ produced by low-energy solar neutrinos gives rise to an unavoidable background in the measurements of $n$-$\bar{n}$ oscillations. We focus on two different scenarios, depending on whether the $(B-L)$ symmetry could be broken. We analyze the interplay of the various constraints…
Based on the prediction of a $D^*\bar{D}^*$ molecular state $Z_c(4000)$ with isospin $I=1$ in the coupled channel approach, we suggest to search for this state in the reaction $B^- \to J/ψρ^0 K^-$. By taking into account the final state interactions of $J/ψρ$ and $D^{*0}\bar{D}^{*0}$, and the contribution from the $K_1(1270)$ resonance, we find that the $J/ψρ$ mass distribution shows a peak around 4000~MeV, which could be associated to the $D^*\bar{D}^*$ molecular state $Z_c(4000)$. Searching for the $Z_c(4000)$ in the reaction $B^- \to J/ψρ^0 K^-$ is crucial to understand the internal structu…
Model-independent aspects of the reaction $\bar{K} + N \to K + Ξ$
各种模型无关的方面的$\bar{K} N \to K Ξ$反应进行了研究，从最一般的结构与$J^P=\frac12^\pm$和$\frac32^\pm$的$Ξ$重子的反应振幅的测定和可观的，允许一个完整的确定这些振幅。极化观测量由自旋密度矩阵元构成。特别地，利用关于反应平面的反射对称性以模型无关的方式确定所产生的$Ξ$的奇偶性。此外，推广了Biagi $\mathrm{\textit{et al. } [Z. Phys.\ C \textbf{34}, 175 (1987)]}$的工作，提出了一种同时确定$Ξ$重子基态和激发态的自旋和宇称的方法。
