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.
We investigate production and decay of the $Λ_c^+ $ hyperon. The production considered is through the $e^+e^-$ annihilation channel, $e^+e^-\rightarrowΛ_c^+ \barΛ_c^-$, with summation over the $\barΛ_c^- $ anti-hyperon spin directions. It is in this situation that the $Λ_c^+ $ decay chain is identified. Two kinds of sequential decays are studied. The first one is the doubly weak decay $B_1\rightarrow B_2 M_2$, followed by $B_2 \rightarrow B_3 M_3$. The other one is the mixed weak-electromagnetic decay $B_1\rightarrow B_2 M_2$, followed by $B_2 \rightarrow B_3 γ$. In both schemes $B$ denotes ba…
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…
We study the electromagnetic form factors of $Λ$ hyperon in the timelike region using the recent experimental data in the exclusive production of $\barΛ Λ$ pair in electron-position annihilation. We present a pQCD inspired parametrization of $G_E(s)$ and $G_M(s)$ with only two parameters, and we consider a suppression mechanism of the electric form factor $G_E(s)$ compared to the magnetic form factor $G_M(s)$. The parameters are determined through fitting our parametrization to the effective form factor data in the reaction $e^+e^-\rightarrow \barΛΛ$. Except the threshold region, our parametri…
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.
Entanglement redistribution of hyperon-antihyperon pair via sequential decay
Nankai University（南开大学）；Institute of Modern Physics, Chinese Academy of Sciences（中国科学院近代物理研究所）；University of Chinese Academy of Sciences（中国科学院大学）；Department of Physics, Hebei University（河北大学物理学院）
We apply a modified vector meson dominance (VMD) model to analyze the electromagnetic form factors of the $Λ_c$ hyperon in the time-like reaction $e^+e^-\rightarrow Λ_c^+ \barΛ_c^-$. In the model, we include the contributions from the vector charmed mesons and their excitations $ψ(1S)$, $ψ(2S)$, $ψ(3770)$, $ψ(4040)$, $ψ(4160)$ and $ψ(4415)$. We perform a combined fit to the available data on the Born cross section in reaction $e^+e^-\rightarrow Λ_c^+ \barΛ_c^-$ and the ratio of the electromagnetic form factors $|G_E/G_M|$ to obtain the values of the model parameters. Our results show that the …
The semileptonic decays and two-body nonleptonic decays of light baryon octet ($T_8$) and decuplet ($T_{10}$) consisting of light $u,d,s$ quarks are studied with the SU(3) flavor symmetry in this work. We obtain the amplitude relations between different decay modes by the SU(3) irreducible representation approach, and then predict relevant branching ratios by present experimental data within $1 σ$ error. We find that the predictions for all branching ratios except $\mathcal{B}(Ξ\rightarrow Λ^0π)$ and $\mathcal{B}(Ξ^*\rightarrow Ξπ)$ are in good agreement with present experimental data, that im…
We present results for the hyperon vector form factor f_1 for $Ξ^0 \rightarrow Σ^+ l\barν$ and $Σ^- \rightarrow n l\barν$ semileptonic decays from dynamical lattice QCD with domain-wall quarks. Simulations are performed on the 2+1 flavor gauge configurations generated by the RBC and UKQCD Collaborations with a lattice cutoff of 1/a = 1.7 GeV. Our preliminary results, which are calculated at the lightest sea quark mass (pion mass down to approximately 330 MeV), show that a sign of the second-order correction of SU(3) breaking on hyperon vector coupling f_1(0) is likely negative.
We determine the hyperon vector couplings $f_1(0)$ for $Σ^{-}\rightarrow nl^-\bar{ν_l}$ and $Ξ^0\rightarrowΣ^{+}l^-\bar{ν_l}$ semileptonic decays in the continuum limit with (2+1)-flavors of dynamical domain-wall fermions, using the Iwasaki gauge action at two different lattice spacings of $a$=0.114(2) and 0.086(2) fm. A theoretical estimation of flavor SU(3)-breaking effect on the vector coupling is required to extract $V_{us}$ from the experimental rate of hyperon beta decays. We obtain the vector couplings $f_1(0)$ for $Σ\rightarrow N$ and $Ξ\rightarrow Σ$ beta-decays with an accuracy of le…
Weak Radiative Hyperon Decays in Chiral Perturbation Theory
利用手征微扰理论研究了弱辐射超子衰变的宇称守恒$a$和宇称破坏$b$振幅。使用么正性计算$a$和$b$的虚部。计算得到了$b$的实部由单圈红外发散图支配。$a$的实部具有很大的理论不确定性，不能可靠地计算。使用$CPS$对称性对$a$和$b$振幅的对应项进行分类。衰变宽度和不对称性的实验值与理论一致，除了$Σ^+ \rightarrow p γ$衰变的不对称性参数。
A combined study of the reactions $K^-p\rightarrow Σ^0π^0$, $Λπ^0$ and $\bar{K}^0n$ at low energies is carried out with a chiral quark-model approach. Good descriptions of the experimental observations are obtained. The roles of the low-lying strangeness $S=-1$ hyperon resonances in these processes are carefully analyzed. We find that: (i) In the $K^-p\rightarrow Σ^0π^0$ process, both $Λ(1405)S_{01}$ and $Λ(1520)D_{03}$ play dominant roles. Significant contributions of $Λ(1670)S_{01}$ and $Λ(1690)D_{03}$ could be seen around their threshold; (ii) In the $K^-p\rightarrow Λπ^0$ process, some obv…
We perform an analysis on the electromagnetic form factors of the $Λ$ hyperon in the time-like reaction $e^+e^-\rightarrow Λ\barΛ$ by using a modified vector meson dominance model. We consider both the intrinsic structure components and the meson clouds components. For the latter one, we not only include the contributions from the $ϕ$ and $ω$ mesons, but also take into account the contributions from the resonance states $ω(1420)$, $ω(1650)$, $ϕ(1680)$ and $ϕ(2170)$. We extract the model parameters by combined fit to the time-like effective form factor $|G_{\rm{eff}}|$, the electromagnetic form…
We study the medium modifications of the spectral functions as well as production cross-sections of the strange vector mesons ($ϕ$, $K^*$ and $\bar {K^*}$) in isospin asymmetric strange hadronic matter. These are obtained from the in-medium masses of the open strange mesons and the decay widths $ϕ\rightarrow K\bar K$, $K^* \rightarrow Kπ$ and $\bar {K^*} \rightarrow {\bar K}π$ in the hadronic medium. The decay widths are computed using a field theoretic model of composite hadrons with quark/antiquark constituents, from the matrix element of the light quark-antiquark pair creation term of the f…
We perform a helicity amplitude analysis for the processes of $e^+e^-$$\rightarrow$$J/ψ,ψ(2S)\rightarrowΞ(1530)\barΞ(1530)\rightarrowππΞ\barΞ\rightarrowΛ\bar\Lambda4π\rightarrow p\bar{p}6π$. The joint angular distribution for these processes are obtained, which allows a proper estimation of the detection efficiency using helicity amplitude information. In addition, the sensitivities of measurement of hyperon asymmetry decay parameters for these processes are discussed.
Motivated by the recent experimental measurements of differential cross sections of the $Σ^{-}p$ elastic scattering in the momentum range of $470$ to $850$ MeV$/c$ by the J-PARC E$40$ experiment, we extend our previous studies of $S=-1$ hyperon-nucleon interactions to relatively higher energies up to $900$ MeV$/c$ for both the coupled-channel $Λp\rightarrow(Λp, Σ^{+}n, Σ^{0}p)$, $Σ^{-}p\rightarrow(Λn, Σ^{0}n, Σ^{-}p)$ and single-channel $Σ^{+}p\rightarrowΣ^{+}p$ reactions. We show that although the leading order covariant chiral effective field theory is only constrained by the low energy data…
We study the meson-baryon interaction in S-wave in the strangeness S=-1 sector using a chiral unitary approach based on a next-to-leading order chiral SU(3) Lagrangian. We fit our model to the large set of experimental data in different two-body channels. We pay particular attention to the $\bar{K} N \rightarrow K Ξ$ reaction, where the effect of the next-to-leading order terms in the Lagrangian are sufficiently large to be observed, since at tree level the cross section of this reaction is zero. For these channels we improve our approach by phenomenologically taking into account effects of th…
By using resonance model, we investigate $K^+ N \rightarrow K N η$ reactions with the assumption that these reactions are dominated by the excitation of $N^*(1535)$ near threshold. It is found that the hyperon and $ρ$ exchange diagrams give the most important contributions to these reactions. Thus these reactions may be a good place to study the coupling of $N^*(1535)$ with $KΛ$, $KΣ$ and $Nρ$ channels. We demonstrate that the angular distributions of final particles provide useful information about the different mechanisms of the $N^*(1535)$ excitations, which could be useful for future exper…
Spin correlation of hyperon-antihyperon systems in $e^+e^-$ annihilation
University of Science and Technology of China（中国科学技术大学）；Anhui Center for fundamental sciences in theoretical physics（安徽基础科学前沿中心）；State Key Laboratory of Particle Detection and Electronics（粒子探测与电子学国家重点实验室）；School of Mechanics and Physics, Anhui University of Science and Technology（安徽理工大学力学与光电学院）
The meson-baryon interaction in s-wave in the strangeness S=-1 sector has been studied, employing a chiral SU(3) Lagrangian up to next-to-leading order (NLO) and implementing unitarization in coupled channels. The parameters of the Lagrangian have been fitted to a large set of experimental data in different two-body channels, paying special attention to the $\bar{K} N \rightarrow K Ξ$ reaction, which is particularly sensitive to the NLO terms. With the aim of improving the model in the $KΞ$ production channels, effects of the high spin hyperon resonances $Σ(2030)$ and $Σ(2250)$ have been taken…
Phenomenological Study of $Ω_c\rightarrow Ω^-π^+$ at Polarized Electron-Positron Collider
Key Laboratory of Nuclear Physics and Ion-beam Application (MOE) and Institute of Modern Physics, Fudan University（核物理与离子束应用教育部重点实验室和现代物理研究所，复旦大学）；College of Physics, Jilin University（吉林大学物理学院）；Institute of High Energy Physics（高能物理研究所）
Comment on "Controlling the dynamical evolution of quantum coherence and quantum correlations in $e^{+} e^{-} \rightarrow Λ\barΛ$ processes at BESIII''
School of Particles and Accelerators, Institute for Research in Fundamental Sciences (IPM)（粒子与加速器学院，基础科学研究所（IPM））
Sequential decays of the triple strange process $\bar{p} p \rightarrow \barΩ^{+} Ω^{-} \rightarrow K^{+} \barΛ K^{-} Λ\rightarrow K^{+} \bar{p} π^{+} K^{-} p π^{-}$: a model-independent approach
本文开发了一种模型无关的不可约张量形式论，用于分析 PANDA 实验中 $\ar{p}p$ 碰撞产生 $\arΩΩ$ 及其三奇异衰变过程，给出了密度矩阵与 Fano 统计张量表达式，并推导了初始与最终系统产生截面之间的关系。
We investigate the joint $Λ\barΛ$ decay in the reaction $e^+ e^- \rightarrow γΛ(\rightarrow pπ^-) \barΛ(\rightarrow \bar{p}π^+)$. This reaction may provide information on the electromagnetic form factors of the Lambda baryon, in the time-like region. We present a conventional diagram-based calculation where production and decay steps are coherent and summations over final-state proton and anti-proton spins are performed. The resulting cross-section distribution is explictly covariant as it is expressed in scalar products of the four-momentum vectors of the participating particles. We compare t…
We analyze the $τ^-\to(Kπ)^-ν_τ$ decays within an effective field theory description of heavy new physics (NP) modifying the SM left-handed weak charged current and include refined SM input for the participant meson form factors exploiting chiral symmetry, dispersion relations and (lattice) data. We include the leading dimension six operators and work at linear order in the effective couplings. Within this setting we: i) follow the derivation in Phys. Rev. Lett. 120 (2018) no.14, 141803 where it was proved unambiguously that it is impossible to understand the BaBar anomaly in the CP asymmetry …
Comment on "Quantum teleportation, entanglement, LQU and LQFI in $e^{+} e^{-} \rightarrow \mathrm{Y} \overline{\mathrm{Y}}$ processes at BESIII through noisy channels''
School of Particles and Accelerators, Institute for Research in Fundamental Sciences (IPM)（粒子与加速器学院，基础科学研究院）
In this paper, we study the polarization of the $Λ(1405)$ in the $γp \rightarrow K^+ πΣ$ reaction within an effective Lagrangian approach and isobar model. In our model, the $Λ(1405)$ is excited through the t-channel $K/K^*$ exchanges and u-channel hyperon exchange. Compared to previous studies, we also include the contribution from a contact term, which is necessary for our model to interpret the polarization of the $Λ(1405)$. In addition, we also discuss the possibility to verify the proposed two-pole structure of the $Λ(1405)$ using the polarization data. We find that the polarization of th…
In this paper, we study the Cabibbo favored non-leptonic $D^0$ decays into $K^- π^+$ decays. First we show that, within the Standard Model, the corresponding CP asymmetry is strongly suppressed and out of the experimental range even taking into account the large strong phases coming from final state Interactions. We show also that although new physics models with extra sequential generation can enhance the CP asymmetry by few orders of magnitude however the resulting CP asymmetry is still far from experimental range. The most sensitive New Physics Models to this CP asymmetry comes from no-mani…
We have analyzed the singularities of a triangle loop integral in detail and derived a formula for an easy evaluation of the triangle singularity on the physical boundary. It is applied to the $Λ_b \rightarrow J/ψK^{-} p$ process via $Λ^*$-charmonium-proton intermediate states. Although the evaluation of absolute rates is not possible, we identify the $χ_{c1}$ and the $ψ(2S)$ as the relatively most relevant states among all possible charmonia up to the $ψ(2S)$. The $Λ(1890)\, χ_{c1}\, p$ loop is very special as its normal threshold and triangle singularities merge at about 4.45 GeV, generating…
The NA61/SHINE collaboration has recently published high precision data on production of $π^\pm$ and $K^\pm$ mesons, protons, antiprotons and $Λ$ hyperons in ${\rm pp}$ interactions at 20, 31, 40, 80 and 158 GeV/c, and in ${\rm pC}$ interactions at 31 GeV/c. The collaboration also presented experimental data on production of particles - $π^\pm$, $K^\pm$, $p^\pm$, $ρ^0$, $ω$ and $K^{*0}$ in $π^-{\rm C}$ collisions at 158 and 350 GeV/c. The collaboration has compared these data with various Monte Carlo model calculations: UrQMD, EPOS, GiBUU, and others. All of the models have various problems. T…
Full one-loop electroweak-corrections for an $e^-e^+\rightarrow t \bar{t}$ process associated with sequential $t\rightarrow b μν_μ$ decay are discussed. At the one-loop level, the spin-polarization effects of the initial electron and positron beams are included in the total and differential cross sections. A narrow-width approximation is used to treat the top-quark production and decay while including full spin correlations between them. We observed that the radiative corrections due to the weak interaction have a large polarization dependence on both the total and differential cross sections.…
We propose to measure the $HZγ$ and $Hγγ$ anomalous couplings in the process of $e^{+}e^{-}\rightarrow Hγ$ with the sequential decay of $H\to b{\bar b}$. The discovery potential of observing the anomalous couplings are explored in details. Our study shows that the electron-positron collider has a great potential of testing the $HZγ$ and $Hγγ$ couplings. Conservative bounds on the two anomalous couplings are also derived when no new physics signal were detected on top of the SM backgrounds.
Because at the tree level $B_s\rightarrow K^+K^-$ is Cabibbo-triple suppressed, so its branching ratio should be smaller than that of $B_s\to π^+ K^-$. The measurements present a reversed ratio as $R=\mathcal B(B_s\rightarrow π^+K^-)/\mathcal B(B_s\rightarrow K^+ K^-)\sim{4.9/33}$. Therefore, It has been suggested that the transition $B_s\to K^+K^-$ is dominated by the penguin mechanism, which is proportional to $V_{cb}V^*_{cs}$. In this work, we show that an extra contribution from the final state interaction (FSI) to $B_s\to K^+K^-$ via sequential processes $B_s\to D^{(*)}_{(s)} \bar D_s^{(*…
As an important sequential work of the S-wave $B_c^{(*)}$ ($^1S_0(^3S_1)$) meson production at the large hadron electron collider (LHeC), we investigate the production of the P-wave excited $B_c^{**}$ states ($^1P_1$ and $^3P_J$ with $J=0,1,2$) via photoproduction mechanism within the framework of nonrelativistic QCD at the LHeC. Generally, the $e^-+P \to γ+ g \rightarrow B_c^{**} +b+ \bar{c}$ process is considered as the main production mechanism at an electron-proton collider due to the large luminosity of the gluon. However, according to our experience on the S-wave $B_c^{(*)}$ meson produc…
We study non-perturbatively the time evolution of cascade decay for generic fields $π\rightarrow ϕ_1ϕ_2\rightarrow ϕ_2χ_1χ_2$ and obtain the time dependence of amplitudes and populations for the resonant and final states. We analyze in detail the different time scales and the manifestation of unitary time evolution in the dynamics of production and decay of resonant intermediate and final states. The probability of occupation (population) "flows" as a function of time from the initial to the final states. When the decay width of the parent particle $Γ_π$ is much larger than that of the interme…
