We have performed a calculation of the scattering amplitude for the three body system $\bar{K}NN$ assuming $\bar{K}$ scattering against a $NN$ cluster, using the Fixed Center approximation to the Faddeev equations. The $\bar{K}N$ amplitudes, which we take from chiral unitary dynamics, govern the reaction and we find a $\bar{K}NN$ amplitude that peaks around 40 MeV below the $\bar{K}NN$ threshold, with a width in $|T|^2$ of the order of 50 MeV for spin 0 and has another peak around 27 MeV with similar width for spin 1. The results are in line with those obtained using different methods but implementing chiral dynamics. The simplicity of the approach allows one to see the important ingredients responsible for the results. In particular we show the effects from the reduction of the size of the $NN$ cluster due to the interaction with the $\bar{K}$ and those from the explicit considiration of the $ πΣN $ channel in the three body equations.
Integral equations for meson-baryon scattering amplitudes are obtained by utilizing time-ordered perturbation theory for a manifestly Lorentz-invariant formulation of baryon chiral perturbation theory. Effective potentials are defined as sums of two-particle irreducible contributions of time-ordered diagrams and the scattering amplitudes are obtained as solutions of integral equations. Ultraviolet renormalizability is achieved by solving integral equations for the leading order amplitude and including higher order corrections perturbatively. As an application of the developed formalism, pion-n…
$\bar d - \bar u$ asymmetry in the proton in chiral effective theory
在相对论和重子框架下,我们计算了手征有效理论中质子的$\bar d - \bar u$不对称性,包括核子和$Δ$的自由度。除了在$x>0$的分布,我们计算的修正所产生的零动量贡献的π彩虹和气泡图在$x=0$,这在以前的分析中没有考虑到的不对称性。我们发现,经验$x$依赖的$\bar d - \bar u$以及集成的不对称性可以很好地再现的横向动量截止参数。
We study the chiral interactions of the hidden charm $D\bar{D}^*$ system within chiral effective field theory. Chiral Lagrangians are constructed by incorporating the chiral symmetry, heavy quark symmetry as well as proper charge conjugation properties of the heavy mesons. The interacting potentials of the $S$-wave $D\bar{D}^*$ are calculated up to second chiral order at 1-loop level, where complete two-pion exchange interactions are included. We further investigate the behaviors of the potentials in coordinate space, as well as their bound state properties. Our studies indicate that there exi…
We construct an effective hadronic model including single heavy baryons (SHBs) belonging to the $(\mathbf{3},\mathbf{3})$ representation under $\mbox{SU}(3)_L \times \mbox{SU}(3)_R$ symmetry, respecting the chiral symmetry and heavy-qaurk spin-flavor symmetry. When the chiral symmetry is spontaneously broken, the SHBs are divided into the baryons with negative parity of $\bar{\mathbf 3}$ representation under $\mbox{SU}(3)$ flavor symmetry which is the chiral partners to the ones with positive parity of ${\mathbf 6}$ representation. We determine the model parameters from the available experimen…
Chiral Perturbation Theory and the $\bar B \bar B$ Strong Interaction
本文用重介子手征微扰理论计算了重介子(粲介子或底介子)到$O(ε^2)$的赝标势。我们考虑了足球,三角形,盒子,交叉图的贡献与2 $ϕ$交换和接触项的一个循环校正。我们注意到,在通道${\bar B \bar B}^{I=1}$、${\bar B_s \bar B_s}^{I=0}$或${\bar B \bar B_s}^{I=1/2}$的小动量区中,总的2个$ϕ$交换势是吸引的,而在通道${\bar B \bar B}^{I=0}$中是排斥的.我们希望这些势的解析手征结构可以用于从格点量子色动力学模拟中外推重介子相互作用。
The s-wave decay amplitude in the nonleptonic decay of baryons is analyzed within heavy baryon chiral perturbation theory in the large-N_c limit at one-loop order, where N_c is the number of color charges. Loop graphs with octet and decuplet intermediate states are systematically incorporated into the analysis and the effects of the decuplet-octet mass difference are accounted for. There are large-N_c cancellations between different one-loop graphs as a consequence of the large-N_c spin-flavor symmetry of QCD baryons. The predictions of large-N_c baryon chiral perturbation theory are in very g…