In this work we report the calculation of the total cross section for pion-production by the dispersion of neutrinos on nucleons. We use a consistent formalism for the intermediate resonance states of spin $3/2$ , taking care on the conditions imposed by the invariance on contact transformations and using the Sachs parametrization for the form factors. In addition, we incorporate states in the second resonance region up to 1.6 GeV and implement different approaches for all the dressed resonance propagators. In addition to the $Δ$(1232), we include the N$^*$(1440),N$^*$(1535)and N$^*$(1520) resonance contributions, and it is shown that this inclusion improve the description of the total cross section regards a model where only the $Δ$(1230) resonance is considered. Also results for antineutrinos are properly described.
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…
In this article, we study the coherent pion production in neutrino-nucleus interaction in the resonance region using the formalism based on partially conserved axial current (PCAC) theorem which relates the neutrino-nucleus cross section to the pion-nucleus elastic cross section. The pion nucleus elastic cross section is calculated using the Glauber model in terms of pion-nucleon cross sections obtained by parameterizing the experimental data. We calculate the differential and integrated cross sections for charged current coherent pion production in neutrino carbon scattering. The results of i…
我们用pQCD双胶子（2g）交换贡献模拟了大角度中能π-π散射，并讨论了Glauber-Gribov-Landshoff（GGL）分量占优势的开始. pQCD 2g交换贡献在$|t|\sim$ 1 GeV^{2}时就已经很大了，但由于多重软再散射效应的竞争，pQCD交换优势被推迟到$|t|\sim$ 3 GeV^{2}。基于NN和$πN$的总截面数据和Regge因子分解，我们评估了占主导地位的软贡献的$ππ$总截面，并发现与先前推导出的$πN \to X N, X Δ$数据的吸收模型分析的结果一致。
We have calculated coupling constants of a neutral pion with the lowest two nucleon resonances. This includes both the diagonal as well as non-diagonal coupling constants involving a nucleon resonance and a nucleon. For this, we first calculate vacuum-to-pion correlation function of the interpolating fields of two nucleons and then take its matrix elements with respect to a nucleon spinor and/or a nucleon resonance spinor(s). Using different QCD sum rules obtained from different matrix elements we eliminate unwanted coupling constants and solve for the desired ones. This is a simple extension …
Production of pions in proton-nucleus (p+A) reactions outside of a kinematical boundary of proton-nucleon collisions, the so-called cumulative effect, is studied. The kinematical restrictions on pions emitted in backward direction in the target rest frame are analyzed. It is shown that cumulative pion production requires a presence of massive baryonic resonances that are produced during successive collisions of projectile with nuclear nucleons. After each successive collision the mass of created resonance may increase and, simultaneously, its longitudinal velocity decreases. Simulations within…
Vector meson production and nucleon resonance analysis in a coupled-channel approach for energies m_N < sqrt(s) < 2 GeV I: pion-induced results and hadronic parameters
In this article, we present the charged and neutral current coherent pion production in the neutrino-nucleus interaction in the resonance region using the formalism based on the partially conserved axial current (PCAC) theorem which relates the neutrino-nucleus cross section to the pion-nucleus elastic cross section. The pion nucleus elastic cross section is calculated using the Glauber model approach. We calculate the integrated cross sections for neutrino-carbon, neutrino-iron and neutrino-oxygen scattering. The results of integrated cross-section calculations are compared with the measured …
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…
Considering, as a limit case, an approximately flat pion distribution amplitude, which is determined from the hardest, in momentum space, solution of the Bethe-Salpeter equation for the pion wave function, we compute the pion transition form factor $F_{πγγ^{*}}(Q^{2})$ and the pion form factor $F_π(Q^2)$, taking into account the LO as well as NLO form of the hard coefficient function entering the leading-twist factorization formula. We also compute the exclusive photoproduction of pions pairs at high energies, $γγ\to π^{+}π^{-}$, where perturbative QCD can be used to compute the hard scatterin…
Dynamics of the nuclear fragmentations and the charge exchange reactions in pion-nucleus collisions near the $Δ$(1232) resonance energies has been investigated within the Lanzhou quantum molecular dynamics (LQMD) transport model. An isospin, momentum and density-dependent pion-nucleon potential is implemented in the model, which influences the pion dynamics, in particular the kinetic energy spectra, but weakly impacts the fragmentation mechanism. The absorption process in pion-nucleon collisions to form the $Δ$(1232) resonance dominates the heating mechanism of target nucleus. The excitation e…
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。
Effects of pion potential and nuclear symmetry energy on the $π^{-}/π^{+}$ ratio in heavy-ion collisions at beam energies around the pion production threshold
