We consider a pionless effective theory with dibaryon fields for the description of the weak process involving two nucleons. We construct leading order Lagrangians that contain nucleon-dibaryon weak coupling constants. We calculate the physical observable in the photodisintegration of the deuteron at threshold and obtain the result in terms of the nucleon-dibaryon weak coupling constants. Relation to existing calculations is discussed.
We calculate the energy dependence of the asymmetry in the cross sections for circularly polarized photons on an unpolarized deuteron target in $d\vecγ \to np$ in pionless effective field theory. By matching the parity-violating low-energy constants to different sets of corresponding model parameters we obtain estimates for the asymmetry. In addition we calculate two possible figures of merit for the asymmetry in order to assess the preferred photon energy at which to perform a possible future experiment at a high-intensity photon source.
Two parity violating asymmetries from $n p \to d γ$ in pionless effective field theories
我们考虑过程$\vec n p\to d γ$和$ np \to d \overset {\circlearrowleft}γ$的宇称破坏观测量。我们使用无介子有效场论进行计算，有和没有明确的二重子场。在将这些结果与我们已经获得的关于$\vec NN$散射中宇称违反不对称性的结果相结合之后，实验输入原则上允许提取在宇称违反拉格朗日量中出现的所有五个参数。
The symmetries of the Standard Model dictate that for very low energies, where nucleon dynamics can be described in terms of a pionless effective field theory, the leading-order parity-violating nucleon-nucleon Lagrangian contains five independent unknown low-energy constants (LECs). We find that imposing the approximate symmetry of QCD that appears when the number of colors N(c) becomes large reduces the number of independent LECs to two at leading order in the combined pionless effective field theory and large-N(c) expansions. We also find a relation between the two isoscalar LECs in the lar…
We extend from operators with one derivative to operators with three derivatives the analysis of two-body hadronic parity violation in a combined pionless effective field theory (EFT$_{π\!/}$) and large-$N_c$ expansion, where $N_c$ is the number of colors in quantum chromodynamics (QCD). In elastic scattering, these operators contribute to $S$-$P$ and $P$-$D$ wave transitions, with five operators and their accompanying low energy coefficients (LECs) characterizing the $S$-$P$ transitions and six operators and LECs those in $P$-$D$ transitions. We show that the large-$N_c$ analysis separates th…
The parity-violating (PV) nucleon-nucleon ($N\!N$) interaction in the three-nucleon system is investigated using pionless effective field theory ($\mathrm{EFT}(/\!\!\!π)$). This work shows that a next-to-leading order (NLO) PV three-body force is necessary in contradiction with a previous claim [Griesshammer and Schindler in Eur. Phys. J. A 46, 73 (2010)]. Including three-body $P$ to $D$-wave transitions PV three-nucleon observables are calculated to higher energies than previously considered. Using the recent large-$N_{C}$ analysis of the PV $N\!N$ interaction in $\mathrm{EFT}(/\!\!\!π)$ the …
A minimal set of five low energy constants (LECs) for time-reversal and parity violating ($\not{T}\!\!\!\not{P}$) nucleon-nucleon ($N\!N$) interactions at low energies ($E\!<\!m_π^2/M_N$) is given. Using a large-$N_C$ (number of colors in QCD) analysis we show that one linear combination of LECs is $\mathcal{O}(N_C)$, three LECs are $\mathcal{O}(N_C^{0})$, and one linear combination of LECs is $\mathcal{O}(N_C^{-1})$. We also calculate the $\not{T}\!\!\!\not{P}$ observables of neutron spin rotation through a polarized deuteron target and a spin correlation coefficient in nucleon-deuteron scatt…
It is well known that coincidence quasielastic $(\vec{e},e'N)$ reactions are not appropriate to analyze effects linked to parity violation due the presence of the fifth electromagnetic (EM) response $R^{TL'}$. Nevertheless, in this work we develop a fully relativistic approach to be applied to parity-violating (PV) quasielastic $(\vec{e},e'N)$ processes. This is of importance as a preliminary step in the subsequent study of inclusive quasielastic PV $(\vec{e},e')$ reactions. Moreover, our present analysis allows us to disentangle effects associated with the off-shell character of nucleons in n…
Recently at JLab using polarised electron beam on unpolarised deuteron target measurements have been performed for the parity violating asymmetry($A_{PV}$) and there are future plans to measure this asymmetry using various nuclear targets. In this paper, we study $A_{PV}$ in nuclear targets like $^{12}C$, $^{56}Fe$ and $^{208}Pb$, in a local density approximation using spectral function which takes into account Fermi motion, binding energy correction and nucleon correlations. Furthermore, the pion and rho cloud contributions have also been taken into account. The present model has been used ea…
We study parity violation in quasielastic (QE) electron-nucleus scattering using the relativistic impulse approximation. Different fully relativistic approaches have been considered to estimate the effects associated with the final-state interactions. We have computed the parity-violating quasielastic (PVQE) asymmetry and have analyzed its sensitivity to the different ingredients that enter in the description of the reaction mechanism: final-state interactions, nucleon off-shellness effects, current gauge ambiguities. Particular attention has been paid to the description of the weak neutral cu…
How to measure the parity of the $Θ^+$ in $\vec p\vec p$ collisions
由最近的一篇论文引发的托马斯，希克斯和霍洛维茨，我们调查哪些观测值可以用来确定的奇偶性的$Θ^+$从反应$\vec p\vec p \to Σ^+Θ^+$附近的生产阈值。特别是，我们表明，小过剩能量的自旋相关系数$A_{xx}$的符号产生的$Θ^+$的宇称的负值。这个论证完全依赖于泡利原理和宇称守恒，因此是模型无关的。
Hadronic parity violation in $\vec{n} p \to d γ$ with effective field theory
在重子手征微扰理论中，宇称破缺的核子-核子（NN）势一直被考虑到次-次-首阶。我们包括了首阶的一π交换项和次首阶的两π交换项和两核子接触项。通过计算$\vec{n} p \to d γ$中的光子不对称性$A_γ$，采用Siegert定理和精确的宇称守恒NN相互作用唯象势，研究了中间项（双π交换）和短程项（双核子接触）的影响.我们详细探讨了由于控制的贡献的短程相互作用的参数的不确定性。我们得到约20%的不确定性值的$A_γ$的下一个到下一个到领先的顺序。我们讨论了这种不确定性对弱π-核子耦合常数测定的影响以及如何减小这种不确定性。
In the presence of P-violating interactions, the exchange of vector bosons between electrons and nucleons induces parity-nonconserving (PNC) effects in atoms and molecules, while the exchange of vector bosons between nucleons induces anapole moments of nuclei. We perform calculations of such vector-mediated PNC effects in Cs, Ba$^+$, Yb, Tl, Fr and Ra$^+$ using the same relativistic many-body approaches as in earlier calculations of standard-model PNC effects, but with the long-range operator of the weak interaction. We calculate nuclear anapole moments due to vector boson exchange using a sim…
We report a measurement of two energy-weighted gamma cascade angular distributions from polarized slow neutron capture on the ${}^{35}$Cl nucleus, one parity-odd correlation proportional to $\vec{s_{n}} \cdot \vec{k_γ}$ and one parity-even correlation proportional to $\vec{s_{n}} \cdot \vec{k_{n}} \times \vec{k_γ}$. A parity violating asymmetry can appear in this reaction due to the weak nucleon-nucleon (NN) interaction which mixes opposite parity S and P-wave levels in the excited compound $^{36}$Cl nucleus formed upon slow neutron capture. If parity-violating (PV) and parity-conserving (PC) …
Threshold production of the $Θ^+$ in a polarized proton reaction
我们计算横截面$Θ^+$生产阈值附近的极化质子反应，$\vec p \vec p \to Σ^+ Θ^+$，这是最近提出来确定明确的奇偶性$Θ^+$。在理论的不确定性内，对所允许的自旋组态的横截面进行了估计;在s波分量占主导地位的阈值能量区域中，正宇称$Θ^+$的横截面为1微巴恩，负宇称$Θ^+$的横截面为1/10微巴恩。
Spectral functions of the nucleon and its negative parity excited state in nuclear matter are studied using QCD sum rules and the maximum entropy method (MEM). It is found that in-medium modifications of the spectral functions are attributed mainly to density dependencies of the $\langle \bar{q}q \rangle $ and $\langle q^{\dagger}q \rangle $ condensates. The MEM reproduces the lowest-energy peaks of both the positive and negative parity nucleon states at finite density up to $ρ\sim ρ_N$ (normal nuclear matter density). As the density grows, the residue of the nucleon ground state decreases gra…
Time-reversal breaking and parity-conserving millistrong interactions, suggested in 1965, still remain a viable mechanism of CP-violation beyond the Standard Model. One of its possible manifestations is the T-odd asymmetry in the transmission of tensor-polarized deuterons through a vector-polarized hydrogen gas target. Upon the rotation of the deuteron polarization from the vertical direction into the ring plane, the T-odd asymmetries, odd against the reversal of the proton polarization in the target, will continuously oscillate with first or second harmonics of the spin precession frequency. …
Observables of light hadron decays are analyzed in a model of chiral Lagrangian which includes resonance fields of vector mesons. In particular, transition form factors are investigated for Dalitz decays of $V\to Pl^+l^-$ and $P\to γl^+l^-$ $(V=1^-, P=0^-)$. Moreover, the differential decay width of $P\to π^+π^-γ$ and the partial widths of $P\to2γ, V\to Pγ, η^\prime\to Vγ, ϕ(1020)\toω(782)π^0$ and $V\to 3P$ are also calculated. In this study, we consider a model which contains octet and singlet fields as representation of $SU(3)$. As an extension of chiral perturbation theory, we include 1-loo…
We show that local parity violation due to chirality imbalance in relativistic nuclear collisions can be revealed by measuring the projection of the polarization vector onto the momentum, i.e. the helicity, of final state baryons. The proposed method does not require a coupling to the electromagnetic field, like in the Chiral Magnetic Effect. By using linear response theory, we show that, in the presence of a chiral imbalance, the spin 1/2 baryons and anti-baryons receive an additional contribution to the polarization along their momentum and proportional to the axial chemical potential. The a…
We show that the interaction of an axion field, or in general a pseudoscalar field, with the axial-vector current generated by an electron through a derivative-type coupling can give rise to a time-dependent mixing of opposite-parity states in atomic and molecular systems. Likewise, the analogous interaction of an axion field with the axial-vector current generated by a nucleon can give rise to time-dependent mixing of opposite-parity states in nuclear systems. This mixing can induce oscillating electric dipole moments, oscillating parity non-conservation effects and oscillating anapole moment…
