Spin-parity States Research Articles

Further study of within a chiral quark model* *Supported by the National Natural Science Foundation of China (12175065, 12005060, 12075288, 11735003, 11961141012). Ju-Jun Xie is also supported by the Youth Innovation Promotion Association CAS

In our previous studies, we analyzed the two-body strong decays of the low-lying Ω baryon states within a chiral quark model. The results showed that the mass, total width, and two body decay could be well reproduced with the spin-parity state classified in the quark model. Stimulated by the new observations of the three-body decay process at Belle, in the present study, we further investigate the three-body strong decay within the chiral quark model. It is found that the has a sizeable decay rate into the three-body final states . When considering as the resonance, the predicted ratio is close to the upper limit measured by the Belle Collaboration in 2019; however, it is too small to be comparable to the recent measurement . In addition, the coupled-channel effects on the bare three-quark state from nearby channels , , and are studied. Our theoretical results show that the coupled-channel effects on are not very large, and the molecular component is no more than . To clarify the nature of resonance, precise measurements on the ratio are needed, and further investigation on the effects of coupled channels is recommended.

Fast high-fidelity parity measurement of spin qubits in quantum dots using modulated pulses

Spin qubits in semiconductor quantum dots are a promising candidate for scalable quantum computation. A key step in quantum error correction with spin qubits is the capability to perform high-fidelity parity measurement much faster than the coherence time and to generate entanglement deterministically. Here we propose a parity measurement scheme for two spin qubits by modulated pulses, using a superconducting resonator as a detector. We show that the distinction between spin-parity states can be achieved with a high fidelity within a short measurement time. The combination of parity measurement and feedback control allows the deterministic preparation of various spin entangled states. In addition, the method can be directly applied to parity measurements and surface codes of multiple spin qubits. These results pave the way for fault-tolerant quantum computation with spin qubits.

Spin polarization in nanojunctions of quantum anomalous Hall insulators

We theoretically investigate spin polarized conductance through nanojunctions made by magnetic domains in a thin films of three dimensional ferromagnetic topological insulator (TI) as a quantum anomalous Hall insulator. Writing of magnetic domains is now feasible in recent experiments. Ferromagnetism induced in such materials can control topological phase of the band structure and as consequence, configuration of the states in each band. By means of band analysis, it is demonstrated that in topologically non-trivial bands with non-zero Chern number, there exists a change in spin dominant states among Brillouin zone while spin polarization of trivial bands shows dominant of one spin type. Indeed, there is an interplay between topological invariant of the band spectrum and contribution of the spin states in conductance. We show that in-plane magnetization or structure inversion asymmetry result in a k-dependent parity configuration of surface states in ultrathin film topological insulator. In the conduction and valence bands, a nearly perfect spin polarized conductance is found in a nanojunction composed of anti-parallel magnetic domains which is mediated by a layer under application of in-plane magnetization or perpendicular applied bias. This spin polarized region is extendable with the magnetization. To the sake of completeness, proposed polarization in conductance was also supported by interpretation based on spin and parity local density of states along the interfaces of magnetic domain walls. Analysis of the spin-parity states sheds light to the quantum transport through magnetically doped TI thin-film’s nanojunctions with different mass terms.

Lorentz invariant quantum concurrence for $$\textit{SU}(2) \otimes \textit{SU}(2)$$ spin–parity states

The quantum concurrence of $SU(2) \otimes SU(2)$ spin-parity states is shown to be invariant under $SO(1,3)$ Lorentz boosts and $O(3)$ rotations when the density matrices are constructed in consonance with the covariant probabilistic distribution of Dirac massive particles. Similar invariance properties are obtained for the quantum purity and for the trace of unipotent density matrix operators. The reported invariance features -- obtained in the scope of the $SU(2) \otimes SU(2)$ corresponding to just one of the inequivalent representations enclosed by the $SL(2,\mathbb{C})\otimes SL(2,\mathbb{C})$ symmetry -- set a more universal and kinematical-independent meaning for the quantum entanglement encoded in systems containing not only information about spin polarization but also the correlated information about intrinsic parity. Such a covariant framework is used for computing the Lorentz invariant spin-parity entanglement of spinorial particles coupled to a magnetic field, through which the extensions to more general Poincar\'e classes of spinor interactions are straightforwardly depicted.

Ξ(1690)− production in the K−p→K+K−Λ reaction process near threshold

We investigate $\Xi(1690)^-$ production from the $K^-p\to K^+K^-\Lambda$ reaction within the effective Lagrangian approach at the tree-level Born approximation. We consider the $s$- and $u$-channel $\Sigma/\Lambda$ ground states and resonances for the $\Xi$-pole contributions, in addition to the $s$-channel $\Lambda$, $u$-channel nucleon pole, and $t$-channel $K^-$-exchange for the $\phi$-pole contributions. The $\Xi$-pole includes $\Xi(1320)$, $\Xi(1535)$, $\Xi(1690)(J^p=1/2^-)$,and $\Xi(1820)(J^p=3/2^-)$. We calculate the Dalitz plot density of $(d^2\sigma/dM_{K^+K^-}dM_{K^-\Lambda}$ at 4.2 GeV$/c$) and the total cross sections for the $K^-p\to K^+K^-\Lambda$ reaction near the threshold. The calculation results are in good agreement with previously acquired experimental data. Using the parameters from the fit, we present the total and differential cross sections for the two-body $K^-p\to K^+\Xi(1690)^-$ reaction near the threshold. In our calculation, a strong enhancement at backward $K^+$ angles is predicted because of the dominant $u$-channel contribution. We also demonstrate that the Dalitz plot analysis for $p_{K^-}=1.915 -- 2.065$ GeV/c enables us to access direct information regarding $\Xi(1690)^-$ production, which can be tested by future $K^-$ beam experiments. The possible spin-parity states of $\Xi(1690)^-$ are briefly discussed as well.

Superdeformed band in the N = Z + 4 nucleus 40Ar : A projected shell model analysis

40Ar is among the few sd -shell nuclei known to exhibit superdeformation. An interesting question is whether the experimentally identified superdeformed rotational band in 40Ar has an axially or triaxially deformed shape. Projected shell model calculations assuming an axially deformed basis are performed up to high spins for this nucleus. Our detailed analysis of the wave functions reveals that the high-spin states are dominated by mixed 0-, 2-, and 4-quasiparticle configurations with different K-components. The calculated electric quadrupole transition probabilities reproduce well the known experimental data and suggest a reduced but still significant collectivity in the high spin region. Due to the mixing of various multi-quasiparticle K-configurations, axial asymmetry emerges in the calculation. Throughout the entire rotational band, the extracted triaxial deformation parameters are small but non-zero. Relations of triaxiality and unnatural spin-parity states of the superdeformed side-band are discussed.

Odd mass nuclei in the mass regions 100 ≤ A ≤ 130 from a vertical perspective within the NpNn scheme

We present here the symmetrical level schemes of odd mass pseudo-mirror nuclei for the first time within NpNn scheme. Pseudo-mirror nuclei having particle-hole symmetry are to reflect similar experimental structures, where the NpNn quantity is an indicator of the pronounced symmetry. In the light of available data, the 125Cs–107Rh, 123Cs–109Rh, 127La–105Tc, 127Ce–105Mo, 123Ba–109Ru and 131Nd–101Zr nuclei have been analyzed in a vertical perspective with in the pseudo-mirror nuclei framework. The analysis of level schemes of the nuclei of interest revealed that almost degenerate quadrupole electric transitions from equal spin-parity states in even–odd and odd–even pseudo-mirror nuclei.

Experimental Tests of the Algebraic Cluster Model

The Algebraic Cluster Model (ACM) of Bijker and Iachello that was proposed already in 2000 has been recently applied to 12C and 16O with much success. We review the current status in 12C with the outstanding observation of the ground state rotational band composed of the spin-parity states of: 0+, 2+, 3-, 4± and 5-. The observation of the 4± parity doublet is a characteristic of (tri-atomic) molecular configuration where the three alpha- particles are arranged in an equilateral triangular configuration of a symmetric spinning top. We discuss future measurement with electron scattering, 12C(e,e’) to test the predicted B(Eλ) of the ACM.

Isomeric 26Al beam production with CRIB

We performed an experiment to measure proton resonant elastic scattering of a mixed 26m,gAl beam with a thick target in inverse kinematics by using CNS RI beam sep-arator, located at RIKEN Nishina Center. It aimed to search for strong proton resonances and determine level properties of low spin-parity states in 27Si. Diagnosis of the 26mAl purity of the beam by annihilation radiation are discussed.

Examining barrier distributions and, in extension, energy derivative of probabilities for surrogate experiments

The energy derivatives of probabilities are functions suited to a best understanding of certain mechanisms. Applied to compound nuclear reactions, they can bring information on fusion barrier distributions as originally introduced [1,2], and also, as presented here, on fission barrier distributions and heights. Extendedly, they permit to access the compound nucleus spin-parity states preferentially populated according to an entrance channel, at a given energy.

Statistics of quantum beats in the time dependence of the neutron scattering

The numerical calculations of the delay time distributions for the neutron scattering have been carried out. The scattering of the short wave packet of neutrons with the broad energy interval 500–800 keV by 58Ni nuclei has been studied. The decay curves and average times of the compound scattering were found as for the forward scattering as for the specific spin-parity states. The time oscillations of the decay curves were identified as quantum beats that were caused by the interference of the excited resonance set. The statistical analysis of the frequency spectra of the decay curves oscillations has been carried out. The behavior of the examined statistical observables turns out to be close to the Poisson law.

Collective-coupling analysis of spectra of mass-7 isobars:He7,Li7,Be7, andB7

A nucleon-nucleus interaction model has been applied to ascertain the underlying character of the negative-parity spectra of four isobars of mass seven, from neutron-- to proton--emitter driplines. With one single nuclear potential defined by a simple coupled-channel model, a multichannel algebraic scattering approach (MCAS) has been used to determine the bound and resonant spectra of the four nuclides, of which ^7He and ^7B are particle unstable. Incorporation of Pauli blocking in the model enables a description of all known spin-parity states of the mass-7 isobars. We have also obtained spectra of similar quality by using a large space no-core shell model. Additionally, we have studied ^7Li and ^7Be using a dicluster model. We have found a dicluster-model potential that can reproduce the lowest four states of the two nuclei, as well as the relevant low-energy elastic scattering cross sections. But, with this model, the rest of the energy spectra cannot be obtained.

Analysis of the π+π−π+π− and π+π0π−π0 final states in quasi-real two-photon collisions at LEP

The reactions γ γ → π + π − π + π − and γ γ → π + π 0 π − π 0 are studied with the L3 detector at LEP in a data sample collected at centre-of-mass energies from 161 GeV to 209 GeV with a total integrated luminosity of 698 pb −1 . A spin-parity-helicity analysis of the ρ 0 ρ 0 and ρ + ρ − systems for two-photon centre-of-mass energies between 1 and 3 GeV shows the dominance of the spin-parity state 2 + with helicity 2. The contribution of 0 + and 0 − spin-parity states is also observed, whereas contributions of 2 − states and of a state with spin-parity 2 + and zero helicity are found to be negligible.

SPIN-PARITY ANALYSIS OF THE f1(1285)π± SYSTEM

Using data which had been taken at E831/FOCUS experiment during the Fermilab fixed target run (1996-1997), we have studied the f1(1285)π± system. The reaction is [Formula: see text] and [Formula: see text]. Using partial wave analysis, we have carried out a study of the spin-parity states of f1(1285)π± system including a search for exotic meson states.

Semileptonic Decays of B Meson into Charmed Higher Resonances in the Heavy Quark Effective Theory

Heavy quark effective theory is applied to semileptonic decays of B mesons into charmed higher resonances D X , where subscript X denotes various spin-parity states of resonances. We calculate the differential decay rates and branching ratios of the decay B → D X lν t . We find that the largest fraction of the semileptonic process B → D X lν t other than D(1869) and D*(2010) is D 2 *(1P state) whose value is 0.11%. It is also estimated that among the unidentified modes in the semileptonic decays of B meson other than D(1896) and D*(2010) the total contribution of exclusive higher resonance modes to the branching ratios is 0.3%. The results are compared to the recent experimental data and the other theoretical analyses

Cross section measurement and spin-parity analysis of the reaction γγ → ωϱ

We present results of an analysis of the reaction γγ→ ωϱ in the two-photon process e +e −→ ϵ +e −2 π +2 π − π 0 in the untagged mode. The cross section is largely compatible with previous determinations; however, we do not confirm the enhancement claimed at 1.9 GeV. All observed ω's are accompanied by ϱ's in the recoiling ππ spectrum. An angular correlation analysis shows that the data is not dominated by a single spin-parity state, thus establishing severe constraints on qq q q models which predict J P = 2 + .

A spin-parity analysis of the φK + system produced in the reaction K +p → φK +p, φ → K +K − at 13 GeV / c

The reaction K +p → φK +p at 13 GeV / c has been studied using the CERN Omega spectrometer. The φK + mass spectrum shows a strong threshold enhancement between 1.5 and 2.0 GeV / c 2. A spin-parity analysis of the φK + system has been performed using a double-moments technique. The 1 + spin-parity state is dominant, peaking in the region 1.6 to 1.7 GeV / c 2. A small but significant signal in the 2 − wave peaks at a mass of 1.8 GeV / c 2 with the characteristics of a resonant state.

Observation of an ωπ0 state of mass 1.25 GeV produced by photons of energy 20–70 GeV

An analysis is presented of the channel γp→π +π −π 0π 0p. Evidence is found for an ωπ 0 enhancement of mass ≈1.25 GeV and width ≈0.3 GeV. The enhancement is a mixed spin-parity state with 1 − dominant.

Dynamics of charm molecules

We calculate in a dynamical model based on coupled channels with charm-anticharm mesons\(D\bar D, D\bar D* and D*\bar D*\) and exchanges of light mesons π, η, ϱ and ω the spectrum of spin-parity states up toJ=2 forC=I=0 andC=2,I=0,1. They are compared with experimentally known hidden charm states.

Partial-wave analysis of the (Kππ) − system in the L-region in K −p → (K −π+π−) p at 10, 14.3 and 16 GeV/ c

A partial-wave analysis of the K − π + π − system has been performed in the L-region of the Kgpg mass (1.5–2.0 GeV) in the reaction K −p → (K − gp + gp −)p. The unnatural spin-parity states 0 −, 1 +, 2 −, 3 + are found to dominate over the natural states 1 −, 2 +, 3 −. The 2 −S(K ∗(1420) gp) shows the characteristics of a threshold enhancement. There are indications for a 2 − resonance (M ⋍ 1.58 GeV, Γ ⋍ 0.11 GeV) in the K ∗(890) π P-wave system. The L-enhancement seen in the total Kππ mass spectrum at ∼1.75 GeV is a superposition of enhancements in several partial waves.