Asymmetry parameters in single ionization of He,Ne by XUV pulses

Fully differential cross-sections of single ionization of He and Ne atoms are studied by linearly polarized extreme ultraviolet(XUV)photons in the energy range of 22.1 e V–43.7 e V,using a reaction microscope.Photoelectron angular distributions and theβasymmetry parameters for He 1s^(2) electrons prove the reliability of our experiment,and the β asymmetry parameters extracted from the angular distributions of Ne 2p^(6) electrons are obtained.By comparing with different theoretical calculations,it is found that the contribution of the electron correlation effect in Ne 2p^(6) single ionization becomes increasingly important as the incident photon energy increases,while the relativistic effect is relatively low in the whole incident energy range.Our experimentalβasymmetry parameters may serve as a significant reference to test the most elaborated theories in the field.The datasets presented in this paper,including the photoelectron angular distributions andβasymmetry parameters,are openly available at https://doi.org/10.57760/sciencedb.j00113.00073.

A feedback-controlled Brownian ratchet operated by a temperature switch

In this paper, we present a model of the Brownian motor in a feedback controlled ratchet, in which the application of the flashing potential depends on the state of the particle to be controlled. We derive an analytical expression for the velocity induced by the feedback ratchet, which is a function of several parameters, including the ratio of the two switching temperatures and the asymmetry parameter of the potential field. The motor shows a current inversion when either parameter is varied.

Proton radioactivity half-lives with nuclear asymmetry factor

The dependence of proton emission half-lives on the nuclear asymmetry parameter is investigated using the WKB method and two types of empirical formula.Using the single-folding formalism with asymmetry-depend-ent nuclear radius and surface diffuseness of nuclear matter,the nuclear potential and consequently the half-life are functions of the asymmetry factor.Despite small values of asymmetry in neutron-deficient proton emitters,notice-able changes in the half-lives are observed.The addition of an asymmetry parameter term to the two forms of empir-ical formulas leads to a reduction in the rms error for ground state and isomeric transitions.A noticeable reduction of about 43%is obtained for isomeric transitions in the second form of the empirical formula.Considering ground state transitions in two categories,odd-even and odd-odd emitters,and adopting deformation and asymmetry-dependent empirical formulas,the rms decreases remarkably.The low est values of rms errors,viz.0.1492,0.2312,and 0.1999,are obtained for the aforementioned empirical formulas for ground state transitions of odd-even and odd-odd emit-ters and for all isomeric transitions,respectively.

Phenomenological study of J/ψ→Ξ^(0)(Λπ^(0))ˉΞ^(0)(Λγ)decays

The measurement of decay parameters is one of the important goals of particle physics experiments,and the measurement serves as a probe to search for evidence of CP violation in baryonic decays.The experimental results will aid in advancing existing theoretical research and establishing new experimental objectives.In this study,we formulate the asymmetric parameters that characterize parity violation,and then derive formulas for the measurement of CP violation.The formulae for the joint angular distribution of the full decay chain as well as the polarization observable of Ξ^(0),Ξ¯^(0),Λ,and Λ¯are also provided for experiments.Lastly,we evaluated the sensitivity of two asymmetric parameters:αΞ0→Λπ0(abbreviated asαΞ0)andαΞ¯0→Λ¯γ(abbreviated asαΞ¯0)for future experimental measurements.

Study of parity violation inΛ^(+)_(c)→ΦρandΛ^(+)_(c)→ωρdecays

CP violation in baryonic decays has not been significantly observed.With large data events accumulated at e+e-colliders or the Large Hadron Collider,charmed baryon decays would provide a promising laboratory to test CP symmetry.In this study,we formulateΛ^(+)_(c)→ΦρandΛ^(+)_(c)→ωρdecays for the measurement of their asymmetry parameters in weak decays at the BESII or LHCb experiments.The polarization transfer is analyzed in the two processes of e+e-→Λ^(+)_(c)Λ^(-)_(c)andΛ^(o)_(b)→Λ^(+)_(c)π^(-),and the formulas for the joint angular distribution of these processes are provided.The sensitivity of the measurement of the asymmetry parameters of the above two decay processes is estimated for future experiments.

Λ_(c)^(+)→Λh^(+)和Λc+→∑^(0)h^(+)(h=K,π)衰变道CP破坏的寻找和其分支比与衰变不对称参数的测量

本文报告了粲重子Λ_(c)^(+)的四个弱衰变道Λ_(c)^(+)→Λh^(+)和Λ_(c)^(+)→∑^(0)h^(+)(h=K,π)的系列研究.基于在KEKB能量不对称的正负电子对撞机上的Belle探测器收集的980 fb-1数据样本,作者测量了粲重子两体单卡比玻压低(SCS)衰变过程中的直接电荷共轭-宇称(CP)不对称:ACPdir(Λ_(c)^(+)→ΛK^(+))=+0.021±0.026±0.001和ACPdir(Λ_(c)^(+)→∑^(0)K^(+))=+0.025±0.054±0.004;精确测量了衰变不对称参数(α)和其引起的CP不对称度:AC^(α)_(P)(Λ_(c)^(+)→ΛK^(+))=-0.023±0.086±0.071和AC^(α)_(P)(Λ_(c)^(+)→∑^(0)K^(+))=+0.08±0.035±0.14.这是粲重子SCS衰变的第一个AC^(α)_(P)结果;其次,作者在实验上利用粲重子衰变来寻找超子CP破坏,即利用Λ_(c)^(+)→(Λ,∑^(0))π^(+)衰变获得AC^(α)_(P)(Λ→pπ-)=+0.013±0.007±0.011.以上测量均未发现重子CP破坏的证据.此外,该文还报告了Λ_(c)^(+)两个SCS衰变道的分支比测量:B(Λ_(c)^(+)-ΛK^(+))=(6.57±0.17±0.11±0.35)×10^(-4)和B(Λ_(c)^(+)→∑^(0)K^(+))=(3.58±0.19±0.06±0.19)×10^(-4),这些均为目前最精确的结果.

Polarization in ■ decays

Measurements of decay asymmetry parameters of charmed baryons,e.g.,Ξ0c,provide more data to test the W-emission and W-exchange mechanisms controlled by strong and weak interactions.Taking advantage of the spin polarization in charmed baryon decays,we investigate the possibility to measure weak decay asymmetry parameters in the e^+e^-→Ξ0cΞ0c process.We analyze the transverse polarization spontaneously produced in this process and the spin transfer in the subsequent Ξc decays.The sensitivity to measure the asymmetry parameters is estimated for the decay Ξc→Ξ0π.