Doubly-charged scalar in four-body decays of neutral flavored mesons

We study the four-body decays of neutral flavored mesons,including■,and■.These processes,which could be induced by a hypothetical doubly-charged scalar particle,do not conserve the lepton number.Assuming,as an example,that the mass of the doubly-charged particle is 1000 Ge V,and using the upper bounds of the couplings,we calculate the branching ratios of different channels.For■,and,it is of the order of 10~(-30),10~(-32)–10~(-29),and 10~(-33)–10~(-28),respectively.Based on the experimental results for the■channels,we also find the upper limit for the quantity■     

基于有限元法的激光等离子体诱导玻璃 损伤特性研究

研究了熔石英玻璃元件在纳秒激光等离子体冲击波作用下的表面和横截面损伤形貌,利用有限元法模拟了冲击波在熔石英玻璃内部的传播规律,并基于冲击波在玻璃内部的应力分布规律分析了损伤形成机理.研究发现:在冲击波作用下,石英玻璃会受到沿波面方向的压应力和沿波面切方向的拉应力,在这两种力的作用下,造成以激光辐照中心的弧状层状断裂和沿径向的断裂;冲击波的反射叠加还会使局部拉应力增大,造成靠近后表面的损伤.有限元法能够直观地分析等离子体冲击波对光学元件的作用,并分析光学元件在等离子体冲击波下的损伤机理.     

Isgur-Wise function in B_c decays to charmonium with the Bethe-Salpeter method

The heavy quark effective theory vastly reduces the weak-decay form factors of hadrons containing one heavy quark. Many works attempt to directly apply this theory to hadrons with multiple heavy quarks. In this paper,we examine this confusing application by the instantaneous Bethe-Salpeter method from a phenomenological perspective, and give the numerical results for Bc decays to charmonium where the final states include 1S, 1P, 2S, and 2P. Our results indicate that the form factors parameterized by a single Isgur-Wise function deviate substantially from the full ones, especially when excited states are involved. The relativistic corrections(1/mQcorrections) require the introduction of more non-perturbative universal functions, similar to the Isgur-Wise function, which are the overlapping integrals of the wave functions with the relative momentum between the quark and antiquark.     

Study of singlet-triplet mixing via semileptonic decays

The singlet-triplet mixing of ¹P₁-3P1 is studied via calculating the branching ratios of semileptonic decay Bs→D_s1lν and B→D₁ lν by means of the instantaneous Bethe-Salpeter method. Special attention is paid to the relativistic corrections, since they are large for the P -wave states. Using the Mandelstam Formalism, we compute the transition form factors not only in the high-energy lepton end-point region but also in the full Q2 region. In addition, the non-perturbative QCD effects are taken care of in the overlapping integral over the relativistic wave functions of the initial and final states.     

Probing a Dissipative Phase Transition with a Trapped Ion through Reservoir Engineering

Dissipation is often considered as a detrimental effect in quantum systems for unitary quantum operations.However, it has been shown that suitable dissipation can be useful resources in both quantum information and quantum simulation. Here, we propose and experimentally simulate a dissipative phase transition(DPT) model using a single trapped ion with an engineered reservoir. We show that the ion’s spatial oscillation mode reaches a steady state after the alternating application of unitary evolu...