經過兩年經營，雙光子反應中重子生成機制研究所須分析工具已趨完善，結果陸續正式發表。繼先前p p → γγ ，本年度將有Λ Λ → γγ ， 0 0 Σ Σ → γγ ，及部分+ + Σ Σ → γγ 結果，檢驗flavor symmetry 及spin 在強子生成過程中所扮演的角色。在另外一方面，Belle 實驗產生鉅量數據，雙光子反應中重子生成的能量分佈較先前實驗更廣，需要更好理論配合。相信在實驗與理論相互配合下，我們對重子生成機制會有更深一層瞭解。同時進行項目有： 1. S SK K → γγ 分析工作 本年度重心先是S S C2 C0 K K → χ χ → γγ ，量測) γγ → χ χ ( Γ C2 C0 ；下一步為) K K → γγ ( σ S S 測量，此結果與高能量(high W) ) π π → γγ ( σ _ + ， ) K K → γγ ( σ _ + 比較，可驗證pQCD 理論之正確性。 2. Single tag 事件 過去中大探討之雙光子反應均假設為no-tag 事件，實驗上兩者有重疊地方。加上未來線性加速器中ISR(Initial State Radiation)是一項重要因素，與single-tag 相近。最重要的是single-tag 事件的起始狀態（自旋為1）與no-tag（自旋為2 或0）不同。在此狀態下，強子生成機制是否有所不同，值得探討。 3. Bell @ Belle（EPR 實驗） 利用強子生成過程中之相干性，測試Bell 不等式。去年已有初步結果，今年將整理發表，並更深入探討其量子態之相干性。 The necessary tools for baryon productions in two photon collisions have been developed and become mature. Related physics results are now ready for publications. In addition to measurement of cross section p p → γγ previous project, measurements of cross sections of Λ Λ → γγ , 0 0 Σ Σ → γγ and preliminary result on + + Σ Σ → γγ are expected from this proposal. Series measurements on baryon productions in two-photon collisions examine roles of flavor symmetry and spin played during their production process. In the other direction, Belle experiment produce huge amount of data which extends energy distribution of baryons produced in two photon collisions even wider. Such dynamical range needs a more comprehensive theory to cover it. As consequences of the above mentioned experimental and theoretical interplay, deeper and profound understanding of baryon production mechanism is expected. In paralled to baryon productions, there are other related topics will be carried out this year: 1. S SK K → γγ analysis The primary goal is measurement of ) γγ → χ χ ( Γ C2 C0 . The next one is measurement of ) K K → R → γγ ( σ S S , where R』s are f2(1270), f2』(1525), X(1750)….and ) K K → γγ ( σ S S . The later can be compared with ) π π → γγ ( σ _ + , and ) K K → γγ ( σ _ + as a test of pQCD. 2. Single tag events Few issues make single tag events study important: a. The initial quantum state of single tag events (spin = 1) is different from that of no tag event (spin = 0 or 2). It is worth to study production mechanism of hadrons shall be different under different initial quantum states. b. It is an unavoidable background in no tag events. One has to learn how to estimate it. c. It is similar to ISR(Initial State Radiation) process in e+e- collider machine, which is important in future linear collider. The proposal will launch an initial investigation of single tag events. The first stage is to understanding how to trig such events efficiently but without scarifying quality of present trig. 3. Bell @ Belle (EPR experiment) Coherence between hadrons during their decays has been developed to test Bell inequality. Preliminary result based on semileptonic B-decays found 3σ away from prediction. This year shall wrap up for publication. One possible provision is to study coherency of their initial state and attempt to understand the origin of correlation in Quantum Mechanics. 研究期間：9308 ~ 9407
