BaBar Experiment :: Chemistry Science Scientific Essays

BaBar ExperimentAbstract I investigated the L = 1 mesons D*2(2460)0 and D1(2420)0 using data gathered by the BaBar demodulator at Pep-II. The decay process of these particles is interesting because it could serve to confirm or deny certain predictions make by HQET models. Thus far, the data gathered rougly conforms with measurements made by the CLEO and ARGUS collaborations. The data is still preliminary, however, and as such this paper should be considered merely a summary of the work done thus far. 1 Introduction1.1 The BaBar experimentThe BaBar sensing element at Pep-II was designed to study B mesons produced in asymmetric e+e- collisions. Asymmetric refers to the fact that the colliding electrons and positrons have different energies. This gives the resulting particles pulsation in the laboratory reference frame, allowing their lifetimes to be measured even if they carry away most of the collision energy. In the current run at Pep-II, electrons are stored in one ring at 9 GeV and positrons in the other at 3.1 GeV. This sets the collision energy right at the T(4S) resonance, a short-lived conclave of a bottom quark and its antiquark. This decays preferentially into a pair of mesons B and Bhence the name of the detector.Mesons are short-lived systems made up of a quark and an anti-quark Bs are mesons in which one quark is a bottom (or an anti-bottom) and the other is a light quark (up, down, strange, or their corresponding antiquarks). The BaBar detector is optimized to measure the decay process of these Bs as precisely as possible. It is hoped that differences between the B and the B decay processes will be uncovered and measured, which will lease to a better understanding of CP symmetry violation.CP violation describes an event that breaks the so-called Charge Parity symmetry. For a time, it was believed that if matter and antimatter were interchanged (hence, Charge) and if right and left were reversed (Parity), systems would stand in an identica l manner. This symmetry has since been found to be broken in certain kaon decays, and it is suspected that further violations will be discovered in B decays. Note that if time is reversed as well as charge and parity, then the system will behave in an indentical manner this is know as CPT symmetry, and is required for Lorentz transformations. It is hoped that learning more about events that violate the broken CP symmetry will shed some light on the relative scarceness of antimatter in the universe.