Bulletin of the American Physical Society
APS April Meeting 2016
Volume 61, Number 6
Saturday–Tuesday, April 16–19, 2016; Salt Lake City, Utah
Session C2: DPF Prize Session - W.K.H. Panofsky PrizeInvited
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Sponsoring Units: DPF Chair: JoAne Hewett, Stanford University Room: Ballroom A |
Saturday, April 16, 2016 1:30PM - 1:57PM |
C2.00001: W.K.H. Panofsky Prize in Experimental Particle Physics: Establishing and testing the Standard Model of flavor physics ~. Invited Speaker: David Hitlin The discovery of an unexpectedly long $B$ meson lifetime made it feasible to measure the $CP$-violating asymmetry in $B$ meson decay. The measurement of these asymmetries were made by the $BABAR$ Collaboration at SLAC and the Belle Collaboration at KEK, using the PEP-II and KEKB asymmetric $e^+e^-$ colliders. The asymmetry in the decay rates of $B^0$ and $\bar{B}^0$ mesons to $CP$ eigenstate final states, due to a non-zero phase in the three quark generation CKM matrix, can be directly interpreted using the Unitarity Triangle construction in terms of the fundamental parameters of the matrix, with very little uncertainty due to hadronic effects. The measurement of these asymmetries in a wide variety of final states, which show complete consistency with the three-generation Standard Model, will be discussed. ~ The three following presentations will discuss in further detail the PEP-II and KEKB colliders, the $BABAR$ and Belle detectors, and aspects of the results other than those on $CP$-violation. ~ [Preview Abstract] |
Saturday, April 16, 2016 1:57PM - 2:24PM |
C2.00002: W.K.H. Panofsky Prize in Experimental Particle Physics: The BABAR Detector and PEP-II B Factory at SLAC Invited Speaker: Jonathan Dorfan The discovery and elucidation of CP violation in the B meson system presented daunting challenges for the accelerator and detector facilities. This talk discusses how these challenges were met and overcome in the electron-positron colliding-beam accelerator facility PEP-II and the associated BABAR detector at SLAC. The key challenge was to produce unprecedentedly large numbers of B mesons in a geometry that provided high-statistics, low-background samples of decays to CP eigenstates. This was realized with asymmetric collisions at the Y(4S) at peak luminosities in excess of 3×10$^{33}$/cm$^2$/sec. Specialized optics were developed to generate efficient, low background, multi-bunch collisions in an energy-asymmetric collision geometry. Novel technologies for the RF, vacuum and feedback systems permitted the storage of multi-amp, multi-bunch beams of electrons and positrons, thereby generating high peak luminosities. Accelerator uptimes greater than 95 percent, combined with high-intensity injection systems, ensured large integrated luminosity. PEP-II rapidly attained its design specifications and ultimately far exceeded the projected performance expectations for both peak and integrated luminosity. The BABAR detector, designed to efficiently reconstruct, flavor-tag and time-order entangled B meson decays at the Y(4S), performed at an unprecedented level of reliability. [Preview Abstract] |
Saturday, April 16, 2016 2:24PM - 2:51PM |
C2.00003: W.K.H. Panofsky Prize in Experimental Particle Physics: The B-factory at KEK Invited Speaker: Fumihiko Takasaki The B-Factory project at KEK is briefly described. It is an electron-positron collider, built by utilizing maximally the existing facilities built for the TRISTAN electron-positron collider. The electron ring is the one used for the TRISTAN collider, where-as the positron ring was built anew. Both rings were installed side-by-side in the same tunnel used for the TRISTAN collider. We adapted the finite angle collision scheme which were of some concern of some accelerator experts in the designs stage of the project from the view point of creating beam-beam instability. Thanks to the genius people of the KEK accelerator team, we have overcome the various problems of the accelerator and successfully achieved the luminosity higher that 10$^{\mathrm{34}}$ in the early days of the project. The adaptation of the finite angle crossing benefited to reduce the beam associated backgrounds and the operation of the accelerator and detector became much easier. The large circumference of the TRISTAN tunnel made the manipulation of the beam much easier. Contrary to the aggressive design of the B-Factory accelerator, the collider detector was the one consist of components based on the well-established technology. The detector of the experiment was operated successfully for years and we have accumulated sufficient number of B-meson pairs for the study of the CP asymmetry. We would like to briefly mention about the history of the Japanese high energy physics and also a close cooperation with the Japanese particle theory people, especially Makoto Kobayashi, Toshihide Maskawa, Ichiro Sanda and Hirotaka Sugawara. [Preview Abstract] |
Saturday, April 16, 2016 2:51PM - 3:18PM |
C2.00004: W.K.H. Panofsky Prize in Experimental Particle Physics: It wasn't only about \textit{CP}, or even $B$ mesons Invited Speaker: Stephen Lars Olsen Although the primary motivation and design theme for the $B$-factories and their experiments was the study of \textit{CP} violations in the $b$-quark sector and testing the Kobayashi-Maskawa suggestion that \textit{CP} violation could be incorporated into the Standard Model as an irreducible complex phase in the weak-interaction quark-flavor mixing matrix, both the BaBar and Belle research programs made a number of important measurements that had nothing to do with either \textit{CP} violation or the $b$-quark sector. These include the unexpected discovery of $D^{0}-D^{0}$\textit{bar} mixing and a number of charmoniumlike mesons with properties that do not match expectations for conventional charmed-quark anticharmed-quark (\textit{ccbar}) mesons. In principle, these state, which are now commonly known as the\textit{ XYZ} mesons, are described in the Standard Model by the long-distance regime of QCD, but, since first-principle long-distance QCD calculations are hopelessly difficult, a number of ``QCD-inspired'' models for nonstandard mesons have been proposed. Some of these attribute the \textit{XYZ} states to loosely bound meson-antimeson molecule-like structures, and others to tightly bound diquark-diantiquark tetraquarks, or quark-antiquark-gluon hybrids. None of the proposed models can give a comprehensive description of the spectrum of the observed states and their measured properties. In this talk I describe a few of the \textit{XYZ} mesons found by BaBar and Belle and why they are considered to be nonstandard. In addition I suggest some future measurements that could be done at BESIII, BelleII and Panda that might establish patterns that may help decipher some of the mysteries of long-distance QCD. Supported by project code IBS-R016-D [Preview Abstract] |
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