Evidence of K{sup +} {r_arrow} {pi}{sup +}{nu}{anti {nu}}: The BNL E787 1995 result (How did we get here)

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The kaon was studied very thoroughly since its discovery some 50 years ago. In the study of charged kaon branching ratios, it was noticed that K{sup +} {r_arrow} {pi}{sup 0}e{sup +}{nu}{sub e} is allowed while K{sup +} {r_arrow} {pi}{sup +}{nu}{anti {nu}} is not. The latter was then empirically classified as a forbidden decay, leading to the so called strangeness changing current rule. The decay K{sup +} {r_arrow} {pi}{sup 0}e{sup +}{nu}{sub e} is mediated by the strangeness changing charged current and its branching ratio is 4.8%. By contrast K{sup +} {r_arrow} {pi}{sup +}{nu}{anti {nu}} is a strangeness changing neutral current, which ... continued below

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15 p.

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Chiang, I.H. & Collaboration, E787 February 1, 1998.

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The kaon was studied very thoroughly since its discovery some 50 years ago. In the study of charged kaon branching ratios, it was noticed that K{sup +} {r_arrow} {pi}{sup 0}e{sup +}{nu}{sub e} is allowed while K{sup +} {r_arrow} {pi}{sup +}{nu}{anti {nu}} is not. The latter was then empirically classified as a forbidden decay, leading to the so called strangeness changing current rule. The decay K{sup +} {r_arrow} {pi}{sup 0}e{sup +}{nu}{sub e} is mediated by the strangeness changing charged current and its branching ratio is 4.8%. By contrast K{sup +} {r_arrow} {pi}{sup +}{nu}{anti {nu}} is a strangeness changing neutral current, which is forbidden. In 1970, the GIM model was introduced to explain this effect and in 1974, Gaillard and Lee calculated the K{sup +} {r_arrow} {pi}{sup +}{nu}{anti {nu}} branching ratio to be on the order of 10{sup {minus}10}. In the current theory, the K{sup +} {r_arrow} {pi}{sup +}{nu}{anti {nu}} is mediated by a Flavor Changing Neutral Current (FCNC) in which the cancellation of the three quark generations should be complete down to second order except for the difference in the quark masses. The top quark is much heavier than the charm and up quarks, so that the cancellation is not complete. In other words, this decay is more dependent on the top sector. The measurement of K{sup +} {r_arrow}{pi}{sup +}{nu}{anti {nu}} branching ratio measures the modulus of the V{sub td} element of the CKM Matrix. The 1995 results of E787 were published in 1997. This report is focused on how the author achieved the goal of detecting events with such as small branching ratio.

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15 p.

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INIS; OSTI as DE98004472

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  • International workshop on kaon, muon and neutrino physics and the future at High Energy Accelerator Research Organization (KEK), Tsukuba-shi (Japan), 31 Oct - 1 Nov 1997

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  • Other: DE98004472
  • Report No.: BNL--65258
  • Report No.: CONF-9710190--
  • Grant Number: AC02-76CH00016
  • Office of Scientific & Technical Information Report Number: 658360
  • Archival Resource Key: ark:/67531/metadc706362

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  • February 1, 1998

Added to The UNT Digital Library

  • Sept. 12, 2015, 6:31 a.m.

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  • Nov. 9, 2015, 12:03 p.m.

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Chiang, I.H. & Collaboration, E787. Evidence of K{sup +} {r_arrow} {pi}{sup +}{nu}{anti {nu}}: The BNL E787 1995 result (How did we get here), article, February 1, 1998; Upton, New York. (digital.library.unt.edu/ark:/67531/metadc706362/: accessed October 22, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.