M. Narain

Search for light gluinos

Abstract A study of radiative decays from 400 000 ϒ (9460)s in the partially upgraded CUSB detector is presented. We find evidence against the existence of gluinos of mass 0 6(GeV/ c 2 ) c 2 ) from a search for radiative ϒ (9460) decays into bound states of gluinos.

E 1 transitions from the Y'' state and the fine structure of the χ'b states

Using the CUSB-II detector at the Cornell Electron Storage Ring, we have made precision measurements of the electric dipole transition rates from Y« to χ b , which are in excellent agreement with theory. The fine-structure splitting is found to be M(χ b2 )-M(χ bl )=13.5±0.4±0.5 MeV and M(χ bl )-M(χ bo )=23.2 ± 0.7 ± 0.7 MeV, leading to a ratio R=0.584 ± 0.024 ± 0.02. The fine structure measures the relative contributions of the spin-orbit interaction a=9.5±0.2±0.1MeV and tensor interactionb=2.3±0.1±0.1 MeV

Study of π+π− transitions from the γ (3S) state

Abstract With the CUSB-II detector at CESR we have studied the processes γ (3S) → γ (1S) π + γ − and γ (3S) → γ (2S) π + π − , where the final state γ (1S or 2S) decays into a pair of leptons. We have found 451 γ (3S) → γ (1S) π + π − events and 138 γ (3S) → γ (2S) π + π − events. The corresponding branching ratios are (4.46 ± 0.34 ± 0.50)% and (4.82 ± 0.65 ± 0.53) % respectively, where the first error is statistical and the second systematic. The properties of the π + π − system have been studied and compared with several models.

CUSB-II: a high precision electromagnetic spectrometer

Abstract The design, construction and performance of a very compact precision electromagnetic spectrometer is described. The CUSB-II detector has been used to study ϒ spectroscopy, search for exotic particles and measure properties of the B and B ∗ mesons at the Cornell Electron Storage Ring.

Measurement of the B∗ cross section at s = 10.61 to 10.70 GeV☆

Abstract Using the CUSB-II detector at CESR we have measured the B ∗ cross section in the energy range from s = 10.61–10.65 GeV and 10.70 GeV to be 0.16±0.03 nb and 0.33±0.13 nb respectively. The photon energy for B ∗ →Bγ decays is measured to be 45.4±0.8 MeV, in agreement with our earlier determination. The implication of this measurement for future B factories is discussed.

Measurement of the branching ratio for Υ ’ ’ →μμ

Using the CUSB-II detector at the Cornell Electron Storage Ring, we have measured B..mu mu.., the branching fraction into muons, of the UPSILON meson. We find B/sub ..mu..//sub ..mu../(UPSILON) = (1.53 +- 0.33 +- 0.21)%, from which the UPSILON total decay width is 25.5 +- 5.0 keV. From this result we obtain ..cap alpha../sub s/ = 0.170/sub -0.012//sup +0.015/, ..lambda../sub M//sub S-bar/ = 148/sub -39//sup +56/ MeV. (MS-bar denotes the modified minimal-subtraction scheme).

E1 Transitions from the Upsilon " State and the Fine Structure of the chi b' States.

Using the CUSB-II detector at the Cornell Electron Storage Ring, we have made precision measurements of the electric dipole transition rates from Y« to χ b , which are in excellent agreement with theory. The fine-structure splitting is found to be M(χ b2 )-M(χ bl )=13.5±0.4±0.5 MeV and M(χ bl )-M(χ bo )=23.2 ± 0.7 ± 0.7 MeV, leading to a ratio R=0.584 ± 0.024 ± 0.02. The fine structure measures the relative contributions of the spin-orbit interaction a=9.5±0.2±0.1MeV and tensor interactionb=2.3±0.1±0.1 MeV

Measurement of the branching ratio forΥ’’→μμ

Using the CUSB-II detector at the Cornell Electron Storage Ring, we have measured B..mu mu.., the branching fraction into muons, of the UPSILON meson. We find B/sub ..mu..//sub ..mu../(UPSILON) = (1.53 +- 0.33 +- 0.21)%, from which the UPSILON total decay width is 25.5 +- 5.0 keV. From this result we obtain ..cap alpha../sub s/ = 0.170/sub -0.012//sup +0.015/, ..lambda../sub M//sub S-bar/ = 148/sub -39//sup +56/ MeV. (MS-bar denotes the modified minimal-subtraction scheme).

Measurement of the branching ratio for UPSILON/sup '//sup '/. --> mu mu

Using the CUSB-II detector at the Cornell Electron Storage Ring, we have measured B..mu mu.., the branching fraction into muons, of the UPSILON meson. We find B/sub ..mu..//sub ..mu../(UPSILON) = (1.53 +- 0.33 +- 0.21)%, from which the UPSILON total decay width is 25.5 +- 5.0 keV. From this result we obtain ..cap alpha../sub s/ = 0.170/sub -0.012//sup +0.015/, ..lambda../sub M//sub S-bar/ = 148/sub -39//sup +56/ MeV. (MS-bar denotes the modified minimal-subtraction scheme).