A measurement of the spin of the Omega(-) hyperon produced through the exclusive process Xi(c)(0)-->Omega(-)K(+) is presented using a total integrated luminosity of 116 fb(-1) recorded with the BABAR detector at the e(+)e(-) asymmetric-energy B factory at SLAC. Under the assumption that the Xi(c)(0) has spin 1/2, the angular distribution of the Lambda from Omega(-)-->LambdaK(-) decay is inconsistent with all half-integer Omega(-) spin values other than 3/2. Lower statistics data for the process Omega(c)(0)-->Omega(-)pi(+) from a 230 fb(-1) sample are also found to be consistent with Omega(-) spin 3/2. If the Xi(c)(0) spin were 3/2, an Omega(-) spin of 5/2 could not be excluded.

Sperm–egg fusion is indispensable for completing mammalian fertilization. Although the underlying molecular mechanisms are poorly understood, requirement of two spermatozoon factors, IZUMO1 and SPACA6, and two oocyte factors, CD9 and the IZUMO1 counter-receptor JUNO, has been proven by gene disruption, and the binding of cells to an oocyte can be reconstituted by ectopic expression of IZUMO1. Here we demonstrate that robust IZUMO1-dependent adhesion of sperm with an oocyte accompanies the dimerization of IZUMO1. Despite the intrinsic dimeric property of its N-terminal region, IZUMO1 is monomeric in spermatozoa. Interestingly, JUNO associates with monomeric IZUMO1, which is then quickly removed as tight adhesion of the two cells is subsequently established. We therefore propose that global structural rearrangement of IZUMO1 occurs on JUNO recognition and that this rearrangement may then initiate force generation to overcome repulsion between the juxtaposing membranes, through an unidentified receptor on the egg.

We study the reactions e + e − → e + e − η (′) in the single-tag mode and measure the γγ * → η (′) transition form factors in the momentum-transfer range from 4 to 40 GeV 2 . The analysis is based on 469 fb −1 of integrated luminosity collected at PEP-II with the BABAR detector at e + e − centerof-mass energies near 10.6 GeV.

We study the process e þ e − → e þ e − η 0 in the double-tag mode and measure for the first time the γ ⋆ γ ⋆ → η 0 transition form factor F η 0 ðQ 2 1 ; Q 2 2 Þ in the momentum-transfer range 2 < Q 2 1 , Q 2 2 < 60 GeV 2. The analysis is based on a data sample corresponding to an integrated luminosity of around 469 fb −1 collected at the PEP-II e þ e − collider with the BABAR detector at center-of-mass energies near 10.6 GeV.

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