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Pardi, S.

Publications and source records attributed to Pardi, S..

8 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Azimuthal asymmetries of back-to-back π ± - ( π 0 , η , π ± ) pairs in e + e - annihilation

This work reports the first observation of azimuthal asymmetries around the thrust axis in e + e – annihilation of pairs of back-to-back charged pions in one hemisphere, and π 0 and η mesons in the opposite hemisphere. These results are complemented by a new analysis of pairs of back-to-back charged pions. The π 0 and η asymmetries rise with the relative momentum z of the detected hadrons as well as with the transverse momentum with respect to the thrust axis. These asymmetries are sensitive to the Collins fragmentation function $H$ $^{1}_{⊥}$ and provide complementary information to previous measurements with charged pions and kaons in the final state. In particular, the η final states will provide additional information on the flavor structure of $H$ $^{1}_{⊥}$. This is the first measurement of the explicit transverse-momentum dependence of the Collins fragmentation function from Belle data. It uses a dataset of 980.4 fb –1 collected by the Belle experiment at or near a center- of-mass energy of 10.58 GeV.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2017

Search for Λ c + → φ p π 0 and branching fraction measurement of Λ c + → K - π + p π 0

We have investigated the Cabibbo-suppressed decay Λ c + → φ p π 0 in e + e - collisions using a data sample corresponding to an integrated luminosity of 915 fb - 1 . The data were collected by the Belle experiment at the KEKB e + e - asymmetric-energy collider running at or near the Υ ( 4 S ) and Υ ( 5 S ) resonances. No significant signal is observed, and we set an upper limit on the branching fraction of B ( Λ c + → φ p π 0 ) < 15.3 × 10 - 5 at 90% confidence level. The contribution of nonresonant Λ c + → K + K - p π 0 decays is found to be consistent with zero, and the corresponding upper limit on its branching fraction is set to be B ( Λ c + → K + K - p π 0 ) NR < 6.3 × 10 - 5 at 90% confidence level. We also search for an intermediate hidden-strangeness pentaquark decay P s + → φ p . We see no evidence for this intermediate decay and set an upper limit on the product branching fraction of B ( Λ c + → P s + π 0 ) × B ( P s + → φ p ) < 8.3 × 10 - 5 at 90% confidence level. Finally, we measure the branching fraction for the Cabibbo-favored decay Λ c + → K - π + p π 0 ; the result is B ( Λ c + → K - π + p π 0 ) = ( 4.42 ± 0.05 ( stat ) ± 0.12 ( syst ) ± 0.16 ( norm ) ) % , which is the most decisive measurement to date.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗