skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Attention:

The NSF Public Access Repository (PAR) system and access will be unavailable from 11:00 PM ET on Thursday, June 12 until 2:00 AM ET on Friday, June 13 due to maintenance. We apologize for the inconvenience.


Search for: All records

Creators/Authors contains: "Zhang, Z. P."

Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher. Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?

Some links on this page may take you to non-federal websites. Their policies may differ from this site.

  1. We report a search for a heavy neutral lepton (HNL) that mixes predominantly with ν τ . The search utilizes data collected with the Belle detector at the KEKB asymmetric energy e + e collider. The data sample was collected at and just below the center-of-mass energies of the ϒ ( 4 S ) and ϒ ( 5 S ) resonances and has an integrated luminosity of 915 fb 1 , corresponding to ( 836 ± 12 ) × 10 6 e + e τ + τ events. We search for production of the HNL (denoted N ) in the decay τ π N followed by its decay via N μ + μ ν τ . The search focuses on the parameter-space region in which the HNL is long-lived, so that the μ + μ originate from a common vertex that is significantly displaced from the collision point of the KEKB beams. Consistent with the expected background yield, one event is observed in the data sample after application of all the event-selection criteria. We report limits on the mixing parameter of the HNL with the τ neutrino as a function of the HNL mass. Published by the American Physical Society2024 
    more » « less
  2. This Letter reports the first measurement of the oscillation amplitude and frequency of reactor antineutrinos at Daya Bay via neutron capture on hydrogen using 1958 days of data. With over 3.6 million signal candidates, an optimized candidate selection, improved treatment of backgrounds and efficiencies, refined energy calibration, and an energy response model for the capture-on-hydrogen sensitive region, the relative ν ¯ e rates and energy spectra variation among the near and far detectors gives sin 2 2 θ 13 = 0.075 9 0.0049 + 0.0050 and Δ m 32 2 = ( 2.7 2 0.15 + 0.14 ) × 10 3 eV 2 assuming the normal neutrino mass ordering, and Δ m 32 2 = ( 2.8 3 0.14 + 0.15 ) × 10 3 eV 2 for the inverted neutrino mass ordering. This estimate of sin 2 2 θ 13 is consistent with and essentially independent from the one obtained using the capture-on-gadolinium sample at Daya Bay. The combination of these two results yields sin 2 2 θ 13 = 0.0833 ± 0.0022 , which represents an 8% relative improvement in precision regarding the Daya Bay full 3158-day capture-on-gadolinium result. Published by the American Physical Society2024 
    more » « less
    Free, publicly-accessible full text available October 1, 2025
  3. A<sc>bstract</sc> We report a search for the charged-lepton flavor violation in Υ(2S) →ℓτ±(ℓ=e, μ) decays using a 25 fb−1Υ(2S) sample collected by the Belle detector at the KEKBe+easymmetric-energy collider. We find no evidence for a signal and set upper limits on the branching fractions ($$ \mathcal{B} $$ B ) at 90% confidence level. We obtain the most stringent upper limits:$$ \mathcal{B} $$ B (Υ(2S)→ μτ±)<0.23×10−6and$$ \mathcal{B} $$ B (Υ(2S)→ eτ±)<1.12×10−6
    more » « less