Our overall goal is to rely on internal resources combined with  international cooperation through participation in the Belle-II and T2K experiments, to build a strong research group in the field of high energy physics (HEP), approaching world-class science, engineering and technology, and contributing to increasing the scientific and technical potential of the Institute of Physics (IOP), Vietnam Academy of Science and Technology (VAST).

(2) to perform technical tasks (which may be significant for the development of science and technology) important for the whole experiments’ operations.  

With the experiments Belle-II and T2K, we have achieved the following results

- Scientìic results:

● Precision measurements of  CP symmetry violation (CPV) and other physics quantities.

● Observation of flavor changing neutral currents at 3.5 sigma. It is an important result and is a signal of the NP. 

● Research on dark matter (localizing search regions).

● Research on neutrinos, CPV in the lepton sector and some processes involving neutrinos.

● Other New Physics issues:  lepton number universality, flavor changing neutral currents, etc.

● The Vietnamese (T2K and Belle-II) teams made significant contributions to technical issues that had a general effect on the operation of the experiment as well as the scientific results (publications) of the experiment.

● We are currently focusing more on studying heavy neutrinos. Participating in physical analysis of precise measurements of parameters of neutrino oscillations and CP symmetry violations;

● Participating in building new equipments, developing softwares, monitoring the operation of equipments and softwares of experiments.

● Participating in the management and operation of the experiments through representative councils/committees.

● Training (in Viet Nam) PhD and M.Sc in HEP. Organizing different activities to train working forces for HEP.

● Using and developing NEUT software to simulate the interaction of neutrinos with the nucleus;

● and as from 2018, the Vietnamese T2K team began participating in WAGASCI - an experiment focusing on measuring neutrino interactions with nuclei.

 

- Applied results: 

   Our work is basic research so there are no direct applied results yet, but experimental research is a bridge between basic science and technological applications. We have achieved the following results (which could be classified as pre-application). 

With the Belle-II experiment: 

   Through direct participation in the process of building and operating the CDC, we have accessed some technical knowledge as well as contributed significantly to the experimental operation process (as mentioned above and in the seminar by Dong Van Thanh "Belle/Belle II experiment and activities of the Vietnamese group", at the Institute of Physics, June 7, 2023). These harvests will be useful for developing a number of science and technology directions in the future if they receive enough investment and attention from science and technology organizations/agencies.

With the T2K experiment:

- Participating in the construction of new equipments for non-destructive proton flow monitoring;

- Participating in monitoring neutrino beam generation activities at J-PARC;

- Participating in building the INGRID and SuperFGD near detector systems of the T2K experiment;

- The T2K-Vietnam group has conducted its own research with equipment located in Quy Nhon and has initially achieved positive results, laying the basis for mastering equipment and related technology.

- Scientific papers in refereed journals (list):

1.      Search for lepton-flavor-violating τ decays to a lepton and an invisible boson at Belle II,, The Belle II collaboration (I. Adachi, ..., N. Anh Ky, …, T.V. Dong, …),
  PHYSICAL REVIEW LETTERS 130, 181803 (2023).

2.      Measurement of the B0 lifetime and flavor-oscillation frequency using hadronic decays reconstructed in 2019–2021 Belle II data
The Belle II collaboration (F. Abudinén, ..., , ..., N. Anh Ky, …, T.V. Dong, …),
  PHYSICAL REVIEW D 107, L091102 (2023).

3.      Search for an invisible Z0 in a final state with two muons and missing energy at Belle II, , The Belle II collaboration (I. Adachi, ..., N. Anh Ky, …, T.V. Dong, …),
 Phys. Rev. D 130, 231801 (2023).

4.      Measurement of the branching fraction and CP asymmetry of B0 → π0π0 decays using 198 × 10 6 B\bar{B} pairs in Belle II data,
The Belle II collaboration (F. Abudinén, ..., N. Anh Ky, …, T.V. Dong, …),
 Phys. Rev. D 107, 112009 (2023).

5.      Novel method for the identification of the production flavor of neutral charmed mesons, , The Belle II collaboration (I. Adachi, ..., N. Anh Ky, …,T.V. Dong, …)
 Phys. Rev. D 107, 112010 (2023).

6.      Test of light-lepton universality in the rates of inclusive semileptonic B-meson decays at Belle II, The Belle II collaboration (L. Aggarwal, ..., N. Anh Ky, …, T.V. Dong, …),
 Phys. Rev. Lett. 131, 051804 (2023).

7.      Measurement of the τ-lepton mass with the Belle II experiment,
The Belle II collaboration (I. Adachi, ..., N. Anh Ky, …, T.V. Dong, …),
  Phys. Rev. D 108, 032006 (2023).

8.      Measurement of CP violation in B0 → K0Sπ0 decays at Belle II,
The Belle II collaboration (I. Adachi, ..., N. Anh Ky, …, T.V. Dong, …),
  Phys. Rev. Lett. 131, 111803 (2023).

9. Search for a τ+ τ− resonance in e+ e− → μ+ μ− τ+ τ− events with the Belle II experiment, , The Belle II collaboration (I. Adachi, ..., N. Anh Ky, …, T.V. Dong, …),
 Phys. Rev. Lett. 131, 121802 (2023).

10.  Measurement of CP asymmetries and branching-fraction ratios for B±→DK± and Dπ± with D→K0SK±π∓ using Belle and Belle II data,
The Belle II collaboration (I. Adachi, ..., N. Anh Ky, ...),
  Journal of High Energy Physics 09, 146 (2023).

11.  Measurement of CP asymmetries in B0 → ϕK0s decays with Belle II,
The Belle II collaboration (I. Adachi, ..., N. Anh Ky, …, T.V. Dong, …),
  Phys. Rev.  D 108, , 072012 (2023).

12.  Observation of e + e − → ω χ b J ( 1 P ) and search for Xb → ω Υ (1S) at √s near 10.75 GeV, , I. Adachi, , ..., N. Anh Ky, …, T.V. Dong, et al. [Belle II collaboration],
  Phys. Rev. Lett. 130, 091902 (2023).

13.  Search for a dark photon and an invisible dark Higgs boson in μ+ μ− and missing energy final states with the Belle II experiment,
F. Abudinén,, ..., N. Anh Ky, …, T.V. Dong, et al. [Belle II collaboration],
 Phys. Rev. Lett. 130, 071804 (2023).

14.  Measurement of the Λ+c lifetime,
F. Abudinén, , ..., N. Anh Ky, …, T.V. Dong, et al. [Belle II collaboration],
 Phys. Rev. Lett. 130, 071802 (2023).

15.  Measurement of the Ω0c lifetime at Belle II,
F. Abudinén, ..., N. Anh Ky, …, T.V. Dong, et al. [Belle II collaboration],
   Phys. Rev. D 107, L031103 (2023).

16.  Measurement of lepton mass squared moments in B → Xc ℓ\bar{ν}ℓ decays with the Belle II experiment,
F. Abudinén, , ..., N. Anh Ky, …, T.V. Dong,  et al. [Belle II collaboration],
 Phys. Rev. D 107, 072002 (2023).

17.  Combined analysis of Belle and Belle II data to determine the CKM angle ∅3 using B^+→D(KS^0 h^+ h^- ) h^+ decays,
The Belle II collaboration (F. Abudinén, ..., N. Anh Ky, , ..., N. Anh Ky, …, T.V. Dong, ...), Journal of High Energy Physics 2022, 63 (2022).

18.  Search for B+ → K+ νν¯ decays using an inclusive tagging method at Belle II,
The Belle II collaboration (F. Abudinén, …, N. Anh Ky, …, T.V. Dong, ...),
 Phys. Rev. Lett. 127, 181802 (2021).

19.  Determination of |Vcb| using ¯B0→D∗+ℓ−¯νℓ decays with Belle II ,

The Belle II collaboration (I. Adachi, ..., N. Anh Ky, …, T.V. Dong, …),

Phys. Rev. D 108, 092013 (2023).

20.  Tests of light-lepton universality in angular asymmetries of hadronically tagged B0→D∗−ℓ+ν decays at Belle II

The Belle II collaboration (I. Adachi, ..., N. Anh Ky, …, T.V. Dong, …),

Phys. Rev. Lett. 131, 18180; arXiv:2308.02023 

21.  Measurement of branching fractions and direct CP asymmetries for B→Kπ and B→ππ decays at Belle II,

The Belle II collaboration (I. Adachi, ..., N. Anh Ky, …, T.V. Dong, …),

Phys. Rev.  D 109, 012001 (2024).

22.  Precise measurement of the D+s lifetime at Belle II,

The Belle II collaboration (I. Adachi, ..., N. Anh Ky, …, T.V. Dong, …),

Phys. Rev. Lett. 131, 171803 (2023), arXiv:2306.00365.

23.  B-flavor tagging at Belle II

The Belle II collaboration (F. Abudinén, ,,,, T. V. Dong, et al),

Eur. Phys. J. C 82, 283 (2022).

24.  Precise Measurement of the D0 and D+ lifetimes at Belle II,
The  II collaboration (F. Abudinén, ..., N. Anh Ky, …, T.V. Dong, …),
  PHYSICAL REVIEW LETTERS 127, 211801 (2021).

25.  Updated T2K measurements of muon neutrino and antineutrino disappearance using 3.6 × 10^21 protons on targe,
The T2K collaboration (K. Abe, ..., N. T. Hong Van, …, T. V. Ngoc, …),
  PHYSICAL REVIEW D 108, 072011 (2023).

26.  Measurements of the νμ and ν¯μ-induced coherent charged pion production cross sections on 12C by the T2K experiment,

The T2K collaboration (K. Abe, ..., N. T. Hong Van, ..., T. V. Ngoc, …),
 Phys. Rev. D 108, 092009 (2023).

27.  Improved constraints on neutrino mixing from the T2K experiment with 3.13 × 1021 protons on target,
The T2K collaboration (K. Abe, ..., N. T. Hong Van, ..., T. V. Ngoc, …),
 Phys. Rev. D 103, 112008 (2021).

28.  First T2K measurement of transverse kinematic imbalance in the muon-neutrino charged-current single-π+ production channel containing at least one proton,
The T2K collaboration (K. Abe, ..., N. T. Hong Van, ..., T. V. Ngoc, …),
 Phys. Rev. D 103, 112009 (2021).