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1. Search for a pentaquark state decaying into pJ/ψ in Υ(1, 2S) inclusive decays at Belle

   https://doi.org/10.1007/JHEP09(2025)048  

   Dong, X; Zou, S M; Zhang, H Y; Wang, X L; Adachi, I; Ahn, J K; Aihara, H; Al_Said, S; Asner, D M; Atmacan, H; et al (September 2025, Journal of High Energy Physics)

   A<sc>bstract</sc> Using the data samples of 102 million Υ(1S) and 158 million Υ(2S) events collected by the Belle detector, we search for a pentaquark state in thepJ/ψfinal state from Υ(1,2S) inclusive decays. Here, the charge-conjugate$$\overline{p }J/\psi $$is included. We observe clearpJ/ψproduction in Υ(1,2S) decays and measure the branching fractions to be$$\mathcal{B}[\Upsilon (1S)\to pJ/\psi +anything]=[8.1\pm 0.6(stat.)\pm 0.5(syst.)]\times {10}^{-5}$$and$$\mathcal{B}[\Upsilon (2S)\to pJ/\psi +anything]=[4.3\pm 0.5(stat.)\pm 0.4(syst.)]\times {10}^{-5}$$. We also measure the cross section of inclusivepJ/ψproduction ine⁺e⁻annihilation to beσ(e⁺e⁻→pJ/ψ+anything) = [108 ± 11(stat.) ± 6(syst.)] fb at$$\sqrt{s}=10.52$$GeV using an 89.5 fb⁻¹continuum data sample. There is no significantP_c(4312)⁺,P_c(4440)⁺orP_c(4457)⁺signal found in thepJ/ψfinal states in Υ(1,2S) inclusive decays. We determine the upper limits of$$\mathcal{B}\left[\Upsilon \left({1},{2}S\right)\to {P}_{c}^{+}+anything\right]\cdot \mathcal{B}\left({P}_{c}^{+}\to pJ/\psi \right)$$to be at the 10⁻⁶level. 

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2. Study of Υ(10753) decays to π+π−Υ(nS) final states at Belle II

   https://doi.org/10.1007/JHEP07(2024)116  

   Adachi, I; Aggarwal, L; Ahmed, H; Aihara, H; Akopov, N; Aloisio, A; Anh_Ky, N; Asner, D M; Atmacan, H; Aushev, T; et al (July 2024, Journal of High Energy Physics)

   A<sc>bstract</sc> We present an analysis of the processe⁺e⁻→π⁺π⁻Υ(nS) (wheren= 1, 2, or 3) reconstructed in 19.6 fb⁻¹of Belle II data during a special run of the SuperKEKB collider at four energy points near the peak of the Υ(10753) resonance. By analyzing the mass distribution of theπ⁺π⁻Υ(nS) system and the Born cross sections of thee⁺e⁻→π⁺π⁻Υ(nS) process, we report the first observation of Υ(10753) decays to theπ⁺π⁻Υ(1S) andπ⁺π⁻Υ(2S) final states, and find no evidence for decays toπ⁺π⁻Υ(3S). Possible intermediate states in theπ⁺π⁻Υ(1S,2S) transitions are also investigated, and no evidence for decays proceeding via the$$ {\pi}^{\mp }{Z}_b^{\pm } $$ ${\pi }^{\mp }{Z}_b^{\pm }$ orf₀(980)Υ(nS) intermediate states is found. We measure Born cross sections for thee⁺e⁻→π⁺π⁻Υ(nS) process that, combined with results from Belle, obtain the mass and width of Υ(10753) to be (10756.6 ± 2.7 ± 0.9) MeV/c²and (29.0 ± 8.8 ± 1.2) MeV, respectively. The relative ratios of the Born cross sections at the Υ(10753) resonance peak are also reported for the first time. 

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3. Measurements of the mass difference m(B0) − m(B+) and the energy dependence of the cross-section ratio $$\sigma ({e}^{+}{e}^{-}\to {B}^{0}{\overline{B} }^{0})/\sigma ({e}^{+}{e}^{-}\to {B}^{+}{B}^{-})$$ at Belle and Belle II

   https://doi.org/10.1007/JHEP05(2026)172  

   Abumusabh, M; Adachi, I; Aggarwal, L; Ahmed, H; Ahn, Y; Aihara, H; Akopov, N; Alghamdi, S; Alhakami, M; Aloisio, A; et al (May 2026, Journal of High Energy Physics)

   A<sc>bstract</sc> Using data samples collected by the Belle and Belle II experiments at the Υ(4S) resonance with integrated luminosities of 571 fb⁻¹and 365 fb⁻¹, respectively, we measure the pseudoscalarB-meson mass difference to bem(B⁰) −m(B⁺) = (0.495 ± 0.024 ± 0.005) MeV/c². The results are based on a simultaneous fit to the variable$${\overline{M} }_{bc}$$, which is related to theBmomentum, forB⁰andB⁺candidates; and to the energy dependence of$$\mathcal{R}=\sigma ({e}^{+}{e}^{-}\to {B}^{0}{\overline{B} }^{0}) / \sigma ({e}^{+}{e}^{-}\to {B}^{+}{B}^{-})$$, which is measured using changes in the average center-of-mass energy over the data taking periods. The phase-space hypothesis$$\mathcal{R}={({p}_{{B}^{0}} /{p}_{{B}^{+}})}^{3}$$, upon which previous measurements rely, is strongly disfavored by our fit; the measured mass-difference value for the phase-space hypothesis also differs significantly from our measurement. We constrain$$\mathcal{R}$$in a broader energy range than covered by the direct measurement and extract the energy dependence of$$\mathcal{R}$$in the range from the$$B\overline{B }$$threshold up to 10.59 GeV. We interpret the results using a phenomenological model and constrain the parameters of the$$B\overline{B }$$potential in the isovector channel. 

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4. Search for charged-lepton flavor violation in Υ(2S) → ℓ∓τ± (ℓ = e, μ) decays at Belle

   https://doi.org/10.1007/JHEP02(2024)187  

   Dhamija, R; Nishida, S; Giri, A; Adachi, I; Aihara, H; Asner, D M; Aushev, T; Ayad, R; Babu, V; Bahinipati, S; et al (February 2024, Journal of High Energy Physics)

   A<sc>bstract</sc> We report a search for the charged-lepton flavor violation in Υ(2S) →ℓ^∓τ^±(ℓ=e, μ) decays using a 25 fb⁻¹Υ(2S) sample collected by the Belle detector at the KEKBe⁺e⁻asymmetric-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)→ μ^∓τ^±)<0.23×10⁻⁶and$$ \mathcal{B} $$ $B$ (Υ(2S)→ e^∓τ^±)<1.12×10⁻⁶. 

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5. Measurement of ω meson production in pp collisions at $$ \sqrt{s} $$ = 13 TeV

   https://doi.org/10.1007/JHEP04(2025)067  

   Acharya, S; Adamová, D; Agarwal, A; Aglieri_Rinella, G; Aglietta, L; Agnello, M; Agrawal, N; Ahammed, Z; Ahmad, S; Ahn, S U; et al (April 2025, Journal of High Energy Physics)

   A<sc>bstract</sc> Thep_T-differential cross section ofωmeson production in pp collisions at$$ \sqrt{s} $$ $\sqrt{s}$ = 13 TeV at midrapidity (|y| <0.5) was measured with the ALICE detector at the LHC, covering an unprecedented transverse-momentum range of 1.6< p_T<50 GeV/c. The meson is reconstructed via theω→π⁺π⁻π⁰decay channel. The results are compared with various theoretical calculations: PYTHIA8.2 with the Monash 2013 tune overestimates the data by up to 50%, whereas good agreement is observed with Next-to-Leading Order (NLO) calculations incorporatingωfragmentation using a broken SU(3) model. Theω/π⁰ratio is presented and compared with theoretical calculations and the available measurements at lower collision energies. The presented data triples thep_Tranges of previously available measurements. A constant ratio ofC^ω/π0= 0.578 ± 0.006 (stat.) ± 0.013 (syst.) is found above a transverse momentum of 4 GeV/c, which is in agreement with previous findings at lower collision energies within the systematic and statistical uncertainties. 

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