1. Search for ▫$Z^\prime \to \mu^+ \mu^-$▫ in the ▫$L_\mu - L_\tau$▫ gauge-symmetric model at BelleT. Czank, Karol Adamczyk, Jyoti Prakash Biswal, Marko Bračko, Boštjan Golob, Samo Korpar, Peter Križan, Manca Mrvar, Rok Pestotnik, Tomaž Podobnik, Samo Stanič, Marko Starič, Luka Šantelj, 2022, izvirni znanstveni članek Opis: We search for a new gauge boson Z′ that couples only to heavy leptons and their corresponding neutrinos in the process e+e−→Z′(→μ+μ−)μ+μ−, using a 643 fb−1 data sample collected by the Belle experiment at or near the Υ(1S,2S,3S,4S,5S) resonances at the KEKB collider. While previous searches for Z′ performed a data-based estimation of the initial state radiation effect, our search for the Z′ is the first to include effects due to initial state radiation in the signal simulated samples that were used in estimating the detection efficiency. No signal is observed in the Z′ mass range of 0.212–10 GeV/c2, and we set an upper limit on the coupling strength, g′, constraining the possible Z′ contribution to the anomalous magnetic dipole moment of the muon.
Ključne besede: Extensions of gauge sector, leptonic, semileptonic & radiative decays
Objavljeno v DKUM: 25.09.2023; Ogledov: 455; Prenosov: 39
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2. Measurement of the branching fraction and ▫$CP$▫ asymmetry for ▫$B \to \bar{D}^0 \pi$▫ decaysT. Bloomfield, Jyoti Prakash Biswal, Marko Bračko, Samo Korpar, Peter Križan, Rok Pestotnik, Tomaž Podobnik, Marko Starič, Luka Šantelj, 2022, izvirni znanstveni članek Opis: We measure the branching fractions and CP asymmetries for the decays B⁰ → D¯ 0π⁰ and B⁺ → D¯ 0π⁺, using a data sample of 772 × 10⁶ BB¯ pairs collected at the ϒ(4S) resonance with the Belle detector at the KEKB e⁺e− collider. The branching fractions obtained and direct CP asym-metries are B(B⁰ → D¯ 0π⁰)=[2.70 0.06(stat) 0.10(syst)]×10−⁴, B(B⁺ → D¯ 0π⁺)=[4.53 0.02(stat) 0.15(syst)]×10−³, ACP(B⁰ → D¯ 0π⁰)= [+0.42 2.05(stat) 1.22(syst)]%, and ACP(B⁺ → D¯ 0π⁺) = [+0.19 0.36(stat) 0.57(syst)]%. The measurements of B are the most precise to date and are in good agreement with previous results, as is the measurement of ACP(B⁺ → D¯ 0π⁺). The measurement of ACP for B⁰ → D¯ 0π⁰ is the first for this mode, and the value is consistent with Standard Model expectations.
Ključne besede: branching fraction, hadronic decays, particle decays, mesons, CP violation, precision measurements
Objavljeno v DKUM: 17.08.2023; Ogledov: 364; Prenosov: 39
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3. Search for the decay ▫$B_s^0 \to \eta \eta$▫S. Bhuyan, Jyoti Prakash Biswal, Marko Bračko, Boštjan Golob, Samo Korpar, Peter Križan, Rok Pestotnik, Marko Starič, Luka Šantelj, 2022, izvirni znanstveni članek Opis: We report results from a search for the decay B0s→ηη using 121.4 fb−1 of data collected at the Υ(5S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. We do not observe any signal and set an upper limit on the branching fraction of 14.3×10−5 at 90% confidence level. This result represents a significant improvement over the previous most stringent limit.
Objavljeno v DKUM: 17.08.2023; Ogledov: 270; Prenosov: 34
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4. First model-independent Dalitz analysis of $B^0 \to D^0K^{\ast 0}$, $D\to K_S^0\pi ^+\pi ^-$ decayK. Negishi, Jyoti Prakash Biswal, Marko Bračko, Boštjan Golob, Samo Korpar, Peter Križan, Tara Nanut, Rok Pestotnik, Marko Petrič, Eva Ribežl, Samo Stanič, Marko Starič, Luka Šantelj, Anže Zupanc, 2016, izvirni znanstveni članek Opis: We report a measurement of the amplitude ratio $r_S$ of $B^0 \to D^0K^{\ast 0}$ and $B^0 \to \bar {D^0}K^{\ast 0}$ decays with a Dalitz analysis of $D\to K_S^0\pi ^+\pi ^-$ decays, for the first time using a model-independent method. We set an upper limit $r_S < 0.87$ at the 68% confidence level, using the full data sample of $711\,{\rm fb}^{-1}$ corresponding to $772\times 10^6$ $B\bar {B}$ pairs collected at the $\Upsilon (4S)$ resonance with the Belle detector at the KEKB $e^+e^-$ collider. This result is obtained from observables $x_- = +0.4 ^{+1.0 +0.0}_{-0.6 -0.1} \pm 0.0$, $y_- = -0.6 ^{+0.8 +0.1}_{-1.0 -0.0} \pm 0.1$, $x_+ = +0.1 ^{+0.7 +0.0}_{-0.4 -0.1} \pm 0.1$, and $y_+ = +0.3 ^{+0.5 +0.0}_{-0.8 -0.1} \pm 0.1$, where $x_\pm = r_S \cos (\delta _S \pm \phi _3)$, $y_\pm = r_S \sin (\delta _S \pm \phi _3)$, and $\phi _3\ (\delta _S)$ is the weak (strong) phase difference between $B^0 \to D^0K^{\ast 0}$ and $B^0 \to \bar {D^0}K^{\ast 0}$.
Ključne besede: CO2, CO3, Cabibbo-Kobayashi-Maskawa quark-mixing matrix, CP violation, experimental particle physics
Objavljeno v DKUM: 21.07.2017; Ogledov: 1788; Prenosov: 309
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5. Measurement of D0–D‾0 mixing and search for CP violation in D0 → K+K−,π+π− decays with the full Belle data setMarko Starič, Jyoti Prakash Biswal, Marko Bračko, Boštjan Golob, Samo Korpar, Peter Križan, Tara Nanut, Rok Pestotnik, Marko Petrič, Eva Ribežl, Samo Stanič, Anže Zupanc, 2016, izvirni znanstveni članek Opis: We report an improved measurement of $D^0–{\overline{D}}^0$ mixing and a search for $CP$ violation in $D^0$ decays to $CP$ -even final states $K^+K^−$ and $\pi^+\pi^-$. The measurement is based on the final Belle data sample of $976 fb^{−1}$. The results are $y_CP=(1.11±0.22±0.09)%$ and $A_Γ=(−0.03±0.20±0.07)%$, where the first uncertainty is statistical and the second is systematic.
Ključne besede: charm mesons, mixing, CP violation
Objavljeno v DKUM: 17.07.2017; Ogledov: 1520; Prenosov: 451
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