1. Search for tetraquark states ▫$X_{c c \bar{s} \bar{s}}$▫ in ▫$D_s^+ D_s^+$▫ (▫$D_s^{\ast +} D_s^{\ast +}$▫) final states at BelleX. Y. Gao, Jyotirmoi Borah, Marko Bračko, Samo Korpar, Peter Križan, Rok Pestotnik, Tomaž Podobnik, Samo Stanič, Marko Starič, Luka Šantelj, Valentina Zhukova, 2022, izvirni znanstveni članek Opis: A search for double-heavy tetraquark state candidates Xccs¯s¯ decaying to Dþ s Dþ s and Dþ s Dþ s is presented for the first time using the data samples of 102 × 106 ϒð1SÞ and 158 × 106 ϒð2SÞ events, and the data samples at ffiffi ps ¼ 10.52, 10.58, and 10.867 GeV corresponding to integrated luminosities of 89.5, 711.0, and 121.4 fb−1, respectively, accumulated with the Belle detector at the KEKB asymmetric energy electron-positron collider. The invariant-mass spectra of the Dþ s Dþ s and Dþ s Dþ s are studied to search for possible resonances. No significant signals are observed, and the 90% confidence level upper limits on the product branching fractions [Bðϒð1S; 2SÞ → Xccs¯s¯ þ anythingÞ × BðXccs¯s¯ → Dþ s Dþ s ðDþ s Dþ s ÞÞ] in ϒð1S; 2SÞ inclusive decays and the product values of Born cross section and branching fraction [σðeþe− → Xccs¯s¯ þ anythingÞ × BðXccs¯s¯ → Dþ s Dþ s ðDþ s Dþ s ÞÞ] in eþe− collisions at pffiffis ¼ 10.52, 10.58, and 10.867 GeV under different assumptions of Xccs¯s¯ masses and widths are obtained.
Ključne besede: tetraquark states, final states at Belle
Objavljeno v DKUM: 15.04.2025; Ogledov: 0; Prenosov: 3
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2. 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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3. Measurement of two-particle correlations of hadrons in ▫$e^+ e^-$▫ collisions at BelleY.-C. Chen, Marko Bračko, Samo Korpar, Peter Križan, Tomaž Podobnik, Marko Starič, Luka Šantelj, 2022, izvirni znanstveni članek Opis: The measurement of two-particle angular correlation functions in high-multiplicity e+e− collisions at √s=10.52 GeV is reported. In this study, the 89.5 fb−1 of hadronic e+e− annihilation data collected by the Belle detector at KEKB are used. Two-particle angular correlation functions are measured in the full relative azimuthal angle (Δϕ) and three units of pseudorapidity (Δη), defined by either the electron beam axis or the event-shape thrust axis, and are studied as a function of charged-particle multiplicity. The measurement in the thrust axis analysis, with mostly outgoing quark pairs determining the reference axis, is sensitive to the region of additional soft gluon emissions. No significant anisotropic collective behavior is observed with either coordinate analyses. Near-side jet correlations appear to be absent in the thrust axis analysis. The measurements are compared to predictions from various event generators and are expected to provide new constraints to the phenomenological models in the low-energy regime.
Ključne besede: Particle & resonance production, Quark & gluon jets, Quark-gluon plasma
Objavljeno v DKUM: 24.08.2023; Ogledov: 396; Prenosov: 9
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4. 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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5. Prisilna sredstva proti množici - primerjalno pravna ureditev : diplomsko delo univerzitetnega študijskega programa VarstvoslovjeTomaž Podobnik, 2019, diplomsko delo Opis: V diplomskem delu z naslovom »Prisilna sredstva proti množici- Primerjalno pravna ureditev« sem analiziral pravno ureditev prisilnih sredstev v Republiki Sloveniji ter osnovna načela, ki jih policisti morajo spoštovati pri uporabi prisilnih sredstev. V nadaljevanju sem opredelil vsa prisilna sredstva, ki jih slovenska policija sme uporabiti proti množici. Pri tem sem podrobneje opisal, kako ta prisilna sredstva ureja zakon, način uporabe določenega prisilnega sredstva in kako posamezno sredstvo deluje na osebe proti katerim se ga uporabi, ter kdo ima pravico in je pooblaščen, da odredi uporabo posamezna sredstva. V diplomskem delu sem podrobneje predstavil tudi posebno policijsko enoto, ki sodeluje pri vzdrževanju javnega reda na demonstracijah ter protestnih shodih. Pri tem sem opisal pravno podlago za ustanovitev enote ter sestavo enote. Pozornost sem usmeril tudi na usposabljanje te enote ter na njen poseben način kadrovanja. V diplomskem delu sem pozornost usmeril tudi na prav poseben fenomen psihologije množice. Delovanje množice ter način postopanja proti množici sta prav gotovo za policijo dve znanji, ki imata ključen pomen za uspešno nadzorovanje množice. V diplomskem delu sem predstavil nekaj definicij množic ter opredelil oblike množic, način delovanja množice ter njene lastnosti. Bistvo diplomskega dela je primerjava pravnih ureditev prisilnih sredstev proti množici s tujimi državami. Pravno ureditev prisilnih sredstev proti množici v Republiki Sloveniji sem primerjal še s tremi evropskimi državami – Republiko Hrvaško, Republiko Avstrijo ter Francosko Republiko. Pri tujih ureditvah sem iskal podobnosti s slovensko ureditvijo, še posebej pa sem pozornost posvečal razlikam na katere sem naletel med pregledom tujih zakonodaj. Na koncu diplome sledi še pregled policijske analize o aktivnostih policije na protestnih shodih leta 2012. V tem delu sem preučil uporabo prisilnih sredstev, poseben poudarek pa sem namenil prisilnim sredstvom proti množici. Pri tem me je predvsem zanimalo, kolikokrat je v omenjenem letu slovenska policija uporabila prisilna sredstva proti množici ter ali je bila njihova uporaba zakonita in strokovna.
Ključne besede: policija, policijska pooblastila, prisilna sredstva, pravna ureditev, diplomske naloge
Objavljeno v DKUM: 22.08.2019; Ogledov: 1789; Prenosov: 166
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