17.03.2020

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Российские физики засекли новую частицу

 

Ученые Института ядерной физики (ИЯФ) СО РАН с помощью электронно-позитронного коллайдера ВЭПП-2000 обнаружили частицу нового типа - псевдовекторную частицу f1. Специалисты надеются, что открытие поможет им в изучении устройства мироздания, а также в поисках так называемой новой физики, которая выходит за рамки Стандартной модели.

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ТАСС Наука: https://nauka.tass.ru/nauka/7435127

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Связанные тематические статьи:

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1) Search for direct production of the f1(1285) resonance in e+e− collisions (10 January 2020)

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A search for direct production of the f1(1285) resonance in e+e− annihilation is performed with the SND detector at the VEPP-2000 e+e− collider. The analysis is based on data with an integrated luminosity of 15.1 pb−1 accumulated in the center-of-mass energy range 1.2–1.4 GeV. Two e+e− => f1(1285) candidate events are found at the peak of the resonance and zero events beyond the resonance. We consider this result as a first indication of the process e+e− => f1(1285). The measured branching fraction is consistent with the theoretical prediction.

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2) Consistent analysis of f1(1285) meson form factors (09.2019) (A.I. Milstein, A.S. Rudenko)

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Parameterization of the form factors of f1(1285) meson is proposed. This parameterization is consistent with the available experimental data on the cross sections of f1(1285) meson production in the processes e+e−→f1(1285) and e+e−→e+e−f1(1285), as well as on the widths of the decays f1(1285)→e+e−, f1(1285)→ρ0γ, f1(1285)→ρ0π+π−, and f1(1285)→2π+2π−. Our parameterization is also consistent with the predictions for the asymptotic behavior of these form factors.

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3) f1(1285) => e+e− decay and direct f1 production in e+e− collisions (10.2017) (A.S. Rudenko)

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The width of the f1(1285)→e+e− decay is calculated in the vector meson dominance model. The result depends on the relative phase between two coupling constants describing f1→ρ0γ decay. The width Γ(f1→e+e−) is estimated to be ≃0.07−0.19 eV. Direct f1 production in e+e− collisions is discussed, and the e+e−→f1→a0π→ηππ cross section is calculated. Charge asymmetry in the e+e−→ηπ+π− reaction due to interference between e+e−→f1 and e+e−→ηρ0 amplitudes is studied​.

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4) τ decay into a pseudoscalar and an axial-vector meson (11.2018) (L.R. Dai, L.Roca, E.Oset)

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We study theoretically the decay τ−→ντP−A, with P− a π− or K− and A an axial-vector resonance b1(1235), h1(1170), h1(1380), a1(1260), f1(1285) or any of the two poles of the K1(1270). The process proceeds through a triangle mechanism where a vector meson pair is first produced from the weak current and then one of the vectors produces two pseudoscalars, one of which reinteracts with the other vector to produce the axial resonance. For the initial weak hadronic production we use a recent formalism to account for the hadronization after the initial quark-antiquark pair produced from the weak current, which explicitly filters G-parity states and obtain easy analytic formulas after working out the angular momentum algebra. The model also takes advantage of the chiral unitary theories to evaluate the vector-pseudoscalar amplitudes, where the axial-vector resonances were obtained as dynamically generated from the VP interaction. We make predictions for invariant mass distribution and branching ratios for the channels considered.

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5) Vector and Axial-vector resonances in composite models of the Higgs boson (11.2016) (Diogo Buarque Franzosi, Giacomo Cacciapaglia, Haiying Cai, Aldo Deandrea, Mads Frandsen)

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We provide a non-linear realisation of composite Higgs models in the context of the SU(4)/Sp(4) symmetry breaking pattern, where the effective Lagrangian of the spin-0 and spin-1 resonances is constructed via the CCWZ prescription using the Hidden Symmetry formalism. We investigate the EWPT constraints by accounting the effects from reduced Higgs couplings and integrating out heavy spin-1 resonances. This theory emerges from an underlying theory of gauge interactions with fermions, thus first principle lattice results predict the massive spectrum in composite Higgs models. This model can be used as a template for the phenomenology of composite Higgs models at the LHC and at future 100 TeV colliders, as well as for other application. In this work, we focus on the formalism for spin-1 resonances and their bounds from di-lepton and di-boson searches at the LHC.

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