arXiv subjects

Viktoriia Ermolina

Publications and source records attributed to Viktoriia Ermolina.

3 recordsLinked to original sources

arXiv2026

Simultaneous Dalitz-plot decomposition of the $e^+ e^- \to J/ψ\, π\, π\, (K \bar{K})$ processes in the 4.13-4.36 GeV region using dispersive final-state interactions

We present a joint analysis of the processes $e^+e^- \to J/ψπ^+π^-$ and $e^+e^- \to J/ψK^+K^-$ at center-of-mass energies from 4.13 to 4.36 GeV. The amplitudes are constructed using the Dalitz-plot decomposition formalism, with the $e^+e^-$ energy dependence encoded through the $Y(4220)$ and $Y(4320)$ resonant structures together with a non-resonant production mechanism. The scalar $ππ/K\bar K$ final-state interaction is treated dispersively using a coupled-channel Omnès representation. This allows us to describe the measured total cross sections and one-dimensional invariant-mass distributions with a single set of energy-independent parameters. We find that a purely resonant description of the BESIII data is insufficient, requiring a non-resonant term at the amplitude level which undergoes $ππ/K\bar{K}$ rescattering. Within the present isobar model, we extract Breit-Wigner parameters for the $Z_c(3900)$, $Y(4220)$, and $Y(4320)$ states, and determine the corresponding subprocess cross sections.

hep-ph↗

arXiv2025

Dalitz-plot decomposition for the $e^+ e^- \to J/ψ\, π\, π\, (K \bar{K})$ and $e^+ e^- \to h_c \, π\, π$ processes

We present an analysis of the $e^+ e^- \to γ^* \to J/ψ\, π\, π\, (K \bar{K})$ and $e^+ e^- \to γ^* \to h_c \, π\, π$ processes employing the recently proposed Dalitz-plot decomposition approach, which is based on the helicity formalism for three-body decays. For the above reactions, we validate the factorization of the overall rotation for all decay chains and spin alignments, along with the crossing symmetry between final states, using a Lagrangian-based toy model. For the model-dependent factors that describe the subchannel dynamics, we employ the dispersive treatment of the $π\, π\, (K \bar{K})$ final state interaction, which accurately reproduces pole positions and couplings of the $f_0(500)$ and $f_0(980)$ resonances. The constructed amplitudes serve as an essential framework to further constrain the properties of the charged exotic states $Z_c(3900)$ and $Z_c(4020)$, produced in these reactions.

hep-ph↗

arXiv2024

Pion polarizabilities from a dispersive analysis of $γγ\to ππ$

We present results for the charged and neutral pion polarizabilities, obtained through a dispersive analysis of photon-fusion reactions with two pions in the final state. This analysis is motivated by current and future measurements at COMPASS, JLab (Hall D), and the BESIII measurement of single-virtual photon-fusion reactions in the space-like region, offering insight into generalized pion polarizabilities. To improve predictions within an unsubtracted dispersion formalism with only the pion left-hand cut, one needs to consider the influence of heavier left-hand cuts. We parametrize the latter using an expansion in a suitably constructed conformal variable, capturing the analytical structure of the left-hand cuts. The coefficients in this expansion are determined from the matching with the Lagrangian-based approach, the Adler zero constraint for $γγ\to π^0π^0$, and a fit to the cross-section data. The extension to the single-virtual case is also discussed.

hep-ph↗