Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 1403.2667

On the disputed $π_1(1600)$ resonance and observation of a new iso-vector resonance

F. Nerling
View original source ↗Read source document ↗Export metadata ↓

Abstract

The COMPASS experiment at CERN delivers new results on the search for exotic mesons. A spin-exotic resonance, the $π_1(1600)$, was reported by several experiments in the past. Those observations are, however, still to date highly disputed in the community. Especially the $ρπ$ decay channel allows for simultaneous observation of well established and less known resonances in different decay modes. The results from amplitude analysis of diffractively produced $(3π)^{-}$ final states show consistently a spin-exotic signal, that appears in agreement with previous observations of the $π_1(1600)$. The high-statistics 2008 data sample allows and demands for an extended amplitude analysis method that further disentangles resonant and non-resonant particle production. The present status of analysis of COMPASS data and the observation of a new iso-vector meson $a_1(1420)$ is discussed.

Explore related subjects

hep-exhep-ph

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

F. Nerling. 2014-03-11. On the disputed $π_1(1600)$ resonance and observation of a new iso-vector resonance. https://arxiv.org/abs/1403.2667

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Dark photons in exotic Higgs boson decays at FCC-ee

A prospective search for dark photons decaying into collimated, displaced muon pairs is presented for the electron-positron stage of the Future Circular Collider, FCC-ee. Assuming the full luminosity of the Higgs run at 240 GeV, the study probes a broad range of dark photon masses and couplings. The signature comprises two jets from a Z boson decay and two muon pairs from dark photons produced in Higgs decays. A kinematics-based selection achieves zero background while retaining high signal efficiency. Expected limits are set on the Higgs boson branching ratio to dark photons as a function of the dark photon mass and coupling.

hep-ex↗
arXiv2026

Differential cross-section measurements of coherent production of singly and doubly resonant top-quark in $WWbb$ events with one lepton at $\sqrt{s}$ = 13 TeV with the ATLAS detector

This paper presents differential cross-section measurements of events containing a charged lepton, missing transverse momentum, two $b$-jets, and two light jets, consistent with the $W^{+}W^{-}b\bar{b}$ final state. The analysis is based on 140 fb$^{-1}$ of proton-proton collision data at $\sqrt{s}$ = 13 TeV recorded with the ATLAS detector during Run 2 of the Large Hadron Collider (2015-2018). Differential cross-sections are unfolded at particle level for a range of kinematic observables and in three kinematic regions. Both regions and observables are optimised for sensitivity to the interference between $W^{+}W^{-}b\bar{b}$ produced with singly and doubly resonant top quarks. Results are compared with various theoretical predictions. Significant discrepancies are observed in regions sensitive to the interference between singly and doubly resonant top-quark production. The unfolded results provide new information about the modelling of interference and off-shell effects of the $W^{+}W^{-}b\bar{b}$ final state, improving the understanding of top-quark production mechanisms and providing new inputs for future Monte Carlo generator development.

hep-ex↗
arXiv2026

Search for the reaction channel $e^+ e^- \to ηη\,J/ψ$ and the isospin partner of the $Z_c(3900)$ at center-of-mass energies $\sqrt{s} = 4.226-4.950$ GeV

We search for the reaction channel $e^+ e^- \to ηη\,J/ψ$ in a data sample with center-of-mass energies from 4.226 to 4.950 GeV that was collected by the BESIII detector operating at the Beijing Electron Positron Collider (BEPCII). The data analysis is performed with two different reconstruction methods, exclusive and semi-inclusive, enabling a comparison and combination of the results. Only at a few energy points a non-zero cross section is observed with a statistical significance of more than 3$σ$ using one of the methods. Therefore, the corresponding upper limits of the cross section at the 90% confidence level are determined. The energy dependent results show clear deviations from the the line shape expected from three-body phase space alone. Since the statistical significance for almost all center-of-mass energies is low, the upper limits for the reaction channel $e^+ e^- \to ηη\,J/ψ$ also serve as limits for the existence of a possible isospin partner to the charmonium-like isospin triplet $Z_{\rm c}(3900)$ which decays to $J/ψη$.

hep-ex↗