1.
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The $\pi^+\pi^-$ Coulomb interaction study and its use in the data processing
/ Adeva, B. (Santiago de Compostela U.) ; Afanasyev, L. (Dubna, JINR) ; Anania, A. (INFN, Messina) ; Aogaki, S. (Bucharest, IFIN-HH) ; Benelli, A. (Prague, Tech. U.) ; Brekhovskikh, V. (Serpukhov, IHEP) ; Cechak, T. (Prague, Tech. U.) ; Chiba, M. (Tokyo Metropolitan U.) ; Chliapnikov, P. (Serpukhov, IHEP) ; Drijard, D. (Prague, Tech. U. ; CERN) et al.
In this work the Coulomb effects (Coulomb correlations) were studied using experimental $\pi^+\pi^-$ pair distributions in $Q$, the relative momentum in the pair center of mass system (c.m.s), and its projections $Q_L$ (longitudinal component) and $Q_t$ (transverse component) relative to the pair direction in the laboratory system (l.s.). The major part of the pion pairs is produced by decay of $\rho, \omega$ and $\Delta$ and other short-lived sources (Coulomb pairs). [...]
arXiv:2409.12696; CERN-EP-2023-276.-
Geneva : CERN, 2024-11-01 - 11 p.
- Published in : Phys. Rev. D 110 (2024) 092005
Draft (restricted): PDF; Fulltext: DIRAC-Coulomb-correct - PDF; 2409.12696 - PDF;
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2.
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Investigation of $K^+K^-$ pairs in the effective mass region near $2m_K$
/ DIRAC Collaboration
The DIRAC experiment at CERN investigated in the reaction $\rm{p}(24~\rm{GeV}/c) + Ni$ the particle pairs $K^+K^-, \pi^+ \pi^-$ and $p \bar{p}$ with relative momentum $Q$ in the pair system less than 100 MeV/c. Because of background influence studies, DIRAC explored three subsamples of $K^+K^-$ pairs, obtained by subtracting -- using time-of-flight (TOF) technique -- background from initial $Q$ distributions with $K^+K^-$ sample fractions more than 70%, 50% and 30%. [...]
arXiv:2204.01857; CERN-EP-2022-058.-
2022-08-01 - 18 p.
- Published in : Phys. Rev. D 106 (2022) 032006
Fulltext: PhysRevD.106.032006 - PDF; 2204.01857 - PDF;
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3.
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4.
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Exotic meson $\pi_1(1600)$ with $J^{PC} = 1^{-+}$ and its decay into $\rho(770)\pi$
/ COMPASS Collaboration
We study the spin-exotic $J^{PC} = 1^{-+}$ amplitude in single-diffractive dissociation of 190 GeV$/c$ pions into $\pi^-\pi^-\pi^+$ using a hydrogen target and confirm the $\pi_1(1600) \to \rho(770) \pi$ amplitude, which interferes with a nonresonant $1^{-+}$ amplitude. We demonstrate that conflicting conclusions from previous studies on these amplitudes can be attributed to different analysis models and different treatment of the dependence of the amplitudes on the squared four-momentum transfer and we thus reconcile their experimental findings. [...]
arXiv:2108.01744; CERN-EP-2021–162.-
2022-01-01 - 30 p.
- Published in : Phys. Rev. D 105 (2022) 012005
Fulltext: 2108.01744 - PDF; PhysRevD.105.012005 - PDF;
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5.
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Discovering true tauonium via two-photon fusion at $e^+e^-$ and hadron colliders
/ d'Enterria, David (CERN) ; Shao, Hua-Sheng (Paris, LPTHE)
The feasibility of observing true tauonium, the bound state of two tau leptons, $\mathcal{T}_0\equiv(\tau^+\tau^-)_0$, via photon-photon collisions at $e^+e^-$ colliders and at the LHC, is studied. The production cross sections of the process $\gamma\gamma\to\mathcal{T}_0\to\gamma\gamma$-- as well as those of all relevant backgrounds: spin-0 and 2 charmonium resonances decaying to diphotons, and light-by-light scattering -- are computed in the equivalent photon approximation for $e^+e^-$ collisions at BES III ($\sqrt{s} = 3.8$ GeV), Belle II ($\sqrt{s} = 10.6$ GeV), and FCC-ee ($\sqrt{s} = 91.2$ GeV), as well as for ultraperipheral p-p, p-Pb, and Pb-Pb collisions at the LHC. [...]
arXiv:2202.02316.-
2022-05-01 - 9 p.
- Published in : Phys. Rev. D 105 (2022) 093008
Fulltext: PDF;
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6.
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A Triangle Singularity as the Origin of the $a_1(1420)$
/ Alexeev, G.D. (Dubna, JINR) ; Alexeev, M.G. (Turin U. ; INFN, Turin) ; Amoroso, A. (Turin U. ; INFN, Turin) ; Andrieux, V. (CERN ; Illinois U., Urbana) ; Anosov, V. (Dubna, JINR) ; Antoshkin, A. (Dubna, JINR) ; Augsten, K. (Dubna, JINR ; CTU, Prague) ; Augustyniak, W. (NCBJ, Warsaw) ; Azevedo, C.D.R. (Aveiro U.) ; Badełek, B. (Warsaw U.) et al.
The COMPASS experiment recently discovered a new isovector resonance-like signal with axial-vector quantum numbers, the $a_1(1420)$, decaying to $f_0(980)\pi$. With a mass too close to and a width smaller than the axial-vector ground state $a_1(1260)$, it was immediately interpreted as a new light exotic meson, similar to the $X$, $Y$, $Z$ states in the hidden-charm sector. [...]
arXiv:2006.05342; CERN-EP-2020-104.-
Geneva : CERN, 2021-08-18 - 21 p.
- Published in : Phys. Rev. Lett.
Draft (restricted): PDF; Fulltext: CERN-EP-2020-104 - PDF; 2006.05342 - PDF;
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Measurement of the Charged-Pion Polarizability
/ COMPASS Collaboration
The COMPASS collaboration at CERN has investigated pion Compton scattering, $\pi^-\gamma\rightarrow \pi^-\gamma$, at centre-of-mass energy below 3.5 pion masses. The process is embedded in the reaction $\pi^-\mathrm{Ni}\rightarrow\pi^-\gamma\;\mathrm{Ni}$, which is initiated by 190 GeV pions impinging on a nickel target. [...]
arXiv:1405.6377; CERN-PH-EP-2014-109; CERN-PH-EP-2014-109.-
Geneva : CERN, 2015-02-10 - 6 p.
- Published in : Phys. Rev. Lett. 114 (2015) 062002
APS Open Access article: PDF; Draft (restricted): PDF; Fulltext: arXiv:1405.6377 - PDF; CERN-PH-EP-2014-109 - PDF; External link: Interactions.org article
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9.
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Exclusive $\omega$ meson muoproduction on transversely polarised protons
/ COMPASS Collaboration
Exclusive production of $\omega$ mesons was studied at the COMPASS experiment by scattering $160~\mathrm{GeV}/\mathit{c}$ muons off transversely polarised protons. Five single-spin and three double-spin azimuthal asymmetries were measured in the range of photon virtuality $1~(\mathrm{GeV}/\mathit{c})^2 < Q^2 < 10~(\mathrm{GeV}/\mathit{c})^2$, Bjorken scaling variable $0.003 < x_{\mathit{Bj}} < 0.3$ and transverse momentum squared of the $\omega$ meson $0.05~(\mathrm{GeV}/\mathit{c})^2 < p_{T}^{2} < 0.5~(\mathrm{GeV}/\mathit{c})^2$. [...]
arXiv:1606.03725; CERN-EP-2016-157.-
Geneva : CERN, 2017-02 - 22 p.
- Published in : Nucl. Phys. B 915 (2017) 454-475
Article from SCOAP3: PDF; Fulltext: arXiv:1606.03725 - PDF; 1606.03725 - PDF; External link: Preprint
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10.
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Probing Neutral Triple Gauge Couplings at the LHC and Future Hadron Colliders
/ Ellis, John (King's Coll. London ; CERN ; NICPB, Tallinn ; Tsung-Dao Lee Inst., Shanghai ; SKLPPC, Shanghai) ; He, Hong-Jian (Tsung-Dao Lee Inst., Shanghai ; SKLPPC, Shanghai ; Tsinghua U., Beijing ; Tsinghua U., Beijing, CHEP) ; Xiao, Rui-Qing (King's Coll. London ; Tsung-Dao Lee Inst., Shanghai ; SKLPPC, Shanghai)
We study probes of neutral triple gauge couplings (nTGCs) at the LHC and the proposed 100TeV $pp$ colliders, and compare their sensitivity reaches with those of the proposed $e^+ e^-$ colliders. The nTGCs provide a unique window to the new physics beyond the Standard Model (SM) because they can arise from SM effective field theory (SMEFT) operators that respect the full electroweak gauge group $SU(2)_L\otimes U(1)_Y$ of the SM only at the level of dimension-8 or higher. [...]
arXiv:2206.11676; KCL-PH-TH/2022-35; CERN-TH-2022-089.-
2023-02-01 - 57 p.
- Published in : Phys. Rev. D 107 (2023) 035005
Fulltext: 2206.11676 - PDF; Publication - PDF;
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