Measurement of the charged-pion polarisability at COMPASS

The electric (${\alpha}_{\pi}$) and the magnetic (${\beta}_{\pi}$) polarisabilities are fundamental properties of the pion characterising the rigidity of its internal structure. They have been precisely measured at the COMPASS experiment at CERN with a ${\pi}^{-}$ beam of 190~GeV/c assuming ${\alpha}_{\pi}+{\beta}_{\pi}=0$. Muons of the same momentum were used for controlling of systematic effects. The obtained result ${\alpha}_{\pi}=-{\beta}_{\pi}=(2.0\pm 0.6_{stat.}\pm 0.7_{syst.})\times 10^{-4} fm^3$ is in agreement with the prediction of the Chiral Perturbation Theory.Comment: EPS-HEP-2015 proceeding

Search for muoproduction of the X(3872) at COMPASS

Exotic charmonium-like states have been observed by various experiments over the last 15 years, but their nature is still under discussion. Photo-(muo)production is a new promising instrument to study them. COMPASS, a fixed target experiment at CERN, analyzed the full set of the data collected with a muon beam between 2002 and 2011, covering the range from 7 GeV to 19 GeV in the centre-of-mass energy of the virtual photon-nucleon system. A signal in the mass spectrum of $J/\psi\pi^+\pi^-$ with the statistical significance of 4.1 $\sigma$ was observed in the reaction $\mu^+~N \rightarrow \mu^+(J/\psi\pi^+\pi^- )\pi^{\pm} N'$. Its mass and width are consistent with those of the $X(3872)$. The shape of the $\pi^+\pi^-$ mass distribution from the observed decay into $J/\psi\pi^+\pi^-$ is different from previous observations for $X(3872)$. The observed signal may be interpreted as possible evidence of a new charmonium state $\widetilde{X}(3872)$. It could be associated with a neutral partner of $X(3872)$ with $C = -1$ predicted by a tetraquark model.Comment: After the talk at the BEACH18 conference. arXiv admin note: text overlap with arXiv:1712.0134

SPD - the Spin Physics Project with Polarized Proton and Deuteron Beams at the NICA Collider

The SPD experiment at the future NICA collider at JINR (Dubna, Russia) aims to investigate the nucleon spin structure and polarization phenomena in collisions of longitudinally and transversely polarized protons and deuterons at $\sqrt{s}$ up to 27 GeV and luminosity up to 10$^{32}$ cm$^{-2}$ s$^{-1}$. Measurement of asymmetries in the Drell-Yan pairs, charmonium and prompt photon production can provide an access to the full set of leading twist TMD PDFs in nucleons. The experimental setup is planned as a universal 4$\pi$ detector for a wide range of physics tasks.Comment: QNP 2018 proceeding

On the possibility to use ATLAS and CMS detectors for neutrino physics

Energetic primary cosmic rays entering the Earth's atmosphere generate flux of secondary particles including neutrinos. Muon neutrinos passed through the Earth and produced muons via the charged current reaction can be registered by experimental setups intended for the measurements with colliding beams. Due to large geometrical size and advanced muon detecting system such detectors as ATLAS and CMS on LHC have chance to contribute also into the neutrino physics. The estimation of possible rates of up-going muons produced by neutrinos is given.Comment: 4 pages, 3 figure

Muoproduction of exotic charmonia at COMPASS

Exotic charmonium-like states have been targeted by various experiments in the last 15 years, but their nature still is unknown. Photo-(muo)production is a new promising instrument to study them. COMPASS, a fixed target experiment at CERN, analyzed the full set of the data collected with a muon beam between 2002 and 2011, covering the range from 7 GeV to 19 GeV in the centre-of-mass energy of the (virtual)photon-nucleon system. Production of the X(3872) state in the reaction $\mu^+~N \rightarrow \mu^+(J/\psi\pi^+\pi^- )\pi^{\pm} N'$ has been observed with a statistical significance of around 5 $\sigma$. The shape of the $\pi^+\pi^-$ mass distribution from the decay $X(3872)\rightarrow J/\psi\pi^+\pi^-$ shows disagreement with previous observations. The product of the cross section and the branching fraction of the $X(3872)$ decay into $J/\psi\pi\pi$ is estimated as 71$\pm$28(stat)$\pm$39(syst) pb. The results obtained for the production of the $Z_c^{\pm}(3900)$ are also reported as well as future perspectives.Comment: 4 pares 4 figure

SPD - the Spin Physics Project with Polarized Proton and Deuteron Beams at the NICA Collider

The SPD experiment at the future NICA collider at JINR (Dubna, Russia) aims to investigate the nucleon spin structure and polarization phenomena in collisions of longitudinally and transversely polarized protons and deuterons at $\sqrt{s}$ up to 27 GeV and luminosity up to 10$^{32}$ cm$^{-2}$ s$^{-1}$. Measurement of asymmetries in the Drell-Yan pairs, charmonium and prompt photon production can provide an access to the full set of leading twist TMD PDFs in nucleons. The experimental setup is planned as a universal 4$\pi$ detector for a wide range of physics tasks.Comment: QNP 2018 proceeding

Charmed hadron photoproduction at COMPASS

Photoproduction of the charmonium-like state $Z_{c}(4200)$ and the charmed baryon $\Lambda_{c}^{\ast }(2940)$ is investigated with an effective Lagrangian approach and the Regge trajectories applying to the COMPASS experiment. Combining the experimental data from COMPASS and our theoretical model we estimate the upper limit of $\Gamma_{Z_{c}(4200)\rightarrow J/\psi \pi }$ to be of about 37 MeV. Moreover, the possibility to produce $\Lambda_{c}^{\ast }(2940)$ at COMPASS is discussed. It seems one can try to search for this hadron in the missing mass spectrum since the $t$-channel is dominating for the $\Lambda_{c}^{\ast }(2940)$ photoproduction.Comment: Proceedings of the Second International Symposium on Physics of Photons (ISPP 15), Lanzhou, China, July 201

Reduced joint models for damping design of multi-jointed structures

− Design of damping in multi-jointed structures is studied here. − Dissipation sources are viscoelastic behavior and contact/friction at joints interfaces. − Reduction on meta-models of nonlinear joints models is investigated. − Experimental characterization of nonlinear forces

A General Bayesian Framework for Ellipse-based and Hyperbola-based Damage Localisation in Anisotropic Composite Plates

This paper focuses on Bayesian Lamb wave-based damage localization in structural health monitoring of anisotropic composite materials. A Bayesian framework is applied to take account for uncertainties from experimental time-of-flight measurements and angular dependent group velocity within the composite material. An original parametric analytical expression of the direction dependence of group velocity is proposed and validated numerically and experimentally for anisotropic composite and sandwich plates. This expression is incorporated into time-of-arrival (ToA: ellipse-based) and time-difference-of-arrival (TDoA: hyperbola-based) Bayesian damage localization algorithms. This way, the damage location as well as the group velocity profile are estimated jointly and a priori information taken into consideration. The proposed algorithm is general as it allows to take into account for uncertainties within a Bayesian framework, and to model effects of anisotropy on group velocity. Numerical and experimental results obtained with different damage sizes or locations and for different degrees of anisotropy validate the ability of the proposed algorithm to estimate both the damage location and the group velocity profile as well as the associated confidence intervals. Results highlight the need to consider for anisotropy in order to increase localization accuracy, and to use Bayesian analysis to quantify uncertainties in damage localization.Projet CORALI