Cluster structure of 13C probed via the 7Li(9Be,13C*->9Be+alpha) reaction

A study of the 7Li(9Be,4He9Be)3H reaction at E{beam}=70 MeV has been performed using resonant particle spectroscopy techniques and provides a measurement of alpha-decaying states in 13C. Excited states are observed at 12.0, 13.4, 14.1, 14.6, 15.2, 16.8, 17.9, 18.7, 21.3 and 23.9 MeV. This study provides the first measurement of the three highest energy states. Angular distribution measurements have been performed and have been employed to indicate the transferred angular momentum for the populated states. These data are compared with recent speculations of the presence of chain-like structures in 13C.Comment: accepted for publication in Nuclear Physics

alpha-decay of excited states in 11C and 11B

Studies of the 16O(9Be,alpha7Be)14C and 7Li(9Be,alpha7Li)5He reactions at E{beam}=70 MeV have been performed using resonant particle spectroscopy techniques. The 11C excited states decaying into alpha+7Be(gs) are observed at 8.65, 9.85, 10.7 and 12.1 MeV as well as possible states at 12.6 and 13.4 MeV. This result is the first observation of alpha-decay for excited states above 9 MeV. The alpha+7Li(gs) decay of 11B excited states at 9.2, 10.3, 10.55, 11.2, (11.4), 11.8, 12.5,(13.0), 13.1, (14.0), 14.35, (17.4) and (18.6) MeV is observed. The decay processes are used to indicate the possible three-centre 2alpha+3He(3H) cluster structure of observed states. Two rotational bands corresponding to very deformed structures are suggested for the positive-parity states. Excitations of some observed T=1/2 resonances coincide with the energies of T=3/2 states which are the isobaric analogs of the lowest 11Be states. Some of these states may have mixed isospin.Comment: accepted for publication in Nuclear Physics

Study of the lineshape of the chi(c1) (3872) state

A study of the lineshape of the chi(c1) (3872) state is made using a data sample corresponding to an integrated luminosity of 3 fb(-1) collected in pp collisions at center-of-mass energies of 7 and 8 TeV with the LHCb detector. Candidate chi(c1)(3872) and psi(2S) mesons from b-hadron decays are selected in the J/psi pi(+)pi(-) decay mode. Describing the lineshape with a Breit-Wigner function, the mass splitting between the chi(c1 )(3872) and psi(2S) states, Delta m, and the width of the chi(c1 )(3872) state, Gamma(Bw), are determined to be (Delta m=185.598 +/- 0.067 +/- 0.068 Mev,)(Gamma BW=1.39 +/- 0.24 +/- 0.10 Mev,) where the first uncertainty is statistical and the second systematic. Using a Flatte-inspired model, the mode and full width at half maximum of the lineshape are determined to be (mode=3871.69+0.00+0.05 MeV.)(FWHM=0.22-0.04+0.13+0.07+0.11-0.06-0.13 MeV, ) An investigation of the analytic structure of the Flatte amplitude reveals a pole structure, which is compatible with a quasibound D-0(D) over bar*(0) state but a quasivirtual state is still allowed at the level of 2 standard deviations

Measurement of the CKM angle γγ in B±→DK±B^\pm\to D K^\pm and B±→Dπ±B^\pm \to D π^\pm decays with D→KS0h+h−D \to K_\mathrm S^0 h^+ h^-

A measurement of $CP$-violating observables is performed using the decays $B^\pm\to D K^\pm$ and $B^\pm\to D \pi^\pm$, where the $D$ meson is reconstructed in one of the self-conjugate three-body final states $K_{\mathrm S}\pi^+\pi^-$ and $K_{\mathrm S}K^+K^-$ (commonly denoted $K_{\mathrm S} h^+h^-$). The decays are analysed in bins of the $D$-decay phase space, leading to a measurement that is independent of the modelling of the $D$-decay amplitude. The observables are interpreted in terms of the CKM angle $\gamma$. Using a data sample corresponding to an integrated luminosity of $9\,\text{fb}^{-1}$ collected in proton-proton collisions at centre-of-mass energies of $7$, $8$, and $13\,\text{TeV}$ with the LHCb experiment, $\gamma$ is measured to be $\left(68.7^{+5.2}_{-5.1}\right)^\circ$. The hadronic parameters $r_B^{DK}$, $r_B^{D\pi}$, $\delta_B^{DK}$, and $\delta_B^{D\pi}$, which are the ratios and strong-phase differences of the suppressed and favoured $B^\pm$ decays, are also reported

Study of the doubly charmed tetraquark T+cc

Quantum chromodynamics, the theory of the strong force, describes interactions of coloured quarks and gluons and the formation of hadronic matter. Conventional hadronic matter consists of baryons and mesons made of three quarks and quark-antiquark pairs, respectively. Particles with an alternative quark content are known as exotic states. Here a study is reported of an exotic narrow state in the D0D0π+ mass spectrum just below the D*+D0 mass threshold produced in proton-proton collisions collected with the LHCb detector at the Large Hadron Collider. The state is consistent with the ground isoscalar T+cc tetraquark with a quark content of ccu⎯⎯⎯d⎯⎯⎯ and spin-parity quantum numbers JP = 1+. Study of the DD mass spectra disfavours interpretation of the resonance as the isovector state. The decay structure via intermediate off-shell D*+ mesons is consistent with the observed D0π+ mass distribution. To analyse the mass of the resonance and its coupling to the D*D system, a dedicated model is developed under the assumption of an isoscalar axial-vector T+cc state decaying to the D*D channel. Using this model, resonance parameters including the pole position, scattering length, effective range and compositeness are determined to reveal important information about the nature of the T+cc state. In addition, an unexpected dependence of the production rate on track multiplicity is observed

The 14UD pelletron accelerator

The 14UD has evolved over the past two years from acceptance tests to an extremely reliable and convenient research tool well suited to heavy-ion physics research. The development of the open corona point distribution system with the reintroduction of tie wires eliminated problems with gradient control and point lifetime. Easy inspection of the open points is a valuable diagnostic aid when beam transport problems occur. Electromechanical remote actuators for functions in the terminal have been replaced with pneumatic ones driven by SF 6 at 50 psi above tank pressure. Foils are changed, sublimer pellet heaters switched and a high energy tube entrance aperture selected by these devices. Long experience running from 6 to 13 MV has convinced us that enclosed corona points would not make our operation any more convenient. The machine is quite stable with negligible tube and column corona currents. Because of this, the machine typically runs with only one chain at a time. Since installation of SF6 powered oilers for the chains, there have been no further problems of instability or breakage. An integral valve for the NEC stripper foil assembly has been installed to maintain the conditioned status of the tube during stripper foil changes. All main power wiring has been replaced with mineral insulated cable sheathed in copper. No degradation in insulation has been found.Le 14UD a évolué au cours des deux dernières années, des essais de réception vers un outil de recherche très convenable et bien adapté à la physique des ions lourds ont été faits. Le développement du système de répartition à pointe corona ouverte avec la réintroduction de fils liés a éliminé les problèmes liés au contrôle des gradiens et à la durée de vie des pointes corona. L'inspection commode des pointes ouvertes est d'une aide efficace pour établir un diagnostic lors de problèmes de transport de faisceau. Les commandes à distance électromécaniques dans le terminal ont été remplacées par des commandes pneumatiques activées par du SF 6 à une pression de 50 psi au-dessus de la pression du tank. Les feuilles sont changées, les sublimateurs mis en route et le diaphragme d'ouverture du tube haute énergie sélectionné à l'aide de ces dispositifs. Une longue expérience de conduite entre 6 et 13 MV nous a convaincu que les pointes corona fermées n'étaient pas convenables pour notre opération. La machine est très stable avec des courants corona négligeables sur le tube ou sur la colonne. A cause de cela la machine ne fonctionne typiquement qu'avec une seule chaîne en service à la fois. Depuis l'installation de graisseurs activés au SF 6 pour les chaînes, il n'y a eu aucun autre problème d'instabilité ou de décharge. Une vanne intégrée pour le système de feuilles de stripper NEC a été installée afin de maintenir le tube en état de conditionnement lors du changement de feuilles. Tous les câbles d'alimentation de puissance ont été remplacés par des câbles isolés de matière minérale. Aucune dégradation de l'isolement n'a été observée