Measurement of ϒ production in pp collisions at √s = 2.76 TeV

The production of ϒ(1S), ϒ(2S) and ϒ(3S) mesons decaying into the dimuon final state is studied with the LHCb detector using a data sample corresponding to an integrated luminosity of 3.3 pb−1 collected in proton–proton collisions at a centre-of-mass energy of √s = 2.76 TeV. The differential production cross-sections times dimuon branching fractions are measured as functions of the ϒ transverse momentum and rapidity, over the ranges pT < 15 GeV/c and 2.0 < y < 4.5. The total cross-sections in this kinematic region, assuming unpolarised production, are measured to be σ (pp → ϒ(1S)X) × B ϒ(1S)→μ+μ− = 1.111 ± 0.043 ± 0.044 nb, σ (pp → ϒ(2S)X) × B ϒ(2S)→μ+μ− = 0.264 ± 0.023 ± 0.011 nb, σ (pp → ϒ(3S)X) × B ϒ(3S)→μ+μ− = 0.159 ± 0.020 ± 0.007 nb, where the first uncertainty is statistical and the second systematic

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

Jet shapes at HERA

The shape of jets produced in quasi-real photon-proton interactions and deep inelastic positron-proton scattering (DIS) at high Q(2) (Q(2) > 100 GeV2) has been measured with the ZEUS detector at HERA. Jets with transverse energies E-T(jet) > 14 GeV and pseudorapidities (eta(jet)) in the range -1 collisions, and are similar to those in e(+)e(-) interactions

Fragmentation functions at ZEUS

The scaled momentum spectra of final state charged hadrons produced in Deep Inelastic Scattering in the ranges 10 < Q(2) < 1280 GeV2 and 6 . 10(-4) < x(Bjorken) < 5 . 10(-2) have been measured in the current region of the Breit frame using the ZEUS detector. The evolution with Q(2) of the scaled momentum, x(p) = 2p(Breit)/Q, has been investigated and preliminary results are presented which show evidence for scaling violations and support for the universality of quark fragmentation

D* and J/psi inelastic photoproduction at HERA

Cross sections of D* and J/Psi inelastic photoproduction were measured by the ZEUS detector at HERA collider. Comparisons of the data with calculations in NLO pQCD and SHA QCD approaches were made