For a large class of finite-range quantum spin models with half-integer spins, we prove that uniqueness of the ground state implies the existence of a low-lying excited state. For systems of linear size L, of arbitrary finite dimension, we obtain an upper bound on the excitation energy (i.e., the gap above the ground state) of the form (C log L)/L. This result can be regarded as a multi-dimensi...

Heavy flavour production and spectroscopy are key components of the HERA physics programme. I will summarise a selection of the recent results obtained by the H1 and ZEUS collaborations. The production of excited charm mesons and J/ψ will be discussed as well as measurements of b quark cross-sections in photoproduction. The status of searches for exotic bound states and the D∗p resonance will b...

The D dimensional quasi exact solutions for the singular even power anharmonic potential V (q) = aq2 + bq−4 + cq−6 are reported. We show that whilst Dong and Ma’s [5] quasi exact ground state solution (in D=2) is beyond doubt, their solution for the first excited state is exotic. Quasi exact solutions for the ground and first excited states are also given for the above potential confined to an ...

The crystal structures of two modifications of 4,49-dihydroxybenzophenone with 4,13-diaza-18-crown-6 have been analyzed in terms of their suitability for time-resolved diffraction studies of transient excited species in crystals. The room-temperature lifetimes of the triplet excited state of the dihydroxybenzophenone molecule in the two modifications have been determined as 44.2 6 1.2 ms and 49...

The D dimensional quasi exact solutions for the singular even power anharmonic potential V (q) = aq2 + bq−4 + cq−6 are reported. We show that whilst Dong and Ma’s [5] quasi exact ground state solution (in D=2) is beyond doubt, their solution for the first excited state is exotic. Quasi exact solutions for the ground and first excited states are also given for the above potential confined to an ...

We present results for the ground state and first excited state static potentials in the confinement " phase " of the SU(2) Higgs model. String breaking and the crossing of the energy levels are clearly visible. We address the question of the cutoff effects in our results and observe a remarkable scaling of the static potentials.

Angular distrihutions of the ‘rC(d, 6Li)8Be reaction at i& = 78.0 MeVand the 1’B(3He, ‘Li)*Be reaction at E,,, = 71.8 MeV were measured. Transitions leading to ‘Be in the ground state and the 3.04, 16.63, 16.92, 17.64 and 18.15 MeV excited states were observed. A DWBA analysis was performed regarding the (d, 6Li) and (3He, 6Li) reactions as direct LY particle or triton transfers, respectively. ...

The WKB and instanton answers for the tunnel splitting of the ground state in a symmetric double well potential are both reduced to an expression involving only the functionals of the potential, without the need for solving any auxilliary problems. This formula is applied to simple model problems. The prefactor for the splitting in the text book by Landau and Lifshitz is amended so as to apply ...