2014 Several inconsistencies contained in a paper (1969) by Van Vechten on interband energy calculation of covalent solids are discussed. In particular it is shown that energy gaps corresponding to E0, E1 and E2 can not be fitted to an expression of type Eg2 = Eh2 + C2, whether there is a d-core or not. LE JOURNAL DE PHYSIQUE TOME 35, FÉVRIER 1974,

Data from the H1 detector at HERA have been used to study photoproduction events which have two or more jets. The data were taken in 1996 and correspond to an integrated luminosity of 6.63 pb−1. Events were studied in the photon-proton centre of mass energy range 165 GeV < W < 243 GeV and with Q < 0.01 GeV. Jets were defined using the longitudinally invariant kt algorithm. Events selected had o...

Using angle-resolved photoemission spectroscopy, we report on the direct observation of the energy gap in 2H-NbSe2 caused by the charge-density waves (CDW). The gap opens in the regions of the momentum space connected by the CDW vectors, which implies a nesting mechanism of CDW formation. In remarkable analogy with the pseudogap in cuprates, the detected energy gap also exists in the normal sta...

We report singlet and triplet state splittings (I:J.EsT) for fluorine-substituted methylenes and silylenes using dissociation-consistent configuration interaction (CI) (based on generalized valence bond wave functions). These relatively simple CI calculations emphasize correlation consistency between the singlet and triplet states. Values of I:J.Esr for CH2, CF2, SiH2, and SiF2 are in excellent...

We study first-order mean-field quantum phase transitions, in particular the exponentially fast closure of the energy gap with the system size. We consider exactly solvable ferromagnetic models and discuss their relation to the Grover problem to which they reduce in a particular limit. We compute the coefficient in the exponential closure of the gap using an instantonic approach. We also discus...

We use perturbative QCD to calculate the parton level cross section for the production of two jets that are far apart in rapidity, subject to a limitation on the total transverse momentum Q0 in the interjet region. We specifically address the question of how to combine the approach which sums all leading logarithms in Q/Q0 (where Q is the jet transverse momentum) with the BFKL approach, in whic...

We used angle-resolved photoemission spectroscopy applied to deeply underdoped cuprate superconductors Bi2Sr2Ca(1-x)YxCu2O8 (Bi2212) to reveal the presence of two distinct energy gaps exhibiting different doping dependence. One gap, associated with the antinodal region where no coherent peak is observed, increased with underdoping, a behavior known for more than a decade and considered as the g...