445 research outputs found
Reply to "Comment on 'Isotope effect in multi-band and multi-channel attractive systems and inverse isotope effect in iron-based superconductors'"
The Comment insists on the following: in our model it is assumed that the
effective interactions have specific energy ranges within the single band with
a cutoff at \omega_1 for the phononic part and a range from \omega_1 to
\omega_2 in the AF channel. Our reply is that we assume that V_i(k,k')\neq 0 if
|\xi_k|<\omega_i and |\xi_{k'}|<\omega_i, and otherwise V_i(k,k')= 0 (i=1,2),
as stated in our paper. This is the model of BCS type with two attractive
interactions, and this assumption is the characteristic of the BCS
approximation. The claim "the integration limits have been modified such that
the AF channel mediated pairing sets in where the ph-channel pairing terminates
and is limited at an energy given by \omega_j=\omega_{AF}" in the Comment is
wrong. We describe the model and the method to solve the gap equation in more
detail
Pair production of charged Higgs scalars from electroweak gauge boson fusion
We compute the contribution to charged Higgs boson pair production at the
Large Hadron Collider (LHC) due to the scattering of two electroweak (EW) gauge
bosons, these being in turn generated via bremsstrahlung off incoming quarks: q
q --> q q V^*V^* --> q q H^+H^- (V=gamma,Z,W^{+/-}). We verify that the
production cross section of this mode is tan beta independent and show that it
is smaller than that of H^+H^- production via q q-initiated processes but
generally larger than that of the loop-induced channel gg --> H^+H^-. Pair
production of charged Higgs bosons is crucial in order to test EW symmetry
breaking scenarios beyond the Standard Model (SM). We show that the detection
of these kind of processes at the standard LHC is however problematic, because
of their poor production rates and the large backgrounds.Comment: 22 pages, latex, 8 figures (largely revised version to appear in JPG
Flavour structure of low-energy hadron pair photoproduction
We consider the process where and
are either mesons or baryons. The experimental findings for such quantities as
the and differential cross sections, in the energy range
currently probed, are found often to be in disparity with the scaling behaviour
expected from hard constituent scattering. We discuss the long-distance
pole--resonance contribution in understanding the origin of these phenomena, as
well as the amplitude relations governing the short-distance contribution which
we model as a scaling contribution. When considering the latter, we argue that
the difference found for the and the integrated cross
sections can be attributed to the s-channel isovector component. This
corresponds to the subprocess in the VMD
(vector-meson-dominance) language. The ratio of the two cross sections is
enhanced by the suppression of the component, and is hence constrained.
We give similar constraints to a number of other hadron pair production
channels. After writing down the scaling and pole--resonance contributions
accordingly, the direct summation of the two contributions is found to
reproduce some salient features of the and data.Comment: 12 pages, 9 figures, revised version to be published in EPJ
Next-to-Leading order Higgs + 2 jet production via gluon fusion
We present phenomenological results for the production of a Higgs boson in
association with two jets at the LHC. The calculation is performed in the limit
of large top mass and is accurate to next-to-leading order in the strong
coupling, i.e. Comment: 13 pages, 6 figures; v2: references added, modified acknowledgments,
final version as published in JHE
Dissociative photoionization of the NO molecule studied by photoelectron-photon coincidence technique
Low-energy photoelectronâvacuum ultraviolet (VUV) photon coincidences have been measured using synchrotron radiation excitation in the inner-valence region of the nitric oxide molecule. The capabilities of the coincidence set-up were demonstrated by detecting the 2sâ1 â 2pâ1 radiative transitions in coincidence with the 2s photoelectron emission in Ne. In NO, the observed coincidence events are attributed to dissociative photoionization with excitation, whereby photoelectron emission is followed by fragmentation of excited NO+ ions into O+ + N* or N+ + O* and VUV emission from an excited neutral fragment. The highest coincidence rate occurs with the opening of ionization channels which are due to correlation satellites of the 3Ï photoionization. The decay time of VUV photon emission was also measured, implying that specific excited states of N atoms contribute significantly to observed VUV emission
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