13,087 research outputs found
Nuclear fusion induced by X-rays in a crystal
The nuclei that constitute a crystalline lattice, oscillate relative to each
other with a very low energy that is not sufficient to penetrate through the
Coulomb barriers separating them. An additional energy, which is needed to
tunnel through the barrier and fuse, can be supplied by external
electromagnetic waves (X-rays or the synchrotron radiation). Exposing to the
X-rays the solid compound LiD (lithium-deuteride) for the duration of 111
hours, we have detected 88 events of the nuclear fusion d+Li6 ---> Be8*. Our
theoretical estimate agrees with what we observed. One of possible applications
of the phenomenon we found, could be the measurements of the rates of various
nuclear reactions (not necessarily fusion) at extremely low energies
inaccessible in accelerator experiments.Comment: 27 pages, 12 figures; submitted to Phys. Rev. C on 28 October 201
Vector, Axial, Tensor and Pseudoscalar Vacuum Susceptibilities
Using a recently developed three-point formalism within the method of QCD Sum
Rules we determine the vacuum susceptibilities needed in the two-point
formalism for the coupling of axial, vector, tensor and pseudoscalar currents
to hadrons. All susceptibilities are determined by the space-time scale of
condensates, which is estimated from data for deep inelastic scattering on
nucleons
LHC Dark Matter Signals from Vector Resonances and Top Partners
Extensions of the Standard Model which address the hierarchy problem and dark
matter (DM) often contain top partners and additional resonances at the TeV
scale. We explore the phenomenology of a simplified effective model with a
vector resonance , a fermionic vector-like coloured partner of the top
quark as well as a scalar DM candidate and provide publicly
available implementations in CalcHEP and MadGraph. We study the process at the LHC and find that it
plays an important role in addition to the production via
strong interactions. It turns out that the presence of the can provide a
dominant contribution to the signature without
conflicting with existing bounds from searches in di-jet and di-lepton
final states. We find that through this process, the LHC is already probing DM
masses up to about 900 GeV and top partner masses up to about 1.5 TeV, thus
exceeding the current bounds from QCD production alone almost by a factor of
two for both particles.Comment: 32 pages, 15 figures, 3 table
Spontaneous violation of chiral symmetry in QCD vacuum is the origin of baryon masses and determines baryon magnetic moments and their other static properties
A short review is presented of the spontaneous violation of chiral symmetry
in QCD vacuum. It is demonstrated, that this phenomenon is the origin of baryon
masses in QCD. The value of nucleon mass is calculated as well as the masses of
hyperons and some baryonic resonances and expressed mainly through the values
of quark condensates -- -- the vacuum
expectation values (v.e.v.) of quark field. The concept of vacuum expectation
values induced by external fields is introduced. It is demonstrated that such
v.e.v. induced by static electromagnetic field results in quark condensate
magnetic susceptibility, which plays the main role in determination of baryon
magnetic moments. The magnetic moments of proton, neutron and hyperons are
calculated. The results of calculation of baryon octet -decay constants
are also presented.Comment: 13 pades, 5 figures. Dedicated to 85-birthday of acad. S.T.Belyaev.
To be published in Phys.At.Nucl. Few references are correcte
Microscopic description of -photoproduction on light nuclei
A microscopic four-body description of near-threshold coherent
photoproduction of the meson on the (3N)-nuclei is given. The
photoproduction cross-section is calculated using the Finite Rank Approximation
(FRA) of the nuclear Hamiltonian. The results indicate that the final state
interaction of the meson with the residual nucleus plays an important
role in the photoproduction process. Sensitivity of the results to the choice
of the T-matrix is investigated. The importance of obeying the
condition of unitarity is demonstrated.Comment: 4 pages, 4 figures; talk given at the International Conference on
Mesons and Light Nuclei '01, Prague, Czech Republic, July 2-6, 2001; to be
published in the Proceedings (AIP press
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