14,643 research outputs found
Exclusive quasielastic production of dijets at hadronic colliders
We critically re-examine the calculation of central production of dijets in
quasi-elastic hadronic collisions. We find that the process is not dominated by
the perturbative contribution, and discuss several sources of uncertainties in
the calculation.Comment: 4 pages, talk given at Diffraction-2008, La Londe-les-Maures, France,
9-14 Sept 200
Enhancement of magnetic ordering by the stress fields of grain boundaries in ferromagnets
In the paper we predict a distinctive change of magnetic properties and
considerable increase of the Curie temperature caused by the strain fields of
grain boundaries in ferromagnetic films. It is shown that a sheet of
spontaneous magnetization may arise along a grain boundary at temperatures
greater than the bulk Curie temperature. The temperature dependence and space
distribution of magnetization in a ferromagnetic film with grain boundaries are
calculated. We found that grain boundaries can produce long-range
strain fields that results in the width of the magnetic sheet along the
boundary of the order of at temperatures grater than the
bulk Curie temperature by about K.Comment: 5 pages, 3 Figures include
Radiative corrections of order O(alpha E_e/m_N) to Sirlin's radiative corrections of order O(alpha/pi) to neutron lifetime
We calculate the radiative corrections of order O(alpha E_e/m_N) as
next-to-leading order corrections in the large nucleon mass expansion to
Sirlin's radiative corrections of order O(alpha/pi) to the neutron lifetime.
The calculation is carried out within a quantum field theoretic model of strong
low-energy pion--nucleon interactions described by the linear sigma-model (LsM)
with chiral SU(2)xSU(2) symmetry and electroweak hadron-hadron, hadron-lepton
and lepton-lepton interactions for the electron-lepton family with SU(2)_L x
U(1)_Y symmetry of the Standard Electroweak Model (SEM). Such a quantum field
theoretic model is some kind a hadronized version of the Standard Model (SM).
From a gauge invariant set of the Feynman diagrams with one-photon exchanges we
reproduce Sirlin's radiative corrections of order O(alpha/pi), calculated to
leading order in the large nucleon mass expansion, and calculate
next-to-leading corrections of order O(alpha E_e/m_N). This confirms Sirlin's
confidence level of the radiative corrections O(alpha E_e/m_N). The
contributions of the LsM are taken in the limit of the infinite mass of the
scalar isoscalar sigma-meson. In such a limit the LsM reproduces the results of
the current algebra (Weinberg, Phys. Rev. Lett. {\bf 18}, 188 (1967)) in the
form of effective chiral Lagrangians of pion-nucleon interactions with
non--linear realization of chiral SU(2)xSU(2) symmetry. In such a limit the
LM is also equivalent to Gasser-Leutwyler's chiral quantum field theory
or chiral perturbation theory (ChPT) with chiral SU(2)xSU(2)symmetry and the
exponential parametrization of a pion-field (Ecker, Prog. Part. Nucl. Phys.
{\bf 35}, 1 (1995)).Comment: 50 pages, 7 figures. arXiv admin note: text overlap with
arXiv:1805.0970
Electrodisintegration of Deuteron into Dark Matter and Proton Close to Threshold
We discuss an investigation of the dark matter decay modes of the neutron,
proposed by Fornal and Grinstein (Phys. Rev. Lett. 120 191801 (2018)) and
Ivanov et al. ( arXiv:1806.10107 [hep-ph]) for solution of the neutron lifetime
anomaly problem, through the analysis of the electrodisintegration of the
deuteron d into dark matter fermions chi and protons p close to threshold. We
calculate the triple-differential cross section for the reaction e^- + d ->\chi
+ p + e^- and propose to search for such a dark matter channel in coincidence
experiments on the electrodisintegration of the deuteron e^- + d -> n + p + e^-
into neutrons n and protons close to threshold with outgoing electrons, protons
and neutrons in coincidence. A missing of neutron signals should testify a
detection of dark matter fermions.Comment: 7 pages, 1 figure, the paper is revised, according to a revision of
1806.10107v2 [hep-ph
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