150,195 research outputs found
The nuclear electric polarizability of 6He
We present an estimate of the nuclear electric polarizability of the 6He halo
nucleus based on six-body microscopic calculations. Wave functions are obtained
from semi-realistic two-body interactions using the hyperspherical harmonics
expansion method. The polarizability is calculated as a sum rule of the dipole
response function using the Lanczos algorithm and also by integrating the
photo-absorption cross section calculated via the Lorentz integral transform
method. We obtain alpha_E=1.00(14) fm^3, which is much smaller than the
published value 1.99(40) fm^3 extracted from experimental data. This points
towards a potential disagreement between microscopic theories and experimental
observations.Comment: 8 pages, 8 figures, minor changes, added error analysi
Probes for 4th generation constituents of dark atoms in Higgs boson studies at the LHC
The nonbaryonic dark matter of the Universe can consist of new stable charged
species, bound in heavy neutral "atoms" by ordinary Coulomb interaction. Stable
(anti-)quarks of 4th generation, bound in stable colorless () clusters, are captured by the primordial helium, produced in
Big Bang Nucleosynthesis, thus forming neutral "atoms" of O-helium (OHe), a
specific nuclear interacting dark matter that can provide solution for the
puzzles of direct dark matter searches. However, the existence of the 4th
generation quarks and leptons should influence the production and decay rates
of Higgs boson and is ruled out by the experimental results of the Higgs boson
searches at the LHC, if the Higgs boson coupling to 4th generation fermions
with is not suppressed. Here we argue that the difference between the three
known quark-lepton families and the 4th family can naturally lead to
suppression of this coupling, relating the accelerator test for such a
composite dark matter scenario to the detailed study of the production and
modes of decay of the 125.5 GeV boson, discovered at the LHC.Comment: Prepared for the Special issue "Dark atoms and dark radiation" of
Advances in High Energy Physic
Correlation femtoscopy of small systems
The basic principles of the correlation femtoscopy, including its
correspondence to the Hanbury Brown and Twiss intensity interferometry, are
re-examined. The main subject of the paper is an analysis of the correlation
femtoscopy when the source size is as small as the order of the uncertainty
limit. It is about 1 fm for the current high energy experiments. Then the
standard femtoscopy model of random sources is inapplicable. The uncertainty
principle leads to the partial indistinguishability and coherence of closely
located emitters that affect the observed femtoscopy scales. In thermal systems
the role of corresponding coherent length is taken by the thermal de Broglie
wavelength that also defines the size of a single emitter. The formalism of
partially coherent phases in the amplitudes of closely located individual
emitters is used for the quantitative analysis. The general approach is
illustrated analytically for the case of the Gaussian approximation for
emitting sources. A reduction of the interferometry radii and a suppression of
the Bose-Einstein correlation functions for small sources due to the
uncertainty principle are found. There is a positive correlation between the
source size and the intercept of the correlation function. The peculiarities of
the non-femtoscopic correlations caused by minijets and fluctuations of the
initial states of the systems formed in and collisions are also
analyzed. The factorization property for the contributions of femtoscopic and
non-femtoscopic correlations into complete correlation function is observed in
numerical calculations in a wide range of the model parameters.Comment: 34 pages, 5 figures. In the version 4 some stylistic improvements
were made, some misprints were corrected. The results and conclusions are not
change
Generalized Yang-Baxter Equation
A generalization of the Yang-Baxter equation is proposed. It enables to
construct integrable two-dimensional lattice models with commuting two-layer
transfer matrices, while single-layer ones are not necessarily commutative.
Explicit solutions to the generalized equations are found. They are related
with Botzmann weights of the chiral Potts model.Comment: 13 pages, TeX file. IHEP-93-?
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