66 research outputs found
Anisotropic admixture in color-superconducting quark matter
The analysis of color-superconducting two-flavor deconfined quark matter at
moderate densities is extended to include a particular spin-1 Cooper pairing of
those quarks which do not participate in the standard spin-0 diquark
condensate. (i) The relativistic spin-1 gap Delta' implies spontaneous
breakdown of rotation invariance manifested in the form of the quasi-fermion
dispersion law. (ii) The critical temperature of the anisotropic component is
approximately given by the relation T_c'~ Delta'(T=0)/3. (iii) For massless
fermions the gas of anisotropic Bogolyubov-Valatin quasiquarks becomes
effectively gapless and two-dimensional. Consequently, its specific heat
depends quadratically on temperature. (iv) All collective Nambu-Goldstone
excitations of the anisotropic phase have a linear dispersion law and the whole
system remains a superfluid. (v) The system exhibits an electromagnetic
Meissner effect.Comment: v2: references added, angular dependence of the gap clarified, v3:
extended discussion, typo in eq. (5) corrected, version accepted for
publication in PR
Dynamical electroweak symmetry breaking due to strong Yukawa interactions
We present a new mechanism for electroweak symmetry breaking (EWSB) based on
a strong Yukawa dynamics. We consider an SU(2)_L x U(1)_Y gauge invariant model
endowed with the usual Standard model fermion multiplets and with two massive
scalar doublets. We show that, unlike in the Standard model, EWSB is possible
even with vanishing vacuum expectation values of the scalars. Such EWSB is
achieved dynamically by means of the (presumably strong) Yukawa couplings and
manifests itself by the emergence of fermion and gauge boson masses and scalar
mass-splittings, which are expressed in a closed form in terms of the fermion
and scalar proper self-energies. The `would-be' Nambu--Goldstone bosons are
shown to be composites of both the fermions and the scalars. We demonstrate
that the simplest version of the model is compatible with basic experimental
constraints.Comment: 6 pages, REVTeX4, 3 eps figures; discussion of compatibility with EW
precision data added; version published in J. Phys.
Summary of OSQAR First Achievements and Main Requests for 2008
Abstract - In the first paragraph, OSQAR foremost achievements are summarised together with a brief reminder of its scientific context. In the second paragraph, activities planned for 2008 are briefly reviewed including the expected scientific results. The third paragraph is devoted to the requests addressed to CERN as the host laboratory and as a collaboration member of the OSQAR photon regeneration experiment
The Shaqadud Archaeological Project (Sudan): exploring prehistoric cultural adaptations in the Sahelian hinterlands
The authors present preliminary results from a new research project based in Jebel Shaqadud, Sudan. Their findings highlight the potential for this region's archaeological record to expand our understanding of the adaptation strategies used by human groups in arid north-east African environments away from rivers and lakes during the Holocene. Furthermore, they present exceptionally early radiocarbon dates that push postglacial human occupation in the eastern Sahel back to the twelfth millennium BP
Weak axial nuclear heavy meson exchange currents and interactions of solar neutrinos with deuterons
Starting from the axial heavy meson exchange currents, constructed earlier in
conjunction with the Bethe--Salpeter equation, we first present the axial
--, -- and meson exchange Feynman amplitudes that satisfy
the partial conservation of the axial current. Employing these amplitudes, we
derive the corresponding weak axial heavy meson exchange currents in the
leading order in the 1/M expansion ( is the nucleon mass), suitable for the
nuclear physics calculations beyond the threshold energies and with wave
functions obtained by solving the Schr\"odinger equation with one--boson
exchange potentials. The constructed currents obey the nuclear form of the
partial conservation of the axial current. We apply the space component of
these currents in calculations of the cross sections for the disintegration of
deuterons by low energy (anti)neutrinos. The deuteron and the final state
nucleon--nucleon wave functions are derived (i) from a variant of the OBEPQB
potential, and (ii) from the Nijmegen 93 and Nijmegen I nucleon-nucleon
interaction. The extracted values of the constant , entering the
axial exchange currents of the pionless effective field theory, are in a
reasonable agreement with its value predicted by the dimensional analysis.Comment: 34 pages, 3 figures, 11 table
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