15,413,441 research outputs found

    Classification of States in O(8) Proton-Neutron Pairing Model

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    Isoscalar (T=0) plus isovector (T=1) pairing hamiltonian in LS-coupling, which is important for heavy N=Z nuclei, is solvable in terms of a O(8) algebra for some special values of the mixing parameter that measures the competition between T=0 and T=1 pairing. The O(8) algebra is generated, amongst others, by the S=1,T=0S=1,T=0 and S=0,T=1S=0,T=1 pair creation and annihilation operators . Shell model algebras, with only number conserving operators, that are complementary to the O(8)OST(6)OS(3)OT(3)O(8) \supset O_{ST}(6) \supset O_S(3) \otimes O_T(3), O(8)[OS(5)OS(3)]OT(3)O(8) \supset [ O_S(5) \supset O_S(3) ] \otimes O_T(3) and O(8)[OT(5)OT(3)]OS(3)O(8) \supset [ O_T(5) \supset O_T(3)] \otimes O_S(3) sub-algebras are identified. The problem of classification of states for a given number of nucleons (called `plethysm' problem in group theory), for these group chains is solved explicitly for states with O(8) seniority v=0,1,2,3v=0, 1, 2, 3 and 4. Using them, band structures in isospin space are identified for states with v=0,1,2v=0, 1, 2 and 3.Comment: 52 pages, 12 table

    Pressure-induced enhancement of superconductivity and superconducting-superconducting transition in CaC_6\_6

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    We measured the electrical resistivity, ϱ(T)\varrho(T), of superconducting CaC_6\_6 at ambient and high pressure up to 16 GPa. For PP \leq8 GPa, we found a large increase of T_cT\_c with pressure from 11.5 up to 15.1 K. At 8 GPa, T_cT\_c drops and levels off at 5 K above 10 GPa. Correspondingly, the residual ϱ\varrho increases by \approx 200 times and the ϱ(T)\varrho(T) behavior becomes flat. The recovery of the pristine behavior after depressurization is suggestive of a phase transition at 8 GPa between two superconducting phases with good and bad metallic properties, the latter with a lower T_cT\_c and more static disorder

    II. Detection of an antigen on resting T cells down-regulated after activation

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    The expression of an antigen on porcine T lymphocytes detected by murine monoclonal antibody (mAb) 8/1 was investigated by functional studies and dual-parameter immunofluorescence. mAb 8/1 reacts with greater than 95% of thymocytes and in peripheral blood with all T lymphocytes and with cells of the monocyte/macrophage lineage, but not with B cells, erythrocytes, and platelets. Pretreatment of peripheral blood lymphocytes with mAb 8/1 plus complement abrogated the proliferative response in vitro to mitogen, soluble antigen, and MHC determinants. Dual-parameter immunofluorescence revealed that resting porcine T8+ as well as T4+ lymphocytes express the 8/1 antigen, whereas after in vitro activation, cell surface expression of the antigen was low or absent in both T cell subsets. Thus, the 8/1 antigen represents a marker that discriminates between resting and activated T lymphocytes. Distribution and functional criteria indicate that 8/1 represents a novel marker not described before for any other mammalian species

    Towards the fate of natural composite Higgs model through single tt^\prime search at the 8 TeV LHC

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    We analyze the observational potential of single tt' production in both the tbWt^\prime \rightarrow bW and ttht^\prime \rightarrow th decay channels at 8 TeV LHC using an integrated luminosity of 25 fb1\text{fb}^{-1}. Our analysis is based on a simplified model with minimal coset SO(5)/SO(4)SO(5)/SO(4) in which the tt' is a singlet of the unbroken SO(4). The single tt' production, as a consequence of electroweak symmetry breaking, is less kinematically suppressed, associated with a light forward jet and has boosted decay products at the 8 TeV LHC. Therefore it provides the most promising channel in searching for a heavy tt'. We have exploited the above kinematical features and used the jet substructure method to reconstruct the boosted Higgs in thth decay channel. It is shown that a strong constraint on the tbWt^\prime bW coupling (gtbW/gtbW,SM<0.20.3g_{t^\prime bW}/g_{tbW,SM} < 0.2 \sim 0.3) at the 95% C. L. can be obtained for mt(700,1000)m_{t'} \subset (700, 1000) GeV.Comment: 22 pages, 8 figures, 5 tables, refs added in v

    Domain walls in three dimensional gauged supergravity

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    We explicitly construct two Chern-Simons gauged supergravities in three dimensions with N=4 and N=8 supersymmetries and non-semisimple gauge groups. The N=4 theory has scalar manifold SO(4,3)/SO(4)×SO(3)SO(4,3)/SO(4)\times SO(3) with the gauge group SO(3)(T3,T^3)SO(3)\ltimes (\mathbf{T}^3,\hat{\mathbf{T}}^3). The theory describes (1,0) six dimensional supergravity reduced on an SU(2) group manifold. The equivalent Yang-Mills type gauged supergravity has SO(3) gauge group coupled to three massive vector fields. The N=8 theory is described by SO(8,8)/SO(8)×SO(8)SO(8,8)/SO(8)\times SO(8) scalar manifold, and the gauge group is given by SO(8)T28SO(8)\ltimes \mathbf{T}^{28}. The theory is a truncation of the SO(8)T28SO(8)\ltimes \mathbf{T}^{28} gauged N=16 theory with scalar manifold E8(8)/SO(16)E_{8(8)}/SO(16) and can be obtained by an S^7 compactification of type I theory in ten dimensions. Domain wall solutions of both gauged supergravities are analytically found and can be uplifted to higher dimensions. These provide domain wall vacua in the three dimensional gauged supergravity framework which might be useful for the study of Domain Wall3_3/QFT2_2 correspondence.Comment: 19 pages, no figures, typoes and a mistake in a sign corrected, clarifications on the notations adde
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