11,001 research outputs found

    Nuclear Schiff moment and soft vibrational modes

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    The atomic electric dipole moment (EDM) currently searched by a number of experimental groups requires that both parity and time-reversal invariance be violated. According to current theoretical understanding, the EDM is induced by the nuclear Schiff moment. The enhancement of the Schiff moment by the combination of static quadrupole and octupole deformation was predicted earlier. Here we study a further idea of the possible enhancement in the absence of static deformation but in a nuclear system with soft collective vibrations of two types. Both analytical approximation and numerical solution of the simplified problem confirm the presence of the enhancement. We discuss related aspects of nuclear structure which should be studied beyond mean-field and random phase approximations.Comment: 14 pages, 4 figure

    Gauge invariant effective action for the Polyakov line in the SU(N) Yang--Mills theory at high temperatures

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    We integrate out fast varying quantum fluctuations around static A_4 and A_i fields for the SU(N) gauge group. By assuming that the gluon fields are slowly varying but allowing for an arbitrary amplitude of A_4 we obtain two variants of the effective high-temperature theory for the Polyakov line. One is the effective action for the gauge-invariant eigenvalues of the Polyakov line, and it is explicitly Z(N) symmetric. The other is the effective action for the Polyakov line itself as an element of the SU(N). In this case the theory necessarily includes the spatial components A_i to ensure its gauge invariance under spatial gauge transformations. We derive the 1-loop effective action in the `electric' and `magnetic' sectors, summing up all powers of A_4.Comment: RevTex4, 2 figure

    Nuclear Schiff moment in nuclei with soft octupole and quadrupole vibrations

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    Nuclear forces violating parity and time reversal invariance (P,T{\cal P},{\cal T}-odd) produce P,T{\cal P},{\cal T}-odd nuclear moments, for example, the nuclear Schiff moment. In turn, this moment can induce the electric dipole moment in the atom. The nuclear Schiff moment is predicted to be enhanced in nuclei with static quadrupole and octupole deformation. The analogous suggestion of the enhanced contribution to the Schiff moment from the soft collective quadrupole and octupole vibrations in spherical nuclei is tested in this article in the framework of the quasiparticle random phase approximation with separable quadrupole and octupole forces applied to the odd 217221^{217-221}Ra and 217221^{217-221}Rn isotopes. We confirm the existence of the enhancement effect due to the soft modes. However, in the standard approximation the enhancement is strongly reduced by a small weight of the corresponding "particle + phonon" component in a complicated wave function of a soft nucleus. The perspectives of a better description of the structure of heavy soft nuclei are discussed.Comment: 27 pages, 3 figures, minor corrections in references adde

    Perturbative QCD Correction to the Light-Cone Sum Rule for the BBπB^*B\pi and DDπD^*D\pi Couplings

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    The BBπB^*B\pi and DDπD^*D\pi couplings have previously been derived from a QCD light-cone sum rule in leading order. Here, we describe the calculation of the O(αs)O(\alpha_s) correction to the twist 2 term of this sum rule. The result is used for a first next-to-leading order analysis. We obtain gBBπ=22±7g_{B^*B\pi}= 22\pm 7 and gDDπ=10.5±3g_{D^*D\pi}=10.5\pm 3, where the error indicates the remaining theoretical uncertainty.Comment: 11 pages, 1 figure, Latex, epsfi

    Potential energy and dipole moment surfaces of H3- molecule

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    A new potential energy surface for the electronic ground state of the simplest triatomic anion H3- is determined for a large number of geometries. Its accuracy is improved at short and large distances compared to previous studies. The permanent dipole moment surface of the state is also computed for the first time. Nine vibrational levels of H3- and fourteen levels of D3- are obtained, bound by at most ~70 cm^{-1} and ~ 126 cm^{-1} respectively. These results should guide the spectroscopic search of the H3- ion in cold gases (below 100K) of molecular hydrogen in the presence of H3- ions

    Supersymmetric Higgs pair discovery prospects at hadron colliders

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    We study the potential of hadron colliders in the search for the pair production of neutral Higgs bosons in the framework of the Minimal Supersymmetric Standard Model. Using analytical expressions for the relevant amplitudes, we perform a detailed signal and background analysis, working out efficient kinematical cuts for the extraction of the signal. The important role of squark loop contributions to the signal is emphasised. If the signal is sufficiently enhanced by these contributions, it could even be observable at the next run of the upgraded Tevatron collider in the near future. At the LHC the pair production of light and heavy Higgs bosons might be detectable simultaneously.Comment: 5 pages, hep99, 6 figures; Presented at the International Europhysics Conference on High Energy Physics, Tampere, Finland, 15-21 July 199

    Deconfinement in Matrix Models about the Gross--Witten Point

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    We study the deconfining phase transition in SU(N) gauge theories at nonzero temperature using a matrix model of Polyakov loops. The most general effective action, including all terms up to two spatial derivatives, is presented. At large N, the action is dominated by the loop potential: following Aharony et al., we show how the Gross--Witten model represents an ultra-critical point in this potential. Although masses vanish at the Gross--Witten point, the transition is of first order, as the fundamental loop jumps only halfway to its perturbative value. Comparing numerical analysis of the N=3 matrix model to lattice simulations, for three colors the deconfining transition appears to be near the Gross--Witten point. To see if this persists for N >= 4, we suggest measuring within a window ~1/N^2 of the transition temperature.Comment: 22 pages, 7 figures; revtex4. A new Fig. 2 illustrates a strongly first order transition away from the GW point; discussion added to clarify relation to hep-th/0310285. Conclusions include a discussion of recent lattice data for N>3, hep-lat/0411039 and hep-lat/050200

    PETROGRAPHY AND MINERALOGY OF RETROGRADE METAPERIDOTITES FROM ALAG KHADNY ACCRETIONARY WEDGE (SW MONGOLIA): FLUID MODIFICATION IN SUPRASUBDUCTION ZONE

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    The Main Mongolian Lineament (MML) separates northern “Caledonian” tectonic province from southern “Hercynian” in SW part of Mongolia of the Central Asian Orogenic Belt (CAOB). The position of Eastern part of MML is widely discussed at recent time, since, this is an important for reconstruction of geodynamic evolution of this region. Some researchers suggest that ophiolite from the Erdene Uul and Maykhan Tsakhir Uul mountain ranges are Eastern part of an ophiolitic nappe system thrust northwards over the Dzabkhan-Baydrag continent, namely the Khantaishir and the Dariv ophiolites [Štípská et al., 2010; Buriánek et al., 2017]. Others have a different view, they suggest that investigated ophiolites refers to Gobi-Altai ophiolite system (523±5 – 518±6 Ma), which likely formed in front of the Gobi Altai microcontinent by initiation of a new southdipping subduction zone following arc–microcontinent collision in Northwest Mongolia [Jian et al., 2014]. However, ophiolites of this critical region of Mongolian the CAOB have not been investigated in detail.The Main Mongolian Lineament (MML) separates northern “Caledonian” tectonic province from southern “Hercynian” in SW part of Mongolia of the Central Asian Orogenic Belt (CAOB). The position of Eastern part of MML is widely discussed at recent time, since, this is an important for reconstruction of geodynamic evolution of this region. Some researchers suggest that ophiolite from the Erdene Uul and Maykhan Tsakhir Uul mountain ranges are Eastern part of an ophiolitic nappe system thrust northwards over the Dzabkhan-Baydrag continent, namely the Khantaishir and the Dariv ophiolites [Štípská et al., 2010; Buriánek et al., 2017]. Others have a different view, they suggest that investigated ophiolites refers to Gobi-Altai ophiolite system (523±5 – 518±6 Ma), which likely formed in front of the Gobi Altai microcontinent by initiation of a new southdipping subduction zone following arc–microcontinent collision in Northwest Mongolia [Jian et al., 2014]. However, ophiolites of this critical region of Mongolian the CAOB have not been investigated in detail
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