Estimation of hysteresis loss in Sm₁Ba₂Cu₃O_7−δ coated conductor via scanning Hall probe measurements with simultaneously applied field and current

Yoo, Jaeun,Lee, SangMoo,Jung, YeHyun,Kwak, Kisung,Rhee, Joonkyu,Youm, Dojun,Kim, Hosup,Ha, Hongsoo,Oh, SangSoo,Oh, Sangjun IOP Publishing Ltd 2009 Superconductor science & technology Vol.22 No.4

<P>The hysteresis loss in a Sm<SUB>1</SUB>Ba<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>7−δ</SUB> coated conductor was estimated from magnetic field profiles measured by the scanning Hall probe method. Current, <I>I</I><SUB>a</SUB>, and magnetic field, <I>B</I><SUB>a</SUB>, were applied simultaneously; <I>B</I><SUB>a</SUB> was applied in the normal direction with respect to the tape surface. <I>B</I><SUB>a</SUB> and <I>I</I><SUB>a</SUB> were varied from <I>B</I><SUB>peak</SUB> to −<I>B</I><SUB>peak</SUB> and from <I>I</I><SUB>peak</SUB> to −<I>I</I><SUB>peak</SUB>, respectively, with the ratio α = <I>I</I><SUB>a</SUB>/<I>B</I><SUB>a</SUB> fixed during the variation. Three values of α were taken for the three load lines. The values of <I>B</I><SUB>peak</SUB>/<I>I</I><SUB>peak</SUB> were varied from 0 mT/0 A to 10.7 mT/116 A, 99.1 mT/50 A, and 298.2 mT/46.1 A, respectively, for the three load lines. From the measured values of magnetic field profiles, the current profiles were calculated by the iterative inversion method. From the current profiles, the flux density profiles and the hysteresis loss, <I>Q</I>, were then calculated for various values of <I>I</I><SUB>peak</SUB>(= α<I>B</I><SUB>peak</SUB>) in each load line. The results were compared with theoretical calculations based on Brandt’s model. When <I>B</I><SUB>peak</SUB> was about 300 mT, the estimated values of <I>Q</I> were several times smaller than the theoretical values of <I>Q</I> with the self-field <I>I</I><SUB>c0</SUB>. The low value of <I>Q</I> in this case is due to the field dependent <I>I</I><SUB>c</SUB> and the saturation effect of the current profiles, which results in significant reduction of the induced magnetic moment, <I>M</I>. </P>

Study of resonance formation in the mass region 1400−1500MeV through the reaction <i>γγ</i>&to;K⁰_SK^±π^∓

IOP Publishing Ltd 2007 Journal of high energy physics Vol.2007 No.3

The K<SUP>0</SUP><SUB>S</SUB>K<SUP>±</SUP>π<SUP>∓</SUP> final state in two-photon collisions is studied with the L3 detector at LEP at e<SUP>+</SUP>e<SUP>−</SUP> centre-of-mass energies from 183 to 209 GeV with an integrated luminosity of 664.6 pb<SUP>−1</SUP>. The <I>η</I>(1475) and f<SUB>1</SUB>(1420) mesons are observed and their contribution is separated by measuring the formation rates as a function of the photon virtuality<I>Q</I><SUP>2</SUP>. The <I>η</I>(1475) is found to be dominant for <I>Q</I><SUP>2</SUP> ≤ 0.01GeV<SUP>2</SUP> and its two-photon width is measured to be 0.23±0.05 (stat.) ±0.05 (sys.) keV. At higher <I>Q</I><SUP>2</SUP>,the f<SUB>1</SUB>(1420) is formed and decays to K<SUP>*</SUP>(892)K. The <I>γγ</I> coupling and form factor parameters of this state are measured to beΓ<SUB><I>γγ</I></SUB> = 3.2±0.6 (stat.) ±0.7 (sys.) keV andΛ<SUB>1</SUB> = 926±72 (stat.) ±32 (sys.) MeV, respectively.

&calM;-theory on pp-waves with a holomorphic superpotential and its membrane and matrix descriptions

Kim, Jongwook,Kim, Nakwoo,Park, Jeong-Hyuck,Plefka, Jan IOP Publishing Ltd 2008 Journal of high energy physics Vol.2008 No.8

We study a new class of inhomogeneous pp-wave solutions with 8 unbroken supersymmetries in <I>D</I> = 11 supergravity. The 9 dimensional transverse space is Euclidean and split into 3 and 6 dimensional subspaces. The solutions have non-constant gauge flux, which are described in terms of an arbitrary holomorphic function of the complexified 6 dimensional space. The supermembrane and matrix theory descriptions are also provided and we identify the relevant supersymmetry transformation rules. The action also arises through a dimensional reduction of &calN; = 1, <I>D</I> = 4 supersymmetric Yang-Mills theory coupled to 3 gauge adjoint and chiral multiplets, whose interactions are determined by the holomorphic function of the supergravity solution now constituting the superpotential.

AdS₃ solutions of IIB supergravity from D3-branes

IOP Publishing Ltd 2006 Journal of high energy physics Vol.2006 No.1

We consider pure D3-brane configurations of IIB string theory which lead to supersymmetric solutions containing an AdS<SUB>3</SUB> factor. They can provide new examples of AdS<SUB>3</SUB>/CFT<SUB>2</SUB> duality pairs on D3-branes whose worldvolume is partially compactified. When the internal 7 dimensional space is non-compact, they can be identified as supersymmetric fluctuations of higher dimensional AdS solutions and are in general dual to 1/8-BPS operators thereof. We find that supersymmetry requires the 7 dimensional space take the form of a warped <I>U</I>(1) fibration over a 6 dimensional Kahler manifold.

Vector susceptibility and QCD phase transition in AdS/QCD models

Jo, KwangHyun,Kim, Youngman,Lee, Hyun Kyu,Sin, Sang-Jin IOP Publishing Ltd 2008 Journal of high energy physics Vol.2008 No.11

We calculate the vector isospin susceptibility in AdS/QCD models to study QCD phase transition. In the hard wall model, we show explicitly that the infalling boundary condition at the horizon can be treated as a Dirichlet boundary with a fine-tuned boundary value in the zero frequency and momentum limit. With the infalling boundary condition, we uniquely determine the overall normalization of the vector isospin susceptibility in the hard wall model. In the framework of the soft wall model, we obtain the vector isospin susceptibilitywith and without Hawking-Page transition and compare our results with lattice QCD. We briefly discuss the chiral symmetry restoration in the AdS/QCD models.

Spiky strings on AdS₄ × <b>CP</b>³

Lee, Bum-Hoon,Panigrahi, Kamal L.,Park, Chanyong IOP Publishing Ltd 2008 Journal of high energy physics Vol.2008 No.11

We study a giant magnon and a spike solution for the string rotating on <I>AdS</I><SUB>4</SUB> × <B>CP</B><SUP>3</SUP> geometry. We consider rigid rotating fundamental string in the SU(2) × SU(2) sector inside the <B>CP</B><SUP>3</SUP> and find out the general form of all the conserved charges. We find out the dispersion relation corresponding to both the known giant magnon and the new spike solutions. We further study the finite size correction in both cases.

Neutrino masses from cosmological probes in interacting neutrino dark-energy models

Ichiki, Kiyotomo,Keum, Yong-Yeon IOP Publishing Ltd 2008 Journal of high energy physics Vol.2008 No.6

We investigate whether interaction between massive neutrinos and quintessence scalar field is the origin of the late time accelerated expansion of the universe. We present explicit formulas of the cosmological linear perturbation theory in the neutrinos probes of dark-energy model, and calculate cosmic microwave background anisotropies and matter power spectra. In these models, the evolution of the mass of neutrinos is determined by the quintessence scalar field, which is responsible for a varying effective equation of states; ω<SUB>eff</SUB>(<I>z</I>) goes down lesser than -1. We consider several types of scalar field potential and put constraints on the coupling parameter between neutrinos and dark energy. By combining data from cosmic microwave background (CMB) experiments including the WMAP 3-year results, large scale structure with 2dFGRS data sets, we constrain the hypothesis of massive neutrinos in the mass-varying neutrino scenario. Assuming the flatness of the universe, the constraint we can derive from the current observation is ∑<I>m</I><SUB>ν</SUB> < 0.45 eV at 1σ (0.87 eV at 2σ) confidence level for the sum over three species of neutrinos. The dynamics of scalar field and the impact of scalar field perturbations on cosmic microwave background anisotropies are discussed. We also discuss on the instability issue and confirm that neutrinos are stable against the density fluctuation in our model.

Superconformal defects in the tricritical Ising model

Gang, Dongmin,Yamaguchi, Satoshi IOP Publishing Ltd 2008 Journal of high energy physics Vol.2008 No.12

We study superconformal defect lines in the tricritical Ising model in 2 dimensions. By the folding trick, a superconformal defect is mapped to a superconformal boundary of the &calN; = 1 superconformal unitary minimal model of <I>c</I> = 7/5 with <I>D</I><SUB>6</SUB>−<I>E</I><SUB>6</SUB> modular invariant. It turns out that the complete set of the boundary states of <I>c</I> = 7/5 <I>D</I><SUB>6</SUB>−<I>E</I><SUB>6</SUB> model cannot be interpreted as the consistent set of superconformal defects in the tricritical Ising model since it does not contain the ``no defect'' boundary state. Instead, we find a set of 18 consistent superconformal defects including ``no defect'' and satisfying the Cardy condition. This set also includes some defects which are not purely transmissive or purely reflective.

Minimal dark matter in type III seesaw

IOP Publishing Ltd 2009 Journal of high energy physics Vol.2009 No.12

We explore the possibility of a new dark matter candidate in the supersymmetric type III seesaw mechanism where a neutral scalar component of the <I>Y</I> = 0 triplet can be the lightest supersymmetric particle. Its thermal abundance can be in the right range if non-standard cosmology such as kination domination is assumed. The enhanced cross-section of the dark matter annihilation to <I>W</I><SUP>+</SUP><I>W</I><SUP>−</SUP> can leave detectable astrophysical and cosmological signals whose current observational data puts a lower bound on the dark matter mass.The model predicts the existence of a charged scalar almost degenerate with the dark matter scalar and its lifetime lies between 5.5 cm and 6.3 m. It provides a novel opportunity of the dark mater mass measurement by identifying slowly-moving and highly-ionizing tracks in the LHC experiments. If the ordinary lightest supersymmetric particle is the usual Bino, its decay leads to clean signatures of same-sign dilepton and di-charged-scalar associated with observable displaced vertices which are essentially background-free and can be fully reconstructed.

Two-loop test of the &calN; = 6 Chern-Simons theory <i>S</i>-matrix

Ahn, Changrim,Nepomechie, Rafael I. IOP Publishing Ltd 2009 Journal of high energy physics Vol.2009 No.3

Starting from the integrable two-loop spin-chain Hamiltonian describing the anomalous dimensions of scalar operators in the planar &calN; = 6 superconformal Chern-Simons theory of ABJM, we perform a direct coordinate Bethe ansatz computation of the corresponding two-loop <I>S</I>-matrix. The result matches with the weak-coupling limit of the scalar sector of the all-loop <I>S</I>-matrix which we have recently proposed. In particular, we confirm that the scattering of &calA; and &calB; particles is reflectionless. As a warm up, we first review the analogous computation of the one-loop <I>S</I>-matrix from the one-loop dilatation operator for the scalar sector of planar &calN; = 4 superconformal Yang-Mills theory, and compare the result with the all-loop SU(2|2)<SUP>2</SUP> <I>S</I>-matrix.