928 research outputs found
Angular dependent planar metamagnetism in the hexagonal compounds TbPtIn and TmAgGe
Detailed magnetization measurements, M(T,H,theta), were performed on single
crystals of TbPtIn and TmAgGe (both members of the hexagonal Fe_2P/ZrNiAl
structure type), for the magnetic field H applied perpendicular to the
crystallographic c axis. These data allowed us to identify, for each compound,
the easy-axes for the magnetization, which coincided with high symmetry
directions ([120] for TbPtIn and [110] for TmAgGe). For fixed orientations of
the field along each of the two six-fold symmetry axes, a number of
magnetically ordered phases is being revealed by M(H,T) measurements below T_N.
Moreover, T ~ 2 K, M(H)|_theta measurements for both compounds (with H applied
parallel to the basal plane), as well as T = 20 K data for TbPtIn, reveal five
metamagnetic transitions with simple angular dependencies: H_{ci,j} ~
1/cos(theta +/- phi), where phi = 0^0 or 60^0. The high field magnetization
state varies with theta like 2/3*mu_{sat}(R^{3+})*cos(theta), and corresponds
to a crystal field limited saturated paramagnetic, CL-SPM, state. Analysis of
these data allowed us to model the angular dependence of the locally saturated
magnetizations M_{sat} and critical fields H_c with a three coplanar Ising-like
model, in which the magnetic moments are assumed to be parallel to three
adjacent easy axes. Furthermore, net distributions of moments were inferred
based on the measured data and the proposed model
Nonperturbative QCD Phenomenology and Light Quark Physics
Recent progress in modeling QCD for hadron physics through truncated
Dyson-Schwinger equations is reviewed. Special emphasis is put upon comparison
of dressed quark propagators and the dressed quark-gluon vertex with
lattice-QCD results.Comment: 6 pages, 7 figures. Invited talk at the QCD Down Under workshop at
the CSSM/University of Adelaide, March 200
High-Spin "Stretched" States Excited in (p,n) Reactions
This work was supported by the National Science Foundation Grant NSF PHY 78-22774 A02 & A03 and by Indiana Universit
High-Spin States in Nuclei Excited Via the (p,n) Reactions
Supported by the National Science Foundation and Indiana Universit
Neutron Knockout Reactions
This work was supported by the National Science Foundation Grant NSF PHY 78-22774 A02 & A03 and by Indiana Universit
Spectroscopy with the (d,n) Reaction at 80 MeV
This work was supported by the National Science Foundation Grant NSF PHY 81-14339 and by Indiana Universit
Prominent bulk pinning effect in the MgB_2 superconductor
We report the magnetic-field dependence of the irreversible magnetization of
the recently discovered binary superconductor MgB. For the temperature
region of , the contribution of the bulk pinning to the
magnetization overwhelms that of the surface pinning. This was evident from the
fact that the magnetization curves, , were well described by the
critical-state model without considering the surface pinning effect. It was
also found that the curves at various temperatures scaled when the field
and the magnetization were normalized by the characteristic scaling factors
and , respectively. This feature suggests that the
pinning mechanism determining the hysteresis in is unique below .Comment: 4pages and 4 figures. Phys. Rev. B (accepted
Relativistic D-brane Scattering is Extremely Inelastic
We study the effects of quantum production of open strings on the
relativistic scattering of D-branes. We find strong corrections to the brane
trajectory from copious production of highly-excited open strings, whose
typical oscillator level is proportional to the square of the rapidity. In the
corrected trajectory, the branes rapidly coincide and remain trapped in a
configuration with enhanced symmetry. This is a purely stringy effect which
makes relativistic brane collisions exceptionally inelastic. We trace this
effect to velocity-dependent corrections to the open-string mass, which render
open strings between relativistic D-branes surprisingly light. We observe that
pair-creation of open strings could play an important role in cosmological
scenarios in which branes approach each other at very high speeds.Comment: 30 pages; added references and a comment about velocity-dependent
masse
QCD modeling of hadron physics
We review recent developments in the understanding of meson properties as
solutions of the Bethe-Salpeter equation in rainbow-ladder truncation. Included
are recent results for the pseudoscalar and vector meson masses and leptonic
decay constants, ranging from pions up to c\bar{c} bound states; extrapolation
to b\bar{b} states is explored. We also present a new and improved calculation
of F_\pi(Q^2) and an analysis of the \pi\gamma\gamma transition form factor for
both \pi(140) and \pi(1330). Lattice-QCD results for propagators and the
quark-gluon vertex are analyzed, and the effects of quark-gluon vertex dressing
and the three-gluon coupling upon meson masses are considered.Comment: 17 pages, 19 postscript figures, contribution to the proceedings of
LC05, Cairns, Australia, July 200
Analyzing Power Measurements for (p,n) Reactions
This work was supported by the National Science Foundation Grant NSF PHY 78-22774 A02 & A03 and by Indiana Universit
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