120358883
Spin coupling resonance and suppression in the AGS
117036088
Comparison of multipole expansion and exact form of the eddy current field of the AGS Booster
Studies are made on magnetic field representation using a multipole expansion as well as the exact form to calculate the magnetic field produced by eddy currents in the vacuum chamber of the AGS Booster as well as the field produced by three turn correction coils attached to the top and bottom of the vacuum chamber. The multiple representation of the chamber field does not converge to the next field when X > 30mm and limits the particle motion. When the exact form of the chamber field is used, initial amplitudes in the horizontal plane (measured at QF) can be nearly as large as the chamber half aperture. Use of three turn correction coils to compensate the eddy current fields seems to reduce rather than increase the acceptance. 6 figs., 3 tabs.
124338422
FIRST OBSERVATION OF A SNAKE DEPOLARIZING RESONANCE
Using a 104MeV stored polarized proton beam and a full Siberian snake, we recently found evidence for a so-called {open_quotes}snake{close_quotes} depolarizing resonance. A full Siberian snake forces the spin tune {nu}{sub s} to be a half integer. Thus, if the vertical betatron tune {nu}{sub y} is set near a quarter integer, then the {nu}{sub s}=n{plus_minus}2{nu}{sub y} second-order snake resonance can depolarize the beam. Indeed, with a full Siberian snake, we found a deep depolarization dip when {nu}{sub y} was equal to 4.756; moreover, when {nu}{sub y} was changed to 4.781, the deep dip disappeared and the polarization was preserved. {copyright} {ital 1997} {ital The American Physical Society}
120417645
Snakes and spin rotators for high energy accelerators
Abstract A modification to the continuous family of snake and spin rotators, discovered by Steffen, is discussed. A compact snake configuration is found to have the advantages of requiring a smaller total integrated dipole magnet strength and a smaller transverse displacement for circulating particles. A split snake configuration has the advantage of allowing an entire experimental insertion region to be located between the two halves of the snake. Such configurations could serve as both a snake and a 90° spin rotator for experiments requiring different helicity states. General properties of these snake configurations are discussed.
96454816
Design and fabrication of a multi-purpose Panofsky magnet
A fast, flexible magnet system, consisting of a Panofsky style ferrite picture-frame magnet and pulsed power supply, has been developed. Magnet specifications are: 8 cm /spl times/8 cm aperture, 23 cm length, 500 A pulsed/l60 A DC, and 1 /spl mu/s risetime. Designed for general accelerator physics studies, the magnet may be quickly converted from dipole to quadrupole or sextupole and higher multipole configurations by easily changing winding end terminations. In the quadrupole configuration a field gradient of 0.5 T/m is achieved at 500 A. This magnet has become an important tool for nonlinear beam dynamics experiments at the IUCF Cooler Ring.<<ETX>>
120908048
Comment on “Quasiperiodic spin-orbit motion and spin tunes in storage rings”
53130301
Exact third-order density perturbation and one-loop power spectrum in general dark energy models
Abstract Under the standard perturbation theory (SPT), we obtain the fully consistent third-order density fluctuation and kernels for the general dark energy models without using the Einstein–de Sitter (EdS) universe assumption for the first time. We also show that even though the temporal and spatial components of the SPT solutions cannot be separable, one can find the exact solutions to any order in general dark energy models. With these exact solutions, we obtain the less than % error correction of one-loop matter power spectrum compared to that obtained from the EdS assumption for k = 0.1 h Mpc − 1 mode at z = 0 ( 1 , 1.5 ) . Thus, the EdS assumption works very well at this scale. However, if one considers the correction for P 13 , the error is about 6 (9, 11)% for the same mode at z = 0 ( 1 , 1.5 ) . One absorbs P 13 into the linear power spectrum in the renormalized perturbation theory (RPT) and thus one should use the exact solution instead of the approximation one. The error on the resummed propagator N of RPT is about 14 (8, 6)% at z = 0 ( 1 , 1.5 ) for k = 0.4 h Mpc − 1 . For k = 1 h Mpc − 1 , the error correction of the total matter power spectrum is about 3.6 (4.6, 4.5)% at z = 0 ( 1 , 1.5 ) . Upcoming observation is required to archive the sub-percent accuracy to provide the strong constraint on the dark energy and this consistent solution is prerequisite for the model comparison.
119474240
Model-independent properties of the B-meson distribution amplitude
The operator product expansion is used to obtain model-independent predictions for the first two moments of the renormalized $B$-meson light-cone distribution amplitude ${\ensuremath{\phi}}_{+}^{B}(\ensuremath{\omega},\ensuremath{\mu})$, defined with a cutoff $\ensuremath{\omega}\ensuremath{\le}{\ensuremath{\Lambda}}_{\mathrm{UV}}$. The leading hadronic power corrections are given in terms of the parameter $\overline{\ensuremath{\Lambda}}={m}_{B}\ensuremath{-}{m}_{b}$. From the cutoff dependence of the zeroth moment an analytical expression for the asymptotic behavior of the distribution amplitude is derived, which exhibits a negative radiation tail for $\ensuremath{\omega}\ensuremath{\gg}\ensuremath{\mu}$. By solving the evolution equation for the distribution amplitude, an integral representation for ${\ensuremath{\phi}}_{+}^{B}(\ensuremath{\omega},\ensuremath{\mu})$ is obtained in terms an initial function ${\ensuremath{\phi}}_{+}^{B}(\ensuremath{\omega},{\ensuremath{\mu}}_{0})$ defined at a lower renormalization scale. A realistic model of the $B$-meson light-cone distribution amplitude is proposed, which satisfies the moment relations and has the correct asymptotic behavior. This model provides an estimate for the first inverse moment and the associated parameter ${\ensuremath{\lambda}}_{B}$.
7063414
Mass-Deformed Bagger-Lambert Theory and its BPS Objects
We find a 16-supersymmetric mass-deformed Bagger-Lambert theory with SO(4)xSO(4) global R symmetry. The R charge plays the role of the noncentral term in the superalgebra. This theory has one symmetric vacuum and two inequivalent broken sectors of vacua. Each sector of the broken symmetry has SO(4) geometry. We find the 1/2 BPS domain walls connecting the symmetric phase and any broken phase, and 1/4 BPS supertubelike objects, which may appear as anyonic q-balls in the symmetric phase or vortices in the broken phase. We also discuss mass deformations, which reduce the number of supersymmetries.
119218989
Holographic description of quantum field theory
Abstract We propose that general D-dimensional quantum field theories are dual to ( D + 1 ) -dimensional local quantum theories which in general include objects with spin two or higher. Using a general prescription, we construct a ( D + 1 ) -dimensional theory which is holographically dual to the D-dimensional O ( N ) vector model. From the holographic theory, the phase transition and critical properties of the model in dimensions D > 2 are described.
119173091
Order in a Spatially Anisotropic Triangular Antiferromagnet
The phase diagram of the spin-1/2 Heisenberg antiferromagnet on an anisotropic triangular lattice of weakly coupled chains is investigated using a renormalization group analysis which includes marginal couplings important for connecting to numerical studies of this model. In particular, the relative stability of incommensurate spiral spin density order and collinear antiferromagnetic order is studied. While incommensurate spiral order is found to exist over most of the phase diagram in the presence of a Dzyaloshinskii-Moriya (DM) interaction, at small interchain coupling and extremely weak DM coupling, collinear antiferromagnetic order can survive. The implications of the renormalization group analysis for numerical studies, many of which have found spin liquid-like behaviour, are discussed.