35465935
Acceleration of polarized proton in high energy accelerators
The understanding of polarized proton acceleration in the high energy accelerator is reviewed. In high energy accelerators, snakes are needed to preserve polarization. The author analyzes the effects of snake resonances, snake imperfections, and overlapping resonances on spin depolarization. He discusses results of snake experiments at the IUCF (Indiana University Cyclotron Facility) cooler ring. The snake can be overcome by various kinds of spin depolarization resonances. These experiments pointed out that a partial snake can be used to cure the imperfection resonances in low to medium energy accelerators.<<ETX>>
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}
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.
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”
117701762
Origin of Cosmic Acceleration with Large Scale Structure
The current accelerating universe can be explained by adding an exotic energy density with a negative pressure or modifying the gravity. Both the physical energy component and the modification of gravity can give rise to an effective dark energy equation of state which can characterize the expansion history of the universe. To distinguish the true origin of the cosmic acceleration, we need to know experiments giving both the expansion history of the universe and the growth rate of matter density fluctuations. Large scale structure surveys can satisfy this requirement. We investigate the Integrated Sachs Wolfe effect as one of possible methods to constrain the effective dark energy equation of state.
118495217
Evidence for departure from \Lambda CDM with LSS
We investigate the growth index parameter \gamma and the time variation of the gravitational constant G_{eff} by using the currently available growth function f(z) data at different redshifts, with and without scaling to the fiducial \Lambda CDM model. We inquire the four different models of \gamma including a constant \gamma. From a \chi^2 minimization, we constrain the parameter spaces of models and show that \Lambda CDM model is excluded by 1-\sigma level from current f(z) data. G_{eff} is different from the Newton's gravitational constant G_{N} in modified gravity theories and interestingly, the current data shows that G_{eff} \neq G_{N} at z \gtrsim 0.2 \sim 0.3 at 3-\sigma level. From these, we conclude that Einstein's General Relativity with \Lambda CDM is ruled out by 99% confidence level from large scale structure observations.
118495503
Factorization at subleading power and irreducible uncertainties in $ \bar{B} \to {X_s}\gamma $ decay
Using methods from soft-collinear and heavy-quark effective theory, a systematic factorization analysis is performed for the $ \bar{B} \to {X_s}\gamma $ photon spectrum in the endpoint region $ {m_b} - 2{E_\gamma } = \mathcal{O}\left( {{\Lambda_{\text{QCD}}}} \right) $. It is proposed that, to all orders in 1/mb, the spectrum obeys a novel factorization formula, which besides terms with the structure H J ⊗ S familiar from inclusive $ \bar{B} \to {X_u}l\bar{\nu } $ decay distributions contains “resolved photon” contributions of the form $ H\;J \otimes S \otimes \bar{J} $ and $ H\;J \otimes S \otimes \bar{J} \otimes \bar{J} $. Here S and $ \bar{J} $ are new soft and jet functions, whose form is derived. These contributions arise whenever the photon couples to light partons instead of coupling directly to the effective weak interaction. The new contributions appear first at order 1/mb and are related to operators other than Q7γ in the effective weak Hamiltonian. They give rise to non-vanishing 1/mb corrections to the total decay rate, which cannot be described using a local operator product expansion. A systematic analysis of these effects is performed at tree level in hard and hard-collinear interactions. The resulting uncertainty on the decay rate defined with a cut Eγ > 1.6 GeV is estimated to be approximately ±5%. It could be reduced by an improved measurement of the isospin asymmetry Δ0− to the level of ±4%. We see no possibility to reduce this uncertainty further using reliable theoretical methods.
118665630
Neutron Skin size dependence of the nuclear binding energy
The nuclear binding energy is studied using a finite temperature density functional theory. A Skyrme interaction is used in this work. Volume, surface, and symmetry energy contributions to the binding energy are investigated. The case of neutron skin is considered in detail. The neutron skin modifies the mass $A$ dependence of various terms and $I$ dependence of the skin thickness is proportional to $I$ for the case of same central density.
54853460
Study of the standard model Higgs boson partial widths and branching fractions
The discovery of the Higgs boson, with a mass known to be better than the percent level, enables precision Higgs boson analyses for the first time. Toward this goal, we define an expansion formalism of the Higgs boson partial widths and branching fractions that facilitates such studies. This expansion yields the observables as a perturbative expansion around reference values of Standard Model input observables (quark masses, QCD coupling constant, etc.). We compute the coefficients of the expansion using state-of- the-art results. We also study the various sources of uncertainties in computing the partial widths and branching fractions more precisely. We discuss the impact of these results with efforts to discern new physics through precision Higgs boson studies. With the discovery of the Higgs boson (1), particle physics is entering a new era of precision studies of the Higgs sector. The observables are many and include the Higgs boson mass, its total decay width, its spin, its decay branching fractions to Standard Model (SM) particles, its possible decay branching fractions to other exotic final states, and its various production rates at colliders. All of these observables will be studied carefully in time. The theory under primary consideration in this article is the Standard Model. The subpercent-level determination of the Higgs boson mass now enables a complete set of input observables whereby any perturbative high-energy observ- able involving the Higgs boson can be predicted. In this article, our focus is on the careful exposition of the decay partial widths and branching fractions of a SM Higgs boson with mass near 126 GeV. Our goal is to provide state-of-the-art formulas that can be used in any precision electroweak analysis to investigate compatibility of the data with the SM predictions in these most fundamental and sensitive observables. Other calculations exist in the literature, 1 most notably from the computer program HDECAY (2); however, we wish to provide an independent calculation that includes the latest advances and allows us to vary the renormalization scale in all parts of the computations. This flexibility will be useful in later discussions regarding uncertainties. We also aim to detail the errors that each input into the computation propagates to the final answer for each observable (3). In some cases, these uncertainties are large, and constitute a limitation to how sensitive experimental measurements can be in determining the underlying theory parameters. Finally, we discuss some implications for physics beyond the SM sensitivities in precision Higgs studies.