122238217
A relation between the charge radii of π+,K+,K0 derived by the general QCD parametrization
We derive, using the general QCD parametrization, the approximate relation r2(π+) − r2(K+) − r2(K0) where the r's are the charge radii. The relation is satisfied but the experimental errors are still sizeable. The derivation is similar to (but even simpler than) that for r2(p) − r2(n) r2(Δ+) (Phys. Lett. B, 448 (1999) 107).
35083522
Field theory and the nonrelativistic quark model: A parametrization of the meson masses.
We apply the method developed in previous papers (Phys. Rev. D 40, 2997 (1989); 40, 3111 (1989)) to write a general parametrization of the masses of the lowest meson nonets. We compare the mass formulas obtained in this way with those used currently in a nonrelativistic quark model (NRQM). As in the previous work, the aim is to separate the features specific to the NRQM from those that follow from a relativistic field theory satisfying a few rather general conditions (satisfied by QCD). For the meson masses it turns out that the formulas obtained from field theory have essentially the same structure and number of parameters as those in the NRQM. This explains the good fit that the NRQM provides in this case; the internal {ital v}/{ital c} of the {ital q{bar q}} pair is irrelevant. As a by- product, the mixing angle for the {ital I}=0 mesons (e.g., {eta} and {eta}{prime}) predicted from the masses turns out to be model independent to first order in flavor breaking. We discuss the question of the linear versus quadratic or, say, square-root mixing angles.
119236559
Some remarks on a paper by G.-S. Yang and H.-C.Kim: Mass splitting of SU(3) baryons within a chiral soliton model
In a recent paper Yang and Kim discuss the lowest baryon mass formulas using a chiral soliton model. However, contrary to their assertion, their result is not equivalent to a generalized Gell Mann-Okubo mass formula derived (G.Morpurgo,1992) using only general properties of QCD (The General Parameterization method). The reason for the non equivalence is that the generalized mass formula includes all the main terms that break flavor at second order, whereas the Authors above do not go beyond first order flavor breaking (and should therefore find the usual Gell Mann Okubo formula). This is not so, due to some inconsistencies. Below we confine to the part of the Yang-Kim paper dealing with the mass formula. We will not consider the other items of their paper. 1.Second order versus first order in flavor breaking. As stated in the Abstract, I will consider only the part of the paper of Yang and Kim [1] dealing with the Gell Mann-Okubo mass formula (see the generalized Gell Mann-Okubo mass formula Eqs.(1) below) derived [2] many years ago. In the Eqs.(1,2) below the particle symbols stay for the particle masses. 1 2 (p+ Ξ) + T = 1 4 (3Λ + 2Σ − Σ) (1) where T stays for T ≡ Ξ∗− − 1 2 (Ω + Σ∗−) (2) The fit to the data depends on whether we use the conventional or the pole values for the masses of the resonances appearing in T : l.h.s. = 1132.36± 0.7MeV, r.h.s. = 1133.93± 0.04MeV (conventional) l.h.s. = 1133.86± 1.25MeV, r.h.s. = 1133.93± 0.04MeV (pole) (3) In Eq.(1) the value of T is 5.7±0.7MeV . The Eq.(1), written with the signs of the charges indicated in it, includes correctly the effects of the e.m. contributions to the masses. (See in Ref.[2], the text and the footnote 9). Note from Eq.(3) e-mail morpurgo@ge.infn.it
14665617
Comment on "Chiral symmetry and the intrinsic structure of the nucleon"- by D.B.Leinweber,A.W.Thomas and R.D.Young
Some remarks are presented on a recent paper (Leinweber,Thomas and Young, Phys.Rev.Lett. 86, 5011, 2001). In particular a statement of the above paper on the fact that the ratio between the magnetic moments of proton and neutron should remain constant at -3/2, independent of the change of the quark mass is discussed on the basis of the general parameterization.
123073842
QCD with pion exchange, double counting and the baryon magnetic moments
124837005
SEARCH FOR QUARKS WITH THE FERROMAGNETIC LEVITATION ELECTROMETER
85527168
A METHOD TO MEASURE THE BETA-BEATING IN A 90 DEGREES PHASE ADVANCE LATTICE
A method to compute the beta-beating in an accelerator, using as input the measurement of the phase advance of a betatron oscillation between three BPMs (beam position monitors), had been developed in the past[1]. The beauty of this method is that the result does not depend on the the BPM relative errors on the measurement of the oscillation amplitude. Unfortunately this method is not applicable when the phase advance between two of the three BPMs is (close to) 180 degrees. In this latter case the measurement of the amplitude of the beam oscillation should be combined with the phase advance measurement to get a complete picture of the beta-beating. Detecting and filtering BPMs with large gain errors requires some care. A method dealing with these aspects has been developed. Examples obtained by applying the method to real data from LEP and SPS are shown.
55438680
THE ELECTRICAL CIRCUIT DESCRIPTION FOR THE LHC
The LHC is a very complex machine, made of about 8000 superconducting magnets along a circumference of 26.7 km. The magnets are powered in about 1700 different electrical circuits with currents ranging from 60 A (for small corrector magnets) up to 13 kA for the main dipoles and quadrupoles. The layout of the powering system reflects the complexity of the accelerator. About 80000 high current connections will have to be made. A minor fault in a circuit or one of the superconducting connections would have severe consequences for accelerator operation. For the integration of the electrical equipment, for supporting the assembly and verifying the correctness of the electrical circuits, all relevant information should be included in one coherent database. A simple method for the description of the electrical circuits is proposed, while an associated tool is translating this input into database information and back, checking the circuit description at the same time for inconsistencies. Out of the database information, electrical drawings and detailed views of the electrical connections at every LHC interconnection point can be recreated. This paper describes the approach and outlines several possible applications.
117272397
Non-linear Resonances with Stong Radiation Damping in LEP
107525573
The Q-Loop : a Function Driven Feedback System for the Betatron Tunes During the LEP Energy Ramp
In normal operation LEP is ramped from injection energy, typically 22 GeV, to energies of over 90 GeV where physics taking takes place. Effective control of the betatron during the ramp is essential to ensure good transmission of stored current. The LEP Q-loop is a feedback system used to control the tunes during the energy ramp. By following a pre-programmed tune function it provides a means of avoiding dangerous resonances and thus beam loss. The basic components the Q-loop will be described, and operational results presented. Emphasis will be given to the problems encountered and the solutions found.
119009661
Determination of coupled-lattice properties using turn-by-turn data
A formalism for extracting coupled betatron parameters from multiturn, shock excited, beam position monitor data is described. The most important results are nonperturbative in that they do not rely on the underlying ideal lattice model. Except for damping, which is assumed to be exponential and small enough to be removed empirically, the description is symplectic. As well as simplifying the description, this leads to self-consistency checks that are applied to the data. The most important of these is a {open_quotes}magic ratio{close_quotes} of Fourier coefficients that is required to be a lattice invariant, the same at every beam position monitor. All formulas are applied to both real and simulated data. The real data was acquired June, 1992 at LEP as part of decoupling studies, using the LEP beam orbit measurement system. Simulated data, obtained by numerical tracking (TEAPOT) in the same (except for unknown errors) lattice, agrees well with real data when subjected to identical analysis. For both datasets, deviations between extracted and design parameters and deviations from self-consistency can be accounted for by noise and signal processing limitations. This investigation demonstrates that the LEP beam position system yields reliable local coupling measurements. It can be conservatively assumed that systems of similar design at the SSC and LHC will provide the measurements needed for local decoupling.