27222284
Relation of constituent quark models to QCD: Why several simple models work "so well"
We discuss the relationship between exact QCD and constituent quark models (nonrelativistic, bag, or others) to clarify why different models work reasonably in many cases. For this we use the general parametrization method [G. Morpurgo, Phys. Rev. D {bold 40}, 2997 (1989)] now expressed in terms of the standard current quark fields ({ital m}{sub {ital u}} and {ital m}{sub {ital d}} a few MeV; {ital m}{sub {ital s}}{approx_equal}150 MeV, at the usual mass renormalization point {ital q}=1 GeV). The method provides for several quantities the most general exact form of the spin-flavor structure derivable from the QCD Lagrangian. We can thus determine for many important quantities (masses of lowest baryons and mesons, baryon magnetic moments, semileptonic decays, etc.), from a fit to the data, the coefficients of the parametrization, the same ones that a direct QCD calculation, if feasible, would give. It turns out that only a few coefficients are relatively important. Because different models, each with its few free parameters, can produce these terms by some choice of parameters, one can see why models so different as the nonrelativistic or quasichiral models work {open_quote}{open_quote}well.{close_quote}{close_quote} Finally, expressing the coefficients in the general parametrization dimensionally in terms of current quark massesmore » and {Lambda}, we find that the {ital m}{sub {ital s}} expansion of broken SU(3){times}SU(3) is just an expansion in {Delta}{ital m}/({xi}{Lambda}){approx_equal}{ital m}{sub {ital s}}/({xi}{Lambda}){approx_equal}0.3. The {xi}{close_quote}s determined from different data are rather close (from 2.3 to 3.7). The resulting effective light quark masses in constituent models are of order ({xi}{Lambda}). None of the above conclusions depend on whether or not the chiral limit {ital m}{sub {ital u}},{ital m}{sub {ital d}},{ital m}{sub {ital s}}{r_arrow}0 is mathematically sound. {copyright} {ital 1996 The American Physical Society.}« less
120776511
The non-relativistic quark model
The classification scheme and decay properties of hadron states are investigated in the framework of the non relativistic quark model. The main successes and the unsolved difficulties of the model are presented indicating the future work which could be done to understand and exploit the non-relativistic quark ideas.РезюмеИсследованы схема классификации и распадные свойства адронов в рамках статической модели кварков. Изложены главные успехи и нерешенные проблемы модели, указывая задачи, которые должны быть решены для лучшего понимания и использования нерелятивистских идей.
124837005
SEARCH FOR QUARKS WITH THE FERROMAGNETIC LEVITATION ELECTROMETER
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).
119592224
New Results in the Search of Quarks in Matter by the Magnetic Levitation Electrometer
Abstract The results of many runs performed levitating in succession several spheres without opening the levitation chamber show the existence of an additional (magneto-electric) force acting on the sphere. Ignoring this force in the analysis of the data produces “spurious” fractional charges.
120916653
The relation between QCD and constituent quark models
62825805
THE CLIC MACHINE PROTECTION
INTRODUCTION The proposed Compact Linear Collider (CLIC) [1, 2] is based on a two-beam acceleration scheme. The energy of two high-intensity, low-energy drive beams is extracted and transferred to the two low-intensity, high-energy main beams. The machine protection has to cope with a wide variety of failures, from real-time failures (RF breakdowns, kicker misfiring), to slow equipment failures, to beam instabilities (caused by e.g. temperature drifts, slow ground motions). Due to the many different types of accelerator components and the beams of various characteristics throughout the entire complex, the CLIC machine protection is an extensive subject. The machine protection has the mission to protect the various machine components from damage caused by ill controlled beams. The severity of the damage is given by the financial impact of the damage and the reduction in the operational availability of the facility. The risk equivalent is given by the product of the fault rate and the impact of the fault (i.e. in statistical terms: risk is the expectation value of the fault impact). This concept is illustrated by some examples for downtime in Table 1.