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Topic: Quenched approximation

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	QCD matter - Wikipedia, the free encyclopedia
		One such is the quenched approximation, where all quark masses are taken to be infinite.
		In such this approximation, quarks do not take part in the dynamics, but the transition from confinement to deconfinement can be easily studied.
		A fairly new approximation is to adjoint to QCD other particles which are related to quarks by supersymmetry.
	en.wikipedia.org /wiki/QCD_matter (901 words)

	[No title]
		Thus we have (1.1) f_Ds = 240(10)(15) MeV, Nf=0 (quenched approximation), where the first error is Gaussian (statistics, extrapolation), and the second (flat) error reflects the quenching error due to the scale ambiguity.
		Dynamical simulations usually report an increase in the estimates for decay constants, but are not yet as mature as the quenched calculations.
		The quoted error is thus a convolution of different effects, such as statistics, discretisation & quenching effects, etc. In order to obtain the result for Nf=2, I combine (2.1) with (1.2), which gives (2.2) f_Bs = 220(25) MeV, Nf=2, where the error is the combination of the uncertainties in (1.2) and (2.1).
	www.hep.phys.soton.ac.uk /lwg-bmix/wittig_summary.txt (745 words)

	ERPUS: LANL Collaboration
		Because of various approximations that have to be made, this goal has yet to be attained.
		In the quenched approximation the quark-antiquark component of this cloud is ignored.
		This approximation is made in order that the large systems can be studied with present computer resources: the cost of removing the approximation is roughly two to four orders of magnitude.
	www.physics.ohio-state.edu /~kilcup/erpus (3022 words)

	Physics Papers
		In the dilute instanton gas model of the QCD vacuum, one expects a strong spatial correlation between chirality and the maxima of the Dirac eigenvectors with small eigenvalues.
		Quenched QCD simulations on three volumes, $8^3 \times$, $12^3 \times$ and $16^3 \times 32$ and three couplings, $\beta=5.7$, 5.85 and 6.0 using domain wall fermions provide a consistent picture of quenched QCD.
		Important effects of topological near zero modes which should afflict an accurate quenched calculation are easily visible in both the chiral condensate and the pion propagator.
	phys.columbia.edu /~cqft/physics_papers.htm (1894 words)

	Fermion Loop Corrections to Lattice QCD (Site not responding. Last check: 2007-08-08)
		In the quenched approximation of QCD, the expectation value of some quantity X is given by
		it is hoped to generate one fermion loop corrections over the quenched case.
		The plan is to implement the above technology on a set of M's that have been generated using a quenched weight, and hence calculate corrections to various observables.
	www.ph.unimelb.edu.au /~jfm/cv/phd_summary/node2.html (112 words)

	The generating functional for hadronic weak interactions and its quenched approximation
		= 1,2 hadronic weak interactions at one loop for a generic number of flavours and its counterpart in the quenched approximation.
		A systematic analysis of the ultraviolet divergences in the full theory (with and without a singlet dynamical field) and in the quenched case is performed.
		We show that the quenched chiral logarithms in the presence of weak interactions amount to a redefinition of the weak mass term in the ΔS = ±1 weak effective Lagrangian at leading order.
	stacks.iop.org /1126-6708/1999/i=01/a=012 (323 words)

	Journal Club January 17, 1997 (Site not responding. Last check: 2007-08-08)
		We present estimates of the masses of light quarks using lattice data.
		Our main results are based on a global analysis of all the published data for Wilson, Sheikholeslami-Wohlert (clover), and staggered fermions, both in the quenched approximation and with $n_f=2$ dynamical flavors.
		We find that the values of masses with the various formulations agree after extrapolation to the continuum limit for the $n_f=0$ theory.
	www.physics.ohio-state.edu /~anton/html/Abstract/970117.html (212 words)

	Southampton HPC Centre - GBIS - Benchmark Header File
		Conjugate gradient methods form the core of several important algorithms for lattice gauge theory with fermions.
		Supercomputer performance is essential for such problems as the inclusion of dynamical fermions increases the computational effort required by several orders of magnitude over the 'quenched' approximation.
		(The quenched approximation is used in the QCD1 benchmark) Simulations are defined on four-dimensional lattices which are discrete approximations to continuum space-time.
	www.netlib.org /parkbench/gbis/html/descriptions/qcd2.html (721 words)

	Derek Leinweber's Ongoing Research and Proposals (Site not responding. Last check: 2007-08-08)
		These new actions hold the promise of finally moving beyond the quenched approximation in a quantitative sense.
		While the often-used quenched approximation of lattice QCD eliminates the explicit calculation of sea-quark loops which interact with the valence quarks via gluon exchange, one can also consider a ``valence'' approximation which eliminates both sea and cloud quarks.
		The latter include antiquarks whose origin are in the Z-graphs of the quark lines carrying the quantum numbers of the nucleon.
	www.physics.adelaide.edu.au /~dleinweb/ResProp.html (1523 words)

	4.3.8 Status and Prospects (Site not responding. Last check: 2007-08-08)
		Already there have been some nice results in the context of the quenched approximation, but the lattices are still too coarse and too small to give definitive results.
		Reasonable results for the phenomenologically interesting physical observables should be available within the quenched approximation in the mid-1990s.
		With the same computer power, we will be able to redo today's quenched calculations using dynamic fermions (but still on today's size of lattice).
	www.netlib.org /utk/lsi/pcwLSI/text/node41.html (268 words)

	Citebase - Light Quark Masses from Lattice QCD
		The renormalization factor relating the bare to the renormalization group invariant quark masses is accurately calculated in quenched lattice QCD using a recursive finite-size technique.
		We show that most of the large dependence on the lattice spacing, a, observed in previous determinations using Wilson fermions is removed with the use of an O(a) corrected action.
		In the quenched approximation, we obtain for the stran
	www.citebase.org /cgi-bin/citations?id=oai:arXiv.org:hep-lat/9605039 (1444 words)

	Citebase - Non-perturbative Renormalization Constants using Ward Identities
		We determine the renormalization group invariant quark mass corresponding to the sum of the strange and the average light quark mass in the quenched approximation of QCD, using as essential input the mass of the K-mesons.
		The decay constants of B, D and K mesons are computed in quenched lattice QCD at two different values of the coupling.
		By imposing axial and vector Ward identities for flavour-non-singlet currents, we estimate in the quenched approximation the non-perturbative values of combinations of improvement coefficients, which appear in the expansion around the massless case of the renormalization constants of axial, pseudo...
	www.citebase.org /cgi-bin/citations?id=oai:arXiv.org:hep-lat/9904011 (1046 words)

	[No title]
		Golterman, ``Chiral Perturbation Theory for the Quenched Approximation of QCD,'' Phys.
		C. Bernard and M. Golterman, ``The Quenched Approximation in Health and in Sickness,'' Nucl.
		Sharpe, and A. Ukawa, ``Pion-pion Scattering in the Quenched Approximation,'' Nucl.
	www.physics.wustl.edu /~cb/pub/pub.html (4377 words)

	UCSB Physics: Numerical Studies of Field Theory
		Among recent projects have been studies of the mass spectrum of strongly interacting particles, the weak decays of these particles, and the properties of strongly interacting matter at high temperatures.
		"The continuum Limit in the Quenched Approximation" (with C. Bernard, T. Blum, C. DeTar, S. Gottlieb, U.M. Heller, J. Hetrick, K. Rummukainen, D. Toussaint, and M. Wingate) Nucl.
		"f B Quenched and Unquenched" (with C. Bernard, T. Blum, A. De, T. DeGrand, C. DeTar, S. Gottlieb, U.M. Heller, J. Hetrick, N. Ishizuka, J. Labrenz, K. Rummukainen, A. Soni, D. Toussaint, and M. Wingate) Nucl.
	www.physics.ucsb.edu /Research/activities/nsft.php3 (188 words)

	Fermilab Lattice Gauge Theory Computational Facility
		A recent Physical Review Letter, High Precision Lattice QCD Confronts Experiment, showed that the simplest lattice calculations, which agreed only at the 10% level in the quenched approximation, agree to a few per cent in the new calculations.
		They are accurately measurable in experiment, with good prototype calculations existing in the quenched approximation.
		Many of the lattice calculations most important to particle physics, such as the calculations required for understanding Bs Bs bar oscillations in the Tevatron, are in this family.
	lqcd.fnal.gov /physics.html (255 words)

	Cluster extension of the effective-interaction approximation. I. Quenched-bond disorder in the Ising model
		A systematic cluster extension of the effective-interaction approximation for quenched-bond disorder in random Ising systems is proposed.
		For bond dilution, exact results for the critical concentrations are obtained in the single-bond approximation for the self-dual square lattice and in the three-bonds approximation for the dual triangular and honeycomb lattices.
		Qualitative changes in the critical line are observed in the frustration model when going from the single-bond to the three-bonds approximations.
	stacks.iop.org /0022-3719/13/4077 (209 words)

	Energy Citations Database (ECD) - Energy and Energy-Related Bibliographic Citations
		Energy Citations Database (ECD) Document #7017075 - Problems with the quenched approximation in the chiral limit
		Availability information may be found in the Availability, Publisher, Research Organization, Resource Relation and/or Author (affiliation information) fields and/or via the "Full-text Availability" link.
		Problems with the quenched approximation in the chiral limit
	www.osti.gov /energycitations/product.biblio.jsp?osti_id=7017075 (90 words)

	[No title] (Site not responding. Last check: 2007-08-08)
		Calculation of $K\rightarrow \pi$ matrix elements in quenched domain-wall QCD
		matrix elements using domain-wall QCD within the quenched approximation.
		We carefully investigate how well "eye diagrams" can be evaluated by the
	t8web.lanl.gov /LAT00/abstract/15181 (80 words)

	[No title]
		and 2-colour QCD at finite mu, considered above, which have positive fermion determinants, the quenched approximation makes sense, unlike the case of QCD at finite mu
		We have studied both these theories in the quenched approximation and find that they do undergo a phase transition at the expected value of the chemical potential, to a superfluid state.
		shows the pion condensate for quenched QCD at finite mu
	www.hep.anl.gov /dks/NERSC2002/thermodynamics.html (1327 words)

	[No title]
		Joint Theory Seminar of VUB-ULB-KUL at Brussels, Belgium, Brout-Englert-Higgs Mechanism for Gravity and Higher Spin Fields, Nov 2005
		Stanford Linear Accelerator Center (SLAC): Holography of flavor beyond the quenched approximation, Oct 2005
		Poster (Strings 2005, Toronto): AdS/CFT with Flavor -- The quenched approximation and beyond, July 2005
	schwinger.harvard.edu /~ikirsch (175 words)

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