Is the up-quark massless?

Irving, A.C.; McNeile, Craig; Michael, C; Sharkey, Kieran J.; Wittig, Hartmut

doi:10.1016/s0370-2693(01)01062-0

Cited by 28 publications

(21 citation statements)

References 34 publications

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“…[1] that in lattice QCD (LQCD) with mass degenerate SU f (2) doublets of Wilson fermions it is possible to improve the approach to the continuum limit of correlation functions of gauge invariant multiplicative renormalizable (m. To avoid the difficulties related to the nature of the spectrum of the Wilson-Dirac (WD) operator (here we are referring to the well-known problem of the existence of "exceptional configurations" [2,3]) twisted-mass lattice QCD (tm-LQCD) [4] should be used for the actual com- * Talk presented by G.C. Rossi.…”

Section: Introductionmentioning

confidence: 99%

Twisted-mass lattice QCD with mass non-degenerate quarks

Frezzotti¹,

Rossi²

2004

Nuclear Physics B - Proceedings Supplements

214

312

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The maximally twisted lattice QCD action of an SU f (2) doublet of mass degenerate Wilson quarks gives rise to a real positive fermion determinant and it is invariant under the product of standard parity times the change of sign of the coefficient of the Wilson term. The existence of this spurionic symmetry implies that O(a) improvement is either automatic or achieved through simple linear combinations of quantities taken with opposite external three-momenta. We show that in the case of maximal twist all these nice results can be extended to the more interesting case of a mass non-degenerate quark pair.

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Section: Introductionmentioning

confidence: 99%

Twisted-mass lattice QCD with mass non-degenerate quarks

Frezzotti¹,

Rossi²

2004

Nuclear Physics B - Proceedings Supplements

214

312

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“…(The run where the reweighting was not completely negligible has the index (i).) Of course, at very small quark masses P (2) n2 becomes good enough only for a very large order n 2 . In such a case it is a question whether it would be more advantageous to keep n 2 smaller and tolerate a non-trivial reweighting.…”

Section: Analysis With Correction Factorsmentioning

confidence: 99%

“…It is taken into account in the updates by a global noisy Metropolis correction step. Since for fixed n 2 (and outside the interval [ǫ, λ]) the approximation P (1) P (2) is not exact, a final correction step is performed by reweighting the gauge configurations which are considered for the evaluation of the expectation values. This is done with a sufficiently high order polynomial P (2) n4 .…”

Section: Algorithmmentioning

confidence: 99%

“…The importance of the final correction step by the reweighting factors depends on the choice of the second polynomial P (2) . For good enough P (2) the reweighting is negligible.…”

Section: Analysis With Correction Factorsmentioning

confidence: 99%

“…This question has attracted a considerable attention in the last few years [1,2,3]. However, existing unquenched simulations are typically done in a region where the light quarks are not light enough, in most cases -especially with Wilson-type quarks -with two light quark flavours (u and d) having masses larger than half of the strange quark mass (m ud > 1 2 m s ).…”

Section: Introductionmentioning

confidence: 99%

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Lattice QCD with light dynamical quarks

Farchioni¹,

Gebert

Montvay

et al. 2003

Nuclear Physics B - Proceedings Supplements

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We report on the simulation of QCD with light dynamical quarks using the two-step multi-boson (TSMB) algorithm. In an exploratory study with two flavours of quarks at lattice spacing about 0.27 fm and with quark mass down to one sixth of the strange quark mass eigenvalue spectra and autocorrelations have been studied. Here we present results on the volume dependence as well as tests of possible algorithmic improvements.

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QCD Axion and Quintessential Axion

Kim

2004

Beyond the Desert 2003

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Abstract. The axion solution of the strong CP problem is reviewed together with the other strong CP solutions. We also point out the quintessential axion(quintaxion) whose potential can be extremely flat due to the tiny ratio of the hidden sector quark mass and the intermediate hidden sector scale. The quintaxion candidates are supposed to be the string theory axions, the model independent or the model dependent axions. The Strong CP ProblemAt this conference, the organizer asked to review on the axion [1] as the CDM candidate [2]. Therefore, I will review the QCD axion and the related problem, the strong CP problem. With supersymmetrization, an O(GeV) axino can be a CDM candidate also [3] in addition to the axion CDM, but we will not discuss this interesting class of CDM candidate here. It was reviewed in another DM conference [4]. Out of several CDM candidates, the axion is most attractive since it arises from the need to solve the strong CP problem. One crucial difference of the axion CDM from most other CDM candidates is that the axion is a classical field oscillation [2] while many other CDM candidates rely on their heavy particle nature. The classical axion potential is extremely flat as shown in Fig. 1. The axion value a stays at some point(the bullet) for a long time before it starts to oscillates, which occurs at T ≃ 1 GeV when the Hubble time 1/H becomes larger than the oscillation period m a .◮ < a >

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Is the up-quark massless?

Cited by 28 publications

References 34 publications

Twisted-mass lattice QCD with mass non-degenerate quarks

Twisted-mass lattice QCD with mass non-degenerate quarks

Lattice QCD with light dynamical quarks

QCD Axion and Quintessential Axion

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