Soft, collinear, and nonrelativistic modes in radiative decays of very heavy quarkonium

Tormo, Xavier Garcia i; Soto, Joan

doi:10.1103/physrevd.69.114006

Cited by 24 publications

(26 citation statements)

References 54 publications

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“…They have so far either been ignored [10] or estimated to be small [11] in the available extractions of α s from this ratio. In this paper we take into account recent determinations of the Υ(1S) color octet matrix elements both on the lattice [12] and in the continuum [13], which indicate that their contribution is actually not small. This, together with the good theoretical description of the photon spectrum [9], allows for a consistent extraction of α s (M Υ(1S) ) at NLO in the NRQCD velocity counting.…”

Section: Introductionmentioning

confidence: 99%

Extraction ofαsfrom radiativeΥ(1S)decays

et al. 2007

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Section: Introductionmentioning

confidence: 99%

Extraction ofαsfrom radiativeΥ(1S)decays

et al. 2007

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“…In a recent series of papers the differential decay rate for the decay Υ → γX has been studied in the "endpoint" region where the decay products have a large total energy of order the Υ mass (M Υ ), and a small total invariant mass squared of order ΛM Υ , where Λ ∼ 1 GeV is the typical hadronic scale [1,2,3,4,5]. An important tool in this analysis is the softcollinear effective theory (SCET) [6,7,8,9], which is a systematic treatment of the high energy limit of QCD in the framework of effective field theory.…”

Section: Introductionmentioning

confidence: 99%

Exclusive radiative decays ofΥin soft-collinear effective theory

2005

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We study exclusive radiative decays of the Υ using soft-collinear effective theory and nonrelativistic QCD. In contrast to inclusive radiative decays at the endpoint we find that color-octet contributions are power suppressed in exclusive decays, and can safely be neglected, greatly simplifying the analysis. We determine the complete set of Lorentz structures that can appear in the SCET Wilson coefficients and match onto them using results from a previous calculation. We run these coefficients from the scale M Υ to the scale Λ ∼ 1 GeV, thereby summing large logarithms. Finally we use our results to predict the ratio of branching fractions B(Υ → γf 2 )/B(J/ψ → γf 2 ), B(J/ψ → γf 2 )/B(ψ ′ → γf 2 ), and the partial rate for Υ → γππ.

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“…The recent lattice [233] and continuum [234] estimates of the octet matrix elements are used to obtain this result. Table 25).…”

Section: αS Determinationsmentioning

confidence: 99%

Heavy quarkonium: progress, puzzles, and opportunities

Brambilla¹,

Eidelman²,

Heltsley³

et al. 2011

Advances in the Physics of Particles and Nuclei

103

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A golden age for heavy quarkonium physics dawned a decade ago, initiated by the confluence of exciting advances in quantum chromodynamics (QCD) and an explosion of related experimental activity. The early years of this period were chronicled in the Quarkonium Working Group (QWG) CERN Yellow Report (YR) in 2004, which presented a comprehensive review of the status of the field at that time and provided specific recommendations for further progress. However, the broad spectrum of subsequent breakthroughs, surprises, and continuing puzzles could only be partially anticipated. Since the release of the YR, the BESII program concluded only to give birth to BESIII; the B-factories and CLEO-c flourished; quarkonium production and polarization measurements at HERA and the Tevatron matured; and heavy-ion collisions at RHIC have opened a window on the deconfinement regime. All these experiments leave legacies of quality, precision, and unsolved mysteries for quarkonium physics, and therefore beg for continuing investigations at BESIII, the LHC, RHIC, FAIR, the Super Flavor and/or Tau-Charm factories, JLab, the ILC, and beyond. The list of newly-found conventional states expanded to include hc(1P ), χc2(2P ), B + c , and η b (1S). In addition, the unexpected and still-fascinating X(3872) has been joined by * Editors † Section coordinators ‡ Corresponding author: bkh2@cornell.edu more than a dozen other charmonium-and bottomonium-like "XY Z" states that appear to lie outside the quark model. Many of these still need experimental confirmation. The plethora of new states unleashed a flood of theoretical investigations into new forms of matter such as quark-gluon hybrids, mesonic molecules, and tetraquarks. Measurements of the spectroscopy, decays, production, and in-medium behavior of cc, bb, and bc bound states have been shown to validate some theoretical approaches to QCD and highlight lack of quantitative success for others. Lattice QCD has grown from a tool with computational possibilities to an industrialstrength effort now dependent more on insight and innovation than pure computational power. New effective field theories for the description of quarkonium in different regimes have been developed and brought to a high degree of sophistication, thus enabling precise and solid theoretical predictions. Many expected decays and transitions have either been measured with precision or for the first time, but the confusing patterns of decays, both above and below open-flavor thresholds, endure and have deepened. The intriguing details of quarkonium suppression in heavy-ion collisions that have emerged from RHIC have elevated the importance of separating hotand cold-nuclear-matter effects in quark-gluon plasma studies. This review systematically addresses all these matters and concludes by prioritizing directions for ongoing and future efforts.

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Soft, collinear, and nonrelativistic modes in radiative decays of very heavy quarkonium

Cited by 24 publications

References 54 publications

Extraction ofαsfrom radiativeΥ(1S)decays

Extraction ofαsfrom radiativeΥ(1S)decays

Exclusive radiative decays ofΥin soft-collinear effective theory

Heavy quarkonium: progress, puzzles, and opportunities

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