scholarly journals Portrait of a colour octet

2014 ◽  
Vol 2014 (8) ◽  
Author(s):  
J. A. Aguilar-Saavedra
Keyword(s):  
Colour Octet

scholarly journals Colour-octet contributions to exclusive charmonium decays

1997 ◽  
Vol 392 (1-2) ◽  
pp. 198-206 ◽  
Author(s):  
Jan Bolz ◽  
Peter Kroll ◽  
Gerhard A. Schuler
Keyword(s):  
Colour Octet

scholarly journals Prompt $${J/\psi }$$-pair production at the LHC: impact of loop-induced contributions and of the colour-octet mechanism

2019 ◽  
Vol 79 (12) ◽  
Author(s):  
Jean-Philippe Lansberg ◽  
Hua-Sheng Shao ◽  
Nodoka Yamanaka ◽  
Yu-Jie Zhang
Keyword(s):  
Pair Production ◽  
Good Control ◽  
Distance Matrix ◽  
High Energy ◽  
Matrix Elements ◽  
Hadron Colliders ◽  
Long Distance ◽  
Gauge Invariant ◽  
Energy Hadron ◽  
Colour Octet

AbstractPrompt double-$$J/\psi $$J/ψ production at high-energy hadron colliders can be considered as a golden channel to probe double parton scatterings (DPS)—in particular to study gluon–gluon correlations inside the proton—and, at the same time, to measure the distribution of linearly-polarised gluons inside the proton. Such studies, however, require a good control of both single parton scatterings (SPS) and DPS in the respective regions where they are carried out. In this context, we have critically examined two mechanisms of SPS that may be kinematically enhanced where DPS are thought to be dominant, even though they are either at higher orders in the strong-coupling or velocity expansion. First, we have considered a gauge-invariant and infrared-safe subset of the loop-induced contribution via colour-singlet (CS) transitions. We have found it to become the leading CS SPS contributions at large rapidity separation, yet too small to account for the data without invoking the presence of DPS yields. Second, we have surveyed the possible colour-octet (CO) contributions using both old and up-to-date non-perturbative long-distance matrix elements (LDMEs). We have found that the pure CO yields crucially depend on the LDMEs. Among all the LDMEs we used, only two result into a visible modification of the NRQCD (CS+CO) yield, but only in two kinematical distributions measured by ATLAS, those of the rapidity separation and of the pair invariant mass. These modifications, however, do not impact the control region used for their DPS study.

scholarly journals Colour octet extension of 2HDM

2016 ◽  
Vol 31 (20n21) ◽  
pp. 1630033 ◽  
Author(s):  
German Valencia
Keyword(s):  
Colour Octet

In this paper we consider some aspects of the Manohar–Wise extension of the SM with a colour-octet electroweak-doublet scalar applied to 2HDM. We present theoretical constraints on the parameters of this extension to both the SM and the 2HDM and discuss related phenomenology at LHC.

scholarly journals Quarkonium Production: Velocity-Scaling Rules and Long-Distance Matrix Elements

1997 ◽  
Vol 12 (22) ◽  
pp. 3951-3963 ◽  
Author(s):  
Gerhard A. Schuler
Keyword(s):  
Heavy Quark ◽  
Bound States ◽  
Potential Model ◽  
Distance Matrix ◽  
Bound State ◽  
Matrix Elements ◽  
Long Distance ◽  
Quarkonium Production ◽  
Quark Potential ◽  
Colour Octet

The hierarchy of long-distance matrix elements (MEs) for quarkonium production depends on their scaling with the velocity v of the heavy quark in the bound state. Ranges for the velocities in various bound states and uncertainties of colour-singlet MEs are estimated in a quark-potential model. Different possibilities for the scaling with v of the MEs are discussed; they depend on the actual values of v and the QCD scale. As an application, J/ψ polarization in e+e- annihilation is discussed. The first non-perturbative estimates of colour-octet MEs are presented and compared with phenomenological determinations. Finally, various predictions of prompt quarkonium production at LEP are compared.

scholarly journals The Possibility of Meson-Lepton and Dilepton Resonances

1987 ◽  
Vol 40 (3) ◽  
pp. 283
Author(s):  
SR Choudhury ◽  
GC Joshi ◽  
BHJ McKellar ◽  
EW Vogt
Keyword(s):  
Experimental Data ◽  
Branching Ratios ◽  
Composite Model ◽  
Charged Leptons ◽  
Colour Octet

Recent hints in experimental data of a fJ.1T resonance at 429 MeV have led us to speculate about the possibility of meson-lepton and dilepton resonances. We show that the proposed fJ.7T resonance at 429 MeV is not in conflict with the muon g-2 measurements, and that it could be interpreted as a partner of the excited charged leptons possibly seen at CERN. Moreover, a composite model by Fritzsch and Mandelbaum predicts not only a flavour octet of meson-muon resonances of which this could be one, but also dilepton resonances which were suggested by Ramm as an explanation of the lobe structure in the fJ.7T data. The observed widths and branching ratios of the resonances can be interpreted to suggest that the colour-octet states are considerably smaller than the colour singlets.

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