scholarly journals Spin-dependent fragmentation functions of gluon splitting into heavy quarkonia considering three different scenarios

2015 ◽  
Vol 30 (32) ◽  
pp. 1550179 ◽  
Author(s):  
S. Mohammad Moosavi Nejad ◽  
Mahdi Delpasand
Keyword(s):  
Heavy Quark ◽  
Bound State ◽  
Heavy Quarkonia ◽  
Heavy Quarkonium ◽  
Heavy Quark Mass ◽  
Spin Singlet ◽  
Fragmentation Probability ◽  
Spin Triplet ◽  
Fragmentation Functions ◽  
Heavy Quark Pair

Heavy quarkonium production is a powerful implement to study the strong interaction dynamics and QCD theory. Fragmentation is the dominant production mechanism for heavy quarkonia with large transverse momentum. With the large heavy quark mass, the relative motion of the heavy quark pair inside a heavy quarkonium is effectively nonrelativistic and it is also well known that their fragmentation functions can be calculated in the perturbative QCD framework. Here, we analytically calculate the process-independent fragmentation functions for a gluon to split into the spin-singlet and spin-triplet [Formula: see text]-wave heavy quarkonia using three different scenarios. We will show that the fragmentation probability of the gluon into the spin-triplet bound-state is the biggest one.

scholarly journals Y(4260) and Y(4360) as mixed hadrocharmonium

2014 ◽  
Vol 29 (12) ◽  
pp. 1450060 ◽  
Author(s):  
Xin Li ◽  
M. B. Voloshin
Keyword(s):  
Heavy Quark ◽  
Reasonable Agreement ◽  
Light Quark ◽  
Spin Symmetry ◽  
Final States ◽  
Quark Spin ◽  
Spin Singlet ◽  
Heavy Quark Spin Symmetry ◽  
Spin Triplet ◽  
Heavy Quark Pair

Recent BESIII data indicate a significant rate of the process e+e- →hc π+ π- at the Y(4260) and Y(4360) resonances, implying a substantial breaking of the heavy quark spin symmetry. We consider these resonances within the picture of hadrocharmonium, i.e. of (relatively) compact charmonium embedded in a light-quark mesonic excitation. We suggest that the resonances Y(4260) and Y(4360) are a mixture, with mixing close to maximal, of two states of hadrochamonium, one containing a spin-triplet [Formula: see text] pair and the other containing a spin-singlet heavy quark pair. We argue that this model is in a reasonable agreement with the available data and produces distinctive and verifiable predictions for the energy dependence of the production rate in e+e- annihilation of the final states J/ψππ, ψ′ππ and hc ππ, including the pattern of interference between the two resonances.

scholarly journals Power expansion for heavy quarkonium production at next-to-leading order in e+e− annihilation

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Kyle Lee ◽  
George Sterman
Keyword(s):  
Heavy Quark ◽  
Dimensional Regularization ◽  
Heavy Quarkonium ◽  
Group Equation ◽  
Leading Order ◽  
Energy Fraction ◽  
Analytical Results ◽  
Quarkonium Production ◽  
Fragmentation Functions ◽  
Heavy Quark Pair

Abstract We study heavy quarkonium production associated with gluons in e+e− annihilation as an illustration of the perturbative QCD (pQCD) factorization approach, which incorporates the first nonleading power in the energy of the produced heavy quark pair. We show how the renormalization of the four-quark operators that define the heavy quark pair fragmentation functions using dimensional regularization induces “evanescent” operators that are absent in four dimensions. We derive closed forms for short-distance coefficients for quark pair production to next-to-leading order ($$ {\alpha}_s^2 $$ α s 2 ) in the relevant color singlet and octet channels. Using non-relativistic QCD (NRQCD) to calculate the heavy quark pair fragmentation functions up to v4 in the velocity expansion, we derive analytical results for the differential energy fraction distribution of the heavy quarkonium. Calculations for $$ {}^3{S}_1^{\left[1\right]} $$ 3 S 1 1 and $$ {}^1{S}_0^{\left[8\right]} $$ 1 S 0 8 channels agree with analogous NRQCD analytical results available in the literature, while several color-octet calculations of energy fraction distributions are new. We show that the remaining corrections due to the heavy quark mass fall off rapidly in the energy of the produced state. To explore the importance of evolution at energies much larger than the mass of the heavy quark, we solve the renormalization group equation perturbatively to two-loop order for the $$ {}^1{S}_0^{\left[8\right]} $$ 1 S 0 8 case.

scholarly journals DOUBLE PARTON FRAGMENTATION FUNCTION AND ITS EVOLUTION IN QUARKONIUM PRODUCTION

2014 ◽  
Vol 25 ◽  
pp. 1460040
Author(s):  
ZHONG-BO KANG
Keyword(s):  
Fragmentation Function ◽  
Evolution Equations ◽  
Heavy Quarkonia ◽  
Large Transverse Momentum ◽  
Heavy Quark Mass ◽  
Qcd Factorization ◽  
Factorization Formalism ◽  
Quarkonium Production ◽  
Large Enhancement ◽  
Fragmentation Functions

We summarize the results of a recent study on a new perturbative QCD factorization formalism for the production of heavy quarkonia of large transverse momentum pT at collider energies. Such a new factorization formalism includes both the leading power (LP) and next-to-leading power (NLP) contributions to the cross section in the [Formula: see text] expansion for heavy quark mass mQ. For the NLP contribution, the so-called double parton fragmentation functions are involved, whose evolution equations have been derived. We estimate fragmentation functions in the non-relativistic QCD formalism, and found that their contribution reproduce the bulk of the large enhancement found in explicit NLO calculations in the color singlet model. Heavy quarkonia produced from NLP channels prefer longitudinal polarization, in contrast to the single parton fragmentation function. This might shed some light on the heavy quarkonium polarization puzzle.

An approach to heavy quarkonium spectra

2014 ◽  
Vol 29 (32) ◽  
pp. 1450170 ◽  
Author(s):  
Y. Cançelik ◽  
B. Gönül
Keyword(s):  
Eigenvalue Problem ◽  
Coulomb Potential ◽  
Mass Spectra ◽  
Bound State ◽  
Considerable Effect ◽  
Heavy Quarkonia ◽  
Heavy Quarkonium ◽  
Related Literature ◽  
Exactly Solvable ◽  
Math Phys

An application of the recently introduced method [M. Çapak et al., J. Math. Phys. 52, 102102 (2011)] to the bound-state eigenvalue problem in the elementary quarkonium potential V(r) = -a/r + br + cr2 is described, proved and illustrated for [Formula: see text] and [Formula: see text] systems. The quasi- and conditionally-exactly solvable spin-averaged mass spectra of heavy quarkonia are obtained in compact forms. The comparison of the present predictions with those of other theories in the related literature, together with the available data, has shown the success of the model used in this work and also revealed that the use of different confinings in the perturbed Coulomb potential descriptions has no considerable effect on the mass spectra of such systems.

BOUND STATE AND RADIATIVE CORRECTIONS TO HEAVY QUARK FRAGMENTATION FUNCTIONS

1995 ◽  
Vol 10 (13n14) ◽  
pp. 1019-1026
Author(s):  
M.A. GOMSHI NOBARY
Keyword(s):  
Experimental Data ◽  
Heavy Quark ◽  
Bound State ◽  
Radiative Corrections ◽  
Gluon Radiation ◽  
Initial State ◽  
Quark Fragmentation ◽  
Theoretical Predictions ◽  
Fragmentation Functions ◽  
Theory And Experiment

We comment on heavy quark fragmentation models motivated by QCD and study the influence of bound state and radiative corrections on heavy quark fragmentation emphasizing the comparison between the theoretical predictions and experimental data. It seems that meson constituents internal motion and initial state QCD gluon radiation may have a kinematical role in improving the agreement between theory and experiment. These effects are more striking in the case of charm fragmentation.

scholarly journals NONRELATIVISTIC QUARK–ANTIQUARK POTENTIAL: SPECTROSCOPY OF HEAVY-QUARKONIA AND EXOTIC SUSY QUARKONIA

2009 ◽  
Vol 24 (28n29) ◽  
pp. 5341-5362 ◽  
Author(s):  
SAMEER M. IKHDAIR ◽  
RAMAZAN SEVER
Keyword(s):  
Heavy Quark ◽  
Bound States ◽  
Expansion Method ◽  
Experimental Spectrum ◽  
Center Of Gravity ◽  
Heavy Quarkonia ◽  
Large N ◽  
Full Knowledge ◽  
Spin Triplet ◽  
Static Quark

The experiments at LHC have shown that the SUSY (exotic) bound states are likely to form bound states in an entirely similar fashion as ordinary quarks form bound states, i.e. quarkonium. Also, the interaction between two squarks is due to gluon exchange which is found to be very similar to that interaction between two ordinary quarks. This motivates us to solve the Schrödinger equation with a strictly phenomenological static quark–antiquark potential: [Formula: see text] using the shifted large N-expansion method to calculate the low-lying spectrum of a heavy quark with antisbottom [Formula: see text] and sbottom with antisbottom [Formula: see text] bound states with [Formula: see text] is set free. To have a full knowledge on spectrum, we also give the result for a heavier as well as for lighter sbottom masses. As a test for the reliability of these calculations, we fix the parameters of this potential by fitting the spin-triplet (n3S1) and center-of-gravity l≠0 experimental spectrum of the ordinary heavy quarkonia [Formula: see text], [Formula: see text] and [Formula: see text] to few MeV. Our results are compared with other models to gauge the reliability of these predictions and point out differences.

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