η_b decay into charmonium in association with c pair

We calculate the inclusive decay rates of ηb into charmonium via double c pairs for S-and P-wave states ηc,J/ψ and χcJ within the framework of non-relativistic QCD(NRQCD) factorization at leading order in αs.Besides calculating the contributions of the color-singlet channels ηb→c[2S+1SL(1)]+c,the effects of c pair in the color-octet configurations are also considered.We find that ηb→c[3S1(8)]+c make a small contribution to Br(ηb→J/ψ(ηc)+c).While in the ηb→χcJ+c case,the color octet contributions are significant,for they are of the same αs4vc5 order as the color-singlet processes.We predict Br(ηb→J/ψ(ηc)+c)=2.99(2.75)×10-5 for S-wave states J/ψ and ηc,and Br(ηb→χcJ+c)=(4.37,3.40,2.83)×10-5(for J =0,1,2) for P-wave states χcJ.In the end,we also find Br(ηb→ cc) is almost saturated by ηb decay into charmonium in association with c pair from the point of view of duality.     

ηb decay into charmonium in association with cc pair

We calculate the inclusive decay rates of ηb into charmonium via double c~ pairs for S- and P-wave states ηc, J/ψ and XcJ within the framework of non-relativistic QCD （NRQCD） factorization at leading order in αs. Besides calculating the contributions of the color-singlet channels ηb → cc[2s＋1SL^（1）]＋cc, the effects of cc pair in the color-octet configurations are also considered. We find that ηb → cc[3S1^（8）] ＋cc make a small contribution to Br（ηb →J/ψ（ηc）＋cc）. While in the ηb →XcJ ＋cc case, the color octet contributions are significant, for they are of the same a 5 order as the color-singlet processes. We predict Br（ηb →J/ψ（ηc）＋cc） = 2.99（2.75） × 10^-5 Vc for S-wave states J/ψ and ηc, and Br（ηb → XcJ ＋cc） = （4.37, 3.40, 2.83） × 10^-5 （for J = 0,1, 2） for P-wave states XcJ. In the end, we also find Br（ηb → cccc） is almost saturated by ηb decay into charmonium in association with cc pair from the point of view of duality.     

ηb decay into charmonium in association with c(c) pair

We calculate the inclusive decay rates of ηb into charmonium via double cc pairs for S- and P-wave states ηc, J/ψ and χcJ within the framework of non-relativistic QCD (NRQCD) factorization at leading order in αs. Besides calculating the contributions of the color-singlet channels ηb→c(c)[2S+1Sl(1)]+c(c), the effects of c(c) pair in the color-octet configurations are also considered. We find that ηb→c(c)[3S1(8)]+c(c) make a small contribution to Br(ηb→J/ψ(ηc)+c(c)). While in ther ηb→χcJ+c(c) case, the color octet contributions are significant, for they are of the same αs4vc5 order as the color-singlet processes. We predict Br(ηb → J/ψ(ηc)+c(c)) = 2.99(2.75) × 10-5 for S-vrave states J/ψ and ηc, and Br(ηb→χcJ +c(c))= (4.37,3.40,2.83)×10-5 (for J = 0,1,2) for P-wave states χcJ. In the end, we also find Br(ηb → c(c)c(c)) is almost saturated by ηb decay into charmonium in association with cc pair from the point of view of duality.     

Double Diffractive Process Factorization from ηc and γ Associated Production at Tevatron and LHC

We present a study of associated ηc and γ double diffractive production in pp^- collision based on Ingelman-Schlein model, and the framework of non-relativistic QOD factorization formalism for quarkonia production. The prediction of ηc and γ is more reliable than J/ψ production, because the associated ηc and γ production is a pure color-octet process, and the dominant contribution comes from color octet ^1S0^(8) subprocess, which is related to the color octet matrix element of ^1S0(8) of J/ψ by the heavy quark spin symmetry and the large PT J/ψ production data. We find that the ratio of diffractive to inclusive cross sections is independent of the values of color octet matrix elements, but is sensitive to the gluon factor of the Pomeron and renormalized Pomeron flux factors. So experimental measurement of this ratio can give us more information of the nature of Pomeron and test the assumption of hard diffractive factorization in hadron-hadron collisions.     

Inclusive Cross Section Production of J/ψ in LEP

Cross section production is one of the observable quantities in the hadronic systems. Inclusive cross section production J/ψ may be calculated through the use of the fragmentation c → J/ψ. In this paper we calculate the inclusive cross section production J/ψ about the pole of Z~0 in the e~+e~- annihilation, through the lowest order regim of perturbative of QCD ananlyticaly. The obtained results arrive an excellent agreement with the exprimental data to produce the inclusive cross section production c → J/ψ.     

Radiative Decays of Charmonium into Light Mesons

We apply perturbative QCD to the radiative decays of charmonia J/ψ and χcJ into light mesons. We perform a complete numerical calculation for the quark-gluon loop diagrams involved in these processes. The calculated J/ψ decay branching ratios into p-wave mesons f2（1270） and f1（1285） fit the data well, while that of fo（980） （if treated as an ss meson） is predicted to be 1.6×10^-4, which implies that f0（1710） can not be the ss or （uu＋dd）/√2 meson. Decays of p-wave charmonia χcJ→ρ（ω;φ）γ （J = 0, 1, 2） are also studied, and the branching ratio of χc1→ργ is predicted to be 1.4×10^-5, which may be tested by CLEO-c collaboration and BESlg collaboration with future experiments.     

Measurement of J/ψ→ηcγ at KEDR

We present a study of the inclusive photon spectra from 5.9 million J/ψ decays collected with the KEDR detector at the VEPP-4M e＋e collider. We measure the branching fraction of radiative decay J/ψ→ηcγ, ηc width and mass. Our preliminary results are： M（ηc） = 2979.4± 1.5 ± 1.9 MeV/c^2, Г（ηc） = 27.8±5.1 ±3.3 MeV, B（Jψ→ηcγ） = （2.34±0.15±0.40）%.     

J/ψ pair production at the Tevatron with s1/2=1.96 TeV

We study the J/ψ pair production issue at the Fermilab Tevatron Run II with a center-of-mass energy of s^1/2=1.96TeV. Both the color-singlet and color-octet production mechanisms are considered. Our results show that the transverse momentum （pT） scaling behaviors of the double J/ψ differential cross-sections in the color-singlets and color-octets deviate distinctively from each other while pT is larger than 8GeV, and with a luminosity of 5fb^-1 , the J/ψ pair events from the color-singlet scheme are substantially measurable in the Tevatron experiments, even with a certain lower transverse momentum cut. Hence the Tevatron is still a possible platform to check the heavy quarkonium production mechanism.     

Exploring J/ψ Production Mechanism at the Future Electron-Ion Collider

We propose to use transverse momentum p_T distribution of J/ψ production at the future Electron Ion Collider(EIC) to explore the production mechanism of heavy quarkonia in high energy collisions.We apply QCD and QED collinear factorization to the production of a cc pair at high p_T,and non-relativistic QCD factorization to the hadronization of the pair to a J/ψ.We evaluate J/ψ p_T-distribution at both leading and next-to-leading order in strong coupling,and show that production rates for various color-spin channels of a cc pair in electronhadron collisions are very different from that in hadron-hadron collisions,which provides a strong discriminative power to determine various transition rates for the pair to become a J/ψ.We predict that the J/ψ produced in electron-hadron collisions is likely unpolarized,and the production is an ideal probe for gluon distribution of colliding hadron(or nucleus).We find that the J/ψ production is dominated by the color-octet channel,providing an excellent probe to explore the gluon medium in large nuclei at the EIC.     

Helicity Amplitude Analysis of e^＋e^- ψ（2S） → γχcJ→γ∧∧^-→γpπ^-p^-π^＋＊

An analysis of the helicity amplitude is performed on the process e^＋e^- ψ（2S） → γχcJ→γ∧∧^-→γpπ^-p^-π^＋. The joint angular distributions for each decay chain are given, and we focus on discussing the E1 contributions to ψ（2S） radiative decays, and the violation of the helicity selection rule in χcJ decays into hyperon pairs, together with the possibility of observing parity violation in successive hyperon decays.     

Associated J/ψ γ production Through Color-Octed Mechanism in P Fe Collision

The contribution of color-octet heavy quarkonium production mechanism in P Fe→J/ψ γ X process is calculated and discussed.The results show that color-octedt contributions are rather large and sometimes can exceed the color-singlet contributions,Using the structure function of Fe given by double Q2-rescaling model,the influence of nuclear effect on this process is also studied.     

J/ψ pair production at the Tevatron with s=1.96 TeV

We study the m J/ψ pair production issue at the Fermilab Tevatron Run II with a center-of-mass energy of √s=1.96 TeV. Both the color-singlet and color-octet production mechanisms are considered. Our results show that the transverse momentum (p_T) scaling behaviors of the double m J/ψ differential cross-sections in the color-singlets and color-octets deviate distinctively from each other while p_T is larger than 8 GeV, and with a luminosity of 5 fb^-1, the m J/ψ pair events from the color-singlet scheme are substantially measurable in the Tevatron experiments, even with a certain lower transverse momentum cut. Hence the Tevatron is still a possible platform to check the heavy quarkonium production mechanism.     

Diffractive Scattering Factorization from J/ψ and γ Associated Production in HERA ep Collisions

Using three sets of Pomeron structure functions,the cross sections of J/ψ and γ associated production via resolved photon and proton diffractive scatting in ep collision are investigated.It is found that the cross sections calculated with various gluon distribution functions of Pomeron are different.The discrepancy is about 1.8 times for differential cross sections and 1.7 times for total cross sections.The experimental studies of the process could give valuable insight in the diffractive production mechanism and test the color-octet mechanism for heavy quarkonium production in a new environment.     

Diffractive Scattering Factorization from J/ψ and γ Associated Production in HERA ep Collisions

Using three sets of Pomeron structure functions, the cross sections of J/ψ and γ associated productionvia resolved photon and proton diffractive scatting in ep collision are investigated. It is found that the cross sectionscalculated with various gluon distribution functions of Pomeron are different. The discrepancy is about 1.8 times fordifferential cross sections and 1.7 times for total cross sections. The experimental studies of the process could give valuableinsight in the diffractive production mechanism and test the color-octet mechanism for heavy quarkonium production ina new environment.     

Semileptonic Decays of Bc Meson to a P—Wave Charmonium State χc or hc

The semileptonic decays of meson Bc to a P-wave charmonium state χc(3PJ) or hc(1P1)are computed.The results show that the decays are sizable so they are accessible in Tevatron and LHC,especially,with the detectors LHCB and BTeV in the foreseeable future,and of them,the one to the 1P1 charmonium state potentially offers us a novel window to see the unconfirmed hc particle.In addition,it is pointed out that since the two charmonium radiative decays χc (3P1,2)→J/ψ γ have sizable branching ratios,the cascade decays of the concerned decays and the charmonium radiative decays may affect the result of observing Bc meson through the semileptonic decays Bc→J/ψ l vl substantially.     

Helicity Amplitude Analysis of ηc Decays into Hyperon-Antihyperon Pairst

The helicity amplitudes for the processes of e^＋e^- →J/ψ→γηc→γYY（Y： hyperon） are presented, together with the joint angular distributions for ηc decays into ∧∧,∑^0 ∑^0, and [1]-[1]＋. The sensitivities to measure the hyperon decay parameters in these decays are evaluated based on the helicity amplitudes. The prospects to test the Bell inequality in experiment using the decay of ηc→∧∧ are discussed.     

Determination of J/ψ Event Number via J/ψ → μ^＋μ^- and J/ψ → e^＋e^- at BESⅢ

The decays of J/ψ → μ^＋μ^- and J/ψ → e^＋e^- are studied by Monte-Carlo simulation, based on the Beijing Spectrometer （BES）Ⅲ offtine software system. The methods of determination of the J/ψ event number via J/ψ → μ^＋μ^- and J/ψ → e^＋e^- are presented, respectively. These methods can be used to determine the J/ψ event number for the coming BESⅢ J/ψ data sample.     

Study of ππ final state interactions in ψ（2S） →π^＋π^-J/ψ

The π^＋π^ transition of heavy quarkonia in decay ψ（2S） →π^＋π^-J/ψ is studied. With the BESII data on the decay ψ（2S） →π^＋π^-J/ψ, we update the values of coupling constants （gi） and chromopolarizability （αψ（2s）J/ψ） in this process.     

Charmonium results from BES

Using ～ 14 × 10^6 ψ（2S） and ～ 58 × 10^ J/ ψ data collected at BES Ⅱ/BEPC, the branching fraction of ψ（2S）→Ω-Ω^＋ is measured with about 5a statistical significance. The A electric dipole and ∧ decay parameter are studied using the decay J/ψ →∧∧→ ppπ^＋π^-. Using （106±3）× 10^6 ψ（2S） decays collected at BESⅢ/BEPC Ⅱ, we have obtained some interesting physics results. The branching fractions of XcJ→π^0π^0, ηη are measured with precision improved. The mass and width of he（l^1P1） state, together with the branching fractions of Br（ψ（2S） →π^0hc） and Br（hc →γηc） are the first measurements. Surprisingly, the decays of Xc1→φφ, ωω, and ωφ are firstly observed in BESⅢ data.     

J/ψ Inclusive Photon Spectrum at BESⅢ

With a 15M J/ψ inclusive Monte Carlo sample, the absolute branching fraction of J/ψ→γη′ from the J/ψ inclusive photon spectrum is measured to be Br（J/ψ→γη′）= （4.68 ± 0.08± 0.27） × 10-3, which is in good agreement with the input value. The J/ψ→γfJ（2220） is also searched for using the same sample. Under our assumptions, the statistical significanees of J/ψ→γfJ（2220） are larger than 7σ.