scholarly journals Next-to-leading-order QCD corrections to a vector bottomonium radiative decay into a charmonium

2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
Yu-Dong Zhang ◽  
Feng Feng ◽  
Wen-Long Sang ◽  
Hong-Fei Zhang
Keyword(s):  
Decay Width ◽  
Radiative Decay ◽  
Branching Fraction ◽  
Branching Fractions ◽  
Leading Order ◽  
Good Opportunity ◽  
Decay Widths ◽  
Helicity Amplitudes ◽  
Order Of Magnitude ◽  
Theory And Experiment

Abstract Within the framework of nonrelativistic QCD (NRQCD) factorization, we calculate the next-to-leading-order (NLO) perturbative corrections to the radiative decay Υ → ηc(χcJ) + γ. Both the helicity amplitudes and the helicity decay widths are obtained. It is the first computation for the processes involving both bottomonium and charmonium at two-loop accuracy. By employing the Cheng-Wu theorem, we are able to convert most of complex-valued master integrals (MIs) into real-valued MIs, which makes the numerical integration much efficient. Our results indicate the $$ \mathcal{O}\left({\alpha}_s\right) $$ O α s corrections are moderate for ηc and χc2 production, and are quite marginal for χc0 and χc1 production. It is impressive to note the NLO corrections considerably reduce the renormalization scale dependence in both the decay widths and the branching fractions for χcJ, and slightly improve that for ηc. With the NRQCD matrix elements evaluated via the Buchmüller-Tye potential model, we find the decay width for ηc production is one-order-of-magnitude larger than χcJ production, which may provide a good opportunity to search for Υ → ηc + γ in experiment. In addition, the decay width for χc1 production is several times larger than those for χc0,2. Finally, we find the NLO NRQCD prediction for the branching fraction of Υ → χc1 + γ is only half of the lower bound of the experimental data measured recently by Belle. Moreover, there exists serious contradiction between theory and experiment for Υ → ηc + γ. The discrepancies between theory and experiment deserve further research efforts.

RADIATIVE DECAYS OF BARYONS IN A FIELD THEORETIC QUARK MODEL

1996 ◽  
Vol 11 (32) ◽  
pp. 5685-5700 ◽  
Author(s):  
A.R. PANDA ◽  
R.K. SAHOO
Keyword(s):  
Quark Model ◽  
Radiative Decay ◽  
Constituent Quark ◽  
Theoretical Calculations ◽  
Wave Functions ◽  
Radiative Decays ◽  
Quark Field ◽  
Decay Widths ◽  
Helicity Amplitudes ◽  
Decays Of Baryons

Radiative decays of baryons are considered in a field theoretic quark model of composite hadrons where the translationally invariant SU (6) hadron states are described by constituent quark field operators and harmonic oscillator wave functions. The constituent quark field operators of the model satisfying the equal time algebra are also Lorentz-boosted through a spin rotation to describe hadrons in motion. The model, like its earlier success in describing the different hadronic phenomena, in the present investigation without any free parameters, obtains the radiative decay widths and helicity amplitudes in reasonable agreement with other theoretical calculations as well as with the available experimental measurements.

scholarly journals Strong decays of heavy tensor mesons in QCD sum rules

2016 ◽  
Vol 31 (06) ◽  
pp. 1650036 ◽  
Author(s):  
Zhen-Yu Li ◽  
Zhi-Gang Wang ◽  
Guo-Liang Yu
Keyword(s):  
Decay Width ◽  
Sum Rules ◽  
Order Approximation ◽  
Coupling Constants ◽  
Leading Order ◽  
Strong Decay ◽  
Qcd Sum Rules ◽  
Consistent Description ◽  
Decay Widths ◽  
Tensor Formula

In this paper, the tensor–vector–pseudoscalar (TVP) type of vertices are analyzed with the QCD sum rules (QCDSR) and the local-QCD sum rules (SR) in the leading-order approximation and the hadronic coupling constants [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] together with the corresponding decay widths are then calculated. The results indicate that QCDSR as well as the local-QCDSR give a consistent description. The calculated strong decay widths and decay width ratios are compared with the available experimental and other theoretical values. Finally, the total widths [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] are discussed in detail. The results show that these total widths are underestimated, especially for the tensor [Formula: see text] and [Formula: see text] mesons where the obtained predictions are almost a factor of 2 lower than measured decay widths.

Electromagnetic properties of nonstrange Baryons in a nonrelativistic quark model

2017 ◽  
Vol 26 (07) ◽  
pp. 1750049 ◽  
Author(s):  
Zahra Ghalenovi ◽  
Masoumeh Moazzen
Keyword(s):  
Quark Model ◽  
Radiative Decay ◽  
Magnetic Moments ◽  
Theoretical Models ◽  
Branching Ratios ◽  
Electromagnetic Properties ◽  
Nonrelativistic Quark Model ◽  
Decay Widths ◽  
Helicity Amplitudes ◽  
Hyperspherical Approach

Masses and magnetic moments of [Formula: see text] and [Formula: see text] resonances are calculated employing the hyperspherical approach. We extend our scheme to obtain the helicity amplitudes and transition magnetic moments of the [Formula: see text] process. We also compute the radiative decay widths and branching ratios of [Formula: see text] baryons. A comparison of our results with the predictions obtained in recent theoretical models is also presented.

scholarly journals Angular analysis of $$ {B}^0\to {D}^{\ast -}{D}_s^{\ast +} $$ with $$ {D}_s^{\ast +}\to {D}_s^{+}\gamma $$ decays

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
◽  
R. Aaij ◽  
C. Abellán Beteta ◽  
T. Ackernley ◽  
B. Adeva ◽  
...  
Keyword(s):  
Helicity Amplitude ◽  
Branching Fraction ◽  
Branching Fractions ◽  
Centre Of Mass ◽  
Mass Energy ◽  
The Third ◽  
Angular Analysis ◽  
Helicity Conservation ◽  
Helicity Amplitudes ◽  
Cabibbo Suppressed

Abstract The first full angular analysis of the $$ {B}^0\to {D}^{\ast -}{D}_s^{\ast +} $$ B 0 → D ∗ − D s ∗ + decay is performed using 6 fb−1 of pp collision data collected with the LHCb experiment at a centre-of-mass energy of 13 TeV. The $$ {D}_s^{\ast +}\to {D}_s^{+}\gamma $$ D s ∗ + → D s + γ and D*− → $$ {\overline{D}}^0{\pi}^{-} $$ D ¯ 0 π − vector meson decays are used with the subsequent $$ {D}_s^{+} $$ D s + → K+K−π+ and $$ {\overline{D}}^0 $$ D ¯ 0 → K+π− decays. All helicity amplitudes and phases are measured, and the longitudinal polarisation fraction is determined to be fL = 0.578 ± 0.010 ± 0.011 with world-best precision, where the first uncertainty is statistical and the second is systematic. The pattern of helicity amplitude magnitudes is found to align with expectations from quark-helicity conservation in B decays. The ratio of branching fractions [ℬ($$ {B}^0\to {D}^{\ast -}{D}_s^{\ast +} $$ B 0 → D ∗ − D s ∗ + ) × ℬ($$ {D}_s^{\ast +}\to {D}_s^{+}\gamma $$ D s ∗ + → D s + γ )]/ℬ(B0 → D*−$$ {D}_s^{+} $$ D s + ) is measured to be 2.045 ± 0.022 ± 0.071 with world-best precision. In addition, the first observation of the Cabibbo-suppressed Bs → D*−$$ {D}_s^{+} $$ D s + decay is made with a significance of seven standard deviations. The branching fraction ratio ℬ(Bs → D*−$$ {D}_s^{+} $$ D s + )/ℬ(B0 → D*−$$ {D}_s^{+} $$ D s + ) is measured to be 0.049 ± 0.006 ± 0.003 ± 0.002, where the third uncertainty is due to limited knowledge of the ratio of fragmentation fractions.

scholarly journals New narrow nucleon resonances $N^{\ast}(1685)$ and $N^{\ast}(1726)$ within the chiral quark–soliton model

2019 ◽  
Vol 2019 (9) ◽  
Author(s):  
Ghil-Seok Yang ◽  
Hyun-Chul Kim
Keyword(s):  
Decay Width ◽  
Radiative Decay ◽  
Proton Channel ◽  
Radiative Decays ◽  
Baryon Octet ◽  
Soliton Model ◽  
Decay Modes ◽  
Nucleon Resonances ◽  
Decay Widths ◽  
The Masses

AbstractWe investigate the strong and radiative decay widths of the narrow nucleon resonances $N^*(1685)$ and $N^{\ast}(1726)$ within the framework of the SU(3) chiral quark–soliton model. All the relevant parameters are taken from those used to describe the properties of the baryon octet and decuplet in previous works. The masses of the antidecuplet nucleon and the eikosiheptaplet (27-plet) nucleon with spin 3/2 are determined respectively to be $(1690.2\pm 10.5)\, \mathrm{MeV}$ and $(1719.6\pm7.4)\,\mathrm{MeV}$. The decay width for $N^{\ast}(1685)\to \eta + N$ is found to be approximately three times larger than that for $N^{\ast}(1685)\to \pi + N$. The width of the decay $N^{\ast}\left(1726\right)3/2^+\to \eta + N$ is about 31 times larger than that of $N^{\ast}\left(1726\right)3/2^+\to \pi + N$. The ratio of the radiative decays for $N^*(1685)$ is obtained to be $\Gamma_{nn^*(1685)}/\Gamma_{pp^*(1685)}=8.62\pm3.45$, which explains very well the neutron anomaly. In contrast, we find $\Gamma_{pp^*(1726)}/\Gamma_{nn^*(1726)}=3.72\pm0.64$, which indicates that the production of $N^*(1726)$ is more likely to be observed in the proton channel. We also examine the decay modes of these narrow nucleon resonances with the strangeness hadrons involved.

The sircular polarization of γ-quanta in the radiative decay H Þ`ffγ (II)

2021 ◽  
pp. 134-141
Author(s):  
S.K. Abdullayev ◽  
◽  
E.Sh. Omarova ◽  
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Circular Polarization ◽  
Invariant Mass ◽  
Decay Width ◽  
Radiative Decay ◽  
W Boson ◽  
Decay Channel ◽  
Fermion Pair ◽  
The Standard Model

Within the framework of the Standard Model, the radiative decay channel of the Higgs boson into fermion-antifermion pair is investigated: H Þ` ff γ. Taking into account the fermion and W -boson loop diagrams an analytical expression for the decay width is obtained, the circular polarization of the γ-quanta is studied in dependence of the angle θ and invariant mass of the fermion pair.

Charmonia production in W → (cc̄)Ds(∗) decays

2021 ◽  
Vol 36 (09) ◽  
pp. 2150058
Author(s):  
A. V. Luchinsky ◽  
A. K. Likhoded
Keyword(s):  
Quantum Chromodynamics ◽  
Light Cone ◽  
Relativistic Quantum ◽  
Branching Fractions ◽  
Color Singlet ◽  
Leading Order ◽  
Paper Production ◽  
Quantum Numbers ◽  
Numerical Predictions ◽  
State Formula

In this paper, production of charmonium state [Formula: see text] in exclusive [Formula: see text] decays is analyzed in the framework of both leading order Non-relativistic Quantum Chromodynamics (NRQCD) and light-cone (LC) expansion models. Analytical and numerical predictions for the branching fractions of these decays in both the approaches are given. The typical value of the branching fractions is [Formula: see text][Formula: see text][Formula: see text] and it turns out that the LC results are significantly larger than NRQCD ones (approximately two or four times increase depending on the quantum numbers of the final particles), so the effect of internal quark motion should be taken into account. Some rough estimates of color-octet contributions are presented and it is shown that these contributions could be comparable with color-singlet results.

An estimate of the radiative decay width of the P11(1470)

1971 ◽  
Vol 1 (17) ◽  
pp. 707-708 ◽  
Author(s):  
R. E. Mickens
Keyword(s):  
Decay Width ◽  
Radiative Decay

scholarly journals MEASUREMENT OF $\mathcal{B}(J/\psi\to \eta_{{\rm c}}\gamma)$ AT KEDR

2011 ◽  
Vol 02 ◽  
pp. 188-192 ◽  
Author(s):  
◽  
V. M. MALYSHEV
Keyword(s):  
Line Shape ◽  
Radiative Decay ◽  
Branching Fraction ◽  
Photon Spectrum

We present a study of the inclusive photon spectrum from 6.3 million J/ψ decays collected with the KEDR detector at the VEPP-4M e+e- collider. We measure the branching fraction of the radiative decay J/ψ → ηcγ, ηc width and mass. Taking into account an asymmetric photon line shape we obtain: Mηc = (2978.1 ± 1.4 ± 2.0) MeV/c2, Γηc = (43.5 ± 5.4 ± 15.8) MeV, [Formula: see text].

scholarly journals Model-independent investigation of the RJ/ψ,ηc and ratios of decay widths of semileptonic Bc decays into a P-wave charmonium

2019 ◽  
Vol 34 (31) ◽  
pp. 1950195 ◽  
Author(s):  
Wei Wang ◽  
Ruilin Zhu
Keyword(s):  
Branching Fractions ◽  
Form Factors ◽  
P Wave ◽  
Experimental Measurements ◽  
Complementary Information ◽  
Independent Investigation ◽  
Lepton Flavor ◽  
Decay Widths ◽  
Model Independent ◽  
Standard Models

Experimental measurements of decay branching fractions of semitaunic and semimuonic [Formula: see text] into [Formula: see text] have challenged the lepton flavor universality in standard models with about two standard deviations. In this paper, we first investigate the unitary constraint on form factors of [Formula: see text] meson into [Formula: see text]-wave and [Formula: see text]-wave charmonium. Such constraint leads to the exploration of the [Formula: see text] and other ratios [Formula: see text], [Formula: see text], and [Formula: see text] in a model-independent way. These results together with future experimental measurements can be used to explore the lepton flavor universality in a more systematic way. In addition, we point out that the helicity-dependent ratios [Formula: see text] and [Formula: see text] can also provide complementary information.

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