phenomenological parameter
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2020 ◽  
Vol 35 (19) ◽  
pp. 2050093
Author(s):  
Behnam Mohammadi

In this paper the decays of [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] have been investigated. The available experimental results for these decays are (in units of [Formula: see text]): [Formula: see text] By applying the theoretical value of the [Formula: see text] that span the range of [Formula: see text], the results for QCDF approach are about [Formula: see text] times smaller than experimental one. Therefore, it is decided to calculate the theoretical branching ratio by applying the final state interaction (FSI) through the [Formula: see text] (crossed and uncrossed) channels. The FSI effects are very sensitive to the changes in the phenomenological parameter [Formula: see text]. This parameter appears in the FSI form factors that increase strong interaction share. In most calculation changing two units in this parameter, makes the final result multiply in the branching ratio, therefore the decision to use FSI is not unexpected. In this study there are thirteen intermediate states for [Formula: see text] decay, fifteen intermediate states for [Formula: see text] decay and four intermediate states for [Formula: see text] and [Formula: see text] decays, in which the contribution of each one is calculated and summed in the final amplitude. Considering [Formula: see text] and fixing [Formula: see text] between four and five acceptable results have been obtained.


Symmetry ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 585 ◽  
Author(s):  
Eleonora Di Valentino ◽  
Sarah Bridle

This paper provides a snapshot of the formal S 8 ≡ σ 8 Ω m / 0.3 tension between Planck 2015 and the Kilo Degree Survey of450 deg 2 of imaging data (KiDS-450) or the Canada France Hawaii Lensing Survey (CFHTLenS). We find that the Cosmic Microwave Bckground (CMB) and cosmic shear datasets are in tension in the standard Λ Cold Dark Matter ( Λ CDM) model, and that adding massive neutrinos does not relieve the tension. If we include an additional scaling parameter on the CMB lensing amplitude A l e n s , we find that this can put in agreement the Planck 2015 with the cosmic shear data. A l e n s is a phenomenological parameter that is found to be more than 2 σ higher than the expected value in the Planck 2015 data, suggesting an higher amount of lensing in the power spectra, not supported by the trispectrum analysis.


2015 ◽  
Vol 30 (36) ◽  
pp. 1550222
Author(s):  
Amin Asadi ◽  
Hossein Mehraban

In this paper, we analyzed the decay [Formula: see text] within QCD factorization (QCDF) and final state interaction (FSI) methods. At first, we consider the QCDF approach, where the final states are a pseudoscalar meson and vector meson. Then, we consider the FSI method where the intermediate states are [Formula: see text] and [Formula: see text] via the exchange of [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] to improve the branching ratio. The above intermediate states are calculated by using the QCDF method. In the FSI effects, the results of our calculations depend on [Formula: see text] as the phenomenological parameter. The experimental branching ratio of this decay is [Formula: see text]. Our results in QCDF approach is [Formula: see text], and with [Formula: see text], the improved branching ratio is [Formula: see text].


2015 ◽  
Vol 30 (33) ◽  
pp. 1550196 ◽  
Author(s):  
Yogesh Kumar ◽  
Poonam Jain

We show the extended calculation of leading order process for photon production from Quark–Gluon Plasma (QGP) using a finite quark mass incorporating phenomenological parameter of quarks and gluons with the effect of quark chemical potential. The photon emission rate is observed in the range of low and intermediate transverse momentum. Our modified results of photon production give significant contribution in the range of quark phenomenological parameter, i.e. [Formula: see text] of high-energy heavy-ion collisions. The results obtained are compared with other results.


2001 ◽  
Vol 27 (8) ◽  
pp. 683-685 ◽  
Author(s):  
O. V. Konstantinov ◽  
E. Yu. Kotel’nikov ◽  
A. V. Matveentsev ◽  
A. E. Romanov

2000 ◽  
Vol 198 ◽  
pp. 113-115
Author(s):  
J.A. S. Lima ◽  
J. S. Alcaniz ◽  
J. Santos ◽  
R. Silva

In hot big bang cosmologies, the irreversible process of continous photon creation may phenomenologically be described through a thermodynamic approach. In these models, the radiation temperature law depends on a phenomenological parameter β which is closely related to the photon creation rate. It is shown that a stringent constraint on the value of this parameter is imposed from primordial nucleosynthesis.


1992 ◽  
Vol 07 (22) ◽  
pp. 5475-5498 ◽  
Author(s):  
R. BÖNISCH ◽  
R. KÖGERLER

The nonlinear version of the electroweak gauge theory (BESS model) is considered. It contains no physical Higgs particle but, instead, a further triplet of massive gauge bosons. Parameter bounds are derived which can be deduced from expected data of high precision experiments. The induced fermionic couplings which emerge due to the model’s nonrenormalizability are treated in a consistent way.


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