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T. Gutsche

Publications and source records attributed to T. Gutsche.

12 recordsLinked to original sources
arXiv2016

Effect of the $ηη$ channel and interference phenomena in the two-pion transitions of charmonia and bottomonia

The basic shape of di-pion mass spectra in the two-pion transitions of both charmonia and bottomonia states is explained by an unified mechanism based on contributions of the $ππ$, $K\overline{K}$ and $ηη$ coupled channels including their interference. The role of the individual $f_0$ resonances in shaping the di-pion mass distributions in the charmonia and bottomonia decays is considered.

hep-ph↗
arXiv2015

Effect of coupled channels of the multi-channel pion-pion scattering in two-pion transitions of the $Υ$ mesons

The effect of isoscalar S-wave processes $ππ\toππ,K\overline{K},ηη$ is considered in the analysis of data (from the ARGUS, CLEO, CUSB, Crystal Ball, Belle, BABAR collaborations) on the bottomonia decays --- $Υ(mS)\toΥ(nS)ππ$ ($m>n, m=2,3,4,5, n=1,2,3$). It is shown that the dipion mass spectra of these decays are explained by the unified mechanism related to the contribution of the multichannel $ππ$ scattering in the final states of these reactions. Since in the analysis the multichannel $ππ$-scattering amplitudes did not change in comparison with the ones in our combined analysis of data on the multichannel $ππ$ scattering and on the charmonia decays --- $J/ψ\toϕ(ππ, K\overline{K})$ and $ψ(2S)\to J/ψ(ππ)$ (from the Crystal Ball, DM2, Mark II, Mark III, and BES II) --- the results confirm all our earlier conclusions on the scalar mesons.

hep-ph↗
arXiv2014

The effect of multi-channel pion-pion scattering in decays of the $Υ$-family mesons

The effect of isoscalar S-wave multi-channel pion-pion scattering ($ππ\toππ,K\bar{K},ηη$) is considered in the analysis of data on decays of the $Υ$-meson family -- $Υ(2S)\toΥ(1S)ππ$, $Υ(3S)\toΥ(1S)ππ$ and $Υ(3S)\toΥ(2S)ππ$. The analysis, which aims at studying the scalar mesons, is performed jointly considering the multi-channel pion-pion scattering, which is described in our model-independent approach based on analyticity and unitarity and using an uniformizing variable method, and the charmonium decay processes $J/ψ\toϕ(ππ, K\bar{K})$, $ψ(2S)\to J/ψ(ππ)$. Results of the analysis confirm all our earlier conclusions on the scalar mesons. It is also shown that in the final states of the $Υ$-meson family decays (except for the $ππ$ scattering) the contribution of the coupled processes, e.g., $K\bar{K}\toππ$, is important even if these processes are energetically forbidden. This is in accordance with our previous conclusions on the wide resonances: If a wide resonance cannot decay into a channel which opens above its mass but the resonance is strongly connected with this channel (e.g. the $f_0(500)$ and the $K\bar}$ channel), one should consider this resonance as a multi-channel state with allowing for the indicated channel taking into account the Riemann-surface sheets related to the threshold branch-point of this channel and performing the combined analysis of the considered and coupled channels.

hep-ph↗
arXiv2005

Neutrinoless double beta decay and neutrino mass hierarchies

In the framework of the see-saw mechanism the normal hierarchy is favorable for the neutrino mass spectrum. For this spectrum we present a detailed calculation of the half-lives of neutrinoless double beta decay for several nuclei of experimental interest. The half-lives are evaluated by considering the most comprehensive nuclear matrix elements, which were obtained within the renormalized QRPA by the Bratislava-Caltech-Tuebingen group. The dependence of the half-lives on sin^2 theta_{13}$ and the lightest neutrino mass is studied. We present also the results of the calculations of the half-lives of neutrinoless double beta decay in the case of the inverted hierarchy of neutrino masses.

hep-ph↗
arXiv2002

Neutron-Proton High-Energy Charge Exchange Scattering

The high energy proton-neutron charge exchange scattering reaction is studied in an effective hadron model for the energy range of s from 45.9 to 414.61 GeV*GeV. The main features of the observed differential cross section, the forward peak and the scaling behavior over a large energy region, are well reproduced.

hep-ph↗
arXiv2000

Thermal QCD sum rules in the $ρ^0$ channel revisited

From the hypothesis that at zero temperature the square root of the spectral continuum threshold $s_0$ is linearly related to the QCD scale $Λ$ we derive in the chiral limit and for temperatures considerably smaller than $Λ$ scaling relations for the vacuum parts of the Gibbs averaged scalar operators contributing to the thermal operator product expansion of the $ρ^0$ current-current correlator. The scaling with $λ\equiv \sqrt{s_0(T)/s_0(0)}$, $s_0$ being the $T$-dependent perturbative QCD continuum threshold in the spectral integral, is simple for renormalization group invariant operators, and becomes nontrivial for a set of operators which mix and scale anomalously under a change of the renormalization point. In contrast to previous works on thermal QCD sum rules with this approach the gluon condensate exhibits a sizable $T$-dependence. The $ρ$ -meson mass is found to rise slowly with temperature which coincides with the result found by means of a PCAC and current algebra analysis of the $ρ^0$ correlator.

hep-ph↗
arXiv2000

Vacuum structure of a modified MIT Bag

An alternative to introducing and subsequently renormalizing classical parameters in the expression for the vacuum energy of the MIT bag for quarks is proposed in the massless case by appealing to the QCD trace anomaly and scale separation due to asymptotic freedom. The explicit inclusion of gluons implies an unrealistically low separation scale.

hep-ph↗
arXiv1999

Glueball-quarkonia content and decay of scalar-isoscalar mesons

We investigate the hadronic two-body decay modes of the scalar-isoscalar $f_0(1370)$, $f_0(1500)$ and $f_0(1710)$ states as resulting from the mixture of the lowest lying scalar glueball with the isoscalar states of the ground state $^3P_0$ $Q\bar Q$ nonet. In the decay analysis we take into account the direct coupling of the quarkonia and glueball components of the $f_0$ states to the quarkonia components of the two-meson final state with the decay dynamics inspired by the strong coupling limit of QCD. We calculate partial decay widths for the $f_0$ states in the proposed three-state mixing schemes and discuss their compatibility with the observed decay features. Finally, we determine the glueball-quarkonia content of the $f_0$ states from a detailed fit to experimental decay data of $f_0(1500)$ and give predictions for the partial decay widths of $f_0(1370)$ and $f_0(1710)$, providing thus a sensitive test of the proposed mixing scheme.

hep-ph↗
arXiv1999

Radiative proton-antiproton annihilation and isospin mixing in protonium

A detailed analysis of the radiative $p\bar p$ annihilation is made in the framework of a two-step formalism, the $p\bar p$ annihilates into meson channels containing a vector meson with a subsequent conversion into a photon via the vector dominance model (VDM). Both steps are derived from the underlying quark model. First, branching ratios for radiative protonium annihilation are calculated and compared with data. Then, details of the isospin interference are studied for different models of the initial protonium state and also for different kinematical form factors. The isospin interference is shown to be uniquely connected to the $p\bar p - n\bar n $ mixing in the protonium state. Values of the interference terms directly deduced from data are consistent with theoretical expectations, indicating a dominant $p\bar p$ component for the $^1S_0$ and a sizable $n\bar n$ component for the $^3S_1$ protonium state. The analysis is extended to the $p\bar p \to γΦ$ transition, where the large observed branching ratio remains unexplained in the VDM approach.

nucl-th↗
arXiv1998

$4π$ Decay Modes of the $f_0(1500)$ Resonance

We investigate the two-body decay modes $ρρ, ππ^{\ast}(1300)$ and $σσ$ of the $f_0(1500)$, all leading to the $4π$ decay channel, in a three-state mixing scheme, where the $f_0(1500)$ is a mixture of the lowest-lying scalar glueball with the nearby isoscalar states of the $0^{++} Q\bar{Q}$ nonet. In the leading order of this scheme, the decay mechanism of the $f_0(1500)$ proceeds dominantly via its quarkonia components, which can be described in the framework of the $^3P_0$ $Q\bar Q$ pair creation model. We predict the hierarchy of decay branching ratios B with $B(ρρ) ^{>}_{\sim} B(ππ) ^{>}_{\sim} B(σσ) > B(ππ^{\ast})$, providing a key signature for the proposed mixing scheme in this leading order approach.

hep-ph↗