arXiv subjects

Renata Jora

Publications and source records attributed to Renata Jora.

At least 19 recordsLinked to original sources

arXiv2020

A theoretical analysis of the doubly radiative decays $η^{(\prime)}\toπ^0γγ$ and $η^\prime\toηγγ$

The scalar and vector meson exchange contributions to the doubly radiative decays $η^{(\prime)}\toπ^0γγ$ and $η^\prime\toηγγ$ are analysed within the Linear Sigma Model and Vector Meson Dominance frameworks, respectively. Predictions for the diphoton invariant mass spectra and the associated integrated branching ratios are given and compared with current available experimental data. Whilst a satisfactory description of the shape of the $η\toπ^{0}γγ$ and $η^\prime\toπ^{0}γγ$ decay spectra is obtained, thus supporting the validity of the approach, the corresponding branching ratios cannot be reproduced simultaneously. A first theoretical prediction for the recently measured $η^\prime\toηγγ$ by the BESIII collaboration is also presented.

hep-ph↗

arXiv2020

Electromagnetic potentials and radiation of the Proca field created by a massless charge

We study a theory less explored in the literature, that of a massive abelian gauge boson interacting with a massless fermion. In this framework we calculate the electromagnetic potentials created by a point like massless charge. We determine also the radiation associated with a change in the momentum of the charge in the low energy regime. The results show both similarities and discrepancies with respect to quantum electrodynamics.

hep-ph↗

arXiv2020

Note about the spin connection in general relativity

In general relativity the fermions are treated from the perspective of the gauged Lorentz group and by introducing the corresponding gauge fields the spin connection. This procedure is intimately related to the so-called "vielbein" formalism and stems from the general structure that can be associated to a manifold, the affine connection. In this work we derive the correct spin connection based only on the general covariance of the theory, on the gauged Lorentz symmetry and on the known space-time properties of fermion bilinears generalized to the curved space. Our result coincides exactly with the spin connection obtain through the tetrad formalism.

gr-qc↗

arXiv2020

Unimodular gauge fixing in general relativity revisited

We study a slight variation of the unimodular gauge condition which we call "the derivative gauge condition". We show that at the classical level these conditions are completely equivalent up to a surface term. At the quantum level the derivative gauge condition can be easily implemented by analogy with gauge fixing in a quantum gauge theory. This condition might have advantages and disadvantages upon the context.

gr-qc↗

arXiv2020

Anomaly of a gauge theory under rescaling of the fields

We determine the anomaly associated to an arbitrary scaling of the fields in a quantum gauge theory without making use of the Fujikawa method. We show that this anomaly is dependent on the spin term present in the action and at one loop can be directly extracted from the spin contribution to the one loop effective action. Our results can be readily applied to any gauge theory, supersymmetric or not and agree with previous determination for supersymmetric gauge theories based on the Fujikawa method.

hep-th↗

arXiv2020

A solution for the cosmological constant problem

We consider that the cosmological constant is associated with the vacuum energy density of a particle physics model. In the path integral formalism of euclidean quantum gravity and in the background of the Robertson Walker metric we calculate only the contribution of the matter density to the fluctuating metric. This produces an effective term in the action that acts as a correction to the vacuum energy density of the matter. The method leads to the observed cosmological constant without the need of any fine tuning in the gravity or particle physics sectors.

physics.gen-ph↗

arXiv2019

Trace and axial anomalies on equal footing

We discuss for some particular non supersymmetric theories a generalized symmetry that includes both the scale and axial transformations and leads to a single current that may contain also a pseudoscalar term. The method, inspired by the superconformal anomalies has important application for low energy effective models where it allows the introduction of a single complex glueball field with a scalar and a pseudoscalar component on the same footing with the complex meson nonets fields made of quarks. Both axial and trace and axial anomalies are satisfied in accordance to the meson structure and the QCD requirements.

hep-ph↗

arXiv2019

Non-perturbative renormalization of the Yang-Mills beta functions

We determine the non-perturbative corrections to the gauge coupling constant and the topological charge in the Yang Mills theory. The method makes no explicit use of instanton calculations but instead relies on boundary properties of the quantum partition function. The approach may offer important clues regarding the behavior of the coupling constant and the theta angle for other gauge theories like QCD and supersymmetric QCD.

hep-ph↗

arXiv2019

The infrared or ultraviolet scale for a gauge theory

We propose a conjecture that leads to the determination of the intrinsic scale (the scale at which the coupling constant diverges) for any gauge theory by comparison to another theory for which there is phenomenological information, provided that the two theories are placed in the same space-time volume. This conjecture is verified independently for $U(1)_{em}$ and for $QCD$. In this framework and from this perspective we show that the group $SO(10)$ is the only viable candidate among the supersymmetric GUT groups $SU(5)$, $SO(10)$ and $E_6$.

hep-ph↗

arXiv2019

A solution for the doublet-triplet splitting in $SU(5)$

We present a solution to the doublet-triplet splitting problem in supersymmetric $SU(5)$ by enlarging the group to $SU(5)\times SU(5)$ and by introducing two supermultiplets in the $(5,5)$ and $(\bar{5},\bar{5})$ representations of the extended group. The non-perturbative superpotential associated to this gauge group provides not only the correct gauge symmetry breaking but also the large mass for the Higgs triplets associated to massless Higgs doublet. The method has all the advantages of the sliding singlet model but without the drawbacks.

hep-ph↗

arXiv2019

Quark and gluon condensates in QCD reevaluated

We compute the quark and gluon condensates in $QCD$ with $N$ colors and $N_f$ flavors based on the renormalization group equations and on the knowledge of a single scale $Λ_{QCD}$. For $N=3$ and $N_f=3$ our findings are in the good range for $0.2\leqΛ_{QCD}\leq 0.36$ and in excellent agreement with the results in the literature from sum rules for a value $Λ_{QCD}=0.28$.

hep-ph↗

arXiv2019

Note on the Witten index and the dynamical breaking of a supersymmetric gauge theory

It is known that in order for a supersymmetric gauge theory to be dynamically broken a necessary but not sufficient condition is that the Witten index $(-1)^F=n_b^0-n_f^0$ is zero. In the case the Witten index is zero it is in general hard to distinguish between theories with or without dynamical supersymmetry breaking. In this work we show that for a large class of theories the cancellation of the Witten index by itself signals the formation of a quark condensate and therefore produces dynamical supersymmetry breaking.

hep-ph↗

arXiv2019

Witten index and dynamical supersymmetry breaking of a gauge theory

We estimate the Witten index for a supersymmetric gauge theory with or without massless matter. For pure supersymmetric Yang Mills our result reproduces the results in the literature. For the known theories with dynamical symmetry breaking the Witten index is determined to be exactly zero. Our calculation sheds light on the possibility of dynamical supersymmetry breaking for those theories considered up to now unsolvable.

hep-ph↗

arXiv2019

Supersymmetric QCD with $N_f<N$ revisited

We introduce in supersymmetric QCD with $N_f<N$ additional meson singlet degrees of freedom made of $2N_f-2$ supermultiplets. We construct an alternative superpotential with $N_f^2$ constraints and show its consistency. Based on this superpotential we prove that for $\frac{N}{2}<N_f<N$ the supersymmetry is unbroken whereas for $N_f\leq\frac{N}{2}$ is dynamically broken.

hep-ph↗

arXiv2018

About electrodynamics, standard model and the quantization of the electrical charge

The quantization of the electrical charge in the electrodynamics and of the hypercharge in the standard model are imposed in the theory based not on theoretical arguments but on the experimental observations. In this paper we propose a quantum consistency condition in a theory where Ward identities are respected that requires the quantization of the charge within the framework of the theory without external impositions. This refers to the renormalization conditions in the background gauge field method such that to ensure a correct mathematical correspondence between the bare partition function and the renormalized one. Applied to the standard model of elementary particles our criterion together with the anomaly cancellation condition leads to the correct hypercharge assignment of all standard model fermions.

hep-ph↗

arXiv2018

Note on the gluino condensate in supersymmetric Yang Mills theory

We calculate gluino condensate for supersymmetric Yang Mills theory on general grounds without making any assumption with regard to the weak or strong regime of the theory. Our result coincides with that obtained from an instanton superpotential when the theory is weakly interacting. The method also determines the corresponding partition function.

hep-ph↗

arXiv2018

Comment on some particular phases of supersymmetric QCD

We study two phases of supersymmetric QCD associated to the singularities of the renormalization constant of the fermion mass operator. We find a behavior of the potential between two charges for the phases of interest that it is consistent with Seiberg results on these aspects based on a different method.

hep-ph↗

arXiv2018

Generalized linear sigma model with two glueballs

We present a generalized linear sigma model that includes both scalar and pseudoscalar glueballs in addition to a quark-antiquark as well as a four-quark chiral nonet. Utilizing the axial and trace anomalies of QCD (at the effective mesonic level), we aim to develope the most general structure of the Lagrangian which can be used to study the interaction of quarkonia with glueballs. We then study the effect of scalar glueball on the vacuum of the model by considering a decoupling limit in which the glueball fields are decoupled from quarkonia. This determines the properties of the pure scalar glueball and builds a practical foundation for determining the model parameters when the interactions are turned on.

hep-ph↗