arXiv subjects

O. V. Zenin

Publications and source records attributed to O. V. Zenin.

13 recordsLinked to original sources

arXiv2026

Dispersive estimation of the LO hadronic contribution to the muon ${g-2}$: fitting incompatible ${e^+e^-}$ data

Using an up-to-date compilation of $σ_{\mathrm{tot}}(e^+e^- \to hadrons)$ data we estimated the LO hadronic contribution to the muon anomalous magnetic moment, $a_μ(had,LO)$. Incompatibilities between $σ_{\mathrm{tot}}(e^+e^- \to hadrons)$ measurements by independent experiments are mitigated by extra systematic uncertainties estimated using as a guideline a requirement of uniformity of $χ^2$ distribution over degrees of freedom in joint fits of $σ_{\mathrm{tot}}$. Tensions in the $e^+e^-$ input data translate into an expanded uncertainty of the $a_μ(had,LO) = (697.7 \pm {9.8}_{e^+e^-} \pm 3.6_{sys}) \times 10^{-10}$. Given this, we obtain the SM prediction for the muon anomaly $a_μ^{\mathrm{SM}} = 11659185.5(10.6) \times 10^{-10}$, below the experimental world average $a_μ^{\mathrm{exp}}$ at $2σ$ level.

hep-ph↗

arXiv2025

Multiscalar-metric gravity: merging gravity, dark energy and dark matter

The status of a modification of General Relativity (GR) -- Spontaneously Broken Relativity (SBR) -- for merging gravity, dark energy (DE) and dark matter (DM) is presented. The modification is principally grounded on a multiscalar-metric concept of spacetime endowed with two dynamical structures: a basic metric and a set of the reversible multiscalar fields. The latter ones serve geometrically as exceptional dynamical coordinates among arbitrary kinematical/observer's ones and physically as a kind of gravitational Higgs fields producing possible spontaneous breaking of the symmetry (SSB) of relativity. The effective field theory (EFT) of the extended gravity based on the multiscalar-metric spacetime -- the metagravity -- is discussed and some of its particular realizations beyond GR as SBR are explicated. Physically, SBR results in appearance of massive tensor and scalar gravitons. Some of the emerging consequences, problems and prospects for SBR for future deeper unification of gravity with matter in the context of the relativity and internal symmetries breaking are shortly discussed.

gr-qc↗

arXiv2025

Quartet-metric gravity and scalar graviton dark holes: supplements

This note includes results of a study of stationary spherically symmetric ``dark holes'', objects merging central black holes and peripheral scalar graviton dark haloes arising in the framework of the modified gravity -- the quartet-metric, or more appropriately, multiscalar-metric gravity with spontaneously broken relativity as a gauge symmetry [1]. An exact solution to be considered as a basic one for the dark holes is presented. This solution may, in principle, be used for a qualitative description of the effect of asymptotically flat rotation curves in galaxies. To convert the basic solution into a more realistic one suitable for astrophysical applications, a family of modified solutions is considered. These solutions are studied numerically for representative set of free parameters. These results were reported in the talk [2] but not included into the proceedings [3] due to article length limitations. The note can be considered as a supplement to this reference.

gr-qc↗

arXiv2025

Two-loop renormalization group restrictions on the standard model and the fourth chiral family

In the framework of the two-loop renormalization group, the global profile of the Standard Model (SM) in its full parameter space is investigated up to the scale of the gauge singularity. The critical Higgs masses bordering the strong coupling, unstable and the safe regions are explicitly found. Restrictions on the Higgs boson mass as a function of a cutoff scale are obtained from the stability of the electroweak vacuum and from the absence of the strong coupling both in the Higgs and Yukawa sectors. The cutoff being equal to the Plank scale requires the Higgs mass to be M=(161.3+-20.6)+4-10 GeV and M>=140.7+-10 GeV, where the M corridor is the theoretical one and the errors are due to the top mass uncertainty. The SM two-loop beta-functions are generalized to the massive neutrino case. Modification of the two-loop global profile of the SM extended by one new chiral family is studied, and bounds on the masses of the family are found. The requirement of self-consistency of the perturbative SM as an underlying theory up to the Planck or GUT scale excludes the fourth chiral family with the mass up to 250 GeV depending on the Higgs mass and the cutoff scale. Under precision experiment restriction M<=200 GeV, the fourth chiral family, taken alone, is excluded. Nevertheless a pair of the chiral families constituting the vector-like one could still exist.

hep-ph↗

arXiv2024

A comment on the impact of CMD-3 $e^+e^- \to π^+π^-$ cross section measurement on the SM $g_μ-2$ value

We estimated an impact of the recent CMD-3 measurement of the $e^+e^- \to π^+π^-$ total cross section at $0.3 < \sqrt{s} < 1.2$ GeV on the leading order hadronic contribution $a_μ^{had,LO}$ to the muon anomalous magnetic moment $a_μ= (g_μ-2)/2$, in presence of comparably precise ISR measurements of the cross section by BaBar and KLOE experiments being in significant tension with the CMD-3. Assuming that all the experiments are affected by yet unidentified systematic effects, to account for the latter, we scaled the experimental uncertainties following the PDG prescription, thus facilitating a consistent joint fit of the world data on the $e^+e^- \to π^+π^-$ total cross section. The same procedure was applied in all $e^+e^- \to hadrons$ channels contributing to the dispersive estimate of $a_μ^{had,LO}$. Despite an inclusion of the new CMD-3 $π^+π^-$ data, our estimate $a_μ^{had,LO}(e^+e^-) = (696.2 \pm 2.9) \times 10^{-10}$ is consistent with $a_μ^{had,LO}(e^+e^-)$ values obtained by other authors before publication of the CMD-3 result. Including our $a_μ^{had,LO}$ value into the SM prediction for $a_μ$, we obtain $a_μ^{SM} = (11~659~184 \pm 4_{\mathrm{tot}}) \times 10^{-10}$ which is by $4.7σ$ smaller than the world average for the experimental value $a_μ^{exp} = (11~659~205.9 \pm 2.2) \times 10^{-10}$. We confirm the observation by the CMD-3 authors that their $σ(e^+e^- \to π^+π^-)$ measurement, when taken alone, implies the $a_μ^{SM}$ prediction consistent with the $a_μ^{exp}$ at $\sim 1σ$ level.

hep-ph↗

arXiv2004

Hadronic Part of the Muon g-2 Estimated on the sigma_tot^2003(e+ e- --> hadrons) Evaluated Data Compilation

A comprehensive as of November 2003 and evaluated data compilation on sigma_tot(e+ e- --> hadrons) was used to estimate the lowest order hadronic contribution to the muon anomalous magnetic moment. The preliminary result is a_mu(had, LO) = (699.6 +- 1.9(rad) +- 2.0(proc) +- 8.5(e+e-)) * 10^-10 The Standard Model value of the muon magnetic anomaly calculated by updated SM formulae published or e-printed by November 2003 then reads a_mu = (1 165 918 3.5 +- 8.7(had) +- 4.0(LbL) +- 0.3(QED) +- 0.2(EW)) * 10^-10. This result deviates from the current experimental world average of a_mu by (-19.5 +- 9.6(theor) +- 8.0(exp)) * 10^-10, i.e. at 1.5 sigma level.

hep-ph↗

arXiv2002

Overview of the COMPETE Program

Nowadays, scientific databases have become the bread-and-butter of particle physicists. These databases must be maintained and checked repeatedly to insure the accuracy of their content. The COMPETE collaboration aims at motivating data maintenance via the interfacing of theory and experiment at the database level. The database concept then needs to be supplemented by a "model-base". Such an object enables one not only to decide what the best description may be, but also to discern what potential problems exist in the data. The systematization of such a cross-fertilization between models and data results in the "object of knowledge" that is the point at which all existing information resources on a given problem could converge. There are many advantages to such a global approach. First of all, the maintenance of a data set is not a static task: it needs to be motivated by physics. The second advantage is that one can have a common testing ground for theories and models. Thirdly, an extensive theoretical database can be used to plan new experiments and to predict various quantities. Finally, as new data come in, one can very quickly decide on their theoretical impact, and hence immediately evaluate the need for new physics ideas. As we want to treat a large amount of data and many models, computer technology constitutes an important part of our activity. We have concentrated on the elaboration of artificial intelligence decision-making algorithms, as well as on the delivery of computer tools for the end-user. Further linkage with existing databases, such as PDG, COMPAS, and HEPDATA is being developed or planned.

hep-ph↗

arXiv2002

Uncertainty of the two-loop RG upper bound on the Higgs mass

A modified criterion of the SM perturbative consistency is proposed. It is based on the analytic properties of the two-loop SM running couplings. Under the criterion adopted, the Higgs mass up to 380 GeV might not give rise to the strong coupling prior to the Planck scale. This means that the light Higgs boson is possibly preferred for reasons other than the SM peturbative consistency, i.e. for reasons beyond the SM.

hep-ph↗

arXiv2002

Total Cross Sections of e+ e- --> hadrons and pQCD Tests

In the light of recent muon (g-2) result by the E821 experiment at BNL, the importance of and interest in the total hadronic cross sections in e+ e- collisions and R(e+ e- --> hadrons) have been heightened. We report on the integrated data compilation of available data of e+ e- --> hadrons, transformed to a unique and meaningful style that implements the pure QED radiative corrections, from the PPDS and HEPDATA databases by the COMPETE Group. In particular, the continuum data sets are extracted where the direct comparison of the parton models and different variants of the pQCD corrections can be made and which will be useful for the future refinements of alpha_s(Q^2) and alpha_QED(Q^2).

hep-ph↗

arXiv2001

A compilation of total cross section data on e^+ e^- --> hadrons and pQCD tests

All available data on the total cross sections and R-ratio of e^+ e^- --> hadrons are compiled from the PPDS(DataGuide), PPDS(ReacData) and HEPDATA(Reaction) databases and transformed to a compilation of data on the e^+ e^- --> quark antiquark --> hadrons in the continuum region which can be used in tests of the parton model and pQCD calculations. This evaluated data compilation is made available in PPDS system and is accessible through the Web. It is shown that current predictions from the parton model and pQCD are well supported by this world "continuum" data compilation which can then be used in future refinements of the alpha_s(Q^2) as well as alpha_{QED}(Q^2) evolution forms.

hep-ph↗

arXiv1999

Quark masses and mixings in the standard model with heavy vector-like families

The extension of the standard model with pairs of the vector-like families is studied. The quark mixing matrices for the left- and right-handed charged currents, as well as those for the flavour changing neutral currents, the Z and Higgs mediated, are found. Both the model independent parametrization for an arbitrary case and an explicit realization for the case with one pair of the heavy vector-like families are presented. The extension opens new prospects for studying deviations from the standard model in the future experiments at high energies.

hep-ph↗

arXiv1999

Vector-like family extension of the standard model and the light quark masses and mixings

The standard model extended with the pairs of the vector-like families is studied. The model independent analysis for an arbitrary case and an explicit realization for the case with one pair of the heavy vector-like families are considered. The mixing matrices of the light quarks for the left- and right-handed charged currents, as well as those for the flavour changing neutral currents, both the Z and Higgs mediated, are found.

hep-ph↗

arXiv1998

Two-loop renormalization group profile of the standard model and a new generation

The two-loop renormalization group global profile of the Standard Model (SM) in its full parameter space is investigated. Restrictions on the Higgs boson mass as a function of a cutoff scale are obtained from the stability of the electroweak vacuum and from the perturbative validity both in the Higgs and Yukawa sectors. The cutoff equal to the Planck scale requires the Higgs mass to be M=(161.3+-20.6)+4-10 GeV and M>=140.7+-10 GeV, where the M corridor is the theoretical one and the errors are due to the top mass uncertainty. Modification of the two-loop global profile of the SM extended by one new chiral generation is studied, and bounds on the masses of the generation are derived. Under the precision experiment restriction M<=200 GeV, the forth chiral generation, taken alone, is excluded. Nevertheless a pair of the chiral generations constituing the vector-like one could exist.

hep-ph↗