Search arXiv⌕ Search

arXiv · hep-ph/9607341

Multiple Point Criticality, Nonlocality, and Finetuning in fundamental physics: predictions for Gauge Coupling Constants gives $α^{-1}=136._8\pm 9

Abstract

The Multiple Point Criticality Principle (MPCP) states that action parameters - in for example a field theory - take on values corresponding to the junction of a maximum number of phases in the phase diagram of a system that undergoes phase transitions. The phases to which physical significance is ascribed are normally regarded as artifacts of a regulation procedure. In the context of a Y-M lattice gauge theory, the MPCP is applied to the system of different (Planck scale) lattice phases that can be provoked using a suitably generalised action with a gauge group that is taken to be the Planck scale predecessor to the Standard Model Group (SMG) - namely the $N_{gen}$-fold Cartesian product of the SMG. Here $N_{gen}$ is the number of fermion generations. Ambiguities under mappings of the gauge group $SGM^{N_{gen}}$ onto itself result in the Planck scale breakdown to the diagonal subgroup which is isomorphic to the usual SMG. Assuming the validity of the MPCP, the three SMG gauge couplings at the Planck scale are predicted to be equal to the diagonal subgroup couplings correspond- ing to the multiple point action parameters in a lattice gauge theory with the gauge group $SMG^{N_{gen}}$. This prediction gives agreement with experiment to within 10 \% for the non-Abelian couplings and 5\% for the U(1) gauge coup- ling. In a more general context, the MPCP is proposed as a fundamental princi- ple of Nature that can also explain other fine-tuning enigma in high energy physics. It is argued that the MPCP implies having long range nonlocal inter- actions which are identical between fields at all pairs of spacetime points. Such interactions are allowed in a very general form of a reparameterization invariant action. This phenomenologically unobjectionable form of nonlocality would quite naturally be incorporated into our theory as constants of Nature.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Donald L. Bennett. 1996-07-16. Multiple Point Criticality, Nonlocality, and Finetuning in fundamental physics: predictions for Gauge Coupling Constants gives $α^{-1}=136._8\pm 9. https://arxiv.org/abs/hep-ph/9607341

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

Extraction of the pion-nucleon coupling constant using the effective-range expansion with the left-hand cut

We apply the generalized effective-range expansion of Phys. Rev. Lett. 135, 011903(2025), which incorporates the left-hand cut from one-pion exchange, to low-energy neutron-proton scattering in the $^1S_0$ and $^3S_1$ channels. The amplitude zero for the center-of-mass momentum near 0.35 GeV in the $^1S_0$ channel is naturally accommodated within this framework. We extract the pole position, scattering length, effective range, and the pseudoscalar pion-nucleon coupling constant $g_{πN}^2/(4π)$ at different expansion orders. The low-energy parameters are stable and consistent with established values, while $g_{πN}^2/(4π)$ exhibits larger uncertainties. The extraction of $g_{πN}^2/(4π)$ is data-driven, relying on the analytic constraints from the left-hand cut and phase-shift data within the one-pion-exchange approximation. Despite larger uncertainties compared to high-precision extractions, the consistency with established values demonstrates that this framework can probe the left-hand-cut singularity.

hep-ph↗

True Leptonium ($l^+ l^-$) Production in UPC Triphoton Interaction

True leptonium states ($l^+ l^-$) are compact pure QED systems, first theoretically predicted eight decades ago. Although considerable efforts have been devoted to their search, only positronium has been experimentally confirmed shortly after its theoretical prediction. By contrast, dimuonium ($μ^+ μ^-$) and tauonium ($τ^+ τ^-$) remain unobserved to date, partly due to their low production yields. In this work, we investigate ortho-leptonium production through triphoton interactions in ultraperipheral heavy-ion collisions (UPCs). Two photons originate from different ions in one beam, while the third is supplied by an ion in the opposing beam. Within the equivalent photon approximation, we compare continuum dimuon and $J/ψ$ production with UPC measurements and evaluate ortho-leptonium production at the LHC and FCC. The results illustrate the possible role of triphoton fusion in leptonium production and the sensitivity of the calculated rates to the low-energy photon input.

hep-ph↗

Semi-analytical two-loop QCD corrections to $e^+e^-\to J/ψ+χ_{cJ}$ at B factories

In this work, we compute the next-to-next-to-leading-order (NNLO) QCD corrections to the process $e^+e^-\to J/ψ+χ_{cJ}$ at B factories within the NRQCD factorization framework. The helicity amplitudes are obtained via asymptotic expansions around $r=0$ and $r=1$, with $r=16m_c^2/s$. Our asymptotic expressions reproduce the exact numerical results with high accuracy across the kinematic range $0\le r \le 1$, achieving a relative error below $10^{-5}$, which is sufficient for phenomenological applications. Notably, the large logarithmic terms are obtained analytically, and the explicit expressions established in this work provide a useful basis for further theoretical investigations. We compute the unpolarized cross sections. The $\mathcal{O}(α_s)$ correction is found to be large, while the $\mathcal{O}(α_s^2)$ correction for $χ_{c0}$ production amounts to $33\%$ of the leading-order (LO) cross section, significantly reducing the scale uncertainties. For $χ_{c1}$, the $\mathcal{O}(α_s)$ and $\mathcal{O}(α_s^2)$ corrections correspond to $35\%$ and $-15\%$, respectively. For $χ_{c2}$, the corresponding corrections are $24\%$ and $-38\%$. The large cancellation between the corrections for $χ_{c2}$ brings the NNLO cross section close to the LO prediction. Our prediction for $χ_{c0}$ is consistent with both the {\tt Belle} and {\tt BaBar} data within uncertainties. We also predict the angular distribution parameters $α^J_θ$, which are independent of nonperturbative inputs. A sharp discrepancy between the theory and the {\tt Belle} measurement is observed for $α^0_θ$, calling for further experimental and theoretical investigations. Moreover, future measurements of the angular distribution parameters for $χ_{c1}$ and $χ_{c2}$ will provide important tests of the theoretical framework.

hep-ph↗