arXiv subjects

Stanley F. Radford

Publications and source records attributed to Stanley F. Radford.

10 recordsLinked to original sources

arXiv2019

Vacuum polarization corrections to the $n=2$ and $n=3$ levels in muonic $^4$He

The $n=2$ and $n=3$ levels for muonic Helium are calculated using a potential that includes all one-loop and recoil effects. Electronic vacuum polarization corrections are calculated using an extension of Kinoshita and Nio method. For $n=2$, the results are $2p_{1/2}-2s_{1/2}=1375.05\pm 1.4$ meV and $2p_{3/2}-2s_{1/2}=1521.65\pm 1.4$ meV, essentially in agreement with the latest summary of the current calculations. The $n=3$ results are summarized in tabular form and give $3p_{1/2}-3s_{1/2}=394.76\pm 0.43$ meV and $3d_{3/2}-3p_{3/2}=111.40$ meV.

hep-ph↗

arXiv2016

Note on predictions for $c\bar{s}$ quarkonia using a three-loop static potential

We extend our treatment of the the spectroscopy and decays of the charm-strange quarkonium system to include the effect of using the full three-loop QCD correction to the static short distance potential. As before, our potential model consists of the relativistic kinetic energy term, a scalar linear confining term including its relativistic corrections and the perturbative QCD spin-dependent terms. A set of unperturbed wave functions for the various states is obtained using a variational technique that is further constrained by requiring that the wave functions also satisfy the relativistic virial theorem. These are then used in a perturbative treatment of the potential to fit the mass spectrum of the $c\bar{s}$ system and calculate the radiative decay widths. Our results accurately describe the $D_s$ spectrum and are compatible with the little data that is available for the radiative decays of the $D_s$ states.

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arXiv2013

Three-loop Static QCD Potential in Heavy Quarkonia

We investigate the effects of including the full three-loop QCD correction to the static short distance $1/r$ potential on the spectroscopy and decays in the charmonium and upsilon systems. We use a variational technique with the full three-loop corrected potential to determine a set of unperturbed trial wave functions and treat the relativistic and one-loop corrections as perturbations. The perturbed results are compared to the subset of the charmonium and upsilon spectra using a $χ^2$ test. This approach results in more accurate descriptions of the hyperfine splittings in both the $b\bar{b}$ and $c\bar{c}$ systems.

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arXiv2012

Potential model results for the newly discovered chi_b(3P) states

The ATLAS Collaboration has recently announced the discovery of the 3P states of the Upsilon system, chi_b(3P), with mass of 10.539+-0.004(stat.)+-0.008(syst.) GeV. In a previous investigation of the Upsilon system, in the context of a comprehensive one-loop potential model, we calculated the masses of these states, but did not include them. We present those results, and others for the n = 3 states here.

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arXiv2011

\ga\ga and g g decay rates for equal mass heavy quarkonia

We present a calculation of the two-photon and two-gluon widths for the equal mass quarkonium states $^1S_0$, $^3P_0$ and $^3P_2$ of the charmonium and upsilon systems. The approach taken is based on using the full relativistic $q\bar{q}\to\ga\ga$ amplitude together with a wave function derived from the instantaneous Bethe-Salpeter equation. Momentum space radial wave functions obtained from an earlier fit of the charmonium and upsilon spectra are used to evaluate the necessary integrals.

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arXiv2011

Hyperfine splittings in the $b\bar{b}$ system

Recent measurements of the $η_b(1S)$, the ground state of the $b\bar{b}$ system, show the splitting between it and the $\Up(1S)$ to be 69.5$\pm$3.2 MeV, considerably larger than lattice QCD and potential model predictions, including recent calculations published by us. The models are unable to incorporate such a large hyperfine splitting within the context of a consistent description of the energy spectrum and decays. We demonstrate that in our model, which incorporates a relativistic kinetic energy term, a linear confining term including its scalar-exchange relativistic corrections, and the complete one-loop QCD short distance potential, such a consistent description, including the measured hyperfine splitting, can be obtained by not softening the delta function terms in the hyperfine potential. We calculate the hyperfine splitting to be 67.5 MeV.

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arXiv2009

Potential model calculations and predictions for $\bm c\bar{\bm s}$ quarkonia

We investigate the spectroscopy and decays of the charm-strange quarkonium system in a potential model consisting of a relativistic kinetic energy term, a linear confining term including its scalar and vector relativistic corrections and the complete perturbative one-loop quantum chromodynamic short distance potential. The masses and wave functions of the various states are obtained using a variational technique, which are then used in a perturbative treatment of the potential to find the mass spectrum of the $c\bar{s}$ system and radiative decay widths. Our results compare well with the available data for the spectrum of $D_s$ states. We include a discussion of the effect of mixing and an investigation of the Lorentz nature of the confining potential.

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arXiv2008

Note on recent measurements of the $ψ(1S)\to\ga η_C(1S)$ and $ψ(2S)\to\ga η_C(1S)$ branching ratios

Recently published measurements of the branching ratios ${\cal B}(ψ(1S)\to\ga η_C(1S))$ and ${\cal B}(ψ(2S)\to\ga η_C(1S))$ by the CLEO collaboration are examined in the context of a potential model that includes both relativistic and one-loop QCD corrections to the quark-antiquark interaction. The prediction for the width $Γ(ψ(1S)\to\ga η_C(1S))$ is in excellent agreement with the new data but the prediction for $Γ(ψ(2S)\to\ga η_C(1S))$ is too small. In an effort to understand this discrepancy, we derive an upper bound on $Γ(ψ(2S)\to\ga η_C(1S))$ and point out its experimental value saturates this bound.

hep-ph↗

arXiv2007

Potential model calculations and predictions for heavy quarkonium

We investigate the spectroscopy and decays of the charmonium and upsilon systems in a potential model consisting of a relativistic kinetic energy term, a linear confining term including its scalar and vector relativistic corrections and the complete perturbative one-loop quantum chromodynamic short distance potential. The masses and wave functions of the various states are obtained using a variational technique, which allows us to compare the results for both perturbative and nonperturbative treatments of the potential. As well as comparing the mass spectra, radiative widths and leptonic widths with the available data, we include a discussion of the errors on the parameters contained in the potential, the effect of mixing on the leptonic widths, the Lorentz nature of the confining potential and the possible $c\bar{c}$ interpretation of recently discovered charmonium-like states.

hep-ph↗

arXiv2004

Describing Recently Discovered Narrow States as Quarkonia Using a Potential Model

We examine to what extent several recently discovered narrow resonances can be interpreted as conventional $c\bar{c}$ bound states describable using a potential model. In doing so, we use a semirelativistic approach, which includes both the $v^2/c^2$ and QCD one-loop corrections to the short distance potential and a long range linear potential together with its scalar and vector $v^2/c^2$ spin-dependent terms.

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