Quarkonium Spectroscopy Research Articles

Quantum computing for heavy quarkonium spectroscopy

We report a first demonstration for the application of quantum computing to heavy quarkonium spectroscopy study. Based on a Cornell-potential model for the heavy quark and antiquark system, we show how this Hamiltonian problem can be formulated and solved with the VQE approach on the IBM cloud quantum computing platform. Errors due to a global depolarizing noise channel are corrected with a zero-noise extrapolation method, resulting in good agreement with the expected value. We also extend the calculation to excited states on a noiseless quantum simulator by orthogonalization with respect to the ground state.

Space Dimension Renormdynamics

We aim to construct a potential better suited for studying quarkonium spectroscopy. We put the Cornell potential into a more geometrical setting by smoothly interpolating between the observed small and large distance behaviour of the quarkonium potential. We construct two physical models, where the number of spatial dimensions depends on scale: one for quarkonium with Cornell potential, another for unified field theories with one compactified dimension. We construct point charge potential for different dimensions of space. The same problem is studied using operator fractal calculus. We describe the quarkonium potential in terms of the point charge potential and identify the strong coupling fine structure constant dynamics. We formulate renormdynamics of the structure constant in terms of Hamiltonian dynamics and solve the corresponding motion equations by numerical and graphical methods, we find corresponding asymptotics. Potentials of a nonlinear extension of quantum mechanics are constructed. Such potentials are ingredients of space compactification problems. Mass parameter effects are motivated and estimated.

Erratum: Radiative improvement of the lattice nonrelativistic QCD action using the background field method with applications to quarkonium spectroscopy [Phys. Rev. D88, 014505 (2013)

Erratum: Radiative improvement of the lattice nonrelativistic QCD action using the background field method with applications to quarkonium spectroscopy [Phys. Rev. D<b>88</b>, 014505 (2013)

EXOTIC QUARKONIUM SPECTROSCOPY: X(3872), Zb(10610), AND Zb(10650) IN NON-RELATIVISTIC EFFECTIVE THEORY

This talk summarizes recent developments in quarkonium spectroscopy. I comment on the relation between the Zb(10610) and Zb(10650) and recently observed Zc(3900) and Zc(4025) states. Then I discuss a number of calculations using non-relativistic effective field theory for the X(3872), Zb(10610), and Zb(10650), under the assumption that these are shallow molecular bound states of charm or bottom mesons.

Studies of exotic quarkonium states at CMS

Using large data samples of dimuon events in pp collisions at TeV, CMS has performed studies in the field of "exotic" quarkonium spectroscopy. The production of the X(3872) is studied measuring the ratio of the X(3872) and ψ(2S) cross sections times their branching fractions into J/ψπ+π− as a function of transverse momentum (pT). In addition, the fraction of X(3872) originating from B decays is determined. From these measurements the prompt X(3872) differential cross section times branching fraction as a function of pT is extracted. The π+π− mass spectrum of the J/ψπ+π− system in the X(3872) decays is also investigated. Preliminary studies on structures in the J/ψϕ mass spectrum of the exclusive B+ → J/ψϕK+ decays are reported.

Radiative improvement of the lattice nonrelativistic QCD action using the background field method with applications to quarkonium spectroscopy

We apply the background field (BF) method to Non-Relativistic QCD (NRQCD) on the lattice in order to determine the one-loop radiative corrections to the coefficients of the NRQCD action in a manifestly gauge-covariant manner by matching the NRQCD prediction for particular on-shell processes with those of relativistic continuum QCD. We explain how the BF method is implemented in automated perturbation theory and discuss the technique for matching the relativistic and non-relativistic theories. We compute the one-loop radiative corrections to the sigma.B and Darwin terms for the NRQCD action currently used in simulations, as well as the one-loop coefficients of the spin-dependent O(alpha^2) four-fermion contact terms. The effect of the corrections on the hyperfine splitting of bottomonium is estimated using earlier simulation results; the corrected lattice prediction is found to be in agreement with experiment. Agreement of the hyperfine splitting of bottomonium and the B-meson system is confirmed by recent simulation studies (Dowdall et al.) which include our NRQCD radiative corrections for the first time.

Scalar Charged Particle in Presence of Magnetic and Aharonov–Bohm Fields Plus Scalar–Vector Killingbeck Potentials

The generalized form of Killingbeck potential is an attractive Coulomb term plus a linear term and a harmonic oscillator term, i.e. −a/r + br + λr2, which has a useful application in quarkonium spectroscopy. The ground state energy with the corresponding wave function are obtained for any arbitrary m-state in two-dimensional Klein–Gordon equation with equal mixture of scalar–vector Killingbeck potentials in the presence of constant magnetic and singular Ahoronov–Bohm flux fields perpendicular to the plane where the interacting charged particle is confined. The analytical exact iteration method is used in our solution. We obtain the energy eigensolutions for particle and antiparticle corresponding to S(r) = V(r) and S(r) = −V(r) cases, respectively. Some special cases like the Coulomb, harmonic oscillator potentials and the nonrelativistic limits are found in presence and absence of external fields.

Review of Particle Physics

This biennial Review summarizes much of particle physics. Using data from previous editions, plus 2658 new measurements from 644 papers, we list, evaluate, and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as Higgs bosons, heavy neutrinos, and supersymmetric particles. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as the Standard Model, particle detectors, probability, and statistics. Among the 112 reviews are many that are new or heavily revised including those on Heavy-Quark and Soft-Collinear Effective Theory, Neutrino Cross Section Measurements, Monte Carlo Event Generators, Lattice QCD, Heavy Quarkonium Spectroscopy, Top Quark, Dark Matter, Vcb & Vub, Quantum Chromodynamics, High-Energy Collider Parameters, Astrophysical Constants, Cosmological Parameters, and Dark Matter. A booklet is available containing the Summary Tables and abbreviated versions of some of the other sections of this full Review. All tables, listings, and reviews (and errata) are also available on the Particle Data Group website: http://pdg.lbl.gov/. The 2012 edition of Review of Particle Physics is published for the Particle Data Group as article 010001 in volume 86 of Physical Review D. This edition should be cited as: J. Beringer et al. (Particle Data Group), Phys. Rev. D 86, 010001 (2012).Received 18 July 2012DOI:https://doi.org/10.1103/PhysRevD.86.010001© 2012 Regents of the University of California*The publication of the Review of Particle Physics is supported by the Director, Office of Science, Office of High Energy and Nuclear Physics, the Division of High Energy Physics of the U.S. Department of Energy under Contract No. DE–AC02–05CH11231; by the U.S. National Science Foundation under Agreement No. PHY-0652989; by the European Laboratory for Particle Physics (CERN); by an implementing arrangement between the governments of Japan (MEXT: Ministry of Education, Culture, Sports, Science and Technology) and the United States (DOE) on cooperative research and development; and by the Italian National Institute of Nuclear Physics (INFN).

Quarkonium spectroscopy and search for new states at BaBar

The BaBar experiment at the PEP-II B-factory gives excellent opportunities for the quarkonium spectroscopy. Investigation of the properties of new states like the X (3872), Y (3940) and Y (4260) are performed aiming to understand their nature. Recent BaBar results will be presented in this paper.

New Spectroscopy at BaBar

The Babar experiment at the SLAC B factory has accumulated a high luminosity that offers the possibility of systematic studies of quarkonium spectroscopy and of investigating rare new phenomena. Recent results in this field are presented.

Production of the hc and hb and implications for quarkonium spectroscopy

The recent observation of the hc is an important test of QCD calculations and provides constraints on models of quarkonium spectroscopy. In this contribution I discuss some of these implications and describe methods to search for the hc and hb via radiative transitions and other means.

Understanding heavy quarkonium systems in perturbative QCD

We review the recent theoretical progress in heavy quarkonium spectroscopy within the boundstate theory based on perturbative QCD. New microscopic pictures of the heavy quarkonium systems are obtained.

Connection between the perturbative QCD potential and phenomenological potentials

When the cancellation of the leading renormalon contributions is incorporated, the total energy of a b bbar system, E_{tot,bbbar}(r) = 2 m_{pole,b} + V_QCD(r), agrees well with the potentials used in phenomenological models for heavy quarkonia in the range 0.5 GeV^-1 < r < 3 GeV^-1. We provide a connection between the conventional potential-model approaches to the quarkonium spectroscopy and the recent computation based on perturbative QCD.

Quarkonium spectroscopy and perturbative QCD: Massive quark-loop effects

We study the spectra of the bottomonium and ${B}_{c}$ states within perturbative QCD up to order ${\ensuremath{\alpha}}_{\mathrm{s}}^{4}.$ The $\mathcal{O}({\ensuremath{\Lambda}}_{\mathrm{QCD}})$ renormalon cancellation between the static potential and the pole mass is performed in the \ensuremath{\varepsilon}-expansion scheme. We extend our previous analysis by including the (dominant) effects of nonzero charm-quark mass in loops up to the next-to-leading nonvanishing order ${\ensuremath{\varepsilon}}^{3}.$ We fix the b-quark $\overline{\mathrm{MS}}$ mass ${m}_{b}\ensuremath{\equiv}{m}_{b}^{\overline{\mathrm{MS}}}{(m}_{b}^{\overline{\mathrm{MS}}})$ on $\ensuremath{\Upsilon}(1S)$ and compute the higher levels. The effect of the charm mass decreases ${m}_{b}$ by about 11 MeV and increases the $n=2$ and $n=3$ levels by about 70--100 MeV and 240--280 MeV, respectively. We provide an extensive quantitative analysis. The size of nonperturbative and higher order contributions is discussed by comparing the obtained predictions with the experimental data. An agreement of the perturbative predictions and the experimental data depends crucially on the precise value (inside the present error) of ${\ensuremath{\alpha}}_{\mathrm{s}}{(M}_{Z}).$ We obtain ${m}_{b}^{\overline{\mathrm{MS}}}{(m}_{b}^{\overline{\mathrm{MS}}})=4190\ifmmode\pm\else\textpm\fi{}20\ifmmode\pm\else\textpm\fi{}25\ifmmode\pm\else\textpm\fi{}3\mathrm{MeV}.$

Update on quarkonium spectroscopy and α strong from NRQCD

NRQCD results for Upsilon and Charmonium using both dynamical and quenched configurations are presented. We investigate dependence on the light dynamical quark mass. Preliminary dynamical (nƒ = 2) Charmonium data are combined with quenched results to extract the strong coupling constant αp(nf) for the physical number of light dynamical quarks, nƒ = 3. Good agreement is found with calculations based on the Upsilon system. We show that a discrepancy in αpnf=0, found between the Upsilon and Charmonium systems in the quenched theory, disappears upon extrapolating to the physical number of flavors. Results for the strong coupling constant α M S ¯ are presented and sources of systematic error investigated.

Spin dependence of the heavy-quark potential: a QCD lattice analysis

We have investigated the spin dependence of the potential between heavy quarks in full lattice QCD, including the effects of light quark loops. The form of the spin-orbit, the tensor and the spin-spin forces present clear evidence for long-range scalar confinement supplemented by a Coulomb force at short distances. This agrees with observations from quarkonium spectroscopy. The QCD simulation has been carried out for Kogut-Susskind fermions with four degrees of freedom at a gauge coupling β = 5.35 and a quark mass am q = 0.01 on a 16 3 × 24 size lattice. This corresponds to a lattice spacing 0.12 fm, a spatial lattice size of about 2 fm and a light quark mass of 48 MeV.

Exact string potential and heavy quarkonia.

Using the exact form of the static string potential we reinvestigate previous potential-model calculations of the energy levels of {ital q{bar q}} resonances. We show the effect of higher-order corrections to strings on the quarkonium spectroscopy and the leptonic decays of the {Upsilon} and {ital J}/{psi}, where we find that the roughened form of the string potential has a significant effect. We also propose a new form of the potential which incorporates both the quantum effects and asymptotic freedom.

Possible mechanism for non-BB-bar decays of the Upsilon (4S).

Recent observation of \ensuremath{\Upsilon}(4S)\ensuremath{\rightarrow}\ensuremath{\psi}+X with the \ensuremath{\psi} too energetic to come from the decay of a B meson suggests that there could be a substantial rate of non-BB\ifmmode\bar\else\textasciimacron\fi{} decay of \ensuremath{\Upsilon}(4S). We attempt to explain this by conventional quarkonium spectroscopy and suggest that \ensuremath{\Upsilon}(4S)\ensuremath{\rightarrow}${\mathit{h}}_{\mathit{b}}$(1P)+\ensuremath{\eta} and \ensuremath{\Upsilon}(4S)\ensuremath{\rightarrow}${\mathrm{\ensuremath{\eta}}}_{\mathit{b}}$+${\mathit{h}}_{1}$(1170) with subsequent decays into \ensuremath{\psi}'s are possible candidates. A crude estimate of the corresponding rates show them to be of the correct order of magnitude. The model implies that ${\mathit{h}}_{\mathit{b}}$ decays to DD\ifmmode\bar\else\textasciimacron\fi{} are more frequent than into the \ensuremath{\psi}, causing a potentially serious background to the sample used for determination of \ensuremath{\Vert}${\mathit{V}}_{\mathit{u}\mathit{b}}$/${\mathit{V}}_{\mathit{c}\mathit{b}}$\ensuremath{\Vert}.

Comments on beautiful baryons and on quarkonium

First we re-examine the mass estimates of beautiful baryons and show that, with the exception of one lattice QCD calculation, there is a consensus from general arguments and explicit models for a mass of the Λ b near 5.6 GeV. Second we make comments on quarkonium spectroscopy, stress the importance of observing the missing levels of the J/ψ and upsilon, discuss the implications of a recent theorem on level spacing, and make some remarks on toponium physics and the dramatic consequences of a very large mass of the top quark.

Quarkonium spectroscopy with vacuum polarization correction

The quarkonium spectroscopy has been studied by considering a non-relativistic potential which includes the QCD vacuum polarization corrections. The potential consists of a short-range 2-loop QCD potential matched to a Martin-type power law potential for large distances. The Poggio-Schnitzer correction to the leptonic decay width has also been included. The energy levels, leptonic decay widths and E1 transition rates ofψ and γ families have been calculated and have been found to be in good agreement with experimental results. The toponium spectroscopy has also been studied for the range ofM, values suggested by the recent jet events observed by the UA1 collaboration. The contribution of the decay through a virtualZ 0 has also been included in the calculation. The potential seems to provide a very good non-relativistic description of the quarkonium systems.