arXiv subjects
Publications and source records attributed to S. F. Tuan.
In this brief review, we examine carefully and critically the status of search for the $h_c$ [$ψ(1^1P_1)$] charmonium state and the $h_b$ [$Υ(1^1P_1)$] bottonium state, initiated by the E760 experiment. Recent experimental studies at CLEO/BABAR/BELLE are examined in the light of new theoretical and phenomenological understanding.
This report attempts to summarize the most interesting (and hopefully important) results leading up to and including those presented at the recent Symposium sponsored jointly by the Institute of Quantum Science at Nihon University and KEK. My task is to present the arguments on light-mass scalar mesons below 1 GeV from both theory and phenomenological viewpoints, including the new insight gained on $π-π$ production and scattering amplitudes. Specific topics are taken up, particularly on the existence of a $σ$(500-600) as explanation of the twin peak anomaly in $Υ(3S) \to Υ(1S)ππ$, the status of $J^{PC}=1^{-+}$ states and a possible crypto-exotic hybrid with $J^{PC}=0^{-+}$ are discussed, as well as the intriguing enhancement in $p\bar{p}$ radiative decay from $J/ψ$.
We have searched for conceptually simple extensions of the standard model, and describe here a candidate model which we find attractive. Our starting point is the assumption that off-diagonal CKM mixing matrix elements are directly related by lowest order perturbation theory to the quark mass matrices. This appears to be most easily and naturally implemented by assuming that all off-diagonal elements reside in the down-quark mass matrix. This assumption is in turn naturally realized by introducing three generations of heavy, electroweak-singlet down quarks which couple to the Higgs sector diagonally in flavor, while mass-mixing off-diagonally with the light down-quarks. Anomaly cancellation then naturally leads to inclusion of electroweak vector-doublet leptons. It is then only a short step to completing the extension to three generations of fundamental representations of E(6). Assuming only that the third generation B couples to the Higgs sector at least as strongly as does the top quark, the mass of the B is roughly estimated to lie between 1.7 TeV and 10 TeV, with lower-generation quarks no heavier. The corresponding guess for the new leptons is a factor two lower. Within the validity of the model, flavor and CP violation are ``infrared'' in nature, induced by semi-soft mass mixing terms, not Yukawa couplings. If the Higgs couplings of the new quarks are flavor symmetric, then there necessarily must be at least one ``oasis'' in the desert, induced by new radiative corrections to the top quark and Higgs coupling constants, and roughly at 1000 TeV.
The suggestion by Jaffe that if $σ$ is a light $q^{2}\bar{q}^{2}$ state $0^{++}$ then even the fundamental chiral transformation properties of the $σ$ becomes {\bf unclear}, has stimulated much interest. Adler pointed out that in fact the seminal work on chiral symmetry via PCAC consistency, is really quite consistent with the $σ$ being predominantly $q^{2}\bar{q}^{2}$. This interpretation was actually backed by subsequent work on effective Lagrangian methods for linear and non linear realizations. More recent work of Achasov suggests that intermediate four-quark states determine amplitudes involving other scalars $a_{0}(980)$ and $f_{0}(980)$ below 1 GeV, and the report by Ning Wu that study on $σ$ meson in $J/ψ\to ωπ^{+}π^{-}$ continue to support a non $q\bar{q}$ $σ$ with mass as low as 390 MeV. It is also noted that more recent re-analysis of $πK$ scattering by S. Ishida {\em et al.} together with the work of the E791 Collaboration, support the existence of the scalar $κ$ particle with comparatively light mass as well.
I review possible resolution of the $J/ψ(ψ^{\prime}) \to ρ-π$ puzzle based on two inputs: the relative phase between the one- photon and the gluonic decay amplitudes, and a possible hadronic excess in the inclusive nonelectromagnetic decay rate of $ψ^{\prime}$. The status of a universal large phase here is examined for its meaning and implications (including those for B-physics). Since the future of tau/charm facility(s) are again under consideration together with a future anti-proton facility at GSI, I propose to extend my review to include a broader discussion of charmonium physics. Outstanding questions like the status of the $^{1}P_{1}$ state of charmonium, measuring $D^{0}-\bar D^{0}$ mixing and relative strong phases, status of molecular P(S) - wave charmonia will also be discussed amongst others.
Recent experimental results on the decays of charmonium, together with related physics issues, are reviewed. Some future prospects are described.
After a brief historical background on the $\Ls$, we revisit the 25 year old controversy on whether $\Ls$ is a $qqq$ (L=1) three quark state or a $\K$ quasi virtual bound state. This work is stimulated by the recent suggestion of Isgur that s be treated as a heavy quark in heavy quark effective theory HQET. We re-examine the empirical evidence for minimal mixing amongst singlets and octets in negative parity baryon states, with a possible dynamical origin in the opening of inelastic threshold channels. Finally, we suggest that $\Ls$ belongs to a class of hadrons which are described simultaneously as $qqq$ or $q \bar{q}$ states and as hadronic bound states.
The recent BES Collaboration data on $ψ' \ra PV$, particularly the isospin violating mode $ψ' \ra π^0 ω^0$ and finding of a finite number for $B(ψ' \ra K^{*0}\bar{K}^0)$, enable us now to deal more precisely about the challenges to theory concerning this extraordinary and remarkable so called $ρ- π$ Puzzle of $J/ψ$ and $ψ'$ Decays. In terms of existing data, and deploying the simplest phenomenology, measurement of $ψ' \ra π^+π^-$ and whether a finite number for the $K^{*+} K^-$ mode might require a significantly larger accumulation of data, remain interesting questions.
Recent preliminary evidence for a $D \bar{D}$ state $χ(3.86)$ raises extremely interesting implications for theoretical models, particularly those currently in vogue, e.g. the flux tube model and a molecular charmonium picture. We examine the experimental consequences as well as the possible unveiling of a strata of C-exotic states in heavy quarkonia systems by future facilities like BES Upgrade/Tau-Charm Factory and CLEO III/B-Factories.
We argue that an experimental search for an $η_c'$, the first radial excitation of the $η_c(2980)$, may be carried out using the two photon process $e^+e^- \to e^+e^- γγ\ra e^+e^-η_c'$. We estimate the partial width $Γ_{γγ}(η_c')$ and the branching fraction $B(η_c' \to h)$, where $h$ is an exclusive hadronic channel, and find that for $h = K^o_s K^\pm π^\mp$ it may be possible to observe this state in two photon collisions at CLEO-II.
Here we discuss three separate topics in charmonium physics. (1) The Omicron \OMC as $1^{--}$ trigluonia, and the charmonium puzzle; the $η_c' (3600)$ search. (2) The decay $ψ(^1P_1) \to π^o + J/ψ$ and isospin violating charmonium decays. (3) How to search for $χ_c' = χ_c(2P)$ charmonium states.
The efforts of Roy-Sridhar-Close-Cho-Wise-Trivedi to resolve the CDF $ψ'$ anomaly with cascades from above-threshold $χ^\prime_c$ states require well defined signature states require well defined signatures [a small total width and a large branching fraction for $\cp \ra γ+ \pp]$ for the solution to be viable. Here we estimte the production of such states from $BR (B \ra \cp + X)BR (\cp \ra γ\pp)$ and $γγ$ production of $χ^\prime_{c2}$ at CLEO II, and comment on the feasbility of testing the hypothesis in terms of current experimental capabilities.