1,097 research outputs found

    Narrow Technihadron Production at the First Muon Collider

    Get PDF
    In modern technicolor models, there exist very narrow spin-zero and spin-one neutral technihadrons---piT0pi^0_T, rhoT0rho^0_T and omegaTomega_T---with masses of a few 100 GeV. The large coupling of πT0\pi^0_T to ÎŒ+Ό−\mu^+\mu^-, the direct coupling of rhoT0rho^0_T and omegaTomega_T to the photon and Z0Z^0, and the superb energy resolution of the First Muon Collider may make it possible to resolve these technihadrons and produce them at extraordinarily large rates.Comment: 11 pages, latex, including 2 postscript figure

    B-Meson Gateways to Missing Charmonium Levels

    Full text link
    We outline a coherent strategy for exploring the four remaining narrow charmonium states [\eta_{c}^{\prime}(2\slj{1}{1}{0}), h_{c}(1\slj{1}{2}{1}), \eta_{c2}(1\slj{1}{3}{2}), and \psi_{2}(1\slj{3}{3}{2})] expected to lie below charm threshold. Produced in BB-meson decays, these levels should be identifiable \textit{now} via striking radiative transitions among charmonium levels and in exclusive final states of kaons and pions. Their production and decay rates will provide much needed new tests for theoretical descriptions of heavy quarkonia.Comment: 5 pages, uses ReVTeX and BibTe

    The Search for Beauty-fully Bound Tetraquarks Using Lattice Non-Relativistic QCD

    Get PDF
    Motivated by multiple phenomenological considerations, we perform the first search for the existence of a bˉbˉbb\bar{b}\bar{b}bb tetraquark bound state with a mass below the lowest non-interacting bottomonium-pair threshold using the first-principles lattice non-relativistic QCD methodology. We use a full SS-wave colour/spin basis for the bˉbˉbb\bar{b}\bar{b}bb operators in the three 0++0^{++}, 1+−1^{+-} and 2++2^{++} channels. We employ four gluon field ensembles at multiple lattice spacing values ranging from a=0.06−0.12a = 0.06 - 0.12 fm, all of which include uu, dd, ss and cc quarks in the sea, and one ensemble which has physical light-quark masses. Additionally, we perform novel exploratory work with the objective of highlighting any signal of a near threshold tetraquark, if it existed, by adding an auxiliary potential into the QCD interactions. With our results we find no evidence of a QCD bound tetraquark below the lowest non-interacting thresholds in the channels studied.Comment: 24 Pages; 19 Figures; Accepted By PRD; Unaveraged Correlator Data Publicly Available in SQLite Databas

    Properties of Orbitally Excited Heavy-Light Mesons

    Full text link
    Orbitally excited heavy-light mesons are potentially important as tools for tagging the flavors and momenta of ground-state pseudoscalars detected through weak decays. We use heavy-quark symmetry supplemented by insights gleaned from potential models to estimate masses and widths of pp-wave BB, BsB_s, and DsD_s mesons. We generalize these results to higher excitations.Comment: 10 pages, FERMILAB--Pub--93/255--T (uses REVTEX macros

    Vacuum Alignment in Technicolor Theories-I. The Technifermion Sector

    Get PDF
    We have carried out numerical studies of vacuum alignment in technicolor models of electroweak and flavor symmetry breaking. The goal is to understand alignment's implications for strong and weak CP nonconservation in quark interactions. In this first part, we restrict our attention to the technifermion sector of simple models. We find several interesting phenomena, including (1) the possibility that all observable phases in the technifermions' unitary vacuum-alignment matrix are integer multiples of \pi/N' where N' \le N, the number of technifermion doublets, and (2) the possibility of exceptionally light pseudoGoldstone technipions.Comment: 19 pages, Latex with one postscript figur

    Two-gluon coupling and collider phenomenology of color-octet technirho mesons

    Get PDF
    It has recently been suggested that gauge invariance forbids the coupling of a massive color-octet vector meson to two gluons. While this is true for operators in an effective Lagrangian of dimension four or less, we demonstrate that dimension six interactions will lead to such couplings. In the case of technicolor, the result is a technirho-gluon-gluon coupling comparable to the naive vector meson dominance estimate, but with a substantial uncertainty. This has implications for several recent studies of technicolor phenomenology.Comment: 6 pages, LaTeX; added a referenc

    Heavy Quarkonium Melting in Large N Thermal QCD

    Full text link
    Large N QCD is mostly governed by planar diagrams and should show linear confinement when these diagrams are suitably summed. The linear confinement of quarks in a class of these theories using gravity duals that capture the logarithmic runnings of the coupling constants in the IR and strongly coupled asymptotic conformal behavior in the UV was studied in our previous work. We also extended the theories to high temperatures and argued the possibilities of meltings and suppressions of heavy quarkonium states. In this paper we give a formal proof of melting using very generic choices of UV completions, and point out some subtleties associated with meltings in generic large N theories. Our proof requires only the existence of well defined UV behaviors that are devoid of Landau poles and UV divergences of the Wilson loops, allowing degrees of freedom to increase monotonously with energy scale. We determine the melting temperatures of heavy quarkonium states, which could suggest the presence of deconfinement phase transitions in these theories.Comment: 15 pages, LaTex file, 6 eps figures; v2: typos corrected and references added; v3: some additional typos corrected, and the draft slightly enlarged. Final version to appear in Physics Letters

    Perturbation Theory for Fat-link Fermion Actions

    Get PDF
    We discuss weak coupling perturbation theory for lattice actions in which the fermions couple to smeared gauge links. The normally large integrals that appear in lattice perturbation theory are drastically reduced. Even without detailed calculation, it is easy to determine to good accuracy the scale of the logarithms that appear in cases where an anomalous dimension is present. We describe several 1-loop examples for fat-link Wilson and clover fermions. including the additive mass shift, the relation between the lattice and MSbar quark masses, and the axial current renormalization factor (ZAZ_A) for light-light and static-light currents.Comment: LATTICE99(Improvement and Renormalization); 3 pages, no figure

    Charmonium states in QCD-inspired quark potential model using Gaussian expansion method

    Full text link
    We investigate the mass spectrum and electromagnetic processes of charmonium system with the nonperturbative treatment for the spin-dependent potentials, comparing the pure scalar and scalar-vector mixing linear confining potentials. It is revealed that the scalar-vector mixing confinement would be important for reproducing the mass spectrum and decay widths, and therein the vector component is predicted to be around 22%. With the state wave functions obtained via the full-potential Hamiltonian, the long-standing discrepancy in M1 radiative transitions of J/ψJ/\psi and ψâ€Č\psi^{\prime} are alleviated spontaneously. This work also intends to provide an inspection and suggestion for the possible ccˉc\bar{c} among the copious higher charmonium-like states. Particularly, the newly observed X(4160) and X(4350) are found in the charmonium family mass spectrum as M(21D2)=4164.9M(2^1D_2)= 4164.9 MeV and M(33P2)=4352.4M(3^3P_2)= 4352.4 MeV, which strongly favor the JPC=2−+,2++J^{PC}=2^{-+}, 2^{++} assignments respectively. The corresponding radiative transitions, leptonic and two-photon decay widths have been also predicted theoretically for the further experimental search.Comment: 16 pages,3 figure

    Chiral Multiplets of Heavy-Light Mesons

    Full text link
    The recent discovery of a narrow resonance in D_s+pi^0 by the BABAR collaboration is consistent with the interpretation of a heavy J^P(0+,1+) spin multiplet. This system is the parity partner of the groundstate (0-,1-) multiplet, which we argue is required in the implementation of SU(3)_L x SU(3)_R chiral symmetry in heavy-light meson systems. The (0+,1+)->(0-,1-)+pi transition couplings satisfy a Goldberger-Treiman relation, g_pi = Delta(M)/f_pi, where Delta(M) is the mass gap. The BABAR resonance fits the 0+ state, with a kinematically blocked principal decay mode to D+K. The allowed D_s+pi, D_s+2pi and electromagnetic transitions are computed from the full chiral theory and found to be suppressed, consistent with the narrowness of the state. This state establishes the chiral mass difference for all such heavy-quark chiral multiplets, and precise predictions exist for the analogous B_s and strange doubly-heavy baryon states.Comment: 10 pages; minor editorial revisions; recomputed M1 transitio
    • 

    corecore