1,096 research outputs found
Narrow Technihadron Production at the First Muon Collider
In modern technicolor models, there exist very narrow spin-zero and spin-one
neutral technihadrons---, and ---with masses of a
few 100 GeV. The large coupling of to , the direct
coupling of and to the photon and , 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
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
-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
Motivated by multiple phenomenological considerations, we perform the first
search for the existence of a 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
-wave colour/spin basis for the operators in the three
, and channels. We employ four gluon field ensembles
at multiple lattice spacing values ranging from fm, all of
which include , , and 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
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 -wave , , and
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
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
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
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
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 () 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
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 and are alleviated
spontaneously. This work also intends to provide an inspection and suggestion
for the possible 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 MeV and MeV, which strongly favor the 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
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
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