1,099 research outputs found

### Charmonium levels near threshold and the narrow state X(3872) \to \pi^{+}\pi^{-}\jpsi

We explore the influence of open-charm channels on charmonium properties, and
profile the 1:3D2, 1:3D3 and 2:1P1 charmonium candidates for X(3872). The
favored candidates, the 1:3D2 and 1:3D3 levels, both have prominent radiative
decays. The 1:3D2 might be visible in the $D^{0}\bar{D}^{*0}$ channel, while
the dominant decay of the 1:3D3 state should be into $D\bar{D}$. We propose
that additional discrete charmonium levels can be discovered as narrow
resonances of charmed and anticharmed mesons.Comment: 8 pages, 6 figures, uses RevTeX and boxedeps; few transcription
errors corrected in Tables IV and VI, three entries added in Table V, updated
references. Version to appear in Phys. Rev.

### Flavor Asymmetry of the Nucleon Sea: Consequences for Dilepton Production

Parton distributions derived from a chiral quark model that generates an
excess of down quarks and antiquarks in the proton's sea satisfactorily
describe the measured yields of muon pairs produced in proton-nucleus
collisions. Comparison of dilepton yields from hydrogen and deuterium targets
promises greater sensitivity to the predicted flavor asymmetry.Comment: 11 pages, REVTEX, (Three PostScript figures available by anonymous
ftp from fnth06.fnal.gov in directory /pub/Fermilab-Pub/92.264.)
FERMILAB-PUB-92/264--T LBL-3298

### 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
$B$-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

### Narrow Technihadron Production at the First Muon Collider

In modern technicolor models, there exist very narrow spin-zero and spin-one
neutral technihadrons---$pi^0_T$, $rho^0_T$ and $omega_T$---with masses of a
few 100 GeV. The large coupling of $\pi^0_T$ to $\mu^+\mu^-$, the direct
coupling of $rho^0_T$ and $omega_T$ to the photon and $Z^0$, 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

### Retardation Terms in The One-Gluon Exchange Potential

It is pointed out that the retardation terms given in the original
Fermi-Breit potential vanish in the center of mass frame. The retarded
one-gluon exchange potential is rederived in this paper from the
three-dimensional one-gluon exchange kernel which appears in the exact
three-dimensional relativistic equation for quark-antiquark bound states. The
retardation part of the potential given in the approximation of order $p^2/m^2$
is shown to be different from those derived in the previous literature. This
part is off-shell and does no longer vanish in the center of mass frame

### Hadronic Correlators from All-point Quark Propagators

A method for computing all-point quark propagators is applied to a variety of
processes of physical interest in lattice QCD. The method allows, for example,
efficient calculation of disconnected parts and full momentum-space 2 and 3
point functions. Examples discussed include: extraction of chiral Lagrangian
parameters from current correlators, the pion form factor, and the unquenched
eta-prime.Comment: LATTICE01(Algorithms and Machines

### Quarkonium Wave Functions at the Origin

We tabulate values of the radial Schr\"{o}dinger wave function or its first
nonvanishing derivative at zero quark-antiquark separation, for $c\bar{c}$,
$c\bar{b}$, and $b\bar{b}$ levels that lie below, or just above, flavor
threshold. These quantities are essential inputs for evaluating production
cross sections for quarkonium states.Comment: 9 pages, RevTeX, no figure

### 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 $p$-wave $B$, $B_s$, and
$D_s$ mesons. We generalize these results to higher excitations.Comment: 10 pages, FERMILAB--Pub--93/255--T (uses REVTEX macros

### Properties of the Charmed P-wave Mesons

Two broad charmed mesons, the D_0^* and D_1', have recently been observed. We
examine the quark model predictions for the D_0^* and D_1' properties and
discuss experimental measurements that can shed light on them. We find that
these states are well described as the broad, j=1/2 non-strange charmed P-wave
mesons. Understanding the D_0^* and D_1' states can provide important insights
into the D_{sJ}^*(2317), D_{sJ}(2460) states whose unexpected properties have
led to renewed interest in hadron spectroscopy.Comment: 7 pages. Some additional discussion and reference

### Can HERA See an $e u --> e c$ Signal of a Virtual Leptoquark?

Virtual leptoquarks could be detected at HERA through some nonstandard
effects. Here we explore the possibility that virtual leptoquarks could be
discovered via $e u --> e c$ scattering, assuming integrated luminosity of 200
pb$^{-1}$ and charm identification efficiency of 1%. We study the implications
of low energy data for the leptoquarks couplings and find that the most
relevant bound for the HERA cross sections comes from inclusive $c -->
e^+e^-~+~any$. This bound implies that the $e u --> e c$ cross sections for
virtual leptoquarks are just too small for observation of the signal. With an
improvement by a factor of ~2 on the luminosity or on charm identification it
could be possible to see virtual leptoquarks with {\it maximum couplings} up to
~1.5 - 2 TeV. However, the prospects for discovering the virtual particles if
their couplings are somewhat below present bounds are very dim. We point out
that this cross section could be very large for leptoquarks lighter than HERA's
kinematical limit, and if such a leptoquark is discovered we recommend
searching for a possible $e u --> e c$ signal. Our results may also serve as an
update on the maximum cross sections for leptoquark mediated $e u --> \mu c$
scattering.Comment: 15 Pages (LaTeX), including 4 postscript figures at the end of the
file. Feynman diagrams available by reques

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