14,227 research outputs found
Constructing Confinement
The interaction between static quarks is derived by applying many-body
techniques to QCD in Coulomb gauge. The result is shown to be exact in the IR
and UV limits, and agrees remarkably well with lattice computations.Comment: 6 pages, 3 figures, proceedings for 2002 Lake Louise Winter Institut
Dynamics and Decay of Heavy-Light Hadrons
Recent signals for narrow hadrons containing heavy and light flavours are
compared with quark model predictions for spectroscopy, strong decays, and
radiative transitions. In particular, the production and identification of
excited charmed and cs states are examined with emphasis on elucidating the
nature of and states. Roughly 200 strong decay amplitudes of
and states up to 3.3 GeV are presented. Applications include determining
flavour content in mesons and the mixing angle in and wave
states and probes of putative molecular states. We advocate searching for
radially excited states in B decays.Comment: 19 pages, 7 figures, revtex. A numerical error is corrected. Some
strong decay rates have change
Modelling DNA Response to THz Radiation
Collective response of DNA to THz electric fields is studied in a simple pair
bond model. We confirm, with some caveats, a previous observation of
destabilising DNA breather modes and explore the parameter-dependence of these
modes. It is shown that breather modes are eliminated under reasonable physical
conditions and that thermal effects are significant.Comment: 6 pages, 3 figures. version to appear in Phys. Rev.
Radiation counting technique allows density measurement of metals in high-pressure/ high-temperature environment
Radioactive tracers induced by neutron irradiation provide a gamma ray flux proportional to the density of a metal, allowing density measurement of these metals in extreme high-temperature and high-pressure environments. This concept is applicable to most metals, as well as other substances
Hadron Loops: General Theorems and Application to Charmonium
In this paper we develop a formalism for incorporating hadron loops in the
quark model. We derive expressions for mass shifts, continuum components and
mixing amplitudes of "quenched" quark model states due to hadron loops, as
perturbation series in the valence-continuum coupling Hamiltonian. We prove
three general theorems regarding the effects of hadron loops, which show that
given certain constraints on the external "bare" quark model states, the
valence-continuum coupling, and the hadrons summed in the loops, the following
results hold: (1) The loop mass shifts are identical for all states within a
given N,L multiplet. (2) These states have the same total open-flavor decay
widths. (3) Loop-induced valence configuration mixing vanishes provided that
{\L}_i \neq \L_f or . The charmonium system is used as a
numerical case study, with the decay model providing the
valence-continuum coupling. We evaluate the mass shifts and continuum mixing
numerically for all 1S, 1P and 2S charmonium valence states due to loops of D,
D, D and D meson pairs. We find that the mass shifts are quite
large, but are numerically similar for all the low-lying charmonium states, as
suggested by the first theorem. Thus, loop mass shifts may have been "hidden"
in the valence quark model by a change of parameters. The two-meson continuum
components of the physical charmonium states are also found to be large,
creating challenges for the interpretation of the constituent quark model.Comment: 10 pages, 1 ps figure. Typos corrected; discussion of psi-eta_c mass
splitting added, published versio
Towards an Understanding of the New Charm and Charm-Strange Mesons
The observation of the D_{sJ}^*(2317), D_{sJ}(2460), and SELEX D^*_{sJ}(2632)
states with properties differing considerably from what was expected has led to
a renewed interest in hadron spectroscopy. In addition to these states,
non-strange partners of the D_{sJ} states have also been observed.
Understanding the D_0^* and D_1' states can provide important insights into the
D_{sJ} states. In this contribution I examine quark model predictions for the
D_0^* and D_1' states and discuss experimental measurements that can shed light
on them. I find that these states are well described as the broad, j=1/2
non-strange charmed P-wave mesons. In the latter part of this writeup I discuss
the c bar{s} possibilities for the SELEX D^*_{sJ}(2632) and measurements that
can shed light on it.Comment: Talk presented at the 1st Meeting of the APS Topical Group on
Hadronic Physics (Fermilab, Oct 24-26, 2004). 4 pages uses jpcon
Unquenching the Quark Model and Screened Potentials
The low-lying spectrum of the quark model is shown to be robust under the
effects of `unquenching'. In contrast, the use of screened potentials is shown
to be of limited use in models of hadrons. Applications to unquenching the
lattice Wilson loop potential and to glueball mixing in the adiabatic hybrid
spectrum are also presented.Comment: 6 pages, 3 ps figures, revtex. Version to appear in J. Phys.
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