122774915
Heavy quark spin symmetry and heavy hadronic molecules
In the heavy quark limit there is heavy quark spin symmetry. As a consequence, heavy hadrons or heavy quarkonia form spin multiplets. We argue that due to the symmetry, also heavy flavor hadronic molecules form spin multiplets, and the hyperfine splittings are the same as those between the heavy hadrons which are components of the molecules. Hence it provides a method to identify the nature of heavy hadronic molecules. As an example, we give predictions of the properties of an ηc′f0(980) bound state assuming the Y(4660) to be an S‐wave ψ′f0(980) shallow bound state. We also show that the enhancement observed in the Λc+Λc− invariant mass distribution might be the Y(4660).
118512241
Enhanced breaking of heavy quark spin symmetry
Abstract Heavy quark spin symmetry is useful to make predictions on ratios of decay or production rates of systems involving heavy quarks. The breaking of spin symmetry is generally of the order of O ( Λ QCD / m Q ) , with Λ QCD the scale of QCD and m Q the heavy quark mass. In this paper, we will show that a small S - and D -wave mixing in the wave function of the heavy quarkonium could induce a large breaking in the ratios of partial decay widths. As an example, we consider the decays of the ϒ ( 10 860 ) into the χ b J ω ( J = 0 , 1 , 2 ) , which were recently measured by the Belle Collaboration. These decays exhibit a huge breaking of the spin symmetry relation were the ϒ ( 10 860 ) a pure 5 S bottomonium state. We propose that this could be a consequence of a mixing of the S -wave and D -wave components in the ϒ ( 10 860 ) . Prediction on the ratio Γ ( ϒ ( 10 860 ) → χ b 0 ω ) / Γ ( ϒ ( 10 860 ) → χ b 2 ω ) is presented assuming that the decay of the D -wave component is dominated by the coupled-channel effects.
56107005
HEAVY QUARK SYMMETRIES: MOLECULAR PARTNERS OF THE X(3872) AND $Z_{b}(10610)/Z_{b}'(10650)$
In this work, we have used an Effective Field Theory (EFT) framework based on Heavy Quark Spin (HQSS), Heavy Flavour (HFS) and Heavy Antiquark-Diquark symmetries (HADS). Using a standard lagrangian for the heavy meson-heavy antimeson system, we fit the counter-terms of the model to predict some promising experimental data that can be interpreted as heavy meson-heavy antimeson molecules, that is, the X(3872) and the . Next, and, taking advantage of HADS, we use the same lagrangian to explore the consequences for heavy meson-doubly heavy baryon molecules, which can also be interpreted as triply heavy pentaquarks.
119444672
Dynamically generated 0+ heavy mesons in a heavy chiral unitary approach
In terms of the heavy chiral Lagrangian and the unitarized coupled-channel scattering amplitude, interaction between the heavy meson and the light pseudoscalar meson is studied. By looking for the pole of scattering matrix on an appropriate Riemann sheet, a DK bound state D-s0* with the mass of 2.312 +/- 0.041 GeV is found. This state can be associated as the narrow D*(sJ)(2317) state found recently. In the same way, a B (K) over bar bound state B* is found, and its mass of 5.725 +/- 0.039 GeV is predicted. The spectra of D-0* and B-0* with I = 1/2 are further investigated. One broad and one narrow states are predicted in both charm and bottom sectors. The coupling constants and decay widths of the predicted states are also calculated. (c) 2006 Elsevier B.V. All rights reserved.
18261577
Light quark mass dependence in heavy quarkonium physics.
The issue of chiral extrapolations in heavy quarkonium systems is discussed. We show that the light quark mass dependence of the properties of heavy quarkonia is not always suppressed. For quarkonia close to an open flavor threshold, even a nonanalytic chiral extrapolation is needed. Both these nontrivial facts are demonstrated to appear in the decay widths of the hindered M1 transitions between the first radially excited and ground state P-wave charmonia. The results at a pion mass of about 500 MeV could deviate from the value at the physical pion mass by a factor of two. Our findings show the necessity of performing chiral extrapolations for lattice simulations of heavy quarkonium systems. Furthermore, lattice calculations of these transitions would also provide a definite answer to the role of coupled-channel effects in heavy quarkonium physics due to virtual heavy mesons.
573483
Examining coupled-channel effects in radiative charmonium transitions.
Coupled-channel effects due to coupling of charmonia to the charmed and anticharmed mesons are of current interest in heavy quarkonium physics. However, the effects have not been unambiguously established. In this Letter, a clean method is proposed in order to examine the coupled-channel effects in charmonium transitions. We show that the hindered M1 radiative transitions from the 2P to 1P charmonia are suitable for this purpose. We suggest to measure one or more of the ratios Γ(h(c)'→χ(cJ)γ)/Γ(χ(cJ)'→χ(cJ)π(0)) and Γ(χ(cJ)'→h(c)γ)/Γ(χ(cJ)'→χ(cJ)π(0)), for which highly nontrivial and parameter-free predictions are given. The picture can also be tested using both unquenched and quenched lattice calculations.
116987222
Ratio method of measuring W boson mass
This dissertation describes an alternative method of measuring the W boson mass in D0 experiment. Instead of extracting M{sub W} from the fitting of W {yields} e{nu} fast Monte Carlo simulations to W {yields} e{nu} data as in the standard method, we make the direct fit of transverse mass between W {yields} e{nu} data and Z {yields} ee data. One of the two electrons from Z boson is treated as a neutrino in the calculation of transverse mass. In ratio method, the best fitted scale factor corresponds to the ratio of W and Z boson mass (M{sub W}/M{sub Z}). Given the precisely measured Z boson mass, W mass is directly fitted from W {yields} e{nu} and Z {yields} ee data. This dissertation demonstrates that ratio method is a plausible method of measuring the W boson mass. With the 1 fb{sup -1} D0 Run IIa dataset, ratio method gives M{sub W} = 80435 {+-} 43(stat) {+-} 26(sys) MeV.