arXiv subjects
Publications and source records attributed to Mark B. Wise.
We compute the differential momentum correlation function for hadrons produced in the decay of $B$-mesons. This measure of hadronic event shapes tests the free $b$-quark decay picture for nonleptonic and semileptonic decays of $B$-mesons. Our results can also be applied to $B_s$ and $Λ_b$ decay.
An introduction to the heavy quark effective theory and its symmetries is given. Some implications of the heavy quark spin and flavor symmetries are discussed. Recent results on fragmentation to quarkonium states are reviewed.
The differential decay spectrum $dΓ/dE_e dq^2$ for the semileptonic decay of an unpolarized hadron containing a b-quark, and the decay spectrum $dΓ/dE_e dq^2 d\!\cosθ$ for polarized $Λ_b$ decay are computed to second order in the $1/m_b$ expansion. Most of the $1/m_b^2$ corrections have a simple physical interpretation, which is discussed in detail. The implications of the results for the determination of $V_{ub}$ are discussed. The decay spectra for semileptonic decay of hadrons containing a c-quark are also given. There is a subtlety in the use of the equations of motion at order $1/m_b^2$ in the heavy quark expansion which is explained.
The chiral and heavy quark symmetries of QCD are reviewed. These symmetries are used to predict some low-momentum properties of hadrons containing a single heavy quark. (Lectures given at the CCAST Symposium on Particle Physics at the Fermi Scale May27-June4,1993)
We discuss the fragmentation of a heavy quark to a baryon containing two heavy quarks of mass $m_Q\ggΛ_{\rm QCD}$. In this limit the heavy quarks first combine perturbatively into a compact diquark with a radius small compared to $1/Λ_{\rm QCD}$, which interacts with the light hadronic degrees of freedom exactly as does a heavy antiquark. The subsequent evolution of this $QQ$ diquark to a $QQq$ baryon is identical to the fragmentation of a heavy antiquark to a meson. We apply this analysis to the production of baryons of the form $ccq$, $bbq$, and $bcq$.
We calculate the polarisation of $ψ$'s and $Υ$'s produced by the fragmentation of heavy quarks. We find that fragmentation to transversely aligned quarkonium is slightly enhanced relative to longitudinally polarised. This net alignment corresponds to a $\sim 5\%$ asymmetry in the angular distribution of leptons produced in the subsequent decay of the quarkonium. We point out that the leading gluon contribution to $ψ$ and $Υ$ production arises from the evolution of the charm quark fragmentation function, rather than from direct gluon fragmentation.
Heavy quark symmetry relations for $B\rightarrow De\bar ν_e$ and $B\rightarrow D^*e \bar ν_e$ form factors receive corrections suppressed by powers of the charm quark mass. For small up and down quark massed the leading corrections of order $(1/m_c)^{n+2}~n = 0,1,2,...$ have a nonanalytic dependence on the light quark masses of the form $\ell n m_π^2$ for $n = 0$ and $(1/m_π)^n$ for $n = 1,2, ...$~. These corrections arise from very low momentum physics (i.e., well below the chiral symmetry breaking scale) and are computed using chiral perturbation theory. They are typically of order a few percent.
Microscopic black holes are sensitive to higher dimension operators in the gravitational action. We compute the influence of these operators on the Schwarzschild solution using perturbation theory. All (time reversal invariant) operators of dimension six are included (dimension four operators don't alter the Schwarzschild solution). Corrections to the relation between the Hawking temperature and the black hole mass are found. The entropy is calculated using the Gibbons-Hawking prescription for the Euclidean path integral and using naive thermodynamic reasoning. These two methods agree, however, the entropy is not equal to 1/4 the area of the horizon.
We show that QCD contains stable four-quark QQ\qbar\qbar hadronic states in the limit where the heavy quark mass goes to infinity. (Here Q denotes a heavy quark, \qbar a light antiquark and the stability refers only to the strong interactions.) The long range binding potential is due to one pion exchange between ground state Q\qbar mesons, and is computed using chiral perturbation theory. For the Q=b, this long range potential may be sufficiently attractive to produce a weakly bound two meson state.
Gronau and Wakaizumi have proposed a model in which the dominant $b$ decays are due to exchange of a new right-handed gauge boson. A test of this model via the study of polarized $Λ_b$ baryons produced in $e^+ e^- \to Z \to Λ_b + X$ is suggested.
We reconsider the recent derivation by de Rafael and Taron of bounds on the slope of the Isgur-Wise function. We argue that one must be careful to include cuts starting below the heavy meson pair production threshold, arising from heavy quark-antiquark bound states, and that if such cuts are properly accounted for then no constraints may be derived.
In the large $N_c$ limit, the $Λ_b$ and $Λ_c$ can be treated as bound states of chiral solitons and mesons containing a heavy quark. We show that the soliton and heavy meson are bound in an attractive harmonic oscillator potential. The Isgur-Wise function for $Λ_b\rightarrowΛ_c\, e^-\,\barν_e$ decay is computed in the large $N_c$ limit. Corrections to the form factor which depend on $m_N/ m_Q$ can be summed exactly ($m_N$ and $m_Q$ are the nucleon and heavy quark masses). We find that this symmetry breaking correction at zero recoil is only $1\%$.
The possibility of interpreting baryons containing a single heavy quark as bound states of solitons (that arise in the nonlinear sigma model) and heavy mesons is explored. Particular attention is paid to the parity of the bound states and to the role of heavy quark symmetry.
We calculate the decay rates for $\piee$, $\etaee$ and $\etamumu$ in chiral perturbation theory. The linear combination of counterterms necessary to render these amplitudes finite is fixed by the recently measured branching fraction for $\etamumu$. We find $\Br(\piee ) = 7\pm 1\times 10^{-8}$ and $\Br(\etaee )=5\pm 1\times 10^{-9}$.
Short distance physics involving virtual top and charm quarks contributes to $μ^+$ (and $μ^-$) polarization in the decay $K^+ \rightarrow π^+ μ^+ μ^-$. Measurement of the parity violating asymmetry $(Γ_R - Γ_L)/(Γ_R + Γ_L)$, where $Γ_R$ and $Γ_L$ are the rates to produce right and left-handed $μ^+$, may provide valuable information on the unitarity triangle. The parity violating asymmetry also gets a contribution from Feynman diagrams with two photon intermediate states. We estimate this two photon contribution to the asymmetry and discuss briefly the two photon contribution to time reversal odd asymmetries that involve both the $μ^+$ and $μ^-$ polarizations.