arXiv subjects
Publications and source records attributed to Jonathan L. Rosner.
A resonance-like structure in the $π^\pm ψ(2S)$ mass spectrum arising in $B \to K π^\pm ψ(2S)$ has recently been reported. It is noted that the mass of this structure, $4433 \pm 4 \pm 1$ MeV, is not far from the threshold for production of $D^* \bar{D}_1(2420)$. A proposed mechanism for production of this state is suggested, and tests are suggested.
The recent observation of Sigma_b^{+-} (uub and ddb) and Xi_b^- (dsb) baryons at the Tevatron within 2 MeV of our theoretical predictions provides a strong motivation for applying the same theoretical approach, based on modeling the color hyperfine interaction, to predict the masses of other bottom baryons which might be observed in the foreseeable future. For S-wave qqb states we predict M(Omega_b) = 6052.1+-5.6 MeV, M(Omega^*_b) = 6082.8+-5.6 MeV, and M(Xi_b^0) = 5786.7 +- 3.0 MeV. For states with one unit of orbital angular momentum between the b quark and the two light quarks we predict M(Lambda_{b[1/2]}) = 5929+-2 MeV, M(Lambda_{b[3/2]}) = 5940+-2 MeV, M(Xi_{b[1/2]}) = 6106+-4 MeV, and M(Xi_{b[3/2]}) = 6115+-4 MeV.
The recent observation by CDF of Sigma_b^{+-} (uub and ddb) baryons within 2 MeV of the predicted Sigma_b - Lambda_b splitting has provided strong confirmation for the theoretical approach based on modeling the color hyperfine interaction. We now apply this approach to predict the masses of the Xi_b family of baryons with quark content usb and dsb - the ground state Xi_b at 5790 to 5800 MeV, and the excited states Xi_b^' and Xi_b^*. The main source of uncertainty is the method used to estimate the mass difference m_b - m_c from known hadrons. We verify that corrections due to the details of the interquark potential and to Xi_b-Xi_b^' mixing are small.
When CP asymmetries in $B^0(t)\to π^+ π^-$ are combined using broken flavor SU(3) with decay rates for $B^+\to K^0π^+$ and/or $B^0\to K^+π^-$, one can obtain stringent limits on the weak phase $γ$ which are consistent with those obtained from other CKM constraints. Experimental data in the past few years have improved to the extent that systematic errors associated with uncertainty in SU(3) symmetry breaking dominate the determination of $γ$. We obtain a value $γ=(73 \pm 4^{+10}_{-8})^\circ$, where the first error is statistical while the second one is systematic.
Developments reported at the 2007 Moriond Workshop on QCD and Hadronic Interactions are reviewed and placed in a theoretical context.
The generation of the fermion mass hierarchy in the standard model of particle physics is a long-standing puzzle. The recent discoveries from neutrino physics suggests that the mixing in the lepton sector is large compared to the quark mixings. To understand this asymmetry between the quark and lepton mixings is an important aim for particle physics. In this regard, two promising approaches from the theoretical side are grand unified theories and family symmetries. In this note we try to understand certain general features of grand unified theories with Abelian family symmetries by taking the simplest SU(5) grand unified theory as a prototype. We construct an SU(5) toy model with $U(1)_F \otimes Z'_2\otimes Z''_2 \otimes Z'''_2$ family symmetry that, in a natural way, duplicates the observed mass hierarchy and mixing matrices to lowest approximation. The system for generating the mass hierarchy is through a Froggatt-Nielsen type mechanism. One idea that we use in the model is that the quark and charged lepton sectors are hierarchical with small mixing angles while the light neutrino sector is democratic with larger mixing angles. We also discuss some of the difficulties in incorporating finer details into the model without making further assumptions or adding a large scalar sector.
New physics (NP) in charmless strangeness-changing $B$ and $B_s$ decays, which are dominated by the $b \to s$ penguin amplitudes, can either preserve isospin or change it by one unit. A general formalism is presented studying pairs of processes related to each other by isospin reflection. We discuss information on $ΔI$ in NP amplitudes, provided by time-integrated CP-violating rate asymmetries in $B^+$ and $B^0$ decays (or in $B_s$ decays), differences between rates for isospin-reflected processes, and coefficients $S$ of $\sin Δm t$ in time-dependent CP asymmetries. These four asymmetries in $B^+$ and $B^0$ decays (or five asymmetries in $B_s$ decays) are shown to determine the magnitude and CP-violating phase of a potential isovector NP amplitude, and the imaginary part of an isoscalar amplitude, assuming that strong phases in NP amplitudes are negligible. This information may be compared with predictions of specific models, for which we discuss a few examples.
Many new results on hadron spectra have been appearing in the past few years thanks to improved experimental techniques and searches in new channels. New theoretical techniques including refined methods of lattice QCD have kept pace with these developments. Much has been learned about states made of both light (u, d, and s) and heavy (c, b) quarks. The present review treats light-quark mesons, glueballs, hybrids, particles with a single c or b quark, charmonium, and bottomonium states. Some prospects for further study are noted.
The charged $Σ_b$ and $Σ^*_b$ states have recently been reported by the CDF Collaboration. The relation of their reported charge-averaged masses to expectations based on the quark model is reviewed briefly. A relation is proved among the $ΔI = 1$ electromagnetic mass differences $Σ_1 \equiv M(Σ^+) - M(Σ^-)$, $Σ^*_1 \equiv M(Σ^{*+})- M(Σ^{*-})$, $Σ_{b1} \equiv M(Σ_b^+) - M(Σ_b^-)$, and $Σ^*_{b1} \equiv M(Σ_b^{*+}) - M(Σ_b^{*-})$. The relation is $Σ^*_{b1} - Σ_{b1} = (m_s/m_b)(Σ^*_1 - Σ_1),$ leading to the expectation $Σ^*_{b1} - Σ_{b1} = 0.40 \pm 0.07$ MeV.
Some recent discoveries in the spectroscopy of hadrons containing heavy quarks, and some of their theoretical interpretations, are reviewed.
A sum rule relating the ratio $R_c = 2 Γ(B^+ \to K^+ π^0)/Γ(B^+ \to K^0 π^+)$ and the CP asymmetry $A_{CP}(B^+ \to K^+π^0)$ is proved to first order in the ratio of tree to penguin amplitudes. The sum rule explains why it is possible to have $R_c$ consistent with 1 together with a small CP asymmetry in $B^+ \to K^+ π^0$. The measured ratio $A_{CP}(B^+\to K^+π^0)/A_{CP}(B^0\to K^+π^-)$ rules out a small strong phase difference between a color-suppressed and a color-favored tree amplitude contributing to $B^+\to K^+π^0$ as favored by QCD factorization.
New rate measurements of $B^0$ decays into $π^0π^0, π^0η, π^0η', ηη, ηη', η'η'$ and $K^+ K^-$ are used in conjunction with flavor SU(3) to constrain the coefficients $S$ and $C$ of $\sinΔmt$ and $\cosΔmt$ in the time-dependent CP asymmetries of $B^0 \to η' K_S$ and $B^0 \to π^0 K_S$. Experimental values of $S_{η' K}$ are now seen to be closer to the Standard Model expectations, fully consistent with the new improved bounds.
This brief review traces the development of our understanding of the weak interactions, highlighting Jim Cronin's contributions through his studies of strange particle decays and the developments to which they led.
The opening of a new S-wave threshold is frequently accompanied by an abrupt dip in the magnitude of an amplitude for an already-open channel. One familiar example is the behavior of the I=0 S-wave $ππ$ scattering amplitude at $K \bar K$ threshold. Numerous other examples of this phenomenon in recent data are noted, and a unified description of the underlying dynamics is sought.
A definite relative phase and amplitude exists between the doubly-Cabibbo-% suppressed amplitude for $D^0 \to \ko M^0$ and the Cabibbo-favored amplitude for $D^0 \to \ok M^0$, where $M^0 = (π^0,η,η')$: $A(D^0 \to \ko M^0) = - \tan^2 θ_C A(D^0 \to \ok M^0)$. Here $θ_C$ is the Cabibbo angle. This relation, although previously recognized (for $M^0 = π^0$) as a consequence of the U-spin subgroup of SU(3), is argued to be less sensitive to corrections involving SU(3) breaking than related U-spin relations involving charged kaons or strange $D$ mesons. A corresponding relation between $D^+ \to \ko π^+$ and $D^+ \to \ok π^+$ is not predicted by U-spin. As a consequence, one expects the asymmetry parameters $R(D^0,M^0) \equiv [Γ(D^0 \to K_S M^0) - Γ(D^0 \to K_L M^0)/[Γ(D^0 \to K_S M^0) + Γ(D^0 \to K_L M^0)]$ each to be equal to $2 \tan^2 θ_C = 0.106$, in accord with a recent CLEO measurement $R(D^0) \equiv R(D^0,π^0) = 0.122 \pm 0.024 \pm 0.030$. No prediction for the corresponding ratio $R(D^+)$ is possible on the basis of U-spin.
New results on hadron spectra have been appearing in abundance in the past few years as a result of improved experimental techniques. These include information on states made of both light quarks (u, d, and s) and with one or more heavy quarks (c, b). The present review, dedicated to the memory of R. H. Dalitz, treats light-quark states, glueballs, hybrids, charmed and beauty particles, charmonium, and $b \bar b$ states. Some future directions are mentioned.
The observed violation of $A_{CP}(B^0 \to K^+ π^-) = A_{CP}(B^+ \to K^+ π^0)$ has been recently mentioned as a puzzle for the standard model. We point out that while this violation may be accounted for by a large color-suppressed tree amplitude, a sum rule involving three or four $B\to Kπ$ CP asymmetries should hold. The current experimental status of these sum rules and of a sum rule for $B\to Kπ$ decay rates is presented.
Methods are proposed for measuring the ratio $R^{+/0} = Γ(Υ(4S) \to B^+ B^-)/$ $Γ(Υ(4S) \to \bo \ob)$ without assuming isospin invariance in exclusive hadronic decays such as $B \to J/ψK$. The validity of isospin invariance in various B decays is discussed. Isospin violations are expected to be especially small in inclusive semileptonic decays, so that $Γ(B^+ \to X_c^0 \ell^+ ν_\ell) = Γ(B^0 \to X_c^- \ell^+ ν_\ell)$ is expected to hold at the sub-percent level. Suggestions are made for utilizing this relation. The accuracy of a ``double-tag'' method for obtaining $R^{+/0}$, such as that used for measuring the $D^+ D^-/D^0 \od$ ratio at the $ψ'' \equiv ψ(3770)$, is also estimated.