arXiv subjects

Jonathan L. Rosner

Publications and source records attributed to Jonathan L. Rosner.

At least 235 records · Page 13Linked to original sources

arXiv1997

B Decays Involving $η$ and $η'$ in the Light of the $B \to K η'$ Process

The observation by the CLEO Collaboration of the decays $B^{(+,0)} \to K^{(+,0)} η'$ is shown to imply a significant but still uncertain contribution from the flavor-SU(3)-singlet component of the $η'$. By comparing the rate for these decays with others for decays of B mesons to two pseudoscalar mesons, it is shown that the prospects for observing CP-violating asymmetries in certain modes such as $B^+ \to π^+ η$ and $B^+ \to π^+ η'$ are quite bright.

hep-ph↗

arXiv1997

B Decays to Charmless VP Final States

The CLEO Collaboration has now observed the decays $B^+ \to ωπ^+$ and $B \to ωK^+$ with branching ratios of $(1.1^{+0.6}_{-0.5} \pm 0.2) \times 10^{-5}$ and $(1.5^{+0.7}_{-0.6} \pm 0.3) \times 10^{-5}$, respectively. These are the first reported decays to charmless final states involving a vector (V) and a pseudoscalar (P) meson. The implications of these decays for others of B mesons to charmless VP final states are explored. In a model-independent approach, using only flavor SU(3) symmetry, several tests are proposed for an anticipated hierarchy among different contributions to decay amplitudes.

hep-ph↗

arXiv1997

New Developments in Precision Electroweak Physics

Our picture of the electroweak interactions continues to improve, with ever more precise constraints on the masses of the Higgs boson(s) and on non-standard physics. Some recent developments include: (a) a calculation of higher-order effects on the weak mixing angle which reduces scheme-dependence, (b) a long-awaited improvement in the experimental accuracy of measurement of parity violation in atomic cesium, and (c) improvements in top quark and $W$ mass measurements from Fermilab and $W$ mass measurements from LEP.

hep-ph↗

arXiv1997

Detection of the RF Pulse Associated With Cosmic Ray Air Showers

Initial results of a project to detect the radio-frequency pulse associated with extensive air showers of cosmic rays are described briefly. This work is being performed at the CASA/MIA array in Utah, with the intention of designing equipment that can be used in conjunction with the Auger Giant Array proposal.

hep-ex↗

arXiv1997

Top Quark Mass

The influence of the top quark mass on mixing processes and precise electroweak measurements is described. Experimental observation of the top quark in proton-antiproton collisions is discussed, and some brief remarks are made about electron-positron production. Some speculations are noted about the possible significance of the large top quark mass.

hep-ph↗

arXiv1996

CKM Matrix and Standard-Model CP Violation

The currently favored model of CP violation is based on phases in the Cabibbo-Kobayashi-Maskawa (CKM) matrix describing the weak charge-changing couplings of quarks. The present status of parameters of this matrix is described. Tests of the theory, with particular emphasis on the study of B meson decays, are then noted. Some remarks are made regarding the possible origin of the baryon asymmetry of the universe; the corresponding coupling pattern of the leptons could shed light on the question. Some possibilities for non-standard physics are discussed.

hep-ph↗

arXiv1996

An E$_6$ interpretation of an $e^+ e^- γγE\!\!\!/_T$ event

The lowest-dimensional representation of the group E$_6$ contains both the standard quarks and leptons and a set of exotic quarks and leptons whose decays can involve a series of chains ending in radiative decay of one light neutrino species to another. An example is given based on the decomposition E$_6 \to$ SU(2)$_I \times$ SU(6), where SU(2)$_I$ is an ``inert'' subgroup whose gauge bosons $W_I^{(\pm)}$ and $Z_I$ are all electromagnetically neutral, while SU(6) contains the conventional SU(5) grand-unified group. The possibility is explored that such a chain is responsible for an event observed by the Collider Detector at Fermilab (CDF) involving the production in proton-antiproton collisions at $E_{\rm c.m.} = 1.8$ TeV of an electron-positron pair, two photons, and missing energy ($e^+ e^- γγE \!\!\!/_T$).

hep-ph↗

arXiv1996

Prominent Decay Modes of a Leptophobic Z'

An anomaly-free U(1) charge $Q'$ has recently been identified within the group E$_6$ for which the familiar leptons (the left- and right-handed electron and the left-handed neutrino) have $Q' = 0$. It is pointed out that the $Q'$ charges of several {\it exotic} leptons within E$_6$ matter multiplets are quite large, leading to the prediction that half of the decays of the so-called ``leptophobic'' $Z'$ bosons coupling to $Q'$ are to these exotic leptons. Other large $Q'$ charges include those of standard up-type quarks and exotic down-type quarks. Substantial forward-backward asymmetries are expected in $u \bar u \to Z' \to f \bar f$ channels when $f$ is a standard up-type quark, an exotic down-type quark, or an exotic lepton.

hep-ph↗

arXiv1996

Universal Spacing for Heavy Quarkonium Dissociation

When a heavy quark and the corresponding antiquark are separated by more than $1.4 - 1.5$ fm, it becomes energetically favorable for a light quark-antiquark pair to be produced, leading to fragmentation into a pair of flavored mesons. The relation of this critical quark separation to other dimensional constants of the strong interactions (such as the pion decay constant, the QCD scale, and the light-quark constituent mass) is discussed.

hep-ph↗

arXiv1996

Discrete Ambiguities In Extracting Weak Phases from B decays

Phases of elements of the Cabibbo-Kobayashi-Maskawa (CKM) matrix, as obtained using decays of $B$ mesons to $π^+ π^-$, $π^\pm K^\mp$, and $π^+ K^0$ or $π^- \overline{K}^0$, are shown to have a class of discrete ambiguities. In most cases these can be eliminated using other information on CKM phases.

hep-ph↗

arXiv1996

Two Topics in $b$ Physics

(1) A simple transversity analysis permits one to separate the P-even and P-odd partial waves in such decays as $B_s \to J/ψϕ$ and $B \to J/ψK^*$. This method is relevant to the separation of contributions of CP-even and CP-odd final states in $B_s$ decays, and hence to the measurement of a possible lifetime difference between mass eigenstates. (2) The enhancement $ΔΓ(Λ_b)$ of the $Λ_b$ decay rate due to four-fermion processes is calculated in terms of the $Σ_b^* - Σ_b$ hyperfine splitting, the $B^* - B$ hyperfine splitting, and the $B$ meson decay constant $f_B$. Despite a relatively large hyperfine splitting observed by the DELPHI Collaboration, the mechanism falls far short of being able to explain the observed enhancement.

hep-ph↗

arXiv1996

Weak Phases From B Decays to Kaons and Charged Pions

Phases of elements of the Cabibbo-Kobayashi-Maskawa (CKM) matrix can be obtained using decays of $B$ mesons to $π^+ π^-$, $π^\pm K^\mp$, and $π^+ K^0$ or $π^- \overline{K}^0$. For $B^0~{\rm or}~ \overline{B}^0 \to π^+ π^-$, one identifies the flavor of the neutral $B$ meson at time of production and studies the time-dependence of the decay rate. The other processes are self-tagging and only their rates need be measured. By assuming flavor SU(3) symmetry and first-order SU(3) breaking, one can separately determine the phases $γ\equiv {\rm Arg}~V_{ub}^*$ and $α= π- β- γ$, where $β\equiv {\rm Arg}~V_{td}^*$. Special cases include the vanishing of strong interaction phase differences between amplitudes, the possibility of recovering partial information when $π^+ π^-$ and $π^\pm K^\mp$ decays cannot be distinguished from one another, and the use of a correlation between $γ$ and $α$ in the region of allowed parameters.

hep-ph↗

arXiv1996

$V_{td}$ from Hadronic Two-Body $B$ Decays

Certain hadronic two-body decays of $B$ mesons are dominated by penguin diagrams. The ratios of rates for several such decays, including $Γ(B^0 \to \overline{K}^{*0} K^0)/Γ(B^0 \to ϕK^0)$, $Γ(B^0 \to \overline{K}^{*0} K^{*0})/Γ(B^0 \to ϕK^{*0})$, $Γ(B^+ \to \overline{K}^{*0} K^+)$ $/Γ(B^+ \to ϕK^+)$, and $Γ(B^+ \to \overline{K}^{*0} K^{*+})/Γ(B^+ \to ϕK^{*+})$, can provide information on the ratio of Cabibbo-Kobayashi-Maskawa (CKM) elements $|V_{td}/V_{ts}|$ in a manner complementary to other proposed determinations. SU(3) breaking effects cancel in some ratios. The cases of neutral $B$ decays are free of corrections from small annihilation terms.

hep-ph↗

arXiv1996

Enhancement of the $Λ_b$ decay rate

The enhancement $ΔΓ(Λ_b)$ of the $Λ_b$ decay rate due to four-fermion processes of weak scattering and Pauli interference is calculated within the quark model. An estimate of the relative $bu$ wave function at zero separation, $|Ψ(0)|^2_{bu}$, is obtained in terms of the $Σ_b^* - Σ_b$ hyperfine splitting, the $B^* - B$ hyperfine splitting, and the $B$ meson decay constant $f_B$. For $M(Σ_b^*) - M(Σ_b) = 56 \pm 16$ MeV, $M(B^*) - M(B) = 46$ MeV, and $f_B = 190 \pm 40$ MeV, we find $ΔΓ(Λ_b) = (0.025 \pm 0.013)$ ps$^{-1}$, to be compared with the observed enhancement $Γ(Λ_b) - Γ(B^0) = 0.20 \pm 0.05$ ps$^{-1}$. Even such a meager enhancement entails a value of $|Ψ(0)|^2_{bu}$ considerably larger than the corresponding value of $|Ψ(0)|^2_{cd}$ in the $Λ_c$ baryon.

hep-ph↗

arXiv1995

Forward-Backward Asymmetries in Hadronically Produced Lepton Pairs

It has now become possible to observe appreciable numbers of hadronically produced lepton pairs in mass ranges where the contributions of the photon and $Z^0$ are comparable. Consequently, in the reaction $p \bar p \to \ell^- \ell^+ + \ldots$, substantial forward-backward asymmetries can be seen. These asymmetries provide a test of the electroweak theory in a new regime of energies, and can serve as diagnostics for any new neutral vector bosons coupling both to quarks and to charged lepton pairs.

hep-ph↗

arXiv1995

Angular distributions and lifetime differences in $B_s \to J/ψϕ$ decays

The strange $B$ meson $B_s \equiv \bar b s$ and its charge-conjugate $\bar B_s \equiv b \bar s$ are expected to mix with one another in such a way that the mass eigenstates $B_s^H$ (``heavy'') and $B_s^L$ (``light'') may have a perceptible lifetime difference of up to 40\%, with the CP-even eigenstate being shorter-lived. A simple transversity analysis permits one to separate the CP-even and CP-odd components of $B_s \to J/ψϕ$, and thus to determine the lifetime difference. The utility of a similar analysis for $B^0 \to J/ψK^{*0}$ is noted.

hep-ph↗

arXiv1995

Determining the CKM Unitarity Triangle From $B$ Decays to Charged Pions and Kaons

Decay rates of $B^0(t)\toπ^+π^-,~B^0\toπ^- K^+,~B^+\toπ^+ K^0~ (K_S\toπ^+π^-$) and of charge-conjugate processes are studied within flavor SU(3) symmetry and first-order SU(3) breaking. We show that these measurements can determine with a reasonable accuracy the two angles, $α$ and $γ$, of the Cabibbo-Kobayashi-Maskawa unitarity triangle.

hep-ph↗

arXiv1995

Table-Top Time Reversal Violation

Many electrical and mechanical systems with two normal modes are appropriate for illustrating the quantum mechanics of neutral kaons. The illustration of CP- or time-reversal-violation in the neutral kaon system by mechanical or electrical analogues is more subtle. Some possibilities which could be realized in a table-top demonstration are suggested.

hep-ph↗