arXiv subjects

Abner Soffer

Publications and source records attributed to Abner Soffer.

30 records · Page 2Linked to original sources

arXiv2009

CP-violation parameters from decay rates of $B^\pm \to D K^\pm$, $D\to$ multibody final states

We describe a method for measuring CP-violation parameters from which the Cabibbo-Kobayashi-Maskawa angle $γ$ may be extracted. The method makes use of the total decay rates in $B^\pm \to DK^\pm$ decays, where the neutral $D$ meson decays to multibody final states. We analyze the error of the method using experimental CP-violation analysis variables that enable straightforward sensitivity comparison with other methods for extracting $γ$, and discuss the use of $B$-factory and charm-factory data to obtain the relevant charm decay information needed for this measurement. Measurement sensitivities are estimated for the currently available $B$-factory data sample, and $D$ decay modes for which use of this method can make a significant contribution toward reducing the total error on $γ$ are identified.

hep-ph↗

arXiv2008

Estimate of the branching fraction $τ^- \to ηπ^-ν_τ$, the $a_0^-(980)$, and non-standard weak interactions

We consider the ``second-class current'' decay $τ^-\toπ^-ην_τ$ from several points of view. We first focus on the decay rate as expected within standard weak interaction and QCD due to isospin violation. The decay contributions divide into $P$- and $S$-wave parts. The former can be reliably estimated using the $ρηπ$ coupling inferred from the rates and Dalitz-plot distributions of $η\to 3π$ decays. The somewhat larger $S$-wave part, which was previously computed using chiral perturbation theory, is estimated from a simple $\bar qq$ model. Both estimates of the $S$-wave part depend on whether the $a_0(980)$ scalar particle is a $\bar qq$ or some other (4-quark) state. Finally, we discuss genuinely new, non-$V-A$ scalar weak interactions. The $τ^-\toπ^-ην_τ$ decay provides information on this question, which nicely complements that from precision $β$ decay experiments. % In summary, we discuss the possible implications of putative values of the branching fraction ${\cal B}(τ^-\toπ^-ην_τ)$. In the case of larger values, in particular of the $S$-wave part, not only will detection of the decay be more likely and more reliable, its implications will be more far-reaching and interesting.

hep-ph↗

arXiv2008

Isospin analysis of D0 decay to three pions

The final state of the decay D0 --> pi+ pi- pi0 is analyzed in terms of isospin eigenstates. It is shown that the final state is dominated by the isospin-0 component. This suggests that isospin considerations may provide insight into this and perhaps other $\Dz$-meson decay. We also discuss the isospin nature of the nonresonant contribution in the decay, which can be further understood by studying the decay D0 --> pi0 pi0 pi0.

hep-ph↗

arXiv2005

Improved measurement of (2 beta+gamma)

We propose to measure the Cabibbo-Kobayashi-Maskawa parameter (2 beta+gamma) using B^0 decays involving several intermediate states, and describe a general formalism that applies to a broad class of decays. The main advantage of this method is that the ratios between the interfering amplitudes can be measured without requiring external input. In addition, discrete ambiguities are resolved.

hep-ph↗

arXiv2005

The Effect of $D-\bar D$ Mixing on the Measurement of $γ$ in $B\to D K$ Decays

$D-\bar D$ mixing is the source of the largest theoretical uncertainty in the extraction of $γ$ from $B\to D K$ decays. In the Standard Model, the mixing can have a rate close to its current experimental upper bound and is CP-conserving to an excellent approximation. We show that neglecting CP-conserving $D-\bar D$ mixing leads to an error in the determination of $γ$ only at second order in the small parameters, $Δm_D/Γ_D$ and $ΔΓ_D/Γ_D$, and is therefore very small and can be safely neglected.

hep-ph↗

arXiv2003

Determination of the angle gamma using multibody D decays in B^+- -> D K^+-

We describe a method for determining gamma using B^+- -> D K^+- decays followed by a multibody D decay. In the talk we focus on K_S pi^- pi^+ final state, but other modes such as D -> K_S K^- K^+ and D -> K_S pi^- pi^+ pi^0 can also be used. The main advantages of the method are that it uses only Cabibbo allowed D decays, and that large strong phases are expected due to the presence of resonances. Since no knowledge about the resonance structure is needed, gamma can be extracted without any hadronic uncertainty.

hep-ph↗

arXiv2003

Determining $γ$ using $B^\pm \to D K^\pm$ with multibody D decays

We propose a method for determining $γ$ using $B^\pm\to D K^\pm$ decays followed by a multibody $D$ decay, such as $D \to K_S π^-π^+$, $D \to K_S K^-K^+$ and $D \to K_S π^-π^+π^0$. The main advantages of the method is that it uses only Cabibbo allowed $D$ decays, and that large strong phases are expected due to the presence of resonances. Since no knowledge about the resonance structure is needed, $γ$ can be extracted without any hadronic uncertainty.

hep-ph↗

arXiv2003

Measuring $γ$ in $B^\pm \to K^\pm (K K^*)_D$ decays

We develop a method to measure the CKM angle $γ$ without hadronic uncertainties from the analysis of $B^\pm \to K^\pm D^0$ and $K^\pm \D0bar$ followed by singly Cabibbo-suppressed $D$ decays to non CP-eigenstates, such as $K^\pm K^{*\mp}$. This method utilizes the interference between $b\to c\bar u s$ and $b\to u\bar c s$ decays, and we point out several attractive features of it. All the modes that need to be measured for this method are accessible in the present data.

hep-ph↗

arXiv2002

Measuring the Weak Phase gamma in Color Allowed B->DKpi Decays

We present a method to measure the weak phase gamma in the three-body decay of charged B mesons to the final states D K pi0. These decays are mediated by interfering amplitudes which are color-allowed and hence relatively large. As a result, large CP violation effects that could be observed with high statistical significance are possible. In addition, the three-body decay helps resolve discrete ambiguities that are usually present in measurements of the weak phase. The experimental implications of conducting these measurements with three-body decays are discussed, and the sensitivity of the method is evaluated using a simulation.

hep-ph↗

arXiv2002

What can we learn from a measurement of sin(2 beta + gamma)?

The constraints on the value of the CKM phase gamma that may be achieved by prospective measurements of sin(2 beta) and sin(2 beta + gamma) are discussed. Significant constraints require quite small errors, and may depend on assumptions about strong phases. The measurement of sin(2 beta + gamma) combined with other experiments could provide valuable limits on new physics in Bd-Bdbar mixing.

hep-ph↗

arXiv1999

Impact of D0-D0bar mixing on the experimental determination of gamma

Several methods have been devised to measure the weak phase gamma using decays of the type B+- --> D K+-, where it is assumed that there is no mixing in the D0-D0bar system. However, when using these methods to uncover new physics, one must entertain the real possibility that the measurements are affected by new physics effects in the D0-D0bar system. We show that even values of x_D and/or y_D around 10^{-2} can have a significant impact in the measurement of sin^2{gamma}. We discuss the errors incurred in neglecting this effect, how the effect can be checked, and how to include it in the analysis.

hep-ph↗

arXiv1999

Discrete Ambiguities in the Measurement of the Weak Phase Gamma

Several time-independent methods have been devised for measuring the phase gamma of the Cabibbo-Kobayashi-Maskawa unitarity triangle. It is shown that such measurements generally suffer from discrete ambiguity which is at least 8-fold, not 4-fold as commonly stated. This has serious experimental implications, which are explored in methods involving B->DK decays. The measurement sensitivity and new physics discovery potential are estimated using a full Monte Carlo detector simulation with realistic background estimates.

hep-ph↗