# World average values for excited $$D_{(s)}$$ mesons (updated August 2017)

People working on this:   Tara Nanut, Marko Petric

## Mass and width averages

An average mass and width is calculated wherever possible. The calculation of the averages assumes no correlation between individual measurements. The masses and widths of narrow ($$\Gamma<50$$ MeV) orbitally excited $$D$$ mesons, both neutral and charged, are well-established. Measurements of broad states ($$\Gamma\sim$$ 200–400 MeV) are less abundant, as identifying the signal is more challenging.

[Click on plots for high resolution .pdf files]

Tables of measured masses and widths, and our world averages, are here: $$D_s$$ mesons, $$D$$ mesons.

## Branching fraction averages

Detailed tables of measurements of branching fractions for: $$D_s$$ mesons, $$D$$ mesons. It is notable that the branching fractions for $$B$$ mesons decaying to a narrow $$D^{\ast\ast}$$ state and a pion are similar for charged and neutral $$B$$ initial states, while the branching fractions to a broad $$D^{\ast\ast}$$ state and $$\pi^+$$ are much larger for $$B^+$$ than for $$B^0$$.

## Mass differences

A summary of mass difference measurements is listed here.

## Helicity parameter

A summary of helicity parameter measurements is listed here. In $$D^{\ast\ast}$$ meson decays to $$D^{\ast\ast} \to D^{\ast}\pi$$, $$D^{\ast} \to D \pi$$, the helicity distribution is dependent on the helicity parameter, which is sensitive to possible S-wave contributions in the decay.

This page is maintained by Tara Nanut and A. Schwartz and was last updated