## Belle and Belle II

Belle is an international experiment at the Japanese laboratory for particle physics KEK, which has been collecting data from 1999 to 2010. In this period 771 million electron positron collisions have been recorded, which lead to the production of a B meson pair. These particles and their decays provide deep insights into the physics of the microcosm. In particular, we looked into differences between particles and anti-particles, the so-called CP violation. Belle's results have confirmed the predictions of Makoto Kobayashi and Toshihide Maskawa made in 1973, thus laying the experimental ground for the Nobelprize in physics awarded to these two researchers in 2008.

The Vienna group has built the readout electronics of the Belle silicon strip tracker (SVD). Our physics research, co-funded by the Austrian science fund, focuses on the determination of the Cabibbo-Kobayashi-Maskawa matrix elements $|V_{cb}|$ and $|V_{ub}|$, charm meson physics and $B_s$ meson decays.

Now Belle is being upgraded to become Belle II. From 2018 the new experiment will accumulate data 40-times as fast as Belle. Vienna assumes responsibility for the overall design and construction of the silicon strip detector, and has developed the origami module concept. We also make significant contributions to the track reconstruction software and to the development of the physics case for Belle II.

Please direct all inquiries to: Christoph Schwanda

## Group members

• ### Christoph Schwanda

Deputy director

PostDoc

Technician

PhD Student
• ### David Hergesell

Diploma Student

## Selected publications

### Measurement of the decay $B\to D\ell\nu_\ell$ in fully reconstructed events and determination of the Cabibbo-Kobayashi-Maskawa matrix element $|V_{cb}|$

R. Glattauer, C. Schwanda et al. (Belle Collaboration)
Phys. Rev. D 93, 032006 (2016) ,  13-10-15

### The Physics of the $B$ Factories

A.J. Bevan, B. Golob, Th. Mannel, S. Prell, B.D. Yabsley, Kazuo Abe, H. Aihara, F. Anulli, N. Arnaud, T. Aushev, M. Beneke, J. Beringer, F. Bianchi, I.I. Bigi, M. Bona, N. Brambilla, J. Brodzicka, P. Chang, M.J. Charles, C.H. Cheng, H.
Eur.Phys.J. C74 (2014) 3026 ,  19-11-14

### Inclusive semileptonic fits, heavy quark masses, and $V_{cb}$

Paolo Gambino, Christoph Schwanda
Phys.Rev. D89 (2014) 014022 ,  24-01-14

### Measurement of the decays $B^0_s\to J/\psi\phi(1020)$, $B^0_s\to J/\psi f_2′(1525)$ and $B^0_s\to J/\psi K^+K^-$ at Belle

F. Thorne, C. Schwanda et al. (Belle Collaboration)
Phys.Rev. D88 (2013) 114006 ,  02-12-13

### Measurement of the form factors of the decay $B^0\to D^{*-}\ell^+\nu$ and determination of the CKM matrix element $|V_{cb}|$

Wolfgang Dungel, Christoph Schwanda et al. (Belle Collaboration)
Phys. Rev. D82, 112007 (2010) ,  30-12-10