# International Workshop on e⁺e⁻ collisions from Phi to Psi 2017

Europe/Berlin
Schloss Waldthausen

#### Schloss Waldthausen

Im Wald 1<br /> 55257 Budenheim
Description

Bild-Urheber: Niels Paul Bethe - MESA Animation; Gestaltung: artefont

The 11th edition of the "International workshop on e+e- collisions from Phi to Psi" (PhiPsi17) is organized by the Institute for Nuclear Physics of the Johannes Gutenberg University of Mainz and will be held at Schloss Waldthausen, an early 20th century mansion located in the forests at the north-western Mainz city limits, on June 26-29, 2017.

PhiPsi17 is the continuation of the biennial workshop series, started in Karlsruhe (1996) and in Novosibirsk (1999). The aim is to bring together experimentalists and theorists to review in detail the status of hadron physics at low energy accelerators, share new developments, and discuss the potential of existing and future facilities.

The proceedings of the PhiPsi17 workshop are published in EPJ Web of Conferences Vol. 218.

The workshop will be followed by the XIXth meeting of the Working Group on Radiative Corrections and Monte Carlo Generators for Low Energies (RadioMonteCarLOW), held on June 30th. The aim of this Working Group is to bring together theorists and experimentalists in order to discuss the current status of radiative corrections and Monte Carlo generators at low energies.

Participants
• Achim Denig
• Alaa Dbeyssi
• Alberto Lusiani
• Alessandra Filippi
• Alex Keshavarzi
• Alexander Botov
• Alexandr Milstein
• Alexey Nefediev
• Andre de Gouvea
• Andreas Nyffeler
• Andrej Arbuzov
• Andrey Sukharev
• Andrzej Kupsc
• Antoine Gérardin
• B. Lee Roberts
• Bastian Kubis
• Boris Shwartz
• Brice Garillon
• Carl Carlson
• Carlo Carloni Calame
• Changzheng Yuan
• Christoph Florian Redmer
• Christoph Hanhart
• Christoph Lehner
• Christopher Thomas
• Cristina Collicott
• Cristina Morales
• Daniel Molnar
• Denis Epifanov
• Dexu Lin
• Dmitry Shwartz
• Dmitry Zhuridov
• Dominik Schollmayer
• Dong Liu
• Egle Tomasi-Gustafsson
• Elena Perez del Rio
• Emilie Passemar
• Emmanuella Gyan-foriwaa
• Ernst Schilling
• Eugene Chudakov
• Evgeny Solodov
• Farinaldo Queiroz
• Fedor Ignatov
• Frank Maas
• Franziska Hagelstein
• Fred Jegerlehner
• Gilberto Colangelo
• Graziano Venanzoni
• Guangshun Huang
• Harald Merkel
• Hartmut Wittig
• Henryk Czyz
• Hideyuki Nakazawa
• Hubert Spiesberger
• Igal Jaegle
• Igor Danilkin
• Islam Shalaby
• Ivan Logashenko
• Johann Kuehn
• Judith Plenter
• Julian Müller
• Julian Rausch
• Kenneth Antwi
• Korneliy Todyshev
• Kurt Aulenbacher
• Lars Schmitt
• Lena Heijkenskjöld
• Leonid Kardapoltsev
• Long Bai
• Luciano Maiani
• Malwin Niehus
• Marc Vanderhaeghen
• Marcin Berlowski
• Marco Battaglieri
• Marco Maggiora
• Marek Karliner
• Martin Ripka
• Massimo Passera
• Matthew Needham
• Matthias Neubert
• Matthias Steinhauser
• Max Lellmann
• Maxim Pospelov
• Michael Kohl
• Miha Mihovilovic
• Mirco Christmann
• Nikolay Kivel
• Nserdin Ragab
• Oleksandr Tomalak
• Oleksii Gryniuk
• Olga Shekhovtsova
• Paolo Gauzzi
• Patrick Achenbach
• Patrycja Kisza
• Pepe Guelker
• Randolf Pohl
• Rinaldo Baldini-Ferroli
• Robert Szafron
• Roman Mizuk
• Rong-Gang Ping
• Sabato Stefano Caiazza
• Saliou Dia
• Sascha Wagner
• Silke Grieser
• Simon Eidelman
• Stefanie Dietz
• Stephan Marcus Aulenbacher
• Stephan Paul
• Susanne Fischer
• Szymon Tracz
• Tatyana Dimova
• Tatyana Kharlamova
• Thomas Lenz
• Thomas Teubner
• Thomas Walcher
• Tim-Philip Sixel
• Torben Rathmann
• Tsutomu Mibe
• Wenbiao Yan
• Wolfgang Kluge
• Xiaoshen Kang
• Xiaoyan Shen
• Xingyu Zhou
• Yuping Guo
• Zhentian Sun
• Zhiqing Liu
• Zhiqing Zhang
• Monday, 26 June
• 08:45 09:00
Welcome 15m
Speaker: JGU President Prof. Krausch
• 09:00 09:25
(g-2)µ Overview 25m
Speaker: Thomas Teubner
• 09:25 09:45
(g-2)µ HLBL Overview 20m
Speaker: Andreas Nyffeler (Institute for Nuclear Physics, JGU Mainz)
• 09:45 10:10
FNAL (g-2)µ Experiment 25m
Speaker: B. Lee Roberts
• 10:10 10:35
JPARC (g-2)µ Experiment 25m
Speaker: Tsutomu Mibe
• 10:35 11:00
CMD-3 Overview 25m
Speaker: Ivan Logashenko
• 11:00 11:30
Coffee break 30m
• 11:30 11:55
SND Overview Hadronic Cross Section Measurements 25m
Speaker: Tatyana Dimova (Budker Institute of Nuclear Physics/Novosibirsk State University)
• 11:55 12:20
BABAR Overview Hadronic Cross Section Measurements 25m
Speaker: Konrad Griessinger (University of Mainz)
• 12:20 12:40
BESIII ISR Measurements 20m
Speaker: Martin Ripka (JGU KPH)
• 12:40 13:00
Measurement of the running of α_em at KLOE 20m
Speaker: Graziano Venanzoni
• 13:00 14:30
Lunch 1h 30m
• 14:30 14:50
HVP Determination Orsay group 20m
Speaker: Zhiqing Zhang
• 14:50 15:10
HVP Determination Jegerlehner group 20m
Speaker: Fred Jegerlehner (Humboldt University Berlin/ DESY Zeuthen)
• 15:10 15:30
4 loop QED Calculation of (g-2)µ 20m
Speaker: Matthias Steinhauser
• 15:30 15:50
Spacelike Measurement of HVP contribution to (g-2)µ 20m
• 15:50 16:10
The theory of e+e- → non-vector states 20m
Speaker: Johann Kuehn
• 16:10 16:40
Coffee break 30m
• 16:40 17:00
CMD-3 measurement of e+e- → π+π- 20m
Speaker: Fedor Ignatov (Budker Institute of Nuclear Physics)
• 17:00 17:20
Speaker: Korneliy Todyshev (BINP)
• 17:20 17:40
Speaker: Wenbiao Yan
• 17:40 18:00
Perspectives for Hadronic Cross Section Measurements at BELLE-II 20m
Speaker: Boris Shwartz
• 18:00 18:20
SND measurement of e+e- → π0 γ 20m
Speaker: Leonid Kardapoltsev (Novosibirsk State University, Budker Institute of Nuclear Physics)
• 19:00 20:00
Reception 1h Schlosshalle

### Schlosshalle

• Tuesday, 27 June
• 08:45 09:05
The Phokhara and Ekhara event generators 20m
Speaker: Henryk Czyz (Inst. of Physics, Univ. of Silesia)
• 09:05 09:25
The BABAYAGA event generator 20m
Speaker: Carlo Carloni Calame
• 09:25 09:45
Event generators for Multi Hadronic Production in e+e- 20m
Speaker: Rong-Gang Ping
• 09:45 10:05
Radiative corrections to elastic electron proton scattering and the uncertainty in the proton charge radius 20m
Speaker: Andrej Arbuzov (Joint Institute for Nuclear Research)
• 10:05 10:25
ISR measurement of electromagnetic form factors of the proton at low Q² 20m
Speaker: Miha Mihovilovic (JGU Mainz)
• 10:25 10:55
Coffee break 30m
• 10:55 11:20
Tau theory overview 25m
Speaker: Emilie Passemar (Indiana University/JLab)
• 11:20 11:45
Tau studies - Experimental overview 25m
Speaker: Denis Epifanov
• 11:45 12:05
Status and progress of the HFLAV-Tau group activities 20m
Speaker: Alberto Lusiani (Scuola Normale Superiore and INFN sezione di Pisa)
• 12:05 12:30
Review Dark Forces 25m
Speaker: Maxim Pospelov
• 12:30 12:50
Dark Photon studies at BABAR 20m
Speaker: Alessandra Filippi (INFN Torino)
• 12:50 14:00
Lunch 1h 10m
• 14:00 14:20
The Dark Photon studies at BELLE 20m
Speaker: Igal Jaegle
• 14:20 14:40
The BDX experiment 20m
Speaker: Marco Battaglieri
• 14:40 15:05
Review lepton flavor violation 25m
Speaker: Andre de Gouvea
• 15:05 15:25
Precision QED systems 20m
Speaker: Robert Szafron
• 16:30 18:00
MAMI Tour 1h 30m Institut für Kernphysik

#### Institut für Kernphysik

• 18:30 20:00
Poster Session Helmholtz-Institut Mainz

#### Helmholtz-Institut Mainz

Staudingerweg 18, 55128 Mainz
• 18:30
A Cylindrical GEM Inner Tracker for the BESIII Experiment at IHEP 1h 30m
The Beijing Electron Spectrometer III (BESIII) is a multi-purpose detector collecting data provided by the collisions in the Beijing Electron Positron Collider II (BEPCII), hosted at the Institute of High Energy Physics of Beijing. BESIII has already collected the world's largest sample of $J/\psi$ and $\psi(2s)$. Due to the unprecedented luminosity of the BEPCII, the most inner part of the Multilayer Drift Chamber (MDC) is showing aging effects. A new Inner Tracker is being built, based on the new technology of Cylindrical Gas Electron Multipliers (CGEM). The CGEM-IT project is deploying several new features and innovations with respect to the other state-of-art GEM detector: the $\mu$-TPC and analog readout, exploiting both time and charge measurements, allow to reach a 130 µm spatial resolution in the 1 Tesla magnetic field of the BESIII experimental scenario; the support of anodes and cathodes is now composed of Rohacell, a PMI foam with a very low impact on material budget; a new “jagged” design of the anode allows for the reduction of the inter-strip capacitance. The poster provides an update on the status of the project, with a particular focus on the experimental data collected by planar and cylindrical prototypes with cosmic rays and test beams data. These results are beyond the state of the art for GEM technology in such an intense magnetic field. The CGEM-IT project has been founded by the European Commission in the action H2020-RISE-MSCA-2014.
Speaker: Marco Maggiora (INFN Torino)
• 18:30
Accessing the real part of the amplitudes of the forward scatterings of J/$\psi$ and $\phi$ mesons on the protons from photoproduction at threshold 1h 30m
We provide an updated analysis of the forward J/$\psi$-p scattering amplitude, relating its imaginary part to $\gamma p \to J/\psi p$ and $\gamma p \to c\bar{c}$ cross sections data, and calculating its real part through a once-subtracted dispersion relation. From a global fit to both differential and total cross section data, we extract a value for the spin-averaged J/$\psi$-p s-wave scattering length $a_{\psi p} = 0.046 \pm 0.005$ fm, which can be translated into a J/$\psi$ binding energy in nuclear matter $B_\psi = 2.7 \pm 0.3$ MeV. We estimate the forward-backward asymmetry to the $\gamma p \to e^- e^+$ process around the J/$\psi$ resonance, which results from interchanging the leptons in the interference between the J/$\psi$ production and the Bethe-Heitler mechanisms. To a good approximation this asymmetry depends linearly on $a_{\psi p}$, and can reach values around -25 % for forthcoming J/$\psi$ threshold production experiments at JLab. Its measurement can thus provide a very sensitive observable for a refined extraction of $a_{\psi p}$. We also made a preliminary analysis of the case of $\phi$-p forward scattering. A lack of inclusive cross section data, as well as the absence of a consistent dataset for the exclusive total and differential cross section of the $\phi$ photoproduction off the proton, does not allow us to draw precise constraints on the fit parameters at this point. By fixing the value of Regge slope, for both elastic and inelastic total $\phi$-p scattering cross sections, $\alpha_{el} = \alpha_{inel} = 1.092$ taken from fits of total photoproduction off the proton, we estimate the value of the subtraction constant of the forward elastic amplitude $T_{\phi p}(0) \approx 46.3$, which is approximately two times higher than what we obtained for the J/$\psi$ case. The estimated forward-backward asymmetry was shown to reach values of about -20% for the beam energies $E = 2.2, 4.4$ GeV. The suitable kinematics were investigated for the specific setup of HMS and SHMS detectors of Hall C at JLab. Studies for the other JLab experiments (e.g. GlueX, SOLID) are ongoing.
Speaker: Mr Oleksii Gryniuk (JGU Mainz)
• 18:30
An Improved Limit for $\Gamma_{ee}$ of X(3872) and $\Gamma_{ee}$ Measurement of $\psi(3686)$ 20m
Using the data sets taken at center-of-mass energies above 4 GeV by the BESIII detector at the BEPCII storage ring, we search for the reaction $e^+e^-\to\gamma_{\mathrm{ISR}} X(3872)\to\gamma_{\mathrm{ISR}}\pi^+\pi^-J/\psi$ via the Initial State Radiation technique. The production of a resonance with quantum numbers $J^{PC}=1^{++}$ such as the $X(3872)$ via single photon $e^+e^-$ annihilation is forbidden, but is allowed by a next-to-leading order box diagram. We do not observe a significant signal of $X(3872)$, and therefore give an upper limit for the electronic width times the branching fraction $\Gamma_{ee}^{X(3872)}\mathcal{B}(X(3872)\to\pi^+\pi^-J/\psi)<0.13$ eV at the 90% confidence level. This measurement improves upon existing limits by a factor of 46. Using the same final state, we also measure the electronic width of the $\psi(3686)$ to be $\Gamma_{ee}^{\psi(3686)}=2213\pm 18_\mathrm{stat}\pm 99_\mathrm{sys}$ eV.
Speaker: Mr Martin Ripka (JGU KPH)
• 18:30
Beam Dump Experiment (BDX) @ MESA 20m
At the Institute for Nuclear Physics in Mainz the new electron accelerator MESA will go into operation within the next years. In the extracted beam operation (155 MeV, 150 uA) the P2 experiment will measure the weak mixing angle in electron-proton scattering with a very high precision. For the desired accuracy 10,000 hours of operation time are needed and therefore the high-power beam dump of this experiment is ideally suited for a parasitic dark sector experiment. This poster outlines the physical motivation for a Beam Dump Experiment @ MESA that can significantly contribute to DM searches. At MESA there will be a limited but dedicated floor space available for the BDX. On this basis, first ideas, calculations and drawings for such an experiment are shown.
Speakers: Mr Mirco Christmann (KPH) , Dr Patrick Achenbach (Mainz University)
• 18:30
Composite Baryogenesis 20m
The composite models, which address the existing problems of the Standard Model, generally include the excited leptons. I introduce new scenarios for possible generation of the baryon asymmetry of the universe using these new particles. The scenarios do not contradict to the small neutrino masses and the proton stability, and can be tested at the LHC.
Speaker: Dr Dmitry Zhuridov (University of Silesia)
• 18:30
Dark Photon Search at BESIII with ISR Method 20m
Using a data set of 2.93 fb$^{−1}$ taken at a center-of-mass energy of 3.773 GeV with the BESIII detector at the BEPCII collider, a search for an extra U(1) gauge boson, also denoted as a dark photon, has been performed. We examine the initial state radiation reactions $e^{+}e^{-}\to e^{+}e^{−}\gamma_{ISR}$ and $e^{+}e^{-}\to\mu^{+}\mu^{−}\gamma_{ISR}$ for this search, where the dark photon would appear as an enhancement in the invariant mass distribution of the leptonic pairs. We observe no obvious enhancement in the mass range between 1.5 and 3.4 GeV/$c^{2}$ and set a 90% confidence level upper limit on the mixing strength of the dark photon and the Standard Model photon. We obtain a competitive limit in the tested mass range.
Speaker: Dr Yuping Guo (KPH, JGU Mainz)
• 18:30
Decay of eta' into four pions and its impact on the doubly-virtual eta' transition form factor 20m
It has been shown that the decay amplitude $\eta'\rightarrow \pi^+\pi^-\gamma$ has an important impact on the dispersion-theoretical analysis of the singly-virtual $\eta'$ transition form factor [1]. Consequently, we expect that the *doubly*-virtual transition form factor can be understood in more detail, starting from an analysis of the decay $\eta'\rightarrow2(\pi^+\pi^-)$. It was found that the $\eta'$ decay into four charged pions is clearly dominated by $\rho$ resonances [2]. The thus predicted branching ratio has recently been confirmed by a measurement of the BESIII collaboration [3]. The $a_2$ tensor meson corrects the amplitude of $\eta' \rightarrow \pi^+\pi^-\gamma$ noticeably [4] and should therefore also be incorporated into the decay at hand. We use a resonance model to describe the tree-level contribution of the $a_2$ to the decay $\eta' \rightarrow 2(\pi^+\pi^-)$ and amend the resulting amplitude through a dispersive analysis of the universal $\pi\pi$ final-state interactions. This leads to non-factorizing contributions to the doubly-virtual $\eta'$ transition form factor needed for the light-by-light scattering contribution to the anomalous magnetic moment of the muon and will allow to judge the validity of the factorization ansatz currently used therein. References: - [1] C. Hanhart *et al.* (2013), arXiv:1307.5654 [hep-ph] - [2] F. K. Guo, B. Kubis and A. Wirzba (2011), arXiv:1111.5949 [hep-ph] - [3] M. Ablikim *et al.* [BESIII Collaboration] (2014), arXiv:1404.0096 [hep-ex] - [4] B. Kubis and J. Plenter (2015), arXiv:1504.02588 [hep-ph]
Speaker: Ms Judith Plenter (Helmholtz-Institut für Strahlen- und Kernphysik, Bonn-Cologne Graduate School of Physics and Astronomy)
• 18:30
Description of tensor meson transition form factors at large $Q^2$ within QCD factorization approach 20m
Due to multiple possible polarizations hard exclusive production of tensor mesons by virtual photons or in heavy meson decays offers interesting possibilities to study the helicity structure of the underlying short-distance process. Motivated by the first measurement of the transition form factor $\gamma^*\gamma \to f_2(1270)$ at large momentum transfers by the BELLE collaboration we present an improved QCD analysis of this reaction in the framework of collinear factorization including contributions of twist-three quark-antiquark-gluon operators and an estimate of soft end-point corrections using light-cone sum rules. The results appear to be in a reasonable agreement with the data, in particular the predicted scaling behavior is reproduced in all cases.
Speaker: Nikoilay Kivel (HIM)
• 18:30
Development of large scale focal plane detectors for MAGIX 20m
**MAGIX** is a planned experiment that will be implemented at the upcoming accelerator MESA in Mainz. Due to its location in the energy-recovering lane of the accelerator beam-currents up to **1 mA** with a maximum energy of **105 MeV** will be provided for precision experiments. MAGIX itself consists of a jet-target and two magnet-spectrometers. Inside the spectrometers **GEM**-based detectors will be used in the focal plane. The design goals for the detector modules are a spatial resolution of **50 μm**, a size of **1,20 x 0,30 m²** and a minimal material budget. To accomplish these goals we started developing several GEM-prototypes to study different behaviors and techniques for the final detector. The GEMs used are provided by CERN and are trained, stretched and framed in our laboratory. In this contribution the requirements, ongoing development and achieved measurements are presented.
Speaker: Mr Pepe Guelker (KPH - JGU Mainz)
• 18:30
Development of the internal Gas-Jet-Target for MAGIX 20m
MAGIX is a planned experiment that will be implemented at the upcoming accelerator MESA in Mainz. Due to its location in the energy-recovering lane of the accelerator beam currents up to 1 mA with a maximum energy of 105 MeV will be provided for precision experiments. MAGIX itself consists of a Jet Target and two magnet-spectrometers. The Jet-Target consists of a Laval-Nozzle and a catcher which is mounted in a high performance pumping system. This contribution is about the hydrodynamics and the technical implementation of the target system.
Speaker: Stephan Marcus Aulenbacher (JGU Mainz)
• 18:30
Dispersive reconstruction of the neutral pion transition form factor obeying asymptotic constraints 20m
The neutral pion transition form factor plays prominent roles both in the hadronic light-by-light scattering corrections to the muon anomaly and in the electromagnetic rare decays of the pion. The singly-virtual transition form factor has been investigated in dispersion relations [1], where the form factor in time-like region was predicted based on the $e^+e^-\to 3 \pi$ cross section data and the high-precision space-like form factor was obtained at low energy by analytic continuation. In this work, we generalize the dispersive analysis into the doubly-virtual kinematics, incorporating the celebrated upshots obtained from perturbative quantum chromodynamics [2-6]. The resulting form factor provides a possibility to study the $\pi^0$-pole contribution to the hadronic light-by-light scattering of the muon $g-2$ in a model independent manner with well estimated uncertainty. [1] M. Hoferichter, B. Kubis, S. Leupold, F. Niecknig and S. P. Schneider, *Dispersive analysis of the pion transition form factor*, Eur. Phys. J. C **74** (2014) 3180, [arXiv:1410.4691 [hep-ph]]. [2] G. P. Lepage and S. J. Brodsky, *Exclusive Processes in Quantum Chromodynamics: Evolution Equations for Hadronic Wave Functions and the Form-Factors of Mesons*, Phys. Lett. B **87** (1979) 359. [3] G. P. Lepage and S. J. Brodsky, *Exclusive Processes in Perturbative Quantum Chromodynamics*, Phys. Rev. D **22** (1980) 2157. [4] S. J. Brodsky and G. P. Lepage, *Large Angle Two Photon Exclusive Channels in Quantum Chromodynamics*, Phys. Rev. D **24** (1981) 1808. [5] V. A. Nesterenko and A. V. Radyushkin, *Comparison of the QCD Sum Rule Approach and Perturbative QCD Analysis for $\gamma^\ast \gamma^\ast \to \pi^0$ Process*, Sov. J. Nucl. Phys. **38** (1983) 284. [6] V. A. Novikov, M. A. Shifman, A. I. Vainshtein, M. B. Voloshin and V. I. Zakharov, *Use and Misuse of QCD Sum Rules, Factorization and Related Topics*, Nucl. Phys. B **237** (1984) 525.
Speaker: Long Bai (Bonn University)
• 18:30
High-precision measurement of the proton radius with an active hydrogen Time Projection Chamber 20m
One of today’s most pressing question in nuclear physics is the understanding of the so-called "proton radius puzzle". The puzzle originates from a striking discrepancy between the electric charge radius of the proton, extracted from the muonic hydrogen Lamb shift, compared to measurements based on electron-proton scattering experiments and atomic transition measurements in electronic hydrogen. Solving this problem requires experiments approaching the problem in new ways. To address this puzzle, we will perform a high- precision measurement of the differential ep-scattering cross section in the region of low momentum transfer at the Mainz Microtron (MAMI). To perform this experiment, a new-generation detector, consisting of a Hydrogen Time Projection Chamber (TPC) and Forward Tracking System will be constructed, and a new electron beam line at MAMI will be built. The experimental setup will allow us to measure the energy and angle of the recoil proton with unprecedented accuracy as well as the angle of the forward scattered electron. This is a completely new approach compared to other experiments, which mainly focus on the electron angle. A test measurement with a TPC prototype will be conducted at MAMI in August 2017, which will serve as basis for the main experiment.
Speakers: Dr Patrik Adlarson (Johannes Gutenberg Universität-Mainz) , Dr Vahe Sokhoyan (Johannes Gutenberg Universität-Mainz)
• 18:30
Lattice calculation of the pion transition form factor 20m
We report on the lattice QCD calculation of the π0→γ∗γ∗ form factor with photon virtualities in the range Q2∈[0−1.5]~GeV2. Different lattice spacings and pion masses are used to extrapolate our result to the physical point. First, we check that our results, once extrapolated to the chiral and continuum limit, are compatible with the chiral anomaly. Then, the shape of the form factor is compared to different phenomenological models proposed in the literature and to experimental data in the single-virtual case when one photon is on-shell. From a phenomenological point of view, this form factor determines the π0 pole contribution to hadronic light-by-light (HLbL) scattering in the muon g−2,thought to be dominant.
Speaker: Dr Antoine Gerardin (Institute for Nuclear Physics, University of Mainz)
• 18:30
Magix: A versatile experiment for low-energy physics 20m
Running in parallel to the existing MAMI electron accelerator, the new workhorse of the Institute of Nuclear Physics of the University of Mainz is an energy recovering electron recirculator capable of delivering 1 mA polarized currents at 105 MeV to a fix target experiment in its path. The Magix experiment is currently being developed to exploit that power to perform high-precision experiments in that energy range. This poster will present part of the ambitious physics program of that experiment including, among others, the search for new particles like the possible new dark mediators in both the visible and invisible decay channels and the precision spectroscopy below the hadronization threshold to improve the constraints on the electronic radius of the proton and to test the prediction of modern effective field theories.
Speaker: Mr Sabato Stefano Caiazza (KPH Institut, JGU Universitaet Mainz)
• 18:30
Measurement of $\Gamma_{ee} * B_{hadrons}$ for J/$\psi$ meson with KEDR detector 20m
We report a new precise measurement J/$\psi$ meson leptonic width performed with the KEDR detector at the VEPP-4M $e^+e^-$ collider. Cross sections for the processes $e^+e^-\to hadrons$ and $e^+e^- \to e^+e^-$ were measured at J/$\psi$ resonance energy range and $\Gamma_{ee}*B_{hadrons}$(J/$\psi$) value was obtained with accuracy about 2%. Leptonic and total widths were calculated, using the table values of the leptonic branching ratios.
Speaker: Mrs Tatyana Kharlamova (BINP)
• 18:30
Measurement of $\Gamma_{ee} \times \mathcal{B}_{\mu\mu }$ for $\psi(2s)$ meson with KEDR detector 20m
Based on the nine data sets taken with the KEDR detector since 2004 in charmonia region, we report $\Gamma_{ee} \times \mathcal{B}_{\mu\mu} = 19.4 \pm 0.3 \pm 0.4$ eV for $\psi(2s)$ meson. The total luminosity accounted for is more than 6.5 pb$^{-1}$, corresponding to about $4 \times 10^6 \psi(2s)$. There were several scans of the resonance allowing us to know the collider energy spread and several runs where the data was taken at the $\psi(2s)$ peak and slightly below it. The Particle Data Group does not mention any direct measurement of this quantity yet. Instead, many $\psi(2s)$ parameters, including partial widths and branching ratios, are obtained using a complicated simultaneous fit of results of various experiments.
Speaker: Mr Andrey Sukharev (BINP)
• 18:30
Measurement of $e^+ e^- \rightarrow K^+ K^-$ cross section at $E_{cm} = 2.0 - 3.08$ GeV 20m
The cross section of the $e^+e^-\to K^+K^-$ process is measured with data samples collected with Beijing Spectrometer (BESIII) at $\sqrt{s} = 2.00 - 3.08$ GeV. The results are consistent with those of BaBar and with better precision. A structure near $2.2$ GeV is observed with mass $2229.8 \pm 5.3_{stat} \pm 17.2_{syst}$ MeV and width $143.7 \pm 12.0_{stat} \pm 7.8_{syst}$ MeV. The kaon form factor is extracted from $\sigma(e^+e^-\to K^+K^-)$ and compared with theoretical prediction.
Speaker: Mr Dong Liu (USTC)
• 18:30
Measurement of J/$\psi$ Decay Widths with an Energy Scan Method 20m
We measure the cross sections of $e^+e^- \to e^+e^-$ and $e^+e^- \to \mu^+\mu^-$ processes using the data set collected with the BESIII detector at fifteen energy points around the $J/\psi$ resonance. By fitting the theoretical cross section curves of the two processes as functions of energy to the measured cross section data simultaneously, the combinations of $J/\psi$ decay widths $\Gamma_{ee}\Gamma_{ee}/\Gamma_{\rm tot}$ and $\Gamma_{ee}\Gamma_{\mu\mu}/\Gamma_{\rm tot}$ are extracted to be ($0.348 \pm 0.008$) keV and ($0.339 \pm 0.005$) keV with a covariance $0.000,037$ keV$^2$. With the fitting results, $\Gamma_{ee}/\Gamma_{\mu\mu}$ is evaluated as $1.025 \pm 0.014$, which proves the lepton universality. Assuming the lepton universality and combining the branching ratio of $J/\psi$ leptonic decay measured by BESIII in 2013, the total width $\Gamma_{\rm tot}$ and the leptonic width $\Gamma_{ll}$ are determined to be ($94.3 \pm 1.9$) keV and ($5.64 \pm 0.10$) keV, respectively.
Speaker: Xingyu Zhou (IHEP Beijing)
• 18:30
Quark mass dependence in photon pion scattering 20m
Usually the simulation of scattering processes in lattice QCD is carried out at unphysical high values of the quark masses [1]. Hence, a method to extrapolate data obtained in lattice calculations to physical masses is needed to allow for comparison between theory and experiment. To obtain a sound extrapolation, dispersion relations and chiral perturbation theory (ChPT) can be invoked. While a simple combined approach known as the inverse amplitude method (IAM) allows for a successful extrapolation of $\pi\pi\rightarrow\pi\pi$ data [2], a more complicated framework is needed for inelastic processes such as $\gamma\pi\rightarrow\pi\pi$. By extending the dispersive description derived in Ref. [3], the extrapolation can be performed for $\gamma\pi\rightarrow\pi\pi$. This particular process is interesting due to both its contribution to the anomalous magnetic moment of the muon and its connection to the axial anomaly. References: - [1] Briceno et al.: https://arxiv.org/abs/1507.06622 - [2] Bolton, Briceno, Wilson: https://arxiv.org/abs/1507.07928 - [3] Hoferichter, Kubis, Sakkas: https://arxiv.org/abs/1210.6793v2
Speaker: Mr Malwin Niehus (Helmholtz Institut für Strahlen- und Kernphysik, Universität Bonn and Bonn-Cologne Graduate School of Physics and Astronomy)
• 18:30
Recent Results of the Hadronic Cross Sections Measurement of the Processes $e^+e^-\to KKn\pi$ with CMD-3 Detector 20m
After the upgrade of the positron injection facility the electron-positron collider VEPP-2000 started to operate at the end of last year and delivers an excellent luminosity, which is higher than the previous in 2-3 times. The detector CMD-3 has gained a new statistic, which corresponds to integrated luminosity of about 30 pb$^{-1}$. Many processes in the energy region from 1 to 2 GeV go through the production of multihadron events with kaons in the final state. The paper presents preliminary results of measurements of the cross sections for some processes.These new results are badly required to improve the unceraincy of calculation of the hadronic contribution to (g-2)/2 of muon particularly in the light of new experiment in FNAL.
Speaker: Prof. Gennady Fedotovich (Budker institute of nuclear physics)
• 18:30
Search for the $\chi_{c1}$ charmonium in direct $e^+e^-$ production 20m
With the high luminosity accelerator -- BEPCII and the BESIII detector located in Beijing, China, for the first time, we are able to search for a non-vector charmoinum -- the $\chi_{c1}$ state in $e^+e^-$ direct production. In order to investigate the full interference line shape of $\chi_{c1}$ with continuum background, we propose to take data with $e^+e^-$ central-of-mass energy 2 MeV below, exactly at, and 2 MeV above the $\chi_{c1}$ nominal mass. From 14th May to 1st June, and 11th June to 13th June, the BESIII detector successfully accumulated 175 $pb^{-1}$ data at 3508.66 MeV, 175 $pb^{-1}$ data at 3510.66 MeV and 38 $pb^{-1}$ data at 3514.6 MeV. Detailed data analysis is ongoing, and the final results will be released soon.
Speaker: Dr Zhiqing Liu (postdoc)
• 18:30
Study of $\tau\rightarrow 3\pi \nu_\tau$ within extended RChT including tensor and scalar resonances 20m
We analyze the contribution from intermediate spin–0 and spin–2 resonances to the $\tau\rightarrow 3\pi \nu_\tau$ decay by means of a chiral invariant Lagrangian incorporating these mesons. In particular, we study the corresponding axial-vector form-factors. The advantage of this procedure with respect to previous analyses is that it incorporates chiral (and isospin) invariance and, hence, the partial conservation of the axial-vector current. This ensures the recovery of the right low-energy limit, described by chiral perturbation theory, and the transversality of the current in the chiral limit at all energies.
Speaker: Dr Olga Shekhovtsova (Institute of Nuclear Physics)
• 18:30
Study of the process $e^+e^- \to\pi^+\pi^-\pi^0\eta$ at the SND detector 20m
The reaction $e^+e^- \to \pi^+\pi^-\pi^0\eta$ has been studied in the experiment with the SND detector at the VEPP-2000 $e^+e^-$ collider. The reaction proceeds via the four intermediate states: $\omega\eta$, $\phi\eta$, $a_0\rho$ and structureless $\pi^+\pi^-\pi^0\eta$ state, which may be, for example, $\rho(1450)\pi$ with $\rho(1450) \to \rho(770)\eta$. The total $e^+e^- \to \pi^+\pi^-\pi^0\eta$ cross section and cross section for the four intermediate states have been measured and fitted in the vector meson dominance model.
Speaker: Mr Alexander Botov (Budker Institute of Nuclear Physics)
• 18:30
Testing $\chi_{c}$ properties at BELLE II 20m
The integrated luminosity in the BELLE II experiment (20-50 ab$^{-1}$) will allow to access information never available before. It was found, within the model implemented in the newly updated Monte Carlo generator EKHARA, that at BELLE II it will be possible to study in detail $\chi_{ci} − \gamma^∗ − \gamma$ form factors through measurements of the reaction $e^+e^- \to e^+e^-\chi_{ci} (\to \gamma J/\psi (\to \mu^+ \mu^-))$. The proposed measurements will also serve as tests of the models predicting the $\chi_{c1}$ and $\chi_{c2}$ electronic widths.
Speaker: Patrycja Kisza (University of Silesia)
• 18:30
The crystal Zero Degree Detectors at BESIII 20m
The BESIII experiment based at the BEPCII $e^{+}e^{-}$ collider (Beijing, China) is investigating physics in the charm-$\tau$ region. Processes in which the particles emission peaks towards small polar angles, such as Initial State Radiations (ISR) from $e^{+}e^{-}$ annhiliations, are currently detected with limited efficiency. In order to improve their detections, we propose two small taggers placed at the very forward/backward angles. Each detector is composed of two arrays of 4x3 rectangular-shaped scintillating LYSO crystals, separated by a gap. The scintillation light will be collected by silicon photomultipliers (SiPMs) and the signals will be digitized using sampling Analog-to-Digital Converters (sADC). In this contribution, we present the results from the tests of a single LYSO crystal and the read-out electronics using radioactive sources. Studies of the final setup, using Geant4 based simulation of BESIII and the cZDDs, are also shown. This work is supported by the DFG under contract No. CRC 1044.
Speaker: Dr Brice Garillon (JGU Mainz)
• 18:30
The Design and Performance of the Münster Gas-Jet Target for MAGIX at MESA 20m
The experiments at the future electron accelerator MESA (Mainz Energy-recovering Superconducting Accelerator) at the University of Mainz focus on the validity of the Standard Model of particle physics. Thereby, the main interest is the search for dark photons as candidates for dark matter, and precision measurements of fundamental constants, such as the proton radius or the electroweak mixing angle. The MAGIX experiment (MESA Gas Internal target eXperiment) will be located in the energy-recovering sector of this future electron accelerator with energies up to 105 MeV, a beam current of 1 mA, and a high luminosity of $10^{35} \frac{1}{\mathrm{cm}^2 \mathrm{s}}$. MAGIX will consist of a multi-purpose spectrometer and a gas-jet target which was designed, built up, and set into operation at the University of Münster. The gas-jet beam is produced by the expansion of gas within Laval nozzles and provides constant thickness in time and space (e.g. $10^{19} \frac{\mathrm{atoms}}{\mathrm{cm}^2}$ directly behind the nozzle). By cooling and changing the pressure of the gas at the nozzle, the gas-jet target can also be operated in a cluster-jet mode. This offers the possibility to achieve a directed, less divergent beam even at large distances from the nozzle. Thereby, the highest thicknesses with a lower gas flow to improve the vacuum conditions can be achieved. Currently, measurements to characterize the target beam depending on different properties, e.g. different nozzle designs, different stagnation conditions of the gas in front of the nozzle, are performed. For this purpose, a Mach-Zehnder interferometer is used to determine the thickness distribution and the shape of the gas-jet. The design of the Münster gas-jet target and the beam properties will be presented and discussed.
Speaker: Mrs Silke Grieser (WWU Münster)
• 18:30
The MUon Scattering Experiment (MUSE) at PSI 20m
The proton is not an elementary particle but has a substructure governed by the interaction of quarks and gluons. The size of the proton is manifest in the spatial distributions of the electric charge and magnetization, which determine the response to electromagnetic interaction. Recently, contradictory measurements of the proton charge radius between muonic hydrogen and electronic probes have constituted the proton radius puzzle, which has been challenging our basic understanding of the proton. The MUon Scattering Experiment (MUSE) in preparation at the Paul-Scherrer Institute (PSI) has the potential to resolve the puzzle by measuring the proton charge radius with electron and muon scattering simultaneously and with high precision, including any possible difference between the two, and with both beam charges. The status of the MUSE experiment will be reported. This work has been supported by the U.S. National Science Foundation and Department of Energy.
Speaker: Prof. Michael Kohl (Hampton University)
• 18:30
The OLYMPUS Experiment at DESY 20m
Hard two-photon exchange has been favored theoretically to explain the previously observed discrepancy in measurements of the elastic proton electric-to-magnetic form factor ratio with polarized and unpolarized methods. Several experiments have been carried out to investigate the effects of two-photon exchange. The OLYMPUS experiment at DESY has been one of three dedicated experiments to use comparisons of positron-proton and electron-proton scattering to unequivocally determine the effects of two-photon exchange. Results from the OLYMPUS experiment will be presented. This work has been supported by the U.S. National Science Foundation and Department of Energy.
Speaker: Prof. Michael Kohl (Hampton University)
• 18:30
Theoretical Description of the Invariant Mass Distribution of the decay $Y(4260) \to J/ \psi \; \pi^{+} \pi^{-}$ 20m
In this work, we aim to provide a physical description of the recent BESIII data on the exotic meson decay, $Y(4260) \to J/ \psi \; \pi^{+} \pi^{-}$. In the $\psi \pi$ invariant mass distribution, one can observe two peaks, which correspond to the exotic meson $Z_c(3900)$ and its kinematic reflection. Its shape can be parameterized as a S-wave Breit-Wigner and a background, which comes from the final state interactions of two pions. The latter we implement using unitarity and analyticity constraints. In result, a simultaneous description of $\psi \pi$ and $\pi \pi$ invariant mass distributions is achieved.
Speaker: Mr Daniel Molnar (JGU Mainz)
• 18:30
Two-photon form factors of the pseudoscalar mesons in Phokhara and Ekhara Monte Carlo generators 20m
Phenomenological model, which describe very well the coupling of the $\pi^0, \eta, \eta^{'}$ mesons to two photons is presented. The model of the form factors is consistent with the data in the space-like region, as well with the data in the time-like region with exception of the $\pi^0$ BaBar data and $\eta$ CMD2 data. The obtained form factors are implemented in Monte Carlo event generator Phokhara and Ekhara and investigation of the impact of radiative corrections for a cross section of $e^+ e^- \to \gamma \pi^0, (\eta, \eta^{'} )$ is studied.
Speaker: Szymon Tracz (University of Silesia)
• Wednesday, 28 June
• 08:45 09:10
Review of XYZ theory 25m
Speaker: Luciano Maiani
• 09:10 09:35
Recent results on XYZ physics from BELLE 25m
Speaker: Roman Mizuk
• 09:35 10:00
Recent results on XYZ physics from BESIII 25m
Speaker: Zhentian Sun
• 10:00 10:25
Recent results on hadron spectroscopy at LHC 25m
Speaker: Matthew Needham
• 10:25 10:55
Coffee break 30m
• 10:55 11:15
Theory of hadronic molecules applied to the XYZ states 20m
Speaker: Christoph Hanhart
• 11:15 11:35
Recent issues in heavy quark spectroscopy 20m
Speaker: Marek Karliner
• 11:35 11:55
Meson spectroscopy from lattice calculations 20m
Speaker: Christopher Thomas (University of Cambridge)
• 11:55 12:20
Compass Light Quark Spectroscopy 25m
Speaker: Stephan Paul
• 12:20 12:40
BESIII Light Quark Spectroscopy 20m
Speaker: Xiaoshen Kang
• 12:40 13:00
Dalitz plot analysis of three body charmonium decays at Babar 20m
• 13:00 14:15
Lunch 1h 15m
• 14:15 14:40
Speaker: Carl-Edwin Carlson (College of William and Mary)
• 14:40 15:05
The PSI Crema experiment 25m
Speaker: Randolf Pohl
• 15:05 15:25
BESIII results on timelike baryon form factors 20m
Speaker: Alaa Dbeyssi
• 15:25 15:45
Nucleon form factors at threshold 20m
Speaker: Alexandr Milstein (Budker Institute of Nuclear Physics)
• 16:00 16:00
Departure Tour
• 17:00 18:00
Tour Gutenberg-Museum 1h Gutenberg-Museum

#### Gutenberg-Museum

Guided tour in the Gutenberg-Museum

• 18:00 19:00
City Tour 1h Mainz

#### Mainz

Guided city tour in Mainz

• 20:00 23:00
Conference Dinner 3h Heiliggeist

#### Heiliggeist

Dinner will take place in Heiliggeist

• Thursday, 29 June
• 08:45 09:05
The Muon (g-2)µ Theory Initiative 20m
• 09:05 09:25
Lattice calculations for (g-2)µ Mainz 20m
Speaker: Hartmut Wittig
• 09:25 09:45
Lattice calculations for (g-2)µ BNL 20m
Speaker: Christoph Lehner
• 09:45 10:10
Theory γ γ interactions 25m
Speaker: Igor Danilkin (Johannes Gutenberg-Universität Mainz)
• 10:10 10:30
Dispersive analysis of light-meson transition form factors 20m
Speaker: Bastian Kubis (Bonn University)
• 10:30 11:00
Coffee break 30m
• 11:00 11:20
Two-photon physics results from Belle and perspectives for Belle II 20m
Speaker: Hideyuki Nakazawa
• 11:20 11:40
Recent Results on Meson Decays from A2 20m
Speaker: Patrik Adlarson (Johannes Gutenberg Universität-Mainz)
• 11:40 12:00
Transition form factor measurement KLOE 20m
Speaker: Elena Perez del Rio
• 12:00 12:20
Measurements of meson decays and meson transition form factors at CLAS 20m
• 12:20 12:40
Measurement of transition form factors in two-photon collisions at BESIII 20m
Speaker: Christoph Florian Redmer (Institut für Kernphysik, Johannes Gutenberg-Universität Mainz)
• 12:40 13:00
KLOE eta/eta' physics 20m
Speaker: Marcin Berlowski
• 13:00 14:25
Lunch 1h 25m
• 14:25 14:40
X(3915) as a tensor D*D* molecule 15m
Two-photon decays of a tensor D*D* molecule are studied and the suggested approach is applied to the X(3915) charmoniumlike state under the assumption of the latter being a 2++ molecule - a spin partner of the X(3872). It is argued that the existing experimental data disfavour such an identification of this state. Therefore, it is suggested that either the X(3915) has a different exotic nature or it has to be identified as a scalar.
Speaker: Alexey Nefediev (Moscow Institute of Physics and Technology)
• 14:40 14:55
Heavy-quark spin-symmetry partners of Zb(10610) and Zb(10650) molecules 15m
Heavy-quark spin-symmetry (HQSS) partners of the isovector bottomonium-like states $Z_b(10610)$ and $Z_b(10650)$ are predicted within the molecular picture. Treating both $Z_b$ states as shallow bound states, we solve the system of coupled-channel integral equations for the contact plus one-pion exchange (OPE) potentials to predict the location of the partner states with the quantum numbers $J^{++}$ ($J=0,1,2$). In particular, we predict the existence of a narrow tensor $2^{++}$ state residing a few MeV below $B^*\bar B^*$ threshold. It is emphasised that the tensor part of the OPE potential in combination with HQSS breaking due to the nonvanishing B*-B mass splitting has a significant impact on the location of the partner states.
Speaker: Vadim Baru (Institute for Theoretical Physics, Ruhr-University Bochum)
• 14:55 15:15
HLBL Dispersive theory Mainz 20m
• 15:15 15:35
HLBL Dispersive theory Bern 20m
Speaker: Gilberto Colangelo (University of Bern)
• 15:35 15:55
Overview of the BINP accelerator complex 20m
Speaker: Dmitry Shwartz
• 15:55 16:15
High Intensity e+e- Accelerator - Super Tau Charm Factory 20m
Speaker: Guangshun Huang (University of Science and Technology of China (USTC))
• 16:15 16:45
Coffee break 30m
• 16:45 17:10
Overview MAMI and MESA at Mainz 25m
Speaker: Kurt Aulenbacher (Institut für Kernphysik, Universität Mainz)
• 17:10 17:35
Lab report FAIR 25m
Speaker: Lars Schmitt
• 17:35 18:00
Lab report JLAB 25m
Speaker: Eugene Chudakov
• 18:00 18:25
The BELLE-II experiment 25m
Speaker: Changzheng Yuan