1. Hadron mass modifications at J-PARC K. Ozawa (KEK) Contents: Physics motivations On-going experiment at J-PARC Future plans including far future plans Summary

2. Physics Motivation 2016/03/04K. Ozawa2 Mass [GeV] Pseudo scalar meson as a NG boson （ J p =0 - ） Obtain constituent qua ｒ k mass Hadron Mass as excitation levels of “vacuum” In light quarks (u, d, s) sector, hadron mass consists of Bare mass (Higgs) and Dynamical mass (QCD). Dynamical mass part is strongly related to a surrounded medium and chiral symmetry restoration of the medium Reliable experimental information in a (QCD) medium is important. Vector mesons ( , ,  meson) are used as probes. – Mass spectra of vector mesons can connect to qq condensates e.g. Hatsuda and Lee, PRC 46 (1992) R34 – Use leptonic (electron) decays to avoid the final state interaction

3. Measurements at KEK-PS. 2016/03/043 R. Muto et al., PRL 98(2007) 042581 Indication of mass modification! Cu  <1.25 (Slow) e + e - invariant mass Decays inside nucleus Decays outside nucleus  meson has mass modification Modification is shown as an Excess  meson has NO mass modification Blue line shows expected line shape including all experimental effects wo mass modification Invariant mass spectra of electron-positron pairs in  meson mass region. K. Ozawa

4. How do we extract medium information? 2016/03/04K. Ozawa4 We can link vector meson spectra and quark condensates using a QCD sum rule. (Hatsuda and Lee, PRC 46 (1992) R34) (This part is base on discussions by P. Gubler and K. Ohtani) Two point correlation function after the Borel transformation: Spectral Function QCD sum rule for  meson channel: Strangeness content of the nucleon Note: Strangeness contents in nucleus is evaluated as a linear density approximation

5. contents of the nucleon 2016/03/04K. Ozawa5 Taken from M. Gong et al. (χQCD Collaboration), arXiv:1304.1194 [hep-ph]. m s = 75MeV ~ 135MeV is assumed in T. Hatsuda and S.H. Lee

6. Recent Evaluation 2016/03/04K. Ozawa6 P. Gubler and K. Ohtani, Phys. Rev. D 90, 094002 (2014). E325 results 0.96

7. Theory and experiment comparison 2016/03/04K. Ozawa7  sN = 105(41)(37) MeV (Budapest-Marseille-Wuppertal collaboration, arXiv:1510.08013, 2015. Oct. 28)  sN = 32.3(4.7)(4.9) MeV (  QCD collaboration,arXiv:1511.09089, 2015. Nov. 29) However, there are two different Lattice results recently. P. Gubler and K. Ohtani, Phys. Rev. D 90, 094002 (2014). New experimental results are important.

8. J-PARC E16 experiment 2016/03/048 Pb Proton A clear mass spectra in nucleus needs to be identified E325 results K. Ozawa New spectrometer

9. Spectrometer Requirements Coping with a high intensity beam – 10 10 protons per spill, spill length 6s, spill on 2s – Counting rate: 5 kHz/mm 2 (maximum) – We choose a GEM tracker Covering a large area – 5 times larger pair acceptance – 2 times larger coverage in vertical – Large coverage in electron ID counters – Horizontal: +-15 ~ +-135, Vertical: +- 45 Precise mass (momentum) resolution –  Bdl ~ 1Tm – Minimum material to avoid Multiple Scatterings – Position resolution of 100  m Detector configuration – Trackers are placed near target – Electron ID counters are placed in outer side. Total rejection factor of 1000 for two stages identification counters (HBD and LG) 2016/03/04K. Ozawa9 Conceptual Design

10. Design 2016/03/04K. Ozawa10 Target Pb, Cu, C, CH 0.5% radiation length Inside He Chamber GEM Trackers 10cm x 10cm at r=20cm 20cm x 20cm at r=40cm 30cm x 30cm at r=60cm Divided into 3 layers in vertical Readout: APV chip (RD51) Hadron Blind Detector CsI coated GEM 1 segment 60cm x 60cm 30cm x 30cm x 4 Readout: APV chip (RD51) Lead Glass Recycle of TRISTAN (Need modification) Readout: DRS4 based Additional Large Tracking device? Btw HBD and LG Improve resolution and S/N ratio Hadron Identification Detectors? Trigger GEM tracker x HBD x LG DAQ Supported by KEK group Simulation & Analysis Framework 1 st stage: Middle layer (Budget limited) ~ KEK-PS statistics with 1 month run

11. GTR (GEM Tracker) Ionization electrons in the drift gap are collected and amplified by GEMs. Charge collected on to 2D strip readout. – X: 350um pitch Sensitive to bending direction. 100 um resolution required. – Y: 1400um pitch 11 Y1 Y2 X1 X2 X3 GEM readout 3 mm Drift Gap Mesh electrode Trigger 2016/03/04K. Ozawa

12. GTR Performance Center Of Gravity (COG) Method – Ordinal analysis method – ~ 60  m @ 0 degree of incident angle – Worse results for inclined tracks Timing method – Distance in drift field dir. Can be obtained using flight time like mini-TPC – ~ 100  m for all tracks 2D fit (COG + Timing) 12 Residual sigma [um] Incident angle [degree] 01530 100 200 300 Timing method COG method 2D fit 0 Required 2016/03/04K. Ozawa

13. HBD (Hadron Blind Detector) 300x300mm 2 GEM with CsI Based on PHENIX HBD. CF4 serves as radiator and amplification gas Radiator 50 cm. / p.e. ~ 11 Gas Electron Multiplier (GEM) for amplification CsI is evaporated on top GEM – Photocathode (> ~6eV) Trigger 132016/03/04K. Ozawa

14. HBD Pion rejection factor of 100 with 80% electron efficiency achieved at beam test. – Using charge threshold and cluster size. 14 pions electrons Cluster size - 1 Cluster size analysis 2016/03/04K. Ozawa

15. HBD CsI photocathode have to be treated in dry environment. 15 GLOVEBOX prototype HBD chamber (production type) 2016/03/04K. Ozawa

16. FUTURE PLANS 2016/03/04K. Ozawa16

17. Exclusive Measurements Mass spectra of vector mesons in finite temperature or density matter have essential information. However, dynamics of reactions always causes model dependent issues. I proposed a new experiment to measure mass spectra of vector mesons in nucleus with an exclusive condition to minimize such difficulties. 03/Dec/2015K. Ozawa17   A   /  + p+X e+e-e+e-   e+e+ p e-e- Elementary Reaction:  + + n (in A)   + p We can measure  (beam),  (decays), emitted proton (Forward spectrometer) The reaction dynamics can be identified by these measurements.

18.  at rest In addition, when we choose a momentum of the incident beam carefully, we can generate  mesons “at rest”. – Note: Due to a Fermi motion and experimental effects,  mesons still have small momentum. 03/Dec/2015K. Ozawa18 Elementary reaction  + + n (in A)   + p Forward emitted proton carries momentum of incident beam and generated  meson has small momentum We can measure mass spectra in nucleus at “p  0”. The experiment can be done using high-p secondary beam (same as E50)

19. J-PARC HI Project MR RCS HI booster HI LINAC U 35+ 20.0MeV/u U 55+ →U 66+ 19.86→67.0 MeV/u U 86+ 62.34→735.21 MeV/u U 66+ →U 86+ 67.0→62.34 MeV/u U 86+ →U 92+ 735.21→727.0 MeV/u U 92+ 727.0Mev/u→11.15 GeV/u (30GeV@p) stripping U 35+ →U 55+ 20.0→19.86 MeV/u 1903/Dec/2015K. Ozawa Acceleration Scheme for Uranium case(Proposed by H. Harada, J-PARC) New LINAC and Booster for HI must be constructed.

20. J-PARC Heavy Ion specification 20 “Low energy” program (Linac) for unstable nuclei research Ion species – Ne, Ar, Fe, Ni, Kr, Xe,…,U Beam energy – 1 - 10 AMeV (U) Beam current – 10-30 p  A – 10ms, 25Hz 03/Dec/2015 K. Ozawa

21. /0/0 Calculated by JAM model, Y. Nara, Phys. Rev. C61,024901(1999) Physics Study of High Density Matter – Strange meson and baryons – Event-by-event fluctuations – Two particle correlations (YN, YY correlations in high baryon density) – flow (related to EOS?) – Di-leptons (di-electron and di-muon) Vector meson mass spectra Hadron Physics – Hypernuclei – Exotic hadrons  (1405) Dibaryon (H-dibaryon,  N, ,…) Kaonic nucleus (K - pp,…) – Charm J/ , D, charmed baryons 03/Dec/201521 Onset of QGP Search for critical point Properties of Dense matter K. Ozawa 20AGeV case

22. High Intensity Beam for rare probes 03/Dec/2015K. Ozawa22 Charm Dilepton Hypernuclei AGS Ref: HSD calculations in FAIR Baseline Technical Report (Mar 2006) A. Andronic, PLB697 (2011) 203 To collect a significant statistics for rare probes, High intensity beam is required. Beam : 10 10 Hz 0.1% target  Interaction rate 10 7 Hz Centrality trigger 1%  DAQ rate = 100kHz In 1 month experiment:   ee 10 7 -10 9 D,J/  10 5- 10 6 (20AGeV) (10 3 -10 4 (10AGeV)) Hypernuclei 10 5 -10 10

23. Simulated di-electron spectrum (preliminary) 23 Based on  0 spectra of JAM Other hadrons m T -scaled b<1fm (0.25% centrality) Momentum resolution 2% Electron efficiency 50% (No detector response) 10 11 events ⇔ 100k events/s x 1 month running  isolation = rejection efficiency of close opening angle Dalitz pair Calculations by T. Gunji and T. Sakaguchi     03/Dec/2015 Solenoid+Dipole setup K. Ozawa

24. Summary A new Experiment to study in-medium properties of vector mesons is in preparation – We can start the experiment in 2018 Construction of Spectrometer is underway – Developments of GEM Tracker and HBD are almost done – Mass productions of the detectors have been started – Preparation of readout, trigger, DAQ, Computer is on- going Further future plans are also discussed 2016/03/04K. Ozawa24