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R-QCD Programme at BESIII Guangshun Huang University of Science and Technology of China (USTC) BESIII R-QCD Workshop Aug.16, 2016, Liaoning Normal U., Dalian Outline BESIII R-QCD overview; Precision measurement of R value; Versatile QCD studies; Summary Aug.16, 2016, Dalian G.S. Huang: R-QCD 2 Physics in BESIII -QCD group mass measurement; Measurement of R value in 24.6 GeV; Study of high mass charmonia in 3.84.6 GeV; QCD studies: – – – – – – – 2016.7.11, Lu An Measurement of form factors; Fragmentation function; Cross section of exclusive processes; Baryon pair production near threshold; Initial state radiation; Phase between electromagnetic and strong interaction; …… G.S. Huang: 973 tau-QCD 3 R-QCD at BESIII • Part of the tau-QCD group, one of the five physics groups at BESIII; • Major fundings (USTC-IHEP): Key project of NSFC: BEPCII/BESIII重粲结构精细扫描和QCD实验研究; 973 project of MOST: 北京谱仪III tau-粲物理实验研究:与QCD物理研究 (also include tau physics). Aug.16, 2016, Dalian G.S. Huang: R-QCD 4 Major plans for data taking 6% Charm baryons 3.5% Y(2175)? Babar • Phase I: pre-study, 8 days (2012) to extend? ❶ Machine study at 2.0, 2.5 and 4.2(4.6) GeV, MC tuning, … • Phase II: scan continuum region, 4 months (2015) ❸ 15 points in 2.03.6 GeV, step 100 MeV, 100k+ hadrons<3 GeV. •Phase III: scan resonance region, 1.5 months (2013-2014) ❷ 100 points in 3.84.6 GeV, 100k events, step 2, 5,10, 20 MeV. Single/separated beam for beam associated background study. Aug.16, 2016, Dalian G.S. Huang: R-QCD 5 Scan data for R-QCD studies • 800 pb-1 in 2.0 – 3.671 GeV; • For proton, neutron, hyperons, and mesons. 7 Apr. 2016, Mainz G.S. Huang: Timelike Form factors @BESIII 6 R Scan in 3.8 - 4.6 GeV • Data taken 2013.12.9 - 2014.1.24; • 104 energy points in total, 800 pb-1; • >100k hadronic events each points. Nov.12, 2014, CERN 7 Data sets for R-QCD Studies 2012 test run: 4 points at low energies; 2013-2014 scan: 104 points >3.8GeV, 800 pb-1; 2014-2015 scan: 20 points in 2-3 GeV, 525 pb-1. + data at continuum from various projects; + (3770), XYZ data (for ISR studies). For more practical information, please visit, http://docbes3.ihep.ac.cn/~tauqcdgroup/ R-QCD Group meeting: 3 PM Wednesday. Aug.16, 2016, Dalian G.S. Huang: R-QCD 8 Work distributions Discussed between QCD and LH groups 2015.1.28 • R measurement: USTC + IHEP + JGU • Baryon form factors – – – – – ppbar: Xiaorong, Lei, Cristina, Dexu, Christoph, Alaa, Yadi nnbar: Paul, Alaa, Xiaorong, Samer, Yadi Lambda form factor: Cui, Karin Lambda Sigmabar0: Cui, Joachim, Karin Sigma Sigmabar: Cui, Walter, Karin All baryon pairs: Qinglei(LH) • Baryon threshold studies – – – – Lambda-pair: Xiaorong, Liang Lambda Sigmabar0: Xiaorong Sigma Sigmabar: Liang, Xin Xi Xibar: Lei, Zhen • Baryon excited states Aug.16, 2016, Dalian G.S. Huang: R-QCD 9 Work distributions Discussed between QCD and LH groups 2015.1.28 • Y(2175) related – – – – – – – – – phi pi+ pi-: Zhihong; Fang Liu(LH) phi pi0 pi0: Yateng; Xiaolin Kang(LH) New decays: Huanhuan Liu(LH) h1 pi pi: h1(KKpi0) eta: Peilian Li rho eta: Zhe, Magnus phi eta: Xinlei, Magnus (pi+ pi-) recoil: Xinlei, Xiaorong (pi0 pi0) recoil: Yateng • Multi-hadron – – – – ee -> 4pi (pi0): Haiming ee -> K K pi pi (pi0): Inclusive hadron: Xinlei, Zhe, Benedikt, Andreas; Peilian Liu(LH) Momentum distribution: • Beyond Standard Model – ee -> eta_c: Joachim, Andrzej Aug.16, 2016, Dalian G.S. Huang: R-QCD 10 e- Definition of R: • At lowest order s + e e- Rº q- hadrons lowest order q m- s e+ • At higher order = SQf2 flavor color m+ Number of quark colors • R is one of the most fundamental quantities in particle physics that directly reflect the flavor and color of quarks. • Directly test quark model & QCD, and discover new particles. Aug.16, 2016, Dalian G.S. Huang: R-QCD 11 Measurement of R Values R 1 N had N bg s m m L had (1 ) Our goal: 3% precision Nhad: observed hadronic events Nbg: background events L: integrated luminosity had: detection efficiency for Nhad : radiative correction factor smm: can be precisely calculated(QED). Measurement of R is to measure the total s(e+e-→hadrons) Except for controlling each item to the precision requested, stable long term machine and detector performance is crucial. Aug.16, 2016, Dalian G.S. Huang: R-QCD 12 Our expectation from the test run • Publications: – – – – Proton form factor, drafting Lambda threshold, in review Inclusive hadron production, ongoing R value, still long way to go? • R measurement: – – – – LundARLW tuning; New generator (Ronggang); Hadronic event selection; Luminosity determination. All have to be finished! • The time windows is 10 months! Aug.16, 2016, Dalian G.S. Huang: R-QCD 13 Our expectation from the test run • Publications: – – – – – Proton form factor, published Lambda threshold, preliminary Luminosity determination, draft Inclusive hadron production, presented R value in continuum, presented • More works: – LundARLW tuning; – Pythia? – Hadronic event selection. • We have to release the R values as soon as possible! Aug.16, 2016, Dalian G.S. Huang: R-QCD 14 Status: analyses with test run data • Publications: – – – – – – Proton form factor, published in 2015 (LundARLW + Exclusives) tuning, submitted to CPC Lambda threshold, CWR since May 12 Luminosity determination, with Spokes Mar.21, May 4 Inclusive hadron production, still ongoing R value in continuum, with conveners since Apr.8 • More works: – LundARLW tuning, stalled for long, restarting – Pythia? No plan – Cross check using Phokhara, with JGU group • I have to say our efficiency is too, too low! Aug.16, 2016, Dalian G.S. Huang: R-QCD 15 R values in the continuum region Based on 2012 test run + other continuum data. Aug.16, 2016, Dalian G.S. Huang: R-QCD 16 R Scan in 3.8 - 4.6 GeV • Data taken 2013.12.9 - 2014.1.24; • 104 energy points in total; • >100k hadronic events each points. Aug.16, 2016, Dalian G.S. Huang: R-QCD 17 QCD studies at threshold, Xiaorong Zhou, CWR for 3 months cc near threshold, Weiping Wang, with referees e+e-K+K-, by Dong Liu, with referees J/ resonance parameters, by Xingyu Zhou, with conveners e+e-/0, , by Zhe Zeng, memo almost ready e+e-p𝑝, by Lei Xia, memo almost ready e+e-K+K-, by Zhihong WangYankun Sun, finalizing memo Inclusive 0/Ks, e+e-, by Xinlei Gao, ongoing Energy calibration for R scan, by Dong Liu, ongoing e+e-+-, by Zhihong Wang Yaxing Tan, restarting e+e-00, by Yateng Zhang, no progress e+e-n𝑛, by Xiaorong Zhou, no progress Aug.16, 2016, Dalian G.S. Huang: R-QCD 18 Summary • Data for R-QCD studies has been there for us to explore; • Our visibility was very good around 2015 data taking, but then diminished; • Quite a few analyses ongoing, but overall the progresses are very slow; • The situation must be improved! • 形势严峻、压力巨大! Aug.16, 2016, Dalian G.S. Huang: R-QCD 19