Tau – Charm Summaryfah/bestalks/us-prc-tau...Tau mass measurement Novosibirsk performing a new tau...
Transcript of Tau – Charm Summaryfah/bestalks/us-prc-tau...Tau mass measurement Novosibirsk performing a new tau...
TauTau –– Charm SummaryCharm Summary
Frederick A. HarrisFrederick A. HarrisJune. 16, 2006June. 16, 2006
Workshop on US/PRC
Cooperation in HEP
Workshop – Tau CharmThere were many very and very useful presentations. I will not try to summarize all of them. Many thanks to all the authors.I will only make some general comments.
BEPCII/BESIIIStatus: Approved and under construction;
commissioning 2007.
There has been tremendous progress. See overview
talk by Li Weiguo and other more detailed talks.
Design luminosity = 1 x 1033 cm-2 s-1
Changing face of BESIII
•BEPCII linac installation complete(new electron gun; new position source; new rf power (klystrons and modulators); and others.Most design specifications reached at 1st test run.
Linac
Two thirds of storage ring magnets have been installed
BESIII Detector
Be beam pipe
SC magnetMuon Counter
Drift Chamber
CsI(Tl) calorimeter
TOF
Detector
Detector
Resonance Energy(GeV) Peak Lum.(1033cm-2s-1)
Physics Cross Section (nb)
Nevents/yr
J/ψ 3.097 0.6 3400 10 × 109
τ 3.670 1.0 2.4 12 × 106
DsDs 4.030 0.6 0.32 1.0 × 106
ψ(2S) 3.686 1.0 640 3.2 × 109
D0D0bar 3.770 1.0 3.6 18 × 106
D+D- 3.770 1.0 2.8 14 × 106
DsDs 4.140 0.6 0.67 2.0 × 106
Average Lum: L = 0.5×Peak Lum.; data taking time: T = 107s/year
Nevent/year = σexp ×L× T
Year Event Production
Huge J/ψ and ψ(2S) samples at BESIIIDesign luminosity = 1 x 1033 cm-2 s-1
Physics: Importance of tau – charm regionTremendous variety: taus at threshold, R, charm,
charmonium, transition region between perturbative and
non-perturbative QCD, etc.
Many new particles: X, Y, Z, etc. Hybrids? Glueballs?ψ(3770) charm threshold
Still much interest in this physics.Good turn out at Charm06, held June 5-7.
64 registered participants, more than 100 attendees.47 from abroad and 20 from United States. about 50 talks given.
Much also being done at B factories and elsewhere.
EXAMPLES:
Tau – charm physics
Radiative ψ decay is the ideal glueball hunting ground!
From Jim Napolitano
But CLEOc will not produce enough events to study
quantum correlations.
BESIII UpgradesParticle ID. Need R&D on improved PID for pi/K separation. Important for D D-barmixing. See:
Alan Schwartz “Particle upgrade plans for Super Belle”.Yeukun Heng “PID upgrade of BESIII”.
Need beam energy measurement.
1.0 T1.0 T magnet
----9 layersμ counter
RichσT(ps) = 100-110/layer Double layer
TOF
2.0%0.3 cm /√E
Δ E/√E(0/0) = 2.5 %(1 GeV)σz(cm) = 0.5cm/√E
EMC
6%σdE/dx (0/0) = 6 - 7 %
0.5 %ΔP/P (0/0) = 0.5 %(1 GeV) MDC
90 μmσXY (μm) = 130
CLEOcBES IIIDetector
BESIII and CLEOc comparison
Tau mass measurementNovosibirsk performing a new
tau mass measurement. (see “tau and psi mass measurement at KEDR”, talk at “e+ e- collisions from phi to psi”, Feb. 28 – Mar. 2, Novosibirsk, Russia)
• Resonant depolarization
• Previously measured J/ψ and ψ(2S) masses.
• Very preliminary result:
225.018.017.021.0 MeV/c96.1776 ++
−−=τm
245.035.0 0.10MeV/c 77.1776 ±= +
−τm
BES
Goal δ(m) = 0.15 to 0.20 MeV/c2
This will be an important measurement for
BESIII. Must reduce systematic error.
13 June 2006
Beam Energy Calibration
Workshop on Future PRC/US Cooperation in High Energy Physics
Alex Bondar
Absolute Beam Energy Calibration at Novosibirsk
Alex Bondar, Budker Institute of Nuclear Physics,Novosibirsk, Russia
Motivation:
Precise mass measurement of the
τ-lepton
D0,D+,Ds -mesons
13 June 2006
Beam Energy Calibration
Workshop on Future PRC/US Cooperation in High Energy Physics
Alex Bondar
13 June 2006
Beam Energy Calibration
Workshop on Future PRC/US Cooperation in High Energy Physics
Alex Bondar
13 June 2006
Beam Energy Calibration
Workshop on Future PRC/US Cooperation in High Energy Physics
Alex Bondar
KEDR Collab. , depolarization method:Single energy scale at level of 0.8 keV, or 10 –4 MeVTotal systematic error at level of 9 keV, or 10 – 3 MeV
Absolute calibration of energy scale
Fix, stable, regular, eliminate and controllable
UNSTABLE and IRREGULAR,uncontrollable
BESI: δE=0.2MeV
Bottleneck
Mo Xiaohu Slides
Statistical and systematic uncertainties have been studied based on BESI performance experience.
Monte Carlo simulation and sampling technique are adopted to obtain optimal data taking point for high accurate τ mass measurement. We found:
optimal position is located at large derivative of cross section near threshold ;
one point is enough, and 45 pb–1 is sufficient for accuracy up to 0.1 MeV .Many factors have been taken into account to
estimate possible systematic uncertainties, the total relative error is at the level of 1.3 ×10 – 5. However the absolute calibration of energy scale may be a key issue for further improvement of accuracy of τmass.
Summary
Thanks!
Other Topics to prepare for:(Besides R, tau, charm, and charmonium)
ISR Physics – Nice talk from Genia Solodov.2 gamma physics
Physics: Yellow Book
• Write a yellow book on BESIII physics: a summary of theoretical and experimental tau-charm physics and the BESIII physics reach.
http://bes.ihep.ac.cn/bes3/phy_book/book/book.html
• Organized by Li Haibo.• Contributors include D. Asner and
I. Bigi.• Questions to answer:
– Physics opportunities relative to other experiments?
– Priorities?– Time Scale?
• Charm2006: Workshop on Tau-Charm Physics• June 5 – 7, 2006, Beijing, China
Workshop• Proposed by TD to encourage collaboration with
US.• Many CLEOc people attended CHARM06 and left!• Met with them during Charm06 and started
dialogue. Other interested parties attendedthis workshop.
• Workshop a success in beginning discussions between interested groups and BES.
• But need a further meeting with BES, interested groups, and DOE and NSF.
• Workshop a great success. Many thanks to Fred Gilman and Chen Hesheng for organizing the workshop,to DOE, NSF, and CAS for sponsoring it, and to IHEP for hosting it.
Thanks