Tau – Charm Summaryfah/bestalks/us-prc-tau...Tau mass measurement Novosibirsk performing a new tau mass measurement. (see “tau and psi mass measurement at KEDR”, talk at “e+

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