talk0502

Using - and -K atoms for the experimental check of low-energy QCD L. Nemenov (CERN, Switzerland): 

Using - and -K atoms for the experimental check of low-energy QCD L. Nemenov (CERN, Switzerland) Presented by L. Tauscher Basel University, Switzerland

Why atoms ?: 

Why atoms ? Particles scatter off each other in well defined atomic quantum states Very low Q’s  atomic level scheme sensitive to scattering length Strong interaction leads to complex energy eigenvalues Enl - i Gnl/2 = EnlQED + enl - i Gnl/2 Example: pp e1S  2a0 + a2 G1S  |a0 - a2|2 “Model-independent” determination of scattering lengths

Experimental status on pp: 

Experimental status on pp K++-e+ve (Ke4)  phase difference d00(s)-d11(s) for 4mp2<s<mK2 a0 = 0.26 ± 0.05[mp-1] Roy eq. Rosselet et al. CERN 1977 a0 = 0.203 ± 0.033[mp-1] Roy eq. Pislak et al. BNL / E865 a2 = -0.055 ± 0.023[mp-1] 2001/2003 a0 = 0.216 ± 0.013stat ± 0.004syst ± 0.002th [mp-1] Roy eq a2 = from ChPT DIRAC (A2p) after analysis of ALL collected data so far s|a0-a2|  ± 5%stat (± 3%syst ± 2%th)estimated  ± 0.013stat (± 0.008syst ± 0.005th)estimated

Theory pp : 

Theory pp a0 = 0.220 ± 0.005 [mp-1] (2.3%) a2 = -0.0444 ± 0.0010[mp-1] (2.3%) a0- a2 = 0.265 ± 0.004 [mp-1] (1.5%)

Theory pK : 

Theory pK

Experimental status on pK: 

Experimental status on pK In the 60’s and 70’s set of experiments were performed to measure πK scattering amplitudes. Most of them were done studying the scattering of kaons on protons or neutrons, and later also on deuterons. The kaon beams used in these experiments had energies ranging from 2 to 13 GeV. The main idea of those experiments was to determine the contribution of the One Pion Exchange (OPE) mechanism. This allows to obtain the πK scattering amplitude. Analysis of experiments gave the phases of πK-scattering in the region of 0.7 ≤ m(πK) ≤ 2.5 GeV. The most reliable data on the phases belong to the region 1 ≤ m(πK) ≤ 2.5 GeV.

Theoretical accuracy on atomic quantities: 

Theoretical accuracy on atomic quantities

Theoretical accuracy on atomic quantities: 

Theoretical accuracy on atomic quantities

Principle of lifetime measurement: 

Principle of lifetime measurement

Pbr to lifetime conversion: 

Pbr to lifetime conversion

DIRAC II (Addendum): 

DIRAC II (Addendum)

DIRAC II Set-up: 

DIRAC II Set-up

DIRAC II Set-up: 

DIRAC II Set-up Decrease the systematic errors. Single–multilayer targets Identification of e±,  ±, K ± and p Increasing of statistics and efficiency of the setup Shielding K ≈ 1.9 Formation of time structure of the spill with the trigger of setup Microdrift chambers New electronics for SFD Increase in the aperture on VH hodoscope and PSH Total K ≈ 4

Metastables: 

Metastables

Metastables: 

Metastables

Metastables: 

Metastables

Metastables: 

Metastables

Metastables: 

Metastables

Metastables: 

Metastables

Metastables: 

Metastables

Metastables: 

Metastables

Metastables: 

Metastables

Prospects beyond DIRAC II: 

Prospects beyond DIRAC II Measure at machines with higher proton current Higher duty factor Higher energy

Yields of atoms as a function of the proton beam momentum: 

Yields of atoms as a function of the proton beam momentum

Slide25: 

*) Precision of Pbr=f(t) can be increased to better then 0.6% private communication by D.Trautmann

Slide26: 

*) Precision of Pbr=f(t) can be increased to better then 0.6% private communication by D.Trautmann

Conclusions: 

Conclusions