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Физика антипротонов низких энергий и антивещества

Физика антипротонов низких энергий и антивещества. О.Д.Далькаров Физический институт им.П.Н.Лебедева РАН. План доклада. 1.BbarB Thresholds a. Baryon electromagnetic form-factor in the time-like region (theory and experiment) b. e+e- annihilation near NbarN threshold

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Физика антипротонов низких энергий и антивещества

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  1. Физика антипротонов низких энергий и антивещества О.Д.Далькаров Физический институт им.П.Н.Лебедева РАН

  2. План доклада 1.BbarB Thresholds a. Baryon electromagnetic form-factor in the time-like region (theory and experiment) b. e+e- annihilation near NbarN threshold (theory and experiment) 2.Low energy antiprotons as a new probe of nuclear matter (theory and experiment) 3.Ultracould antihydrogen – hydrogen systems (theory and proposals)

  3. Cross-sections and nucleon electromagnetic form-factor • From the Lorenz-invariance and charge conservation: <p2| j (0)|p1 >=u(p2 )[F1 (q2 ) +iF2 (q 2) q ]u(p1 ) It is more convenient to introduce GE = F1 – q2/4m2 F2 ; GM = F1 + F2 Taking into account isotopic spin GP = GS + GV ; Gn = GS - GV In the time-like region (q2 < -4m2 ): d /d(pbarp→e+e-)= 2/8Ek {|GM |2(1+ cos2) – 4m2/q2|GE |2 sin2} Near NbarN threshold ( q2 - 4m2 ) GE (-4m2 ) = GM (-4m2 ) = G and so k/m ( pbarp → e+e- ) = 2/2m2|G |2

  4. Experimental data

  5. Proton time-like FF (low q2 )

  6. Proton electromagnetic form-factor ( q2 < -4m2 ) • G = G0 |  (0) | •  (0) ( ``enhancement factor``) • increasis very fast at small k • G0 corresponds to singularities very far from threshold ( VDM ) • O.D.Dalkarov. JETP Lett. 28(1978)183

  7. Analytical behaviour • (0) = 1/ f (-k) ( f(k) is Yost function ) • For S-wave • f (k) = exp(i(k) /  (k2) , • where  (k) is complex phase shift • Therefore • |  (0)| = exp (-Im(k)) / l(k2)l • At small k:  (k)  at k

  8. Hence • G = G0 exp(-Imatk) / l (k2)l • For small k < 1/ Im at • G = C ( 1 – Imatk + bk2…) • a. Linear behaviour of G at small k • b. Connection with pbarp low energy data: • Imat could be extracted from pbarp atomic data ( width of 3S1protonium state: Im a = - 0.8 fm ) • Electromagnetic nucleon form-factor near the NbarN threshold is strongly influenced by NbarN initial state interaction

  9. Coupled channels model for NbarN – e+e- reaction • Potential matrix has a form • VNbarN (OBEP) Vann VNbarN-e+e- • Vann < > 0 • Ve+e--NbarN 0 e+e- • For S-matrix: S = ( 1 – iK ) ( 1 + iK ) • Since VNbarN-e+e- ~  (r), potential matrix and boundary condition were changed • VNbarN Vann 0 Kij (r=0) = Kij0 • Vann 0 0 0 0 1 • 0 0 0 Kij0 = C0 ki kj 0 0 0 • 1 0 0 • Here C0 = (1/3 /2m) G0 • O.D.Dalkarov, K.V.Protasov. Phys.Lett.B280 (1992) 11 • O.D.Dalkarov and K.V. Protasov. Nucl.Phys.A504 (1989) 845 • NbarN model without cut-off parametrs • O.D.Dalkarov and A.Yu.Voronin. Eur.Phys.J. A25 (2005) 429

  10. theory

  11. YbarY thresholds • barthreshold • Experiment: important P – wave contamination in all of observables ( reaction and differential pbarp → bar cross-sections, polarization ) at low relative momenta of  and bar Theory: coupled channel model Existance of bar nearthreshold quasinuclear states J.Carbonell, O.D.Dalkarov and K.V.Protasov. Phys.Lett.B 306 (1993)407 O.D.Dalkarov, P.A.Khakhulin and A.Yu.Voronin Nucl.Phys.A833 (2010) 104

  12. Electromagnetic formfactor of lambda-hyperonPEP-2, BaBar collaboration

  13. EM formfactor of Lambda-Hyperon

  14. Others thresholds O.D.Dalkarov, P.A.Khahulin and A.Yu.Voronin. Nucl.Phys. A833 (2010) 104 • Possibility to extract Im a from the slope parameter • It`s necessary to measure e+e- (pbarp)→ DbarD cross-sections for the relative momenta k < 200 MeV/c

  15. Im a = - 0.44 fm**3

  16. Quasinuclear vector NbarN state • 1. e+e- - 6pions (DCI, ORSAY) • 2. e+e- - mh total cross-section

  17. Green function for composite two-body system • G(r,r`), where r is relative coordinate • +-----------------------+ • V1 G(r,r`) V2 • M ~ < V2 |G(r,r`)|V1 > • Case of G(0,r) for V = -  /r (E.Schrodinger) • Let`s propose: 1. r = r` =0 • 2. G(r,r`) has a pole corresponded to bound state • → • Using usual representation • G(r,r`) =-  (r) *(r') / ( l bl + E + i) + dk k(r)k*(r') / (k2 /2m-E-i) • where b is the binding energy of two-body composite system e+ e-

  18. Finally • G(0,0) = - l(0)l2 /( lbl + E + i ) + dk l k(0)l2 / (k2/2m – E – i) • ++ - + • -----------*----------------------------------|------------------ • pole continuum • Exact compensation of these two terms is possible • Result: nullification of reaction amplitude due to existance of Green function`s zero • O.D.Dalkarov and V G Ksenzov. Pis`ma v ZhETP. 30 (1979) 74 • Pis`ma v ZhETP. 31 (1980) 425

  19. Realistic coupled channels calculations • NbarN: V(OBEP) → NRD potential • NbarN – n : VNbarNh → exp(-2mr)/r • e+e- -- NbarN: Ve+e- → V0 (r) ~ proton electromagnetic form-factor near NbarN threshold • Resulting amplitude: • M(e+e- - n ) = M th + M bg • Mbg was normalized at s = 4 GeV2 • Varying parameters: • 1. Cut-off radius for 33S1 - state • G = (-1)L+S+T =+1, T = 1 • 2. Relative phase: M = M th + M bg • From the best agreement with experiment: r =0.5fm,  = -  /4 • RESULT: quasinuclear 2 33 S1 - state • J PC = 1 - - , M = 1800 MeV and  = 15 MeV • O.D.Dalkarov and K.V.Protasov. Nucl.Phys.A504(1989)845 • “Qusinuclear model”. O.D.Dalkarov, V.B.Mandelzweig and I.S.Shapiro.Nucl.Phys.B21(1970) 88

  20. KbarK and D*barD* thresholds

  21. Low-energy antiprotons as a newprobe of nuclear reaction mechanism • For the validity of the Glauber approach: • a) rectilinearness of the hadron trajectory in a nucleus (eikonal apprpximation); • b) the possibility to neglect the motion of nucleons in the nucleus during the flight time of the hadron through a nucleus (adiabatic approximation)

  22. In the case of protons beam: the validity or invalidity of conditions a) and b) is made simultaneously. . In the case of antiprotons beam: low-energy pbarN scattering is strongly forward directed, moreover, the slope of the cone increases when energy decreases. The specific feature of pbarN scattering can ensure the validity of condition (a) in the case when there no reason for validity of condition (b) i.e. this gives unique possibility to judge independently on the applicability of the adiabatic approximation.

  23. Condition (b): many effects which are at first glance not connected with each other (e.g., rescattering of intranuclear nucleons and off-mass- shell effects in the hadron-nucleon amplitude ) almost completely cancel each other O.D.Dalkarov, V.M.Kolybasov and V.G.Ksenzov. Nucl.Phys. A397(1983) 498 O.D.Dalkarov and V.G.Ksenzov. Yad.Phys.32(1980) 1439 “Frozen” nucleons Antiproton-nucleus interaction at low energy O.D.Dalkarov and V.A.Karmanov. Nucl.Phys. A478(1988) 635

  24. Glauber approach in the theory of low energy Pbar-nucleus scattering • 1. q-dependence of fpbarp(q) – from experimental angular distributions • 2. nuclear transition densities – from electron scattering data • 3. only one fitting parameter: •  = Re fpbarp(0)/Im fpbarp(0) • O.D.Dalkarov and V.A.Karmanov. Nucl.Phys. A445 (1985) 579; Nucl.Phys. A478 (1988) 635 • Resume: Low energy pbar - nucleus scattering is a new unique tool for penetrating into the nuclear many body problem

  25. ULTRACOLD HYDROGEN-ANTIHYDROGEN SYSTEM LPSC Grenoble France J.Carbonell, K.Protasov Lebedev Physical Institute Moscow O.Dalkarov, A.Yu.Voronin CPT symmetry Novel branch of antiAtomic Physics Crossroad of atomic, nuclear, elementary particle physics CERN Programme for Matter-Antimatter Interaction O.D.Dalkarov, J.Carbonell and A.Yu.Voronin. Antiproton-Hydrogen annihilation at sub-kelvin tenperatures. Phys.Rev. A57(1998)4335

  26. E(HH)=-3-i1.5 meV First Quantum Study of H-H molecule

  27. Gravitational effectAntihydrogen bouncing on a surface Mgz z V(z) Quantum reflection from Casimir-Polder potential and gravitational states

  28. “GBar” Collaboration ( CERN, ILL, FIAN ) • Gravitational states of neutrons • V.V.Nesvizhevsky et. al. Phys.Rev. D75 075006 (2007)

  29. bar(bar) and bar thresholds • bar bar bar DbarD • ------l----------l----------l---------------------------------------l---------------------- • 2.2 2.3 2.4 GeV • Pure isospin states • T = 0 bar + bar • T = 1 bar + bar • pbard→ pS + KbarKn (n = 2-4) • Study of -meson spectrum ( 2m - 2m = 150 MeV ) • Exotic states ( bar, T = 2, Q = 2 ) • pbard→ pS + + + K+K---

  30. Baryon-Antibaryon Physics • Laboratoire de Physique Corpusculaire, Blaise Pascal Universite Dr. H.Fornvieille Lebedev Physical Institute O.D.Dalkarov, V.A.Karmanov Preparation of new experiments (electromagnetic baryon form factor in the time-like region, baryon-antibaryon and charmonium states,…) FAIR (Facility for Antiproton and Ion Reseach, Darmstadt, Germany) PANDA Collaboration

  31. СПАСИБО ЗА ВНИМАНИЕ

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