Scattering length expansion of the coupled channels $$\bar pp \to \bar \Lambda \Lambda$$ and $$\bar \Lambda \Lambda \to \bar \Lambda \Lambda$$ near the? production threshold

Schneider-Neureither, AG; Pirner, H. J.; Kerbikov, B. O.; Mahalanabis, J.

doi:10.1007/bf01303026

Cited by 7 publications

(4 citation statements)

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“…transition have been studied in many theoretical papers [34]{ [61]. These descriptions have been of three general types: the strangeness production originates from the t-channel exchange of K mesons [34]{ [40]; the process originates from the s-channel annihilation of a uu pair and the subsequent production of an ss pair that is accompanied by four`spectator' quarks [41]{ [51] (other work has focused on quark descriptions via quark counting rules [52]); model-independent analyses of the low-momentum data, which are based on a partial-wave amplitude decomposition [53]{ [55]. Since only a few partial waves contribute here, it may be possible to learn more about the underlying reaction mechanism.…”

Section: Introductionmentioning

confidence: 99%

Observables in high-statistics measurements of the reactionp¯p→Λ¯Λ

Barnes¹,

Diebold²,

Franklin³

et al. 1996

Phys. Rev. C

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Associated strangeness production was studied in the pp ! ! p + p reaction at the CERN antiproton facility LEAR using the experimental setup of PS185. Results from two high{statistics measurements at incident a n tiproton momenta of 1:642 and 1.918 GeV/c are reported. Approximately 40 000 reconstructed events at each momentum have allowed us to measure the total and dierential cross-sections, the spin polarizations, the spin correlations, and the singlet fractions of the pair. Since the decays of both the and the w ere simultaneously observed in the same detector, we are able to provide upper limits on CP and CPT violation phenomena in the weak interaction.

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Section: Introductionmentioning

confidence: 99%

Observables in high-statistics measurements of the reactionp¯p→Λ¯Λ

Barnes¹,

Diebold²,

Franklin³

et al. 1996

Phys. Rev. C

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“…It is further convenient t o expand the denominator We now have t o correct for the initial-state interaction. The S-matrix elements of the pp scattering that enter formula (4) are parametrized [15,16] in the { L S J ) basis, where L and S refer to the orbital momentum and total spin in the p p system. To implement the initial-state interaction one has therefore to make the transformation of the partial-wave helicity amplitudes into { L S J ) ones, which can be done easily: the cross section.'…”

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confidence: 99%

NN¯annihilation at the open charm threshold

Kerbikov

Kharzeev

1995

Phys. Rev. D

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We discuss the pp annihilation into a pair of charmed D mesons not far from the threshold of the reaction. An interesting interference pattern in the differential cross section is predicted to arise from the existence of both t-channel charmed-baryon exchange and s-channel qii charmonium resonance amplitudes. We argue that the experimental study of this process would provide new and valuable information about the unknown ppP" and A , N D couplings. These are important to know to solve the long-standing puzzle of the heavy flavor content of baryons and to test the semilocal duality. PACS number(s): 13.85.Ni, 14.20.Lq, 14.40.LbThere exist many meson states which couple to the NN system. These states then appear as the poles in the amplitudes of the NN interaction and this, in principle, can lead to observable effects. However, the common situation in the light quark sector is that the widths of the resonances are large; they therefore overlap and interfere. The necessity to account, in addition, for a n interference with the (generally unknown) t-channel exchange amplitudes further complicates the situation, making a clean and detailed analysis an extremely difficult task.In this sense a rather uncommon situation is encountered in the pp annihilation into a pair of D mesons close to the threshold. The s-channel resonance here is the k1'(3770) charmonium state with a relatively small width of I? ~2 3 . 6 MeV. The nearest charmonia are too far and narrow to cause any appreciable interference effects, so the pole corresponding to 9" can, to a good accuracy, be considered as isolated. In addition, there exist of course nonresonant t-channel amplitudes, corresponding to the exchange of the states with the quantum numbers of charmed baryon(s). The relation between the strengths of the resonant and nonresonant amplitudes depends on two couplings, N N~I I and N,ND. Almost nothing is known at present about the values of the corresponding coupling constants, apart from a few rather controversial predictions 11-51. A possible admixture of the light-quark-antiquark pairs in the wave function of the 9'' can further complicate the situation, giving rise to a nonperturbative contribution to the pp + k" amplitude. Another interesting issue concerning the N,ND coupling is that the knowledge of its value is desirable to solve the problem of the intrinsic heavy flavor content of the baryons [6,7]. The arguments listed above indicate that the study of the pp + DD reaction is interesting, but at the same time leave seemingly little chance to 'On leave of absence from Moscow State University, Moscow, Russia. make a reliable prediction for the relative importance of s-and t-channel exchange amplitudes.There exists, however, an attractive theoretical scheme which, when applied to our situation, gives a definite answer-the (semilocal) duality 18-1 11. Namely, the senlilocal duality implies that the averages (over a finiteenergy segment) of cross sections corresponding to the sum of all possible amplitudes in s and t channels, respectively,...

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“…As for the theoretical predictions, there are essentially two classes of models [61][62][63][64][65][66] which are schematically represented in Fig. 2 (see also [67] The models give similar results, illustrating once more that both hadron and quark basis might be used to describe low-energy physics. The choice is a matter of convenience, but one should avoid double counting when trying to combine the two pictures.…”

Section: Strangeness-exchange Reactionsmentioning

confidence: 92%

“…As for the theoretical predictions, there are essentially two classes of models [61][62][63][64][65][66] which are schematically represented in Fig. 2 (see also [67]): a) nuclear-physics type of models, where the transition is described in terms of K, K * , . .…”

Section: Strangeness-exchange Reactionsmentioning

confidence: 99%

Antiproton induced reactions

Richard

1994

Czech J Phys

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The various aspects of antiproton physics are shortly reviewed, and its relevance for the possible discovery of new particles and effects is pointed out. Then a survey of the nucleon-antinucleon interactions is given. In the nucleon-antinucleon annihilations, there is a big amount of experimental data that call for theoretical explanation. Importance of specific spin and isospin channels for our understanding of antiproton physics is stressed.

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Scattering length expansion of the coupled channels $$\bar pp \to \bar \Lambda \Lambda$$ and $$\bar \Lambda \Lambda \to \bar \Lambda \Lambda$$ near the? production threshold

Abstract: We fit the scattering lengths in the triplet s-, pand d-waves for the two channels ~p--~flA and flA--~AA near the A production threshold to the differential cross da section )-~ (fip--,.#A) and to the polarization P.

Cited by 7 publications

References 20 publications

Observables in high-statistics measurements of the reactionp¯p→Λ¯Λ

Observables in high-statistics measurements of the reactionp¯p→Λ¯Λ

NN¯annihilation at the open charm threshold

Antiproton induced reactions

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