MESONIC SUPER-ČERENKOV-LIKE EFFECTS IN HADRONIC AND NUCLEAR MEDIA

Transcription

1 MESONIC SUPER-ČERENKOV-LIKE EFFECTS IN HADRONIC AND NUCLEAR MEDIA D.B. ION 1,2), M.L. ION 3) 1) National Institute for Physics and Nuclear Engineering Horia Hulubei, IFIN-HH, Bucharest, P.O. Box MG-6, Magurele, Roania 2) Acadey of Roanian Scientist (A.O.S.R.) 3) Faculty of Physics, Bucharest University, Bucharest, Roania Received March 10, 2010 Generalized esonic Super-Čerenkov Radiations (SČR), as well as their SČRsignatures are investigated. Two general SČR-coherence conditions are found as two natural extrees of the sae spontaneous particles decays in (nuclear or subnuclear) edia. The positions of the pionic SČR-bands in the esonic and baryonic SČRsectors are estiated. The interpretation of the observed (at RHIC) two bup structure of the aziuthal distributions near the away-side jets as experiental evidence for the two SČR-esonic coponents, is suggested. Key words: Pionic Super-Čerenkov radiation, Nuclear pionic Čerenkov-like radiation (NPIČR), SČR-esonic sectors. We recall here that idea that eson production in nuclear interactions ay be described as a process siilar to the Čerenkov radiation has been considered by Wada (1949), Ivanenko (1949) Blohintev and Indenbo (1950), Čzyz, Ericson, Glashow (1959), Srz (1962) and D.B. Ion ( ). For the any detailed results on esonic Čerenkov-like effect see Refs. [1 3,5,9 13] presented in Fig. 1 while for the generalized Super-Čerenkov see Refs. [14 15]. In Ref. [1] fro Fig. 1 D.B. Ion developed a general classical and quantu theory of the esonic Čerenkovlike radiation in hadronic and nuclear edia. Moreover, the vector-esonic Cerenkov-like radiation as well as baryonic Cerenkov-like effects in nuclear and hadronic edia were also introduced for the first tie in Ref. [1 2, Fig. 1]. Then, it was predicted copletely the properties of the esonic Čerenkov-like radiation in the case when the esonic refractive index is given by a single pole approxiation. Then, they obtained a good agreeent with the integrated cross section of the single eson production in the hadronic collisions (see Fig. 9 fro Ref. [1]). In , we have extended [1 7] these ideas to the nuclear edia where the pionic (NPIČR) and gaa Čerenkov radiation (NGČR) should be possible to be eitted fro charged particles oving through nuclei with a velocity larger than the phase velocity of photons or/and pions in the nuclear edia. The refractive indices of the gaa ( n γ ), eson ( n π ), nucleon ( n N ), was calculated by using Foldy-Lax Ro. Journ. Phys., Vol. 55, Nos. 7 8, P , Bucharest, 2010

2 708 D.B. Ion, M.L. Ion 2 Fig. 1 Selected bibliography for introduction in the generalized Super-Čerenkov-like radiations. forula [8] and the experiental pion-nucleon cross sections cobined with the dispersion relations predictions, the refractive index of pions in the nuclear edia have been calculated (see Fig. 2a,b). Then, the detailed predictions for the spontaneous pion eission as nuclear pionic Čerenkov radiation (NPIČR) inside the nuclear ediu are obtained and published in Refs. [3 4]. These ain predictions and conclusions obtained in this way for the low-energy SČR-pionic sector can be suarized as follow (see also Fig. 4): (i) The energy behavior of the pionic refractive index is presented in Fig. 2a; (ii) The true coherent pion eission as nuclear pionic Čerenkov-like radiation (NPIČR) is possible in the following three energy bands (see Fig. 2b): ČB1-NPIČR band for: 190MeV ω 315MeV for all π ±,0 ČB2-NPIČR band for: 910MeV ω 960MeV only forπ +, and ±,0 ČB3-NPIČR band for: 80GeV ω 1000GeV for all π in the nuclear reactions such as: N + Pb π N + Pb. Here, it is iportant to note that, for the nucleon laboratory oenta plab 80GeV/c, we predict that the all above SČR-pionic bands will be enlarged since the physical doain is given by v πph ( ω)/v1 Re n1 ( E1 ) cosθ Nπ 1 and Re nn( EN) 1 (see the results fro Fig. 4). (iii) The NPIČR-pions ust be coplanar with the incoing and outgoing projectile possessing a strong correlation between the angle of eission ( θ, ω ) and the pion ( ) T energies (see Fig. 3). ω and projectile ( p )

3 3 Mesonic Super-Čerenkov-like effects in hadronic and nuclear edia 709 Fig. 2 (a) Pionic refractive index, (b) The SČR-energy thresholds. (iv) For the ČB1 the NPIČR-differential cross section are peaked (see Ref. [4]) at the energy ω = 260 MeV for ČB1 band and ω = 930 MeV for ČB2 band when the absorption is neglected and the peak position is shifted up to ω = 240 MeV for ČB1-band when the absorption is taken into account. As we already entioned in Ref. [1], these predictions were experientally confired (see Fig. 10 in [1]) by the Dubna group (see E.K. Sarkisyan et al., Phys. Lett. B471 (1999) 257). So, they obtained a good agreeent with the position and width of the first pionic Čerenkov-like band predicted in Ref. [4]. (v) A suary of the theoretical results on pionic Super-Čerenkov-like radiation in (hadronic or nuclear) edia is presented in Fig. 4. The factor S is the spin factor while Θ( 1 cosθ SC ) is the Heaviside step function. In fact the entire quantu theory of the exotic decay: B1 ( p1, E1) π ( k, ω) B2 ( p 2, E2 ), where B 1 and B 2 are spin ½ baryons, can be developed just as in Ref. [4]. So, by using the inequality: cosθ SC v πph vbph 1, two general SČR-coherence conditions corresponding to the (esonic and baryonic) Čerenkov-like effects, are found (see Fig. 4) as two natural extrees of the sae spontaneous particles decays in ediu.

4 710 D.B. Ion, M.L. Ion 4 Fig. 3 [( θ1 k, ω) and ( θ1 k, Tp)] angle-energy correlations. (vi) Next, it is iportant to reark that the baryonic SČR-sector will appear especially for incident nucleons with p LAB higher than 100 GeV/c where we found that the baryonic SČR-conditions: and R v N ph ( E2) / v1 Re n1 ( E1) cosθ12 1 and Re n ( E N N ) 1, are satisfied with high accuracy. (vii) It is well known that the recent RHIC experients [6, 7] have shown two bup structure of the aziuthal distributions near the away-side jets. This structure was interpreted by Drein [8] as being the signature of the Čerenkov gluons. But, it is easy to see that, these two bup distributions can be interpreted in ore exact way: as signature of the two coponents of the SČR-gluons. However, the ore realistic interpretation of these experiental results as signature of the generalized esonic SČR-effects cannot be avoided. Of course ore theoretical and experiental investigations are necessary to clarify the probles of the generalized SČR-gluons eissions in hadronic edia. Acknowledgents. This research was supported by CNCSIS under contract ID /2007.

5 5 Mesonic Super-Čerenkov-like effects in hadronic and nuclear edia 711 Fig. 4 Suary of the theoretical results on pionic Super-Čerenkov-like radiation in (hadronic, nuclear) edia. REFERENCES 1. D.B. Ion and M.L. Ion, Ro. J. Phys. 55, No. 5 6 (2010). 2. D.B. Ion and M.L. Ion, Annals of Acadey of Roanian Scientist, Physics, 1, 47 (2009). 3. D.B. Ion and W. Stocker, Phys. Lett. B 273, 20 (1991); Phys.Rev. C 48, 1172 (1993); Lett. B 346, 172 (1995). 4. D.B. Ion and W. Stocker, Phys.Rev. C 52, 3332(1995). 5. M. Lax, Rev. Mod. Phys. 23, 287 (1951); L.L. Foldy, Phys. Rev. 67, 107 (1945). 6. J. Adas et al. (STAR Collaboration), Phys. Rev. Lett. 95, (2005). 7. S.S. Adler et al. (PHENIX Collaboration), Phys. Rev. Lett. 97, (2005). 8. I.M. Drein, Nucl. Phys. A767, 233 (2006). 9. D.B. Ion, Ro. Rep. Phys. 59, 1033 (2007).