NEVOD-DECOR experiment and evidences of quark-gluon plasma in cosmic rays

1. 3rd RICAP, May 26, 2011 NEVOD-DECOR experiment and evidences of quark-gluon plasma in cosmic rays A.A.Petrukhin for Russian-Italian Collaboration National Research Nuclear University MEPhI, Russia Istituto di Fisica dello Spazio Interplanetario, INAF, Torino, Italy Dipartimento di Fisica Generale dell’ Universita di Torino , Italy Contents 1. New method of EAS investigations. 2. Experimental complex NEVOD-DECOR. 3. Results of muon bundle investigations. 4. Evidences of new physics in CR. 5. Model of QGP production. 6. Possibilities of new model check.

2. New method of EAS investigations

3. Methods of EAS investigations • Number of electrons Ne (in fact, mixture of charged particles) • Number of muons, N • Energy deposit of EAS core, Eh • Cherenkov radiation flux, FCh • Fluorescence radiation flux, Ff • Radio emission flux, Fr • Local muon density, D - results • Muon bundle energy, E - plans New!

4. Inclined EAS detection(local muon density measurements) Advantages: - practically pure muon component; - large area of showers, which increases with energy.

5. μ-EAS transverse section VS zenith angle Number of detected EAS depends on: shower array dimensions shower dimensions only

6. Traditional EAS detection technique (E ~ 1018 eV) ~ 500 m EAS counters (~ 1 m2)

7. Local muon density spectra detection technique E ~ 1018 eV, θ=80º Muon detector ~ 10 km

8. Contribution of primary energies at different zenith angles Wide angular interval – very wide range of primary energies !

9. Experimental complex NEVOD-DECOR

10. General view of NEVOD-DECOR complex Coordinate-tracking detector DECOR (~115 m2) Cherenkov water detector NEVOD (2000 m3) • SideSM: 8.4 m2 each • σx1 cm; σψ  1°

11. A typical muon bundle event in Side DECOR( 9 muons, 78 degrees) Y-projection X-projection

12. Muon bundle event (geometry reconstruction)

13. A “record” muon bundle event Y-projection X-projection

14. Muon bundle event (geometry reconstruction)

15. Results of muon bundle investigations

16. DECOR data. Muon bundle statistics (*) For zenith angles < 60°, only events in two sectors of azimuth angle (with DECOR shielded by the water tank) are selected.

17. Effective primary energy range Lower limit ~ 1015 eV (limited by DECOR area). Upper limit ~ 1019 eV (limited by statistics).

18. Local muon density spectra Low angles: around the “knee” θ = 50º : 1015 – 1017 eV Large angles: around 1018 eV θ = 65º : 1016 – 1018 eV

19. Basic results The following results based on local muon density spectrum measurements in the energy region 1015 - 1018 eV were obtained: - detection of the knee (this can be considered as energy scale calibration); - observation of the second knee; - some excess of muon bundles in comparison with predictions, which increases with energy. Important: Evidences for a similar excess of muons were found in some other EAS experiments.

20. Possible explanations • The excess of muon density with the increase of energy in the interval 1015 – 1018 eV can be explained by three reasons: • progressively heavier CR mass composition; • progressive deficit of muons in EAS simulated with commonly used interaction models; • inclusion of new processes of muon generation. • In the favour of the last approach evident many unusual events detected in CR experiments.

21. List of unusual events • In hadron experiments:  halos, alignment, penetrating cascades, long-flying component, large transverse momenta, Centauros, Anti-Centauros. • In muon experiments: excess of VHE (~ 100 TeV) single and multiple muons, observation of VHE muons, the probability to detect which is very small.  Important: Unusual events appear at PeV energies of primary particles. • From this point of view, results obtained in EAS investigations around the knee including uncertainties with mass composition can be considered as unusual, too:  change of EAS energy spectrum in the atmosphere, which is now interpreted as a change of primary energy spectrum. changes of behavior of N(Ne) and Xmax(Ne) dependences, which are now explained as indication of heavier composition. 

22. New physics in CR

23. What do we need to explain all unusual data? Model of hadron interactions which gives: • Threshold behaviour (unusual events appear at • several PeV only). • 2. Large cross section (to change EAS spectrum slope). • 3. Large yield of leptons (excess of VHE muons, missing energy and penetrating cascades). • 4. Large orbital (or rotational) momentum (alignment). • 5. More quick development of EAS (for increasing Nm / Ne ratio and decreasing Xmaxelongation rate).

24. Possible variants • Inclusion of new (f.e., super-strong) interaction. • Appearance of new massive particles (supersymmetric, Higgs bosons, relatively long-lived resonances, etc.) • Production of blobs of quark-gluon plasma (QGP) We considered the last model since it allows demonstrably explain the inclusion of new interaction.

25. Model of QGP production

26. Quark-gluon plasma • Production of QGP provides two main conditions: • - threshold behavior, since for that high temperature (energy) is required; • - large cross section, since the transition from quark-quark interaction to some collective interaction of many quarks occurs: where R, R1 and R2 are sizes of quark-gluon blobs. 2. But for explanation of other observed phenomena a large value of orbital angular momentum is required.

27. Orbital angular momentum in non-central ion-ion collisions Zuo-Tang Liang and Xin-Nian Wang, PRL 94, 102301 (2005); 96, 039901 (2006)

28. As was shown by Zuo-Tang Liang and Xin-Nian Wang, in non-central collisions a globally polarized QGP with large orbital angular momentum which increases with energy appears. • In this case, such state of quark-gluon plasma can be considered as a usual resonance with a large centrifugal barrier. • Centrifugal barrier will be large for light quarks but less for top-quarks. Centrifugalbarrier

29. Centrifugal barrier for different masses

30. How interaction is changed in frame of a new model? • Simultaneous interactions of many quarks change the energy in the center of mass system drastically: where mcnmN. At threshold energy, n ~ 4 ( - particle). • Produced -quarks take away energy GeV, and taking into account fly-out energyt> 4mt  700 GeVin the center of mass system. • Decays of top-quarks: ; W –bosons decay into leptons (~30%) and hadrons (~70%); b  c  s  u with production of muons and neutrinos.

31. Muon energy spectrum from top-quarks

32. How CR energy spectrum is changed? • One part of t-quark energy gives the missing energy (e, , , ), and another part changes EAS development, especially its beginning, parameters of which are not measured. • As a result, the measured EAS energy E2 will not be equal to primary particle energy E1 and the measured spectrum will be different from the primary spectrum. 3. Transition of particles from energy E1 to energy E2 gives a bump in the energy spectrum near the threshold.

33. Change of primary energy spectrum

34. How measured composition is changed in frame of the new approach Since for QGP production not only high temperature (energy) but also high density is required, threshold energy for production of new state of matter for heavy nuclei will be less than for light nuclei and protons. Therefore heavy nuclei (f.e., iron) spectrum is changed earlier than light nuclei and proton spectra!!!

35. Primary spectra of various nuclei

36. Measured spectra for some nuclei and spectrum of all particles

37. Influence of energy straggling

38. Comparison with experimental data (with 10% straggling)

39. Discussion of results • Considered approach allows explain all unusual results obtained in cosmic rays including their energy spectrum and mass composition behavior. 2. Simplest model of energy spectrum surprisingly well describes experimental data. 3. Observed changes of composition are explained: • a sharp increase of average mass at the expense of detection of EAS from heavy nuclei, • after that, slow transition to proton composition.

40. Possibilities of new model check

41. How to check the new approach? There are several possibilities to check the new approach as in LHC experiments so in cosmic ray investigations. Of course, corresponding results can be obtained in LHC experiments, since QGP with described characteristics (excess of t-quarks, sharp increasing of missing energy, etc.), doubtless, will be observed. It is possible that some proof of this approach has been already obtained in lead-lead interactions at LHC (imbalance of jet energies in heavy ion collisions).

42. ATLAS observes striking imbalance of jet energies in heavy ion collisions(CERN Courier, January/February 2011) Highly asymmetric dijet event Dijet asymmetry distributions

43. How to explain the ATLAS results in frame of considered approach? t W + + b In the top-quarkcenter-of-mass system: Tb ~ 65 GeV, TW ~ 25 GeV. If to take into account fly-out energy, Tb can be more than 100 GeV. In the case if b gives a jet and W ~ 20 , the ATLAS experiment’s picture will be obtained. But it is necessary to remark that to give exhaustive explanation of events observed in LHC experiments is very difficult.

44. How to check the new approach in cosmic ray experiments? One possibility is direct measurements of various nuclei spectra in space. Changes in spectra must begin from heavy nuclei. Two other possibilities are connected with VHE muon detection: - measurements of muon energy spectrum above 100 TeV; - measurements of energy deposit of EAS muon component below and above the knee. For that, existing muon and neutrino detectors can be used: BUST, IceCube, NEVOD-DECOR, Baikal, ANTARES, etc.

45. Prediction for CR nuclei spectra measurements

46. Preliminary results of muon energy spectrum investigations in BaksanUnderground Scintillation Telescope (BUST)http://arxiv.org/pdf/0911.1692

47. IceCube results Bundle Data High pT Muon Double Coincident CRs High pT Muons Single Showers

48. Response of NEVOD for muon bundles

49. Energy deposit of muon bundles

50. Average energy of EAS muons in dependence on zenith angle and local muon density