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)
Side SM: 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
Muon multiplicity
Zenith angle range (*)
Live time, (hour)
Number of events
 3
30 – 60
758
18137
 5
1296
8864
 10
2680
3272
 60
1552
4109
10102
6786 10
19922
2013
 75
395
(*) 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
θ = 65º : 1016 – 1018 eV
Large angles: around 1018 eV

19. Basic results
The following results based on local muon density spectrum measurements in the energy region 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 Xmax elongation 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, (2005); 96, (2006)

28. Centrifugal barrier
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.

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 GeV in 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-quark center-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 Baksan Underground Scintillation Telescope (BUST)

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

51. Conclusion
Results of NEVOD-DECOR and some other experiments in CR can be considered as an evidence
in favour of new physics existence above the knee.
The main feature of this new physics is appearance of an excess of very high energy muons (>100 TeV) in CR and their absence in collider experiments.
Therefore today we have a unique possibility to prove the existence of new physics in cosmic rays by using existing muon and neutrino detectors: BUST, NEVOD-DECOR, IceCube, Baikal, ANTARES, etc. before it will be done in accelerator experiments.

52. Thank you for attention!

53. Proposal of NEVOD-DECOR-EAS experiment

54. Calibration Telescope System (CTS)

55. CTS response for EAS with energy 1016 eV

56. Proposal of EAS array around NEVOD-DECOR

57. Cluster on the roof of one building

58. Results of EAS simulation (1016 eV)
NEVOD
EAS

59. Cosmophysical approach to results of EAS investigations
EAS energy is equal to the energy of primary particle.
All changes of EAS characteristics are results of energy spectrum or/and composition changes only.
Primary cosmic rays have galactic origin and their acceleration and keeping in Galaxy are determined by their charge Z or/and mass A.
But experimental results of N/Ne and Xmax measurements contradict this approach.
The problem of UHE cosmic ray origin is not clear.

60. Results of energy spectrum interpretation

61. Results of composition “investigations”
Really, N / Ne – ratio is measured.

62. Results of Xmax measurements

63. Relation between primary energy E1 and measured energy E2
where t is total energy of top-quarks in the center-of-mass system.
Threshold energy Eth, above which QGM blobs are produced, is determined by nucleus mass number Ai.
In principle, compound mass mc may depend on Ai and E1 > Eth , too.

64. Simplest model mc = constant = nmN.
where ln takes into account the increasing top-quark multiplicity and square root provides transition into the center-of-mass system.
n = 4
n = 4

65. Existing approach to EAS analysis

66. New approach to EAS analysis

67. The ankle problem

68. Explanation of the ankle appearance
On the face of it, the considered approach does not explain the behavior of the energy spectrum above the ankle, but this is not so.
With the increase of primary particle energy, the excitation level in blob of QGM can exceed the centrifugal barrier, and it will decay into light quarks.

69. Illustration of the ankle appearance
The knee
1017 eV
1018 eV
The ankle
In this case, there will be no missing energy and the measured spectrum begins to return to the initial form (g = 2.7) and to normal composition.

70. Solution of the ankle problem

71. The model of cosmic ray generation in plasma pinches
B.A.Trubnikov, V.P.Vlasov, S.K.Zhdanov
Kurchatov Institute, Moscow
(Preprint № 4828/6 IAE, M., 1989; JETP Lett., 1989, v.49, p.581.)
In cosmic plasma (of any origin) electrical discharges – "cosmic lightnings" can occur, at which cylindrical pinches are formed. Two basic instabilities of plasma pinches are known: snaky and neck.
In the last case plasma jets are squeezed out of pinch neck. These jets are the accelerated particle beams.
Snaky Neck

72. Energy spectrum of accelerated particles
It is shown that energy distribution of particles in jets has the following form:
which does not depend on pinch sizes, currents in pinches and other parameters.
These parameters determine a proportionality coefficient only.
Accelerated particle energy has no limitation since density in plasma pinch   when its radius  0.
Therefore the contribution of various sources of cosmic plasma (stars, Supernovae, AGN, Galaxies, etc.) can be summed and a general spectrum in the whole Universe is formed.