Some remarks about UHECR origin and interaction

1
Some remarks about UHECR origin and
interaction
A.A.Petrukhin Moscow Engineering Physics
Institute CRIS 2006
Contents
1. Two approaches to the problem 2. Generation
of CR in plasma pinches 3. Unusual events in
UHECR 4. New physics in cosmic rays 5.
CR energy spectrum description 6. Conclusions
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Introduction

• UHECR problems begin from VHECR problems (in the
  first turn from the knee).
• Experimentally the knee is observed as the change
  of the slope in EAS energy spectrum in the
  atmosphere.
• But EAS is a secondary phenomenon and its energy
  can differ from the energy of primary particle.
• Therefore in principle two approaches are
  possible.

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1. The knee exists in primary CR

• In favour of this approach two basic
  arguments were usually given
• Sources and processes of CR generation without
  the knee were unknown (the knee energy is a
  limiting energy of galactic cosmic rays).
• There were no experimental evidences in
  accelerator physics for inclusion of new physical
  processes with relatively large cross-section,
  which is necessary for the knee formation due to
  interaction processes.

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2. The knee appears at interactions of primary
CR in the atmosphere

• In favour of this approach, three basic
  arguments can be given
• Model of CR generation in plasma pinches, which
  predicts infinite energy spectrum with a single
  slope .
• Many experimental observations of unusual events
  and phenomena above the knee.
• New experimental and theoretical results on QGP
  behavior at the energy increase (growth of yield
  of heavy particles, large orbital momentum at
  non-central collisions, etc.).

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CR generation in plasma pinches(B.A.Trubnikov
et al.)
This model was considered at previous CRIS 2004
and has been published in its Proceedings Nucl.
Phys. B (Proc. Suppl.) 136 (2004) 218-223 where
the references to the original papers of authors
(B.A.Trubnikov V.P.Vlasov, S.K.Zhdanov ) are
given. Therefore I mention the main ideas and
results only.
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CR generation in plasma pinches
In cosmic plasma (of any origin) electrical
discharges "cosmic lightnings" can occur, at
which cylindrical pinches are formed.
Plasma jets are squeezed out of pinch neck. These
jets are accelerated particle beams.

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CR generation in plasma pinches
Energy distribution of particles in jets has
the form
which does not depend on pinch sizes, currents in
pinches and other parameters, which determine a
proportionality coefficient only. Model
has no limitation for accelerated particle energy
since in plasma pinch neck
density ? ? ?, when its radius r ? 0.
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Other interesting consequences

• The composition of accelerated particles will be
  the same as composition of cosmic plasma, which
  consists mainly of hydrogen.

• Model explains the absence of point sources of
  cosmic rays since pinches, f.e. near Supernova,
  can be oriented in any direction.

• At the same time, generation of particles in
  narrow jets in cylindrical pinches can explain
  the appearance of correlated particles.
• In comparison with other models, which work
  during SN explosions only, this mechanism works
  permanently, therefore it has to be considered as
  main source of CR.

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List of unusual events

• In hadron experiments

halos, alignment, penetrating cascades, Centauros
(Pamir-Chacaltaya)
?
?
long-flying component, Anti-Centauros (Tien-Shan).

• In muon experiments

excess of VHE ( 100 TeV) single (MSU) and
multiple (LVD) muons
?
observation of VHE muons (Japan, NUSEX), the
probability to detect which is very small.
?

• In EAS investigations

change of EAS energy spectrum in the atmosphere,
which is explained now as a change of primary
energy spectrum.
?
changes of behavior of N?(Ne) and Xmax(Ne)
dependences, which are explained now as the
heaving of CR composition.
?
It is important All these events appear at PeV
energies of primary particles.
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Alignment
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Penetrating cascade
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Muon flux excess
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Muon bundles excess
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The knee in EAS energy spectrum
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Missing energy determination
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(No Transcript)
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Mean ltln Agt obtained from Nm/Ne ratio
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Xmax
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What we need to explain these 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
  and missing energy).
• 4. Large orbital (or rotational) momentum
  (alignment).
• 5. Violation of isotopic invariance (Centauros
  and Anti- Centauros) .
• Two possible models are suitable for that.

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New massive short-lived particles(as usual
resonance states)
Pluses 1. According to Chew-Frautschi
diagram, spin J depends on mass M as J 0.9 M 2,
where M is in Gev. For M 1
TeV, spin J will be 106 (!) 2. This very
large value of J can explain - a long
life-time of new resonance state, which is
necessary for decays into weakly interacting W,
Z-bosons - experimental results on alignment
observations.
Minus 1. Small cross-section of such
particle production
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Chew-Frautschi diagram
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Quark-gluon plasma(better, Quark-gluon matter)
gives

• Threshold behavior, since high temperature and
  density are required.
• 2. Large cross section, since transition from
  quark-quark interaction to some collective
  interaction of many quarks gives
  .
• 3. As was shown by Zuo-Tang Liang and Xin-Nian
  Vang in non-central collisions a globally
  polarized QGP with large orbital angular
  momentum must appear.
• Centrifugal barrier
  will be less for heavy particles (quarks and
  W, Z-bosons), which are necessary to explain
  leptons production.

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Potential barrier for different masses
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Some remarks about composition
1. At present, information about the composition
is
extracted from results of EAS investigations,
namely from data on the number of muons N?
and Xmax elongation rate, taking into
account results of simulations. 2. If new
state of matter with mass 1 TeV is
generated, the number of secondary particles will
be increased due to decays of W, Z-bosons
into hadrons (on average 20 in each). 3.
This leads to a more quick development of shower
(decreasing of Xmax) and to increasing N?.
4. Taking into account a missing energy, instead
of proton shower with energy E0, "iron"
shower with lower energy will be observed.
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How to explain the ankle appearance?

• With increasing of interaction energy, mass and
  energy of excitation of resonance state can be so
  large that it begins to decay into hadrons
  immediately.

• Average missing energy and number of muons will
  be decreased and the development of EAS will
  return to a normal behavior.

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Region of missing energy
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Cut-off influence existing approach
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Cut-off influence new approach
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Two versions of cut-off influence
?
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Conclusions

• Consideration of UHECR spectrum and interaction
  shows that there is a very close interconnection
  between them.
• New model of CR acceleration in plasma pinches
  and a possibility of generation of quark-gluon
  plasma resonances with large angular momentum
  allow to formulate a new approach to UHECR
  description.
• This approach shows that it is impossible to
  solve problems of UHECR (especially of
  GZK-cutoff) without the solution of the knee
  problem.

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Addendum-1

• To obtain unambiguous solution of VHE, UHE, and
  EHE CR problems it is necessary to investigate
  them at one array by unified methods beginning
  from 1 PeV or lower.
• 2. The array must include various detectors
  for measurements of all EAS component
  characteristics and especially muon energy in the
  range more than 10 TeV.
• In fact, it is necessary to construct the united
  world-wide cosmophysical array like LHC in
  accelerator physics.
• In opposite case we will discuss problems of the
  knee, the ankle and cutoff 50 years more (in
  2008, it will be 50 years from the knee
  discovery).

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Addendum-2

• 5. Apparently the best country for deployment
  of this united array is USA. In this case even
  some equilibrium appears
• - in Europe the biggest accelerator,
• - in USA the biggest cosmophysical
  observatory.