Embed Size (px)
Citation preview
Our Universe : The Knowledge of
Ignorance
Ahmed M. Hamed Cairo, Egypt, December, 8th,
2011 1
“That’s where the money is”“Willie Sutton’s reasoning for robbing banks”
Why Science?
“-------------------------------------------------”We do science because
Similarly
2
3
Astronomy, Biology, Chemistry, Geology, Physics
Topic Size Mass/Energy First Appearance
Force and Phenomena
Macro-world
Observable Universe a 1028 cm. 1022 Msun 0 sec.Gravity + Unknown repulsive force; an
expanding space in the last 13.7x109 yrs, containing all the mass/energy of this world
Superclusters a 1026 cm. 1016 Msun 11x109 yr. Gravity; largest scale of lumpiness
Clusters of Galaxies a 1024 cm. 1015 Msun 6x109 yr. Gravity; galaxies in orbit around each other + dark matter
Galaxies a 1022 cm. 1011 - 1014 Msun 7x108 yr. Gravity; aggregation of stars, gas, dust and dark matter
Star Clusters a 1020 cm. 102 - 106 Msun 5x108 yr. Gravity; group of stars originated in an interstellar cloud
Planetary Systems a 1016 cm. 0.1-100 Msun 1.8x108 yr. Gravity; system of non-luminous bodies as by-product in stellar formation
Stars a 1011 cm. 0.1-100 Msun 1.8x108 yr. Gravity; contracting lump of gas with luminosity maintained by nuclear burning
Earth g 109 cm. 6x1027 gm. 9.5x109 yr. Gravity; a planet in the habitable zone of the Solar system
Living-world
Multicellular Organisms b 104 - 10-1 cm. 107 - 10-3 gm. 13.5x109 yr. Residual Electromagnetic force; organisms composed of multiple cells
Unicellular Organisms b 10-1 - 10-4 cm. 10-3 - 10-12 gm. 10.5x109 yr. Residual Electromagnetic force; one cell living unit
Micro-world
Molecules c 10-5 - 10-8 cm. 10 - 10-3 ev. 3.8x105 yr. Residual Electromagnetic force; structure formed by combination of atoms
Atoms c 10-8 cm. 10 ev. 3.8x105 yr. Electromagnetic force; system of electrons and nuclei
Nuclei p 10-13 cm. 109 ev. 1 sec. Residual strong force; system of neutrons and protons
Elementary Particles p 10-16 cm. > 10-3 - 1012 ev. < 10-32 sec. Weak, strong and electromagnetic forces; basic constituents of matter and force
QM
Gra
vity
QM
+ G
ravi
ty
4
Nobel Prizes in Physics
Usually for experiments, rather than theory Often shared, rather than individual
5
Setting the stage for Macro-worldTopic Size Mass/Energy First Appeara
nceForce and Phenomena
Macro-world
Observable Universe a 1028 cm. 1022 Msun 0 sec.Gravity + Unknown repulsive force; an
expanding space in the last 13.7x109 yrs, containing all the mass/energy of this world
Superclusters a 1026 cm. 1016 Msun 11x109 yr. Gravity; largest scale of lumpiness
Clusters of Galaxies a 1024 cm. 1015 Msun 6x109 yr. Gravity; galaxies in orbit around each other + dark matter
Galaxies a 1022 cm. 1011 - 1014 Msun 7x108 yr. Gravity; aggregation of stars, gas, dust and dark matter
Star Clusters a 1020 cm. 102 - 106 Msun 5x108 yr. Gravity; group of stars originated in an interstellar cloud
Planetary Systems a 1016 cm. 0.1-100 Msun 1.8x108 yr. Gravity; system of non-luminous bodies as by-product in stellar formation
Stars a 1011 cm. 0.1-100 Msun 1.8x108 yr. Gravity; contracting lump of gas with luminosity maintained by nuclear burning
Earth g 109 cm. 6x1027 gm. 9.5x109 yr. Gravity; a planet in the habitable zone of the Solar system
Gra
vity
QM
+ G
ravi
ty
How did we get here?
6
The Big Bang: Multiverse
So how big is the universe? No one knows if the universe is infinitely large, or even if ours is the only universe that exists.
8
Multiverse, UniverseFollowings is a more elaborated deduction with simple mathematics:
The radius of the observable universe is taken to be 4x1026 m. It is assumed that the matter in the universe consists of nucleons, which has a radius of about 2x10-13 m. Therefore, the universe has roughly 10118 partitions for the nucleons.These partitions can be filled or unfilled according to the configuration of the universe. The total number of different arrangements is 210118. A box with a radius of 210118x1026 m ~ 210118 m would exhausts all the possibilities. It contains possibly all kinds of parallel universes.Beyond that box, universes - including ours - must repeat. The identical parallel universe would be about 210118 m away as shown in Figure 02-12.
9
Our Universe
The observable universe is the space around us bounded by the event horizon - the distance to which light can have traveled since the universe originated. This space is huge but finite with a radius of 1028 cm. There are definite total numbers of everything: about 1011 galaxies, 1021 stars, 1078 atoms, 1088 photons. There is a hierarchy of structure: Everything is
10
Followings is a more elaborated deduction with simple mathematics:
The radius of the observable universe is taken to be 4x1026 m. It is assumed that the matter in the universe consists of nucleons, which has a radius of about 2x10-13 m. Therefore, the universe has roughly 10118 partitions for the nucleons.These partitions can be filled or unfilled according to the configuration of the universe. The total number of different arrangements is 210118. A box with a radius of 210118x1026 m ~ 210118 m would exhausts all the possibilities. It contains possibly all kinds of parallel universes.Beyond that box, universes - including ours - must repeat. The identical parallel universe would be about 210118 m away as shown in Figure 02-12.
Universe , Multiverse
11
Multiverse, Universe
So how big is the universe? No one knows if the universe is infinitely large, or even if ours is the only universe that exists.
12
Of the five senses in human to receive information about our environment, the sense of sight is the most important. Seventy percent of our sense receptors are devoted to the detection of light. This is not surprising in view of the dominant influence of Sunlight in our life. However, Sunlight occupies only a very small part of the electromagnetic spectrum which could shed information on various objects over the entire range (of the spectrum). It was only in the last hundred years that we were able to construct detectors for the retrieval of such information. Meanwhile we have also built telescopes to view distant
13
Of the five senses in human to receive information about our environment, the sense of sight is the most important. Seventy percent of our sense receptors are devoted to the detection of light. This is not surprising in view of the dominant influence of Sunlight in our life. However, Sunlight occupies only a very small part of the electromagnetic spectrum which could shed information on various objects over the entire range (of the spectrum). It was only in the last hundred years that we were able to construct detectors for the retrieval of such information. Meanwhile we have also built telescopes to view distant
objects and microscopes for investigating the very small. Observation of astronomical objects can now be carried out in space to bypass the atmospheric effects such as infrared absorption, air turbulence, and overcast sky etc. Experiment is a special kind of observation when the objects can be controlled by human manipulation. It can yield knowledge not obtainable in the natural environment. Some phenomena such as the quantum uncertainty, and time dilation cannot be attributed to the poor quality of instrument. They are inherent in natural.
14
Albert Einstein and the Fabric of Time Surprising as it may be to most non-scientists and even to some scientists, Albert Einstein concluded in his later years that the past, present, and future all exist simultaneously. In 1952, in his book Relativity, in discussing Minkowski's Space World interpretation of his theory of relativity, Einstein writes:Since there exists in this four dimensional structure [space-time] no longer any sections which represent "now" objectively, the concepts of happening and becoming are indeed not completely suspended, but yet complicated. It appears therefore more natural to think of
physical reality as a four dimensional existence, instead of, as hitherto, the evolution of a three dimensional existence.Einstein's belief in an undivided solid reality was clear to him, so much so that he completely rejected the separation we experience as the moment of now. He believed there is no true division between past and future, there is rather a single existence. His most descriptive testimony to this faith came when his lifelong friend Besso died. Einstein wrote a letter to Besso's family, saying that although Besso had preceded him in death it was of no consequence, "...for us physicists believe the separation between past, present, and future is only an illusion, although a convincing one."Most everyone knows that Einstein proved that time is relative, not absolute as Newton claimed. With the proper technology, such as a very fast spaceship, one person is able to experience several days while another person simultaneously experiences only a few hours or minutes. The same two people can meet up again, one having experienced days or even years while the other has only experienced minutes. The person in the spaceship only needs to travel near to the speed of light. The faster they travel, the slower their time will pass relative to someone planted firmly on the Earth. If they were able to travel at the speed of light, their time would cease completely and they would only exist trapped in timelessness. Einstein could hardly believe there were physicists who didn’t believe in timelessness, and yet the wisdom of Einstein's convictions had very little impact on cosmology or science in general. The majority of physicists have been slow to give up the ordinary assumptions we make about time.The two most highly recognized physicists since Einstein made similar conclusions and even made dramatic advances toward a timeless perspective of the universe, yet they also were unable to change the temporal mentality ingrained in the mainstream of physics and society. Einstein was followed in history by the colorful and brilliant Richard Feynman. Feynman developed the most effective and explanatory interpretation of quantum mechanics that had yet been developed, known today as Sum over Histories.Just as Einstein's own Relativity Theory led Einstein to reject time, Feynman’s Sum over Histories theory led him to describe time simply as a direction in space. Feynman’s theory states that the probability of an event is determined by summing together all the possible histories of that event. For example, for a particle moving from point A to B we imagine the particle traveling every possible path, curved paths, oscillating paths, squiggly paths, even backward in time and forward in time paths. Each path has an amplitude, and when summed the vast majority of all these amplitudes add up to zero, and all that remains is the comparably few histories that abide by the laws and forces of nature. Sum over histories indicates the direction of our ordinary clock time is simply a path in space which is more probable than the more exotic directions time might have taken otherwise.
Albert Einstein and the Fabric of Time Surprising as it may be to most non-scientists and even to some scientists, Albert Einstein concluded in his later years that the past, present, and future all exist simultaneously. In 1952, in his book Relativity, in discussing Minkowski's Space World interpretation of his theory of relativity, Einstein writes:Since there exists in this four dimensional structure [space-time] no longer any sections which represent "now" objectively, the concepts of happening and becoming are indeed not completely suspended, but yet complicated. It appears therefore more natural to think of
physical reality as a four dimensional existence, instead of, as hitherto, the evolution of a three dimensional existence.Einstein's belief in an undivided solid reality was clear to him, so much so that he completely rejected the separation we experience as the moment of now. He believed there is no true division between past and future, there is rather a single existence. His most descriptive testimony to this faith came when his lifelong friend Besso died. Einstein wrote a letter to Besso's family, saying that although Besso had preceded him in death it was of no consequence, "...for us physicists believe the separation between past, present, and future is only an illusion, although a convincing one."Most everyone knows that Einstein proved that time is relative, not absolute as Newton claimed. With the proper technology, such as a very fast spaceship, one person is able to experience several days while another person simultaneously experiences only a few hours or minutes. The same two people can meet up again, one having experienced days or even years while the other has only experienced minutes. The person in the spaceship only needs to travel near to the speed of light. The faster they travel, the slower their time will pass relative to someone planted firmly on the Earth. If they were able to travel at the speed of light, their time would cease completely and they would only exist trapped in timelessness. Einstein could hardly believe there were physicists who didn’t believe in timelessness, and yet the wisdom of Einstein's convictions had very little impact on cosmology or science in general. The majority of physicists have been slow to give up the ordinary assumptions we make about time.The two most highly recognized physicists since Einstein made similar conclusions and even made dramatic advances toward a timeless perspective of the universe, yet they also were unable to change the temporal mentality ingrained in the mainstream of physics and society. Einstein was followed in history by the colorful and brilliant Richard Feynman. Feynman developed the most effective and explanatory interpretation of quantum mechanics that had yet been developed, known today as Sum over Histories.Just as Einstein's own Relativity Theory led Einstein to reject time, Feynman’s Sum over Histories theory led him to describe time simply as a direction in space. Feynman’s theory states that the probability of an event is determined by summing together all the possible histories of that event. For example, for a particle moving from point A to B we imagine the particle traveling every possible path, curved paths, oscillating paths, squiggly paths, even backward in time and forward in time paths. Each path has an amplitude, and when summed the vast majority of all these amplitudes add up to zero, and all that remains is the comparably few histories that abide by the laws and forces of nature. Sum over histories indicates the direction of our ordinary clock time is simply a path in space which is more probable than the more exotic directions time might have taken otherwise.
16
17
18
The state of the “our” universeUniverse: everything that exists!
governed by the same physical laws and constants throughout most of its extent and history
Universe = invisible forms of (matter/energy) + visible (matter/energy)
76%76%
20%
Very nearly flat
13.7 billion years ago (Big Bang)
Isotropic
19
20
Dark Matter
there is not enough mass to hold the stars, galaxies and galaxy clusters in place, they are still moving around and would not disperse. It looks as if there is some kind of invisible force (gravity from the dark matter) to hold them together
Neutrino - It is a reasonable candidate for dark matter because of its unreactive nature. Theoretical calculations indicate that there should be as many as 100 million neutrinos for every atom in the universe. However, the recent estimates of neutrino mass is so slight that it could account for only about 0.1 - 7 per cent of the mass of the universe.
WIMP - Many new particles with heavy mass appear in the supersymmetry formulation. These are referred to as weakly interacting massive particles, or WIMPs. For example, the photino (the fermionic partner of photon) has a mass about 10 to 100 times that of the proton. Most of these electrically neutral particles would, like neutrino, go straight through Earth. On rare occasion, however, one might interact with an atom in the material they pass through. So far, the only claimed detection of a dark matter particle (by an Italian team in 2000) has been strongly disputed
neither emits nor scatters light or other electromagnetic radiation
21
Dark Energy
Our universe is expanding
is a hypothetical form of energy that permeates all of space and tends to accelerate the expansion of the universe.[
22
23
In 1922 Alexander Friedmann predicted the Big Bang cosmology, which portrays the universe as expanding space from a point where the matter-energy density was extremely high. The expansion can be visualized by a two dimensional analogy as shown in Figure 02-02. As the balloon expands, all the points on the surface recede from each other, and the wavelength on the surface is stretched. It is similar to the shift to longer wavelength when the source and receiver are moving away from each other. This phenomenon is called red shift of the spectrum because in visible light the shift to longer wavelength is toward the red colour. It plays a prominent role in discovering the cosmic expansion through the detection of the spectral line shift from distant galaxies.
Hubble determined the distances to the galaxies and the velocities that they were moving at, relative to Earth. From this, he discovered an amazing thing: the farther galaxies were away from us, the faster they were moving away from us. In other words, the Universe was expanding!
24
According to the latest cosmological model, the universe sprang into being about 14 billion years ago. At birth, the space was likely to have been curved and warped due to quantum effect within the tiny speck and time may be meaningless. After about 10-35 seconds, there began a brief period of exponentially fast expansion, known as inflation, that ironed out any curves or warps in space and made the universe flat (because it becomes so large). Inflation also predicts a much smaller initial region, which is required for smoothing out the distribution of matter and radiation, only leaving behind tiny quantum fluctuations that match the observed spatial variations in the cosmic microwave background radiation and provide the seeds for galaxy formation.
25
Note that according to inflationary cosmology, the entire universe is much bigger than the observable one (see Figure 02-01b, not to scale), and the confine of observable universe depends on the location. Observers living in the Andromeda galaxy and beyond have their own observable universes that are different from but overlap with ours.
26
27
The 2011 Nobel Prize in Physics is awarded "for the discovery of the accelerating expansion of the Universe through observations of distant supernovae" with one half to Saul Perlmutter and the other half jointly to Brian P. Schmidt and Adam G. Riess.The Science:In the 1920's, astronomer Edwin Hubble discovered that the universe was expanding. In 1998, two different research teams were trying to measure the expansion rate of the universe. One group was led by Saul Perlmutter, the other group by Adam G. Riess & Brian P. Schmidt. Both teams got a result that they didn't match expectations. They expected the expansion rate to be slowing down, but instead it was speeding up!The Big Deal:Albert Einstein's original work on general relativity had predicted an expanding universe, but he thought this was nonsense. He added a term to his equation, called the cosmological constant to remove this expansion. After Hubble discovered the expansion, Einstein (and many others) believed that the cosmological constant wasn't needed, so scientists spent years researching the expansion of the universe to prove that this term equaled zero. This research, however, proved that there was some sort of energy within the universe that is pushing it apart.More on Dark Energy:This energy, apparently inherent in the very fabric of the universe, is often called dark energy. Research performed over the last 13 years - including the WMAP research into the cosmic microwave background (CMB) radiation, which earned the 2006 Nobel Prize in Physics - has confirmed these results and, in fact, has indicated that dark energy makes up nearly 75% of the energy within our entire universe.How the Discovery was Made:The research teams looked for a certain type of supernova, called a supernova 1a, which happens when a white dwarf star gains enough extra matter to make it unstable. This sort of supernova is so powerful that it can outshine even a galaxy. Since we understand this sort of supernova well, it can be used as a "standard candle" to measure the distance to the supernovas and this measurement can be used to calculate the expansion rate of the universe over time.
76%
20%
The “visible” universe
Visible universe: ~ 150 billion galaxies
28
The Milky Way galaxy
Composed of 100,000 million Stars…
~ 13.2 billion years old
Visible universe contains ~ 1023 stars…
29
30
The solar system
The Sun: ~ 4.57 billion years old, 99.86% of the total mass of the solar system
The Earth: ~ 4.54 billion years old, life appeared on its surface ~ 1 billion years ago
31
From Macro- to Micro-world: The Atom
Basic unit of matterConsist of a dense central nucleus surrounded by a cloud of negatively charged electrons
Mproton ~ 1840 melectron
32
33
S. R.Space + Time Unified
34
Setting the Stage
Spcetime become curved = gravity
Black Holes, Expanding Universe
35
Setting the Stage
Waves <-> Particles
In fact no waves, but
Quantum Particles
Sometimes behaves as classical wavesSometimes like classical particles
Failure of classical Determinism
Uncertainty Principles
DletaXDeltaP ~ h DletaEDeltaT ~ h
Tunneling
Atoms and Matter Stability
36
Setting the Stage
Synthesis of SR + QM = QFT
Forces+predicts the antiparticles
Unification of Spacetime+QM doubled the world
37
Fundamental Change to notion of “vacuum”
GR made spacetime dynamical
QM+SR made vacuum dynamical
Thei resolve an odd clasical mystery: infinite energy of point electron
Due to e+e_ cloud, e- becomes effectively “fuzzy” at distances smaller than h/mec
Standard Model
38
3.0
0
eV
Na Atom
3.0
0
MeV
208Pb Nucleus
0.3
0
GeV
Proton
The Quarks
Strong force: ~ 98% of the visible mass of the universe
The origin of the mass? Dynamics origin for the (most) of the mass
Child-like question: What is the mass? Primary concept!
39
The Standard Model
Classical Mechanics
Quantum Mechanics
Special Relativity
Quantum Field Theory
It works from the Plank length to the edge of the universe
60 ORDERS OF MAGNITUDE
40
41
42
Why 3 families of fermions?
Origin of the masses of all fermions and W, Z bosons?
Does the Higgs boson exist?
Within every fermions family: more charge more mass
Are baryon number and lepton number strictly conserved?
What is the origin of CP viloation?
What is the origin of the mixture of lepton families PMS matrix and quark families CKM matrix?
What determine the magnitudes of the coupling constants?
Is it possible to unify the strong and electroweak interations?gravitation
43
Thrives on Crises+paradoxes, many of us feel thatOur current struggles are paving the way for a revolution in our understanding of physics on the same scale as those of Relativity + QM at the beginning of the 20’th century
Questions?The most important product of knowledge is ignorance
Why all three forces due to local symmetries?
Why is =1/137.0369999708..what it is?
Why are three families of quarks and leptons
Why is Mtop/Mup ~ 100,000
Why is space 3 dimension?
Why the forces look so different?
44
45
Symmetry breaking (Higgs mechanism)->MassSymmetry breaking ->Possibility of new symmetries
AntiScreening (Asymptotic freedom)->Quark confinement & unification
The vacuum?
The classical vacuum is empty
The quantum vacuum is full of fluctuating fields
46
The search for unification
String theory
47
SupersymmetryRotations in Superspace12 = - 21
x
y
t
Boson
Fermions
In supersymmetric theories for everyparticle there exists a super-partner
Quark
Squark
Electron Photon
PhotinoSelectron
Supersymmetry helps unify the forces
Supersymmetry helps explain the mass hierarchy
Supersymmetry predicts a candidate for dark matter
Why is Mw/MPlank ~ 10-16?
IF MSUSY ~ 1 TeV -> DM~ 90%
48
The most glaring limitation of QFT is its inability to incorporate gravity– the dynamics of space-time.Since the quantum fluctuations of space-time seem uncontrollable at the Plank scale---space-time foam
We must go beyond Einstien’s theory!
STRING THEORY
GRAVITY APPEARS AUTOMATICALLY
Quantum Gravity
49
The LHC machine
50
The LHC experiments (major)
51
52
USE EGYPT SUMMER SCHOOL
Physics at RHIC
53
New physics at RHIC
Nuclear density 0 ~ 0.15nucleons/fm3
Specific volume ~ 6fm3
Typical hadronic volume ~ 1-3 fm3
Is there new physics above ~ 30? Is there new physics above ~ 30?
The average inter-nucleon distance in the nucleus ~ 1.8fm
The partonic degrees of freedom are largely “frozen” in nuclear physics, Just as the nucleonic ones are frozen
in atomic physics.3.0
0
eV
Na Atom
3.0
0
MeV
208Pb Nucleus
0.3
0
GeV
Proton
54
Phase diagram of QCDF. Karsch, E. Laermann, A. Peikert, CH. Schmidt,
S. Stickan
Lattice QCD
~20%
D. d’Enterria and adapted from T. SchaferThe multiple facets of QCD 55
Physics opportunities at RHICBackward in time Study the formation and character
of QGP
The little Big BangSymmetries and (lack of symmetries) , Matter and
antimatter, etc…
Spin Physics
Proton’s spin crisis56
The RHIC machine
Crossing rate ~ 10 MHz
57
As in typical high energy physics experiments, detectors design is driven by the delivered
luminosity and DAQ.
Spectra Correlations
The current experiments
58
The STAR detector
Correlation machine: In full
At mid and forward At low and high pT
Considerable capabilities for particle identifications Reasonable efficiency for particle reconstructions
STAR probes 0.001 < x < 0.2 in PDF at s = 200 GeV
coverage of STAR detectors
ZDCZDC
WestEast
FHCFMSBEMC EEMC
FTPCFTPC TPC
BBCBBC TOF
MTD
HFT
PMD
FPD
FGT
59
The perfect liquid
60
Particle productions-high ptProduced from jet fragmentation of partons scattered with large Q2
Rates: framework of pQCD in terms of the asymptotically free pointlike parton
Dvac
c/h(z)
p+p or peripheral
Au+Au
Hard Scattering in vacuum-QCD
.
ab
h
c
o What about the FFs (Fragment distributions in jet energy)? in NN collisions and in AA collisions?
Central Au+Au
Gluon radiation and/orElastic scattering ?
Hard Scattering in QCD medium
med
c/hD(z)
Hadronic absorption?
Hadronization in/out medium? Formation
time?
o DIS off nuclei and Drell-Yan process on nuclear target: nPDF is universal and factorization holds up to
NLO. 61
Hadron suppression and di-jet results at mid rapidity
manifest the final state effect
AA collision is not simple incoherent superposition of neither NA nor NN collisions
?
Surface-bias
Hard scattering
4 < pT < 6 GeV/Ctrig
pT > 2 GeV/C
assoc
Spectra, correlation in rapidity and azimuth.
62
NS AS NS AS
More correlations and forward rapidity
non interacting jets
Consistent with saturation at low x Hard scattering8 < p
T < 15 GeV/Ctrig
63
Questions Mid Forward
Measurements Remarks
Is AA collision an incoherent
superposition of NN/NA collisions?
No ? Spectra and two/multi particle
correlations in and and
correlations w.r.t reaction plane
Final state effect,
surface bias emission?,
inconsistency with v2?
non-interacting
jets?, ridge?
Does NA collisions
resemble NN collisions?
Yes except for Croni
n effec
t
No Spectra and two particle
correlations in and
Onset of saturation at forward
rapidity
What is the role of the precursor
state, the proposed CGC, if
it exists?
? Onset of
saturation
Spectra and two particle
correlations in
Onset of saturation at forward rapidity,
CGC?
Interesting Physics
Summary 1
64
Spectra and correlations
Unexpected
level ofsuppression
for NPE
pre-hadronic collectivity
Neither unique hadronic nor partonic hierarchy over the entire pt range, only quark number order at
intermediate pT
65
LPM-effect based approaches: BDMPS & AMY
Opacity expansion: GLV & ASW
Medium enhanced higher twist effects
Medium modified MLLA
assumes that factorization holds and extract medium parameters.
Extracted parameters indicate a medium formation with much higher energy density than that of CNM.
Phenomenological studies of jet energy loss
Medium
q
E
L
form << form >> Static Medium Dynamic Medium
Scattering power of the medium q̂ q2=2/
Independent successive scattering centers1/ <<
Relative phase:dErad/dz CR s E <q
2>dErad/dz CR s ln(E) <q
2>
dErad/dz L2 dErad/dz L
The parton propagation is “time-ordered” and time-oredered perturbation theory is the natural framework to calculate the
radiation amplitude.Different models successfully describe the data with very different medium parameters ( q~3-19 GeV2/fm).
66
Questions Exp
Theory Measurements Remarks
Hadron suppression:
Hadronic absorption and/or partonic energy
loss?
? Partonic
energy loss for
light quark
Spectra and correlations w.r.t reaction plane for many identified
hadrons with different quarks
contents
Th: suppression is too large to be described by
hadronic absorption for light
quarks.Exp: Neither hadronic nor
partonic hierarchy, scaling with quark
number at intermediate pT
What is the mechanism of
energy loss (radiative/elastic)?
? ? Spectra, two particle correlations
in , and correlation w.r.t
reaction plane for heavy quarks
Exp: Unexpected level of
suppression for non-photonic
electrons.
What is the functional form of
energy loss (E,L,CR,f) ?
? E, ln(E),E,L2,L,
CR,f
Spectra and two particle correlations
in for direct photon spectra and
jet-hadron correlation in .
Exp: No strong dependence on E, L, CR,f is observed
Summary 2
67
Single hadron and di-jet analysis in NN, NA, and AA establish the final state effect in AA at mid and the onset
of saturation at forward . A particular focus was to discuss to what extent the high-pT particles produced (RHIC) can be taken as evidence for the RHIC paradigm of jet quenching “Parton traverses QDC medium (partonic matter) and
loses energy”.Measurements themselves do not establish unequivocal evidence for
partonic energy loss in partonic matter; however, Theory - experiment comparison seems to favor the partonic energy loss (light quarks) over
the hadronic absorptions in partonic and/or hadronic matter.
Whether AA creates a medium long-lived and extend over sizable volume and reached the thermodynamics limit to have
particular thermodynamic and transport properties.?!
The basic question
is awaiting future measurements of more evident results anddemanding theoretical progress
Conclusions
68
Physics at EIC
69
The role of gluons that bind us all
70
Gluons dominate low-x wave function
)201( xG
)201( xS
vxu
vxd
Scaling violation
71
The Issue With Our Current UnderstandingEstablished Model:
Linear DGLAP evolution scheme• Weird behavior of xG and FL from
HERA at small x and Q2 – Could signal saturation, higher twist effects, need for more/better
data?• Unexpectedly large diffractive cross-
sectionmore severe:Linear Evolution has a built in high energy “catastrophe”• xG rapid rise for decreasing x and
violation of (Froissart) unitary bound• must saturate
– What’s the underlying dynamics? Need new approach
72
The gluon density x*G(x,Q2) grows rapidly as collision energy increases.
Classical dynamics applies when the action is large:
=> Need weak coupling and strong fields
High gluon densityStrong classical fields
oCGC is the theory of shadowing !
Enhancement of QS with A non-linear QCD regime reached at significantly lower energy in A than in proton
Color Glass Condensate “saturation”
73
Matter at RHIC:
– thermalizes fast (t0 ~ 0.6 fm/c)
– We don’t know why and how? – Initial conditions? G(x, Q2)
Role of saturation ?– RHIC → forward region – LHC → midrapidity
• bulk (low-pT matter) & semi-hard jets
Jet Quenching:– Need Refererence: E-loss in cold
matter– No HERMES data for
• charm energy loss• in LHC energy range
Connection to RHIC & LHC Physics
RHICLHC
EIC provides new essential input:• Precise handle on x, Q2
74
Electron Ion Collider Concepts
• eRHIC (BNL): Add Energy Recovery Linac to RHICEe = 10 (20) GeVEA = 100 GeV (up to U)seN = 63 (90) GeVLeAu (peak)/n ~ 2.9·1033 cm-2 s-1
PHENIX
STAR
e-cooling (RHIC
II)
Four e-beam passes
Main ERL (2 GeV per pass)
Electron Cooling
Snake
Snake
IR
IReRHIC(Linac-Ring)
ELIC
ELIC (JLAB): Add hadron beam facility to existing electron facility CEBAFEe = 9 GeVEA = 90 GeV (up to Au)seN = 57 GeVLeAu (peak)/n ~ 1.6·1035 cm-2 s-1
Both allow for polarized e+p collisions !75
“That’s where the money is”“Willie Sutton’s reasoning for robbing banks”
“That’s where the Unknown is”We do these things because
Similarly
Why science?
76
77
Followings is a more elaborated deduction with simple mathematics:
The radius of the observable universe is taken to be 4x1026 m. It is assumed that the matter in the universe consists of nucleons, which has a radius of about 2x10-13 m. Therefore, the universe has roughly 10118 partitions for the nucleons.These partitions can be filled or unfilled according to the configuration of the universe. The total number of different arrangements is 210118. A box with a radius of 210118x1026 m ~ 210118 m would exhausts all the possibilities. It contains possibly all kinds of parallel universes.Beyond that box, universes - including ours - must repeat. The identical parallel universe would be about 210118 m away as shown in Figure 02-12.
Universe , Multiverse
78
Multiverse, Universe
So how big is the universe? No one knows if the universe is infinitely large, or even if ours is the only universe that exists.
79
Of the five senses in human to receive information about our environment, the sense of sight is the most important. Seventy percent of our sense receptors are devoted to the detection of light. This is not surprising in view of the dominant influence of Sunlight in our life. However, Sunlight occupies only a very small part of the electromagnetic spectrum which could shed information on various objects over the entire range (of the spectrum). It was only in the last hundred years that we were able to construct detectors for the retrieval of such information. Meanwhile we have also built telescopes to view distant
80
Of the five senses in human to receive information about our environment, the sense of sight is the most important. Seventy percent of our sense receptors are devoted to the detection of light. This is not surprising in view of the dominant influence of Sunlight in our life. However, Sunlight occupies only a very small part of the electromagnetic spectrum which could shed information on various objects over the entire range (of the spectrum). It was only in the last hundred years that we were able to construct detectors for the retrieval of such information. Meanwhile we have also built telescopes to view distant
objects and microscopes for investigating the very small. Observation of astronomical objects can now be carried out in space to bypass the atmospheric effects such as infrared absorption, air turbulence, and overcast sky etc. Experiment is a special kind of observation when the objects can be controlled by human manipulation. It can yield knowledge not obtainable in the natural environment. Some phenomena such as the quantum uncertainty, and time dilation cannot be attributed to the poor quality of instrument. They are inherent in natural.
81
82
