Elementary Particles Presented

  • #51
Five "socalled" Easy Pieces !

Hey, guys and girls,

I have written a little and simple text in order to eliminate some common misconceptions of QFT (well QM too ofcourse).

NUMBER ONE:
Besides, i would like to add this : people always ask how do electrons orbiting the nucleus prevent from falling in ? Well, this question itself contains incorrect formulations. the electron does NOT orbit the nucleus. Just look at the lowest energy orbital : the s-orbital. It is a sphere around the nucleus. So , prior to any kind of measurement, the electron is basically everywhere around the nucleus.
Same goes for any other orbital (ofcourse the have another shape)

QM proves us that the kinetic energy is higher when being closer to the nucleus, but the potential energy is lower (more negative). The sum of these two really yields a stable equilibrium throughout all energy levels.


NUMBER TWO:
People always mix QFT with QM. A wave function that describes an electron is not a wave that IS an electron. It just contains the electron-properties. This is QM

In QFT, particles arise as fluctuations of fields but the fields themselves ARE NOT particles. Particles arise (and also forces) as actual vibrations of these fields. Just think of the mattress analogy that i have used throughout my entire journal


NUMBER THREE:
An electron has a spin (intrinsic angular momentum), but it does NOT actually rotate around its axis, guys. The 'rotational nature' of spin comes from the behavior of the Dirac wavefunction (this is a matrix that represents a physical state and arises when solving the Dirac equation. This equation describes a fermion : a particle with non-integer spin) under coordinate-transformations (which are called the rotations).

With behavior i mean : how does the physics change if we interchange the components of this Dirac spinor, if we change the parity, if we apply coordinate transformations to the wavefunction and so on...For example, if we rotate the wavefunction 360°, do we still get the same physical laws...You see the pattern ?

It is this specific behavior that yields the name SPINOR because if you rotate it 360°, you get the opposite value. Now, changing coordinates (represented by rotations) and looking how the physics changes or not, is NOT THE SAME as actually rotating. So, spin arises thanks to symmetries involved but there is no actual rotation.

ps : be sure that you know what 'intrinsic' means


NUMBER FOUR:
Finally : there ain't two ways of describing light : The particle wave-duality exists only because of our 'classical minds' ; we want to think in terms of either particles or waves. There is no problem with that but we do need to keep the correct perspective on things here. First of all 'particles' in this case does not mean little objects with finite boundaries. It means little finite pieces of energy (this is the actual quantization , right ?)

Secondly, in QM we have experiments that are better explained with the wave-like notion (eg the double slit experiment) and we have those experiments that are better described with the particle-like notion (eg photo-electric effect). However in the end both descriptions are just ONE SINGLE way of describing the physical properties of light...that is all.


NUMBER FIVE:
Another common misconception is the fact that the photo-electric effect proved the existence of photons. That is not true because this photo-electric effect can be described in terms of the wavelike-notion of the incident EM-radiation too. It is only the atoms of the target electrode that are treated with QM. However, the particle-like notion of light is suggested by this experiment. If you want to read more, check out my journal and find the article on creating an entangeled photon-state in an undergrad lab

Here's the article : Create entangled photons yourself in an undergrad laboratory :
http://marcus.whitman.edu/~beckmk/Q...r/Thorn_ajp.pdf


regards
marlon
 
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  • #52
Shortest Standard Model-summary ever !

Standard Model : SU(3)xSU(2)xU(1) gauge theory
Gauge bosons : 8 SU(3) color-coupled gluons, 3 SU(2) 2 W\'s and 1 Z-boson, 1 U(1) B the foton

In the unbroken SU(2)xU(1) gauge theory of the electroweak interactions, there are four fields. These fields are usually called W1, W2, W3, (from SU(2)) and B (from U(1))

After spontaneous symmetry breaking due to the Higgs mechanism, you still have four fields, but three of them gain masses. The W1 and W2 mix to form the W+ and W- and the W3 mixes with the B to form the Z0. The rest of the W3-B mix remains massless and is the photon (often called A and belonging to the remnant U(1) symmetry of QED).


Three generations of spinor fermions divided into:
1) colored doublet left-quarks (ups and downs)
2) doublet left-leptons (electrons and neutrinos)
3) colored right-ups
4) colored right-downs
5) right-electrons
with various hypercharges

The singlet states correspond to particles that don't feel the weak force like 3,4 and 5...

Or you can classify like this :

Mass Particles

---A. Six quarks
------1. Up, down, strange, charm, top, bottom
------2. Combine to form Hadrons in two varieties: baryons, mesons

---B. Six leptons
------1. Three with charge (Tau, muon, electron)
------2. Three neutrinos each corresponding to a charged lepton
------3. Decay, don't combine

II. Three types of interactions mediated by force particles

---A. Strong (gluons)
---B. Electroweak
------1. Electromagnetic (photon)
------2. Weak (Z, W+, W- bosons)
---C. Gravity (graviton?)

Can you understand "the why" of this classification ?
marlon
 
  • #53
marlon said:
---A. Six quarks
------1. Up, down, strange, charm, top, bottom
------2. Combine to form Hadrons in two varieties: baryons, mesons

---B. Six leptons
------1. Three with charge (Tau, muon, electron)
------2. Three neutrinos each corresponding to a charged lepton
------3. Decay, don't combine

Can you understand "the why" of this classification ?
marlon

No.

I can not understand why the leptons are classified according electric charge, but the quarks are not.
 
  • #54
The quarks are classified like the leptons.
The quarks come in 3 doublets. (u,d),(c,s),(t,b).
In each doublet the upper quark has a charge +e more than the lower quark.
This is just like the leptons. Details are related to the groups involved.
The group structure is S(3)XSU(2)XU(1).
Why the quarks are +2/3 and -1/3 is involved with hypercharge and group details.
If the GUT is SU(5), the breakdown into this structure is unique,
but th proton decays.
 
  • #55
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  • #56
The Particle Adventure

Let's start the elementary particle journey

http://particleadventure.org/particleadventure/

regards
marlon
 
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  • #58
  • #59
Some short articles on particle physics from American Institute of Physics - Physics News - http://Newton.ex.ac.uk/aip/catagories/particle_physics.html
 
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  • #61
News from the particle physics world -

http://www.interactions.org/cms/
 
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  • #62
Check http://nobelprize.org/physics/laureates/2004/index.html if you want to find out more on the concept of asymptotic freedom in QCD. You need to click on "Nobel Lectures" to read what the 2004 Nobel Laureates in Physics have to say on it.

PS : Did you guys know that the guy in the middle actually played in a movie with Paul Newman ?

regards
marlon
 
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  • #63
If you want to have a very http://nobelprize.org/physics/laureates/1999/index.html in renormalization theory of the weak interaction, just read the Nobel Lecture of Gerardus 't Hooft, the 1999 Physics Nobel Prize Laureate.

Enjoy


regards
marlon
 
  • #66
GEANT4 User Document - Physics Reference Manual

This is really cool!

http://geant4.cern.ch/G4UsersDocuments/UsersGuides/PhysicsReferenceManual/html/PhysicsReferenceManual.html
 
  • #68
Hi everyone,

I was earlier today searching for online video material for students who asked me where to find it. I admit that such lectures are much more pleasant to follow than textbooks, although I myself never find the need for video material. The best would be to actually be able to attend the lecture interactively. In any case, it did not occur to me at first, but CERN as an amazing server full of countless presentations on all sorts of topics. Soome of them of incredible value.

You will find them by browsing their web server[/color]. Enjoy :smile:

Praising thanks to this wonderful initiative.
 
  • #69
Revealing the Hidden Nature of Space and Time:
Charting the Course for Elementary Particle Physics
http://www.nap.edu/catalog.php?record_id=11641

Principal Chapters:

1. The Scientific Excitement and Challenges 17-32
2. Key Questions in Particle Physics 33-55
3. The Experimental Opportunities 56-100
4. The Strategic Framework 101-117
5. Findings and Recommended Actions 118-135

As part of the Physics 2010 decadal survey project, the National Research Council was asked by the Department of Energy and the National Science Foundation to recommend priorities for the U.S. particle physics program for the next 15 years. The challenge faced in this study was to identify a compelling leadership role for the United States in elementary particle physics given the global nature of the field and the current lack of a long-term and distinguishing strategic focus. Revealing the Hidden Nature of Space and Time provides an assessment of the scientific challenges in particle physics, including the key questions and experimental opportunities, the current status of the U.S. program and the strategic framework in which it sits and a set of strategic principles and recommendations to sustain a competitive and globally relevant U.S. particle physics program.
 
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  • #70
Course notes on particle physics and standard model.

http://physics.uoregon.edu/~jimbrau/physics.html

Three part program on Elementary Particle Phenomenology:

Physics 661, Fall 2003 -
  • Introduction to the particles, forces, and the observable universe
  • Cosmic Rays
  • Quarks and Leptons
  • Interactions and Fields
  • Invariance Principles and Conservation Laws
  • Quarks in Hadrons
  • Lepton and Quark Scattering
Physics 662, Winter 2004 -
  • Quark Interactions and QCD
  • Weak Interactons
  • Cosmic Neutrinos
  • Electroweak Interactions and the Standard Model
  • Physics Beyond the Standard Model
  • Relativity and Cosmological Models
Physics 663, Spring 2004 -
  • particle accelerator concepts
  • experimental particle physics detector techniques
  • search for gravitational radiation



From his course - Physics 610 - Collider Physics:

"The Standard Model in 2001,'' Jonathan Rosner
Lectures at the 55th Scottish Universities' Summer School in Physics, St. Andrews
http://arXiv.org/abs/hep-ph/0108195
particularly sections 1 through 2.2
.
"Introduction to Electroweak Symmetry Breaking,'' Sally Dawson
Lectures given at the 1998 Summer School in High Energy Physics and Cosmology, Trieste, Italy
http://xxx.lanl.gov/abs/hep-ph/9901280
.
"Beyond the Standard Model,'' Michael Peskin
Lectures presented at the 1996 European School of High-Energy Physics
http://xxx.lanl.gov/abs/hep-ph/9705479
 
  • #71
Some historical background on HEP.


The discovery of the tau lepton: Part 1, The early history through 1975; Part 2, Confirmation of the discovery and measurement of major properties, 1976--1982; Perl, M. L.; February 01, 2000; SLAC-PUB--6584; ACC0025
http://www.osti.gov/accomplishments/documents/fullText/ACC0025.pdf


Discovery of charm; Goldhaber, G.; November 29, 1999; LBL--18696; ACC0023
http://www.osti.gov/accomplishments/documents/fullText/ACC0023.pdf


The hydrogen bubble chamber and the strange resonances; Alvarez, L.W.; November 29, 1999; LBL--22392; ACC0021
http://www.osti.gov/accomplishments/documents/fullText/ACC0021.pdf


The discovery of the top quark; Sinervo, P.K.; November 19, 1999; FNAL/C--95/371-E; ACC0015
http://www.osti.gov/accomplishments/documents/fullText/ACC0015.pdf


The discovery of the b quark at Fermilab in 1977: The experiment coordinator's story; Yoh, J.; October 26, 1999; FNAL/C--97/432-E; ACC0013
http://www.osti.gov/accomplishments/documents/fullText/ACC0013.pdf


Delta: the first pion nucleon resonance - its discovery and applications; Nagle, D.; October 26, 1999; LALP--84-27; ACC0011
http://www.osti.gov/accomplishments/documents/fullText/ACC0011.pdf


The ultimate structure of matter: The high energy physics program from the 1950s through the 1980s; ; January 19, 1999; DOE/ER--0435; ACC0005
http://www.osti.gov/accomplishments/documents/fullText/ACC0005.pdf


More at - http://www.osti.gov/accomplishments/databasebrowse.html
 
  • #72


I stumbled across this huge resource while looking for information on CMB and CMB-frame. These are all in downloadable PDF format.

http://pdg.lbl.gov/2008/reviews/contents_sports.html

Categories:
  • Constants, Units, Atomic and Nuclear Properties
  • Physical constants (Rev.)
  • Astrophysical constants and parameters (Rev.)
  • International System of units (SI)
  • Periodic table of the elements (Rev.)
  • Electronic structure of the elements
  • Atomic and nuclear properties of materials (Rev.) PDF / Interactive
  • Electromagnetic relations
  • Naming scheme for hadrons


Standard Model and Related Topics
  • Quantum chromodynamics
  • Electroweak model and constraints on new physics (Rev.)
  • Cabibbo-Kobayashi-Maskawa quark-mixing matrix (Rev.)
  • CP violation (Rev.)
  • Neutrino mass, mixing, and flavor change (Rev.)
  • Quark model (Rev.)
  • Grand Unified Theories
  • Structure Functions (Rev.; see below for more figures)
  • Structure Functions--additional figures (Rev.; see above)
  • Fragmentation functions in e+e- annihilation and lepton-nucleon DIS (Rev.)
  • Tests of Conservation Laws
  • CPT Invariance Tests in Neutral Kaon Decay (New)
  • CP Violation in KS -> 3pi
  • CP Violation in KL Decays (Rev.)
  • V(ud), V(us), Cabibbo Angle, and CKM Unitarity (Rev.)
  • Determination of V(cb) and V(ub) (Rev.)


Particle Properties (Hypothetical particles are listed below.)
  • Gauge Bosons
  • The Mass of the W Boson (Rev.)
  • Triple Gauge Couplings
  • Anomalous W/Z Quartic Couplings
  • The Z Boson (Rev.)
  • Anomalous Z Z gamma,
  • Z gamma gamma, and Z Z V Neutral Couplings

- Charged Leptons
Muon Anomalous Magnetic Moment (Rev.)
Muon Decay Parameters (Rev.)
tau Branching Fractions (Rev.)
tau-Lepton Decay Parameters (Rev.)

- Neutrinos
Number of Light Neutrino Types (Rev.)
Neutrinoless Double-beta Decay (Rev.)
Solar Neutrinos Review (Rev.)

- Quarks
Quark Masses (Rev.)
The Top Quark (Rev.)

- Mesons
Note on Scalar mesons (Rev.)
The eta(1405), eta(1475), f_1(1420), and f_1(1510) (Rev.)
Rare Kaon Decays (Rev.)
K(l3)+- and K(l3)0 Form Factors (Rev.)
CPT Invariance Tests in Neutral Kaon Decay (New)
CP-Violation in KS -> 3pi
V(ud), V(us), Cabibbo Angle, and CKM Unitarity (New)
CP-Violation in KL Decays (Rev.)
Dalitz-Plot Analysis Formalism
Review of Charm Dalitz-Plot Analyses (Rev.)
D0-- Dbar0 Mixing (Rev.)
Decay Constant of Charged Pseudoscalar Mesons (new)
Production and Decay of b-flavored Hadrons (Rev.)
Polarization in B Decays (Rev.)
B0-- Bbar0 Mixing (Rev.)
Determination of V(cb) and V(ub) (Rev.)
Branching Ratios of psi(2S) and chi_c(0,1,2) (Rev.)

- Baryons
Baryon Decay Parameters
N and Delta Resonances
Pentaquarks (New)
Radiative Hyperon Decays
Charmed Baryons (Rev.)
Lambda(c)+ Branching Fractions

- Hypothetical Particles and Concepts
Searches for Higgs Bosons (Rev.)
Free Quark Searches
Magnetic Monopole Searches
Supersymmmetry: Theory (Rev.)
Supersymmmetry: Experiment (Rev.)
Dynamical Electroweak Symmetry Breaking (Rev.)
Searches for Quark and Lepton Compositeness
Extra Dimensions (Rev.)
Axions and Other Very Light Bosons (New)
The W' Searches (Rev.)
The Z' Searches (Rev.)
The Leptoquark Quantum Numbers (New)


Astrophysics and Cosmology
  • Experimental tests of gravitational theory (Rev.)
  • Big-Bang cosmology (Rev.)
  • Big-Bang nucleosynthesis (Rev.)
  • Cosmological parameters (Rev.)
  • Dark matter (Rev.)
  • Cosmic microwave background (Rev.)
  • Cosmic rays (Rev.)


Experimental Methods and Colliders
  • Accelerator physics of colliders
  • High-energy collider parameters (Rev.)
  • Passage of particles through matter (Rev.)

Particle detectors (Rev.)
  • Radioactivity and radiation protection (Rev.)
  • Commonly used radioactive sources

and related - http://pdg.lbl.gov/2008/AtomicNuclearProperties/index.html - but I don't know where to put it at the moment.


Mathematical Tools
  • Probability (Rev.)
  • Statistics (Rev.)
  • Monte Carlo techniques (Rev.)
  • Monte Carlo particle numbering scheme (Rev.)
  • Clebsch-Gordan coeff., sph. harmonics, and d functions
  • SU(3) isoscalar factors and representation matrices
  • SU(n) multiplets and Young diagrams


Kinematics, Cross-Section Formulae, and Plots
  • Kinematics (Rev.)
  • Cross-section formulae for specific processes (Rev.)
  • Plots of cross sections and related quantities (Rev.) PDF / Interactive


Authors, Introductory Text, History plots
 
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  • #73
marlon said:
Hi everyone...

I have answered already a lot of questions here on the topic of the different elementary particles in the Standard Model. For this reason I will give the interested reader this site that describes this subject very clearly...

http://pdg.web.cern.ch/pdg/particleadventure/frameless/startstandard.html

If you have more questions, please don't hesitate to post them here...

regards
marlon :biggrin: :cool:

Hi
marlon
I have a very fundamental question please help me
Are electrons really close to structure less point charged particles?
Since I am not getting convinced from theory, is it the experiments that makes us believe so,then why is its size being revised year after year.
Are we missing something very fundamental?
Regards
Shankar
 
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  • #74
Narayanan.S said:
Hi
marlon
I have a very fundamental question please help me
Are electrons really close to structure less point charged particles?
Since I am not getting convinced from theory, is it the experiments that makes us believe so,then why is its size being revised year after year.
Are we missing something very fundamental?
Regards
Shankar

We have so far no experimental signs of size or structure of the electron; experimentally we can only deduce the UPPER LIMIT - and that limit changes as we reach higher and higher energies in our laboratories.

The upper limit of the electron radius is 10^-21 meters I think, thus we have not said that "the size of the electron IS 10^-21 meters", we have only said "IF the electron has size, then it is smaller than 10^-21meters".
 

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