A Particle Physics Reference and Study Guide

James Emery

Last Edit 1/15/2015

Contents

1 Preface 4

2 Radioactivity: α, β, γ Radiation 4

3 Fields 4

4 A Survey of the Standard Model 5

5 Rutherford: the Discovery of the Nucleus 5

6 Gauge Theory 5

7 Lie Groups and Lie Algebras 6

8 Blackbody Radiation: Planck’s Constant 8

9 The Classical Roots of Quantum Field Theory 8

10 The Lagrangian and Hamiltonian 8

11 The Photoelectric Effect: the Photon 9

12 Electricity and Magnetism → Electromagnetism 9

13 Chadwick: The Discovery of the Neutron 9

14 The Dirac Theory of the Electron, the Positron. 10

1

15 Symmetry and Group Theory 10

16 Gauge Symmetry 10

17 Supersymmetry 10

18 Noether’s Theorem 10

19 Nonconservation of Parity 11

20 Force as Particle Exchange, Yukawa and the Meson 11

21 Quantum Field Theory 11

22 Quantum Electrodynamics (QED), Renormalization: Feyn-mann, Swinger, and Tomanga. 12

23 The Eightfold Way, Quarks and Gluons: Murray Gell-Mannand Finnegan’s Wake 12

24 The Electro-Weak Theory: Weinberg, Glashow, Salam 12

25 The Fine Structure Constant 12

26 Feynman Diagrams 14

27 Virtual Photons 14

28 Vacuum Fluctuations 14

29 The Higgs Boson 14

30 Supersymmetry 14

31 Kaluza-Klein Theory 15

32 QED 15

33 The Standard Model 15

34 Cross Section 15

2

35 The J/ψ Particle 15

36 Leon Lederman and the God Particle 16

37 Spin 16

38 Maxwell-Boltzmann Statistics 17

39 Fermi-Dirac Statistics 18

40 Bose-Einstein Statistics 18

41 Leptons, Quarks 19

42 Hadrons, Baryons 19

43 The History of Particle Physics 19

44 Links 19

45 Charge 19

46 Properties of the Particles 20

47 Yang-Mills Fields 20

48 Baryons 20

49 String Theory 2049.1 Heterotic String . . . . . . . . . . . . . . . . . . . . . . . . . . 21

50 Abraham Pais and the History of 20th Century Physics 21

51 CERN 21

52 CERN Atlas 21

53 CERN CMS 22

54 The Muon 23

3

55 The Tau 23

56 Meson Particles 23

57 Hadrons 24

58 Bibliography 24

1 Preface

These are notes and references for particle physics. I read the book byWilliams, Nuclear and Particle Physics, some yeats ago. Some timeafter that I realized that the similar book by Kane, Modern ElementaryParticle Physics, is a better book, and should be used, temporarily at least,as a primary beginning serious book on particle physics. However, Williamsalso is a good reference, because it does present many examples related toexperiments. For Quantum field Theory, perhaps one should use StephenWeinberg’s book (3 volumes), The Quantum Theory of Fields. Thebibliography contains several items quite useful for learning particle physics.

2 Radioactivity: α, β, γ Radiation

In the early days of radioactivity, three forms of radiation were known. Theα particle turned out to be the nucleus of the Helium atom. The β particleturned out to be an electron and came from beta decay in the nucleus. Thisbeta decay also required the emission of a massless particle called the neu-trino, although it is still not certain that the neutrino is really completelywithout mass. The theory of beta decay is due to Enrico Fermi, while Pauliintroduced the neutrino. γ radiation is electromagnetic radiation, and thusconsists of high energy photons. Radiation is really just a general emissionfrom a center. The term comes from the word radial. Thus radiation hasmany forms.

3 Fields

The basic constituents of the universe are fields and field theories. Particlesare waves in the fields, which are localized and observable as objects during

4

interactions. See Carroll.

4 A Survey of the Standard Model

see Modern Elementary Particle Physics, Chapter 1.

5 Rutherford: the Discovery of the Nucleus

Ernest Rutherford was born August 30, 1871, in Nelson, New Zealand. Hewas for a time at McGill University in Toronto. He returned to England andjoined the University of Manchester, and then Cambridge University. He iscredited with the discovery of the nucleus of the atom.

The Geiger-Marsden Gold foil experiment(also called the Rutherford ex-periment) was an experiment done by Hans Geiger and Ernest Marsden in1909, under the direction of Ernest Rutherford, at the Physical Laboratoriesof the University of Manchester. He was also the director of the Cavendishlaboratory for many years. He died on October 19, 1937 after falling out ofa tree.

A beam of alpha particles, generated by the radioactive decay of radium,was directed normally onto a sheet of very thin gold foil. The gold foil wassurrounded by a circular sheet of zinc sulfide (ZnS) which was used as anindicator. The ZnS sheet would light up when hit with alpha particles. Underthe prevailing plum pudding model, the alpha particles should all have beendeflected by, at most, a few degrees. However they observed that a verysmall percentage of particles were deflected through angles much larger than90 degrees. From this observation Rutherford was able to observe and deductthe central structure of the atom.

6 Gauge Theory

In physics, a gauge theory is a type of field theory in which the Lagrangianis invariant under a continuous group of local transformations.

The term gauge refers to redundant degrees of freedom in the Lagrangian.The transformations between possible gauges, called gauge transformations,form a Lie group which is referred to as the symmetry group or the gaugegroup of the theory. Associated with any Lie group is the Lie algebra of group

5

generators. For each group generator there necessarily arises a correspondingvector field called the gauge field. Gauge fields are included in the Lagrangianto ensure its invariance under the local group transformations (called gaugeinvariance). When such a theory is quantized, the quanta of the gauge fieldsare called gauge bosons. If the symmetry group is non-commutative, thegauge theory is referred to as non-abelian, the usual example being the Yang-Mills theory.

Gauge theories are important as the successful field theories explain-ing the dynamics of elementary particles. Quantum electrodynamics is anabelian gauge theory with the symmetry group U(1) and has one gaugefield, the electromagnetic field, with the photon being the gauge boson. TheStandard Model is a non-abelian gauge theory with the symmetry groupU(1)SU(2)SU(3) and has a total of twelve gauge bosons: the photon, threeweak bosons and eight gluons.

Many powerful theories in physics are described by Lagrangians whichare invariant under some symmetry transformation groups. When they areinvariant under a transformation identically performed at every point in thespace in which the physical processes occur, they are said to have a globalsymmetry. The requirement of local symmetry, the cornerstone of gauge the-ories, is a stricter constraint. In fact, a global symmetry is just a local sym-metry whose group’s parameters are fixed in space-time. Gauge symmetriescan be viewed as analogues of the equivalence principle of general relativityin which each point in space-time is allowed a choice of local reference (co-ordinate) frame. Both symmetries reflect a redundancy in the description ofa system.

Historically, these ideas were first stated in the context of classical electro-magnetism and later in general relativity. However, the modern importanceof gauge symmetries appeared first in the relativistic quantum mechanics ofelectrons quantum electrodynamics, elaborated on below. Today, gauge the-ories are useful in condensed matter, nuclear and high energy physics amongother subfields.

7 Lie Groups and Lie Algebras

A set of transformations is called a Lie (pronounced Lee) group if the setforms a group and is defined by a parameter so that the transformation iscontinuous. In general Lie group transformations have matrix representa-

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tions.An n dimensional square complex matrix, a matrix whose elements are

complex numbers, is called a unitary matrix if its conjugate transpose isits inverse. So if U∗ is obtained from U by swapping rows with columnsand taking the complex conjugate of each element, it is called the conjugatetranspose. So a matrix is unitary if

UU∗ = U∗U = I,

where I is the identity matrix. Thus U∗ is the inverse of U by definition. Aunitary real matrix is called an orthogonal matrix. It represents a rotation.The row vectors and the column vectors of an orthogonal matrix are orthog-onal, the row and column vectors have unit length, and the transformationpreserves length.

So a proper matrix in the the group of 2 dimensional orthogonal matriceshas the form

[

cos(θ) − sin(θ)sin(θ) cos(θ)

]

,

and has determinant

D = cos2(θ) + sin2(θ) = 1.

So[

cos(θ) − sin(θ)sin(θ) cos(θ)

] [

xy

]

=

[

cos(θ)x− sin(θ)ysin(θ)x+ cos(θ)y

]

is a positive rotation by θ.Notice that as θ varies continuously, the rotation varies continuously, so

this is a Lie group. The n dimensional orthogonal group is called O(n). Nowthe matrix

[

cos(θ) sin(θ)sin(θ) − cos(θ)

]

,

is also orthoginal but has determinant -1, and does not preserve orienta-tion.

The group of orthogonal matrices that each have determinant one is calledthe special orthogonal group and is written SO(n).

The n dimensional unitary group is similarly written U(n), and the specialn dimensional unitary group with determinant 1, is written SU(n)

7

8 Blackbody Radiation: Planck’s Constant

In considering the black body radiation confined to a box, if one consideredeach possible electromagnetic wave that satisfies the boundary conditions,and if each such wave was considered in equilibrium with an oscillator ofenergy 1/2kT , in accordance to the equipartition of energy theorem of sta-tistical mechanics, then the energy density would go to ∞ as the wave lengthdecreased. This paradox was called the Ultraviolet Catastrophe. Plancksolved the problem by requiring that the energy states were discrete ratherthan continuous, thus getting finite energy. He introduced the Planck con-stant h defining the allowed energies.

9 The Classical Roots of Quantum Field The-

ory

The classical underpinnings of modern quantum field theory are treated inthe book by A. O. Barut Electrodynamics and Classical Theory ofFields and Particles, Dover reprint, 1980.

10 The Lagrangian and Hamiltonian

Lagranges equations and Hamilton’s equations are equivalent to Newton’sequation of motion in classical mechanics, namely Newton’s second law.

F = ma.

http://www.stem2.org/je/mechanics.pdf

In classical mechanics the hamiltonianH is equal to the sum of the kineticand potential energies.

As you recall in the Schrodinger equation for the hydrogen atom, opera-tors in the equation can be identified with the kinetic and potential energiesso that this equation is the analog of Newton’s second law. See chapter oneof Kane for example.

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http://www.stem2.org/je/hydrogenatom.pdf

11 The Photoelectric Effect: the Photon

If an electroscope is given a negative charge, and a metal plate on top ofthe electroscope is exposed to intense light then the electroscope begins todischarge and the deflected metal leaves begin to come together. Further ifthis plate is placed in a vacuum tube, and a potential established between theplate and a second electrode, that the discharge can be stopped. Thus theelectrons are being given energy by the light. Further this required stoppingvoltage depends on the frequency of light. Einstein formulated a theory of thephotoelectric effect that proposed that light energy is in the form of discreteenergy particles called photons, and the energy of a photon is given as hν,where ν is the light frequency.

12 Electricity and Magnetism → Electromag-

netism

According to Maxwell’s theory and Relativity, whether a field is consideredan electric field or a magnetic field depends on the coordinate system. Thusthe magnetic field and the electric field are part of the same thing. HenceElectricity and Magnetism becomes Electromagnetism. Later electromag-netism and the weak force are united as the electro-weak force.

13 Chadwick: The Discovery of the Neutron

In 1932 Chadwick discovered the neutron in the nucleus of an atom. It iscalled the neutron because it has no electric charge. Chadwick was awardedthe Nobel prize for this discovery. Being uncharged, and thus able to pene-trate the charged nucleus, the neutron became an important tool in subse-quent particle research.

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14 The Dirac Theory of the Electron, the

Positron.

Dirac put forth an equation, known as the Dirac equation, to create a quan-tum theory of the electron, and to create quantum electrodynamics. In solv-ing his equation for the electron, he found a second solution with oppositecharge and thus predicted the existence of the positron, which was laterdiscovered in a particle accelerator experiment.

15 Symmetry and Group Theory

See

http://www.stem2.org/je/groups.pdf

16 Gauge Symmetry

Aitchison I. J. R, Hey A. J. G. Gauge Theories in Particle Physics

17 Supersymmetry

See the book Supersymmetry by Gordon Kane, and learn about Squarksand Photinos.

Sylvester James Gates supersymmetry, first book on supersymmetry WithM. T. Grisaru, M. Rocek and W. Siegel, Gates coauthored Superspace, orOne thousand and one lessons in supersymmetry, (1984) the firstcomprehensive book on supersymmetry.

18 Noether’s Theorem

Certain symmetries imply conserved quantities. Some books that I own, haveinteresting materials on Noether’s theorem and with proofs.

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Analytical Mechanics by Louis N Hand and Janet D Finch Cambridge,1998. Chapter 5 is Noether’s Theorem and Hamiltonian Dynamics.

Quantum Electrodynamics by Sokolov and others.

A book on Noether’s theorem and the calculus of variations is FrederickW Byron and Robert Fuller, Mathematics of Classical and QuantumMechanics Dover, 1969.

19 Nonconservation of Parity

20 Force as Particle Exchange, Yukawa and

the Meson

In studying the neutron-proton scattering, where the state of the two par-ticles, as a function of the distance between them, Fig 9.13 Williams, is asuperposition of the two individual states, it was found from experimentsthat the scattering cross section of the nuclear force decreases because of thelimits on the momentum transfer, but that at closer distances the scatter-ing cross section increases greatly. This was explained by postulating theexistence of a Bosonic exchange particle with a bosonic potential of shortexponential range.

The exchange of a Boson with mass m gives a potential varying as

exp(−mcr/h)/r.

Simplified argument: Page 176 Williams. Yakawa predicted the existence ofthe meson as this bosonic exchange particle, and further predicted that thisparticle could be found in high energy collisions. The meson was found in1950.

21 Quantum Field Theory

Quantum Mechanics and Relativity were fused into Quantum Field Theoryand predicted the existence of antimatter, which was observed around 1930.in the Forward to Kane’s book on Supersymmetry Edward Witten has an

11

interesting remark, ” Quantum Field Theory is very difficult to understand;trying to understand it has occupied the attention of many leading physicistsfor many generations.”

22 Quantum Electrodynamics (QED), Renor-

malization: Feynmann, Swinger, and Tomanga.

See the small book by Feynman called QED.

23 The Eightfold Way, Quarks and Gluons:

Murray Gell-Mann and Finnegan’s Wake

The six quarks are: Up, Down, Strange, Charmed, Top, and Bottom. TheNeutron is uncharged, hence a DUD (Down,Up, Down). The Proton then isUDU. Since the Proton has charge plus 1, the U quark has charge plus 2/3 andthe D quark charge −1/3. So the charge of the Proton is 2/3−1/3+2/3 = 1,whereas the charge of the Neutron is −1/3 + 2/3 − 1/3 = 0.

24 The Electro-Weak Theory: Weinberg, Glashow,

Salam

For the history of this discovery see the book by Glashow.

25 The Fine Structure Constant

The fine structure constant first appeared in the work of Arnold Sommerfeldof 1916, where an attempt was made to explain the fine structure of theatomic spectral lines by using relativity. The first physical definition of thefine structure constant was as follows. The fine structure constant is theratio of the electron velocity in the first Bohr orbit to the velocity of light(Eisberg, pp 116-134). For a more advanced and modern definition, see theWikipedia article saved as fine structure constant.pdf. In the Gaussian CGS

12

system (Eisberg, pp 116-134)

α =e2

(h/(2π)c=

1

137

In the CGS system, Coulomb’s Law is

F =q1q2r2

.

See also physics5.xls. In the MKS system

α =e2

4πε0hc.

e = 1.60 × 10−19C.

h = 6.63 × 10−34J · S = 6.63 × 10−34N ·M · S.

h =h

2π

ε0 = 8.85 × 10−12C2

N ·M2.

c = 3 × 108M/S.

In the MKS system, Coulomb’s Law is

F =q1q2

4πε0r2.

Calculating with these constants, we get a dimensionless value

1

α= 137.52

The constant α plays a roll for example in the force caused by photonparticle exchange between electrons, and in the related Feynmann diagrams.

13

26 Feynman Diagrams

27 Virtual Photons

28 Vacuum Fluctuations

29 The Higgs Boson

The Higgs boson is a hypothetical elementary particle predicted by the Stan-dard Model (SM) of particle physics. It belongs to a class of subatomicparticles known as bosons, characterized by an integer value of their spinquantum number. The Higgs field is a quantum field with a non-zero valuethat fills all of space, and explains why fundamental particles such as quarksand electrons have mass. The Higgs boson is an excitation of the Higgs fieldabove its ground state. The observation of the Higgs boson using the LHCwas announced by CERN in 2012. See Carroll, The Particle at the Endof the Universe, 2012.

The existence of the Higgs boson is predicted by the Standard Model toexplain how spontaneous breaking of electroweak symmetry (the Higgs mech-anism) takes place in nature, which in turn explains why other elementaryparticles have mass. Its discovery would further validate the Standard Modelas essentially correct, as it is the only elementary particle predicted by theStandard Model that has not yet been observed in particle physics experi-ments.[2] The Standard Model completely fixes the properties of the Higgsboson, except for its mass. It is expected to have no spin and no electric orcolor charge, and it interacts with other particles through weak interactionand Yukawa interactions. Alternative sources of the Higgs mechanism thatdo not need the Higgs boson are also possible and would be considered if theexistence of the Higgs boson were ruled out. They are known as Higgslessmodels.

30 Supersymmetry

See the books by Kane.

14

31 Kaluza-Klein Theory

Kaluza-Klein theory (KK theory) is a model that seeks to unify the twofundamental forces of gravitation and electromagnetism. The theory wasfirst published in 1921. It was proposed by the mathematician TheodorKaluza who extended general relativity to a five-dimensional spacetime. Theresulting equations can be separated into further sets of equations, one ofwhich is equivalent to the Einstein field equations, another set equivalent toMaxwell’s equations for the electromagnetic field and the final part an extrascalar field now termed the ”radion”.

32 QED

Quantum Electrodynamics is a Quantum Fields Theory for the electroweakforce.

33 The Standard Model

See the survey in Kane.

34 Cross Section

See the section on scattering cross section in quantum.tex.

35 The J/ψ Particle

The J/ψ is a subatomic particle, a flavor-neutral meson consisting of a charmquark and a charm antiquark. Mesons formed by a bound state of a charmquark and a charm anti-quark are generally known as ”charmonium”. TheJ/ψ is the first excited state of charmonium (i.e., the form of the char-monium with the second-smallest rest mass). The J/ψ has a rest mass of3, 096.9MeV/c2, and a mean lifetime of 7.2× 1021 s. This lifetime was abouta thousand[1] times longer than expected.

Its discovery was made independently by two research groups, one at theStanford Linear Accelerator Center, headed by Burton Richter, and one at

15

the Brookhaven National Laboratory, headed by Samuel Ting at MIT. Theydiscovered they had actually found the same particle, and both announcedtheir discoveries on 11 November 1974. The importance of this discovery ishighlighted by the fact that the subsequent, rapid changes in high-energyphysics at the time have become collectively known as the ”November Revo-lution”. Richter and Ting were rewarded for their shared discovery with the1976 Nobel Prize in Physics.

36 Leon Lederman and the God Particle

Leon Lederman wrote a book on the search for the Higgs boson called theGod Particle. Many physicists are unhappy with that name; the ”nuts”have grabbed onto it. Lederman who is a bit of a jokester, said that he hadoriginally titled the book The God Damned Particle but the publishers madehim change it.

Among Lederman’s achievements are the discovery of the muon neutrinoin 1962 and the bottom quark in 1977. These helped establish his reputationas among the top particle physicists.

In 1977, a group of physicists led by Leon Lederman announced that aparticle with a mass of about 6.0 GeV was being produced by the Fermilabparticle accelerator. The particle’s initial name was the greek letter Upsilon(Υ). After taking further data, the group discovered that this particle didnot actually exist, and the ”discovery” was named ”Oops-Leon” as a pun onthe original name and Lederman’s first name.

In 1988, Lederman received the Nobel Prize for Physics along with MelvinSchwartz and Jack Steinberger ”for the neutrino beam method and thedemonstration of the doublet structure of the leptons through the discov-ery of the muon neutrino.”

Lederman is also famous for taking prospective students to the circus andfiring them out of a cannon in order to determine if they are ”High Caliber.”

37 Spin

In quantum mechanics and particle physics, spin is a fundamental charac-teristic property of elementary particles, composite particles (hadrons), andatomic nuclei.

16

All elementary particles of a given kind have the same spin quantum num-ber, an important part of the quantum state of a particle. When combinedwith the spin-statistics theorem, the spin of electrons results in the Pauliexclusion principle, which in turn underlies the periodic table of chemicalelements. The spin direction (also called spin for short) of a particle is animportant intrinsic degree of freedom.

Wolfgang Pauli was the first to propose the concept of spin, but he did notname it. In 1925, Ralph Kronig, George Uhlenbeck, and Samuel Goudsmitsuggested a physical interpretation of particles spinning around their ownaxis. The mathematical theory was worked out in depth by Pauli in 1927.When Paul Dirac derived his relativistic quantum mechanics in 1928, electronspin was an essential part of it.

There are two types of angular momentum in quantum mechanics: Or-bital angular momentum, which is a generalization of angular momentum inclassical mechanics (L = r × p), and spin, which has no analogue in classi-cal mechanics. Since spin is a type of angular momentum, it has the samedimensions: J · s in SI units. In practice, however, SI units are never usedto describe spin: instead, it is written as a multiple of the reduced Planckconstant h. In natural units, the h is omitted, so spin is written as a unit-less number. The spin quantum numbers are always unitless numbers bydefinition.

38 Maxwell-Boltzmann Statistics

In statistical mechanics, MaxwellBoltzmann statistics describes the statisti-cal distribution of material particles over various energy states in thermalequilibrium, when the temperature is high enough and density is low enoughto render quantum effects negligible.

Ni

N=

gi

eεi−µ/kT=gie

−εi/kT

Z,

whereNi is the number of particles in state i.εi is the energy of the ith state.gi is the degeneracy of states.µ is the chemical potentialκ is Boltzman’s constant

17

T is absolute temperatureN is the total number of particlesZ is the partition function

Z =∑

i

gie−εi/kT .

(Wikipedia Maxwell-Boltzmann statistics)

39 Fermi-Dirac Statistics

Fermions are particles which are indistinguishable and obey the Pauli exclu-sion principle, i.e., no more than one particle may occupy the same quantumstate at the same time. Fermions have half-integral spin. Statistical ther-modynamics is used to describe the behavior of large numbers of particles.Number of particles in state i,

ni =gi

eεi−µ/kT + 1

where gi is the degeneracy of states. gi is the dimension of the eigenspacefor the given energy eigenvalue. µ is the chemical potential as introduced byWillard Gibbs, as an example a fermi level in a semiconductor. For a singleorbital the distribution would be

ni =1

eεi−µ/kT + 1

and takes the value between 0 and 1. That is, the orbital is occupied by atmost 1 particle by the exclusion principle. Spin 1/2 particles, antisymetricwave functions. See Kittel Thermal Physics, Margenau and Murphy for oldtreatment. Distribution appeared in separate papers by Fermi and Dirac in1926.

(Wikipedia fermi-dirac statistics) Fermi-Dirac statistics apply to fermions(particles that obey the Pauli exclusion principle.)

40 Bose-Einstein Statistics

Determines the statistical distribution of identical indistinguishable bosonsover the energy states in thermal equilibrium. After Satyendra Nath Bose and

18

his statistical theory of photons. Bose-Einstein Statistics applies to Bosons.Bosons, unlike fermions, are not subject to the Pauli exclusion principle: anunlimited number of particles may occupy the same state at the same time.Number of particles in state i,

ni =gi

eεi−µ/kT− 1

(Wikipedia Bose=Einstein statistics) Bose-Einstein and Fermi-Dirac distri-butions differ only in the sign placed on the 1 in the denominator. Bose-Einstein Condensate is a consequence and is related.

In the classical limit of low temperatures all three distributions agree.Feynman in volume III of his lectures has a section on a Boson gas derived

from his Feynman diagram type of arguments with amplitudes and so on.

41 Leptons, Quarks

Leptons and quarks are fermions, and make up the non-field particles.

42 Hadrons, Baryons

Hadrons are the particles composed of quarks. Baryons are the hadronscomposed of three quarks such as the neutron and the proton. Originally thename referred to the heavy particles, bary meaning weight.

43 The History of Particle Physics

44 Links

http://www.particleadventure.org/other/history/index.html

http://pprc.qmul.ac.uk/~lloyd/epp/lectures/History.pdf

saved as: briefhistoryparticlephysics.pdf

45 Charge

electric charge, weak charge, and color or strong charge.

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46 Properties of the Particles

Leptons and quarks are fermions, Fermi-Dirac statistics, spin 1/2, Paulyexclusion principle. The Leptons are the electron e, muon µ, tau τ andassociated neutrinos νeνµντ . 3 families (e, νe), (µ, νµ)(τ, ντ ). And the quarks(up,down,top,bottom,strange, charmed), three families They are fermions.

The Bosons are spin 1 particles, do not satisfy the Pauli exclusion princi-ple. They are the force particles. Bose-Dirac statistics, photons, gluons, Wand Z.

Hadrons are heavy particles made up of quarks. These include the proton,the neutron, and the mesons.

47 Yang-Mills Fields

48 Baryons

A baryon is a composite subatomic particle made up of three quarks (asdistinct from mesons, which comprise one quark and one antiquark). Baryonsand mesons belong to the hadron family, which are the quark-based particles.The name ”baryon” comes from the Greek word for ”heavy”, because, atthe time of their naming, most known elementary particles had lower massesthan the baryons. Hadros (Greek) means thick or heavy, leptos (greek) meanssmall.

49 String Theory

A popular exposition of string theory is The Elegant Universe by BrianGreene. String theory attemps to create a theory of everything, both thesmal scale world of Quantum Mechanics and the large scale world of GeneralRelativity. To do this space is a multiple dimension manifold, with thosedimensions beyond the fourth being ”curled up” dimensions at a very smallscale, so small that many claim could never be observed by experiment.Particles become one dimensional loops called strings. See also the popularbook on String Theory by Michio Kaku Hyperspace. Kaku also has aserious book on string theory – Introduction to Superstrings and M-Theory –, but when I mentioned this book to Brian Greene he turned up

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his nose.

49.1 Heterotic String

A closed string that has two types of vibration clockwise and anticlockwise.From greek heterosis ”hybred vigor”.

50 Abraham Pais and the History of 20th

Century Physics

Pais wrote several books on the history of twentieth century physics, whichinclude much mathematical and technical detail. See the bibliography.

51 CERN

The European Organization for Nuclear Research (French: Organisation eu-ropenne pour la recherche nucleaire), known as CERN or Cern is an interna-tional organization whose purpose is to operate the world’s largest particlephysics laboratory, in the northwest suburbs of Geneva on the FrancoSwissborder (46d14m3sN 6d3m19sE). Established in 1954, the organization has20 European member states.

The term CERN is also used to refer to the laboratory, which employsjust under 2,400 full-time employees, 1,500 part time employees, and hostssome 10,000 visiting scientists and engineers, representing 608 universitiesand research facilities and 113 nationalities.

52 CERN Atlas

ATLAS is a particle physics experiment at the Large Hadron Collider (LHC)at CERN. The ATLAS detector is searching for new discoveries in the head-on collisions of protons of extraordinarily high energy. ATLAS will learnabout the basic forces that have shaped our Universe since the beginning oftime and that will determine its fate. Among the possible unknowns are theorigin of mass, extra dimensions of space, unification of fundamental forces,and evidence for dark matter candidates in the Universe.

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ATLAS detector Size: 46 m long, 25 m high and 25 m wide. The ATLASdetector is the largest volume particle detector ever constructed. Weight:7000 metric tons, Design: barrel plus end caps, Location: Meyrin, Switzer-land.

ATLAS (A Toroidal LHC Apparatus) is one of the seven particle detectorexperiments (ALICE, ATLAS, CMS, TOTEM, LHCb, LHCf and MoEDAL)constructed at the Large Hadron Collider (LHC), a new particle acceleratorat the European Organization for Nuclear Research (CERN) in Switzerland.ATLAS is 45 metres long and 25 metres in diameter, weighing about 7,000tons. The project was led for about 15 years- since its creation- by Peter Jenniand since 2009 by Fabiola Gianotti. The huge collaboration involves roughly3,000 physicists at 175 institutions in 38 countries.[1][2] The construction wasready and detected its first single beam events on 10 September 2008.[3] Thedata taking was then interrupted for over a year due to LHC magnet quenchincident. On November 23rd 2009, the first proton-proton collisions occurredat the LHC at- a relatively low- injection energy of 450 GeV per beam. Thesecollisions were successfully registered in ATLAS, which was been logging dataever since, as the LHC energy has been increasing: 900 GeV per beam atthe end of 2009, 3,500 GeV for the whole 2010 and 2011 and finally 4,000GeV per beam in 2012 before the long shutdown which will double its energy.The experiment is designed to take advantage of the unprecedented energyavailable and observe phenomena that involve highly massive particles whichwere not observable using earlier lower-energy accelerators and might shedlight on new theories of particle physics beyond the Standard Model.

53 CERN CMS

The Compact Muon Solenoid (CMS) experiment is one of two large general-purpose particle physics detectors built on the proton-proton Large HadronCollider (LHC) at CERN in Switzerland and France. Approximately 3,600people, representing 183 scientific institutes and 38 countries, form the CMScollaboration who built and now operate the detector.[1] It is located in anunderground cavern at Cessy in France, just across the border from Geneva.

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54 The Muon

The muon from the Greek letter µ is an elementary particle similar to theelectron, with unitary negative electric charge (-1) and a spin of 1/2. To-gether with the electron, the tau τ , and the three neutrinos (ν), it is classifiedas a lepton. As is the case with other leptons, the muon is not believed tohave any sub-structure at all (i.e., is not thought to be composed of anysimpler particles). the muon is a fermion.

55 The Tau

The tau is a fermion.

56 Meson Particles

In particle physics, mesons are hadronic subatomic particles composed ofone quark and one antiquark, bound together by the strong interaction. Be-cause mesons are composed of sub-particles, they have a physical size, witha radius roughly one femtometre, which is about 2/3 the size of a proton orneutron. All mesons are unstable, with the longest-lived lasting for only afew hundredths of a microsecond. Charged mesons decay (sometimes throughintermediate particles) to form electrons and neutrinos. Uncharged mesonsmay decay to photons.

Mesons are not produced by radioactive decay, but appear in nature onlyas short-lived products of very high-energy interactions in matter, betweenparticles made of quarks. In cosmic ray interactions, for example, such par-ticles are ordinary protons and neutrons. Mesons are also frequently pro-duced artificially in high-energy particle accelerators that collide protons,anti-protons, or other particles containing quarks.

In nature, the importance of lighter mesons is that they are the associatedquantum-field particles that transmit the nuclear force, in the same way thatphotons are the particles that transmit the electromagnetic force. The higherenergy (more massive) mesons were created momentarily in the Big Bang butare not thought to play a role in nature today. However, such particles areregularly created in experiments, in order to understand the nature of theheavier types of quark which compose the heavier mesons.

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Mesons are part of the hadron particle family, defined simply as par-ticles composed of quarks. The other members of the hadron family arethe baryons: subatomic particles composed of three quarks rather than two.Some experiments show evidence of tetraquarks”exotic” mesons made of twoquarks and two antiquarks; the particle physics community regards their ex-istence as unlikely, although possible.[1] Since quarks have a spin of 1?2, thedifference in quark-number between mesons and baryons results in mesonsbeing bosons while baryons are fermions.

57 Hadrons

Hadrons are elementary particles composed of quarks.

58 Bibliography

[1] Williams, W. S. C. Nuclear and Particle Physics, 1991, Oxford. Seepage 176 for a simple explanation of exchange forces given by Yukawa.

[2] Kane, Gordon Modern Elementary Particle Physics, 1993, Addison-Wesley

[3] Kane, Gordon Supersymmetry, There is a glossary defining particlephysics terms. 2000, Perseus.

[4] Glashow, Sheldon Interactions, 1993, Warner Books. Contains an Ap-pendix giving a chronology of major particle physics discoveries.

[5] Eisberg Robert Martin Fundamentals of Modern Physics, John Wi-ley, 1967.

[6] Hand Louis N, Finch Janet D Analytical Mechanics Cambridge, 1998.

[7]Sokolov A.A., Ternov I. M., Zhukovskii V. Ch., Borisov A. V. QuantumElectrodynamics MIR Publishers Moscow, 1988.

[8]Pickering Andrew Constructing Quarks: A Sociological History of

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Particle Physics The historian of modern sciences has to come to termswith the fact that the scientists have got there first...” (more) Key Phrases:charmonium model, baryonium states, unified electroweak gauge theories,November Revolution, Big Bang,

[9]Aitchison I. J. R, Hey A. J. G. Gauge Theories in Particle PhysicsSecond Edition, Adam Hilger, 1989.

[10]Kenyon I. R. Elementary Particle Physics Routledge and Kegan PaulLtd, 1987.

[11] Weinberg, Steven The Quantum Theory of Fields, 3 volumes.

[12] Feynmann, Richard QED

[13] Kaku, Michio, Hyperspace

[14] Louis N Hand and Janet D Finch, Analytical Mechanics Cambridge,1998. See Chapter 5 for Noether’s Theorem and Hamiltonian Dynamics.

[15] Sokolov Quantum Electrodynamics.

[16] Frederick W Byron and Robert Fuller, Mathematics of Classical andQuantum Mechanics Dover, 1969. A source for the Calculus of Variations

and Noether’s Theorem.

[17] Kaku, Michio, Introduction to Superstrings and M-Theory, Springer,1999, 587 pages, Linda Hall Library.

[19] Pais, Abraham, Subtle is the Lord: The Science and Life of Al-bert Einstein, Clarendon Press/Oxford University Press, 1982.

[20] Pais, Abraham, Inward Bound: Of matter and forces in the phys-ical world, Clarendon Press/Oxford University Press, 1982.

[21] Pais, Abraham, Niels Bohr’s Times: In physics, philosophy, andpolity, Clarendon Press/Oxford University Press, 1991.

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[22]Carroll, Sean M., The Particle at the End of the Universe: Howthe Hunt for the Higgs Boson Leads Us to the Edge of A NewWorld, Dutton, 2012, 539.721 C236, Johnson County, Midcontinent.

[23] Close Frank, Marten Michael, Sutton Christine, The Particle Explo-sion, Oxford University Press, 1987. This book contains a history and outline

of particle physics, great historical pictures, descriptions of the big machines

and detectors, a table of particles, and many images of particle tracks

[24] Gates Sylvester James, M. T. Grisaru, M. Rocek and W. Siegel, Super-space, or One thousand and one lessons in supersymmetry, (1984).The first comprehensive book on supersymmetry.

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