The Standard Model

The current state of the classification of elementary particles is the Standard Model. It describes the strong, weak, and electromagnetic fundamental forces, using mediating gauge bosons. The species of gauge bosons are the gluons, W⁻ and W⁺ and Z bosons, and the photons. The model also contains 24 fundamental particles, which are the constituents of matter. Finally, it predicts the existence of a type of boson known as the Higgs boson, which has yet to be discovered.

I. Reading exercises:

Exercise1. Read and memorize using the dictionary:

constituents, occur, collision, particle accelerators, quarks, leptons, interacting particles, subatomic particles, composite particles, radiative and scattering processes, wave-particle duality, convention, fermions, vector bosons, scalar bosons, composite particles, neutrino mass, deviation, adhere to reductionism, conglomerate, culminate, rendering, bewilder, deprecate, mediate, predict

Exercise 2. Answer the questions:

1. What does Particle Physics study?

2. Why is Particle Physics also called high energy physics?

3. What is modern particle physics research focused on?

4. How many species of elementary particles does the standard model have?

Exercise 3. Match the left part with the right:

1. Modern particle physics research is focused on	a. on the philosophy of science.
2. Strictly speaking, the term particle is a misnomer	b. by a quantum field theory called the Standard Model.
3. All particles and their interactions observed to date can almost be described entirely	c. because the dynamics of particle physics are governed by quantum mechanics.
4. Particle physics has had a large impact	d. subatomic particles, which have less structure than atoms.

Exercise 4. Open brackets using the right words:

The idea that all matter is (created/composed) of elementary particles dates to at least the 6^th century BC. The particle theory of light was also (nominated/proposed) by Alhazen, Avicenna, Gassendi and Newton.

The Speaking Module

II. Speaking exercises:

Exercise 1. Describe matter; collision; lepton; gauge boson using the suggested words and expressions:

mater perceptible to the senses; the substance composing bodies; includes any entity; when at rest; possessing mass example: Matter – the substance composing bodies perceptible to the senses; includes any entity possessing mass when at rest.

collision the close approach of two or more bodies; an interaction resulting from; particles or systems of particles; and confined to a relatively short time interval; changes abruptly; during which the motion of at least one of the particles or systems

lepton smaller than the proton mass; a fermion having a mass; electromagnetic and gravitational fields; leptons interact with

gauge boson such as the protons and gluons; a massless spin particle; by gauge invariance in a gauge theory; whose existence is required

Exercise 2. Ask questions to the given answers:

1. Question: ____________________________________ ?

Answer: The Standard Model describes the strong, weak, and electromagnetic fundamental forces, using mediating gauge bosons.

2. Question: ____________________________________ ?

Answer: In the 19^th century, John Dalton, through his work on stoichiometry, concluded that each element of nature was composed of a single, unique type of particle.

3. Question: ____________________________________ ?

Answer: Throughout the 1950s and 1960s, a bewildering variety of particles were found in scattering experiments.

The Writing Module

III. Writing exercises:

Exercise 1. Complete the sentences with the suggested words: less; composite; on; such as; as well as; by; of:

Modern particle physics research is focused ______ subatomic particles, which have ______ structure than atoms. These include atomic constituents ______ electrons, protons, and neutrons (protons and neutrons are actually ______ particles, made up ______ quarks), particles produced ______ radiative and scattering processes, such as photons, neutrinos, and muons, ______ a wide range of exotic particles.

Exercise 2. Fill in the table with words from the text. Group the synonyms:

branch	accelerant
occur	component
detect	notice
collision	unite
accelerator	maintain
constituent	subdivision
wide	find
exhibit	broad
describe	variety
observe	display
species	depict
combine	happen
impact	influence
defend	clash

Exercise 3. Compose a story on one of the topics (up to 100 words):

“Standard Model”

“The species of gauge bosons”

“The fundamental particles of nature”

Lesson 7

The Reading Module

Read the text: Theoretical Particle Physics

Theoretical particle physics attempts to develop the models, theoretical framework, and mathematical tools to understand current experiments and make predictions for future experiments. There are several major efforts in theoretical particle physics today and each includes a range of different activities. The efforts in each area are interrelated. There are five most important states in particle theory: one of the major activities in theoretical particle physics is the attempt to better understand the standard model and its tests. By extracting the parameters of the standard model from experiments with less uncertainty, this work probes the limits of the standard model and therefore expands our understanding of nature. These efforts are made challenging by the difficult nature of calculating many quantities in quantum chromodynamics. Some theorists making these efforts refer to themselves as phenomenologists and may use the tools of quantum field theory and effective field theory. Others make use of lattice field theory and call themselves lattice theorists.

Another major effort is in model building where model builders develop ideas for what physics may lie beyond the standard model (at higher energies or smaller distances). This work is often motivated by the hierarchy problem and is constrained by existing experimental data. It may involve work on supersymmetry, alternatives to the Higgs mechanism, extra spatial dimensions (such as the Randall-Sundrum models), Preon theory, combinations of these, or other ideas.

A third major effort in theoretical particle physics is string theory. String theorists attempt to construct a unified description of quantum mechanics and general relativity by building a theory based on small strings, and branes rather than particles. If the theory is successful, it may be considered a "Theory of Everything".

There are also other areas of work in theoretical particle physics ranging from particle cosmology to loop quantum gravity.

This division of efforts in particle physics is reflected in the names of categories on the preprint archive: hep-th (theory), hep-ph (phenomenology), hep-ex (experiments), hep-lat (lattice gauge theory).

Public policy

Experimental results in particle physics are often obtained using enormous particle accelerators which are very expensive and require large amounts of government funding. Because of this, particle physics research involves issues of public policy.

The future

Particle physicists internationally agree on the most important goals of particle physics research in the near and intermediate future. The overarching goal, which is pursued in several distinct ways, is to find and understand what physics may lie beyond the standard model. There are several powerful experimental reasons to expect new physics, including dark matter and neutrino mass. There are also theoretical hints that this new physics should be found at accessible energy scales. Most importantly, though, there may be unexpected and unpredicted surprises which will give us the most opportunity to learn about nature.

Much of the efforts to find this new physics are focused on new collider experiments. A (relatively) near term goal is the completion of the Large Hadron Collider (LHC) in 2008 which will continue the search for the Higgs boson, supersymmetric particles, and other new physics. An intermediate goal is the construction of the International Linear Collider (ILC) which will complement the LHC by allowing more precise measurements of the properties of newly found particles. A decision for the technology of the ILC has been taken in August 2004, but the site has still to be agreed upon.

Additionally, there are important non-collider experiments which also attempt to find and understand physics beyond the standard model. One important non-collider effort is the determination of the neutrino masses since these masses may arise from neutrinos mixing with very heavy particles. In addition, cosmological observations provide many useful constraints on the dark matter, although it may be impossible to determine the exact nature of the dark matter without the colliders. Finally, lower bounds on the very long lifetime of the proton put constraints on Grand Unification Theories at energy scales much higher than collider experiments will be able to probe any time soon.

I. Reading exercises:

Exercise1. Read and memorize using the dictionary:

framework, interrelate, extract, uncertainty, challenge, lattice theorists, constrain, special dimensions, string theory, unified description, loop quantum gravity, overarching goal, pursue, accessible, collider experiments, complement, constraint

Exercise 2. Answer the questions:

1. What does theoretical particle physics attempt to develop?

2. How many states are there in particle theory?

3. What do string theorists attempt to construct?

4. What are much of the efforts focused on?

Exercise 3. Match the left part with the right:

1. There are several major efforts in theoretical particle physics today and	a. is constrained by existing experimental data.
2. The efforts in each area	b. by the difficult nature of calculating many quantities in quantum chromodynamics.
3. The efforts are made challenging	c. are interrelated.
4. This work is often motivated by the hierarchy problem and	d. each includes a range of different activities.

Exercise 4. Open brackets using the right words:

Another major effort is in model building where model builders (evolve/develop) ideas for what physics may lie beyond the (standard/classical) model at (lower/higher) energies or (smaller/larger) distances.

The Speaking Module

II. Speaking exercises:

Exercise 1. Describe theory; standard model; quantum chromodynamics; particle accelerator; collider using the suggested words and expressions:

theory a certain class of phenomena; an attempt to explain; by deducing them; of other phenomena; as necessary consequences; regarded as more primitive; and less in need of explanation example: Theory – an attempt to explain a certain class of phenomena by deducing them as necessary consequences of other phenomena regarded as more primitive and less in need of explanation.

standard model of the interaction of elementary particles; the modern theory; and quantum chromodynamics; comprising the Weinberg-Salam theory

quantum chromodynamics the strong interactions; a gauge theory of; among quarks

particle accelerator electrically charged atomic or subatomic particles; which accelerates; such as electrons, protons or ions; to high energies

collider accelerator; colliding beam; a particle accelerator; high energy particles; in which two beams of; are allowed to collide head-on; high center-of-mass energies; resulting in

Exercise 2. Ask questions to the given answers:

1. Question: ____________________________________ ?

Answer: Cosmological observations provide many useful constraints on the dark matter.

2. Question: ____________________________________ ?

Answer: Particle physicists internationally agree on the most important goals of particle physics research in the near and intermediate future.

3. Question: ____________________________________ ?

Answer: There are several powerful experimental reasons to expect new physics, including dark matter and neutrino mass.

The Writing Module

III. Writing exercises:

Exercise 1. Complete the sentences with the suggested words: to find; are; beyond; non-collider:

Additionally, there ______ important ______ experiments which also attempt ______ and understand physics ______ the standard model.

Exercise 2. Fill in the table with words from the text. Group the synonyms:

attempt	implement
develop	forecast
tool	exertion
prediction	region
major	enlarge
effort	labour
different	sequence
area	strive
understand	unite
expand	main
idea	various
work	comprehend
involve	thought
string	evolve
unify	contain

Exercise 3. Compose a story on one of the topics (up to 100 words):

“String theory”

“The Large Hadron Collider”

“The International Linear Collider”

Lesson 8

The Reading Module