# Errata for "Elementary Particle Physics: An Intuitive Introduction"

Below is a collection of errata identified for my textbook "Elementary Particle Physics: An Intuitive Introduction". If you find other errors in the book, please email me directly.

First Printing, 2019

p. 1: "principle" in the Classical Mechanics bullet point should be "principal". (Thanks Steve Wasserbaech!)

p. 1: "quanta" in the Quantum Mechanics bullet point should be "quantum". (Thanks Steve Wasserbaech!)

p. 4: Uranium decay is an alpha decay, which is not governed by the weak force. Carbon-14 decays via beta decay, and is mediated by the weak force, for example. (Thanks Steve Wasserbaech!)

p. 5: The view in Fig. 1.2 is more accurately to the southeast. (Thanks Steve Wasserbaech!)

p. 9: Before equation 1.13, these are the dimensions of hbar and c, not their units. (Thanks Steve Wasserbaech!)

Exercise 1.5, p. 11: The cosmic microwave background was observed by Andrew McKellar 20 years prior to Penzias and Wilson; see A.~McKellar, Molecular Lines from the Lowest States of Diatomic Molecules Composed of Atoms Probably Present in Interstellar Space,'' Publications of the Dominion Astrophysical Observatory Victoria, 7, 251 (1941)

Exercise 1.7 and figure 1.6, p. 13: The bubble chamber was actually superheated hydrogen and the Omega minus was produced in collision of a kaon and a proton, and not in the kaon decay. (Thanks Steve Wasserbaech!)

p. 18: Rotation matrices that act from the right should be transposed, even in index notation. (Thanks Steve Wasserbaech!)

p. 20: O(3,1) is the set of all matrices that leave the metric invariant, not "are". (Thanks Steve Wasserbaech!)

p. 21: "changing the relative velocity of the inertial frame by" should just be removed in the third sentence. (Thanks Steve Wasserbaech!)

p. 23: Regarding the mass shell: different masses define different "shells" of hyperbolas that are stacked in one another.

Eq. 2.61, p.27: the second partial derivative of time should be partial t^2, not partial^2 t. (Thanks Steve Wasserbaech!)

Eq. 2.120, p. 38: For consistency of the expression of Maxwell's equations, the mu index on the current four-vector should be lower, not upper, as is currently written.

Eq. 2.122, p. 38: The signs of the electric field components should be flipped for consistency.

Eq. 2.141, p.41: The sign in the conservation law should be positive, not negative. (Thanks Steve Wasserbaech for identifying inconsistencies in section 2.2.3!)

Eq. 2.142, p.41: The indices are not consistent throughout the chain of equalities. (Thanks Steve Wasserbaech!)

Exercise 2.9, p. 48: "Invariant mass" has not yet been defined. (Thanks Steve Wasserbaech!)

Eq. 3.53, p. 63: In the final line of this expression, the Pauli matrix that multiplies the sine factor should be \sigma_1, and not \sigma_2.

Eq. 3.67, p. 66: There should not be an overall minus sign on the right of this equation. Immediately below this equation, the description of why this state is referred to as "odd" is incorrect. It is odd because there is a relative minus sign under transposition of the two nucleons. Transposition is not a special unitary operation, and so a minus sign can arise. (Thanks Ely Eastman!)

Eqs. 4.50, 4.52, p. 90-91: After using the delta-function to integrate over the three-momentum p_2, the factor in the denominator should be \sqrt{|\vec p_1|^2 + m_1^2}, and not \sqrt{|\vec p_2|^2 + m_1^2}. (Thanks Krzysztof Kutak!)

Box 5.1, p. 127: In 2019, Fabiola Gianotti was reappointed to a second full term as CERN Director-General.

Footnote 16, p. 198: An idea similar to thrust was introduced long before Farhi's paper. The following reference described a procedure to split final states into two hemispheres such that the magnitude of momentum in each hemisphere is maximized:
S. Brandt, C. Peyrou, R. Sosnowski and A. Wroblewski, "The principal axis of jets -- an attempt to analyze high-energy collisions as two-body processes," Phys. Lett. 12, 57 (1964).

Starting at Eq. 8.23, p. 218, through derivations on page 219: The derivative of the spacetime-dependent non-Abelian matrix \mathbb{U} is not correct. It is true that \partial_\mu \mathbb{U} = \mathbb{U}\partial_\mu + (\partial_\mu \mathbb{U}), but the explicit derivative of the non-Abelian matrix is not found from such a simple application of the chain rule. This is because the derivative and the matrix in general do not commute with each other. The final result for the covariant derivative is unchanged, because the transformation of the vector potential and the action of the derivative on the matrix are explicitly designed to cancel one another. (Thanks Steve Wasserbaech!)

Box 8.1, p. 235: Gerardus t Hooft's name should have a space between "Gerardus" and "t".

Eq. 9.74, p.268: There is a missing factor of 2 in the alpha_s factor on the first line. (Thanks Yoni Kahn!)

Sec. 10.3, p. 288: It is stated that no experiment prior to 1957 had been done to test the parity properties of the weak interactions. This is not quite true; an experiment had been done in 1928 that could be interpreted as evidence for the polarization of electrons in nuclear scattering experiments, but wasn't identified as such for decades. The original papers are:
R. T. Cox, C. G. McIlwraith, and B. Kurrelmeyer, "Apparent Evidence of Polarization in a Beam of Beta-Rays," Proc Natl Acad Sci USA, 1928 Jul, 14(7): 544-549.
C. T. Chase, "A Test for Polarization in a Beam of Electrons by Scattering," Phys. Rev. 34, 1069, 1929.
A review article published shortly after the results of the Wu experiment that discusses these early results is:
L. Grodzins, "The History of Double Scattering of Electrons and Evidence for the Polarization of Beta Rays," Proc Natl Acad Sci USA, 1959 March, 45(3): 399-405.

Eq. 10.57, 10.58 p. 296: There should not be a minus sign on the right side of these expressions.

Eq. 11.141, p. 343: The expression in the inner square root should have a factor of the W mass squared times the top quark mass squared, not just the W mass times the square of the top quark mass.

App. B.3: This derivation of the Heisenberg equations of motion assumes that the total derivative of the expectation value is 0, but this need not be the case generally. Additionally, one should Taylor expand the left side of the equation to determine the total time derivative of the expectation value, and include it as well.