
Corrections to revised Second Edition (May 2014) of Student Friendly Quantum Field Theory
Note: 1st edition and 2^{nd} edition (original) users also need to check this 2^{nd} edition revision corrections page for additional corrections.

Sorted by Date Posted: This Page 
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Significant Corrections (may impact learning process)
Pg 
Chap 
Date Posted 
Significant Correction 
Reported by (blank = the author) 
373 
14 
June 26, 2015 
Prob. 3. Subscript C1 should be C2. 
Jimmy Snyder 
22 
2 
June 16, 2015 
Paragraph right before Sect 2.5.1. Replace entire paragraph/sentence with Note that, due to subtleties in the theory, nonrelativistic chart relationships are most easily, and best considered at this point, expressed in Cartesian coordinates, where x^{i} → X_{i} and p_{i} = p^{i}. 

30 
2 
June 16, 2015 
(242) and (243): On RHS, insert (Cartesian system, where p_{ j} = p^{j} = 3momentum) (Correction posted on June 12, 2015 for these equations has been removed and replaced with this one.) 

23 
2 
June 12, 2015 
Box 22. My purpose in this box was to give a derivation of (B22.3) that was much simpler than that in other books. There are some subtleties involved, but it is best not to worry about them until after you have mastered QFT. If at that time, you feel up to it, check out Box2_2_comments 

2526 
2 
June 12, 2015 
Line above (228) delete the minus sign after the equal sign. In (229), delete the minus sign before “i”. 

40 
3 
June 12, 2015 
Eq (33). The subscript “i” on p_{i} should be a superscript. 

42 
3 
June 12, 2015 
Eq (35). The subscript “i” on each p_{i} should be a superscript. 
Doug McKenzie 
146 
5 
June 12, 2015 
Eqs (545) and (546). The subscript “i” on each p_{i} should be a superscript. 
Doug McKenzie 
53 
3 
Apr 23, 2015 
There are some subtleties associated with (347) that merit more explanation in an Appendix. See Eq (347) subtleties, which includes the new Appendix E plus an elaboration. 
Michael Heiss 
68 
3 
Apr 23, 2015 
Top line: “Appendix B” should be Appendix C 
John Davidson 
147 
5 
Apr 21, 2015 
In (550), the RHS should be summed over r, as it is done (correctly) in Wholeness Chart 54, pg. 156. 
Ben Balmforth 
211 to 212 
7 
Apr 21, 2015 
It may be cumbersome keeping track of terms between (7110) and (7111). See From (7110) to (7111), which should help shortcut the tedium in doing so.^{} 
Kurt Huddleston 
82 
3 
Jan 17, 2015 
Prob 3, 1^{st} line: Replace “(327)” with (325)  
Michael Heiss 


Nov 25, 2014 
Solutions to Problems booklet now available. See problem solutions booklet 

421423 
16 
Oct 31, 2014 
Sect 16.4.6, Step #2 was not very clear. The revision, Sect 16.4.6 revision, should be considerably easier to understand. Note that Prob. 9 in this chapter is now deleted, as it related to material in Sect. 16.4.6 that was removed in this revision. 
Holger Teutsch 
485 
17 
Oct 3, 2014 
Prob. 3: The hint actually makes it more difficult. Do not express momentum as shown. Replace the hint with: “Use , a similar relation for particle #2, and the 3momentum balance equation [where total 3momentum is zero in the COM] to find . Divide this by the energy balance equation. Then add and subtract the energy balance equation from your result. “ 
Holger Teutsch 
431b 
16 
Sept 22, 2014 
Prob. 2 can be expressed more clearly with the following changes. 4^{th} line: change “=” to goes to . Same line: after “interactions” insert , since there is no g_{μν} in the scalar propagator . 
Holger Teutsch 
297 
11 
Sept 22, 2014 
Above (1140), add a footnote: The term “gauge covariant derivative” is different from, and should not be confused with, the “covariant derivative” of general relativity (and more generally, tensor analysis). It is unfortunate that similar nomenclature is used for the two cases. In the QFT we are studying, spacetime is flat (Minkowski space) and we use a Lorentz metric, so the covariant derivative of GR has Christoffel symbol of zero. This is made more confusing by the common dropping of the word “gauge” in QFT when referring to the gauge covariant derivative. You often have to glean the meaning from context. 
Thomas Fowler 
393 
15 
Sept 22, 2014 
(15107). The fermion propagators need to be sandwiched between the vertex gamma matrices and the k in the denominator needs to have a slash through it. See (15107) top row rev 
Holger Teutsch 
213c 
7 
Sept 18, 2014 
Prob. 11: At the end, before the period insert , if that commutator equals a constant 
Holger Teutsch 
233 
8 
Sept 18, 2014 
In (885) delete the underbracket at the end under the polarization vectors. Replace the paragraph following that thru (886) with pg 233 revision . 
Holger Teutsch 
329 
13 
Sept 16, 2014 
(1336). Exponent on e_{0} should be 4 not 2. Before that factor, insert a minus sign. 
Holger Teutsch 
180 
6 
Sept 15, 2014 
Prob. 13. Delete part ii). Upon further reflection, I believe the logic there is flawed. Part i) suffices to make the point. 
Holger Teutsch 
431a 
16 
Sept 9, 2014 
Last line: Change “and (1617)” to (1617), and (1628)  

431b 
16 
Sept 9, 2014 
End of 1^{st} paragraph: After the equal sign, insert “g^{2}” 

90 
4 
Aug 27, 2014 
Eq (427) was not explained clearly. On the RHS the integral is zero for p not = zero, but is V for p = 0. The spinor inner product in front of the integral is zero for p = 0. So, in any case, (427) is zero. 
Andrew Solomon 
132 
4 
Aug 21, 2014 
Prob. 14. D_{r}(p) should have a dagger on it. Also, just after that, insert in (429) 
Jimmy Snyder 
301 
11 
Aug 15, 2014 
Prob. 9. To make things a little easier to understand: In 2^{nd} line insert fermion before “field”. At end of last line, insert “Note that .” 

491509 
18 
July 21, 2014 
Chap. 18 has some spots that needed more extensive explanations, and in one section, had a missing constant through several equations. The revised pages can be found at Chap 18 revised pgs. Red font indicates changed material. Note that the former appendix added little and has been replaced with a new appendix, which compares and contrasts the NRQM background for the path integral approach as handled by different texts. 
Luc Longtin helped in innumerable ways on this. Holger Teutsch and Christian Maennel also contributed 
506 
18 
July 18, 2014 
Wholeness Chart 184, 1^{st} column, 3^{rd} row: Delete “(functionals)” 

34 
2 
July 16, 2014 
First line after (255). After “13.)”, insert Note from (255) that p^0 = gamma mc = E/c, where E is relativistic energy, and p^i = relativistic 3momentum. 
Jimmy Snyder 
68 
3 
July 16, 2014 
Sect 3.11.4, 3^{rd} paragraph, next to last line: before “eigenstates”, insert linearly independent 
Jimmy Snyder 
79 
3 
July 16, 2014 
(3148), 4^{th} (last) arrow, LHS: “x” should be x’ . Two places. 
Jimmy Snyder 
121 
4 
July 16, 2014 
(4146), second line: insert a minus sign after the 2^{nd} and 3^{rd} equal signs. 
Holger Teutsch 
82 
3 
July 8, 2014 
Prob. 3. Change “of negative unity” to is negative . One would have to assume a magnitude of unity, which would make sense if the value were positive. 

4950 
3 
June 23, 2014 
2nd line of text below (3.34), “(… Hermitian)”, should be (… Hermitian conjugate) . Same thing on pg. 50, just above (336). 
Jimmy Snyder 
288 
11 
June 19, 2014 
Paragraph including (118) and (119): delete this paragraph and the associated margin note. The sign on E^2 in (118) is wrong and thus (118) does not equal energy density. This paragraph was as aside (not part of the theory development) and was intended to be a simple and intuitive insight into the LHS of (118). Unfortunately, the issue is neither simple nor intuitive, but delving into it in proper depth would take us off on a tangent away from the focus of the chapter. 
Bill Foster 
118 
4 
June 12, 2014 
Step 2 and Step 3 near top of page: “commutators” should be anticommutators 
Sukruti Bansal 
503504 
18 
June 12, 2014 
An alternative derivation of the result in Sect. 18.9.2 may be easier to follow for some. See Alternative derivation for Sect. 18.9.2 
Luc Longtin 
504505 
18 
June 12, 2014 
Line above (1857), after comma at end of line, insert, where N = n + 1 = number of functions f_greek index , 

505 
18 
June 12, 2014 
(1859): On RHS, delete factor of sq root (2 pi hbar). Delete middle expression completely. (1860): Delete same factor in denominator. 

Minor Corrections (should not impact learning process)
Pg 
Chap 
Date Posted 
Minor Correction 
Reported by 
274 
10 
June 19, 2015 
In (108) and throughout this sections, change N to script N (representing number density per unit k. 

183 
7 
June 12, 2015 
Sect. 7.1.1, second line: “Gaussian” should be “HeavisideLorentz”. 

71 
3 
Apr 23, 2015 
Second line; should be "(interaction).” rather than “(interaction.)” 
John Davidson 
92 
4 
Apr 23, 2015 
Eq (436) under bracket: “(p)” should be just after "u_rdagger” not after gamma^0. 
John Davidson 
115 
4 
Apr 23, 2015 
Second line of section 4.9.2: move period in "… pseudovector).” inside parenthesis. 
John Davidson 
143 
5 
Apr 23, 2015 
3rd line below Fig. 52: In "del X A”, “X" needs to be reformatted. 
John Davidson 
149 
5 
Apr 23, 2015 
4th side note: 1^{st} “RQM” should be QFT 
John Davidson 
151 
5 
Apr 23, 2015 
Eq (569): ik_mu RHS has different font point sizes. 
John Davidson 
151 
5 
Apr 23, 2015 
Ref to original papers by Gupta and Bleuler should be added: K. Bleuler, Eine neue Methode zur Behandlung der longitudinalen und skalaren Photonen, Helvetica Phys. Acta 23 (1950), 567586. S.N. Gupta, Theory of longitudinal photons in quantum electrodynamics, Proc. Phys. Soc. Sect.A. 63 (1950), 681691. 
John Davidson 
184 
7 
Apr 23, 2015 
Eq (713): subscript “I” should be italic 
John Davidson 
185 
7 
Apr 23, 2015 
Eq. (715): Last underbracket superscript “I” should be 1. 
John Davidson 
222 
8 
Apr 23, 2015 
Eq (830), last row: under bracket should not include d^4k 
John Davidson 
256 
9 
Apr 23, 2015 
3^{rd} line: the x_i should be a subscript to the (…) term rather than inline with it. 
John Davidson 
323 
13 
Apr 23, 2015 
Eq (135): A(lambda, m) goes to  infinity rather than + infinity. 
John Davidson 
343 
14 
Apr 23, 2015 
line 2: change ”,to” to to, 
John Davidson 
429 
16 
Apr 23, 2015 
Last line of paragraph starting with “Rather…”, move period in ”.)” to outside of parenthesis. 
John Davidson 
493 
18 
Apr 23, 2015 
2^{nd} line after eq (1819), end of line: Period should be outside parenthesis. 
John Davidson 
211 
7 
Apr 21, 2015 
In (7110) first term in middle row, underbracket relation. The [A_{1}^{d},C_{3}^{c}] should be [A_{1}^{d},C_{3}^{c}]_{/+}, i.e., it should have minus/plus subscript as all other brackets in the equation do. 

325 
13 
Apr 21, 2015 
Gordon’s identity (1318) should have a box around it, as it is important in a number of places in subsequent chapters. But, it is not worth trying to memorize it. 

285a 
10 
Dec 24, 2014 
eq (1037): make “lim” symbol smaller font 

94 
4 
Nov 3, 2014 
Box 41: 4^{th} and 5^{th} eqs need to be aligned with others 

233 
8 
Nov 3, 2014 
6^{th} line up from bottom: insert hyphen after “4”. 

265 
9 
Oct 28, 2014 
Wholeness Chart 91: Top row, make arrow non italic. 

405 
16 
Oct 28, 2014 
Fig. 161: Correct spacing on figure title. (Only occurred in May 2014 revision, not earlier versions.) 

422 
16 
Oct 28, 2014 
Eq (1683): Delete one of the two periods at the end 

504 
18 
Oct 28, 2014 
Eq. (1855): In the exponent, delete spaces on either side of “delta t” 

506 
18 
Oct 28, 2014 
2nd line: delete “quantum field theory” 

236 
8 
Oct 6, 2014 
B. 4., end of 2nd line: Insert “r represents spin state for fermions and polarization state for photons, ( (493) and (494), pg. 111, may be of help below),” 
Thomas Fowler 
514 
19 
Oct 6, 2014 
B. 4., end of 2^{nd} line: Insert “r represents spin state for fermions and polarization state for photons, ( (493) and (494), pg. 111, may be of help below),” 
Thomas Fowler 
522 
index 
Oct 6, 2014 
After “Feynman rules, 224, 236, 513”, insert , 514 . 

485 
17 
Oct 3, 2014 
Prob 3, 2^{nd} line, 1^{st} word: Delete “s” at end of “particles”. 

235 
8 
Sept 18, 2014 
(889) should have a minus sign for the RHS 
Holger Teutsch 
28 
2 
Sept 17, 2014 
Wholeness Chart 24. Top RH box. All quantities between the bra and ket should be inside parentheses. 
Jimmy Snyder 
188 
7 
Sept 17, 2014 
Wholeness Chart 71. RH column for SP, HP, and IP.. All quantities between the bra and ket should be inside parentheses. 
Jimmy Snyder 
192 
7 
Sept 17, 2014 
(739). All quantities between the bra and ket should be inside parentheses. 
Jimmy Snyder 
372 
14 
Sept 17, 2014 
(1499). The e’s inside the bra and ket should be primed. 
Holger Teutsch 
431b 
16 
Sept 9, 2014 
3^{rd} line: change “[1 1 0 0]” to  [1 1 0 0]^{T}  

485 
17 
Sept 9, 2014 
Problem 1, 3^{rd} line: After “Find” insert the . 

179 
6 
Aug 27, 2014 
Probs. 1, 2, 4, and 6: Font for primes should be changed so they look more like primes than superscript commas. 
Holger Teutsch 
180 
6 
Aug 27, 2014 
Prob. 12, end of 3^{rd} line: gamma^mu should be larger font. 

133 
4 
Aug 21, 2014 
Prob. 25. Change period at end to question mark. 

82 
3 
Aug 21, 2014 
Prob. 12, 5^{th} line: after “different from” insert (orthogonal to) 
Jimmy Snyder 
5354 
3 
Aug 20, 2014 
Eqs (351), (352), (353) the omegas in the exponents should all be omega_k. 
Jimmy Snyder 
506 
18 
July 18, 2014 
Wholeness Chart 184, 1st column, 3^{rd} row: change “Dynamic” to Dynamical . 2 places. 

506 
18 
July 18, 2014 
Wholeness Chart 184, 1^{st} row: change “phidot” to phi,_mu 

507 
18 
July 18, 2014 
Wholeness Chart 184, 1st column, 3^{rd} row: change “Dynamic” to Dynamical 

507 
18 
July 18, 2014 
Wholeness Chart 184, 2^{nd} part “Quantum Theories”, 3^{rd} column, 4^{th} row: change “phidot” to phi,_mu 

32 
2 
July 16, 2014 
The double bracket on the RHS of (247) should be a single bracket. 
Jimmy Snyder 
46 
3 
July 16, 2014 
3^{rd} line after (324): subscript “ k’ “ should have prime not apostrophe. 
Andrew Solomon 
64 
3 
July 16, 2014 
Sect. 3.8.3, 2^{nd} line: delete extra space before “and” 

65 
3 
July 16, 2014 
Chart 31; Fermions column, 3^{rd} box under heading: delete “the”. 
Jimmy Snyder 
67 
3 
July 16, 2014 
5^{th} line below (3112). Change“(not eigen)” to (not necessarily eigen) 
Jimmy Snyder 
69 
3 
July 16, 2014 
Wholeness Chart 33, 3^{rd} row under headings: Before “frequency” insert angular . 
Jimmy Snyder 
74 
3 
July 16, 2014 
Next to last line on pg. The subscript 0 on k should be smaller font. 
Jimmy Snyder 
75 
3 
July 16, 2014 
In the text below (3136), Insert a space between “see” and “(32)”. 
Jimmy Snyder 
75 
3 
July 16, 2014 
paragraph to the right of Figure 35, 2^{nd} line of text. Change “still c.c.w.” to still counter clockwise [ccw], as in Fig. 34 
Jimmy Snyder 
79 
3 
July 16, 2014 
From (3149) to (3152) three different forms are used to symbolize the differential element in 3D position space, dx, d^{3}x, and d^{3}x. These should all be the same for consistency. Take your pick. 
Jimmy Snyder 
255 
9 
July 16, 2014 
(93) 2^{nd} line: parenthesis before N should be non italic. at end of last line: add )d^{4}x_{1} d^{4}x_{2 }d^{4}x_{3} 

57 
3 
July 9, 2014 
Above (365), after “examples,”, insert where k not equal k’, 
Jimmy Snyder 
57 
3 
July 9, 2014 
Paragraph above Sect. 3.5 headin, 1st line, “of LHS” should be “of the LHS”. 
Jimmy Snyder 
58 
3 
July 9, 2014 
In eqn (372), the underbracket is redundant given the text that follows it. 
Jimmy Snyder 
61 
3 
July 9, 2014 
In the 2nd line on the page, there is an extra period after i.e., 
Jimmy Snyder 
61 
3 
July 9, 2014 
Sect. 3.6.6, last paragraph, next to last line: “of this book”. should say of this book's publication 
Jimmy Snyder 
61 
3 
July 9, 2014 
The title of section 3.7.1 should have a comma between “Currents” and “Operators”. 
Jimmy Snyder 
233 
8 
July 2, 2014 
(885) and (886): “delta^ (k k′)” should be delta^(4) (k k′) 

6 
1 
June 23, 2014 
6^{th} line: change “can not” to cannot 
Jimmy Snyder 
15 
2 
June 23, 2014 
3^{rd} line: change “M^0” to (MeV)^0, i.e., M=0 
Jimmy Snyder 
22 
2 
June 23, 2014 
Box 21, next to last paragraph, 2^{nd} line: delete extra space and period before closing parenthesis. 
Jimmy Snyder 
23 
2 
June 23, 2014 
3rd line of item 6 at the top of the page. "Box" should be Box 2.2 . 
Jimmy Snyder 
26 
2 
June 23, 2014 
eqn (2.29), the S after the last equal sign is separated from the open bracket. 
Jimmy Snyder 
26 
2 
June 23, 2014 
eqn (2.31) the size of the brackets is asymmetric. 
Jimmy Snyder 
2628 
2 
June 23, 2014 
eq (234): the superscript S is the wrong typeface, 2 places; eqn (2.37): ditto, 4 places; also in other places 
Jimmy Snyder 
27 
2 
June 23, 2014 
Box 2.3, 3rd paragraph. Inspection is sufficient to reach these conclusions if H is hermitian, which it is. 
Jimmy Snyder 
27 
2 
June 23, 2014 
Box 2.3, 4th line from the bottom. change "eigenstate state" to eigenstate 
Jimmy Snyder 
32 
2 
June 23, 2014 
2^{nd} line: “Preface” should not be capitalized 
Jimmy Snyder 
32 
2 
June 23, 2014 
above (2.45), there should be a space between “See” and “Sect” and a period after “Sect” 
Jimmy Snyder 
36 
2 
June 23, 2014 
Prob. 4: First sentence at end, delete one period. Part c), remove period after first alpha subscript. 
Jimmy Snyder 
43 
3 
June 23, 2014 
2nd line below (3.9), the dagger is placed too far to the upper right of B_n. 
Jimmy Snyder 
44 
3 
June 23, 2014 
Below (3.13) and also text below (3.15)(44), the dagger on B is misplaced. Three instances. 
Jimmy Snyder 
82 
3 
June 23, 2014 
Prob. 2: the dagger on B is misplaced; Prob. 3: dagger on B_k is misplaced 
Jimmy Snyder 
219 
8 
June 23, 2014 
Box 8.1, last paragraph, 1st sentence: delete extra period 
Jimmy Snyder 
36 
2 
June 12, 2014 
Prob. 4, 1^{st} line: superscript “alpha beta” on “g” should be smaller font size. 

107 
4 
June 12, 2014 
Box 43: Equation numbers need to be aligned. 

122 
4 
June 12, 2014 
exponents should be larger font size. 

127 
4 
June 12, 2014 
Conclusion #2: Remove underlining on whole sentence. Leave underlining on “Conclusion #2” 

148 
5 
June 12, 2014 
(554) and (556): “a” and “b” should be larger font. 

150 
5 
June 12, 2014 
(568): k^2 in denominator should be larger font size. 

156 
5 
June 12, 2014 
Wholeness Chart 54, 2^{nd} row of cells from bottom: exponent “ikx” should be smaller font size. 

265 
9 
June 12, 2014 
Prob. 1, at end: Change period to question mark. 

277 
10 
June 12, 2014 
1^{st} margin note: Delete space between “usual” and “type” 

305 
12 
June 12, 2014 
6^{th} and 7^{th} bullets: alpha and pi should be smaller size. 

305 
12 
June 12, 2014 
Under (121): in ket, remove space after “f”. 

316 
12 
June 12, 2014 
Paragraph above Fig. 124: “Figure” should be “Fig.” 

350 
14 
June 12, 2014 
Wholeness Chart 141: After heading “Short cut route”, “Sect. 0” should be Sect. 14.2.3 

403 
16 
June 12, 2014 
top line: lower case “phi” should be upper case “Phi”. 2 places. 

419 
16 
June 12, 2014 
(1672) and (1672): (2 pi)^3 in denominators should be larger font size. 3 places 

504 
18 
June 12, 2014 
(1852): subscript “a” should be alpha . 2 places. Also “dx” too small, 3 places. 
