Christine Dissertation Comments

Documentation

* Thesis v1

Color code for answers to reviewer questions:

  • Green -- I agree, changes to analysis/documentations implemented.
  • Lime -- I agree, but the item hasn't been done yet. (Open item.)
  • Red -- I disagree, changes to analysis/documentation is not implemented.
  • Teal -- I agree, but we don't think any change to analysis/documentation is needed.
  • Blue-- discussion needed. (Open item.)

Sign-off from committee members

Name Status
Robin Not done.
John Not done.
Max Not done.

Comments

V4

Robin

Intro: Not mandatory but I would reword this whole first intro bit to make it active. "In this dissertation I describe...."

I'd prefer to leave it as is.

| 52 - 55: I don't understand the 2nd half of this sentence, "Breakthroughs such as Planck's formula for blackbody radiation, Einstein's explanation of the photoelectric effect, and the discovery of the Compton effect indicated the quantization of electromagnetic radiation into individual photons."

Changed to, "Breakthroughs such as Planck's formula for blackbody radiation, Einstein's explanation of the photoelectric effect, and the discovery of the Compton effect indicated that electromagnetic radiation, classically understood to exhibit wave-like properties, was made up of particles called photons."

| 151 - 152: In the sentence, "The Heisenberg uncertainty principle, $\Delta x \Delta p \geq \bar{h}/2$ , tells us that the range of the force is inversely proportional to the mass of the mediator," change "the force" to "the electromagnetic force."

I changed it to "a force" to make it more general.

| 307: GR is sometimes capitalized... up to you

I decided to leave it uncapitalized.

| 679: "The thickness of the HCAL, in radiation lengths, varies from 10–15 lambda_I, depending on eta." Mention what lambda_I is.

I changed corrected radiation lengths to say nuclear interaction lengths.

| 708 -709: "The magnet and yoke allow for good momentum resolution and triggering, while the latter also acts as a hadron absorber for muon ID." Why/how (good resolution and triggering)?

The geometry of the high-field magnet and its flux-return yoke provides strong muon bending power and confines a large portion of the backgrounds to the endcap muon detectors closest to the IP, thus enabling good momentum resolution and triggering. The flux-return yoke also acts as a hadron absorber for muon ID.

| 978 -980: "These algorithms should be infrared and collinear (IRC) safe and should provide a repeatable method for combining constituent particles." What does this mean? Put quotes? Add a reference.

These algorithms should be infrared and collinear (IRC) safe, meaning they should be insensitive to the emission of arbitrarily soft (low energy) or collinear particles~\cite{ca}. Additionally, jet clustering algorithms should provide a repeatable method for combining constituent particles.

| 1077: Where is PFCHS defined?

This term has already been used in the event reconstruction section, and it has now been defined more explicitly.

| 1084: what is "truth level"? (define). I guess you sort of define it in the next sentences but you don't say you are defining it. Maybe "Truth level matching is when Signal jets are matched to known generator-level particles..."

Changed both instances of "truth-level" to generator-level.

Table 7.2: can't anything else fit on this page?

Unfortunately, this table cannot fit on the previous page and all chapters start a new page.

V0: Intro through top-tagging

Max

Christine,

Here are my comments on your theory chapter. You need to produce a line-numbered version of your thesis so we can more easily make comments. Probably good to have different version #'s as well from now on. In general, there are quite a few vague statements that need to be made precise.

Max

specific comments:

describe QFT

Added a subsection giving a brief introduction to QFT.

remove slayer comment.

Done.

dirac equation?

Added it to QFT intro and referenced it in the SM particles subsection.

why is the electron stable?

Of the charged leptons, only the electron is stable. This is due to the fact that it is the lightest charged particle, and its decay would violate total electric charge, a quantity conserved in all particle interactions.

gauge theory? Local gauge invariance and the problem of mass?

Added some information to the QFT section, but a lot of elaboration was added to the Higgs/EWSB section.

table 2.2 which coupling are you referring to for the weak interaction? G_F or alpha_W. ? Should clarify here/in text.

alpha_W - clarified in the table, already written in the text.

is the strong decay 10^-23 or 10^-25? text contradicts table

Changed to 10^-23 - 10^-24 s, as stated in Bettini.

why do the couplings run with q^2 ?

Expanded the explanation past the first sentence, "As with the coupling constants of the other fundamental forces, $\alpha$ is dependent on the four-momentum transfer, or $Q^2$, that occurs in the interaction:

\alpha(Q^2)=\frac{\alpha(\mu^2)}{1-z_f\frac{\alpha(\mu^2)}{3\pi}ln(|Q|^2/\mu^2)},

where $\mu$ is a scale constant and $z_f$ is the sum of the squares of the charges of the fermions with mass < $Q$ \cite{Bettini}. As the energy $Q$ reaches a given fermion mass threshold, particle-antiparticle pairs of that type are resolved and contribute to the value of $\alpha$. While $Q$ denotes the energy of the interaction, $Q^2$ is the relevant Lorentz-invariant quantity.

move the discussion of the top quark decay earlier to weak decay discussion.

Done. Switched strong and weak decay discussions so that hadronization was already defined and to have a better flow from weak discussion to Higgs discussion.

baryon # conservation?

After, "Protons ($uud$) and neutrons ($udd$) are the two baryons most commonly found in nature," added, "While free neutrons are unstable, protons, on the other hand, are stable. This is due to the fact that proton decay would violate baryon number ($N$(baryons)-$N$(antibaryons)), a quantity conserved in all known interactions. Experiments testing for the most likely proton decay scenario, in which the proton decays into a positron and a neutral $\pi$ meson, have excluded proton lifetimes below $\sim 10^{34}$ years, $10^{24}$ times the age of the universe \cite{Bettini}.".

why does the q-q energy increase as you pull them apart? What distance? Jets only occur if the energy is large enough. What is the minimum energy? What are the constituents of the jets (light flavor jets - primarily pions, with...) heavy flavor... boosted top...

As quarks are pulled apart in high energy collisions, the color field energy density between them remains constant, causing the associated energy to increase proportionally with distance. When the energy between a pair of quarks becomes larger than the mass energy of a quark anti-quark pair, it becomes energetically favorable for the original quark pair to radiate a gluon, which in turn produces the new quark-antiquark pair \cite{Bettini}. As more and more quarks are produced, they group into hadrons. This process is known as hadronization and results in a cone of particles known as a jet. Typically, jets formed by light quarks contain mostly $\pi$ and $K$ mesons, while the hadronization of b quarks will create B mesons. It is through the observation of jets that quarks are identified in particle detectors.

I go into more detail about jets in the event reconstruction section.

Discuss Higgs before gravity

Done.

give more precise values for W, Z masses

Done.

Is lepton flavor conserved in NC processes? CC?

After, "Quark flavor, or type, is conserved in NC, but not CC processes," added, "Both types of weak processes conserve total lepton number ($N$(leptons)-$N$(antileptons)), as the SM does not allow any violation of this quantity \cite{Bettini}. Additionally, all processes predicted by the Standard Model conserve partial lepton number, e.g. electron flavor number."

gravity: many orders of magnitude -- how many ??

Changed to "at least 33 orders of magnitude"

gravity: mention dark matter?

This is discussed in the "Standard Model Limitations" section. The "Dark Matter and Dark Energy" bullet have been edited to explicitly mention gravity, "From cosmological observations, we know that ordinary baryonic matter makes up only 4--5\% of the mass-energy content of the universe. Measurements of galaxy rotation curves and galaxy cluster masses indicate that a type of massive, non-electromagnetically-interacting type of matter, called dark matter, makes up about 25\% of the universe. Additionally, it has been observed that the universe is expanding at an accelerating rate. If the universe was only made up of matter, gravity should have caused its rate of expansion to decrease. Measurements of the universal expansion rate indicate that the rest of the universe is in fact composed of dark energy, a density of negative pressure causing this accelerated expansion \cite{Bettini}. While the Standard Model provides a good description of baryonic matter, it does not account for dark matter or dark energy - 95\% of the total content of the universe!"

Higgs/EWSB:

what "high energies" ? mediators are essentially massless? M_W and M_Z -> 0?

This section has been greatly elaborated.

Give Higgs mass here.

Done.

BSM

Hierarchy problem: I don't think you've described fine tuning correctly. Since you've written a quadrature sum, the bare mass term can't cancel the second term.

Actually, the bare mass term is a negative number, taken from the Higgs potential. I have now explicitly stated that it is negative.

RS1 - here you mention couple unification but you didn't mention it in 2.2.1

Removed the last two sentences from this paragraph as there is already sufficient motivation for this theory.

I don't think you have the correct references for RS. try: http://inspirehep.net/search?ln=en&p=find+a+randall+and+topcite++1000%2B&of=hb&action_search=Search&sf=earliestdate&so=d

I reference the papers I used in writing this part of my thesis. Jim Dolen also used them in his thesis.

not worth defining FCNC and EWPT since you only use them in this paragraph.

Okay

what is a zero-mode?

The SM particles can then be described as the zero-modes of these five dimensional fields, analogous to the lowest order normal mode of a harmonic oscillator.

give reference for extended RS model

Changed "In the extended RS1 model" to "In this extended RS1 model." The citation has already been placed at the end of the next sentence, and it was the last reference cited.

Fig 2.2.1: for what sqrt{s} is this plot valid? Should specify! You haven't defined cross section so far.

Changed sentence to, "Its production cross section, proportional to the probability it will be produced, is shown on the left in Fig. \ref{RSG_xsbr}, assuming proton-proton collisions with a 14 TeV center-of-mass energy."

Justin

https://www.dropbox.com/s/2blfh71fka2se4f/McLeanThesis_introThroughTopTagging.pdf?dl=0

p. 4: Define spin

In my new section introducing QFT, I say "spin (a type of intrinsic angular momentum)"

p. 14: what about extra constraints that have to be imposed to enhance decays to top? Z' has to be in top color model, e.g. to suppress decays to leptons or light quarks

Specified "leptophobic topcolor Z' gauge bosons."

Change whiteboard picture in appendix to keynote diagram

Done.

Reyer

3.2.6. Muon System:

  • p.38
  • Typo: “combination of GE1/1”

Fixed.

  • Typo: low pT < 25 GeV not 25

Fixed.

  • p.39
  • I don’t think GEMs use CF4 anymore, we run with Ar/CO2 at I think. We’re forced to be environmentally friendly. Not sure if we will use CF4 in the full GE1/1 or not.

Fixed.

  • p.41
  • Typo: Missing absolute sign around eta

Fixed.

  • Fig. 3.2.17 There are 24 readout sectors

Fixed.

GEM Appendix:

  • p49:
  • Probably worth explaining what the threshold being set to zero is. Cam would throw a fit about calling this noise smile Maybe say pedestal or something.

New sentence, "First, I set the VFAT2 readout threshold, the value above which charge on the chip is read out as a signal event. For a given VFAT2, I started by setting the threshold to 0, i.e. the value at which any amount of charge on the strips is recorded as signal."

I'm going to keep it as noise to be consistent with Thomas's thesis, which I'm citing.

  • “Minimum noise chosen” I think this just ended up being first threshold value (starting from high end) that gives zero noise, and then we mask outlier channels identified by the s-curve

I don't think we ever quite see zero noise.

  • p51:
  • Typo?: Quotes around “s-curve” are ugly

Fixed.

  • Maybe talk about the OptoHybrid a bit, the scan modules it runs and the tools it has (for example, the charge calibration circuit)

I think that's beyond the scope of this appendix. It's in the reference.

  • Typo: “at scurve”-> an s-curve

Fixed.

  • Fig A.2.3 Maybe label this as VFAT2

Fixed.

  • Do you want to describe the current calibration method for findings trims? The plot you showed in Fig. A.2.4 comes from a slightly different method than what we did last summer. I don’t think it will be terribly interesting though.

I'll leave it as is, since I didn't work on the new method and the basic principle is the same.

  • Maybe include some explanation of why you want the read-out channels to have equal response to input charge, so the s-curves seem more important.

Added a sentence at the end. "Indeed, a consistent response is seen across all channels, especially at 50\% efficiency. Therefore, a muon with a given energy will cause a consistent response across the whole chip."

EYETS:

  • Nice pictures!

-- ChristineAngelaMcLean - 2018-01-19

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