BSM Journal Club

The particle theory graduate student journal club meets once a week to discuss topics of interest in Beyond the Standard Model phenomenology and model building. Topics roughly alternate between review articles and new papers.

Image from Lepton Photon 2013
via Mihoko Nojiri

Mondays, 1:30pm -- 3:00pm
Physical Sciences Building, Room 470
Contact:

Archives of past semesters (from the Flip Tanedo era):

BSM Club Fall 2009
BSM Club Spring 2010
BSM Club Fall 2010
BSM Club Spring 2011 (geometry)
BSM Club Fall 2011 (colliders)
BSM Club Spring 2012
BSM Club Fall 2012
BSM Club Spring 2013

Archives of past semesters (modern era):

BSM Club Fall 2013

Spring 2014 Schedule

Topics marked (R) are review talks where some previous reading is recommended but not necessary. Otherwise topics are "current papers" and everyone is expected to have read the main paper in advance.

Spring 2014 Abstracts

• Talk rescheduled to April 14, Nic Rey-Le Lorier (27 Jan 14).
  Abstract.
  Reference:
• Massive Neutrinos, Jeff Asaf Dror (3 Feb 14).
  The existence of non-zero neutrino masses implies that the Standard Model needs to be extended in some way. The fact that neutrinos are much lighter than the other particles in the Standard Model constrains the different ways neutrinos can get a mass naturally. Nevertheless, incorporating their mass can be done in several ways including simple Dirac mass terms, different see-saw mechanisms, and loop-induced masses. In this talk I will discuss the fundamentals of neutrino masses with a focus on the typical see-saw mechanism and its extensions.
  Reference: hep-ph/0001264, TASI 2013 Neutrino Lectures, Lecture Notes by the speaker
• Partially Composite Z and W, Jack Collins (10 Feb 14).
  We will review the 2011 paper by Csaba, John and Yuri, arXiv:1106.3074, where they played around with some explicit model building to make the W and Z bosons (partially) composite states of some strongly coupled supersymmetric gauge theory, described in terms of Seiberg Duality. The attempted focus of the talk will be on what lessons we can learn about using Seiberg Duality for supersymmetric model building, and I will try and avoid going into too much detail regarding the formalities and details as far as I am able.
  Reference: hep-ph/1106.3074
• Composite Higgs and extra-dimensions, Mario Martone (24 Feb 14).
  An interesting possibility to resolve the hierarchy problem is to have the Higgs arise as a pseudo-Goldstone boson. Such models go under the name of Composite Higgs models. Yet exact calculations for many observables are hard to carry out as they involve strong dynamics above the spontaneous symmetry breaking scale. A way around this is to explicitly write down a weakly coupled UV completion of these theories which allows exact computations.
  Reference: hep-ph/0412089, hep-ph/0306259
• A Higgslike Dilaton, Mathieu Cliche (3 Mar 14).
  I will review a model in which the Higgs boson is the Goldstone boson of scale invariance, called the dilaton. I will first discuss the couplings of the dilaton to the standard model particles and show how this can be a phenomenologically acceptable model. I will then discuss the fine tuning required to make the mass of the dilaton equal to the Higgs mass.
  Reference: arxiv:1209.3299
• Non-perturbative effects and cosmological constant, Sina Bahrami (10 Mar 14).
  After a brief introduction to the cosmological constant problem, we will review a fairly recent idea which attributes the smallness of cosmological constant to possible non-perturbative effects in the standard model. We will use operator expansion product as a tool during the talk, so prior familiarity is recommended.
  Reference: arxiv:1305.5191, Collins' Renormalization book, Notes on OPE
• Gong Show! (17 Mar 14).
  Reference:
• RS I Models, Nic Rey-Le Lorier (24 Mar 14).
  The Randall-Sundrum I models present a solution to the hierarchy problem by introducing a fifth, strongly warped dimension. We will review the theoretical and phenomenological content of these type of models and discuss their interpretation in light of the AdS/CFT correspondance (A Exam talk).
  Reference: hep-ph/9905221, hep-ph/0308036, arXiv:1207.3827
• Two-time Theories, Wee Hao Ng (7 Apr 14).
  Just as two-timing is generally frowned upon in real life, having two time dimensions in quantum field theory is often a recipe for disaster, in the form of more bad ghosts than your grandfather's gauge symmetries can Ecto-contain. However, it has been shown that this disaster can be averted by gauging the symplectic symmetry of the theory. An interesting result is that different gauge choices give rise to very different looking one-time quantum systems that are dual to one another, hence offering a tantalising new look at the general concept of dualities. In this talk, we focus mostly on humble quantum mechanical systems, with a sprinkle of field theoretic applications towards the end.
  Reference: hep-th/9803188, hep-th/9804028v3, Extra Dimensions in Space and Time (Bars and Terning)
• Little Higgs Models, Nic Rey-Le Lorier (14 Apr 14).
  Collective symmetry breaking can be used to build composite Higgs models with "little Higgses", Higgs bosons whose masses are significantly smaller than the strong coupling scale. We will review the mechanism of collective symmetry breaking and examine it in action in the "Littlest Higgs" model of Nima and friends.
  Reference: hep-ph/0512128, hep-ph/0502182, hep-ph/0206021
• Dynamical SUSY Breaking, Jack Collins (21 Apr 14).
  It seems well established that we live in a universe with spontaneously broken supersymmetry. Apart from the question of where are the SUSY partners (we have already found nearly half of the components of the MSSM supermultiplets), we would like to know how SUSY is broken, and why (if SUSY has anything to do with gauge coupling unification) is there a hierarchy between the SUSY breaking scale and the Planck scale. The most attractive paradigm is that the SUSY breaking scale is generated by dimensional transmutation, i.e. it is associated with the strong coupling scale of an asymptotically free gauge theory, generated by logarithmic running of the gauge coupling from the Planck scale. I will give a whirlwind tour of model building themes along these lines, using some prototypical models to illustrate. The message will be that finding exactly stable SUSY breaking vacua is difficult and typically very fragile to deformations of the theory, requiring some elaborate model building, but finding long lived metastable SUSY breaking vacua in a theory with SUSY vacua is much more generic and in vogue.
  Reference: M. Bertolini, `Lectures on Supersymmetry', arXiv:hep-ph/0702069, J. Collins, A exam notes
• Quantum Field Theory in Curved Spacetimes, John Stout (28 Apr 14).
  Remember how Paul was able to derive the temperature of a black hole by expanding the geometry about the horizon, Wick rotating, and then periodically identifying time? That was weird, right? Yeah. I'd like to go through why that works, and along the way review a smattering of ideas in quantum field theory in curved space, like what goes wrong with the particle interpretation, vacuum selection, the Unruh effect and Hawking radiation.
  Reference:
• Quantum Field Theory in Curved Spacetimes, John Stout (5 May 14).
  So I completely underestimated the time it would take to cover this entire field. My bad. Fortunately, Mario has graciously allowed me to take his Journal Club spot to continue our collective foray into this wonderful and mysterious topic. Last time we talked about what particles are and used these definitions to talk about the Unruh Effect. I'll give a brief review of all of that, talk some more about the physical implications of the Unruh Effect in different frames. Then I'll talk about Hawking Radiation and hopefully have some cogent things to say about vacuum selection. Then, we'll finally get to this delightful trick that Paul showed us to coax the temperature out from the periodicity of Euclidean time.
  Reference: Birrell and Davies - Quantum Fields in Curved Spacetime, Mukhanov and Winitzki - Introduction to Quantum Effects in Gravity, gr-qc/0308048, gr-qc/0710.5373
• Talk 14, (12 May 14).
  Reference:
• Talk 15, (19 May 14).
  Reference:

Resources

Unsure about places to start looking for talk ideas? Here are a few suggestions, geared towards the pedagogical side.

• Collections of reviews and lectures: The Net Advance of Physics, Ulrich Theis' page, or The String Wiki.
• It may also be worth looking through journals that specialize in review articles: RMP, Physics Reports, Annual Reviews, Reports on Progress in Physics, Proceedings of Science, Living Reviews.
• You can also use tools like SPIRES and arXiv Structure to find papers and reviews. For example, you can search for proceedings from summer schools (TASI, Les Houches, SLAC, Cargese, Cracow)

Scanning: it is often helpful to share your notes with the journal club, especially for review talks. Hand written notes may be scanned easily using the LASSP document scanner on the 5th floor of Clark or Mann library (photocopiers with free scanning option). These have automatic document feeders and can e-mail you a pdf of your notes.

Guidelines

• Announce your topic two weeks in advance, include a link to the relevant paper(s).
• You should give one pedagogical talk and one 'new paper' talk over the course of the semester.
• All members are required to have read 'new papers' that are being presented. Pedagogical talks should be accessible without pre-reading. Review and 'new paper' talks should alternate to give students time to read the new paper.
• Use discretion when presenting a new paper; if it is based on a topic that is unfamiliar to our group, it would be better to coordinate a pedagogical talk before presenting the paper.
• Speakers should focus on leading a discussion rather than giving a 1.5 hour lecture; students are expected to participate actively. Chalkboard talks are strongly preferred.
• Because of the composition of pheno students we have, we are in a unique position to take advantage of this kind of activity. This will only work if we all make this a priority.

History

The current BSM journal club was started in 2007 by Flip Tanedo, David Curtin, Itay Nachshon, Josh Berger, and Yuhsin Tsai. Previous manifestations include a collider journal club organized by Matt Reece and Patrick Meade. In the distant past Michael Peskin explains that the students had a "Gradshteyn" seminar since it was meant to integrate the collective knowledge of the graduate students.