Theory Seminars Archive

Thursday, March 22, 2018

Speaker: Alberto Tonero

Time: 3:30PM -- 4:30PM

Location: HP4351

Title: TBA

Abstract: TBA


Thursday, March 8, 2018
Speaker: Jay Hubisz

Time: 3:30PM -- 4:30PM

Location: HP4351

Title: Self-Organized Higgs Criticality

Abstract: I will discuss how the critical point for a Higgs sector may be made a dynamical attractor in a way that parallels similar phenomena in statistical physics such as the sand-pile model, or fault slippage in earthquakes. In this construction, a modulus field has a potential which has (meta)stable minima precisely at points where, in the low energy effective theory, the Higgs field mass is vanishing. I will discuss how quantum corrections are not expected to spoil this Higgs criticality, and how there are no ultralight particles expected, in seeming violation of expectations from naive application of effective field theory.

Thursday, March 1, 2018

Speaker: Yuval Grossman

Time: 3:30PM -- 4:30PM

Location: HP4351

Title: Self-Destructing Dark Matter

Abstract: Self-Destructing Dark Matter (SDDM), a new class of dark matter models will be presented In this class of models, a component of dark matter can transition from a long-lived state to a short-lived one by scattering off of a nucleus or an electron in the Earth. The short-lived state then decays to Standard Model particles, generating a dark matter signal with a visible energy of order the dark matter mass rather than just its recoil. This leads to striking signals in large detectors with high energy thresholds. Examples of models which exhibit self-destruction, all inspired by bound state dynamics in the Standard Model will be presented.

Thursday, February 8, 2018

Speaker: Jean-François Fortin

Time: 3:30PM -- 4:30PM

Location: HP4351

Title: Conformal Field Theory in Embedding Space

Abstract: Conformal field theories (CFTs) are special quantum field theories (QFTs) with extra spacetime symmetries. Amongst other things, they play an important role in determining the phase diagrams of QFTs and in the study of second-order phase transitions in condensed matter physics. The extra spacetime symmetries of CFTs lead to an algebra of operators dictated by the operator product expansion (OPE). Contrary to QFTs where perturbation theory is often the only computational handle available, the existence of OPEs allows a specific understanding of CFTs through consistency conditions of correlation functions, even at strong coupling. In this talk we review conformal field theory and discuss the embedding space point of view. Contrary to position space where the conformal algebra action on fields is complicated, the conformal algebra action in embedding space is homogeneous and thus simpler. The use of embedding space allows an easier computation of the correlation functions and the associated conformal blocks from the OPEs in embedding space. The most general function appearing in the conformal blocks is obtained in terms of infinite sums on the conformal cross ratios. Several interesting properties of this function are found and it is shown that it is invariant under the dihedral group of order 12.

Thursday, February 1, 2018

Speaker: Jesse Thaler

Time: 3:30PM -- 4:30PM

Location: HP4351

Title: On the Topic of Jets

Abstract: When quarks and gluons are produced in high-energy collisions, their fragmentation and hadronization via QCD results in collimated sprays of particles called jets. While quark and gluon partons carry color charge, jets are composed of color-singlet hadrons, so there is no unambiguous definition of "quark" and "gluon" at the hadron level. Remarkably, a similar kind of problem is faced when analyzing the distribution of words in a set of documents, and there is a framework called "topic modeling" to identify emergent themes in a corpus without having to specify those themes a priori. In this talk, I present preliminary studies applying topic modeling to jet physics, and I speculate on a possible application of jet topics to extract the strong coupling constant.

Thursday, January 11, 2018

Speaker: Gabriel Lee

Time: 3:30PM -- 4:30PM

Location: HP4351

Title:  Bound State Formation for Dark Hadrons

Abstract:  Dark matter charged under a hidden nonabelian gauge group generically undergoes a confining phase transition in the early universe. Depending on the matter content in the model, this transition can produce a variety of colour singlet states in the confined phase, and these can undergo a second stage of annihilation. It has previously been claimed that this second-stage cross section is geometric. We examine this claim by calculating the cross section using two different methods.

Thursday, November 23, 2017

Speaker: Ahmed Ismail

Time: 3:30PM -- 4:30PM

Location: HP4351

Title: Signatures of New Anomalous Gauge Bosons

Abstract:  Gauge anomalies occur in nearly all Abelian extensions of the Standard Model without additional chiral fermions. The lack of detection of new particles suggests that if a new gauge boson exists, we can integrate out the heavy anomaly-canceling fermions at high scales to obtain a low-energy effective field theory with a non-conserved current. We review the construction of this theory and discuss its phenomenological applications, with a focus on the Wess-Zumino terms describing the effective low energy anomalies. In particular, we show that the requirement of theoretical consistency in dark matter models can lead to enhanced indirect detection signatures.

Thursday, November 9, 2017

Time: 2:00 PM -- 5:00 PM

 Location: HP4351

 Speaker: Jonathan Feng

 Title: FASER

 Speaker: Tracy Slatyer

 Title: Resummation for WIMPs

 Speaker: Michael Peskin

 Title: Extracting High-Precision Higgs Boson Couplings at the 250 GeV IL


Thursday, October 12, 2017

Speaker: Yongcheng Wu

Time: 3:30PM -- 4:30PM

Location: HP4351

Title: Searching for CPV effects in h->\tau\tau at the LHC and future e+e- collider

Abstract: TBD

Thursday, October 5, 2017

Speaker: Simon Caron-Huot

Time: 2:30PM -- 4:30PM

Location: HP4351

Title: When does the gluon reggeize?

Abstract: I will review the phenomenon of gluon reggeization, and how it controls the energy dependence of high energy forward scattering in perturbative QCD, from a modern perspective based on the eikonal approximation. I will present several novel applications, including its interplay with infrared logarithms and with the more standard evolution of parton distribution functions at small momentum fraction, and present recent progress toward determining the evolution to three-loops. Based on 1309.6521 and 1604.07417.