Joint Theory Seminar
Speaker: Filip Kos (UC Berkeley and LBNL)
Title: Conformal Bootstrap with Fermions
Host: Xiaochuan Lu
Room: 432
Abstract: We study conformal field theories with fermion operators using the
conformal bootstrap methods. This gives a new way to determine the
scaling dimensions of the known theories like Gross-Neveu-Yukawa
models in 3d. When available, we compare our results with previous
perturbative results. Our method is more general so we also use it to
study models that are not necessarily in perturbative regime, like N=1
supersymmetric extension of 3d Ising model which might have
realization in condensed matter systems. We speculate about the
existence of certain yet unknown CFTs.
User:
High-Energy Seminars
Time:
9:10am - 10:10am
Send Reminder:
Yes - 1 day 4 hour 0 minutes before start
Description:
High Energy Seminar
Speaker: Mia Liu (FNAL)
Title: The Phase 1 Upgraded FPIX in CMS
Host: John Conway
Room: 285
Abstract:The task of the CMS pixel detector is to provide high-resolution 3D space points required for charged particle track pattern recognition and bottom quark tagging. Situated closest to the interaction point just outside the beam pipe, the pixel detector has to be able to cope with the high data rates and radiation doses. The Phase-0 pixel detector was designed for the LHC nominal luminosity of 10^34 cm−2 s−1 and performed excellently during Run 1 and early Run 2 data-taking in 2015 and 2016. However, the LHC has exceeded its design luminosity in 2016 and the phase-0 detector suffered from dynamical inefficiencies, resulting in data loss and degraded tracking and vertex reconstruction performance. To cope with the more challenging environment, CMS planned a phase-1 upgrade of the pixel detector, which is expected to perform well until the High Luminosity LHC. The new forward pixel detector was constructed by US CMS institutions during 2015-2016 and installed in CMS in early 2017. The detector was quickly commissioned and transitioned smoothly to data-taking. In this talk, I will discuss the improved detector design as well as experiences from constructing and commissioning the forward part of the detector. I will also discuss the DC-DC converter failures observed last year and where we stand today in understanding this issue.
Description:
Mother's Day
User:
High-Energy Seminars
Time:
4:00am - 5:30am
Send Reminder:
Yes - 2 days 4 hour 0 minutes before start
Description:
Special Seminar
Speaker: Heather Logan
Title: Constraining exotic sources of electroweak symmetry breaking
Host: John Terning
Room: 432
Abstract: In the Standard Model (and most of its extensions), the electroweak gauge symmetry is broken by the vacuum condensate of an isospin-doublet scalar field: the famous Higgs field. But scalars
in larger isospin representations can also contribute to electroweak
symmetry breaking and to the masses of the W and Z bosons. In this
talk I'll explore the possibilities for such "exotic" contributions to the vacuum condensate and discuss their phenomenological consequences, which can be used in a generic way to experimentally constrain these scenarios.
User:
High-Energy Seminars
Time:
6:30am - 7:30am
Send Reminder:
Yes - 1 day 4 hour 0 minutes before start
Description:
Joint Theory Seminar
Speaker: Rachel Houtz
Title: Color Unified Dynamical Axion
Host: John Terning
Room: 432
Abstract: In this talk I present a model with an enlarged color sector which solves the strong CP problem via new massless fermions. Solutions to the strong CP problem with new massless fermions typically introduce a new gauge group which confines to turn the massless fermions into phenomenologically allowed bound states. One of these bound states can then be identified as a dynamical axion. The new group, however, has its own CP-violating theta angle, and so without more model building the strong CP problem remains. In our model, we invoke unification to relate the two theta angles. The spontaneous breaking of the unified color group into QCD and another confining group proves a source of naturally large axion mass due to small size instantons. This model naturally enlarges the axion mass versus axion scale parameter space well beyond that of invisible axion models.
Joint Theory Seminar
Speaker: Jiji Fan (Brown U)
Title: Higgscitement: Cosmological Dynamics of Fine Tuning
Host: Xiaochuan Lu
Room: 432
Abstract: The Higgs potential appears to be fine-tuned, hence very sensitive to values of other scalar fields that couple to the Higgs. I will discuss that this feature can lead to a new epoch in the early universe featuring violent dynamics coupling the Higgs to a scalar modulus. The oscillating modulus drives tachyonic Higgs particle production. I will present a simple parametric understanding of when this process can lead to rapid modulus fragmentation, resulting in gravitational wave production. A nontrivial equation-of- state arising from the nonlinear dynamics also affects the time elapsed from inflation to the CMB, influencing fits of inflationary models. Supersymmetric theories automatically contain useful ingredients for this
picture.
