Wednesday April 5 2023 at 10:45 am in DRL 4N12
Chris Hays – Oxford
High-precision measurement of the W boson mass with the CDF II detector
The mass of the W boson, a mediator of the weak force between elementary particles, is tightly constrained by the symmetries of the standard model of particle physics. We have performed the most precise measurement of the W boson mass using data corresponding to 8.8 inverse femtobarns of integrated luminosity collected in proton-antiproton collisions at 1.96 TeV center-of-mass energy with the CDF II detector at the Fermilab Tevatron collider. The measured value is in significant tension with the prediction.
Link to paper in Science
Wednesday March 22 2023 at 3:30pm in 2C8
Scott Thomas – Rutgers
New Physics Frontiers at the Large Hadron Collider
Thursday March 16 2023 at 11am in 4N9
Nathaniel Craig – UC Santa Barbara
Naturalness
Wednesday February 15 2023 at 3:30pm in 2C8
Maxim Pospelov (University of Minnesota)
Electric Dipole Moments: review and recent developments
The search for EDMs is one of the most motivated low-energy searches for New Physics that violates CP. I review the main mechanisms that convert fundamental CP-violating parameters of the SM (theta_QCD and Kobayashi-Maskawa phase) to the observable electric dipole moments (EDMs). In light of recent experimental progress, the EDMs connected to electron spin (paramagnetic EDMs) are calculated. The limit on QCD theta angle is 3 * 10^(-8) and somewhat subdominant to neutron EDM, but can be further improved. The Kobayashi-Maskawa phase contributes to paramagnetic EDMs at the level of 10^{-35} e cm in units of equivalent electron EDM, which is three orders of magnitude larger than what was previously estimated.
Wednesday January 25 2023 at 3:30pm in 2C8
Prachi Arvind Atmasiddha – University of Michigan
Observation of the Radiation Amplitude Zero Effect and the first
measurement of longitudinal-longitudinal diboson polarization fractions
using WZ events in high-pT phase space
In the standard model of particle physics, the spontaneous symmetry breaking of the complex
Higgs field gives rise to the massive Higgs boson and three Goldstone bosons. These Goldstone
bosons become the longitudinal components of the W and Z bosons. It is critical to study the
longitudinal-longitudinal interactions of two bosons. In this talk, I will present the first
measurement of different diboson polarization fractions using WZ fully-leptonic events (WZ →
lvll) in the W_0 Z_0-enhanced region with 139 fb-1 of data taken by the ATLAS detector at
√s =13 TeV. A non-zero longitudinal-longitudinal polarization fraction is expected to be
observed with more than 5 sigma sensitivity. The Radiation Amplitude Zero effect in WZ events
helps to reduce the transversal-transversal polarization fraction. Along with high-pT^Z selection,
this effect also increases the sensitivity of the longitudinal-longitudinal polarization fraction
measurement. I will present the first observation of the Radiation Amplitude Zero effect in WZ
events. I will also describe my contribution to the ATLAS New Small Wheel detector integration,
commissioning and test beam performance studies.
Thursday January 12 2023 at 11:15am in 3W2 (TBC)
Dr Shion Chen (Tokyo)
Quest for dark matter from the high-energy & low-temperature frontiers
While the cosmological properties of dark matter has been very well-established,
the lack of our knowledge about its mass puts us in a situation of searching a mass range of >10^30 order of magnitude difference in the direct detection program.
From the heavy side, the WIMP dark matter in GeV-TeV has been the most theoretically motivated candidate e.g. by SUSY,
and the direct production in the energy frontier collider is one of the most effective probes.
On the light end, bosonic wave-like dark matter is viable below eV, realized by e.g. axion(-like particles) or dark photon.
The search experiments particularly gain wider attention lately because of the advancement of cryogenic and quantum technologies driven by the rise of superconducting quantum computers.
This seminar will discuss the recent results of the SUSY dark matter searches in LHC/ATLAS – which just started to show its real potential with the full Run2 data statistics – as well as the haloscope experiments targeting axions and dark photon, with a particular focus on the potential leap achieved by the introduction of superconducting qubits in the future.
Wednesday January 11 2023 at 3:30pm in 2C8
Dr Jeff Dandoy (Penn)
Novel Searches for Electroweak Supersymmetry and the ATLAS HL-LHC Upgrade of the Silicon Strip Detector
There are several observed phenomena incompatible with the Standard Model of particle physics, including dark matter and the light mass of the Higgs boson. Recent hints of additional anomalies have brought increased motivation to search for Electroweak Supersymmetry at the LHC. Several new results from the ATLAS Collaboration are presented targeting models with both R-parity conserving and violating decays into three-lepton final states as well as prospects for future searches including new final states. The High Luminosity upgrades of the LHC and the ATLAS experiment will greatly expand our ability to produce and detect rare new physics processes but presents unique challenges from a busy, high-radiation environment. Recent developments in the design and testing of the upgraded readout electronics of the charged-particle tracking silicon strip detector are discussed.
Wednesday August 31 at 3:30pm in 2C8
Professor Michelle Dolinski (Drexel)
EXO-200 recent results and nEXO outlook
The discovery of neutrino mass is direct evidence of physics beyond the Standard Model.
It is an experimentally open question whether neutrinos have Majorana masses, and neutrinoless double beta decay is the most promising experimental technique to search for Majorana neutrinos. EXO-200 and nEXO are part of a program to search for neutrinoless double beta decay of Xe-136 using single phase liquid xenon time projection chamber technology. I will report on recent results from the EXO-200 experiment, which ran from 2011 to 2018 at the Waste Isolation Pilot Plant in Carlsbad, NM. I will also discuss technical progress toward nEXO, a next generation experiment with a projected 10-year half-life sensitivity of 1.35×1028 yr at 90% confidence level.
Wednesday September 28 at 3:30pm in 3W2 (Joint Experimental/Theoretical)
Dr Johannes Michel (MIT)
Precision Physics & Proton Structure at the LHC
The LHC precision program critically relies on precise theory predictions for Standard-Model baseline rates to identify possible deviations due to New Physics and extract Standard Model parameters like the W mass. In this talk, I will present third-order QCD predictions for Higgs, Z, and W boson production at the LHC, with a particular focus on their transverse-momentum (qT) distributions, and including fully realistic fiducial acceptance cuts on their decay products. I will discuss how the resummation of large logarithms of qT, which is governed by the factorization of the cross section in terms of transverse-momentum dependent (TMD) PDFs, gives rise to a net resummation effect even in total cross sections in the presence of fiducial cuts. I compare our predictions for the Z boson transverse-momentum spectrum to high-precision measurements by the ATLAS and CMS experiments, discussing in turn the estimation of residual perturbative uncertainties, parametric uncertainties from the strong coupling and collinear PDFs, and uncertainties arising from the nonperturbative transverse structure of the proton as encoded in TMD PDFs and their evolution. I conclude by discussing synergies with the TMD program at the future Electron-Ion Collider at BNL and ongoing computational campaigns in lattice QCD.
Wednesday October 26 at 3:30pm in 2C8
Dr Julia Gonski (Columbia)
Searching for Uncovered and Unexpected New Physics Signatures at the Energy Frontier
The 2012 discovery of the Higgs boson with the Large Hadron Collider (LHC) was a groundbreaking achievement for high energy physics. Remaining puzzles such as dark matter confirm the need for beyond the Standard Model physics, and the Higgs boson can be used as a compass to determine its nature. This talk focuses on novel ATLAS searches in under-covered phase space, specifically long-lived particles and heavy resonances, that make use of the Higgs along with advanced data analysis techniques such as machine learning and anomaly detection for broad sensitivity. The High Luminosity LHC, the corresponding ATLAS detector upgrade, and studies for future colliders are all crucial for the longevity of these searches. These topics are discussed in the context of long-term planning for future experiments and the continued success of the field.
Wednesday November 30 at 3:30pm in 4C2
Professor Lam Hui (Columbia)
Black hole perturbation theory: Love numbers and nonlinear ring down.
We will briefly review black hole perturbation theory and discuss two new developments: (1) the symmetry reason behind the well known vanishing of the Love numbers, which characterize a black hole’s static tidal response; (2) the generation and production of first and second order quasi-normal modes in the ring down of a black hole. If time permits, we will also discuss the black hole as a probe of new light degrees of freedom, including wave dark matter such as an axion.
Note also annual review article on wave dark matter https://arxiv.org/abs/2101.11735
Wednesday December 14 at 3:30pm in 2C8
Dr Mark Palmer (BNL)
Future Colliders
The speaker is the director of the accelerator test facility at BNL and an expert on future colliders.