Nuclear and Particle Physics Colloquium (NPPC)


 

Mondays  |  Refreshments 3:30 PM  |  Talk: 4:00 PM  |  Kolker Room, 26-414

 

Committee: William Detmold, Chair ~ Daniel Harlow ~ Philip Harris ~ Or Hen

Colloquia Archives

Spring 2019

 

hosted by: Will Detmold

Lee Roberts, Boston University

Searching for Physics Beyond the Standard Model with the World’s Largest Penning Trap

Abstract: Measurements of the magnetic moments of the electron and muon were intertwined with the development of the “modern physics” of the 20th century. For the muon, this trend continues, perhaps pointing to New Physics beyond the Standard Model (BSM). The magnetic moment is along the spin,

μ=g Qe/2m ⃗s

For leptons, the factor g is greater than the Dirac value of 2 because of radiative corrections, so g =2(1+ a), or equivalently a = (g-2)/2, where a is the magnetic anomaly. While the value of the muon anomaly is dominated by the lowest-order Schwinger term α/2π≃ 0.00116⋯, it is necessary to include higher order contributions from QED, as well as contributions from the strong interaction and electroweak gauge bosons, to compare with the experimental value. The SM value now has an uncertainty of 0.3 parts per million (ppm), and the experimental value has an uncertainty of ± 0.54 ppm. The experimental value is larger than the Standard Model value by ≃ 3.7 standard deviations, which could come from new, as yet undiscovered BSM physics. To clarify this situation, a new experiment, E989 with the total error budget of ±0.14 ppm has been mounted at Fermilab and will soon begin the second data collection period. I will review the history of what we have already learned from previous (g-2) experiments, the physics reach of 989, and will report on its present status.

time:    4:00 p.m.
place:   Kolker Room (26-414)


(refreshments at 3:30 p.m.)


 

Presidents' Day Holiday - No Talk this Week

 

hosted by: Will Detmold

Annika Peter, OSU

What's Up with the Sun?

Abstract: The Sun is a popular target for dark matter searches, but there is one problem: the Sun is a mystery source of GeV-TeV gamma-rays. What we suspect is that the Sun does not shine at these energies on its own power, but because Galactic cosmic rays (CR) interact with its matter and light. By observing and modeling these interactions in and near the Sun, one may learn about CR propagation in the inner heliosphere and in the solar atmosphere, and remove this important foreground for dark matter searches. In this talk, I will present observations and a set of ongoing calculations that sharpen our understanding of how the Sun interacts with CR. From data taken with Fermi/LAT and ground-based air shower arrays, I will show that the Sun is a luminous source of gamma rays up to at least 300 GeV, with time and spatial variability that anti-correlates with the solar activity cycle. I will show how confounding these results are for any plausible model of CR-driven emission. I will show that neutrinos from the same CR-Sun interactions are a complementary probe of CR propagation, even as they are problems for dark matter searches, and highlight the prospects for IceCube and future neutrino experiments to detect this exciting new astrophysical signal.

time:    4:00 p.m.
place:   Kolker Room (26-414)


(refreshments at 3:30 p.m.)


 

No Talk this Week

 

hosted by: Phil Harris

Gregor Kasieczka, UHH

Seeing the Unimagined: Unsupervised Discovery of New Physics at the LHC

Abstract: Many experimental results from both particle and astrophysics hint that the Standard Model (SM) of particle physics cannot be a complete theory of Nature. However, in its first years of operation, the LHC was very successful in excluding large regions of parameter space for potential models beyond the SM. We present how deep learning—algorithms based on neural networks with large numbers of internal layers—can be used to search for deviations from the SM. Specifically, we show that unsupervised learning based on deep autoencoders can be directly trained on data and used for model-independent searches for new physics - reducing experimental systematic uncertainties and reliance on specific theories at the same time. Beyond autoencoders, we discuss other physics scenarios as well as wider applications of deep learning.

time:    4:00 p.m.
place:   Kolker Room (26-414)


(refreshments at 3:30 p.m.)

 

hosted by: Or Hen

Augusto Macchiavelli, Lawrence Berkeley National Laboratory

Frontiers of Nuclear Structure Physics

Abstract: Atomic nuclei constitute unique many body systems of strongly interacting fermions. Their properties and structure are of paramount importance in many areas of physics. Phenomena encountered in nuclei share basic ingredients with other mesoscopic systems, and nuclei continue to offer unique laboratories to study these phenomena.

The structure of nuclei far from the stability line is a central theme of research in Nuclear Physics. Key to this program has been the worldwide development of radioactive beam facilities and novel detector systems, which provide the tools needed to produce and study these exotic nuclei.

Some of the interesting aspects currently being addressed concern the role played by different parts of the nuclear force in the evolution of shell structure and collectivity with isospin, and the effects of weak binding. In this talk I will present some selected examples of recent results that shed light on these topics.

I will end the presentation with a short review of the gamma-ray tracking technique, that marks a major advance in the development of γ-ray detector systems and can provide order-of-magnitude gains in sensitivity compared to existing arrays. A 4π tracking-array will be a powerful instrument needed in a broad range of experiments that will play an essential role in addressing the intellectual challenges of low-energy nuclear science. Developments of these instruments are underway both in the US (GRETINA/GRETA) and Europe (AGATA).

*Work supported by the US-DOE under contract number DE-AC02-05CH11231.

time:    4:00 p.m.
place:   Kolker Room (26-414)


(refreshments at 3:30 p.m.)


 

Spring Break - No Talk this Week


 

hosted by: Or Hen

Michael Williams, MIT

Moriond on the Charles

Abstract:I will present a number of new results unveiled by the LHCb experiment at the Moriond conferences in the past few weeks. This includes the discovery of 3 narrow pentaquark states, which appear to be the first clear observations of meson-baryon bound states, and the first observation of CP violation in charm decays.

time:    4:00 p.m.
place:   Kolker Room (26-414)


(refreshments at 3:30 p.m.)


 

hosted by: Phil Harris

Heather Gray, UCB/LBNL

The Higgs and The Quarks; Probing the Yukawa Couplings of the Higgs Boson

Abstract: The discovery of the Higgs boson at the LHC in 2012 relied predominantly on studies of the bosonic decay modes. However, there is a rich structure in the Yukawa sector of the Higgs boson within the Standard Model. Studies of the direct coupling of the Higgs boson to fermions can be used to probe the proportionality of this coupling to the fermion mass and hence the test the fermionic mass generation mechanism. I will introduce current experimental studies in the Higgs to quark sector and, in particular, the recent observation at the LHC for the coupling of the Higgs to heavy quarks. I will discuss some of the important experimental challenges and highlight new ideas for the future.

time:    4:00 p.m.
place:   Kolker Room (26-414)


(refreshments at 3:30 p.m.


 

Patriots Day Holiday - No Talk this Week

 

hosted by: Phil Harris

John Alison, Carnegie Mellon University

Di-Higgs Production at the LHC: Current Status and Future Prospects

Abstract: Processes involving pairs of Higgs bosons are a sensitive probe of new physics and will ultimately allow the shape of the Higgs potential to be directly explored experimentally. I will discuss the motivations and experimental challenges of searching for Di-Higgs production at the LHC. Emphasis will be placed on the dominant hh->4b channel.

time:    4:00 p.m.
place:   Kolker Room (26-414)


(refreshments at 3:30 p.m.

 

hosted by: Daniel Harlow

Tien-Tien Yu, University of Oregon

Dispatches from the sub-GeV Dark Matter Frontier

Abstract: The sub-GeV dark matter mass range has received increased interest in the last several years, owing to the lack of any unambiguous signal of the canonical WIMP in the GeV-TeV mass range. The sub-GeV mass range is relatively unexplored due to the difficulty of detecting such light dark matter with traditional techniques. However, there have been recent experimental developments that finally make sub-GeV direct detection viable.

I will discuss some of the theoretical principles and strategies to explore sub-GeV dark matter candidates, as well as some current and proposed experimental techniques. I will focus predominantly on semiconductor targets, such as the new SENSEI experiment which utilizes silicon CCDs, and demonstrate the potential for exploring the eV-GeV dark matter mass range in the near future.

time:    4:00 p.m.
place:   Kolker Room (26-414)


(refreshments at 3:30 p.m.

 

hosted by: TBA

Daniel Jafferis, Harvard University

Traversable Wormholes

Abstract: The gauge/gravity correspondence relates quantum entanglement to spatial connection by an Einstein-Rosen bridge. I will describe a configuration in which quantum teleportation is experienced by the teleportee as travel through such a wormhole, rendered traversable by the teleportation protocol. I will discuss some implications for physics behind black hole horizons, the information paradox, and the nature of observables in quantum gravity.

time:    4:00 p.m.
place:   Kolker Room (26-414)


(refreshments at 3:30 p.m.)


 

hosted by: Iain Stewart

Claude Duhr, Université Catholique de Louvain

From Pure Mathematics to Precision Physics: Modern Approaches to Scattering Amplitudes

Abstract: The computation of quantum corrections to scattering processes has for a long time been hampered by the complexity of the integrals involved.

In recent years there was tremendous progress in this area, partly due to the discovery of deep connections between scattering amplitudes and certain branches of pure mathematics.

I will review these connections and discuss how they can be turned into new powerful tools for precision computations.

time:    4:00 p.m.
place:   Kolker Room (26-414)


(refreshments at 3:30 p.m.)