List of past RPMs — 2018

Jan 09, 2018

Oindree Banerjee (Ohio State University) “Searching for ultra-high-energy neutrinos with the Antarctic Impulsive Transient Antenna “

Ultra-high-energy (> 10^18 eV) neutrinos remain undiscovered in this era of rapid growth in multi-messenger astronomy. These neutral and weakly-interacting particles can travel cosmic distances without attenuation and point straight back to their source, rendering them promising messengers. Detection of these elusive particles requires an enormous instrumented volume of a dielectric material such as water, ice, salt, etc. Use of radio Cherenkov method enables this at a relatively low cost. The Antarctic Impulsive Transient Antenna (ANITA) is a NASA-funded long-duration balloon experiment that is launched from near McMurdo Station, Antarctica, to fly over the continent in roughly circular orbits in the stratosphere for a month. ANITA looks for the radio signature from ultra-high-energy neutrino interaction in the ice below. There have been four flights of ANITA so far. I will review the principles underlying radio detection of neutrinos by ANITA, the ANITA instrument and recent developments in the hardware and electronics of ANITA. I will show results from the currently ongoing search for a diffuse flux of neutrinos in the data from the third flight of ANITA.
I received my Bachelor’s degree in Physics from North Carolina State University. Currently, I am a 5th year graduate student in Physics at Ohio State University. For the ANITA-IV mission, I built, tested and deployed electronics which, for the first time, were able to dynamically filter anthropogenic noise at tunable frequencies. These filters helped to triple the “effective livetime” of ANITA-IV compared to ANITA-III. In analysis, I am working on new techniques for background rejection using data from the ANITA-II and ANITA-III flights.

Jan 11, 2018

Mengjiao Xiao (University of Maryland) “Probing the Nature of the Universe from the Chinese Underground Experiments”


Despite the tremendous success of the Standard Model (SM) of particle physics, it becomes more and more clear that the SM is far from complete. For example, the non-zero neutrino mass was the first solid evidence beyond the SM, but we still do not understand why neutrinos are so light, and if they are their own anti-particles. We know that the mass of the universe is dominated by dark matter, but we do not understand the nature of the dark matter. Exploring these unknowns may lead to fundamental science discoveries and deepen our understanding of the universe.

Due to their feeble interactions with normal matter, both neutrinos and dark matter are studied under low background environment in underground laboratories. This area of research is booming in China with a few underground facilities in operation or under construction. The first half of my talk will introduce the Jiangmen Underground Neutrino Observatory (JUNO), an experiment aiming to determine the neutrino mass ordering and to precisely measure oscillation parameters using a large liquid scintillator detector. I will then discuss the PandaX project, a series of experiments using dual-phase xenon for dark matter direct detection in the China Jin-Ping underground Laboratory.


Mengjiao Xiao, Ph.D. of Shanghai Jiao Tong University in 2016, now is postdoc at University of Maryland, College Park. Working on PandaX and JUNO experiment.

Jan 23, 2018

Chihway Chang (KICP/U. Chicago) “Cosmic Surveys in the Next Decade: Mapping the Landscape of the Universe”

Cosmology in the next decade will be driven by data. Exploiting the information one can extract from the ongoing and upcoming large surveys will give us the power to stress-test the LCDM model with unprecedented precision and open up windows for new physics. In this talk I will present some of our work in the Dark Energy Survey Collaboration and the Large Synoptics Survey Telescope Dark Energy Science Collaboration, to analyse state-of-the-art galaxy survey data as well as getting ready for the next generation of data. I will focus on topics surrounding weak lensing analyses, including cosmology from 2-point functions, generating weak lensing mass maps, and measuring the mass profiles at the outskirts of galaxy clusters.

Jan 25, 2018

John Alison (U. Chicago) “Di-Higgs Production at the LHC: Current Status and Future Prospects”


I will discuss motivations for searching for di-Higgs production at the LHC.  Recent results and projected sensitivities will be presented with emphasis on the dominant hh->4b channel.

Jan 30, 2018

Alex Drlica-Wagner (FNAL) “Using Cosmic Surveys to Understand the Fundamental Nature of Dark Matter”


The existence of dark matter is strong evidence for new physics beyond the Standard Model. While laboratory and collider searches for dark matter have advanced rapidly over the past several decades, astrophysical observations currently provide the only robust, positive, empirical measurement of dark matter. Astrophysical observables can be directly linked to the fundamental properties of dark matter, such as particle mass, self-interaction cross section, and self-annihilation rate. In this talk, I will discuss how the Fermi Large Area Telescope (LAT) and the Dark Energy Survey (DES) have advanced our understanding of dark matter from observations of the smallest and most dark-matter-dominated galaxies. In addition, I will discuss opportunities to build a cohesive dark matter program with the Large Synoptic Survey Telescope (LSST).

Feb 01, 2018

Jason Bono (FNAL) Physics and Mathematics in Music


Music is nearly universal in human culture and yet it remains
mysterious. In order to help answer some of music’s fundamental
questions, we will briefly turn to archeology and early history before
examining some of music’s salient features from a physical and
mathematical perspective. Principles rooted in physics and pure
mathematics will provide a link to intercultural qualities of musical
tone and melody to the deep role that symmetry plays in human
perception, thus shedding light on the questions that we set out to
answer. To enhance clarity and familiarity, various concepts will be
illustrated with animations and sound bites.

Feb 06, 2018

Heather Gray (LBNL) Title: The Higgs and the Quarks; Probing the Yukawa couplings of the Higgs boson


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.  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 quark sector and, in particular, the recent evidence obtained 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.

Feb 08, 2018

Daniel Scolnic (U. Chicago) “Measuring Dark Energy with Supernovae and Kilonovae”


The next decade will be the golden age of cosmology with transients. In this talk, I will present new analyses of Type Ia Supernovae that mark the most precise measurement of dark energy to date. I will go over how this analysis ties together with the analysis of the local value of the Hubble constant, for which tension persists with the inferred value from the CMB – an exciting hint at possible departures from the standard cosmological model. I will then discuss the first measurements of the Hubble constant with kilonovae and gravitational waves. I will review the large amount of overlap between the issues that must be tackled for future progress using supernovae and kilonovae to measure cosmological parameters. Finally, I will discuss the roles that surveys like LSST and WFIRST will play and how we can harness the millions of transients discovered to make generation-defining cosmological measurements.

Feb 13, 2018

Zeynep Demiragli (CMS / MIT) “Search for Dark Matter: CMS Strikes Back!”


The experiments at the Large Hadron Collider (LHC) at CERN are at the energy frontier of particle physics, searching for answers to fundamental questions of nature. In particular, dark matter (DM) presents strong evidence for physics beyond the standard model (SM). However, there is no experimental evidence of its non-gravitational interaction with SM particles. If DM has non-gravitational interactions with the SM particles, we could be producing the DM particles in the proton-proton collisions at the LHC. While the DM particles would not produce an observable signal in the detector, they may recoil with large transverse momentum against visible particles resulting in an overall transverse momentum imbalance in the collision event. In this talk, I will review the searches for DM particles in these missing momentum final states at the Compact Muon Solenoid (CMS) experiment. I will also discuss the prospects for discovering dark matter at the High Luminosity-LHC and other future experiments.

Feb 15, 2018

Haichen Wang (LBNL) Title: The Higgs boson and the top quark share the stage


The top quark plays an important role in the collider phenomenology of the Higgs boson, and the study of the interplay between the top quark and the Higgs boson may provide key insights to some critical questions in particle physics. A milestone in the experimental study of the top-Higgs sector of the Standard Model will be the observation of the Higgs boson production in association with top quarks (ttH), a direct evidence for the top-Higgs Yukawa coupling. With 36.1 fb-1 pp collisions at 13 TeV, the ATLAS experiment performed searches for the ttH production in several channels and found the evidence for this production. In this talk, I start with a brief overview on the experimental understanding of the Higgs boson properties and motivate the study of the top-Higgs Yukawa coupling. I then present the ATLAS ttH searches with a focus on the diphoton channel. In the end, I discuss the prospect of the ttH study and its impact on other aspects of the LHC physics program.

Feb 20, 2018

Lauren Tompkins (Stanford U.) “The World’s most complicated game of Bingo: Pattern Recognition at the Energy-Intensity Frontier”


In 2012 the ATLAS and CMS experiments discovered the Higgs Boson, firmly establishing the Standard Model as the dominant paradigm for subatomic particle interactions.  Many expected the Higgs discovery to be one of several discoveries at the energy frontier, yet five years later it remains the single addition to the subatomic particle pantheon.  Meanwhile, the LHC has begun to push the boundaries of the hadron collision intensity frontier, yielding large datasets for further understanding the Standard Model as well as continuing the increasingly difficult search for new physics.  I will discuss a path through the intensity frontier, focusing on a hardware based, real-time pattern recognition engine which will enable the ATLAS experiment to fully exploit the delivered data by playing the world’s most complicated game of bingo.

Feb 27, 2018

Julien Guy (LBNL) “The DESI Project, Construction Status and Prospects for Precise Cosmological Distance Measurements with Lyman-Alpha Forests”

The Dark Energy Spectroscopic Instrument is a multi-object spectrograph composed of a wide field corrector, a 5000 robotically positioned fiber system, and 10 3-arms spectrographs. The instrument is installed this year on the Mayall 4-m diameter telescope at Kitt Peak, Arizona. Operations will start next year. In 5 years, DESI will measure spectra and redshifts of more than 30 million galaxies and quasars. This catalog will be used to measure the expansion history of the Universe and the growth rate of structure in the past 10 billion years with sub-percent precision. I will present the construction status and give some insight on the Lyman-alpha BAO analysis.

Mar 15, 2018

Peter Mohr (NIST) “The New SI and Fundamental Constants”

The International System of Units (SI) is expected to undergo a revolutionary change on
May 20, 2019. In October 2017, the International Committee on Weights and Measures met
at the International Bureau of Weights and Measures near Paris and recommended a new
definition of the SI such that a particular set of constants would have certain values when
expressed in the new SI units. In particular, the new SI would be defined by the statement:
The International System of Units, the SI, is the system of units in which

  • the unperturbed ground state hyperfine splitting frequency of the
  • caesium 133 atom Cs is 9 192 631 770 Hz,
  • the speed of light in vacuum c is 299 792 458 m/s,
  • the Planck constant h is 6.626 070 15× 10?34 J/Hz,
  • the elementary charge e is 1.602 176 634×10?19 C,
  • the Boltzmann constant k is 1.380 649×10?23 J/K,
  • the Avogadro constant NA is 6.022 140 76×1023 mol?1,
  • the luminous efficacy Kcd of monochromatic radiation of frequency 540×1012 hertz is 683 lm/W

The numerical values of the constants were determined by a special CODATA adjustment of
the values of the constants using data in papers that were accepted for publication by July
1, 2017.
The Convention of the Meter (Convention du M`etre), a treaty that specifies international
agreement on how units are defined, was established in 1875 with 17 nations initially signing
on, including the U.S. The SI, established within the treaty in 1960, is more recent and
continues to evolve. Currently, the treaty is agreed to by fifty-eight Member States, including
all the major industrialized countries. Even though a majority of people in the U.S. still
use units such as inches and pounds, the official standards for these units are based on the
SI units, so the U.S. national measurement standards will also be redefined, although the
change will be imperceptible in every-day use.
The redefinition will have a significant impact on the fundamental constants when ex-
pressed in SI units. Not only will the defining constants be exact, but many others will also
be exact, and still others will have considerably reduced uncertainties. This reflects a shift
from macroscopic measurement standards to quantum based standards.
This talk will describe the new SI, review reasons for the change, and show how units
can be based on assigned values of certain physical constants.

Mar 20, 2018

Simone Ferraro (LBNL) “Lighting up the Dark Universe”

Recent progress in cosmological observations reveal a simple yet strange universe. Our preferred cosmological model relies on mysterious components such as Dark Matter, Dark Energy and an early period of accelerated expansion. The challenge in the next decade will be to understand the nature of these components and reveal new aspects of fundamental physics.
I will discuss the synergies between upcoming redshift and CMB experiments and show that thanks to sample variance cancellation techniques, a large improvement on constraining power is possible even at fixed volume. I will highlight the role of cross-correlations and velocity fields in increasing the statistical power of future surveys, while at the same time allowing for greater control of systematics. I will show how the combination of large-scale structure and CMB experiments hold great promise to reveal the secrets of our mysterious Universe.

Mar 22, 2018

Andreu Font (U. College London) – “Cosmology with the Lyman alpha forest: challenges and opportunities””

From 2009 to 2014, the Baryon Oscillation Spectroscopic Survey (BOSS) used the SDSS telescope to obtain spectra of 1.5 million galaxies to get very accurate measurements of the Baryon Acoustic Oscillations (BAO) scale at redshift z ~0.5. At the same time, BOSS observed over 184 000 high redshift quasars (z>2.15) with the goal of detecting the BAO feature in the clustering of the intergalactic medium, using a technique known as the Lyman alpha forest (LyaF). In this talk I will overview the final results from the LyaF working group in BOSS, including the measurement of BAO at z=2.4 both from the auto-correlation of the LyaF (Bautista et al. 2017), and from its cross-correlation with quasars (du-Mas-des-Bourboux et al. 2017). From the combination of these studies we are able to measure the expansion rate of the Universe 11 billion years ago with a 2% uncertainty.

Starting in 2019, the Dark Energy Spectroscopic Instrument (DESI) will increase this dataset by an order of magnitude. In this talk I will review the challenges that we will face in order to provide an exquisite measurement of the expansion over cosmic history, and the opportunities that we will have to study other fundamental questions: the sum of the mass of the neutrino species, properties of dark matter particles, and the shape of the primordial power spectrum of density fluctuations.

Mar 27, 2018

Lisa Barsotti (MIT) “Squeezing the most out of gravitational wave detectors”


The recent observations of gravitational waves have been enabled by a new generation of LIGO detectors, Advanced LIGO, the most sensitive laser interferometers ever built. In my talk I will review the main scienctific results from the first two Observing Runs, O1 and O2, and discuss the status of the Advanced LIGO detectors and plans for O3. I will also describe prospects for further extending the astrophysical reach of ground-based observations with future generations of detectors.

Mar 29, 2018

Sven Vahsen (University of Hawaii) – Directional Dark Matter Searches via Charge Cloud Tomography

With WIMP-nucleon scattering limits approaching the neutrino floor, and coherent neutrino-nucleon scattering experimentally established, there is renewed interest in directional detectors as a means to penetrate the neutrino floor. The CYGNUS collaboration aims to deploy multiple gas Time Projection Chambers (TPCs) to accomplish this. I will review recent R&D work carried out within CYGNUS, with a focus on efforts at the University of Hawaii. I will discuss recently deployed directional neutron detectors capable of imaging the 3D surface shape of nuclear recoils with high resolution. These existing detectors represent a stepping stone towards larger detectors capable of providing fully tomographic 3D images of nuclear recoils. I will discuss how 3D recoil imaging is relevant to dark matter detection by enabling several new measurement techniques. Time permitting, I will also discuss a conceptual design study that compares the suitability of different technological approaches to a large-scale nuclear recoil observatory with sensitivity to both WIMP dark matter and neutrinos.

Apr 03, 2018

Brice Menard (JHU) and Ting-Wen Lan (IPMU) – Twenty years of SDSS spectra: lessons for DESI

We have played with SDSS spectra for almost two decades and enjoyed performing all sorts of statistical analyses with them. In this talk we will take a critical look at these explorations and discuss what has worked well and what has not, what mistakes were made and some of the fundamental limits arising from the calibration of the data — all of which are informative to prepare ourselves for the DESI era. Finally we will also discuss new data analysis ideas and emerging techniques that are likely to impact the way we think and manipulate spectra in the near future.

Apr 05, 2018

Colin Hill (IAS) – “Fundamental Physics from the Foreground-Obscured Microwave Sky: Inflation, Neutrino Masses, and Beyond”

The cosmic microwave background (CMB) remains a key source from which to extract information about fundamental physics, due to its clean, well-understood origin and immense constraining power on many types of new physics. The next decade of CMB observations will yield answers to at least two fundamental questions: (1) did large-field inflation source the initial density perturbations in our universe? (2) what is the absolute mass scale of the neutrinos? In this talk, I will explain the routes by which these answers will be obtained. Both rely on highly precise measurements of the polarization of the CMB, which can be used to search for the signature of primordial gravitational waves (answering the first question) and to measure the growth of cosmic structure via gravitational lensing (answering the second question). Moreover, I will describe new methods with which to overcome the most significant challenge to this program: emission from non-primordial foreground sources. I will highlight the major role that the Simons Observatory and CMB-Stage IV experiments will play in these exciting developments. Finally, I will describe additional unique information about the distribution and properties of baryons and dark matter that these measurements will yield, providing crucial feedback for cosmological analyses with DESI and other large-scale structure surveys.

Apr 12, 2018

George Smoot (UCB/LBNL) “Reinterpreting Low Frequency LIGO/Virgo Events as Gravitationally-Lensed Magnified Stellar-Mass Black Hole Mergers at Cosmological Distances”

Though dismissed by most, we claim that strong gravitational lensing of the gravitational waves for merging black holes explains the high mass binary black hole mergers observed by LIGO/Virgo explains the apparent 30 M_Sun events better than any alternative models.
It turns out to be difficult to make large mass black hole binaries in sufficient number to explain LIGO’s results. However, strong gravitational lensing of cosmological distant mergers can naturally explain them while the redshift of the orbital frequencies amplifies the observed apparent masses.

Apr 19, 2018

Paolo Calafiura (LBNL) HL-LHC Computing Challenges

The current models for HL-LHC computing show order-of-magnitude resource shortages with large uncertainties. Business-as-usual is not an option unless we accept limiting HL-LHC physics reach, particularly for precision studies.
A  grassroots initiative called the HEP Software Foundation has been collecting ideas and pooling efforts to perform the necessary R&D to meet these O($100M) resource shortages. HSF produced a Community White Paper that has been endorsed by the LHC experiments, the Worldwide LHC Computing Grid, and some funding agencies.
 I will briefly review some of the technical and organizational challenges ahead of us as we turn the Community White Paper into a research program, and try to present some of the exciting new R&D ideas we are prototyping at Berkeley Lab and elsewhere.

Apr 26, 2018

Gustavo Branco (CFTP-IST, Univ. de Lisboa, Portugal) – “Multi-Higgs Models, The Flavor Problem and the Origin of CP Violation”

We analyse two-Higgs-Doublet extensions of the Standard Model, paying special attention
to novel mechanisms for natural suppression of scalar Flavor-Changing-Neutral-Currents
and their imllementation in specific models. Some of the most salient implications of these models will be presented. The possibility of having realistic models of spontaneous CP violation will be studied.

May 03, 2018

Alan Schwartz (University of Cincinnati) “Challenging the Standard Model with the Belle(II) Experiment”


The Belle experiment in Japan began taking data in the late 1990’s and went on to record the world’s largest sample of B-anti-B meson pairs produced in a quantum correlated state. This initial state allowed Belle, and the BaBar experiment at SLAC, to measure CP violation in B decays with high accuracy. These measurements contributed to the awarding of the 2008 Nobel Prize in Physics to Kobayashi and Maskawa for their theory of CP violation. However, other measurements have exhibited discrepancies with the Standard Model, e.g., measurements of |Vub| and |Vcb| , R(D) and R(D*), etc. Over the past several years, the Belle detector and accelerator complex have been rebuilt and significantly upgraded to become the Belle II experiment. Belle II is designed to record 50 times the data set that Belle recorded, and with much improved detector performance. This forthcoming data should resolve several discrepancies observed by Belle and BaBar. Here we review some recent results from Belle and discuss the physics program and current status of Belle II.

May 10, 2018

Christian Bauer (LBNL) “GENEVA: Combining perturbative calculations with parton showers”


I will discuss the event generator GENEVA, which for the first time combines fixed order and resummed perturbative calculations with parton showering and hadronization. I will explain the basic physics concepts underlying GENEVA, and show how they can be used to achieve in principle any accuracy desired. After presenting physics results on the production of vector boson + jets at the LHC, I will finish by giving an overview of how to use GENEVA.

May 17, 2018

Chris Fassnacht (UC Davis) “Cosmological parameters from strong gravitational lenses”

Recent measurements of the Hubble Constant (H_0) through distance
ladder techniques have revealed a noticeable tension with the
Planck H_0 value that was obtained under the assumption of the cosmological
“standard model”, i.e., a flat Lambda cold dark matter cosmology. Is this
tension an indication that modifications to the standard model are
necessary, or is it the sign of unknown systematic effects in one or
both of the techniques? To address this question requires additional
high-precision measurements with techniques that are independent of
the distance ladder. The time delay strong lensing technique, in
which gravitational lensing by a massive galaxy produces multiple
images of a time-variable quasar, fulfills these requirements. I will
present recent results from the H0licow program, in which the analysis
of just three time-delay strong lenses has produced a 3.8% measurement
of H_0, and discuss the implications for other cosmological parameters,
including those describing dark energy. I will also discuss the
future prospects of this technique in the era of large sky surveys and
extremely large telescopes.

May 29, 2018

Nicholas Carlini (UCB) “Adversarial Machine Learning”


Many fundamental properties of neural networks are still not well
understood. This talk studies two of these from an adversarial perspective.
I begin with my main line of research and examine the apparently-fundamental
susceptibility of neural networks to adversarial examples. I develop effective
algorithms for generating adversarial examples and find that most most training
regimes are ineffective at increasing robustness. Then, I perform a brief
examination of neural network memorization, and demonstrate that training
data can be efficiently extracted from a trained model given only black-box
access to that model. I conclude with directions for future research.

May 31, 2018

Michael Hance (UCSC) “Searching for Compressed SUSY at the Energy Frontier”


Weak-scale Supersymmetry can help to resolve several puzzles presented by the Standard Model, including the nature of dark matter and the naturalness of the Higgs mass, and has motivated a robust search program at the Large Hadron Collider. Searches for direct production of Supersymmetric partners of weak bosons and leptons are particularly interesting as probes of dark matter and naturalness, but are challenged by small cross sections, low-momentum decay products, and multiple Standard Model backgrounds. I will review efforts by the ATLAS experiment to discover such new particles, with an emphasis on scenarios with “compressed” mass spectra containing nearly-mass-degenerate states. I will discuss recent LHC results, as well as prospects for discovery in Run 2 and beyond.

Jun 04, 2018

Masashi Hazumi (KEK) “LiteBIRD Satellite for Tests of Cosmic Inflation and Quantum Gravity”

Cosmological inflation is the leading hypothesis to resolve the problems in the Big Bang theory.
It predicts that primordial gravitational waves were created during the inflationary era, which
then imprinted large-scale curl patterns in the cosmic microwave background (CMB)
polarization map called the B-modes.

Measurements of the CMB B-mode signals are known as the best probe
to detect the primordial gravitational waves.

LiteBIRD is a candidate for JAXA’s strategic large mission to map the polarization of
the CMB radiation over the full sky at large angular scales with unprecedented precision,
which will offer us a crucial test of cosmic inflation. It will also serve as the first crucial test of
quantum gravity such as superstring theory. Precise polarization maps of LiteBIRD will also
provide us with valuable pieces of information on particle physics and astrophysics.
In this talk, I will give an overview of the science and design of LiteBIRD

Jun 14, 2018

Norbert Zacharias (USNO) “Impact of Gaia on Astrometry and Beyond”

April 2018 marks the 2nd data release (DR2) of the ESA Gaia space mission.
A new era in astrometry begun. Accurate positions, proper motions
and parallaxes for over a billion stars are now available on the
sub-mas level. The properties of DR2 will be explained in context
to pre-Gaia data and the final Gaia results expected in a few years.
The impact of Gaia reaches far into almost all of astronomy, and a
few examples will be given.

Jun 21, 2018

Joshua Spitz (U. Michigan) ” First Measurement of Monoenergetic Muon Neutrino Charged Current Interactions


This talk will present the first measurement of monoenergetic muon
neutrino charged current interactions. The MiniBooNE experiment at
Fermilab has been used to isolate and study 236 MeV muon neutrino
events originating from charged kaon decay at rest. The muon
kinematics and total cross section have been extracted from this data.
Notably, this result is the first known-energy, weak-interaction-only
probe of the nucleus to yield a measurement of omega (energy
transferred to the nucleus) using neutrinos, a quantity thus far only
accessible through electron scattering. I will discuss the
significance of this measurement, and these monoenergetic neutrinos in
general, for elucidating both the neutrino-nucleus interaction and
Slides here

Jun 28, 2018

Adam Becker (UCB) “An Incomplete Survey of Proposed Solutions to the Quantum Measurement Problem”


The central puzzle that drives the field of quantum foundations is the measurement problem: what gives rise to the appearance of wave function collapse? While there is no single answer to this question that has wide acceptance, this is not for lack of available options. A variety of solutions to the measurement problem have been proposed, in the form of various interpretations or modifications of quantum mechanics. Some solutions eliminate collapse entirely, as in the many-worlds and de Broglie-Bohm interpretations. Others propose altering the dynamics of the theory to make collapse objective, as in GRW (stochastic collapse) and gravitational collapse theories. “Psi-epistemic” interpretations attempt to dissolve the measurement problem by claiming that the wave function isn’t something real in itself, but merely a representation of our knowledge of an underlying reality. Finally, Copenhagen-style interpretations claim that that there is no “reality” to be talked about at all. Bounding this menagerie of interpretations are several important theorems that restrict the options available. Bell’s theorem is the most famous (and most misunderstood) of these, but it is not the only one. In this talk, I will briefly lay out the measurement problem and its history, go over several of the theorems that constrain the possible solutions, and discuss a few of the families of quantum interpretations and the open problems that remain for each of them.

Slides here

Jul 10, 2018

Yuri Gershtein (Rutgers U.) “CMS Tracker for HL-LHC: an Exciting New Tool for Discovery”


The radiation environment at the High Luminosity LHC requires CMS to
replace its silicon tracker with one that is more radiation hard and granular.
The new tracker is designed twenty years after the original one, and has new unique
capabilities. It spans 8 units in rapidity, is more then twice lighter, and is capable to
participate in the first level of trigger decisions. In this talk, after sketching the
HL-LHC physics case, I will describe the detector design, FPGA-based track reconstruction,
and focus on one of many possible new opportunities it provides for new physics searches.

Jul 19, 2018

Laura Newburgh (Yale U.) “New Probes of Old Structure: Cosmology with 21cm Intensity Mapping and the Cosmic Microwave Background”


Current cosmological measurements have left us with deep questions about our Universe: What caused the expansion of the Universe at the earliest times? How did structure form? What is Dark Energy and does it evolve with time? New experiments like CHIME, HIRAX, and ACTPol are poised to address these questions through 3-dimensional maps of structure and measurements of the polarized Cosmic Microwave Background. In this talk, I will describe how we will use 21cm intensity measurements from CHIME and HIRAX to place sensitive constraints on Dark Energy between redshifts 0.8 — 2.5, a poorly probed era corresponding to when Dark Energy began to impact the expansion history of the Universe. I will also discuss how we will use data from new instruments on the ACT telescope to constrain cosmological parameters like the total neutrino mass and probe structure at late times.

Slides Here

Sep 06, 2018

Sinead Farrington (U. Warwick) “Physics with Taus”


The identification of hadronically decaying tau leptons at the LHC is challenging. I will review the methods for tau reconstruction at ATLAS and how the identification of tau leptons has enabled several interesting and novel measurements in exotics and Higgs physics at the LHC. I will also look to the future and give some thoughts on next implementations for tau leptons at the LHC.

Sep 20, 2018

Martin White (UCB) “The cosmological legacy of Planck “

The anisotropies in the cosmic microwave background radiation have become our most important cosmological fossil. The study of these “echoes of gravity” has revolutionized cosmology, stringently tested our models and allowed precise measurement of a host of important cosmological parameters. I will discuss how far we’ve come since the early detections of CMB anisotropies and in particular the cosmological legacy of the Planck mission.

Sep 27, 2018

Matt Pyle (UCB) “Athermal Phonon Detectors: World Leading Light Mass Dark Matter Sensitivity From Athermal Phonon Detectors + Preliminary Performance from Large Area Photon Detector for Next Generation Neutrinoless Double Beta Decay Experiments”

In this talk, we present the new world leading results from the first search of the SuperCDMS collaboration for inelastic electronic recoils from low mass dark matter dark matter (500keV – 100MeV) using our new single ionization sensitive cryogenic calorimeters.
We’ll also present preliminary performance of a large area cryogenic photon detector with applications in light mass dark matter and neutrinoless double beta decay. With 3eV sensitivity and 20us pulse rise time, it well surpasses all technical requirements for next generation cryogenic neutrinoless double beta decay experiments.

Oct 04, 2018

Kyle Helson (NASA Goddard) “The Status and Outlook of Cosmic Microwave Background Polarization Measurements”


The detailed characterization of the intensity and polarization Cosmic Microwave Background (CMB) radiation provides a powerful tool to constrain the properties of early Universe. The polarization induced by a stochastic gravitational wave background in this epoch induces a distinctive and measurable signature of primordial inflationary processes. Presently the field has a healthy contingent of ground, balloon, and space based missions. In this talk I will discuss a brief history of CMB measurements, the current status of the field and outlook for the future. I will also discuss on-going work at NASA Goddard Space Flight Center on the development of polarization-sensitive detectors for a future satellite CMB polarization mission and their application in ground based instruments.

Oct 11, 2018

Qian Xin (BNL) “Development of LArTPC for Neutrino Physics”


Liquid Argon Time Projection Chamber (LArTPC), with its mm-scale position resolution and the full-active-volume imaging-aided calorimetry, is an excellent device to detect accelerator neutrinos at GeV energy range. This technology may hold the key to search for new CP violation in the lepton sector, to determine the neutrino mass hierarchy, to precisely measure neutrino mixing parameters, to search for baryon number violation, and to search for sterile neutrino(s). In this talk, I will review the current status of the detector development. In particular, the challenges in TPC signal processing and event reconstruction will be discussed among other subjects.

Oct 18, 2018

Ning Bao (UCB/LBNL) “Quantum Information and Quantum Gravity”


There has been much recent interest at the intersection of the fields of Quantum Information and Quantum Gravity. In this talk, I will go over some of the motivating principles/important work that has been done in this area, and explain some current research promising research trends.

Oct 23, 2018

Matthias Neubert (U. Mainz) “Effective Field Theory after a New-Physics Discovery”


When a new heavy particle is discovered at the LHC, it will be interesting to study its decays into Standard Model particles using an effective field-theory framework. We point out that the proper effective theory must be based on non-local operators defined in soft-collinear effective theory (SCET). For the interesting case where the new resonance is a gauge-singlet spin-0 boson, which is the first member of a new sector governed by a mass scale M, we show how a consistent scale separation between M and the electroweak scale v is achieved up to next-to-next-to-leading order in \lambda~v/M. The Wilson coefficients in the effective Lagrangian depend in a non-trivial way on the mass of the new resonance and the masses of yet undiscovered heavy particles. Large logarithms of the ratio M/v can be systematically resummed using the renormalization group. We develop a SCET toolbox, with which it is straightforward to construct the relevant effective Lagrangians for new heavy particles with other charges and spin.

Oct 25, 2018

Laura Newburgh (Yale U.) ” Forefronts of Cosmology: Beyond Standard Model Physics with Upcoming CMB Instruments”


Upcoming new instruments to measure the polarized CMB promise to provide discriminatory limits on inflation, the number of light relic particles, and the sum of the neutrino masses, ushering in a new era of using the CMB as a probe of particle physics. Achieving these science goals requires highly sensitive instruments that are composed of enormous arrays of low noise detectors. In addition, systematic errors and foreground removal must be improved to lower the systematics floor below the statistical errors, necessitating dramatic improvements in calibration precision. In this talk, I will describe Simons Observatory (coming online in ~2021) and CMB-S4 (coming online in ~2027), their science goals, and how the twin requirements for sensitivity and systematics require a new approach to software for readout, data acquisition, and control systems. I will also discuss future directions for cosmology, including work in 21cm instruments to improve our understanding of the nature of Dark Energy.

Oct 30, 2018

Caterina Vernieri (Stanford) “Higgs to Beauty Quarks: First Observation of the Big Missing Piece”


The Higgs boson discovery at the LHC marked a historic milestone in the study of fundamental particles and their interactions. Over the last six years, we have begun measuring its properties, which are essential to build a deep understanding of the Higgs sector of the Standard Model and to potentially uncover new phenomena. The Higgs’ favored decay mode to beauty (b) quarks (~60%) had so far remained elusive because of the overwhelming background of b-quark production due to strong interactions. Observing the Higgs decay to b-quarks was one of the critical missing pieces of our knowledge of the Higgs sector. Measuring this decay is a fundamental step to confirm the mass generation for fermions and may also provide hints of physics beyond the Standard Model. The CMS observation of the decay of the SM Higgs boson into a pair of b-quarks exploiting an exclusive production mode (VH) is yet another major milestone. This experimental achievement at the LHC, considered nearly impossible in the past, makes use of several advanced machine learning techniques to identify the b-quark distinctive signature, improve the Higgs boson mass resolution, and discriminate the Higgs boson signal from background processes.

Nov 01, 2018

Vivian Poulin (JHU) “Shedding Light on Dark Matter with the CMB: Implications for EDGES 21cm Signal”


In this talk, I would like to review how the Cosmic Microwave Background (in particular its temperature and polarization anisotropies) can be used to perform both direct and indirect detection of Dark Matter.  In a first part, I will show how the CMB can be used to put stringent constraints on DM models leading to energy injection, such as DM annihilations and decay or Primordial Black Holes matter accretion. I will compare CMB bounds to those coming from galactic cosmic and gamma ray searches and illustrate how the 21cm signal, a major target of next generation surveys, can be used to significantly improve over current limits. In a second part, I will discuss a recent puzzling absorption feature in the global 21cm signal observed by the EDGES experiment. Such feature could be explained by efficient scattering between DM and baryons in the late universe. I will show how the CMB strongly challenges such explanation of that signal.

Nov 06, 2018

Guy Ron (Jerusalem) “The Proton Radius – Old Measurements and New Ideas”


The radius of the proton, generally assumed to be a well measured and understood quantity has recently come under scrutiny due to highly precise, yet con?icting, experimental results. These new results have generated a host of interpretations, none of which are completely satisfactory.

I will discuss the existing results, focusing on the discrepancy between the various extractions. I will brie?y discuss some theoretical attempts at reso-lution and focus on new scattering measurements, both planned and already underway, that are attempting to resolve the puzzle

Nov 08, 2018

Lucie Tvrznikova (Yale) “Sub-GeV dark matter searches and electric field studies for the LUX and LZ experiments “


The Large Underground Xenon (LUX) and the LUX-ZEPLIN (LZ) detectors were designed to directly observe the interaction of dark matter (DM) with xenon target nuclei and thus probe much of the unexplored DM parameter space. I will discuss two novel direct detection methods, Bremsstrahlung and the Migdal effect, that were used by LUX to place limits on DM with masses of 0.4-5 GeV. I will also describe the development of a fully 3D model of electric fields that varied during the detector’s final 332 live-days of data acquisition. Since direct measurement of electric fields was not possible, this work enabled a thorough understanding of the detector throughout its operation. Lastly, I will present new results from the Xenon Breakdown Apparatus (XeBrA) built at LBNL to characterize the dielectric breakdown under high voltage in liquid xenon and liquid argon. Results from XeBrA will inform LZ and the future of noble liquid detector engineering.

Nov 13, 2018

Christian Herwig (U. Pennsylvania) ” Targeting natural supersymmetry with top quarks”

What is the roadmap for the discovery of new physics in the
post-Higgs-observation era? The concept of naturalness can provide a
useful guiding principle, considering the interplay between new, heavy
physics and the electroweak scale. I will describe a new search for
natural models of supersymmetry from the ATLAS experiment via the
production of light top squarks. I will also discuss the impact of
precision top-quark measurements on future searches, highlighting a
recent measurement of quantum interference in top-quark production.

Nov 15, 2018

Stephane Brunet Cooperstein (Princeton) “Observation of Higgs Boson Decay to Bottom Quarks by the CMS Experiment”


Since the discovery of the Higgs boson six years ago, great progress has been made in measuring precisely its properties. These measurements have primarily been made via rare Higgs boson decays to two photons or two Z bosons due to their distinct experimental signatures. Although 60% of the Higgs bosons are predicted to decay to bottom quarks, it was not originally expected to observe this Higgs boson dominant decay mode until much later in the LHC program due to an overwhelming background of bottom quarks produced via strong interactions. This milestone observation was achieved this summer by both the ATLAS and CMS experiments at the LHC. This seminar presents the observation of the Higgs boson decay to bottom quarks by the CMS experiment, with an emphasis on the latest results using data collected in 2017. The observation was made possible by incorporating deep learning techniques and novel analysis methods. This constitutes the first observation of a Yukawa coupling to down-type quarks. Moreover, it demonstrates the feasibility of the first precision measurements of Higgs bosons in the VH production mode in the near future.

Nov 20, 2018

Jesse Liu (U. Oxford) “Opening New Frontiers for Supersymmetry and Dark Matter at the LHC”


Smoking gun signals for new physics at the LHC elude us.
What gaps remain under the lamppost? Where do we focus the next
generation of searches? This talk tackles these pressing problems by
highlighting new frontiers opened by recent theoretical surveys,
extending ATLAS beyond its design capability, and state-of-the-art
analysis strategies. Sensitivity to key supersymmetry targets
motivated by naturalness and WIMP dark matter are just surpassing two
decade old LEP limits. Striking blind spots remain around 100 GeV mass
scales that invite creative discovery strategies for future efforts.

Nov 27, 2018

Elodie Deborah Resseguie (U. Pennsylvania) “Electroweak SUSY Searches on ATLAS”


Supersymmetry (SUSY) gives a solution to the naturalness problem of the Standard Model (SM) while providing a candidate for dark matter, solving two mysteries in modern physics. As the LHC collects more data and sets strong constraints on SUSY in the strong force sector within reach of the collider, new SUSY particles produced by electroweak (EWK) processes remain significantly less unconstrained. The EWK production of SUSY particles can be observed by their decay via the W and Z gauge bosons to final states with two or three leptons and missing transverse momentum from invisible particles. Two SUSY models are considered: one with a Wino next-to-lightest SUSY particle (NLSP) and Bino LSP, motivated by dark matter, and another with a Higgsino LSP, motivated by naturalness. The Higgsino LSP models are particularly challenging due to the small mass, or “compressed”, splittings, leading to low energy W and Z bosons. This requires specialized techniques for triggering, optimizing, and estimating backgrounds. I will present the latest ATLAS searches for both models, including the first result for Higgsino production since LEP, as well the outlook for future studies.

Nov 29, 2018

Karri DiPetrillo (Harvard U.) “Searching for long-lived particles with displaced vertices in ATLAS “


Most searches for new physics at the Large Hadron Collider assume that a new particle produced in pp-collisions decays almost immediately, or is non-interacting and escapes the detector. However, a variety of new physics models predict particles which decay inside the detector at a discernible distance from the interaction point. Such long-lived particles would create spectacular signatures and evade many prompt searches. In this talk I will focus on a search for long-lived particles in events with a displaced vertex and a muon. I will also discuss challenges for the Muon Spectrometer in the face of increasing LHC luminosity.  

Dec 04, 2018

Danielle Norcini (Yale) “PROSPECTing for reactor neutrinos at short baselines”


Experiments at nuclear reactors have played a key role in determining the properties of the weakly-interacting neutrinos. PROSPECT is a next-generation experiment studying reactor neutrinos at very short baselines (< 10m) in an environment with limited shielding from cosmogenic backgrounds. Commissioned in March 2018, the compact, segmented detector unambiguously observed neutrinos in its first 2 hours of operation. In the months following, PROSPECT has performed a world-leading search for “sterile” neutrino oscillations and made the world-leading measurement of the uranium-235 antineutrino energy spectrum. This talk will detail the detector design, construction, and first physics results.

Dec 11, 2018

Scott Haselschwardt (UCSB) ” Expected Performance of the LZ Outer Detector and a Radioassay of its Gadolinium-Loaded Liquid Scintillator”


The LZ (LUX-ZEPLIN) experiment is a second generation direct dark matter detector under construction at the Sanford Underground Research Facility (SURF) in Lead, South Dakota, USA. LZ will use a 7 tonne central liquid xenon target, arranged in a dual-phase time projection chamber (TPC), to seek evidence for nuclear recoils from a hypothesized galactic flux of weakly interacting massive particles (WIMPs). Surrounding the LZ TPC will be an outer detector (OD) consisting of 17.3 tonnes of LAB-based gadolinium-loaded liquid scintillator (GdLS). The OD’s primary functions will be to tag neutron single-scatter events in the liquid xenon which could mimic a WIMP dark matter signal and to characterize the radiation environment of LZ. In this talk, I summarize the expected performance of the OD and report on the design and results of the “Screener”, a small liquid scintillator detector consisting of ? 23 kg of the GdLS to be used in the OD. The Screener was operated in the ultra-low-background environment of the former LUX water shield in the Davis Laboratory at SURF for radioassay of the GdLS. Careful selection of detector materials and use of ultra-low-background PMTs allows the measurement of a variety of radioimpurities. In particular, the 14C/12C ratio in the scintillator is measured, while the use of pulse shape discrimination allows the concentration of isotopes throughout the 238U, 235U, and 232Th chains to be measured by fitting the collected spectra from ? and ? events. The GdLS is found to meet the requirements for LZ, however, more aggressive purification is being implemented for the final GdLS product that ensures the OD will successfully carry out its role in the hunt for WIMP dark matter.

Dec 13, 2018

Brooke Russell (Yale) “Leveraging LArTPC Technology to Definitively Resolve the MiniBooNE Anomaly – An Elctron Neutrino Appearance Search at MicroBooNE”


MicroBooNE is a single-phase liquid argon time projection chamber (LArTPC) short-baseline accelerator neutrino experiment located at Fermilab on the Booster neutrino beamline. MicroBooNE’s foremost scientific objective is to address the low energy excess of single shower electromagnetic events seen by the precursor MiniBooNE experiment. Leveraging the fine-grained drifted ionization charge signal from particle interactions, LArTPCs provide detailed topological and calorimetric information for physics analyses. By capitalizing on the interplay between scintillation light and 3D ionization charge imaging, a high efficiency, low background analysis is in development to address MiniBooNE’s anomalous result. The status of this analysis is described.

Dec 20, 2018

Sunny Vagnozzi (Stockholm University) “Recent Developments in Neutrino Cosmology”


A robust detection of neutrino masses is avowedly among the key goals of several upcoming Cosmic Microwave Background (CMB) and Large-Scale Structure (LSS) surveys. In this talk, I will describe recent progress in neutrino cosmology on three fronts. Firstly, I will illustrate the wealth of information on the sum of the neutrino masses obtainable from current cosmological probes, focusing on LSS data. Current upper limits begin favoring the normal neutrino mass ordering, emphasizing the need to develop statistical tools for quantifying this preference. Next, I will discuss galaxy bias as a limitation towards fully capitalizing on neutrino information hidden in LSS data, proposing a method for calibrating the scale-dependent galaxy bias using CMB lensing-galaxy cross-correlations. Moreover, in massive neutrino cosmologies the bias as usually defined is scale-dependent even on large scales: neglecting this effect will lead to incorrectly inferred parameters. Finally, I will take on a different angle and discuss degeneracies between neutrinos and other cosmological parameters. I will show how in certain physically motivated dynamical dark energy models the neutrino mass upper limits tighten instead of broadening, discussing implications for future laboratory determinations of the mass ordering. I will also discuss how neutrino unknowns affect constraints on inflationary models.