List of past RPMs — 2021

Jan 05, 2021

Xinran Li (Princeton University) “The energy resolution and the energy deposition processes in noble liquid dark matter detectors”

Noble liquid detectors, especially liquid argon and liquid xenon time projection chambers (TPCs) have been developed and improved during the last decades. They produced the best limits in the search for one of the best motivated dark matter candidates, weakly interacting massive particles (WIPMs), in the O(10)GeV to O(10)TeV mass region. Ill first talk about the DarkSide-50 low mass analysis which produced the best limit of 5$\times$10^{-42} cm^2 on spin-independent dark matter nuclear scattering cross section for dark matter masses around 3 GeV. The detector energy resolution around the analysis threshold strongly affects the shape of the limit curve in the low mass region. One main contribution to the energy resolution comes from the intrinsic fluctuations during the energy deposition processes, including the quenching processes and the charge recombination, in noble liquids. Extending to different materials, I’ll also mention the scintillation in xenon doped liquid argon, and the recombination in amorphous selenium. The energy resolution can be improved with sensitivity to the quenched heat energy. Superfluid helium 4 detectors have been proposed to probe nuclear recoil dark matter masses as low as O(10)MeV with current technology. The compatibility with phonon sensors permits sensitivity to all energy deposition channels in superfluid helium.


Dylan Temples (Northwestern University) New Directions in Liquid Noble Dark Matter Searches: Probing the Sub-GeV Regime


The most sensitive searches for dark matter (DM) with mass above ~10 GeV/c2 use the dual-phase xenon time-projection chamber (LXe-TPC) technology. In the U.S., development of this technology is spearheaded by the LUX-ZEPLIN experiment, with first science data coming soon. As these detectors increase in scale and sensitivity, previously negligible backgrounds become important to understand, both to prevent false discovery claims and to accurately measure the ultimate DM sensitivity of such an experiment. In this talk, I will discuss one class of such backgrounds: neutrinos scattering from the inner-shell electrons of a xenon atom. This process has heretofore gone uncalibrated, and due to its distinct event topology, is more akin to a nuclear recoil (potential DM signal) than an electron recoil (background). I will also discuss two liquid-noble technologies for searching for dark matter below ~5 GeV/c2: light-element doping, and superfluid helium detectors. Doping an LXe-TPC with low concentrations of light elements, such as hydrogen, enables sensitivity to dark matter models with mass down to 20 MeV/c2 while simultaneously probing spin-dependent DM-nucleon coupling. Superfluid helium detectors offer a complementary DM search avenue, as it is more sensitive to low-mass spin-independent DM than hydrogen-doping, but cannot investigate spin-dependent coupling.

Jan 12, 2021

Digvijay Wadekar (New York University) “Accelerating analysis of cosmological surveys with novel analytic methods and machine learning”

– Abstract: 
In order to infer cosmological parameters from data of upcoming surveys like DESI, we will use summary statistics such as the power spectrum. An accurate estimate of their covariance matrix is crucial for the inference analysis. The traditional process of obtaining the covariance involves thousands of expensive mock simulations. I will present a novel analytic approach to calculate the covariance which is faster by more than four orders of magnitude. I will demonstrate the validation of our analytic approach with an analysis of the BOSS DR12 data and also show that it helps reduce the systematic error budget of cosmological constraints, thus making our approach useful for upcoming high-precision surveys like the Rubin observatory and DESI. 
In the second part of my talk, I will present machine learning methods to emulate expensive hydrodynamical simulations and make cheap and accurate synthetic catalogs, which are needed for modeling non-linear scales in galaxy and line intensity mapping surveys.

Jan 13, 2021

Etienne Dreyer (Simon Fraser University) Searching for new physics using high-energy lepton pairs and some other hot topics in ATLAS

What is the nature of dark matter? What leads to the fundamental forces having such disparate strengths? Can we explain the small mass of the Higgs boson without excessive fine tuning? These outstanding questions are part of a broad motivation to continue investigating new physics scenarios beyond the Standard Model (SM). Several theoretical solutions propose an extended gauge symmetry group beyond the SM, and hence predict the existence of additional massive gauge bosons. I will discuss the latest search for a new neutral boson producing the particularly clean signature of two high energy leptons in the ATLAS detector.

In the second part of the talk I will share my ambitions for ongoing and future research in machine learning applications to particle physics, testing the SM in strategic connections to the Higgs boson, and work on the ATLAS Inner Tracker (ITk) upgrade.

Jan 14, 2021

Nandita Khetan (Gran Sasso Science Institute) “Cosmology in the multi-messenger era”

The talk will present my PhD project research which focuses on advancing the standardization of various transients to be used as cosmological probes and the evaluation of the Hubble constant (H0). With SN Ia, I will present interesting results coming from a recent work where I used an alternate way to calibrate SN Ia based on the surface brightness fluctuations (SBF) method. Besides SNe Ia, I explored other exotic/new transients like Superluminous supernovae, Kilonovae and Gravitational waves as distance indicators. In particular, I worked on SLSNe in rest frame UV wavelengths to find peak luminosity correlations with light curve properties. I participated in a project exploring KNe as a standard candle to perform independent measurements of H0. I am currently working on the prospects of calibrating SNe Ia with GW distances measured from future GW detectors. I will briefly present these cosmological probes and discuss their future perspectives.

Jan 19, 2021

Special RPM-Berkeley Cosmology Seminar | Sihan Yuan (Harvard University) Tackling the challenges of galaxy-dark matter connection modeling and secondary bias

Modeling galaxy-dark matter connection is essential in deriving unbiased cosmological constraints from galaxy clustering observations. We show that a more physically motivated galaxy-dark matter incorporating secondary biases can result in more accurate predictions of galaxy clustering, and that it significantly reduces the tension in galaxy lensing. We further present progress in building a galaxy-dark matter connection framework that is rich in features and highly efficient in evaluation, enabling more robust cosmological analyses with upcoming DESI data.

Jan 19, 2021

Kevin Woods (Stony Brook University) “Measuring neutrino oscillations with accelerator-based, long-baseline experiments”


Accelerator-based, long-baseline neutrino oscillation experiments are uniquely positioned to explore the CP-violating nature of the neutrino sector. This talk will briey discuss the experimental technique before surveying selected topics spanning both current and future generations of such experiments. First, the Bayesian Markov Chain Monte Carlo oscillation analysis of the T2K experiment, which has been accumulating data for the past 10 years, will be presented before discussing the ongoing efforts to extend the analysis framework to be used in a joint analysis between T2K and the NOA experiment at Fermilab. The experience obtained from these experiments already in the data taking stages has been and will continue to be invaluable in the design of future experiments, such as the Deep Underground Neutrino Experiment (DUNE). The DUNE collaboration will employ the liquid argon time projection chamber (LArTPC) technology at an unprecedented scale to measure neutrino interactions at its far site. The talk will conclude with an overview of the realization and operation of the protoDUNE-SP detector, a prototype for a DUNE far detector module, for a charged particle test beam run that took place at CERN in the end of 2018

Jan 21, 2021

Kathryn Sutton (Columbia University Department of Physics) “MicroBooNE’s Search for a Photon-Like Low Energy Excess”

MicroBooNE is a Liquid Argon Time Projection Chamber (LArTPC) detector and is the first of three such detectors to be commissioned as part of the Short Baseline Neutrino (SBN) program at Fermilab (FNAL), and has been taking data since 2015. One of its primary goals is to investigate the unexplained excess of electromagnetic events in the lowest energy ranges observed in the same neutrino beamline at the MiniBooNE experiment. While one leading interpretation of this anomaly is electron neutrino appearance due to sterile neutrino oscillations, a viable Standard Model explanation is neutrino-induced single photon events. The MicroBooNE single photon analysis looks to test this interpretation by measuring the rate of neutrino-induced resonant neutral current (NC) delta baryon production and subsequent delta radiative decay with a single photon in the final state, NC ??N?. This measurement of a process that has never been observed before is projected to improve upon the current experimental limit from T2K by greater than a factor of thirty. This talk will present the status of the MicroBooNE single photon search, as well as ongoing work to create a more complete picture of single photon production in the SBN program.

Jan 26, 2021

SPECIAL RPM-Berkeley Cosmology Seminar | Noah Weaverdyck (University of Michigan) “Controlling Systematics in Large-Scale Structure Surveys”

Large-scale structure (LSS) surveys have exploded in size over the last few decades, cataloguing the locations and shapes of hundreds of millions of galaxies. The unprecedented precision enabled by such datasets puts extraordinary demands on the control of systematic errors. In this talk, I will discuss how extracting information from LSS surveys is complicated by systematics that enter the survey selection function, outline several approaches to address these systematics, and highlight important lessons for upcoming surveys.

Jan 26, 2021

Vinicius Mikuni (University of Zurich) “Machine learning as a tool for Standard Model measurements.”

The Standard Model of particle physics described the interactions between the elementary particles that compose our universe. To study these interactions, protons collide at very high energies at the Large Hadron Collider, generating hundreds of particles through every bunch crossing. In this talk, I will present two measurements that probe different aspects of the Standard Model: the determination of the ttbb and bbH(bb) cross sections. I will show the challenges faced during data analysis and how modern machine learning methods can be used to improve the precision of these measurements.

Jan 27, 2021

Elliott Reynolds (University of Birmingham) “Searching for New Physics using the Higgs Boson and Machine Learning”

The Higgs boson is the only fundamental spin-0 particle in the Standard Model (SM) of particle physics, associated with an ever-present field that is the source of mass and linked to electroweak symmetry breaking, making it a particle like no other. Its mass and spin provide us with the strongest indication yet that something is amiss with the SM, and offer a unique window to probe the SM and new physics in its decays. This talk covers a broad range of searches sensitive to new physics in the Higgs sector using the ATLAS detector at the CERN LHC, with an emphasis on the versatile role of novel machine learning techniques. The related physics prospects of the high-luminosity upgrade of the LHC and the ATLAS detector are also discussed.

Jan 28, 2021

Florian Bernlochner (Bonn) “Fantastic Bs and where to find them! “


The Belle II Experiment is a next generation SuperB factory that aims to discover new physics phenomena at the highest intensities. It started its first physics run in 2019 and will until the end of 2021 collect a data set comparable to what the previous B-Factory experiments recorded during a decade-long run. I will review the current status, point out the contributions my group is strongly involved in, and provide an outlook for the summer conferences 2021.

Jan 28, 2021

Mariel Pettee (Yale University) “The Search for VH (V ? Leptons, H ? ??) with the ATLAS Experiment in Run 2”

As part of a comprehensive plan to investigate the many combinations of production and decay of the Standard Model Higgs boson using the full Run 2 ATLAS dataset at the LHC, I will present a search for the SM Higgs boson produced in association with a leptonically-decaying vector boson (i.e. a W or Z boson) and decaying into a pair of tau leptons. Efficient identification of hadronically-decaying tau leptons at the trigger level is essential to this analysis, so I will also discuss my technical work in deploying an RNN-based tau identification scheme in the ATLAS High-Level Trigger (HLT) in Run 2. Lastly, I will show highlights of my independent AI work in leading teams of researchers across academia and industry to pioneer the state-of-the-art in AI-generated choreography using techniques including Variational Autoencoders (VAEs) and Graph Neural Networks (GNNs).

Feb 02, 2021

SPECIAL RPM-Berkeley Cosmology Seminar | Anton Baleato Lizancos (University of Cambridge) “Fundamental Physics with CMB Lensing and Delensing: the Good, the Bad and the Systematics”

Gravitational lensing of CMB photons by the matter distribution of the Universe can be both a blessing and nuisance. It’s a blessing because of the way it can be harnessed to map the structures responsible for the deflections, and from this, constrain any physics affecting the growth of cosmic structure, such as the sum of the neutrino masses or dark matter. But lensing is also a nuisance because it generates B-mode polarization which obscures the highly-sought-after primordial signal associated with gravitational waves generated during cosmic inflation, our most accessible portal to physics near the GUT scale. In this talk, I will focus on key systematic effects that need to be controlled in order to harness the full potential of the Simons Observatory (SO), CMB-S4, and other upcoming experiments to make progress in these exciting areas.

In the first part of my talk, I will briefly review the ways in which emission from galaxies and clusters can bias power spectra and cross-correlations of CMB lensing reconstructions, and describe our ongoing efforts to understand these biases analytically. Then, in the second part, I will explain how the lensing contamination to CMB B-modes can be removed what is known as delensing and discuss our recent findings regarding the performance of different delensing methods. I will also summarize preparatory work to delens SO data, and highlight biases to watch out for (and how to mitigate them) when the matter proxy used for delensing is either the cosmic infrared background or a lensing reconstruction derived from the CMB itself.

Feb 02, 2021

Nitish Nayak (University of California, Irvine) “Ghostbusters : Estimation of Neutrino Oscillation Parameters by the NOvA Experiment”

The discovery of neutrino oscillations provides the first indication of a lepton flavor violating (LFV) process, one that isn’t predicted by the Standard Model. Extending the Standard Model picture to account for this usually proceeds via the addition of new mass terms, either Dirac or Majorana in nature or both, to the Standard Model Lagrangian. Probing the LFV process by characterizing the strength of neutrino oscillations is therefore fundamental to understanding the nature of neutrino masses. In addition, there is a possibility that neutrino oscillations are CP-violating which can provide hints about the observed matter-antimatter asymmetry in the universe. The NOvA experiment at Fermilab was designed to be sensitive to such questions by measuring some of the key parameters governing oscillatory behaviour. It detects neutrinos (antineutrinos) using an intense beam of predominantly muon-neutrinos (muon-antineutrinos) from the NuMI facility at Fermilab. It does this by housing two detectors, a 1-kiloton Near Detector near the beam source and a massive 14-kiloton Far Detector, 810 km away, near the Canadian border. The measurement of neutrino oscillation parameters is performed by examining the neutrino beam and the simulation at the Near Detector and then observing how many neutrinos have oscillated by the time they reach the Far Detector. This is a challenging analysis highlighted by the fact that only a handful of oscillated events are observed at the Far Detector every year. This is made worse by the fact that the Far Detector is placed on the surface, thus collecting an enormous amount of cosmic background (at a rate of $\sim$ 10 kHz). In this talk I will therefore provide an overview of how this measurement is performed and some of the key problems we wrestle with. These problems can be statistical, computational and even theoretical and so I will put particular emphasis on the methodologies used in overcoming them.

Feb 11, 2021

Geoff Penington (UCB) “Replica Wormholes, Entanglement Wedges and the Black Hole Information Paradox”


Hawking famously argued, based on semiclassical calculations, that the radiation from evaporating black holes is contains no information about the matter that fell in. This would be inconsistent with the unitarity of quantum mechanics. In this talk, I will show that, in more careful replica trick calculations, the gravitational path integral becomes dominated at late times by saddles containing spacetime wormholes. These wormholes cause the entropy to decrease after the Page time, consistent with unitarity, and allow information to escape from the interior of the black hole.

Mar 11, 2021

David Weinberg (OSU) “Cosmology Past, Present, and Future”

David Weinberg (OSU)
“Cosmology Past, Present, and Future”
I will give a broad overview of the current state of observational cosmology, with historical context and an eye to the future.  Developments over the past three decades have led to a standard cosmological scenario that is remarkably successful at explaining a wide array of high precision measurements.  However, this scenario leaves several big questions at best partially answered.  What is dark matter?  Why is the expansion of the universe accelerating?  What is the physics of inflation and the
origin of the universe?  I will discuss observational tensions that hint at cracks within the standard model, and I will discuss ongoing and upcoming experimental efforts that aim at order-of-magnitude increases in measurement precision with the hope of revealing vital new clues about the physics of the cosmos.

Mar 18, 2021

Federico Meloni (DESY) Hunting Wino and Higgsino Dark Matter at the Muon Collider


Events containing disappearing tracks originating from the decay of a heavy and electrically charged long-lived particle to a pair of undetectable particles are key to the discovery of compelling minimal dark matter models at collider experiments. This talk will present the prospects for a search for such experimental signature at a future muon collider. Techniques dedicated to the suppression of the backgrounds induced by the in-flight decays of the muon beams will be presented and the results compared to other future collider experiments in the context of MSSM higgsino and wino dark matter. In particular, this talk will show how a muon collider operating at a centre of mass energy of 10 TeV can rival, and in some cases outperform, the sensitivity of a 100 TeV proton proton collider.

Mar 25, 2021

Timon Heim (LBNL) “Moving from the Prototyping to the Production Phase for the Inner Tracker Upgrade of the ATLAS Detector”

As part of the Phase 2 upgrade of the ATLAS detector to ready it for operation at the High-Luminosity LHC the inner tracking system will be replaced by an all silicon Inner Tracker (ITk). The Pixel and Strip system of the ITK are now leaving the prototyping phase and preparing the start of the (pre) production phase. As part of this transition I plan to report on the latest status of the detector design and retrospectively discuss major design decisions which shaped the detector as it is now planned to be produced. In addition to looking at the latest tracking detector instrumentation, the scale of the ITk Pixel and Strip detector allows us to look at what challenges we might face for future equally sized or larger tracking detectors.

Apr 08, 2021

Louise Skinnari (Northeastern)   Track-triggering at CMS for the High-Luminosity LHC  


?The high luminosity upgrade of the Large Hadron Collider (LHC), scheduled for 2025-2027, will significantly increase the instantaneous luminosity of the LHC collisions. The resulting large proton-proton collision datasets will allow precise measurements of Higgs? boson? properties, searches for ?very ?rare processes, and much more. To cope with the challenging ?experimental ?environment ?resulting ?from the high luminosity, significant upgrades will be required for the LHC ?detectors. A key upgrade of the CMS ?detector is to incorporate the identification of charged particle trajectories in the hardware-based trigger system, with potential to not only solidify the ?CMS ?trigger strategy but to enable ?searches for ??completely new physics ?signatures. This seminar will discuss the motivation of the CMS track trigger, give an overview of the system, and discuss its expected performance based on simulation? and hardware demonstration??.

Apr 15, 2021

Jamie Boyd (CERN)  The FASER Experiment at the CERN LHC: Looking Forward to New Physics

The Forward Search Experiment (FASER) is the newest experiment at the LHC, approved in 2019 and recently installed into the CERN LHC complex. It is a small and inexpensive experiment placed 500 meters downstream of the ATLAS interaction point. FASER is designed to capture decays of exotic particles, produced in the very forward region, out of the ATLAS detector acceptance. In addition, FASERnu, a FASER sub-detector, is designed to detect collider neutrinos for the first time and study their properties. This seminar will present the physics prospects, the detector design, and the construction and installation progress of FASER.

Apr 20, 2021

Alberto Lusiani (INFN)  “Muon magnetic anomaly measurement to 0.46 ppm at FNAL”


The Dirac equation predicted that the g-factor of spin 1/2 particles be 2, but in 1948 Julian Schwinger calculated that quantum electrodynamics (QED) fluctuations increase the electron and muon g-factor such that the anomaly a_(?)?=?(g_(?)???2)/2?=??/2? at first order. Since then, many theorists have estimated an increasingly larger amount of Standard Model contributions to a_(?), and in 2020 an international collaboration of theoretical and experimental physicists (Muon g-2 Theory Initiative) has published a Standard-Model-based prediction of a_(?) with a 0.37 ppm precision, using the available information and calculations. The theory prediction uncertainty is dominated by the hadronic contributions, which have been primarily estimated using measurements of hadronic processes with dispersive techniques.

The muon magnetic anomaly a_(?)?=?(g_(?)???2)/2 has been measured since 1959 at CERN, and the current 0.54 ppm precision world average has been published in 2006, using data collected at BNL in the years 1997-2001.

While the electron magnetic anomaly is measured and predicted with about three orders of magnitude better precision, the muon magnetic moment test of the Standard Model is more sensitive to hadronic effects and to most hypothetical New Physics contributions because the muon mass is about 200 times larger than the electron one. The sensitivity of the muon anomaly measurement extends to many New Physics effects that are searched in high energy experiments.

After a 3-years long analysis of data collected in 2018 at FNAL, the Muon g-2 collaboration has completed a measurement of the muon magnetic anomaly with a slightly improved precision of 0.46 ppm. The updated world average has a precision of 0.35 ppm and differs from the theory prediction by 4.2 standard deviations. We describe how the measurement has been performed by measuring the muon precession frequency is a storage ring and the magnetic field experienced by the muons and how the new world average has been computed. The precession frequency measurement dominates the uncertainty and has been completed by 6 independent groups with 4 different methods, obtaining consistent results. The data analysis has been performed in a blind way with a
special care for the internal consistency and the estimation of systematic biases and uncertainties.

The Muon g-2 collaboration aims at reducing the statistical uncertainty by a factor 2 in about 18 months from now, using data already collected, and eventually aims at collecting a total of about 20 times the statistics of the BNL data, to reach an ultimate precision of 0.14 ppm (0.10 statistical and 0.10 systematic).

Apr 22, 2021

Michael Peskin (SLAC) ” A Gamma-Gamma Collider for Multi-10-TeV Physics”


It is time to start thinking about the next-next generation of colliders, that is, colliders that access the multi-10-TeV region of parton center of mass energies. The discussion has already begun with consideration of FCC-hh and muon colliders, but those technologies are not here yet, and there is room for additional proposals. One that is interesting to me is plasma wakefield acceleration of electrons and conversion to a gamma-gamma collider. In this talk, I will discuss possible schemes for this, and technical and physics questions for the proposal that need to be addressed.

Apr 27, 2021

SPECIAL RPM | Joint Nuclear Science and Physics Division Seminar on muon g-2

Joint Nuclear Science and Physics Division Seminar on muon g-2

Tuesday, April 27, 10:30am – 12:45pm

Zoom Meeting Link

Meeting ID: 927 0993 8569

Passcode: 843893

We are having a special seminar followed by a panel discussion on the recent g-2 result for the muon, with an emphasis on the theoretical prediction for this quantity.

10:30am : Welcome

10:35am: Kálmán Szabó

11:05am: Martin Hoferichter

11:40am: Panel discussion + audience question/answer

Panelists: Gilberto Colangelo (chair), Aida El-Khadra, Christoph Lehner, Bill Marciano and Thomas Teubner

Apr 29, 2021

Martin Savage (University of Washington) “Quantum Simulations for HEP and NP”

Theoretical predictions of the properties and dynamics of quantum many-body systems of importance to  High-energy and nuclear physics research are anticipated to require, in many instances, beyond classical computational resources.  Such systems may be amenable to quantum simulations in the future, and the very first steps are now being taken towards these objectives. I will discuss the potential and status of this newly emerging area, with a focus on field theories.


May 06, 2021

Xiaosheng Huang (USF) “Strong Gravitational Lenses Discovered in the DESI Legacy Imaging Surveys”

ABSTRACT:We have discovered over 1500 new strong lensing candidates in the Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Surveys using residual neural networks.  The photometric redshifts of the candidate lenses are broadly distributed between 0.1 and 1.  Follow-up observations are underway.  Our Hubble Space Telescope SNAP program has confirmed all 47 of the candidates observed so far and our DESI Secondary Targets program for Year 1 will likely observe ?400 candidate systems.  This sample will enable unprecedented tests of the cold dark matter model, e.g., by measuring the redshift evolution of the dark matter concentration and density profile slope.  Furthermore, based on DESI spectra, an optimal set of systems can be selected for a targeted search for multiply-lensed supernovae, which can be used to determine the Hubble constant.  Both objectives are highly complementary to the science goals of the DESI experiment.

May 25, 2021

Valerie Domcke (CERN) “Cosmology with Axion-Like Particles”

Axion-like particles may play a key role in early universe cosmology. They are naturally equipped with the right properties to explain cosmic inflation, can dynamically explain the smallness of the electroweak scale, may be involved in the generation of the matter antimatter asymmetry and are promising dark matter candidates. In this talk I discuss a generic but previously overlooked particle particle production mechanism, resulting in the dual production of gauge fields and fermions induced by axion-like particles. I will discuss how this crucially impacts all of the cosmological scenarios mentioned above and may be probed with upcoming gravitational wave detectors.

May 27, 2021

Mike Williams (MIT)   Searching for physics beyond the Standard Model at the LHCb experiment


The LHCb experiment at the Large Hadron Collider (LHC) at CERN has been the world’s premier laboratory for studying processes in which the quark types (or flavors) change since 2011. Such processes are highly sensitive to quantum-mechanical contributions from as-yet-unknown particles, e.g. supersymmetric particles, even those that are too massive to produce at the LHC. I will discuss the status of these searches, including some intriguing anomalies. I will also present searches for the proposed dark matter analogs of the photon and the Higgs boson. Planned future upgrades and the resulting physics prospects will also be discussed, including our plans to process the full 5 terabytes per second of LHCb data in real time in the next LHC run.

Jun 03, 2021

Julien Guy (LBNL)

Jun 17, 2021

Gaia Lanfranchi (INFN)

Jun 24, 2021

J. Pedro Ochoa-Ricoux (UCI)”TBA”

Jun 24, 2021

Pedro Ochoa-Ricoux (UCI) “JUNO: a 20 kton Multi-Purpose Observatory for Neutrino Physics and Astrophysics”

The Jiangmen Underground Neutrino Observatory (JUNO) is a multi-purpose neutrino detector under construction in China. With a 20 kton neutrino target, and an energy resolution of 3% at 1 MeV, it will be the largest and most precise liquid scintillator detector ever constructed. By studying the disappearance of antineutrinos emitted from 8 nuclear reactors at a strategic baseline of about 53~km, JUNO will determine the neutrino mass ordering to ~3? significance within 6 years of running and will measure 3 neutrino oscillation parameters to sub-percent precision. JUNO will also study neutrinos from a variety of natural sources, such as the Earth, the Sun, and supernova explosions, and will deploy a satellite detector called JUNO-TAO that will measure the energy spectrum of reactor antineutrinos with unprecedented precision. The experiment is currently under construction, and completion is expected by 2022. JUNO’s physics prospects will be discussed in this talk alongside its ambitious design and current status.

Jul 22, 2021

Anna Porredon (Ohio State University) “Dark Energy Survey Year 3 Results from Galaxy Clustering and Weak Lensing”


The cosmological information extracted from photometric surveys is more robust when multiple probes of the large-scale structure of the universe are used. Two of the most sensitive probes are galaxy clustering and weak lensing. I will present cosmological results from the Dark Energy Survey first three years of observations combining those two probes, using an optimized lens sample of 11 million galaxies for the clustering measurements. The shear catalog used for weak lensing contains more than 100 million galaxies, constituting the largest dataset to date of this kind. I will show how we optimized the selection of this lens sample in terms of the forecasted cosmological constraints. Last, I will explain how we validated the analysis to deliver robust cosmological constraints.

Sep 23, 2021

Anya Butter (Heidelberg University) “Big Data Techniques for Precision Simulations and Optimal Observables”

Over the next years, measurements at the LHC and the HL-LHC will provide us with a wealth of data. The best hope of answering fundamental questions like the nature of dark matter, is to adopt big data techniques in simulations and analyses to extract all relevant information.
On the theory side, LHC physics crucially relies on our ability to simulate events efficiently from first principles. In the coming LHC runs, these simulations will face unprecedented precision requirements to match the experimental accuracy. Innovative ML techniques like generative models can help us overcome limitations from the high dimensionality of the parameter space. Such networks can be employed within established simulation tools or as part of a new framework.
At the analysis level, machine learning methods have already shown impressive performance boosts for instance in top tagging and jet calibration. While neural networks offer an attractive way to numerically encode functions, actual formulas remain the language of theoretical particle physics. Symbolic regression trained on matrix-element information provides optimal LHC observables in an easily interpretable form.

Sep 30, 2021

Nedaa Alexandra Asbah (Harvard) “Evidence of the Four-Top-Quark Production at the LHC”


A summary of the latest results on the evidence of the four-top-quark production using proton-proton collision data at a centre of-mass energy of 13 TeV collected by the ATLAS detector at the Large Hadron Collider with an integrated luminosity of 139 fb?1. Events are selected if they contain a same-sign lepton (electron or a muon) pair or at least three leptons (2lSS/3l) or a single lepton or an opposite-sign lepton pair (1l/2lOS). A multivariate technique is used to discriminate between signal and background events in the signal rich regions.

The combined four top-quark production cross section is measured to be 24 +7/?6 fb, with a corresponding observed (expected) signal significance of 4.7 (2.6) standard deviations over the background-only
predictions. It is consistent within 2.0 standard deviations with the Standard Model expectation of 12.0 ± 2.4 fb.
Talk Recording Link:

Nedaa Alexandra Asbah (Harvard) Talk

Oct 07, 2021

Kendall Mahn (Michigan State University) “Results from T2K  and the current landscape of neutrino oscillation”


Neutrinos are a tiny subatomic particle with surprising properties under active study. In particular, neutrinos oscillate, that is, they convert from one type of neutrino to another, is a surprising phenomenon under active study. The origin of neutrino mass is important for astrophysics, cosmology and particle physics, and many open questions surrounding neutrino oscillation exist. The Tokai-to-Kamioka (T2K) neutrino oscillation experiment sends a beam of muon flavor neutrinos or antineutrinos 295km across Japan. This seminar will discuss the state of the field of neutrino oscillation physics, including recent results from T2K, and T2Ks exciting future program.

Oct 14, 2021

Christian Bauer (LBNL) “Quantum computing for High Energy Physics”


I will review the Quantum Computing efforts in the Physics division, with the goal of allowing to calculate important properties of the Standard Model non-perturbatively and ultimately to simulate scattering at colliders from first principles. I will present several results, both on physics simulations and on noise mitigation, which is crucial to obtain results on near-term devices.

Oct 21, 2021

Derun Li (LBNL) “Overview of the Muon Collider challenges and R&D Progress under the US Muon Accelerator Program (MAP)”

There is an increasingly growing interest in Muon Collider in High Energy Physics community and Snowmass 2021.  Considerable progresses have been made under the US Muon Accelerator Program (MAP) to target technical challenges associated with Muon Collider.  The US MAP was recommended for termination by P5 in 2014, and all relavent R&D efforts and international MICE commitment officially ended in 2018. I will give an overview of the US MAP efforts on Muon Collider, technical challenges and progresses, in particular Berkeley Labs role and major contributions for Muon Collider R&D and international MICE. At the end, I would like to give an outlook of Muon Collider R&D and lessons learned from the US MAP and international MICE.

Oct 28, 2021

Laura Jeanty (Oregon) “Perspectives from Run 2: Status and Outlook for Supersymmetry Searches at the LHC”

The second run of the LHC, from 2015-2018, produced an unprecedented trove of data in which the ATLAS and CMS collaborations have been searching for evidence of new particles and new phenomena. Supersymmetry remains one of the most promising theories for new physics accessible at the LHC which could address outstanding questions in particle physics, from why the Higgs Boson has the mass that it does to the particle nature of dark matter. As beam returns now to the LHC for the first time since 2018 and the start of Run 3 is around the corner, this talk will take a moment to summarize the status of searches for supersymmetry by the ATLAS and CMS experiments. The talk will highlight the Run 2 perspective on supersymmetry, with a focus on the experimental constraints, and will discuss some of the well-motivated ways in which it could have evaded detection thus far. The talk will conclude with an outlook for future searches. 

Nov 09, 2021

Caterina Vernieri (Stanford) “A “Cool” Route to Unveil the Higgs Bosons Secrets”

The Higgs boson was discovered in 2012 by the ATLAS and CMS experiments at the worlds most powerful particle collider, the Large Hadron Collider (LHC) in Geneva, Switzerland. This particle plays a unique role in fundamental physics. It gives all of the known elementary particles, including itself, their masses. While we now have a strong evidence that the Higgs field is indeed the unique source of mass for the known elementary particles, the next step is to search for new interactions that could also explain why the Higgs field has the properties required by the Standard Model of particle physics.  We have no clear roadmap to this new theory but the Higgs boson plays a crucial role in this quest. This talk highlights the current experimental results of Higgs boson couplings to other particles and its self-coupling at the LHC and perspectives at future colliders. The goal of a next-generation collider is to carry out precision measurements to per-cent level of the Higgs boson properties that are not accessible at the LHC. The exploitation of the complementarity between LHC and future colliders will be the key to understanding fundamentally the Higgs boson. The Cool Copper Collider (C^3) is a new concept for linear e+e- collider that could provide a rapid route to precision Higgs physics with a compact footprint.

Nov 16, 2021

Taylor Hoyt (University of Chicago) “Using Astrophysical Distance Indicators to Test Standard Cosmology”

Measurements of the universe’s present-day expansion rate, or the Hubble constant (H0), that use a Cepheid variable star calibration of Type Ia supernovae (SNe Ia) are in >4? disagreement with values predicted by the standard, Lambda cold dark matter (LCDM) model of the universe. In this talk, I will review the evidence for this Hubble Tension and discuss in particular my work on an alternative calibration of the SNe Ia using the Tip of the Red Giant Branch (TRGB), a standard candle that can return distances precise to 2% when observed in ancient populations of stars. Anchored by the TRGB, we derived in the Carnegie Chicago Hubble Program a SN value of H0 that is significantly less in tension with base LCDM (<2?) than the Cepheid-calibrated SN H0, which raises the question of underestimated uncertainties and softens evidence for new physics. I will identify likely causes of this Cepheid-TRGB divergence, present paths to a potential resolution, and highlight how the astrophysical distance scale can converge on a self-consistent, 1% determ

Nov 18, 2021

Emily Ann Thompson (DESY) “The Quest For Long-Lived Particles: Searching For Displaced Vertices and Tracking in the Trigger”


The existence of long-lived particles (LLPs) is a common feature in many theories beyond the Standard Model. For example, models with small couplings (i.e. R-parity-violating supersymmetry) and models with compressed mass spectra (i.e. co-annihilating dark matter) predict the presence of LLPs. With lifetimes ranging from picoseconds to nanoseconds, massive LLPs could decay to several electrically charged particles in the inner tracking volume of the ATLAS detector, resulting in the reconstruction of a displaced secondary vertex. Integrating tracking information into the trigger at an early stage is critical to enhancing the sensitivity of future searches for LLPs with displaced track signatures. The ATLAS Fast TracKer (FTK) aimed to achieve this by performing global, hardware-based track finding at a trigger rate of 100 kHz.

In this talk, searches for new long-lived massive particles leaving a displaced vertex signature in the ATLAS inner detector with the full Run-2 dataset are presented. Furthermore, the FTK system is presented and its application to LLP searches is discussed.



Nov 22, 2021

Dominique Trischuk (University of British Columbia) “Displaced Vertex Search for Heavy Neutral Leptons with the ATLAS Detector”


This seminar will present recent results of a search for long-lived heavy neutral leptons (HNLs) in proton-protoncollisions at the Large Hadron Collider (LHC). The Standard Model (SM) of particle physics is an extremely successful theory and its major predictions have been precisely confirmed. However, the existence of neutrinos, with small nonzero masses, provides evidence that the SM is incomplete. Introducing HNLs into the SM is a natural wayto generate the light neutrino masses through a seesaw mechanism. This search uses 139 fb -1 of ATLAS experimental data collected between 2015 and 2018 at a centre-of-mass energy of 13 TeV. A non-standard techniqueis used to search for a displaced vertex from particle trajectories produced in the HNL decay to leptons. The dominant background from uncorrelated leptons crossing in the ATLAS detector is estimated using an objectshuffling method. The reconstructed HNL mass is used to discriminate between signal and background. No excessof events is observed and constraints on the strength of the interactions between HNLs and neutrinos are imposed in various scenarios.

This seminar will conclude with a presentation of methods used to study the detector performance and readout system of the ATLAS Inner Tracker (ITk). The LHC is currently undergoing upgrades that will enable it to produce more than ten times the data that has already been collected. To meet the requirements of this challenging new environment, an all-silicon particle tracking system will be installed in ATLAS.

Nov 23, 2021

Oliver H.E. Philcox (Princeton) ” Large Scale Structure Beyond the 2-Point Function”


Quantum fluctuations in inflation provide the seeds for the large scale distribution of matter today. According to the standard paradigm, these fluctuations induce density perturbations that are Gaussian distributed. In this limit, all the information is contained within the pairwise distribution of galaxies, usually represented by a power spectrum. Today, the distribution of matter is far from Gaussian, with structures forming across a vast range of scales. To date, almost all spectroscopic analyses have used only the two-point function. This begs the question: can we extract more information using higher-point statistics? 

In this seminar, I will present a pedagogical overview of the leading-order non-Gaussian statistics, and demonstrate how they can be used both to sharpen constraints on known physical parameters, and to provide stringent tests of new physics occurring in the early Universe. One of the major barriers to constraining cosmology from the higher-point functions is computational: measuring the statistics with conventional techniques is infeasible for current and future datasets. I will discuss new methods capable of reducing the computational cost by orders of magnitude, and show how this facilitates a number of exciting new tests of the cosmological model. Such techniques are already being applied to data from BOSS; the corresponding pipelines can be simply reapplied to DESI data, and will lead to sharper parameter constraints without additional observing time.

Nov 30, 2021

Robin Hayes (University of British Columbia; Canada) Probing the Standard Model Through Measurements of the Higgs Boson with the ATLAS Detector


As the most recently-discovered particle of the Standard Model (SM), the Higgs boson plays a key role in the quest to deepen our understanding of fundamental physics. Measurements of its production cross-sections probe for disagreement with the SM that might hint at signs of new physics. I will present recent measurements of gluon fusion (ggF) and vector boson fusion (VBF) Higgs production in the H->WW*->evuv decay channel, using data from the ATLAS detector at CERNs Large Hadron Collider (LHC). These measurements are challenging due to the high-background environment, where on average fewer than one in one billion proton-proton collisions produces Higgs bosons. I will discuss novel analysis techniques and improvements that allow the first observation of the H->WW* process in the VBF channel and precise measurements of Higgs boson cross-sections in important kinematic regions. As preparations for the next LHC runs continue, I will lay out further ways in which the current and future LHC datasets can be exploited to creatively test the SM through Higgs physics.

Dec 01, 2021

Boryana Hadzhiyska (Harvard) “Uncovering physics from Stage-IV cosmological experiments with accurate galaxy models”

Over the next few years, cutting-edge cosmological experiments such as DESI, Rubin and CMB-S4 will provide an exquisite probe of the accelerated expansion of the Universe, structure formation, and general relativity, and thus bring us closer to revealing the nature of dark energy, dark matter, inflation and neutrinos. One of the most critical issues with these experiments will be the connection between observed galaxies and the underlying matter field. My research program offers a viable path for constructing accurate models of the galaxy-matter connection and applying them to observational analysis, with the goal of recovering the missing pieces of our cosmological model. In particular, I will share my contributions to the development of state-of-the-art cosmological simulations and analysis tools and propose readily reachable goals for extracting cosmological information from the ongoing DESI and CMB experiments. Future breakthroughs will likely be the product of collaborative efforts across all of cosmology, galaxy formation and particle physics. My broad-scaled research proposal will bring together diverse ideas and aid LBNL science goals at the crossroads of cosmological discovery.

Dec 02, 2021

Brendon Aurele Bullard (Harvard) Toward Precision Measurements of the Higgs Yukawa Couplings 


With the discovery of the Higgs boson in 2012, high energy physics has entered an era in which all fundamental particles predicted by the Standard Model have been observed. With no conclusive observations of physics beyond the Standard Model, precision tests of the properties of the Higgs boson are key to find indications of new physics. I will discuss the program of precision measurements of the Higgs Yukawa coupling strengths with the ATLAS experiment, focusing on those of the muon and top quark. I will give an overview of the search for Higgs decays in the dimuon channel with an emphasis on the novel use of quark/gluon tagging in an ATLAS Higgs measurement. Secondly, I will present the status and outlook for the joint measurement of ttW and ttH production in multi-lepton final states with an emphasis on ttW modeling, fake lepton estimation, and profile-likelihood unfolding. Finally, I will discuss the importance of the High Luminosity LHC for these physics goals in terms of sensitivity projections and the extension of tracking instrumentation provided by the ATLAS ITk upgrade.

Dec 07, 2021

Miao HU (MIT) Vector Boson Scattering in the Post-Higgs-Boson-Discovery Era


The observation of a Higgs boson with a mass of about 125 GeV confirmed the nature of the electroweak symmetry breaking (EWSB) predicted by the standard model of particle physics, establishing that the W and Z gauge bosons acquire their mass via the Higgs mechanism. However, the discovered Higgs boson might not be the lone player responsible for EWSB. Further insights into the Higgs and the gauge bosons mutual- and self-couplings can be obtained from measurements of vector boson scattering (VBS) processes.

In this talk, I will present the study of same-sign WW, WZ, and ZZ boson pair productions in association with two jets with data collected by the CMS detector. The effort led to the most precise measurement of the EW same-sign WW cross section to date and the first experimental observation of the EW WZ production. It also formed the basis for the first measurements of the polarized VBS. Interpretations beyond the standard model, including the constraints on the structure of quartic vector boson interactions in the framework of effective field theory, will also be discussed.

Dec 08, 2021

Maria Mironova (Oxford) First Direct Constraint on the Higgs-Charm Coupling and its Expected Evolution with the ATLAS Detector Upgrade


The coupling of the Higgsboson to charm quarks has eluded experimental observation since the Higgs boson discovery in 2012. At present, this is the largest contribution to possibleHiggs boson decays that is not experimentally verified. However, this measurement is crucial to shed light on the fundamental coupling of the Higgs boson to second-generation quarks. This seminar highlights the recent search for Higgs boson decays into a pair of charm quarks, produced in association with a vector boson, using the data collected by the ATLAS detector between 2015 and 2018.This measurement sets the first direct limit on the Higgs boson coupling to charm quarks

With the upgrade to High-Luminosity LHC (HL-LHC), a significant improvement to this measurement is expected due to the increased size of the dataset as well as the upgrade of the ATLAS Inner Tracker (ITk). A new pixel detector system will improve resolution, increasing the identification efficiency of charm quarks. However, the detector will have to cope with higher data rates and withstand higher levels of radiation. The ITk pixel upgrade, particularly the characterisation of the pixel readout chips, and the expected precision of the measurement of the Higgs boson coupling to charm quarks at the HL-LHC are discussed.

Dec 09, 2021

Vetri Velan (UC Berkeley) The Present and Future of Dark Matter Direct Detection


Dark matter is one of the primary unsolved problems in modern particle physics. Since the late 1980s, physicists have been trying to directly detect dark matter particles passing through the Earth, typically by searching for nuclear recoils. This search has been unsuccessful so far, but I will discuss recent advancements and upcoming technologies that offer a promising path forward. First, I will present xenon time projection chambers, including the LUX and LUX-ZEPLIN experiments, as the best strategy for detecting Weakly Interacting Massive Particles (WIMPs). I will explain how understanding energy deposition in liquid xenon allows us to test the remaining WIMP parameter space, and I will discuss recent data-driven and simulation-driven advancements in this field. Second, I will discuss calorimetry as a tool for probing dark matter models below the WIMP scale, with masses on the order of 1-1000 MeV/c2. I will describe the TESSERACT project, using transition-edge sensors to achieve unprecedented sensitivity to a variety of dark matter interactions.

Dec 14, 2021

Field Rose Rogers (MIT) “The GAPS Antarctic Balloon Experiment: Low-energy Antinuclei for Dark Matter Detection”


Despite overwhelming evidence of abundant dark matter in the Universe, the nature of this material remains a mystery. The General Antiparticle Spectrometer (GAPS) is an upcoming NASA Antarctic balloon mission to search for signatures of dark matter annihilation or decay in the fluxes of low-energy (<0.25 GeV/n) cosmic antinuclei. GAPS will produce a precision cosmic antiproton spectrum extending to an unexplored low-energy regime, with sensitivity to light dark matter models, primordial black holes, and cosmic-ray propagation. GAPS will also either provide the first unambiguous detection of a cosmic-ray antideuteron or exclude the viable dark matter models that predict a low-energy antideuteron flux orders of magnitude above the astrophysical background. To identify these rare low-energy antinuclei while rejecting the abundant positive- nucleus backgrounds, GAPS pioneers a novel exotic atom-based particle identification technique, which relies on a system of >10 m2 of large-area high-temperature lithium-drifted silicon (Si(Li)) detectors. I will discuss the GAPS science program, with a special emphasis on the exotic atom method of particle identification and the Si(Li) detectors that are central to its success.

Dec 16, 2021

Afroditi Papadopolou (Massachusetts Institute of Technology) Lepton-Nucleus Scattering Constraints For Neutrino Interactions And Oscillations


Neutrinos exist in one of three types or flavors (?e ,?µ or ?? ), which oscillate from one to another when propagating through space. This phenomenon is one of the few that cannot be described using the Standard Model of particle physics and its study can thus provide new insight into the nature of our universe. As neutrinos interact only via the weak force, they are experimentally detected only following their interactions with atomic nuclei. Our understanding of such interactions is crucial for measuring neutrino oscillations. In this talk I will review key open questions in the study of neutrino oscillations that drive the need for improved understanding of neutrino-nucleus interactions. I will then present our studies of such interactions using both neutrino and electron beams with the MicroBooNE and CLAS detectors and their impact on next-generation high-precision neutrino oscillation measurements with the DUNE and Hyper-Kamiokande experiments.