Michael David Krohn (University of Minnesota)
- Heavy neutrinos at the LHC Abstract: There is a large, ongoing search program for heavy neutrinos at the LHC due to the variety of beyond the Standard Model (SM) theories that predict the existence of these particles. Heavy neutrinos provide a mass generation mechanism for SM neutrinos and an explanation for their small values compared to other fermions. A popular type of theory that predicts heavy neutrinos are left-right symmetric extensions of the SM which provide an explanation for parity violation of weak charged current. In this seminar, I will present a search for a heavy neutrino based on left-right symmetric models using Run2 collision data collected by the CMS detector. This recent search was able to extend the reach of previous searches to small heavy neutrino masses by utilizing boosted objects. I’ll also explain plans to improve on this search in the Run3 data that is currently being collected at the LHC.
NOTE: Michael would also share/chat about his expertise in HGCAL activities that are ramping up at Fermilab in an effort to get people to come and help out. Michael has travel funds that can at least partially support any invited talk.
Brent R. Yates ( Ohio State University)
What is the universe hiding? - With all our achievements in modern particle physics, we still cannot account for 95% of the energy content of the universe. No direct evidence exists for a particle description of dark matter, and the LHC has provided no clear evidence of physics beyond the standard model (SM). It has been postulated that any new particles are simply too heavy to be produced directly in the LHC. The framework of effective field theory (EFT) may give us a way to still probe for new physics beyond the current energy scale. The standard model effective field theory (SMEFT) allows us to cast potential new physics in terms of the SM fields, and make predictions which can be directly tested at the LHC. Using data collected from the CMS detector during Run 2 (2016-2018), we perform a search for deviations in the number of events observed relative to the SM. Simulations are generated using an EFT model and may be parameterized in terms of coefficients, where non-zero values represent deviations from the SM. Statistical inference is performed to extract the 95% confidence intervals for these coefficients. No significant deviation from the SM is currently observed.
Shengquan Tuo (Venderbilt University)
Particle Azimuthal Correlations in Quark-Gluon Plasma Abstract
Flow, Nonflow, and Flow Fluctuations at CMS Abstract
Yuta Takahashi (University of Florida)
Tackling flavor puzzles using tau-leptons at the CMS experiment - One of the key conundrums in particle physics is the three-generation structure of the fermions and its vastly different mass spectra. A currently unknown physics interaction at the beginning of the Universe, i.e., at a high energy scale, which acted differently depending on the fermion flavor, could have shaped the 'flavor structure' we see today. I will review my ongoing research projects at CMS to find such a new interaction by focusing on its couplings to tau leptons. The project includes:
Valentina Dutta (Carnegie Mellon University)
Seeking the invisible: in search of new physics to illuminate dark matter - Searches for invisible particles play an important role in the quest to understand the nature of dark matter. At the Large Hadron Collider (LHC), searches for Supersymmetry, a hypothesized symmetry of nature relating fermions and bosons, explore the production of weakly interacting massive particles (WIMPs) that leave no visible signature in the detectors and could be the constituents of dark matter. I will review results from searches for Supersymmetry, which could also help to address the hierarchy problem affecting the Standard Model of particle physics, with the Compact Muon Solenoid experiment at the LHC. Moving beyond the well-explored WIMP dark matter paradigm, I will discuss a search for “light dark matter” candidates with masses between the electron and proton mass scales, framed by the possibility that dark matter is part of a “hidden sector” and does not interact directly with Standard Model matter. Despite being the mass range in which most stable forms of ordinary matter are found, this range has been much less explored in the past. I will present an exciting experimental prospect that promises unprecedented sensitivity in the search for dark matter in this regime: the Light Dark Matter eXperiment (LDMX).
Raghav K. Elayavalli (Vanderbilt)
Back to fundamental QCD - how do quarks and gluons evolve in space and time? - Collider experiments have proven themselves immensely useful in studying the behavior of fundamental particles such as quarks and gluons. The last few years in particular have seen a push towards an exploration of QCD that has hitherto been inaccessible via innovative techniques to experimentally access the multi-scale parton evolution and eventually even hadronization. In this talk, I start with a pedagogical overview of jets and their structure and highlight recent measurements from experiments at both RHIC and LHC. In the context of heavy ion collisions, jets have been advertised for the past two decades as a useful tool for quark-gluon plasma (QGP) tomography. This quest has had its fair share of roadblocks but I provide a roadmap to the next-generation of measurements that have potential to enable an extraction of the QGP's microscopic transport properties and mapping its space-time evolution. Finally, I cover the impact of the upcoming Electron Ion Collider where these novel techniques and experimental precision lead to imaging both the perturbative and non-perturbative QCD regimes, allowing us unprecedented access into color confinement and hadronization.
Andrew Brinkerhoff
Double Higgs and ttX: Portals to New Physics - A decade after discovering the Higgs boson, LHC scientists are still looking for some sign of physics beyond the Standard Model (BSM) in high-energy proton collisions. While most new physics searches focus on direct evidence for BSM particle production, Effective Field Theory (EFT) enables us to explore BSM effects even above the LHC collision energy of 13.6 TeV. The EFT approach uses measurements of SM particles to detect anomalies in their interactions, which could indicate BSM effects at some higher mass scale. I will present two CMS analyses which incorporate EFT interpretations: a search for double Higgs (HH) production, focusing on Higgs decays which produce multiple charged leptons; and a measurement of top pair production in association with a Z or Higgs boson (ttX) in events with a high-momentum "boosted" Z or H decaying to a bottom quark pair. These extremely rare interactions offer a unique opportunity to probe new physics related to the Higgs boson and top quark.
Doug Berry
Track to the future - The LHC is not only the highest energy, but also the highest intensity proton-proton collider ever constructed. In 2016, the LHC exceeded its initial designed luminosity of 10^34 cm-2s-1, and since then, it has further increased to a record setting 2.06E34 cm-2s-1. The increase in luminosity has created a higher occupancy, radiation, and pileup environment, which requires an increasingly robust detector. The first of such adaptations was the CMS phase-I pixel upgrade. This pixel upgrade improved the pixel detector's bandwidth, tracking efficiency, radiation tolerance, and material budget in order to ensure physics performance up to the HL-LHC era. The next proposed tracking upgrade is a complete replacement of the inner and outer tracker. The HL-LHC Outer Tracker Upgrade is a monumental change that increases the detector's granularity, hit coverage, readout speed, triggering capabilities, radiation hardness, and cooling capabilities. This seminar will cover the construction, installation, and performance of the CMS phase-I pixel upgrade and the design, progress, and expected physics performance of the HL-LHC outer tracker upgrade.
Abdollah Mohammadi
Higgs boson as a portal to new physics - The discovery of the Standard Model Higgs boson represented a thrilling triumph for the particle physics community and an outstanding achievement for the LHC. Even though unraveling of the Higgs boson puzzle completed the final chapter of the Standard Model's book, a number of major questions in particle physics, such as hierarchy problem, matter-antimatter asymmetry, and the nature of dark matter remain unresolved. In my presentation, I will discuss how the SM Higgs boson can be exploited as a tool for new discoveries. In particular, I will review a set of searches where the Higgs boson decays in an exotic, non-SM, fashion. I will conclude my presentation with an overview of the future of the LHC, and how the upgrade of the detectors can open up new search directions.
Nadja Strobbe
Under the radar: searching for stealthy new particles with jets - Many searches for supersymmetry (SUSY) have been performed with the LHC data, and so far, none have found any signs of physics beyond the standard model. A common strategy employed by these searches is the requirement that there be a substantial amount of missing transverse momentum (MET) originating from undetected SUSY particles. But what if SUSY takes a form that instead produces low-MET final states? These types of models would evade detection in standard searches. In this seminar I will discuss the results of a recent CMS search for top squarks in final states featuring top quarks and large jet multiplicity (instead of high MET), which can occur from a variety of SUSY models, including stealth SUSY and R-parity violating SUSY. This search relies on machine learning, in particular a technique called gradient reversal, for distinguishing signal from background and for enabling a data-driven background estimation technique. Top squark masses up to 900 GeV (depending on the details of the model) can be excluded at 95% confidence level.
Javier Duarte
Real-time AI in particle physics - Experimental high energy physics is entering an era of unprecedented data rates. The vast majority of the raw data in our experiments are immediately discarded by our real-time trigger systems because of storage and computational limitations. While most of these data are background, we may inadvertently be throwing away precious signals of new physics. One way to expand our discovery potential is by enhancing our real-time on-detector and trigger-level processing capabilities using machine learning (ML). I will discuss applications and opportunities for ML in real-time systems in particle physics, focusing on how to embed ML algorithms in systems with FPGAs and ASICs for a variety of use-cases. I will review essential concepts for designing and optimizing efficient algorithms in hardware and emerging tool flows to accelerate algorithm development. I will then explore a few examples spanning different applications, including more sophisticated trigger algorithms, front-end data compression in radiation-hard environments, and control of particle accelerators.
Kevin Pedro
Coprocessors as a service to accelerate machine learning inference for particle physics - Heterogeneous computing paradigms will be needed to satisfy the increasing demands for computing resources in high energy physics. New coprocessors with extreme parallelization are naturally suited to accelerate machine learning inference; at the same time, there are growing applications of machine learning for simulation, reconstruction, and analysis. In particular, deploying coprocessors as a service requires minimal modification to the current computing model, while increasing efficiency and flexibility. Inference as a service offers easy portability of algorithms to both local and cloud resources. The latest results with GPUs and FPGAs show more than an order of magnitude reduction in inference latency and high throughput. This demonstrated performance is sufficient to address the computing challenges faced by both energy frontier and intensity frontier experiments, including the HL-LHC detectors and DUNE.
Is the dark force strong? New directions for LHC dark matter searches The nature of dark matter remains one of the outstanding questions in particle physics. To date, collider searches have produced no evidence of an excess of events with large missing transverse momentum, which would be an indicator of the simplest models of weakly interacting massive particles. Instead, we pursue a new strategy based on models of composite dark matter, specifically "dark hadrons" that arise from a dark sector with a new strong force called "dark QCD". These models are motivated by both theoretical and experimental considerations. We present the latest results from Run 2 CMS searches for the novel phenomenological signatures of dark QCD, including semi-visible jets and emerging jets. The prospects for the future and evolution of the dark QCD program will also be discussed.
Andrew Brinkerhoff, Baylor University:
Higgs couplings: great and small - Just 8 years after the Higgs boson was discovered, the CMS and ATLAS experiments at CERN have precisely measured most of its properties. The observed Higgs lifetime, spin, and parity, and its interactions with weak bosons, bottom quarks, and tau leptons all agree with the Standard Model predictions, ruling out many new physics models. I will present two of the most recent Higgs measurements from CMS, including the first direct detection of the Higgs' coupling to the top quark, and the first evidence for ultra-rare Higgs boson decays into muons.
Ted Kolberg, Florida State:
A Particle Flow Calorimeter for the CMS High Luminosity Upgrade: - The upgraded CMS experiment at the High Luminosity LHC will integrate 10 times the amount of luminosity of the original experiment. With this large increase in luminosity we will significantly expand our understanding of Higgs physics, and enable new searches for physics beyond the Standard Model. Along with these opportunities come significant challenges in coping with the high event rate, large amounts of pile up, and harsh radiation environment. The upgraded CMS endcap calorimeter will adopt a highly segmented design, optimized for use in particle flow reconstruction, with built in capabilities for precision timing. An overview of the project will be presented.
Phil Harris, MIT:
Discovering the Higgs all over again. Now with Machine Learning. - Standard model production of the Z (or W) boson decaying to light quarks had not been observed in a hadron collider; it was thought to be impossible. We present a new technique to observe these productions and we observe a clear W and Z peak and with the addition of Machine Learning, we apply this approach to resonances decaying to b-quarks including, for the first time, Higgs bosons decaying to b-quarks produced through gluon fusion. From these results, we observe serious limitations in our computing and data flow model and we present a new approach to overcome these limitations through the use of a heterogenous computing model relying on FPGAs and CPUs. Finally, we look at the broader scope of accelerated computing in LHC physics and discuss how ML can lead the way to fundamental, yet to be performed, measurements at the LHC.
John Alison, Carnegie Mellon:
Di-Higgs Production at the LHC: Current Status and Future Prospects - The Standard Model (SM) of particle physics is a spectacularly successful theory that is known to be fundamentally incomplete. The discovery of the Higgs boson at the Large Hadron Collider is, on one hand, the final missing piece of the SM and, on the other, a window into what lies beyond. Processes involving pairs of Higgs bosons are a sensitive probe of new physics and will ultimately allow the shape of the (in)famous Higgs potential to be directly explored experimentally. I will discuss the motivations and experimental challenges of searching for Di-Higgs production at the LHC. Emphasis will be placed on the dominant hh->4b channel.
Zeynep Demiragli, Boston:
Dark Matter Search - 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.
Rachel Yohay, FSU:
talk 1: Searches for Exotic Higgs Decays at CMS - Although the 125 GeV Higgs scalar displays spin, parity, and fermionic and bosonic couplings consistent with those predicted by the Standard Model (SM), constraints on its branching ratio to invisible or non-SM final states are only at the 20-30% level. Direct searches for Higgs decays to invisible or non-SM final states offer further insights into the structure of the Higgs sector, specifically whether it consists of the single doublet of the Standard Model, or multiple doublets as proposed by many theories that extend the Standard Model. In this talk, I will present recent results on searches using data collected by the Compact Muon Solenoid (CMS) detector for Higgs decays to non-SM final states, focusing on decays that proceed via new light Higgs states. Along with general search strategies and interpretations of the current data in terms of two-Higgs-doublet models, dedicated methods for reconstructing low-transverse-momentum and boosted particles characteristic of such decays will be discussed.
talk 2: Operation of the CMS Pixel Detector Since 2017 - The interaction point of the Compact Muon Solenoid (CMS) experiment is surrounded by pixelated silicon sensors that form the heart of the CMS charged particle tracking system. The currently operating pixel detector was installed in February 2017 as part of the CMS Phase 1 upgrade plan, replacing the original nine-year-old detector whose readout electronics were not suited to the expected event rates of Runs 2 and 3 of the Large Hadron Collider. With a pixel size of 100 x 150 microns, the pixel detector is designed to maintain a hit resolution in the transverse(longitudinal) coordinate of ~20(50) microns or better for tracks with transverse momentum above 10 GeV. The high resolution of the pixel detector allows for the efficient reconstruction of, on average, 30 primary pp interaction vertices per event, as well as secondary vertices characteristic of b quark jets. In this talk, I will present the motivation for and design of the new pixel detector, the successes and challenges of its operation so far, and its impacts on CMS particle reconstruction.
Andrew Whitbeck, Texas Tech:
- Observing the invisible: missing energy/momentum signatures at accelerators & their implications for new physics Elucidating the non-gravitational interactions of dark matter motivates searches for new physics with missing energy/momentum signatures at accelerators. At the LHC, WIMPs are actively being searched for in the context of, among other models, Supersymmetric extensions to the SM (SUSY) which predict new sources of events with missing energy and high multiplicities of SM particles. New results from searches at CMS for R-parity conserving SUSY using 13 TeV proton-proton collisions will be discussed along with their implications for the hierarchy problem. While these results are an important piece of the program for testing WIMP dark matter, a growing need to fully explore the thermal dark matter paradigm was recently highlighted by the community-driven Cosmic Visions white paper. Among the most unconstrained regions of thermal dark matter parameter space is that of so-called light dark matter (LDM), 1 MeV < m_{DM} < 1 GeV. A new class of experiments will be described which will provide the necessary sensitivity to test many models of thermal dark matter in this LDM region of parameter space. Experimental challenges of fixed target experiments, such as LDMX and M^3, looking for LDM will be discussed along with prospects for applying CMS detector technology to address these challenges.
David Sperka, Boston:
Two Zs, or not two Zs? Searches for dark forces in CMS - The Z boson has played a fundamental role in the development of the Standard Model. It's presence was first inferred from the observation of "neutral current" interactions at CERN, the first verification of a prediction from the electroweak theory of Glashow, Weinberg, and Salam. At the LHC, the Z boson plays a crucial role as a standard candle in nearly every measurement and search, as well as in the discovery and precision measurements of the Higgs boson. Interestingly, the Z boson may not be the only heavy neutral vector boson. Many theories physics beyond the standard model predict extended gauge sectors, and searches for heavier "Z'" bosons are a cornerstone of the LHC search program. Recently, searches for lighter Z' bosons have seen renewed interest as they may be a mediator to a dark matter sector or provide a solution to experimental anomalies such as possible Lepton Flavor University Violation in b->sll processes or the measured value of the muon's anomalous magnetic moment. I will describe the latest searches for these lighter "dark force" mediators in CMS, including the first ever search for a dimuon resonance performed entirely using trigger level reconstruction. Finally I will comment on the future prospects. The title of the talk comes from a 1984 paper which first described the phenomenon of "kinetic mixing".
Julie Hogan, Bethel:
Searches for vector-like quarks at CMS: - At the Large Hadron Collider at CERN, proton collisions at extremely high energies could allow production of particles that are no longer found in nature. The standard model (SM) of particles and forces is amazingly accurate, but we know this model has significant gaps. This suggest new physics is out there in the form of new particles or interactions. Heavy fermions called "vector-like quarks" (VLQs) are motivated by new physics models that seek to resolve the mass scale discrepancy between the Higgs boson and the Planck mass. VLQs are predicted to decay into less massive particles like top quarks or bosons, which gain large momenta compared to their mass. If these secondary particles decay to quarks they leave fascinating signatures in CMS as large showers of radiation that can be analyzed using jet substructure techniques. I will present recent VLQ searches from CMS and the jet substructure methods that make them possible, exploring how deep neural network identification methods could provide a better handle on these elusive new particles.
Nhan Viet Tran, FNAL:
talk 1: Fast & Furious 10: triggers, ML, and computing at the LHC and beyond - With increasingly complex collision environments at the LHC and concurrently growing data rates, more sophisticated detector and reconstruction methods are required to preserve the LHC program. However, this cannot coincide with an upsurge of computational and processing time. I will discuss plans for the CMS hardware trigger in the HL-LHC era and the role of advanced reconstruction techniques and the potential for machine learning implementations in the trigger FPGA hardware. Finally I will show recent results relating this work to advances in computing which could revolutionize future high level trigger and offline computing architectures at the LHC and other large scale experiments like those in the neutrino program.
talk 2: Boosting light new physics at the LHC and LDMX Searching for new physics in dijets at hadron colliders is a classic well-motivated strategy. However, as the LHC settles into a long period of data-taking at 13 TeV, improvements to the traditional search program are incremental. I will present new techniques to greatly extend the dijet search phase space to regions unexplored since the 1980s. I will also detail how such searches have a connection to dark sector searches at the LHC. Finally, I will talk more generally about extending searches for light thermal dark matter to the MeV-GeV range and new experimental approaches such as the proposed LDMX (Light Dark Matter eXperiment).
Indara Suarez, Boston:
A Stop to Natural SUSY? - Questions surrounding the measured value of the Higgs mass as well as astrophysical evidence for Dark Matter suggest that new particles and/or interactions are awaiting discovery. With the significant increase in collision energy and the large datasets of Run 2, it may be possible that data from the Large Hadron Collider will provide evidence for the existence of partners to the top quark. I will discuss the ongoing searches for Supersymmetric partners of the top quark, called top squarks or "stops", and how their discovery could shed light onto the nature of the lightness of the Higgs mass and Dark Matter. My talk will focus on the prospects for the full Run 2 dataset, the detector upgrades that will lay the foundation for exploiting the HL-LHC data, and possible future directions in our search for physics beyond the Standard Model.
Christopher Rogan, Kansas:
Studying invisible particles at colliders with Recursive Jigsaw Reconstruction - At the Large Hadron Collider (LHC), many new physics signatures feature pair-production of massive particles with subsequent direct or cascading decays to weakly interacting particles, such as SUSY scenarios with conserved R-parity, or Higgs decaying to two leptons and two neutrinos through W bosons, often motivated by models of new physics which attempt to mitigate the hierarchy problem in the Standard Model and explain the identity of Dark Matter. While final states containing multiple invisible particles represent an opportunity for discovery of new physics phenomena, they also present a unique experimental challenge; the kinematic information lost through particles escaping detection makes fully reconstructing these collision events impossible. In order to address this shortcoming special kinematic variables are used to partially reconstruct these events, providing sensitivity to properties of the particles appearing in them, including masses and even their spin correlations. We introduce a systematic prescription, Recursive Jigsaw Reconstruction, for generating a preferred kinematic basis of observables developed to study final states with invisible particles at HEP experiments, specifically catered to each case of interest. Using the examples of single W boson production and slepton pair production at the LHC, the motivation and derivation of these observables are described, along with comparisons to previously existing approaches. Generalizations to more complicated decay topologies are also discussed, including fully leptonic top quark pair production (resonant and non-resonant), its supersymmetric analogue of stop pair-production with subsequent decays to b-quarks, leptons, and neutrinos, and several examples involving both SM and BSM Higgs decays. We will also include a summary of recent LHC results using these methods.
Isobel Ojalvo, Princeton:
Higgs to Tau Tau Observation - Discovered approximately 40 years ago using just a handful of events from the SPEAR experiment, the tau lepton was an unexpected addition to the zoo of fundamental Standard Model particles. Due to its very short lifetime, the tau lepton is normally only possible to detect in its decay to lighter leptons and mesons and in a hadron collider it can be very easily mistaken for a quark or gluon jet! This makes the triggering, reconstruction and identification of the tau lepton very difficult, however, if the decay products of the tau lepton can be well reconstructed then this particle serves as a candle for the study of a 125 GeV Standard Model higgs boson in its decays to fermions. Within the past year, the first observation of the Higgs in its decay to Taus was announced at CMS and at ATLAS. We discuss this exciting result, along with recent advances in tau trigger, reconstruction and identification which made this observation possible as well as prospects for future measurements at the LHC.
Andreas Jung, Purdue:
talk 1: Top quark physics at the precision frontier - The talk will highlight latest results on top quark physics at CMS employing pp collision data at a center-of-mass energy of 13 TeV. With millions of top quarks already collected at the LHC top quark physics enters the precision era. Differential cross section measurements and top quark property measurements are challenging the Standard Model predictions. The presentation focuses on the new measurement of the full spin density matrix sensitive to spin correlations and polarization of top quarks. Unfolded results are employed in an effective field theory approach to search for new physics indicating potential heavier top quark partners. The intimate connection of the top quark to the Higgs Boson is scrutinized by highly precise direct measurements of the top quark mass, with alternative approaches entering the precision realm as well. Deviations between theory and experimental measurements might indicate hints for new physics. The talk briefly summarizes top quark physics results at other colliders and experiments, and concludes with implications for the SM and an outlook towards the ultimate precision frontier at the high-luminosity phase of the LHC.
talk 2: A new CMS forward pixel detector for the high-luminosity phase of the LHC - The high-luminosity phase of the LHC provides unprecedented numbers of proton-proton collisions and in turn enormous amounts of top quarks for extremely precise measurements. The talk will outline the design challenge for the forward silicon pixel detector in order to address the high radiation environment in the inner CMS detector region at the HL-LHC of about 1.2 Grad. The large number of pileup in any proton-proton collision commands a drastically increased number of pixels to maintain a low occupancy and viable track reconstruction. Simultaneously, the acceptance of the pixel detector is increased in the forward and backward region allowing for better physics analysis reach. The talk discusses the current design and the solutions for the significant challenge of removing about 40 kW of heat produced by the Silicon pixel detector under normal operation. The talk concludes with presenting a physics performance study showing the non-SM discovery potential at the HL-LHC.
Ketino Kaadze, Kansas State:
Exploring the Higgs Sector with the Tau Leptons - The observation of the Higgs boson by the ATLAS and CMS experiments at the LHC has opened a new era for particle physics, where characterization of this new object is of crucial importance. Tau leptons are highly important for understanding the true nature of the Higgs boson. The di-tau decay of the Higgs boson is a key channel for direct measurement of Higgs to fermion couplings as well as for significant constraints of Higgs to vector boson couplings. These measurements allow testing CP-violating effects in the Higgs sector. In this talk, I will present recent results on observation of the Higgs boson decaying to a pair of tau leptons and on constraints of the Higgs couplings, as well as discuss future prospects for exploring the Higgs sector with di-tau decay mode.
Michalis Bachtis, UCLA:
talk 1: Searches for heavy new resonances decaying to di-bosons with CMS detector at 13 TeV - A search for heavy resonances decaying to pairs of heavy electroweak bosons will be presented. The search is deploying novel signal extraction techniques and jet substructure to improve sensitivity. Results from recent LHC data at 13 TeV will be presented along with future prospects for Run III.
talk 2: Implementation of a Kalman Filter in FPGAs for the upgrade of the CMS Barrel Muon Trigger in Run III and HL-LHC new algorithm is proposed to measure the momentum of muons in the CMS detector in real time using data from the Drift Tube and Resistive Plate Chambers in the central region of the detector. The algorithm features a Kalman filter implemented with DSP cores in modern FPGAs to provide momentum measurement with and without vertex constraint enabling displaced particle searches and improving efficiency while reducing the trigger rate. Details of the firmware implementation, performance and results from CMS data-taking will be presented
Toyoko Orimoto, Northeastern:
The Higgs as a Probe for New Physics with the CMS Detector - Since its discovery at the CERN Large Hadron Collider (LHC) in 2012, the Higgs boson has served as a valuable tool for probing beyond-the-Standard-Model physics scenarios. In this presentation, searches for rare and exotic decays of the Higgs boson will be described, as well as searches for additional Higgs bosons predicted by extensions of the Standard Model. Recent results from the CMS Collaboration, using 13 TeV proton-proton collisions data from LHC Run 2, will be presented. Prospects at the High-Luminosity LHC will also be briefly highlighted.
Alberto Belloni, UMD:
talk 1: Radiation tolerance of plastic scintillators - The experiments at the LHC are expected to accumulate up to 300 fb-1 of data before the major upgrades, known as the “Phase-II” upgrades, are installed. This talk presents studies on the longevity of the active materials used in the barrel and endcap hadronic calorimeters. I will present results of in-situ measurements of the light output as a function of integrated luminosity and studies of light output as a function of dose using various other sources of irradiation both for the current materials and for potential alternative materials that are less susceptible to radiation damage. I will also present results on radiation damage as a function of dose, dose rate, and environmental conditions, and investigate how material composition affects radiation tolerance.
talk 2: Emerging Jets signatures of a composite Dark Sector in the CMS detector… and other long-lived states - Many extensions of the standard model (including SUSY) predict new particles with long lifetimes, such that the position of their decay is measurably displaced from their production vertex, and particles that give rise to other non-conventional signatures. This talk presents recent results of searches for long-lived particles and other non-conventional signatures obtained using data recorded by the CMS experiment at Run-II of the LHC. I will particularly focus on a model of dark-QCD with a peculiar signature consisting of emerging jets.
talk 3: Putting to test the Standard Model: the Theory of (Almost) Everything The Standard Model of particle physics is the theory that describes how elementary particles interact via the electro-magnetic, weak, and strong forces. It successfully withstood more than 40 years of precision tests, but we do know it is not complete. It does not include gravity, and it does not provide a description of dark energy, nor of dark matter, the existence of which astronomical and cosmological observations unambiguously indicate. I will present complementary methods I utilize to put the Standard Model through its paces, with data collected by the CMS detector at the LHC. I will not forget to discuss how a collaboration of ~4000 members from more than 40 countries operates successfully one of the most complex experimental facilities ever built.
Sal Rappoccio, Buffalo:
talk 1: Searches: The energy frontier is at a crossroads. Aside from a small gain to 14 TeV center-of-mass energy at the LHC, higher energies in a proton-proton collider will not happen for decades. The Higgs boson discovery has elucidated the mechanism of electroweak symmetry, but does not explain how its mass is so much different from naive quantum-mechanical expectations. Dark matter remains an enigma. Neutrino masses are not explained. Simple solutions to these questions are mostly ruled out. The next steps in collider searches will appear only if the particles are very heavy, or hidden in some way. I will summarize the existing searches, what they mean for future directions at the LHC.
talk 2: Jets and Jet Substructure: The identification of highly Lorentz-boosted objects has become a standard tool at the LHC. Within 10 years, it has gone from an expert-only tool with high degrees of uncertainty, to a well-established part of the LHC program, with precise understanding of jet substructure from both a theoretical and experimental standpoint. I discuss the current state of jet substructure, including jet substructure measurements and boosted object tagging techniques, and possibilities for improvement of systematic uncertainties in the future.
talk 3: Jet mass cross section: A major limitation in the understanding of jets and jet substructure is the precise description of the jet shower for QCD-initiated jets. A major difficulty has been separating the hard and soft portions of the jet in a systematic way to isolate the tunable soft physics while leaving the hard physics unchanged. The precise measurement of the differential production cross section with respect to jet mass is presented, with and without a jet grooming algorithm applied, to disentangle these portions of the jet. The results are presented over a wide range of transverse momenta, and provide stringent tests of cutting-edge resummation calculations of the groomed jet mass.
Sevil Salur, Rutgers:
Studying Hot QCD with Jets The phase diagram of QCD matter has been studied with relativistic heavy ion collisions. The Large Hadron Collider (LHC) at CERN has delivered heavy ion collisions (Pb+Pb) along with reference data of pp and p+Pb collisions since 2010. With its unprecedented reach in energy, LHC explores new regions of the phase diagram of Quantum Chromo Dynamics (QCD) that can resolve fundamental questions regarding quark confinement, such as What determines the key features of QCD? and How does the hot QCD respond to jet energy loss?. At Rutgers, we have performed multiple, complementary jet measurements at LHC using the CMS detector to answer these questions. This talk will present an overview of our experimental results that reveal detailed properties of the hot QCD matter.
Francisco Yumiceva, FIT:
talk 1: Light-emitting Top Quarks The LHC near Geneva, Switzerland, has been delivering an unprecedented amount of data, using the most energetic proton beams ever devised. A signature of new physics never before observed could well be hidden in the data that we have recorded using the CMS detector. In this talk, I will describe the most precise measurements of the properties of the top quark, which is the heaviest subatomic particle ever discovered. Top quarks are copiously produced at the LHC thus providing us with an ideal opportunity to use them as a tool to search for new physics. In particular, I will describe our latest result on the measurement of the rate of photons emitted from top quarks. We are living in exciting times where new ideas about the universe can be tested in ways never before possible.
talk 2: Top quarks and gauge bosons Abstract available on request
talk 3: Recent CMS results on top quark physics Abstract available on request
John Paul Chou, Rutgers:
talk 1: New physics searches with multijets at the LHC: The great puzzle of the LHC is the paucity of evidence for new physics, despite over three years of proton-proton collisions at 13 TeV. A simple explanation for this fact could be that new physics processes decay predominantly into light (non-top) quarks. Without extra leptons, photons, or missing momentum, Standard Model multijet backgrounds dominate. This is a daunting proposition because theoretical considerations prefer new particles that could easily be as light as 100 GeV. I will begin by considering previous searches for new physics in multijet final states, discussing the pros and cons of the methods used. I will then examine a new technique to search for light pair-produced particles that each decay into four or more light quarks, a topology that arises in natural R-parity-violating supersymmetry. I conclude with a discussion of the potential of this technique for other searches in the context of natural supersymmetry.
talk 2: the MATHUSLA detector proposal: There is substantial theoretical motivation for the production of long-lived particles at the LHC. In this seminar, I will introduce MATHUSLA, a proposed surface level detector above an LHC collision point, which aims to discover ultra-long-lived particles with lifetimes as long as O(1) s, and which would boost the sensitivity of the HL-LHC by orders of magnitude. I begin with a discussion of the theoretical motivations (from naturalness, to baryogenesis, to dark matter), before describing the theory-level detector design. Recent updates on background estimates and technical design for the proposed detector will be presented as well.
Wei Li, Rice:
talk 1: Nearly "Perfect" Quark-Gluon Droplet at the Smallest Scales In high energy collisions of large, heavy nuclei (e.g., Au or Pb), a new state of matter consisting of liberated quarks and gluons is formed at a temperature of a few trillion Kelvins. This "Quark-Gluon Plasma" (QGP), discovered at the Relativistic Heavy Ion Collider (BNL) and the Large Hadron Collider (CERN, Switzerland), is found to exhibit amazing collective behavior as a nearly "perfect" fluid, which flows with close-to-zero viscous dissipation. It was thought that elementary collision systems like proton-proton (pp) or proton-nucleus (pA) are too small and dilute to form a QGP fluid so they were often treated as a reference in understanding the emergence of perfect fluidity in large heavy ion systems. Surprisingly, in recent years, evidence for collective effects and QGP formation has also been revealed in those smallest collisions, when looking at a fraction of rare events releasing largest number of particles. In this talk, I will describe key findings related to the possible formation of the tiniest QGP fluid in pp and pA systems, and discuss their implications to the standard paradigm of heavy ion physics, as well as new opportunities opened up in studying emergent Quantum Chromodynamics phenomena under extreme conditions.
talk 2: Searches for the Chiral Magnetic Effect in nuclear collisions In relativistic nucleus-nucleus collisions, local chirality imbalance of left- and right-handed quarks may be generated by topological transitions of gluon gauge fields, leading to local parity violation of the strong interaction. In presence of an extremely strong magnetic field (~10^{14} Tesla) generated by a non-central collision, an exotic phenomenon called the chiral magnetic effect (CME) has been predicted to occur, resulting in an electric charge current and charge separation in the final state with respect to the reaction plane. In this talk, I will review the approach and latest status of experimental searches for the extreme electromagnetic fields and chiral magnetic effects in nuclear collisions at RHIC and the LHC, and also discuss emerging opportunities with programs planned in the near future.
Conor Henderson, Alabama:
Searches for Extra Dimensions with CMS Discovery of extra dimensions of space would revolutionize our view of the universe. They may also provide a solution to the hierarchy problem of the Standard Model, through modifications of the strength of the gravitational force. This talk explores the theoretical motivations to search for evidence of extra dimensions in proton-proton collisions at the Large Hadron Collider, and presents recent results of such searches by the CMS experiment.
Kristian Hahn, Northwestern:
talk 1: Searches Searches for dark matter (DM) have become a major focus of the LHC physics programmes. Results from Run-2 of the LHC showcase the ability of collider searches to compliment the sensitivity of direct and indirect detection experiments. In this talk I review the strategy and status of DM searches with the Compact Muon Solenoid (CMS) experiment, and show how recent CMS results strongly constrain models of WIMP DM. I will explore the unique sensitivity of several DM search channels, highlighting LHC constraints on low mass DM and spin-independent DM couplings. The talk will also consider the evolution of DM searches toward Run-3 of the LHC, concluding with a discussion of new ideas for extending the reach of future collider-based DM searches.
talk 2: HL-LHC The High Luminosity LHC (HL-LHC) will produce roughly 200 overlapping proton-proton collisions per bunch crossing on average. To mitigate the impact of these extreme conditions, the HL-LHC upgrade of the Compact Muon Solenoid (CMS) experiment will introduce tracking information in its hardware (L1) trigger. A new Track Finding system will reconstruct the trajectories of charged particles from each LHC beam crossing and transmit these tracks to the downstream trigger system. The technical requirements for L1 Track Finding are extraordinary; the system must cope with the enormous data rates generated from the Tracker detector while simultaneously obeying a stringent 4 microsecond latency limit for track reconstruction. The CMS experiment will confront these challenges using an FPGA-based architecture that implements spatial and time-multiplexed data processing. In this talk I will review on-going R&D for the CMS Track Finder, which includes the evaluation of multi-gigabit links and system-on-chip technologies, as well as the investigation of algorithmic optimizations that capitalize on the design of modern FPGAs.
Yen-Jie Lee, MIT:
talk 1: Probing the Quark-Gluon Plasma using Heavy Quarks with the CMS detector Heavy quarks are powerful tools for the study the properties of the hot and dense QCD medium created in heavy-ion collisions. The modification of the heavy flavor meson spectra in heavy ion collisions is expected to be different from light flavors due to the heavier mass of the charm and beauty quarks. The nuclear modification factors (RAA) of heavy-flavor particles provides insights into the flavor dependence of in-medium parton energy loss, and azimuthal anisotropy coefficient (vn) of heavy-flavor particles provides information about the degree of the thermalization of the bulk medium. Moreover, the measurement of the production of strange heavy-flavor mesons could give insights on harmonization mechanism of the Quark-Gluon Plasma. With the experimental data, the transport and thermodynamical properties of the medium could be extracted using phenomenological models. Over the past few years, using the large statistics proton-proton and PbPb samples collected at 5.02 TeV in LHC Run II, high precision measurements of heavy-flavor mesons have been performed with the CMS detector. Recent results and their implications will be summarized in this talk.
talk 2: Study of long-range angular correlations of charged particles in high multiplicity e+e- collisions with archived ALEPH data First results on two-particle angular correlations for charged particles emitted in e+e− collisions using 730 pb−1 of data collected between 91 and 209 GeV with the ALEPH detector at LEP are presented. With the archived data, the correlation functions are studied over a broad range of pseudorapidity η (rapidity y) and azimuthal angle ϕ with respect to the electron-positron beam axis and the event thrust axis. Short-range correlations in Δη (Δy), which are studied with e+e− annihilations which reveal jet-like correlations. Long-range azimuthal correlations are studied differentially as a function of charged particle multiplicity. Those results are compared to event generators and are complementary to the studies of the ridge signals in high multiplicity pp, pA and AA collisions at the RHIC and the LHC.