Wayne State University

Aim Higher


Winter 2017

Unless noted otherwise, these talks are presented in Rm 312, Fridays at 3:30 PM.


Date Speaker Affiliation Title Host


20 Jan


David Cinabro

Wayne State University

Search for Type IA Supernova subclasses

In response to a recently reported observation by Milne and collaborators of evidence for two classes of Type Ia Supernovae (SNe Ia) distinguished by their brightness in the rest-frame near ultraviolet (NUV), I report on a search for the phenomenon in publicly available light-curve data. My collaborators and I use the SNANA supernova analysis package to simulate SN Ia-light curves in the Sloan Digital Sky Survey Supernova Search (SDSS) and the Supernova Legacy Survey (SNLS) with a model of two distinct ultraviolet classes of SNe Ia and a conventional model with a single broad distribution of SN-Ia ultraviolet brightnesses. We compare simulated distributions of rest-frame colors with these two models to those observed in 158 SNe~Ia in the SDSS and SNLS data. The SNLS sample of 99 SNe~Ia is in clearly better agreement with a model with one class of SN~Ia light curves and shows no evidence for the reported distinct NUV sub-classes. The SDSS sample of 59 SNe~Ia with poorer color resolution does not distinguish between the two models.  

David Cinabro

3 Feb - Cancelled 

Feng Li

Frankfurt Institute for Advanced Study

Spinodal Instability in the Baryon Rich Quark Matter

The spinodal instability, i.e. the self-amplified deviation from the equilibrium state during a first order phase transition, of the baryonic rich quark matter is studied by both using the linear response theory and solving the Boltzmann equations with the test particle method. The former approach includes the quantum effect but only works near equilibrium, while the second one is semi-classical but capable of describing a highly non-equilibrated system. In the first approach, we obtain both the spinodal boundaries of the unstable modes of different wavelengths and the growth rates of them at a certain temperature and baryon density in the early stage of phase separation. In the second approach, we study the spinodal instability of the baryonic rich quark matter in both a closed box and an expanding fireball by investigating the time evolution of the quantities such as the scaled density moments, the event distribution of the particle numbers in a sub-volume, the event distribution of the anisotropic flows, and the dilepton yield. 

Shanshan Cao

10 Feb

Jessie Runnoe

University of Michigan

Now you see them, now you don't: the (dis)appearing central engines of changing-look quasars

Changing-look quasars are a newly recognized class of high-luminosity active galactic nucleus where we observe dramatic transitions between "quasar-like" and "galaxy-like" spectral states on timescales of a decade or less. These objects are a challenge to explain in the context of accretion physics and represent unique opportunities to study quasar unification, variability, lifetimes, and feedback. To date, a dozen changing-look quasars have been identified through a combination of serendipitous discovery and systematic searches, and these are likely just the tip of the iceberg. I will describe the results of initial case studies and discuss what we have learned from the growing sample of these objects as well as the prospects for finding and analyzing them in greater numbers in the future.

Ed Cackett

17 Feb


Richard (Rick) Field

University of Florida

Studying the Energy Dependence of the Underlying Event at the Tevatron and the LHC

I will review the CDF “underlying event” (UE) studies at the Tevatron starting with the first studies in 2000 and the first Tevatron QCD Monte-Carlo model tune, PYTHIA Tune A. I will discuss the extrapolation of the CDF Tevatron PYTHIA tunes to the LHC energies. CDF UE data at 300 GeV, 900 GeV, and 1.96 TeV can be combined with LHC data at 7 and 13 TeV allowing for a detailed study of the energy dependence of the various components of the UE at five center-of-mass energies. The CDF 300 GeV and 900 GeV data are a result of the “Tevatron Energy Scan” which was performed just before the Tevatron was shut down. The overall “transverse” region of can be divided into the “transMAX” and “transMIN” contributions. The “transMIN” is very sensitive to the multiple parton interaction component (MPI) of the UE, while “transDIF” (“transMAX” minus “transMIN”) is very sensitive to the initial-state and final-state radiation. The “transMIN” and “transDIF” observables have very different energy dependences. The PYTHIA QCD Monte Carlo model tunes do a fairly good (although not perfect) job in describing the energy dependence of “transMIN” and “transDIF”. I have enjoyed very much being involved with the CDF UE measurements at 300 GeV, 900 GeV, and 1.96 TeV, as well as the more recent CMS UE studies 7 and 13 TeV. Combined Tevatron and LHC UE studies will result in improved QCD Monte Carlo models and more accurate simulations of hadron-hadron collisions. 

Alexey Petrov

17 Feb


Matt Baumgart

Rutgers University

Capture and Decay of Electroweak Wimponium

The spectrum of Weakly-Interacting-Massive-Particle (WIMP) dark matter generically possesses bound states when the WIMP mass becomes sufficiently large relative to the mass of the electroweak gauge bosons. In the specific case of the wino, we find that the rate for bound state formation is suppressed relative to direct annihilation, and so provides only a small correction to the overall annihilation rate. The implications for general nonabelian dark sectors though, show that bound state formation must be considered in any thorough treatment of observability. The soft photons radiated by the capture process and by bound state transitions could permit measurement of the dark matter's quantum numbers.

Gil Paz

24 Feb

Carlos Wagner

Argonne National Laboratory; Enrico Fermi Institute and Kavli Institute for Cosmological Physics, UChicago

Higgs Coupling Measurements and New Physics

Precision measurements of the 125 GeV Higgs resonance recently discovered at the LHC have determined that its properties are similar to the ones of the Standard Model (SM) Higgs boson. However, the current uncertainties in the determination of the Higgs boson couplings leave room for significant deviations from the SM expectations. In fact, if one assumes no correlation between the top-quark and gluon couplings to the Higgs, the current global fit to the Higgs data lead to central values of the Higgs couplings to the bottom-quark and the top- quark that are about 2 σ away from the SM predictions. In this talk we shall discuss theoretical models which could lead to a sizable enhancement (suppression) of the top-quark (bottom-quark) coupling to the Higgs and present some testable implications of these models.
The speaker is the Head of the ANL High Energy Physics Theory Group and Professor at the EFI and the KICP, University of Chicago

Nausheen Shah

3 March

Michael Kohl

Jefferson Lab

Anomalies in fundamental observables - old physics or new physics?

Anomalies in measurements of the proton elastic form factors, the proton charge radius, and the muon magnetic moment have given rise to speculations about missing elements of old or new physics, such as two-photon exchange or the postulation of new particles still to be discovered, which could also be linked to dark matter. A framework of new experiments aims to resolve these puzzles by stringently testing the offered hypotheses. I will discuss aspects of the OLYMPUS, MUSE, TREK and DarkLight experiments and show how they are intertwined.

Gil Paz

10 March

Yu Gao

Wayne State University

Searches for Extra Neutrinos

Extra species of non-Standard-Model neutrinos have been an appealing direction of new physics from both experimental phenomena and several theoretical frameworks. Their possible masses, if accessible to current experiments, can range from the eV scale up to multiples of TeV. For light sterile neutrinos I will discuss the recent developments in their measurement through high-energy atmospheric and very short baseline neutrino oscillations. I will also discuss the searches for heavy extra neutrinos from direct and indirect detection, as well as the prospects of directly probing the heavy neutrinos at the large hadron collider.  

Gil Paz


13 March


Matthias Neubert

Mainz University

LHC probes of axion-like particles

We argue that the study of rare Higgs decays in the high-luminosity run at the LHC can probe axions and axion-like particles (ALPs) in a wide range of parameter space, which is otherwise inaccessible to experimental searches. If the ALP decays predominantly into photons, our strategy covers the current “gap” in the mass range between 1 MeV and 60 GeV down to photon-axion coupling as small as 10^(-6)/TeV. An ALP is this parameter range can explain the anomalous magnetic moment of the muon and is consistent with electroweak precision tests and flavour constraints. In our analysis we consider the most general effective Lagrangian for a spin-0 particle protected by a shift symmetry, motivated by many extensions of the Standard Model with a spontaneously broken global symmetry. 

Gil Paz

24 March


Todd Pedlar

Luther College

Spectroscopy of Heavy Quarkonia and Related States at Belle and Belle II

In this talk, contributions made in the spectroscopy of heavy quarkonium and quarkonium-like states by the Belle Collaboration over the past decade will be discussed. The focus will be on both bottomonium and charmonium-related states including the most recent studies of the charged Zb and Zc states reported in the past few years by Belle. Prospects for further study of these systems in the future Belle II Experiment will also be presented. 

Matt Barrett

31 March

David Gerdes

University of Michigan

The Coolest Place in the Solar System: New Worlds Beyond Neptune and the Hunt for Planet Nine

The region beyond Neptune contains thousands of small, icy worlds that take centuries or even millennia to orbit the Sun. These "cosmic leftovers" constitute an archaeological record of the processes that shaped our Solar System. The objects with the longest orbital periods--some of which have been discovered by my group--display a statistically improbable orbital alignment that may result from the presence of a distant ~10 Earth-mass "Planet Nine". I'll describe how we are using data from the Dark Energy Survey, which was designed for extragalactic astronomy--to make exciting new discoveries in our own backyard, and discuss our ongoing search for Planet Nine.

David Cinabro

7 April

Kirsten Tollefson

Michigan State University 



Robert Harr 

14 April

Amaresh Datta

University of Hawaiʻi at Mānoa

Search for Antideuterons in Cosmic Ray Data from AMS-02 and Understanding the Deuteron/Antideuteron Production Mechanism from NA61 Data

Detection of antideuterons produced from dark matter annihilations or decays are complementary to direct detection techniques that probe the scattering cross-sections of dark matter. Low energy antideuterons are a most interesting probe because of their ultra-low astrophysical background, the dominant source of which are the interactions between cosmic-ray protons and interstellar medium (mostly H, He). High production threshold and a steep cosmic-ray spectrum, however, ensure a low background from such processes. We search for antideuterons in cosmic-ray data recorded by Alpha Magnetic Spectrometer (AMS-02) on board the International Space Station (ISS). Production of antideuterons and deuterons in nuclear interactions is a complex non-perturbative process. Using NA61/SHINE data (at CERN SPS) from p+p interactions with 158 GeV/c beam on liquid H target, we are working towards measurements of cross-sections of deuteron production. Comparison between cross-section measurements with predictions using models of coalescence between protons and neutrons will provide insight into the production mechanism and will help improve models. Extending the analysis techniques, measurements of antideuteron cross-sections will be helpful in limiting astrophysical background in AMS-02 data. 

Sean Gavin

21 April

David McKeen






Fall 2016


Unless noted otherwise, these talks are presented in Rm 312, Fridays at 4:00 PM.

Date Speaker Affiliation Title Host



Thomas Weiler

Vanderbilt University

Trends in Astrophysical Neutrino Data

After many years of waiting we now have a few years worth of astrophysical neutrino data. The “trickle-in” rate of signal events at the largest astro-neutrino detector, iceCube, is about 14events/year. We will discuss the trends exhibited by the ~50 accumulated events. Trends to be discussed include a possible North-South hemispherical asymmetry, an energy break in a single power-law spectrum, extragalactic versus galactic origins, and the possibility for neutrino flavor to shed light on cosmic acceleration mechanisms.

(Truth in advertising: I am not a member of any experimental collaboration.)
Alexey Petrov

Oct 21

4 pm

Roy Briere Carnegie Mellon University

An Overview of BESIII Physics

BESIII began taking physics data on e+e- collisions in the 2-5 GeV energy range in 2009.  I will give an overview of the datasets acquired and review some interesting physics results.  Topics include weak flavor physics with D mesons (including quantum correlations), charmonium results, studies of exotic charmonium states (XYZ), and low-energy hadron physics. 

Alexey Petrov

Nov 4

4 pm

Jacquelyn Noronha-Hostler University of Houston

Going beyond the RAA to v2 puzzle

Event-by-event fluctuations caused by quantum mechanical fluctuations in the wave function of colliding nuclei in ultrarelativistic heavy ion collisions were recently shown to be necessary for the simultaneous description of RAA as well as the elliptic and triangular flow harmonics at high pT in PbPb collisions at the Large Hadron Collider. In fact, the presence of a finite triangular flow as well as cumulants of the flow harmonic distribution that differ from the mean are only possible when these event-by-event fluctuations are considered. In this talk, I combine event-by-event viscous hydrodynamics and an energy loss mode to make predictions for high pT RAA, v2{2}, v3{2}, and v2{4} in PbPb collisions at √sNN = 5.02 TeV. Additionally, new experimental observables are presented that can help distinguish between different energy loss mechanisms.

Sean Gavin


Nov 9

4 pm

Abhishek Sen BNL

Technical challenges understanding heavy ion collisions in experiment and theory

The bulk of hot and dense matter created by heavy ion collisions at RHIC behaves like an almost ideal fluid. In order to understand the hot QCD in detail, we need an analysis of heavy ion collision experimental data and theory, together with the dynamical modeling which connects them. The bridge between theoretical modeling and experimental observations is crucial to draw valid conclusions about the properties of QCD matter. An overview of technical challenges in experiment and theory will be presented.

Abhijit Majumder

Nov 11

4 pm

Abderahmen Zoghbi University of Michigan

Decoding the heartbeats of the Galactic black hole GRS 1915+105

GRS 1915+105 is a Galactic stellar-mass black hole that shows the most extreme variability properties among all known black holes. It shows coherent and stable periodic patterns in its X-ray emission not matched by any other object, which are suggestive of accretion instabilities. The fact that it also shows jets and outflow winds, makes it an excellent laboratory for understanding the stability of the accretion process and the inflow/outflow interaction. I will present results from recent state of the art X-ray observations of this object. We are able, for the first time, to probe changes in the accretion disk during the coherent oscillations, observe changes in the disk content as instabilities progress, and locate where the winds are launched from.

Ed Cackett


2 Dec


Ron Soltz Lawrence Livermore National Laboratory

From Quark Soup to Jets: A peripatetic view of the quark gluon plasma

We review progress in understanding the properties and composition of the Quark Gluon Plasma, from the formulation of QCD through the present, including both successes and failures in developing this understanding. Specific attention is given to measuring and modeling the space-time evolution of the soft physics component before proceeding to describe the current research program which seeks to do the same for the hard/jet physics sector through the JETSCAPE framework under development at WSU.

Abhijit Majumder

Dec 2

4 pm

Masha Baryakhtar Perimeter Institute

Searching for Ultralight Particles with Black Holes and Gravitational Waves

The LIGO detection of gravitational waves has opened a new window on the universe. I will discuss how the process of superradiance, combined with gravitational wave measurements, makes black holes into nature's laboratories to search for new light bosons. When a bosonic particle's Compton wavelength is comparable to the horizon size of a black hole, superradiance of these bosons into bound "Bohr orbitals" extracts energy and angular momentum from the black hole. The occupation number of the levels grows exponentially and the black hole spins down. For efficient superradiance of stellar black holes, the particle must be ultralight, with mass below 10^-10 eV; one candidate for such an ultralight boson is the QCD axion with decay constant above the GUT scale. Measurements of BH spins can disfavor or provide evidence for an ultralight axion. Particles transitioning between levels of the gravitational "atom" and annihilating to gravitons may produce thousands of monochromatic gravitational wave signals, turning LIGO into a particle detector.

Gil Paz


Winter 2016

Unless noted otherwise, these talks are presented in Rm 312, Fridays at 11:40AM.

Date Speaker Affiliation Title Host



Ahmad Idilbi


Hadronic Matrix Elements in (1+2) Dimensions

Hadronic matrix elements with longitudinal and transverse dependence play an important role in a wide variety of QCD related phenomena. Among other things, such quantities are required to address certain issues in hadronic spin physics, to make predictions for the transverse momentum dependent spectrum of the Higgs boson production at the LHC, to obtain three-dimensional hadronic tomography and for jet broadening (and other observables) of jets traversing a hot and dense medium. In my talk I will review the main subtle issues regarding transverse momentum dependent (TMD) functions, how they are resolved and certain properties obtained for the newly defined TMD functions. Especially I will consider generalized TMDs, TMD parton distribution functions and the jet quenching parameter q-hat. Time allows, I will discuss some of the intriguing remaining open questions that span most of the topics mentioned above. 

Abhijit Majumder
Feb-12 Claude Pruneau WSU Bayesian Statistics  




Alejandro de la Puente Carelton Univ.

Compressing the Inert Doublet Model

I will present a study of the Inert Doublet Model in the presence of additional approximate symmetries where the resulting spectrum of exotic scalars can be compressed. In addition, a discrete symmetry to prevent couplings of the new scalars to Standard Model fermions stabilizes the lightest inert state, which can then contribute to the observed dark matter density. I will show you the phenomenological and cosmological implications of this scenario and the new limits we derived on the compressed Inert Doublet Model from LEP. I will then outline the prospects for exclusion and discovery of this model at dark matter experiments, the LHC, and future colliders.

Alexey Petrov
Feb-26  Matt Barrett WSU Particle Identification at Belle II

The Belle II experiment is an upgrade of the Belle experiment that will
run at an instantaneous luminosity forty times higher than its
predecessor, and is projected to record 50 ab-1 of data.  Running at
this luminosity requires many changes, including the installation of new
sub-detectors.  The status of the construction and testing of Belle II
will be described, with a focus on the new time-of-propagation (TOP)
sub-detector used for particle identification, together with the
motivation, prospects, and schedule for the experiment
Dave Cinabro
Mar-4 Richard Lebed Arizona State University

Excursions to Exotic Destinations

Following on from the generalities in my colloquium about the discovery and nature of the newly discovered exotic hadrons, this seminar summarizes my own research in this very active area.  I discuss whether tetraquarks in large Nc QCD arise naturally or not; then I look at the dynamical diquark picture in a bit more detail to summarize its successes and shortcomings; what the "cusp effect" is, and how it can synchronize resonance masses with opening hadron thresholds; how to use the "quark-counting rules" of high-energy QCD to discern exotic structure; whether hidden-strangeness exotics have been seen and where to look for them; and lastly, brand-new work on whether hidden-charm, hidden-strangeness tetraquarks have already been seen.

Gil Paz





Andreas Kronfeld Fermilab

Lattice QCD and Flavor-Changing Neutral Currents

Recent lattice-QCD calculations have improved the precision of several hadronic matrix elements.  Standard Model predictions for several observables (calculated with these results) are in tension with the corresponding experimental measurements.  In the talk, I will give an overview on how lattice QCD calculations are done, using neutral B-meson mixing as a working example.  I will then discuss the phenomenology of B mixing and also semileptonic decays mediated by flavor-changing neutral currents.

Gil Paz
Mar-25 Michael Kordell WSU

Jets in p(d)-A Collisions: Centrality Dependent Effects: Color Transparency or Energy Conservation?

The production of jets, and high momentum hadrons from jets, produced in deuteron (d)-Au collisions at the relativistic heavy-ion collider (RHIC) and proton (p)-Pb collisions at the large hadron collider (LHC) are studied as a function of centrality, a measure of the impact parameter of the collision. A modified version of the event generator PYTHIA, widely used to simulate p-p collisions, is used in conjunction with a nuclear Monte-Carlo event generator which simulates the locations of the nucleons within a large nucleus. We demonstrate how events with a hard jet may be simulated, in such a way that the parton distribution function of the projectile is frozen during its interaction with the extended nucleus. Using our approach, we demonstrate that the puzzling enhancement seen in peripheral events at RHIC and the LHC, as well as the suppression seen in central events at the LHC are mainly due to mis-binning of central and semi-central events, containing a jet, as peripheral events. This occurs due to the suppression of soft particle production away from the jet, caused by the depletion of energy available in a nucleon of the deuteron (in d-Au at RHIC) or in the proton (in p-Pb at LHC), after the production of a hard jet. We conclude that partonic correlations built out of simple energy conservation are mostly responsible for such an effect.

Abhijit Majumder




Peter Schwerdfeger

The New Zealand Institute for Advanced Study, Massey University, Auckland

Beyond the Standard Model - the Variation of Fundamental Constants in Space-Time

Fundamental constants like the speed of light c, the Planck constant h or the gravitational constant G play defining roles in physics and chemistry. Modern theories attempting to unify all four fundamental forces of nature suggest that all fundamental constants may vary in space and time. A small deviation from these constants would result in a completely different universe not able to sustain life. The search for small variations currently constitutes one of the most exciting areas of modern physics as it goes beyond the standard model in particle physics. In fact, this area of research is motivated by new theories unifying gravity with the other three fundamental interactions, as well as by a number of cosmological models. From atomic clock experiments we already know that the variation of the fine structure constant Δα/α is less than ~10-17 per year, and the variation in the electron to proton mass ratio Δμ/μ  (μ=me/mp) is similarly small with less than ~10-15 per year. Quasar and Big Bang nucleosynthesis data gave hints for non-zero variations, which, however, have not been confirmed yet. For further progress in this area it is important to find enhanced effects in atoms or molecules for the variation of fundamental constants. Our research group, in close collaboration with V. V. Flambaum (Sydney) and many others, currently searches for best candidates to measure variations of fundamental constants in future high-precision laboratory experiments.

Bernhard Schlegel, Chemistry
Apr-15 Joshua Spitz U of M

Kaon decay-at-rest and a very unique neutrino

When a charged-kaon decays at rest, it usually (64%) produces a monoenergetic muon neutrino at 236 MeV. Recently, this unique neutrino has been identified as an important tool for studying neutrino oscillations at short baseline, probing the nucleus, and understanding the neutrino interaction itself. I will discuss the "kaon decay-at-rest" concept for neutrino physics and present a set of experiments that will be able to perform the relevant measurements in the next few years.

Gil Paz



3:00 PM

Martin Jung Tech. Univ. Munich Bounds on new physics from electric dipole moments

Electric dipole moments are extremely sensitive probes for additional sources of CP violation in new physics models. The multi-scale problem of relating the high precision measurements with neutrons, atoms and molecules to
fundamental parameters can be approached model-independently to a large extent; however, care must be taken to include the uncertainties from especially nuclear and QCD calculations properly. The resulting bounds on fundamental parameters are illustrated in the context of Two-Higgs-Doublet models.

Alexey Petrov

















Fall 2015

Unless noted otherwise, these talks are presented in Rm 312, Fridays at 10:30AM.

Date Speaker Affiliation Title Host
Sep-18 Clint Young MSU

Electromagnetic recombination spectra at the quark-hadron phase transition

Photons are radiated when quarks and gluons hadronize. This is true not only in jets but also in heavy ion collisions, where a thermalized plasma of quarks and gluons cools into a weakly interacting gas of hadrons. In the quark-meson model at finite temperature, quarks coalesce into pions and radiate like any other accelerating electric charge. The ratio in the yields of these photons to the yields of pions in our simplified model goes roughly as $e^2/g^2_{qbar{q}pi}$. Because $g_{qbar{q}pi}$ is a parameter of an effective theory and is fit to data, this ratio is merely an estimate, but for the standard range of values used, this ratio is 5-10%. The photon production at hadronization of the quark-gluon plasma will be part of the solution to the photon puzzle, both because it enhances the yield of photons at momenta of about 2 GeV/c, and because the photons produced are made at late times and will have significant elliptic flow.

Sean Gavin
Oct-16 Kendall Mahn MSU

New antineutrino oscillation results from the T2K experiment

One of the most promising investigations of beyond-the-Standard-Model physics has been the study of neutrino oscillation, that is, the conversion of neutrinos from one flavor to another as they propagate. While neutrino oscillation is studied in a wide variety of experiments, accelerator based experiments, such as T2K, use a muon neutrino or antineutrino beam as a probe. This talk will describe the first results from T2K for antineutrino disappearance, a test of non-standard matter interactions, and the initial search for electron antineutrino appearance. In particular, the presence of electron antineutrino appearance transition is a necessary requirement for future CPV experiments with neutrinos, and has not been observed yet.

David Cinabro
Oct-23 Ruth Van der Water FNAL

New-Physics Searches in B-meson semileptonic decays with Lattice QCD

B-meson decays provide a wealth of complementary observables that enable tests of the Standard Model and probe different new-physics scenarios, provided sufficiently precise and reliable experimental measurements and theoretical calculations.  Recently several tantalizing 2-3sigma tensions have been observed in B-meson decays; new experimental measurements, including observations of heretofore unseen processes have also appeared.  The Fermilab Lattice and MILC Collaborations recently completed lattice-QCD calculations of the underlying hadronic form factors for B->pi and B->K semileptonic decays.  Here I summarize the numerical form-factor computations and then discuss the phenomenological implications.  Using the FNAL/MILC form factors, I present results for observables in the Standard Model for B→π(K)l+l-, B→π(K)νν̅, and B→πτν  decays.  For B→π(K)l+l-, I then compare the Standard-Model expectations with experimental measurements.  Assuming the Standard Model, I determine the Cabibbo-Kobayashi-Maskawa matrix elements |V_{td}|, |V_{ts}|, and their ratio from B-meson semileptonic decays.  Alternatively, taking the CKM matrix elements from unitarity, I constrain new-physics contributions at the electroweak scale.

Alexey Petrov
Oct-30 Mark Reynolds UM

Probing the Spin Evolution of SMBHs at Cosmological Distances

The co-evolution of a super-massive black hole (SMBH) with its host galaxy through cosmic time is encoded in its spin. At z>2, super-massive black holes are thought to grow mostly by merger-driven disk accretion leading to high spin. It is not known, however, whether below z<1 these black holes continue to grow in this way (so called coherent accretion) or instead in a less organized more erratic manner (chaotic accretion). An established method of measuring the spin of black holes is through the study of relativistic reflection features from the inner accretion disk. I will present recent work wherein we have for the first time directly measured the spin of cosmologically distant SMBHs, by taking advantage of the boost in S/N provided by the strong gravitational lensing of distant Quasars.

Ed Cackett
Nov-13 Sarah Gallagher University of Western Ontario

Winds, Winds Every Where: Radiatively Driven Outflows from Supermassive Black Holes

Supermassive black holes reside in the centers of every massive galaxy. In relatively brief spurts, black holes grow as luminous quasars through the infall of material through an accretion disk. Remarkably, the light from the accretion disk can outshine all of the stars in the host galaxy by a factor of a thousand, and this radiation can also drive energetic mass outflows. Mass ejection in the form of winds or jets appears to be as fundamental to quasar activity as accretion, and can be directly observed in many objects with broadened and blue-shifted UV emission and absorption features. A convincing argument for radiation pressure driving this ionized outflow can be made within the dust sublimation radius. Beyond, radiation pressure is still important, but high energy photons from the central engine can now push on dust grains. This physics underlies the dusty wind picture for the putative obscuring torus. I'll describe our model of the dusty wind and evaluate its successes and shortcomings in accounting for observed properties of quasars such their mid-infrared power, fractions of hidden objects, and column densities of important ions.

Ed Cackett
Nov-20 William Wester III FNAL

Non-WIMPy Dark Matter Searches at Fermilab

"What is the nature of Dark Matter" that accounts for approximately 80% of the matter in the universe? Gaining popularity is to invoke the possibility that "Non-WIMPy" new particles form the dark matter in contrast to usual Weakly Interacting Massive Particles hypothesis. Novel ideas and novel experiments, often at a very small scale, are exploring large areas of previously unexplored parameter space. Plus, they are a lot of fun too!

Rob Harr
Dec-4 Mike Lisa tOSU

Global Hyperon Polarization in Ultra-relativistic Heavy Ion Collisions Measured by the STAR Experiment at RHIC

Non-central collisions between ultra-relativistic heavy ions involve millions of h-bar of angular momentum.  It is unclear how much— if any— of this angular momentum is transferred to the quark-gluon plasma created at midrapidity.  Such a transfer may arise via a spin-orbit coupling in QCD or, in a hydrodynamic picture, through shear forces that generate a vorticity in the fluid.  While thermalization of energy and light-flavor chemical degrees of freedom in heavy ion collisions is well-established, thermal distribution of angular momentum among all available substates is far from clear.  Angular momentum thermalization or vorticity in the QGP may result in a correlation between the spin of emitted hadrons and the direction of the angular momentum of the overall system.  This “global polarization” is distinct from polarization relative to the particle production plane observed at very forward angles in p+p collisions.  Due to their so-called self-analyzing nature, hyperons reveal their spin orientation in their decay.  STAR has measured the first non-zero signal of the polarization of Lambdas and AntiLambdas relative to the direction of the collision’s angular momentum, estimated by the event reaction plane, at several collision energies.  I will discuss details of the analysis, the energy and centrality dependence of the signal, and two methods of quantifying the polarization.  I will also discuss detector and accelerator upgrades that will allow us to study this new signal in far greater detail in the upcoming second phase of the Beam Energy Scan at RHIC.

Sergei Voloshin

Unless mentioned otherwise, talks are presented in Rm 312 at 3PM.

Date Speaker Affiliation Title Host
Feb 6th Professor Anne Sickles University of Illinois at Urbana-Champaign

The Lighter Side of Heavy Ion Collisions: What have we learned from colliding large nuclei with protons, deuterons and He3?

The stated goal of heavy ion physics is to produce and study the high temperature state of quantum chromodynamics where quarks and gluons are not confined inside hadrons, the quark gluon plasma.  Large nuclei are used to maximize the size of the created matter. Asymmetric collisions, where a proton or deuteron collides with a large nucleus have been used to study modifications to the bound nucleons in nuclei in the absence of the quark gluon plasma  Recent measurements from both RHIC and the LHC show effects very similar to those seen in heavy ion collisions which are attributed to the quark gluon plasma.  I’ll discuss the experimental situation, including very recent results on He3+Au collisions from PHENIX.

Feb 20th Dr.  John R. Arrington

Argonne National Laboratory

"Nucleon form factors: detours, U-turns, roundabouts, and a head-on collision"


"Jefferson Lab experiments utilizing polarization degrees of freedom to extract proton and neutron form factors have dramatically changed our understanding of the structure of nucleons.  These experiments have illuminated the role of quark orbital angular momentum, allowed for the separation of up- and down-quark distributions, and demonstrated the importance of diquark correlations in proton structure.  However, it has been a somewhat bumpy ride: the first polarization measurements of the proton form factors at high Q^2 showed a discrepancy with earlier unpolarized extractions, leading to a detailed theoretical and experimental reexamination of two-photon exchange contributions. More recently, ultra-precise measurements of the proton radius from muonic hydrogen are at odds with extractions from electron scattering.  I will summarize the Jefferson Lab form factor program, covering what we have learned about the structure of the proton, recent results on two-photon exchange corrections and future plans aimed at resolving the proton radius puzzle."

March 6th Scott Pratt Michigan State University

Have we finally “Seen” the Quark Gluon Plasma?

For the past 20 years experiments have attempted to create and observe the quark gluon plasma in heavy ion collisions, but it has proven difficult to quantitatively characterize its properties from experimental observation. However, during the last few years a new class of experimental observations based on correlations driven by local charge conservation is proving to be able to address one of our most fundamental questions about the chemical makeup of matter created in heavy ion collisions: “Does it have the properties, e.g. the density of quarks, one would expect from an equilibrated quark gluon plasma. I will show how charge balance functions measured by STAR  at the Relativistic Heavy Ion Collider can be interpreted by simple models and infer charge susceptibilities. These will then be compared to values extracted from lattice gauge theory.


April 3rd

Michael Ramsey-Muslof


To be confirmed.

April 10th Dr.Mauricio Martinez Guerrero The Ohio State University Testing hydrodynamics with a new exact solution of the Boltzmann equation

We present an exact solution to the Boltzmann equation which describes a system undergoing boost-invariant longitudinal and azimuthally symmetric radial expansion for arbitrary shear viscosity to entropy density ratio. This new solution is constructed by considering the conformal map between Minkowski space and the direct product of three dimensional de Sitter space with a line. The resulting solution respects SO(3)_q x SO(1,1) x Z_2 symmetry. We compare the exact kinetic solution with exact solutions of the corresponding macroscopic equations that were obtained from the kinetic theory in ideal and second-order viscous hydrodynamic approximations. The macroscopic solutions are obtained in de Sitter space and are subject to the same symmetries used to obtain the exact kinetic solution.

April 17th Professor Thomas Schwarz University of Michigan

Searching for Dark Matter with CCD's on the DAMIC Experiment





Fall Term 2014

Seminars are held on Friday at 4:00 pm in Room 312 of the Physics Research Bldg. unless otherwise noted.





Subject or Title of Talk


Sep. 17 (Wed.) 4 p.m.


Daniel Cebra

Univ. of California, Davis

beam energy scan at RHIC

Rosi Reed

Sep. 24 (Wed.) 4 p.m.   


Itay Yavin

McMaster Univ. & Perimeter Institute

particle theory

Gil Paz

Sep. 26 (3 p.m.)


Jay Strader

Michigan State Univ.

black holes in globular clusters

Ed Cackett

Oct. 03 (3 p.m.)


Misty Bentz

Georgia State Univ.

Black Hole Masses in Active Galaxies

Ed Cackett

Oct. 08 (11 a.m.)


Daniel McKinsey

Yale Univ.

Low-Energy Ionization and Scintillation Response of Liquefied Noble Gases

Gil Paz

Oct. 31 (3 p.m.)


Chia-Ying Chiang

Wayne State Univ.

Modeling the X-ray Spectra of AGN with a Relativistic Reflection Model

Ed Cakett

Nov. 05 (Weds.)


Minakshi Nayak

Wayne State Univ.

Evidence of the suppressed decay B- to D K-, D to K+ pi- pi0

David Cinabro

Nov. 14


Andre de Gouvea

Northwestern Univ.

Fundamental Physics with Muons

Gil Paz

Dec. 05


Sudeshna Ganguly

Wayne State Univ.

Measurement of branching fractions of rare semi-leptonic D_s decays at

Giovanni Bonvicini