# Upcoming Events

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### The wool over our eyes: how scientists think they and their institutions are objective, but aren’t by Brian Nord

Apr 28, 2017, 2:00 PM-3:00 PM

Room: 202 Physics Bldg.

CM

### Morphogenesis of the first branchial arch - by Sevan Hopyan

Apr 28, 2017, 11:00 AM-12:00 PM

Rooms 202/204

Host: Cristina Marchetti | Contact: Tyler Engstrom, taengstr@syr.edu

The nuanced shapes of emerging organ primordia are intimately related to pattern formation and postnatal function, although the mechanisms that shape a volume of tissue in the embryo are not well understood.  The mandibular portion of the first branchial arch is composed of a volume of mesenchyme surrounded by a single cell layer epithelium.  Here we ask how this structure acquires a proximally narrow and distally bulbous shape during outgrowth.  Using the mouse embryo as a model system, we measured cell cycle times, as well as Young’s modulus and viscosity using atomic force microscopy.  Incorporating these data into a finite element model, we show that the spatial variation of cell division and physical properties is insufficient to explain mandibular arch shape.  By combining time lapse light sheet microscopy of intact mouse embryos with custom cell tracking, we observed that volumetric convergent extension due to the intercalation of mesenchymal cells in 3D likely underlies the narrow and elongate shape of the mandiublar arch mid-portion.  By knocking-in a transgenic FRET-based vinculin tension sensor into the mouse genome, we show that relatively high amplitude cortical force oscillations correlate with mesenchymal cell intercalations, and are oriented by polarised actomyosin.  Evidence from loss and gain of function studies suggest that Wnt5a acts as a directional cue to regulate both the orientation and oscillation amplitude of cell cortices.

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### Our Warped Universe: Strong Lensing and Deep Machine Learning in Modern Cosmology Surveys by Brian Nord

Apr 27, 2017, 3:30 PM-5:00 PM

202 Physics Bldg.

Refreshments at 3:30 pm and the talk starting at 3:45 pm

Host: Prof. Scott Watson / Contact: Yudaisy Salomón Sargentón, 315-443-5960

Current and future galaxy surveys will provide data sets unprecedented in size and precision with which to measure dark energy, dark matter and the early universe through probes like strong gravitational lensing. I will discuss our progress in the Dark Energy Survey (DES) to detect, spectroscopically confirm, and characterize lenses. Then, we’ll look at the oncoming era of astronomically big data. Specifically, we’ll discuss techniques, results, and the potential of deep machine learning in its application to cosmology.

TD

### Early universe cosmology as a probe of fundamental physics by Ogan Ozsoy

Apr 26, 2017, 2:30 PM-4:00 PM

Room: 202 Physics Bldg.

Advisor: Prof. Scott Watson / Contact: Yudaisy Salomón Sargentón, 315-443-5960

The features of the universe we probe today are a reflection of the underlying physics at high energies and is a powerful motivation that drives theoretical research in modern cosmology. Precision observations of the Cosmic Microwave Background Radiation and the Large Scale Structure in the universe have already taught us a great deal about what may have occurred at high energies and early times in the universe’s history. In particular, the inflationary paradigm and the existence of cold dark matter stands as the two main pillars of standard model of cosmology (LCDM) which constitutes much of our modern understanding of the world we see today from a cosmological perspective. Despite the successful reconciliation of these theoretical ideas with precision data, we are far from a complete understanding of the particle physics nature of dark matter, inflationary dynamics and how the post-inflationary evolution proceeds. In this talk, I will present several theoretical ideas motivated by bottom-up and top-down constructions in field theory and explore their observational consequences in the hope of shedding some light on these phenomena.

TD

### Defects and Rearrangements in Disordered Solids by Sven Wijtmans

Apr 26, 2017, 9:30 AM-11:30 AM

Room: 202 Physics Bldg.

Advisor: Prof. Lisa Manning / Contact: Yudaisy Salomón Sargentón, 315-443-5960

In this thesis, I will investigate the properties of disordered materials under strain.  Disordered materials encompass a large variety of materials, including glasses, polymers, and gels.  There is currently no constitutive equation that describes these materials. Given the prevalence and usefulness of these materials, we derive tools to aid our understand of them.

We develop a new method to isolate localized defects from extended vibrational modes in disordered solids.  This method augments particle interactions with an artificial potential that acts as a high-pass filter: it preserves small-scale structures while pushing extended vibrational modes to higher frequencies.  The low-frequency modes that remain are bare" defects; they are exponentially localized without the quadrupolar tails associated with elastic interactions. We demonstrate that these localized excitations are excellent predictors of plastic rearrangements in the solid. We characterize several of the properties of these defects that appear in mesoscopic theory of plasticity, including their distribution of energy barriers, number density, and size, which is a first step in testing and revising continuum models for plasticity in disordered solids.

We study rearrangement types in disordered packings of particles with a harmonic potential at a range of packing fractions above jamming.  We develop a generalizable procedure that classifies events by stress drop, energy drop, and reversibility under two protocols.  We find a large population of contact change events that have no associated stress drop. Reversible events become more common at high pressures above a packing fraction of $\phi=0.865$, at which point line reversible events are more common than loop reversible events. At low pressures, irreversible events are associated with spatially extended events, while at high pressures reversible events are much more spatially localized.

HE

### TBD by Prateek Agrawal

Apr 24, 2017, 2:00 PM-3:00 PM

202 Physics Bldg.

Host: Prof. Jay Hubisz / Contact: Yudaisy Salomón Sargentón, 315-443-5960

CM

### Geometry of twisted filaments - by Arshad Kudrolli

Apr 21, 2017, 11:00 AM-12:00 PM

Rooms 202/204

Host: Joseph Paulsen | Contact: Tyler Engstrom, taengstr@syr.edu

We will discuss the fundamental interplay of geometry, elasticity, and
applied stress in determining the hierarchical shapes and mechanical
response of slender elastic materials. A ribbon under a subtle
combination of tension and twist can transform into a rich variety of
shapes including helicoids, triangular folds, tubes, plectonemes,
scrolls, and self-wrapped disordered crumpled structures. The
nucleation topological defects and the growth of wrinkles will be
analyzed with a far-far-threshold approach. We will then examine the
interaction between a set of uniform fibers which are twisted starting
from a hexagonal lattice arrangement. The non-Euclidean geometry of
twisted fiber bundles are an important motif in materials ranging from
cables to textiles and tissues. The evolution of defects as a function
of twist will be examined in light of a new model of the fiber bundle
structure.

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### Reviving Creativity in Our Introductory Physics Labs by Mats Selen

Apr 20, 2017, 3:30 PM-5:00 PM

202 Physics Bldg.

Refreshments at 3:30 pm and the talk starting at 3:45 pm

Host: Prof. Gianfranco Vidali / Contact: Yudaisy Salomón Sargentón, 315-443-5960

Approaching a question without fear; coming up with an idea; designing an experiment; understanding assumptions; interpreting data and revising the idea (or the question) accordingly. Many physicists would claim they do this for a living, and most would be delighted to observe this behavior in their students, yet for a variety of reasons this is often not what we encourage in our introductory physics labs.

We have developed a portable wireless lab system with the goal of putting simple yet powerful tools in the hands of every student, and we are currently piloting a new design-based approach to our introductory physics labs based on this tool. Our students invent experiments and acquire data, both in and out of the classroom, and share their data with each other and with instructors using an integrated cloud based repository. This new approach is allowing us to shift the focus of our introductory labs toward creativity, design, sense-making, and communication. I will describe this project and present some encouraging first results.

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### The Turbulent Vacuum by A.P. Balachandran

Apr 14, 2017, 12:00 PM-2:00 PM

208 Physics Bldg.

Host: Prof. Simon Catterall / Contact: Yudaisy Salomón Sargentón, 315-443-5960

*The following work is jointly done with M.Asorey, F.Lizzi and G.Marmo.

The vacuum state in relativistic quantum field theory is often pictured as devoid of striking properties, as vacuous. But instead the following are true :

1) Atoms or measuring apparatus inserted at space-like distances in vacuum should exhibit no correlations in the above image of the vacuum. But instead if they have localised states with orthogonal wave functions, and atom 1 is in ground state and 2 in an excited state at a space-like distance, either 1 will *never *be affected by 2 via photon emission (which is absurd) or it will be *instantaneously* affected violating causality.

2) Fields in a finite region, no matter how small, acting on the vacuum can produce *any* state in the Hilbert space.

3) Invariance of the vacuum is invariance of the world. (Coleman).

4)There are * no *localised detectors ! ( Implications for a causal quantum information theory ?)

After discussions of the above, we apply them to the Rindler wedge. There we show that photon  or graviton *cannot* be confined to the wedge : there is information leakage out of the wedge (but no unitarity violation). This happens because in qed  and gravity , infrared effects break ( asymptotic ) Lorentz invariance . The above result has potential applications to black hole information paradox. The super selection rules in the two cases are charge and momentum conservation respectively.

CM

### The geometry and topology of granular matter - by Daniel Sussman

Apr 14, 2017, 11:00 AM-12:00 PM

Rooms 202/204

Host: Jen Schwarz | Contact: Tyler Engstrom, taengstr@syr.edu

The fact that granular systems are nearly always perched on the verge of mechanical instabilities lends them many surprising material properties; these properties in turn inform phenomena ranging from earthquakes to soft robotics. The jamming transition provides a useful framework for understanding granular matter as well as a wide class of soft matter systems, and computational methods are a natural candidate to study these strongly correlated many-body systems. In this talk I will discuss how the combination of computational techniques with geometrical and topological approaches – including ideas inspired by topological insulators – can teach us something new about both the jamming transition and the rich phenomena of jammed matter itself, as well as potentially lead to the creation of novel mechanical metamaterials.

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### Massive Gravity and Time-Dependent Black Holes by Rachel Rosen

Apr 13, 2017, 3:30 PM-5:00 PM

202 Physics Bldg.

Refreshments at 3:30 pm and the talk starting at 3:45 pm

Host: Prof. Scott Watson / Contact: Yudaisy Salomón Sargentón, 315-443-5960

The predictions of General Relativity (GR) have been confirmed to a remarkable precision in a wide variety of tests.  Consistent and well-motivated modifications of GR have been notoriously difficult to obtain.  However, in recent years a compelling theory has been shown to be free of the traditional pathologies.  This is the theory of massive gravity, in which the graviton is described by a massive spin-2 particle.  In this talk I will give a brief review of recent developments in massive gravity.  I will then present new results concerning intriguing features of black holes in this theory.

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### Why Black Holes Matter by Prof. Paul Souder

Apr 8, 2017, 9:00 AM-1:00 PM

Aurora Inn (391 Main St., Aurora) on Cayuga Lake

The intriguing and fascinating world of black holes is the subject of a lecture by nuclear physicist Paul Souder, benefitting the Southern Cayuga Planetarium and Observatory in Aurora, New York.

Souder, a professor of physics at Syracuse University, will deliver a multimedia presentation titled “Why Black Holes Matter” on Saturday, April 8, at 11 a.m. at the historic Aurora Inn (391 Main St., Aurora) on Cayuga Lake. He will provide an overview of black holes, as well as share some recent findings, including the discovery of a rare, medium-weight black hole.

The event is open to the public; however, registration is required. Tickets are $45, and include the lecture, lunch and a silent auction. To register, please call 315.685.7163, or send a check, payable to “Friends of the Southern Cayuga Planetarium,” to P.O. Box 186, Aurora NY 13026. Seating is limited; tickets also are available at the door, while supplies last. Following the lecture, attendees are entitled to a free private tour of MacKenzie-Childs, a Victorian farm that produces high-end tableware and home furnishings, and a$5 wine tasting at Bet the Farm Winery and Gourmet Market.

HE

### A Nonperturbative Regulator for Chiral Gauge Theories

Feb 22, 2016, 2:00 PM-4:00 PM

202 Physics

Host: Jay Hubisz, jhubisz@syr.edu | Contact: David Schaich, daschaich@gmail.com

I discuss a new proposal for nonperturbatively defining chiral gauge theories, something that has resisted previous attempts. The proposal is a well defined field theoretic framework that contains mirror fermions with very soft form factors, which allows them to decouple, as well as ordinary fermions with conventional couplings. The construction makes use of an extra dimension, which localizes chiral zeromodes on the boundaries, and a four dimensional gauge field extended into the bulk via classical gradient flow. After explaining the set up, I consider open questions, such as the effects of topological gauge configurations and the viability of these theories, as well as possible exotic phenomenology in the Standard Model lurking at the low energy frontier.

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### LIGO Observation

Feb 18, 2016, 3:45 PM-5:45 PM

202/204 Physics

(refreshments 3:30pm)

Contact: Yudaisy Salomon Sargenton, yssargen@syr.edu

To follow up on the public announcement last week, the LIGO faculty tomorrow will present scientific information about the observation of gravitational waves. You are all invited tomorrow, with refreshments at 3:30 and the presentation starting at 3:45, Thursday, Feb. 18, to learn more about this discovery.

HE

### New Possibilities with Top Partial Compositeness

Feb 15, 2016, 2:00 PM-4:00 PM

202 Physics

Host: Jay Hubisz, jhubisz@syr.edu | Contact: David Schaich, daschaich@gmail.com

I will review the content of 1501.03818 and 1511.05163. Top partial compositeness is a common feature of composite Higgs models. We study the case where masses for lighter quarks are generated through a different mechanism and we discuss the impact of the experimental constraints on the model, in a specific realization with a pseudo Nambu Goldstone boson Higgs. We show that there is no need for flavor symmetries is the up sector, while in the down sector a certain degree of alignment is required. We finally comment on model building aspects, introducing new physics sector with light top partners candidates, relating their lightness to 't Hooft anomaly matching condition.

CM

### The Large-Scale Thermal Stiffening of Graphene Ribbons

Feb 12, 2016, 11:00 AM-1:00 PM

202/204 Physics

Host: Mark Bowick | Contact: Yudaisy Salomon Sargenton, yssargen@syr.edu

We use molecular dynamics to study the vibration of a thermally fluctuating 2D elastic membrane clamped at both ends. We identify the eigenmodes from peaks in the frequency domain of the time-dependent height and track the dependence of the eigen-frequency of a given mode on the bending rigidity of the membrane. We find that the effective bending rigidity tends to a constant as the bare bending rigidity vanishes, supporting theoretical arguments that the macroscopic bending rigidity of the membrane as a whole arises from a strong renormalization of the microscopic bending rigidity. Experimental realizations include two-dimensional atomically thin membranes such as graphene and molybdenum disulfide or polymerized membrane ribbons.

HE

### EFT of Large Scale Structure, Symmetries and Constraints

Feb 8, 2016, 2:00 PM-4:00 PM

202 Physics

Host: Scott Watson, gswatson@syr.edu | Contact: David Schaich, daschaich@gmail.com

I will briefly introduce EFT of large scale structure (LSS) as a systematic perturbative approach to study structure formation. I will identify the symmetries and unique features of the system which determine the structure of EFT expansion. I will show how these symmetries can be used to make non-perturbative predictions about the baryon acoustic peak in the matter correlation function. Finally, I will show how EFT allows us to get unbiased constraints on cosmological parameters such as primordial non-Gaussianity and Neutrino masses from LSS surveys.

HE

### Cosmology in Standard Einstein Gravity with Non-Standard Scalar Field Fluids

Feb 5, 2016, 12:30 PM-2:30 PM

208 Physics

Host: Scott Watson, gswatson@syr.edu, 315-443-8280

I will discuss cosmological solutions in standard Einstein gravity sourced by non-standard, non-canonical scalar field fluids. With recent experimental data from Planck, BICEP2, and the Keck Array now putting stress on the simplest inflationary models, there is a growing need for alternative early universe scenarios. Examples of such fluids include k-essence, DBI, Galileon fields, Horndeski models and the 'new oscillatory' models recently proposed by Nobel Laureate Wilczek et al. I will focus on the stability of these fluids emphasizing the common occurrence of negative kinetic energy degrees of freedom (ghosts), gradient instabilities (imaginary sound speed), superluminal propagating modes and singularities. Cosmological scenarios I will discuss include K-inflation, Galilean Genesis super-inflation, and the G-bounce model.

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Contact Information:
David Schaich, Series Director
daschaich@gmail.com
315-415-3277

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### The Fluid Boundary - Considering Cell Membranes from a Soft Matter Perspective

Feb 4, 2016, 3:45 PM-5:45 PM

202/204 Physics

(refreshments 3:30pm)

Host: Cristina Marchetti

The plasma membrane surrounding cells is composed of lipids and proteins, and is coupled to cytoskeletal fibers and to extracellular matrix. The mixture of lipids that makes up most cell membranes is fluid, forming a liquid film. As a consequence of this fluidity, flow near a membrane can induce a sympathetic flow of lipids and membrane proteins. I will discuss experiments demonstrating this lipid mobility in immobile membranes, and show that fluid flow can be used to advect proteins within lipid bilayers, producing a local concentration gradient.

http://www.damtp.cam.ac.uk/people/a.honerkamp-smith/

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Contact Information:
yssargen@syr.edu
315-443-3901

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### Elasto-capillarity - A New Toolkit for Directed Assembly of Advanced Materials

Jan 28, 2016, 3:45 PM-5:45 PM

202/204 Physics

(refreshments 3:30pm)

Host: Cristina Marchetti

The opportunities for guiding assembly using elastic energy stored in soft matter are wide open. The emerging scientific frontiers in this field show an exceptional promise for significant new applications. Since soft materials can be readily reconfigured, there are unplumbed opportunities to make responsive devices including smart windows for energy efficiency, and responsive optical structures. In the other hand, the trapping of colloidal objects at interfaces between immiscible fluids has proven to exhibit incredible abilities to template the arrangement of particles into rich ordered structures. These structures are controlled by lateral forces that compete with capillary forces. However, these interactions are still unexplored when particles are trapped at the interface of an ordered fluid. In this talk, I will present recent progress in understanding the mechanisms that govern interactions between particles at liquid crystal interfaces. I will report how the resulting potential induced by the interplay between elasticity and capillarity could lead to new opportunities for genuine spontaneous self-assembly and create new strategies for making new generation of advanced materials that may find relevance in many applications in the field of energy technology.

http://magharbi.wordpress.com/

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Contact Information:
yssargen@syr.edu
315-443-3901

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### Good Defects or What Confined Liquid Crystals Can Do

Jan 21, 2016, 3:45 PM-5:45 PM

Room 202/204

(refreshments 3:30pm)

Host: Cristina Marchetti

Liquid crystals are best known for their use in displays, but their interest extends far beyond. This phase of matter, intermediate between liquid and solid, is composed by anisotropic rod-like molecules which spontaneously align in space. When the molecules cannot achieve a perfect order, they form topological defects, mathematical objects which can be used as physical objects for many purposes. I show two examples of how liquid crystal defects can inspire concepts for new materials. The first example is a bistable system, obtained by confining liquid crystals in a micron-sized cubic scaffold. The device can switch between bright and dark metastable states, thanks to the interaction of the defects with the scaffold. The second example is a self-assembled structure of liquid crystal defects that act as micro-lenses. The structure resembles an insect compound eye, able to focus objects at different distances and sensitive to the polarization of light.

Figure 1: Top panel: stable bright and dark states of a display pixel obtained by changing the topological defects. Bottom panel: self-assembled defects around a central pillar. Each defect act as a micro-lens.

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Contact Information:
yssargen@syr.edu
315-443-3901

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### Physics of Cells - Turning Protein Networks into Active Materials

Jan 19, 2016, 3:30 PM-6:00 PM

Room 202 and 204 Physics

NOTE: Tuesday Colloquium

Yudaisy Salomon Sargenton, yssargen@syr.edu

Cells are densely packed collections of proteins. By regulating the organization and interaction of these proteins in both space and time, cells turn collections of molecules into networks with various material properties. Here I will discuss how these networks allow cells to generate force and change shape, and the approaches we use to measure their behavior. Finally I will discuss ways in which we can perturb the system using light to spatially control the activity of the component proteins. http://home.uchicago.edu/~poakes/

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Contact Information:
yssargen@syr.edu
315-443-3901

C

### Photoproduction of Scalar Mesons, and Upgrade of the CLAS Electromagnetic Calorimeter at Jefferson Lab

Jan 5, 2016, 10:30 AM-12:30 PM

202 Physics

Host: Sheldon Stone

The standard quark model makes no allowance for the existence of gluons outside hadrons; however lattice QCD calculations predict bound states of two or more gluons, called glueballs. According to lattice calculations, the lightest of these experimentally unverified particles is expected to have mass in the range of 1−1.8 GeV and JPC = 0++. Themixing of glueball states with neighbouring meson states complicates their identification. The f0(1500) is one of several candidates for the lightest glueball, whose presence in the K0 sK0 s channel was investigated in photoproduction using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. This was done by studying the reaction, γp → fJp → K0 sK0 s p → 2(π+π−)p using data from the g12 experiment. A moments analysis was performed on this data to characterize the spin properties of the resonance observed at 1.5 GeV. Results from the analysis of this data will be presented.

The g12 experiment ran with the CLAS6 detector, so named because of its capability to work with a maximum electron beam energy of 6 GeV. Jefferson Lab has since upgraded its facility to produce electron beam with double that energy. The higher beam energy means that the energy of electrons and photons impinging on the detector will be too high to be contained by the existing CLAS6 electromagnetic calorimeter (EC). Several of the experiments commissioned to be performed using CLAS12 require the accurate detection of neutral pions via their decay into two photons. At the energies of CLAS12, the calorimeter needs to have a very good position resolution in order to be able to detect these two photons and to avoid their labeling as a single photon. It was thus necessary to update the detector sub-system in order to improve its functionality at higher energies. To do this, another calorimeter, the preshower calorimeter (PCAL) is to be placed in front of the EC, the testing and construction of which will be discussed.

TD

### Thesis Defense - Vortices and Quasiparticles in Superconducting Microwave Resonators

Dec 11, 2015, 2:00 PM-4:00 PM

208 Physics

HE

### Neutral B and Bs Meson Mixing from Lattice QCD

Dec 11, 2015, 12:30 PM-2:30 PM

208 Physics

Host: Jack Laiho, jwlaiho@syr.edu, 315-443-0317

Neutral B(s) meson mixing occurs via flavor-changing neutral currents.  In the standard model of particle physics this requires quantum fluctuations, or loop diagrams, making the required interactions improbable --- opening the door for the possibility of discernible effects from new physics.  There are impressive experimental results in B(s) mixing, with the oscillation frequency between B(s) and anti-B(s) mesons measured with better than sub-percent precision.  To better leverage such experimental results in the search for new physics, hadronic contributions must be determined with improved precision.  We will discuss an ongoing, nearly complete, lattice QCD calculation of the hadronic matrix elements needed to describe mixing in and beyond the standard model.  This work is being carried out by the Fermilab Lattice and MILC collaborations on the MILC Nf=2+1 asqtad gauge field ensembles, including four lattice spacings and numerous light quark masses to permit controlled extrapolations to real-world values.

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Contact Information:
David Schaich, Series Director
daschaich@gmail.com
315-415-3277

TD

### Thesis Defense - Understanding Disordered Systems Through Numerical Simulation and Algorithm Development

Dec 10, 2015, 2:00 PM-4:00 PM

208 Physics

C

### First-Principles Determination of Hadronic Contributions to the Muon Anomalous Magnetic Moment

Dec 7, 2015, 2:00 PM-4:00 PM

202 Physics

Host: Jack Laiho, jwlaiho@syr.edu, 315-443-0317

In order to match the increased precision of the upcoming Fermilab E989 experiment, a more precise determination of hadronic contributions to the muon anomalous magnetic moment is needed.  I will present recent progress in a first-principles determination of both the hadronic vacuum polarization and the hadronic light-by-light contribution.

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Contact Information:
David Schaich, Series Director
daschaich@gmail.com
315-415-3277

CM

### DNA as a Sensor of Hg Nanoparticles

Nov 30, 2015, 11:30 AM-1:30 PM

202/204 Physics

Host: Cristina Marchetti

**NOTE: MONDAY SEMINAR**

Biomolecules can be used to provide control in organizing technologically important objects into functional nano-materials.

The interaction between biomolecules and inorganic materials is fundamental to these applications. These studies are expected to play role in the design of novel hybrid materials and new sensors for biological and non-biological objects. In our study we have utilized the DNA in two folds. Firstly we useDNA to fabricate self-assembled nanostructures of Hg. Secondly we demonstrate that the DNA can be used as a sensor of Hg nanoparticles. Mercuric nanoparticles (NP) have been fabricated within the DNA scaffold by site specific interactions. The NP get embedded within double helix and exclusively interact with the nucleic acid of DNA, having no influence on the phosphate backbone of DNA. Furthermore, conjugation of Hg NP with DNA exhibits a rectifying transport behavior, with the unreacted DNA displaying the ohmic behavior.

Formation of metal-base complexes as well as the modifications in transport (electrical) properties of DNA can be utilized as sensor of mercury contamination.

Shikha Varma homepage

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Contact Information:
shdavis@syr.edu
315-443-5960

HE

### Freeze-In Dark Matter with Displaced Signatures at Colliders

Nov 23, 2015, 2:00 PM-4:00 PM

202 Physics

Host: Jay Hubisz, jhubisz@syr.edu, 315-443-2653

Freeze-in is a general and calculable mechanism for dark matter production in the early universe. Assuming a standard cosmological history, such a framework predicts metastable particles with a lifetime generically too long to observe their decays at colliders. In this talk, I will consider alternative cosmologies with an early matter dominated epoch, and I will show how the observed abundance of dark matter is reproduced only for shorter lifetimes of the metastable particles. Famous realization for such a cosmology are moduli decays in SUSY theories and inflationary reheating. Remarkably, for a large region of the parameter space the decay lengths are in the displaced vertex range and they can be observable at present and future colliders. I will conclude with an example of DFSZ SUSY theories where this framework is realized.

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Contact Information:
David Schaich, Series Director
daschaich@gmail.com
315-415-3277

HE

### The Vector Portal at the LHC

Nov 20, 2015, 12:30 PM-2:30 PM

208 Physics

Host: Jay Hubisz, jhubisz@syr.edu, 315-443-2653

An emerging paradigm in particle physics is the possibility that new matter resides in its own sector — a Dark Sector (DS) — connected to the Standard Model via a portal. In this talk I will focus on a well-motivated example of such a scenario: the vector portal. I will discuss two distinct phases of the theory. In one, matter in the DS is a viable candidate for Dark Matter, giving rise to striking new signals at the LHC. In the other phase of the vector portal, matter in the DS can instead acquire a milli-charge under electromagnetism. I will then discuss a recent proposal to look for milli-charges at the LHC.

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Contact Information:
David Schaich, Series Director
daschaich@gmail.com
315-415-3277

CM

### TBA

Nov 20, 2015, 11:00 AM-1:00 PM

202/204 Physics

Host: Britton Plourde

Matteo Mariantoni web page

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Contact Information:
shdavis@syr.edu
315-443-5960

C

### Inside Physical Review Letters

Nov 19, 2015, 3:45 PM-5:45 PM

202/204 Physics

Host: Lisa Manning

How do its editors determine which papers to publish in PRL? What guidelines would be helpful to you as an author and a referee? Why should you submit your work to us? How are journals in general and PRL in particular reorienting amid increasing challenges in the landscape of physics publications? I plan to address these and related issues, including a few changes we're implementing, during my presentation.

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Contact Information:
shdavis@syr.edu
315-443-5960

CM

### Emergence of Large-Scale Epithelial Mechanics from Cell-Scale Processes - Shaping a Fly Wing

Nov 13, 2015, 11:00 AM-1:00 PM

202/204 Physics

Host: Mark Bowick

Epithelia are two-dimensional cellular sheets. They are active visco-elastic materials which gain their mechanical properties from the collective behavior of a large number of cells. Nowadays, we are able to image tissues with up to 10 000 cells in vivo where the behavior of each individual cell can be followed in detail. We want to understand how large-scale tissue deformation and stresses emerge from the behavior of individual cells.

Here, we study this question in the developing Drosophila wing epithelium. We first establish a general geometrical framework that exactly decomposes large-scale tissue deformation into contributions by different kinds of cellular processes. These processes comprise cell shape changes, cell neighbor exchanges (T1 transitions), cell divisions, and cell extrusions (T2 transitions). As the key idea, we introduce a tiling of the cellular network into triangles. This allows us to define the precise contribution of each kind of cellular process to large-scale tissue deformation. Additionally, our rigorous approach reveals subtle effects of correlated cellular motion, which constitute a novel source of tissue deformation.

Based on this geometrical framework, we describe Drosophila wing mechanics using a novel continuum mechanical model. Similar to preceding models, we describe the wing epithelium as visco-elastic. However in addition to that, our observations led us to appreciate novel effects.

We found active cell rearrangements that are oriented on large scales and have an axis orthogonal to the shear stress axis. Furthermore, cell rearrangements did not respond immediately to material stresses, but were rather delayed. These findings are further underpinned using mechanical and genetic perturbations.

With our work, we contribute to an understanding of epithelial deformation and mechanics, linking it to cellular mechanical properties and cell-scale events.

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Contact Information:
shdavis@syr.edu
315-443-5960

HE

### Models and Signatures for Neutral Naturalness

Nov 9, 2015, 2:00 PM-4:00 PM

202 Physics

Host: Jay Hubisz, jhubisz@syr.edu, 315-443-2653

In the light of the null results in searches for top partners at the 8 TeV LHC, there recently has been an increased interest in models with color neutral top partners. I will review some aspects of neutral naturalness, and discuss some opportunities for progress on the fronts of model building, collider searches and dark matter.  (1410.6808, 1411.7393 and in progress with Matt Strassler, Nathaniel Craig, Pietro Longhi, Dean J. Robinson, Yuhsin Tsai and Marat Freytsis.)

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Contact Information:
David Schaich, Series Director
daschaich@gmail.com
315-415-3277

CM

### Echoes of the Glass Transition in Athermal Soft Spheres

Nov 6, 2015, 11:00 AM-1:00 PM

202/204 Physics

Host: Lisa Manning

The glass transition and the athermal jamming transition are both transitions from one disordered state to another marked by a sudden increase in rigidity. Before the onset of rigidity thermal hard spheres and athermal soft spheres both share the same configuration space. Is there a signature of the glass transition in the topology of the allowed configuration space and is this same signature present for athermal spheres? In this talk, I will answer this question by introducing the concept of local rigidity and demonstrate the existence of a pre-jamming phase transition precisely at the glass transition density.

http://physics.uoregon.edu/profile/peterm/

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Contact Information:
shdavis@syr.edu
315-443-5960

CM

### The Andersen-Parrinello-Rahman Method Revised into a Scale Bridging Device

Oct 28, 2015, 11:00 AM-1:00 PM

202/204 Physics

Host: Matteo Paoluzzi

**NOTE: Wednesday Seminar**

Around 35 years ago, Andersen, Parrinello and Rahman had the idea of letting the molecular-dynamics (MD) cell vary its volume (Andersen) and shape (Parrinello & Rahman) with time. The particle velocity was hence decomposed into the sum of a spatially tidy entrainment velocity, parameterized by the cell deformation rate, and a disordered streaming velocity. In order to govern the collective degrees of freedom associated with the cell, the Lagrangian functional was extended in a smart ad-hoc way. Whether the extended Lagrangian could be derived from “first principles” was a question left for further study, as Parrinello & Rahman themselves stated. In reality, since MD practitioners always considered the APR method just as an expedient trick for generating the desired particle statistics, this foundational issue remained latent until recently, when somebody with a background in continuum mechanics (CM) started looking at the APR method from an antipodal point of view. Here the idea is to bring the deforming computational cell to the fore, identifying it with an element - i.e., an infinitesimally small piece - of a continuous medium. Seen in this perspective, the appealing feature of the APR method is that it establishes a natural, explicit coupling between molecular and continuum DOFs. In conventional applications, dynamical quantities work-conjugate to these latter DOFs - namely, stress - are regarded as prescribed: as a matter of fact, Andersen’s original motivation was that of devising a barostat. In the novel multiscale implementation of the method, the stress is a priori unknown: to determine it, CM PDEs have to be solved concurrently with MD ODEs.

Roughly speaking, the solution strategy goes as follows. Imagine considering a material aggregate as either a molecular system or a continuous medium, and wishing to relate the two representations. Assume that the fields entering the continuum description, such as strain and stress, are adequately sampled on an array of positions (think of Gauss points in a finite element model), whose typical spacing H is enormously larger than the average intermolecular distance d. Associate with each of these macroscopic sampling positions an APR cell, whose reference size h is large enough with respect to d in order to allow for a decent sampling of the microscopic molecular states, and still much smaller than H: H >> h >> d (in practice, it is also essential to take full advantage of the fact that, typically, H/h >> h/d). Now, let the molecules in each cell interact directly with each other (and with their h-neighboring images), while being indirectly affected by those in the H-neighboring cells via the collective degrees of freedom of the deforming APR cell, governed by the force balance and compatibility equations of CM (sampled at the H scale). In turn, the elementwise stress-strain relation characterizing the response of the medium arises as an emergent property of MD (computed on the h scale).

Antonio DiCarlo website

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Contact Information:
shdavis@syr.edu
315-443-5960

HE

### What is a 6D SCFT?

Oct 26, 2015, 2:00 PM-4:00 PM

202 Physics

Host: Scott Watson, gswatson@syr.edu, 315-443-8280

Though long thought not to exist, arguments from string theory strongly indicate the existence of non-trivial interacting conformal field theories in six dimensions.  In this talk, I review the evidence that 6D supersymmetric conformal field theories (SCFTs) exist, and then explain how to use the geometry of extra dimensions to classify all such theories.  A surprising outcome of this work is that all of these theories admit the structure of a simple generalization of quiver (i.e. moose) diagrams used in the study of lower-dimensional quantum field theories.  Time permitting, I will also discuss what we know about these interacting fixed points, and their consequences for understanding quantum field theory in diverse dimensions.

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Contact Information:
David Schaich, Series Director
daschaich@gmail.com
315-415-3277

CM

### Polarization of Cells and Soft Objects Driven by Mechanical Interactions - Consequences for Migration and Chemotaxis

Oct 23, 2015, 11:00 AM-1:00 PM

202/204 Physics

Host: Cristina Marchetti

We study a generic model for the polarization and motility of self-propelled soft objects, biological cells, or biomimetic systems, interacting with a viscous substrate. The active forces generated by the cell on the substrate are modeled by means of oscillating force multipoles at the cell-substrate interface. Symmetry breaking and cell polarization for a range of cell sizes naturally “emerge” from long range mechanical interactions between oscillating units, mediated both by the intracellular medium and the substrate. However, the harnessing of cell polarization for motility requires substrate-mediated interactions. Motility can be optimized by adapting the oscillation frequency to the relaxation time of the system or when the substrate and cell viscosities match. Cellular noise can destroy mechanical coordination between force-generating elements within the cell, resulting in sudden changes of polarization. The persistence of the cell’s motion is found to depend on the cell size and the substrate viscosity. Within such a model, chemotactic guidance of cell motion is obtained by directionally modulating the persistence of motion, rather than by modulating the instantaneous cell velocity, in a way that resembles the run and tumble chemotaxis of bacteria.

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Contact Information:
shdavis@syr.edu
315-443-5960

C

### CUWiP Informational Session

Oct 22, 2015, 3:45 PM-5:45 PM

202/204 Physics

(refreshments 3:30pm)

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Contact Information:
shdavis@syr.edu
315-443-5960

HE

### Galilean Creation of the Inflationary Universe

Oct 16, 2015, 12:30 PM-2:30 PM

208 Physics

Host: Scott Watson, gswatson@syr.edu, 315-443-8280

It has been pointed out that the null energy condition can be violated stably in some non-canonical scalar-field theories. This allows us to consider the Galilean Genesis scenario in which the universe starts expanding from Minkowski spacetime and hence is free from the initial singularity. We use this scenario to study the early-time completion of inflation, pushing forward the recent idea of Pirtskhalava et al. We present a generic form of the Lagrangian governing the background and perturbation dynamics in the Genesis phase, the subsequent inflationary phase, and the graceful exit from inflation, as opposed to employing the effective field theory approach. Our Lagrangian belongs to a more general class of scalar-tensor theories than the Horndeski theory and Gleyzes-Langlois-Piazza-Vernizzi generalization, but still has the same number of the propagating degrees of freedom, and thus can avoid Ostrogradski instabilities. We investigate the generation and evolution of primordial perturbations in this scenario and show that one can indeed construct a stable model of inflation preceded by (generalized) Galilean Genesis.

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Contact Information:
David Schaich, Series Director
daschaich@gmail.com
315-415-3277

CM

### Microswimmer — From Swimming Bacteria to Collective Behaviours of Active Brownian Particles

Oct 16, 2015, 11:00 AM-1:00 PM

202/204 Physics

Host: Cristina Marchetti

Locomotion is a major achievement of biological evolution. Microorganisms, such as bacteria, algae, and sperm cells are equipped with flagella and are able to exploit drag for their propulsion. Two prominent swimming mechanisms are rotating helical flagella, exploited by many bacteria, and snake-like or whip-like motion of eukaryotic flagella, utilized by sperm and algae. Thereby, hydrodynamic interactions play a major role in the swimming motion.

In assemblies of motile microorganisms, cooperativity plays a major role as they exhibit highly organized movements with remarkable large-scale patterns such as networks, complex vortices, or swarms. To unravel the emergent behaviors often simplified models such as active Brownian particles (ABPs) are considered. The generic approaches provide valuable insight into the non-equilibrium statistical aspects of active matter.

In the talk, theoretical and computer simulation results will be presented for the swimming behavior of E. coli bacteria, both in bulk and at surfaces. Moreover, the cooperative dynamics of ABPs will be discussed and a link will be established to the non-equilibrium pressure equation of state.

Roland Winker's webpage

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Contact Information:
shdavis@syr.edu
315-443-5960

C

### Capillary Fracture

Oct 9, 2015, 11:00 AM-1:00 PM

202/204 Physics

Host: Cristina Marchetti

I will describe the initiation and growth of fractures in gels close to their solid-liquid transition, caused by the placement of a fluid droplet on the surface. In experiments, we observe that channel fractures form at the surface of the gel, driven by fluid propagating away from the central droplet. The fractures take the form of starburst-like cracks, with their initiation governed by two processes. First, surface-tension forces exerted by the droplet deform the gel substrate and break azimuthal symmetry. We model the substrate as an incompressible, linear-elastic solid and characterize the elastic response to provide a prediction for the number of fracture arms as a function of material properties and geometric parameters. Second, a thermally-activated process initiates a starburst-shaped collection of fractures corresponding to this strain-patterning. Once initiated, the fractures grow with a universal power law L=t^3/4, with the speed limited by the transport of an inviscid fluid into the fracture tip.

Karen Daniel's webpage

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Contact Information:
shdavis@syr.edu
315-443-5960

C

### Temperature-like Variables in Granular Materials

Oct 8, 2015, 3:45 PM-5:45 PM

202/204 Physics

Host: Jen Schwarz

(refreshments 3:30pm)

Statistical mechanics has provided a powerful tool for understanding the thermodynamics of materials. Because granular materials exhibit reproducible statistical distributions which depend in simple ways on macroscopic parameters such as volume and pressure, it is tempting to create a statistical mechanics of athermal materials. I will describe a suite of experiments on two-dimensional granular materials which investigate to what extent these ideas are meaningful. For example, under agitated conditions, we measure both bulk and particle-scale dynamics, and find a number of thermal-like behaviors including diffusive dynamics, a granular Boyle's Law with a van der Waals-like equation of state, and energy equipartition for rotational and translational degrees of freedom. However, the scarcity of free volume within a granular material provides a crucial control on the dynamics, and each of the above thermal-like behaviors is accompanied by interesting caveats. In an apparatus designed to generate a large number of static configurations, we test whether or not various temperature-like variables are able to equilibrate between a subsystem and a bath. We find that while a volume-based temperature known as "compactivity" fails to equilibrate, a stress-based temperature succeeds. This points to the importance of interparticle forces in controlling the mechanics of granular materials.

Karen Daniel's webpage

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Contact Information:
shdavis@syr.edu
315-443-5960

HE

### Walking and Conformal Dynamics in Many-Flavor QCD on the Lattice

Oct 5, 2015, 2:00 PM-4:00 PM

202 Physics

Host: Simon Catterall, smc@physics.syr.edu, 315-443-5978

In the search for a realistic walking technicolor model, QCD with many flavors, in particular with Nf=8, is an attractive candidate, which has been found to have a composite scalar as light as pion.  Based on lattice simulations with the HISQ action, I will present our lattice results of the scaling properties of various hadron spectra, including the (pseudo)scalar, vector, and baryon channels in comparison with Nf=12 QCD, which is most likely in the conformal phase.  Some implications for dark matter and collider phenomenology in the technicolor model will be also discussed.

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Contact Information:
David Schaich, Series Director
daschaich@gmail.com
315-415-3277

CM

### The Geometry and Mechanics of Growth and Defects

Oct 2, 2015, 11:00 AM-1:00 PM

202/204 Physics

Host: Mark Bowick

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Contact Information:
shdavis@syr.edu
315-443-5960

C

### Hard Problems in Soft Matter - How We Think, Eat, and Protect Ourselves

Oct 1, 2015, 3:45 PM-5:45 PM

202/204 Physics

(refreshments 3:30pm)

Soft matter is the study of matter that easily deforms via thermal fluctuations and/or external and/or internal driving. Given this rather inclusive definition, a vast range of systems falls under the soft matter purview, including brain tissue, cell membranes, biopolymers, and granular materials. I will address (1) how the brain gets its folds to ultimately better understand the interplay between structure and function of the brain, (2) how cells engulf extracellular proteins, i.e. how we eat, with "we" in the collective sense of living systems, and (3) how we (cells and humans) build disordered frameworks with structural integrity (rigidity) to protect ourselves from the "elements".

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Contact Information:
shdavis@syr.edu
315-443-5960

CM

### ***BMCE Seminar***

Sep 25, 2015, 1:00 PM-3:00 PM

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Contact Information:
shdavis@syr.edu
315-443-5960

C

### Leveraging Computational Social Science to Address Grand Societal Challenges

Sep 24, 2015, 9:00 AM-11:00 AM

Strasser Room (220 Eggers Hall)

Kameshwar C. Wali Lecture in the Sciences and Humanities

The increased access to big data about social phenomena in general, and network data in particular, has been a windfall for social scientists. But these exciting opportunities must be accompanied with careful reflection on how big data can motivate new theories and methods. Using examples of his research in the area of networks, Contractor will argue that Computational Social Science serves as the foundation to unleash the intellectual insights locked in big data. More importantly, he will illustrate how these insights offer social scientists in general, and social network scholars in particular, an unprecedented opportunity to engage more actively in monitoring, anticipating and designing interventions to address grand societal challenges.

http://nosh.northwestern.edu

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Contact Information:
shdavis@syr.edu
315-443-5960

C

### The Big Science of Little Neutrinos

Sep 22, 2015, 3:45 PM-5:45 PM

202/204 Physics

(refreshments 3:30pm)

Experimental studies of neutrinos are notoriously challenging due to the feebleness of their interactions with matter, so it may seem counterintuitive to suggest these “little neutral ones” could have played a central role in the development of our universe to its current matter-dominated state. This talk will provide an overview of the interesting physics questions associated with neutrinos, and will give an outlook on the global program to build bigger and better detectors to uncover the answers to these questions.

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Contact Information:
shdavis@syr.edu
315-443-5960

CM

### ***BMCE Seminar***

Sep 18, 2015, 1:00 PM-3:00 PM

Jayaraman Homepage

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Contact Information:
shdavis@syr.edu
315-443-5960

C

### Mechanical Quantum Systems

Sep 17, 2015, 3:45 PM-5:45 PM

202/204 Physics

(refreshments 3:30pm)

The field of mechanical quantum systems has made great strides in recent years developing the technology to begin eliciting and studying quantum behavior of structures that are normally well described by classical laws of physics. While the full potential of the field is yet unknown, it is thought that these mechanical systems could have important applications serving as elements in quantum computing and communication architectures, and could also enable explorations of fundamental topics in quantum mechanics like the quantum-to-classical divide. In my talk, I will first give an overview of this growing field. Then I will highlight ongoing work in my group to develop a particular type of mechanical quantum system - a quantum electromechanical system - that is composed of integrated superconducting circuity and nanomechanical elements and could prove to be an important test-bed for the study of quantum mechanics in new macroscopic limits.

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Contact Information:
shdavis@syr.edu
315-443-5960

C

### Catching Gravitational Waves

Sep 10, 2015, 3:45 PM-5:45 PM

202/204 Physics

(refreshments 3:30pm)

In 1916 Einstein first predicted the existence of gravitational waves. But due to their intrinsic weakness it took almost a century of technological progress to build a receiver capable of detecting gravitational waves. This receiver, a set of laser interferometers with 4km arm length able to detect distance variations as small as one 100'000th the size of an atomic nucleus, is the Advanced Laser Interferometer Gravitational-wave Observatory. It will start its first observation run this fall. Advanced LIGO is designed to observe gravitational waves from the merger of binary neutron stars and black holes, providing the first direct measurements of strong field gravity. I will discuss the current status and sensitivity of the Advanced LIGO detectors, and I will explore options for short and long term upgrades. In particular, I will focus on the two most limiting noise sources: quantum noise of the light and thermal noise, highlighting some of the work done in my group. For lowering the quantum noise, the use of non-classical light looks most promising, and we are focusing on integrating this technology to Advanced LIGO. For mitigating thermal noise several approaches are possible. The most far reaching one will lead us into the design of future gravitational wave detectors, capable of observing mergers of binary neutron stars at red shifts above z=7.

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Contact Information:
shdavis@syr.edu
315-443-5960

CM

### ***BMCE Seminar***

Sep 4, 2015, 1:00 PM-3:00 PM

Velev Group

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Contact Information:
shdavis@syr.edu
315-443-5960

C

### The State of the Universe

Sep 3, 2015, 3:45 PM-5:45 PM

Room 202/204 Physics

(refreshments 3:30pm)

Cosmological observations provide overwhelming evidence that our universe is almost entirely comprised of dark energy and dark matter, both of which have no theoretical explanation within the standard model of particle physics. The former is responsible for a current period of cosmic acceleration, much like that which occurred in the earliest moments of the universe. The early period of cosmic acceleration, known as inflation, was vital in providing the primordial seeds from which galaxies and clusters formed, whereas the late time acceleration could eventually lead to the vanishing of most structure in the universe. The driving force behind cosmic acceleration, as well as dark matter, still remains elusive from the point of view of a microscopic theory. Combined with fundamental questions, such as the origin of particle mass and how electroweak symmetry is broken, these conundrums require physics beyond the standard model. In this talk I will review both the theoretical and observational status of these issues with an emphasis on the excitement surrounding current and upcoming experiments.

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Contact Information:
shdavis@syr.edu
315-443-5960

C

### Department Welcome Reception (Tuesday)

Sep 1, 2015, 3:45 PM-5:45 PM

Room 202/204 Physics

Hosted by the Physics Department

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Contact Information:
shdavis@syr.edu
315-443-5960

TD

### Thesis Defense - Measurement of the Form Factor Shape for the Semileptonic Decay Lb → LcMuNu

Aug 27, 2015, 3:30 PM-5:30 PM

Room 202 Physics

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Contact Information:
shdavis@syr.edu
315-443-5960

TD

### Thesis Defense - The Effects of Spinning Neutron Stars and Hlack Holes on Gravitational-Wave Searches for Binary Neutron Star and Neutron Star - Black Hole Mergers

Aug 20, 2015, 2:00 PM-4:00 PM

Room 208 Physics

TD

### Thesis Defense - Modulation of Charged Biomimetic Membrane by Bivalent Ions

Aug 17, 2015, 3:00 PM-5:00 PM

Room 202 Physics

TD

### Thesis Defense - Beyond Standard Model Physics Under the Ground and in the Sky

Jul 15, 2015, 11:00 AM-1:00 PM

Room 202 Physics

TD

### Thesis Defense - Collective Phenomena in Active Systems

Jul 14, 2015, 10:00 AM-12:00 PM

Room 202 Physics

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Contact Information:
shdavis@syr.edu
315-443-5960

C

### How do Molecules Form in Star-forming Regions?

Jul 13, 2015, 3:00 PM-5:00 PM

208 Physics

Host: Gianfranco Vidali

More than 150 different gas phase molecules and around 20 molecular species on the grain surface have been detected in various regions of the Interstellar Medium (ISM). Many of these molecules are organic, and therefore important astro-biologically. These molecules range in complexity from diatomic H2 to a 15-atom linear nitrile, HC13N. I will discuss how these molecules are formed in a variety of astrophysical sources, with an emphasis on their formation in the star forming regions.

Numerical techniques we developed to study the formation of these molecules include the rate equation method, as well as several more detailed stochastic methods, based upon either the direct solution of the master equation or a Monte Carlo realization of the problem. In this talk, I will present results obtained for diffuse clouds and dust grain mantle compositions, and will discuss their dependence on various physical parameters associated with a star forming region.

CM

### Phase Transitions and Pattern Formation in Myxococcus Xanthus

Jun 5, 2015, 11:00 AM-1:00 PM

202/204 Physics

Host: Cristina Marchetti