## UO Center for High Energy Physics

January 11, 2012 (Wednesday) Tom Schwarz, Fermilab SEMINAR CANCELLED

February 10, 2012 (Friday) Stephanie Majewski, Brookhaven National Laboratory

February 17, 2012 (Friday) Corrinne Mills, Harvard University

February 22, 2012 (Wednesday) Eric Thrane, University of Minnesota

February 27, 2012 (Monday) Bijan Berenji, SLAC

February 29, 2012 (Wednesday) Peter Onyisi, University of Chicago

March 5, 2012 (Monday) Dipongkar Talukder, Washington State University

March 7, 2012 (Wednesday) Jahred Adelman, Yale University

March 9, 2012 (Friday) Toyoko Orimoto, CERN

## Search for Low Mass Dark Matter

Tom will talk on a novel direct detection experiment at Fermilab and a collider-based search, both aimed at low mass dark matter.

Noon, 472 Willamette Hall

## Supersymmetry Searches at ATLAS

I will present the results of searches for Supersymmetry at ATLAS using 1-2 fb^{-1} of sqrt(s) = 7 TeV data from the LHC, focusing on the all-hadronic signature of jets + missing transverse momentum. Stringent limits are set on squark and gluino production. However, "natural" SUSY suggests that third-generation squarks may be within reach. Recent results and an outlook for dedicated stop and sbottom searches will be discussed.

4:00pm, 472 Willamette Hall

Refreshments served at 3:45

## Testing QCD with the ATLAS Inclusive W Data

In 2010, ATLAS collected over 100,000 W events each in the electron + neutrino and muon + neutrino final states. These events have been the raw material for a rich exploration of QCD dynamics in high energy hadron collisions. I will review the measurements done with the inclusive W (and Z) samples, focusing on the W charge asymmetry and the W transverse momentum measurements and their connection with the broader ATLAS physics program.

4:00pm, 472 Willamette Hall

Refreshments served at 3:45

## From Gamma-ray Bursts to the Big Bang: Cosmology and Astrophysics with LIGO

Gravitational-wave signals are often classified by their duration. For example, coalescing binary systems produce a short "chirp" whereas isolated neutron stars emit a signal, which persists over the course of the observing period (typically years). I describe the interesting physics revealed by looking at gravitational waves at different time scales. For example, transient signals can be used to observe the first moments in the life of a newborn neutron star. Persistent stochastic signals, on the other hand, can tell us about the distribution of neutron star binaries as well as the period of inflation immediately following the Big Bang. I describe recent and future work aimed at exploring these different regimes and how they provide complementary insights into astrophysics and cosmology.

4:00pm, 472 Willamette Hall

Refreshments served at 3:45

## Limits on Large Extra Dimensions in the ADD Model with Fermi-LAT and Fermi-LAT Science Highlights

On behalf of the Fermi-LAT collaboration, I present limits for the compactification scale in the theory of Large Extra Dimensions (LED) of Arkani-Hamed, Dimopou-los, and Dvali, as published in JCAP in 2012 (arXiv:1201.2460).

We use 11-months of Fermi-LAT data to set gamma-ray flux limits for 6 gamma-ray faint neutron stars (NS). To set limits on LED, we use the model of Hannestad and Raffelt (HR) that calculates the Kaluza-Klein graviton (GKK) production in supernova cores and the large fraction subsequently gravitationally bound around the resulting NS. The decays $G_{KK} --> \gamma\gamma$ should contribute to the flux from NSs. For n = 2,3,..7 LED of the same size in the context of the HR model, we use MC techniques to calculate the expected differential flux of gamma- rays arising from these KK gravitons, including the effects of the age of the NS, graviton orbit, and absorption of gamma-rays in the mag-netosphere of the NS. We compare our MC differential flux to the experimental differential flux using maximum likelihood techniques, and obtain limits on LED that are more restrictive than past EGRET-based optimistic limits that do not include these important corrections. Additionally, our limits are more stringent than collider limits for 3 or fewer LED. If the effective Planck scale is around a TeV, then with n = 2,3, we conclude the LED topology is non-toroidal.

In addition, I discuss highlights of science with Fermi-LAT and dark matter studies.

4:00pm, 472 Willamette Hall

Refreshments served at 3:45

## Looking for the Higgs in WW Decays at ATLAS

The electroweak symmetry breaking mechanism must produce new particles or interactions that couple to pairs of weak bosons. In the minimal Standard Model, this role is held by the Higgs boson, which consequently frequently decays to WW. I will describe the ATLAS search for the SM Higgs in the H -> WW -> lnulnu decay channel.

4:00pm, 472 Willamette Hall

Refreshments served at 3:45

## Multi-baseline Searches for Stochastic Sources and Black Hole Ringdown Signals in LIGO-VIRGO Data

We present a framework for the detection of stochastic gravitational-wave (GW) backgrounds, from cosmological and astrophysical sources, using radiometry with a network of gravitational-wave interferometers. The search statistic itself is derived from the likelihood ratio of the cross-correlation of the data across all possible baselines in a detector network, and reveals invaluable knowledge about the coherent performance of the GW detector network. We discuss how the neutron stars in the Virgo Cluster are modeled and the use of radiometry to search for their stochastic GW signature in LIGO-VIRGO data. We also discuss a template-based multi-detector coherent search for perturbed black hole ringdown signals. Like the past "coincidence" ringdown searches in LIGO data, our method incorporates knowledge of the ringdown waveform in constructing the search templates. Additionally, it checks for consistency of signal amplitudes and phases in the different detectors with their different orientations and with the signal arrival times in them. In this talk I will detail the advantages of implementing the coherent constructs in the search pipeline.

4:00pm, 412 Willamette Hall

Refreshments served at 3:45

## New Physics Searches with Multiple Charged leptons at ATLAS

4:00pm, 472 Willamette Hall

Refreshments served at 3:45

## The Search for the Higgs in the Diphoton Channel with the CMS Detector

The Higgs boson is the last missing piece of the Standard Model of particle physics. As such, the discovery of the Higgs boson is one of the primary goals of the Compact Muon Solenoid Experiment, a general purpose particle detector experiment at the Large Hadron Collider at CERN. Instrumented with a high-precision, high-granularity electromagnetic crystal calorimeter, CMS has been optimized for the discovery of the Higgs in the "golden" two photon decay channel. I present an overview of the Standard Model, as well as the motivation for finding the Higgs boson. I will also describe the CMS detector, focusing on the strengths of the electromagnetic calorimeter, which is crucial for searches with photon final states. Then, I will describe the latest results in the search for the Higgs in the two photon channel, as well as the prospects with 2012 data.

4:00pm, 472 Willamette Hall

Refreshments served at 3:45