Elementary Particle Physics Seminar

semester, 2015


Tuesday, January 20th 2015
There will be no seminar this week.

Tuesday, January 27th 2015
There will be no seminar this week.

Tuesday, February 3rd 2015
There will be no seminar this week.

Tuesday, February 10th 2015
To be announced.

Tuesday, February 17th 2015
To be announced.

Tuesday, February 24th 2015
To be announced.

Tuesday, March 3rd 2015
To be announced.

Tuesday, March 10th 2015
To be announced.

Tuesday, March 17th 2015
1:25 pm:
Speaker: John Ellis, CERN
Subject: Future circular colliders
Faculty Host: Keith Olive

Tuesday, March 24th 2015
To be announced.

Tuesday, March 31st 2015
To be announced.

Tuesday, April 7th 2015
To be announced.

Tuesday, April 14th 2015
To be announced.

Tuesday, April 28th 2015
There will be no seminar this week.

Tuesday, May 5th 2015
There will be no seminar this week.

Wednesday, May 20th 2015
1:00 pm:
Speaker: Alex Gude
Subject: Measurement of the phistar distribution of Z bosons decaying to electron pairs with the CMS experiment at a center-of-mass energy of 8 TeV

Measurements of the Z boson transverse momentum (QT) spectrum serves as
both a precision test of non-perturbative QCD and helps to reduce the
uncertainty in the measurement of the W boson mass. However, QT is
limited at its lowest values by detector resolution, and so a new variable,
Phi*, which performs better in the low QT region, is used instead.
This thesis presents the first measurement the normalized differential cross
section of Z bosons decaying to electron pairs in terms of Phi* at
sqrt(s) = 8 TeV. The data used in this measurement were collected by the CMS
detector at the LHC in 2012 and totaled 19.7/fb of integrated
luminosity. The results are compared to predictions from simulation, which are
found to provide a poor description of the data.


Tuesday, July 21st 2015
Speaker: Kelly Stifter, University of Minnesota
Subject: The new Beam Halo Monitor system for the CMS experiment at the LHC

A new Beam Halo Monitor (BHM) detector system has been installed in the CMS cavern to measure the machine-induced background (MIB) from the LHC. This background originates from interactions of the LHC beam halo with the final set of collimators before the CMS experiment and from beam gas interactions. The BHM detector uses the directional nature of Cherenkov radiation and event timing to select particles coming from the direction of the beam and to suppress those originating from the interaction point. It consists of 40 quartz rods, placed on each side of the CMS detector, coupled to UV sensitive PMTs. For each bunch crossing, the PMT signal is digitized by a charge integrating ASIC and the arrival time of the signal is recorded. The data are processed in real time to yield a precise measurement of per-bunch-crossing background rate for each beam. This measurement is made available to CMS and the LHC, in order to provide real-time feedback on the beam quality and improve the efficiency of data taking. The BHM detector is now in the commissioning phase. An overview of the system and first results from Run II will be presented.


Wednesday, August 12th 2015
Speaker: Jianming Bian and Greg Pawloski, University of Minnesota
Subject: First Results from the NOvA Experiment
Light refreshments will be served in the PAN lobby after the seminar

NOvA, the world’s leading long-baseline neutrino-oscillation experiment, uses a beam originating at the Fermi National Accelerator Laboratory near Chicago to measure electron-neutrino appearance and muon-neutrino disappearance with a 14,000-ton detector in northern Minnesota. Understanding neutrinos is one of the most important goals of elementary particle physics and could lead to deeper understanding of the origin and evolution of the universe. University of Minnesota faculty, staff and students have played leading roles in the design and construction of the NOvA laboratory and detector, as well as in the analysis of data collected during the first year and a half of operation. This special seminar will present first results from NOvA’s electron- and muon-neutrino measurements, along with an overall introduction to the NOvA project and a discussion of future running plans and ultimate scientific reach.


Wednesday, September 9th 2015
Speaker: Marvin Marshak, University of Minnesota
Subject: The Deep Underground Neutrino Experiment (DUNE)

Wednesday, September 16th 2015
There will be no seminar this week.

Wednesday, September 23rd 2015
Speaker: Dan Ambrose, University of Minnesota
Subject: The µ2e Experiment

Wednesday, September 30th 2015
Speaker: Juliette Alimena, Brown University
Subject: Search for Stopped Particles from Decays to Delayed Muons
Note the change from the usual time, this week only

Massive, long-lived particles do not exist in the SM, and so any sign of them would be an 3 indication of new physics. There are many BSM theories that predict long-lived particles, including split SUSY, hidden valley scenarios, GUT theories, and various SUSY models. Long-lived particles could be sufficiently massive that they would loose sufficient energy through ionization or hadronization, depending on the type of particle, that they would come to rest inside the detector material. A search for long-lived particles that stop in the CMS detector and decay to muons was performed. The decays of the stopped particles could be observed when there are no pp collisions in the detector, namely during gaps between bunch crossings. The analysis uses 19.7 1/fb of 8 TeV data collected by CMS in 2012, during a search interval of 293 hours of trigger livetime. We also set cross section limits for each mchamp mass as a function of lifetime, for lifetimes between 100 ns and 10 days. These are the first limits for stopped particles that decay to muons, and they are also the first limits for lepton-like multiply charged particles that stop in the detector.


Wednesday, October 7th 2015
Speaker: Matt Strait, University of Chicago
Subject: Cosmogenic isotope production by muon capture in Double Chooz

Wednesday, October 14th 2015
Speaker: Jianming Bian, University of Minnesota
Subject: Exotic quark states at BESIII

In the quark model, hadrons are dominantly bound states of quark-antiquark pairs (mesons) or three quarks (baryons), but QCD also allows for hadronic states composed of more quarks bound together. Recently, BESIII, Belle and LHCb have confirmed the existence of four-quark and pentaquark candidates. These new states, along with experimentally observed resonances that do not fit well into the charmonium and bottomonium spectra, present challenges and opportunities for strong interaction theory. In this talk, I will review results on these exotic quark states that have been obtained by the BESIII experiment at the Beijing Electron Positron Collider II (BEPCII).


Wednesday, October 21st 2015
There will be no seminar this week.

Wednesday, October 28th 2015
Speaker: Debarati Roy, Saha Institute of Nuclear Physics, Kolkata, India
Subject: Reconstructing Events with Jets at the LHC

Jets are very important tool in studying physics at a hadron collider like the LHC. They are the direct manifestations of quarks and gluons and they constitute the most essential tool to test QCD. In this seminar I will talk about the reconstruction of jets in the LHC. It involves combining the information from several detectors. It also includes the best possible calibration of the detector elements, jet energy correction from information of collision data as well as Monte Carlo, correcting from the effect of pile up events etc. Reconstructed jets are then utilized in computing several variables used in understanding perturbative as well as non-perturbative QCD effects, and also as efficient tools in search of new physics. Some of the tests of the Standard Model will be discussed.


Wednesday, November 4th 2015
There will be no seminar this week.

Wednesday, November 11th 2015
There will be no seminar this week.

Wednesday, November 18th 2015
Speaker: Marianna Gabrielyan, University of Minnesota
Subject: Search for exotic contributions to $\nu_\mu \to \nu_e$ transitions with MINOS and MINOS+

The observed neutrino flavor transitions are currently explained by the three flavor neutrino oscillation phenomenon, considered to be the leading order mechanism behind the flavor transitions. Currently existing data from LSND, miniBooNE and reactor experiments demonstrate anomalies that could potentially be indications of non-standard neutrino phenomena. MINOS can probe transitions from muon neutrinos to electron neutrinos and search for anomalous behavior that cannot be explained by standard model neutrino oscillations. I will present the search for second order effects in the flavor transitions by analyzing the MINOS
νμ→νe- channel.


Wednesday, November 25th 2015
There will be no seminar this week.

Wednesday, December 2nd 2015
Speaker: Rik Gran, University of Minnesota, Duluth
Subject: Multi-nucleon effects in neutrino-carbon interactions -- results from the MINERvA experiment.

Current and future neutrino oscillation experiments will depend on accurate neutrino interaction models in order to measure oscillation parameters and explore for CP violation. To support this, recently updated models for neutrino-nucleus interactions are compared to new cross sections measured by the MINERvA experiment. These results cover low momentum transfer events from quasi-elastic to resonance production, which are the most important for oscillation measurements. Discussion will include the impact on oscillation experiments and also the neutrino view of these multi-nucleon effects.


Wednesday, December 16th 2015
To be announced.

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