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Center for
Neutrino Physics
Center for Neutrino Physics Seminars
Fall 2015 - Spring 2016
[ Aug | Sept | Oct | Nov | Dec | Jan | Feb | Mar | Apr | May ]

Coordinators: Lara Andreson, Shunsaku Horiuchi

2014-2015

2016-2017
August 2015
Aug 26 (Wed)
4:00pm - 5:00pm
304 Robeson

(Poster)
Nick Ryder (University of Oxford)

The SoLid Experiment

The SoLid collaboration aim to solve the reactor neutrino anomaly by 2020. We will determine whether the anomaly is due to oscillations to a new type of `sterile' neutrino by measuring the anti-neutrino flux between 5.5 and 10 m from a nuclear reactor core. By measuring the flux as a function of energy and distance a direct search for oscillations can be performed without relying on flux calculations. I will explain the reactor anomaly and other motivations for our experiment from unexpected structure in the reactor flux spectrum and nuclear safeguards. Performing a neutrino experiment so close to a reactor core presents a number of challenges. I will explain these challenges and the novel, highly segmented, composite scintillator anti-neutrino detector we have developed to overcome them. I will discuss the prototype detectors that we have built and our plans for a phased deployment of our full scale detector starting next year that will allow us to perform a highly sensitive search for oscillations by 2020.

Host: Jon Link
September 2015
Sept 2 (Wed)
4:00pm - 5:00pm
304 Robeson

(Poster)
Oscar Macias (Virginia Tech)

Searching for Dark Matter Self-annihilations in the Galactic Center

One of the best motivated candidates for dark matter (DM) is a weakly interacting massive particle (WIMP). This allows the DM to be a thermal relic of the big bang and the weak-scale interaction strength leads to the observed dark matter abundance. WIMPs may also self-annihilate to produce Standard Model particles with weak scale energies that, by a process of pion-0 decay, bremsstrahlung emission and inverse Compton scattering, can lead to detectable gamma-ray emission. This residual gamma-ray emission is being searched for with the Fermi Large Area Telescope (LAT), the HESS telescope and other instruments. Regions such as Dwarf Spheroidal galaxies, galaxy clusters and the Galactic Center are some of the most promising targets. Interestingly, several research teams (including the Fermi-LAT collaboration) have found an excess of extended gamma-ray emission above the background in the Galactic Center (GC) region. In this talk I will show that both, WIMPs with masses of ~10-60 GeV or a population of about 10^3 unresolved millisecond pulsars are well motivated possible explanations. Additionally, I will demonstrate that other alternative hypotheses available in the literature like Cosmic Rays interacting with molecular clouds and proton flares from the supermassive black hole Sgr A* are not able to account for both the spatial morphology and energy spectrum of the GC gamma-ray excess.

Host: Shunsaku Horiuchi
Sept 10 (Th)
2:00pm - 3:00pm
304 Robeson

(Poster)
Denis Klevers (CERN)

General U(1)×U(1) F-theory Compactifications and Beyond: Geometry of unHiggsings and novel Matter Structure

This talk is based on the paper arXiv:1507.05954 with Cvetic, Piragua and Taylor on the general construction of global F-theory compactifications with two U(1) symmetries and their "unHiggsings" to minimal non-Abelian gauge groups at special points in their moduli space. I will discuss this new construction, which produces the general Weierstrass model of an elliptic fibration with two U(1)'s. Using the full resolution of the elliptic fibration, we obtain diverse anomaly-free matter spectra, many of which not realized in earlier F-theory constructions with U(1)×U(1) gauge symmetry. It will be demonstrated that the generic U(1)×U(1) models unHiggs to theories with gauge group SU(2)×SU(2)×SU(3), SU(2)^3×SU(3), or a subgroup thereof. The resulting non-Abelian Weierstrass model exhibits a new algebraic description of the singularities in the fibration that result in the first construction of matter in the symmetric representation of SU(3). I will briefly discuss generalizations to U(1)^k factors with k > 2, which can be studied by Higgsing theories with larger non-Abelian gauge groups. This illuminates the global structure of the F-theory moduli space.

Host: Lara Anderson
Sept 16 (Wed)
4:00pm - 5:00pm
304 Robeson


Host:
Sept 23 (Wed)
4:00pm - 5:00pm
304 Robeson

Host:
Sept 30 (Wed)
4:00pm - 4:30pm
304 Robeson

(Poster)
(Presentation)
Evan O'Connor (NCSU)

Core-Collapse Supernova Neutrinos and Explosions!

Core-collapse supernovae are some of the optically-brightest astrophysical phenomena in the modern universe. This is impressive, especially given that most of the energy released is not photons, but in neutrinos. The ultimate source of energy for core-collapse supernovae is gravity. It is released when the iron core of a massive stars becomes gravitationally unstable to collapse and transitions to a neutron star. A small fraction of the released energy goes into unbinding the rest of the star and spreading the products of stellar evolution throughout the galaxy, the rest is radiated in neutrinos. The crucial machinery of the core-collapse supernova central engine that works to transition the stellar implosion into an explosion are unclear, but are the subject of intense research. Since neutrinos carry away so much energy, their role cannot be ignored, in fact they likely play very important part in the development of the explosion.

In this talk, in addition to providing a background on supernovae, supernova simulations, and the neutrino signal we expect from the next galactic event, I will present new multidimensional simulations of core-collapse supernovae performed with the FLASH hydrodynamics code and a recently implement neutrino transport scheme. I will emphasize the importance of including a general relativistic treatment of gravity.

Host: Shunsaku Horiuchi
October 2015
October 7 (Wed)
4:00pm - 5:00pm
304 Robeson

(Poster)
Andreas Kapfer (Max Planck Institute for Physics)

The Arithmetic of Elliptic Fibrations in F-theory

The geometry of elliptic fibrations translates to the physics of gauge theories when using them as part of an F-theory background. We systematically develop the dictionary between arithmetic structures on desingularized elliptic fibrations and symmetries of F-theory effective field theory. In particular we investigate the Mordell-Weil group of rational sections, and use new insights in order to define a group structure for multisections in geometries without section. Finally, by unHiggsing a U(1) theory to a non-Abelian gauge theory we define a group structure for blow-up divisors tracking the fate of the Mordell-Weil group.

Host: Lara Anderson
October 14 (Wed)
4:00pm - 5:00pm
304 Robeson

(Poster)
Kendall Mahn (Michigan State University)

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.

Host: Camillo Mariani
October 21 (Wed)
4:00pm - 5:00pm
304 Robeson

(Poster)
Kimiko Yamashita (Ochanomizu University)

Ratchet Baryogenesis during reheating

We propose a new baryogenesis scenario, which occurs during reheating after inflation. During reheating, the oscillation of the inflaton field breaks thermal equilibrium, providing one of the necessary conditions for baryogenesis. The inflaton field is assumed to couple to a complex scalar field which carries baryon number, whose self coupling breaks B and the interaction with the inflaton violates C and CP, providing the remaining two conditions for baryogenesis. The dynamics of our scenario utilizes the so-called "ratchet mechanism" found in models of biological molecular motors. There, the driving force of the ratchet movement (of molecular motors) usually comes from the oscillatory change of temperature in the non-equilibrium state. In the present scenario this driving force is provided by the oscillation of the inflaton field. Baryon number is generated by the phase of the complex scalar field being driven in a preferred direction due to the oscillatory energy provided by the inflaton and the “ratchet” which is realized by the self-coupling potential and the interaction which leads to spatial asymmetry of the dynamics. We argue that for the inflaton potential supported by recent Planck results, this scenario allows for the generation of a baryon-to-photon ratio compatible with observations.

Host: Tastu Takeuchi
October 28 (Wed)
1:00pm - 2:00pm
304 Robeson

(Poster)
Special Time
Patrick Jaffke (Virginia Tech)

Corrections to and Applications of the Reactor Antineutrino Spectrum

I will present two important corrections to the reactor antineutrino spectrum: the spent nuclear fuel (SNF) correction and the nonlinear (NL) correction. The origins and properties of these corrections are determined with analytical and computational techniques. Analyses of these corrections have shown that both are comparative with other low-energy effects. The importance of these corrections is discussed in relation to the reactor antineutrino anomaly and precision neutrino oscillation experiments.

The second half of the talk will focus on recent developments in applied antineutrino physics, specifically reactor safeguards. A historical sandbox example, the North Korean nuclear crisis, is explored where the feasibility and advantages of antineutrino safeguards are determined. Similar methods are then applied to a current scenario, testing safeguards for heavy water reactors.

Host: Patrick Huber
October 28 (Wed)
4:00pm - 5:00pm
304 Robeson

(Poster)
Artur Ankowski (Virginia Tech)

Influence of detector effects on neutrino energy reconstruction

To be able to achieve their physics goals, future neutrino-oscillation experiments will need to reconstruct the neutrino energy with very high accuracy. In this talk, based on recent papers arXiv:1507.08560 and arXiv:1507.08561, I will analyze how the energy reconstruction may be affected by realistic detection capabilities, such as energy resolutions, efficiencies, and thresholds.

Considering disappearance experiments, I will argue that for the calorimetric method of energy reconstruction, the detector performance has to be estimated with a ~10% accuracy, in order to avoid a significant bias in the extracted oscillation parameters. On the other hand, for the kinematic energy reconstruction, the oscillation results exhibit less sensitivity to an overestimation of the detector capabilities.

For an appearance experiment of a setup similar to that of the Deep Underground Neutrino Experiment, the role of the missing energy---carried out by undetected particles---turns out to have a sizable effect on calorimetric energy reconstruction. The obtained results suggest that an accurate determination of the CP violation requires the missing energy to be quantified with an accuracy exceeding 20%.

Host: Camillo Mariani
November 2015
November 4 (Wed)
4:00pm - 5:00pm
304 Robeson

(Poster)
Jahred Adelman (Northern Illinois University)

BSM Higgs searches at ATLAS

Several years after its discovery, the Higgs boson is rapidly become a key tool in the search for beyond-Standard Model physics. The talk will motivate using the Higgs sector to expand the Standard Model, and will show a selection of analyses searching for BSM physics in the Higgs sector with the ATLAS detector. Specific analyses that will be covered include searches for anomalous pair production of Higgs bosons, as well as attempts to find additional, new Higgs bosons.

Host: Shunsaku Horiuchi
November 11 (Wed)
4:00pm - 5:00pm
304 Robeson

(Poster)
(Presentation)
Szymon Manecki (Queens University)

SNO+ The Next Generation Facility for a Neutrinoless Double Beta Decay and Solar Neutrino Physics

SNO+ will be a successor of the Sudbury Neutrino Observatory (SNO) with the heavy water replaced by 780 tonnes of an organic liquid scintillator. In the first phase of the experiment, a competitive sensitivity to neutrinoless double beta decay will be achieved by loading the scintillator with tellurium-130. In addition, thanks to its deep underground location, SNO+ will have a unique potential to probe the lowest energies of the solar neutrino spectrum, and accomplish a first detection of the CNO neutrinos. The experiment will also make important measurements of geo-neutrinos and anti-neutrinos, and have excellent sensitivity to supernova neutrinos during both the double beta decay and solar neutrino stages of data taking.

In this seminar, I will present how the original SNO experiment has been converted into a next generation double beta decay and solar neutrino facility. I will specifically focus on describing the liquid scintillator and isotope loading and purification techniques. I will then emphasize how these techniques, combined with other background mitigation and reduction strategies, position SNO+ to make leading contributions in all areas of its proposed physics program.

Host: Camillo Mariani
November 18 (Wed)
4:00pm - 5:00pm
304 Robeson

(Poster)
Eric Carlson (University of California, Santa Cruz)

Confronting the Fermi Galactic Center Excess with 3D Models of the Gamma-Ray Sky

Physical models of diffuse Galactic gamma-ray emission have so-far assumed that the injection and propagation of cosmic rays in the Galaxy may be treated as axisymmetric, with cosmic-ray sources tracing the observed distributions of OB stars, pulsars, or supernova remnants; all of which underestimate the cosmic-ray population at the Galactic center. In this seminar I will move beyond these assumptions and introduce three novel model elements: fully 3D cosmic-ray propagation, 3D gas maps, and 3D cosmic-ray injection tracing the distribution of supernovae-harboring H2 regions in the Galaxy. I will show that a physically well-motivated fraction f_H2~20% of cosmic-ray sources tracing H2 (i) globally improves the quality of the fit to the observed diffuse gamma-ray emission, and (ii) highly suppresses residual gamma-ray emission from the Galactic center region. I will then discuss in detail, the impact of these changes on the Fermi Galactic Center GeV excess as well as briefly outlining future avenues for 3D diffuse gamma-ray emission modelling.

Host: Shunsaku Horiuchi
November 25 (Wed)
4:00pm - 5:00pm
304 Robeson
THANKSGIVING BREAK

December 2015
December 2 (Wed)
4:00pm - 5:00pm
304 Robeson

(Poster)
(Presentation)
Ryan Patterson (Caltech)

First neutrino oscillation results from NOvA

Non-zero neutrino mass brings with it new complexity in the neutrino sector, and major questions surrounding neutrino masses and mixing remain unanswered. Among the unknowns are the ordering of the neutrino masses, the presence (or absence) of complex phases in the PMNS matrix, and key details of flavor mixing. NOvA, a long-baseline neutrino oscillation experiment sited along Fermilab's NuMI neutrino beam, will address these questions and much more. NOvA began full operations with its 14-kton Far Detector in Ash River, Minnesota, last year and will continue through this decade. After a brief review of the physics context and experimental setup, I will discuss first oscillation results from NOvA and the physics program of NOvA more broadly.

Host: Jon Link
December 9 (Wed)
4:00pm - 5:00pm
304 Robeson

(Poster)
Diana Vaman (University of Virginia)

Jet quenching in hot strongly-coupled N=4 superYang-Mills

The question of how far a high energy excitation travels through a plasma before stopping and thermalizing depends crucially on whether the plasma is strongly or weakly interacting. (It also depends crucially on the energy and momentum of the jet.) I will address this problem in the context of a strongly coupled plasma, using the methods of AdS/CFT. By adding higher-derivative terms to the supergravity action, one builds an expansion in inverse square-root powers of the 't Hooft coupling constant, and can move away from the infinite-coupling limit. I will present their effect on the jet's maximal stopping distance.

Host: Lara Anderson
December 16 (Wed)
4:00pm - 5:00pm
304 Robeson
Final Exam Week

December 23 (Wed)
4:00pm - 5:00pm
304 Robeson
Winter Break

December 30 (Wed)
4:00pm - 5:00pm
304 Robeson
Winter Break

January 2016
Jan 6 (Wed)
4:00pm - 5:00pm
304 Robeson
Winter Break

Jan 13 (Wed)
4:00pm - 5:00pm
304 Robeson
Winter Break

Jan 20 (Wed)
4:00pm - 5:00pm
304 Robeson
RESERVED

Host:
Jan 25 (Mon)
4:00pm - 5:00pm
304 Robeson

RESERVED

Host:
February 2016
Feb 3 (Wed)
4:00pm - 5:00pm
304 Robeson

RESERVED

Host:
Feb 10 (Wed)
4:00pm - 5:00pm
304 Robeson

(Poster)
Youngjoon Kwon (Yonsei University)

Searches for Exotic Phenomena from Belle

The Belle experiment (in KEK, Japan) has produced numerous new results in heavy-flavor physics, including discoveries of CP violations in B meson, several electroweak penguin decays of B, and exotic hadronic states such as X(3872) and Z(4430)+. Belle has also produced many studies of exotic phenomena that are either forbidden or unexpected in the Standard Model (SM).

In this seminar, two recent highlights of Belle will be presented. First, we present the measurements of B -> D(*) tau nu. In the SM, it is produced as ordinary semileptonic decays and the expected branching fractions are calculated reliably. If there is, for example, a charged Higgs boson from a new physics beyond the SM, the branching fractions will be modified. Therefore, these decays provide excellent probe for physics beyond SM. Next, we present the search for dark photon and dark higgs from Belle. In many hypotheses of dark sector, the set of dark-matter particles among which they interact, a U(1) gauge interactions are proposed, in which a 'dark photon' is mediating the interaction and a 'dark higgs' provides spontaneous symmetry-breaking. Our results have been obtained by analyzing the full data sample of Belle.

Host: Leo Piilonen
Feb 17 (Wed)
4:00pm - 5:00pm
304 Robeson
RESERVED

Host:
Feb 24 (Wed)
4:00pm - 5:00pm
304 Robeson

(Poster)
David Vanegas Forero (Virginia Tech)

Testing New Physics with Oscillation Neutrino Experiments

Neutrino oscillations are irrefutable evidence of Standard Model (SM) incompleteness by requiring a non-zero neutrino mass. It is expected that models generating neutrino masses might also provide new neutrino interactions. A long standing framework to include Non-Standard Neutrino Interactions (NSI) is by adding four fermion neutrino interactions with general couplings to the SM. In this talk I will review some assumptions and conditions in order to have a 'large' NSI, the current bounds, and the effect of the NSI at the probability level. Finally, the NSI impact in the determination of the neutrino oscillation parameters will be discussed in the light of the future neutrino program.

Host: Patrick Huber
March 2016
March 2 (Wed)
4:00pm - 5:00pm
304 Robeson
RESERVED

Host:
March 9 (Wed)
4:00pm - 5:00pm
304 Robeson
Spring Break

March 16 (Wed)
2:30-3:30
304 Robeson

Joshua Qualls (Taiwan National University)

Exploring spectral bounds from modular invariance

In contrast with the usual techniques in higher-dimensional CFTs using crossing symmetry of correlators, we focus in this talk on a complementary technique in two dimensions known as the "modular bootstrap"--constraints following from imposing modular invariance of the partition function on the torus. After presenting recent results, we discuss intriguing results from work in progress using toroidal compactification to generate CFTs in order to probe these constraints. If time allows, I will also discuss more recent work toward analytic results in conformal and superconformal field theories.

Host: Djordje Minic
March 16 (Wed)
4:00pm - 5:00pm
304 Robeson

(Poster)
Chen Sun (Virginia Tech)

The 750 GeV diphoton excess in unified Pati-Salam models from noncommutative geometry

We discuss a possible interpretation of the $750$ GeV diphoton resonance, recently reported at the LHC, within a class of Pati-Salam models with gauge coupling unification. The unification is imposed by the underlying non-commutative geometry (NCG), which in these models is extended to a left-right symmetric completion of the Standard Model (SM). Within such unified Pati-Salam models the Higgs content is restrictively determined from the underlying NCG, instead of being arbitrarily selected as in canonical, non-unified, Pati-Salam models. We show that the observed cross sections involving the $750$ GeV diphoton resonance could be realized through a SM singlet scalar field accompanied by colored scalars, present in these unified models. In view of this result we discuss the underlying rigidity of these models in the NCG framework and the wider implications of the NCG approach for physics beyond the SM.

Host: Tatsu Takeuchi
March 22 (Tue)
2:30pm - 3:30pm
304 Robeson

(Poster)
Special Date and Time
Mary Hall Reno (University of Iowa)

Prompt neutrinos from charm: atmospheric and beam dump fluxes

Neutrinos from charmed hadrons produced by cosmic ray interactions with air nuclei are the main background to high energy astrophysical neutrino flux measurements. Using next-to-leading order QCD production of charm pairs, nuclear corrections, and multi-component models of the incident cosmic ray flux, we make a new theoretical evaluation of the flux of prompt neutrinos from charmed hadron production and decay in the atmosphere. Collider results on charm pair production help constrain the range of renormalization and factorization scales in the NLO cross section. A related evaluation of the tau neutrino flux from charm production shows that the proposed beam dump experiment SHiP would have an unprecedented opportunity to study tau neutrino interactions directly.

Host: Leo Piilonen
March 30 (Wed)
4:00pm - 5:00pm
304 Robeson

(Poster)
Mauricio Bustamante (OSU)

Probing neutrino lifetime using high-energy astrophysical neutrinos

In theories beyond the Standard Model, neutrinos may be unstable and decay with rates that have detectable effects. The cumulative effect of decay on a neutrino flux will be larger the longer the baseline. Therefore, the high-energy (10 TeV -- 2 PeV) astrophysical neutrinos recently discovered by IceCube --with estimated baselines from several megaparsecs to a few gigaparsecs-- are fertile ground to test decay. I will show how decay distorts the flavor composition of these neutrinos and the rate of neutrino-induced showers. Using these observables, existing and near-future IceCube data improve the lifetime bounds by several orders of magnitude, in the normal and inverted neutrino mass hierarchy.

Host: Shunsaku Horiuchi
April 2016
April 6 (Wed)
2:30pm - 3:30pm
304 Robeson


Special Time
(Poster)
Per Berglund (University of New Hampshire)

On generalized complete intersection Calabi-Yaus and K3-fibrations

We study certain classes of Calabi-Yau manifolds following the recent work on generalized complete intersections by Anderson et al. In particular we focus on those that are obtained from higher dimensional analogs of Hirzebruch surfaces, and find novel K3-fibrations.

Host: Lara Anderson
April 13 (Wed)
4:00pm - 5:00pm
304 Robeson

(Poster)
Bogdan Dobrescu (Fermilab)

Di-photon and other di-boson resonances at the LHC

The LHC Run 2, with collisions at a center-of-mass energy of 13 TeV, is opening a window towards the laws of nature at the shortest distances directly accessible so far. Some observed events suggest that there may exist a new spin-0 particle that decays into a pair of photons. Other events seem to be consistent with a spin-1 particle that decays into an electron and a right-handed neutrino. I will discuss some challenges in identifying theories that may include such particles, as well as additional ways to test them.

Host: Tatsu Takeuchi
April 20 (Wed)
4:00pm - 5:00pm
304 Robeson

(Poster)
Ian Shoemaker (Penn State)

Flavor and Spectral Probes of New Neutrino Physics at IceCube

The IceCube neutrino observatory has observed a new source of ultrahigh energy neutrinos extending to PeV energies and apparently originating from outside the Milky Way. The high energies and long distances traveled by these neutrinos make them excellent probes of new physics in the neutrino sector that is otherwise hidden from us. Using both current and projected future data I will discuss the sensitivity of spectral and flavor information at IceCube to a variety of new physics scenarios. Interestingly, the sensitivity to neutrino self-interactions is complementary to that offered by early universe physics. Lastly, I will illustrate this complementarity in a sterile neutrino model that is motivated by the tension in short-baseline and cosmological data.

Host: Shunsaku Horiuchi
April 27 (Wed)
4:00pm - 5:00pm
210 Robeson


Special Room
(Poster)
Peter Shawhan (University of Maryland / Joint Space-Science Institute))

The Remarkable Story of LIGO's Detection of Gravitational Waves

On February 11, LIGO scientists announced the direct detection of gravitational waves, confirming a century-old prediction of Einstein's general theory of relativity. This milestone was finally made possible with the incredibly sensitive Advanced LIGO detectors, combined with a certain measure of luck. This first event is already enough to investigate the properties of the source, test the theory of gravity, and project what more we can learn from future events. I will share both the scientific meaning of the discovery and some of the personal stories behind it.

Host: Djordje Minic
May 2016
May 3 (Tue)
4:00pm - 5:00pm
304 Robeson


Special Date
(Poster) (Presentation)
Oscar Zapata (University of Antioquia)

Phenomenology of Models with radiative Neutrino Masses and Dark Matter

In this talk we will present the phenomenology of some TeV-scale models, known as scotogenic models, that can simultaneously explain neutrino masses and account for the dark matter. In these models, non-zero masses are generated radiatively at the 1-loop level and the dark matter candidate is one of the particles mediating the loop diagram, which are assumed to be odd under a Z2 symmetry. The compatibility of the models with the constraints coming from lepton flavor violation processes, oblique parameters, dark matter, colliders and neutrino oscillation data will be discussed. .

May 11 (Wed)
4:00pm - 5:00pm
304 Robeson

Final Exam Week