events - Page 51
Susanne Viefers, UiO
In recent years there has been substantial interest in the study of strongly correlated states of cold atoms, analogous to exotic states known from low-dimensional electron systems - one 'holy grail' being experimental realisation of quantum Hall-like states in atomic Bose condensates. In particular there have been many studies on the rotational properties of cold atom systems, as rotation is the conceptually simplest way of simulating a magnetic field for electrically neutral atoms. Even richer physics is expected in the case of two-species gases, such as mixtures of two types of bosonic atoms.
In this talk I will give an introduction to the field, followed by some recent results on the rotational properties of two-species Bose gases in the lowest Landau level. In particular we show that, contrary to expectations, trial wave functions of the composite fermion (CF) type, known from quantum Hall physics, give a very accurate description of this system. It is also shown how working only with a certain subset of possible CF candidate wave functions constitutes a major computational simplification without much loss of accuracy for the low-lying states. Finally I will briefly discuss some striking mathematical identities between seemingly different CF candidate states, of interest for a better understanding of the CF method in general.
Each year in spring, research institutes and universities around the world invite high-school students for a day-long programme to experience life at the forefront of basic research. These International Masterclasses give students the opportunity to be particle physicists for a day by analysing real data from the Large Hadron Collider, or LHC, at CERN.
New physics in charm sector
Abram Krislock, UiO
During Supersymmetry phenomenology research, involving simulations of the Large Hadron Collider experiments, a certain mistrust of data analysis using common histograms arose. Someone once said, "Change the bins and try the fit again..." A quest began to eliminate the bins entirely. After a recent study, it was clear that a deeper understanding of statistics was needed to complete this quest. A new probability calculus was discovered, leading to an interesting new data smoothing technique.
Each year in spring, research institutes and universities around the world invite high-school students for a day-long programme to experience life at the forefront of basic research. These International Masterclasses give students the opportunity to be particle physicists for a day by analysing real data from the Large Hadron Collider, or LHC, at CERN.
Synthesis and characterization of free standing Pt-Rh nanoparticles, and 2 wt. % Pt 0.70 Rh 0.30 /Al2O3 and 20 wt. % Co1xRex/Al2O3 (0.00 ≤ x ≤ 0.15) metal-on-support catalysts
Carsten Lütken, UiO
The new states of matter and concomitant quantum critical phenomena revealed by the quantum Hall effect appear to be accompanied by an emergent modular symmetry. The extreme rigidity of this infinite symmetry makes it easy to falsify, but two decades of experiments have failed to do so, and the predicted location of quantum critical points is in accurate agreement with experiments.
The symmetry severely constrains the effective low energy physics of 1010 charges in two dirty dimensions. A toroidal σ‐model gives a critical exponent that is in close agreement with numerical simulations. A double scaling law uncovered in the data suggests that the wave‐function may be multi‐fractal.
The modular analysis can be extended to “relativistic” group IV materials like graphene, silicene, germanene and stanene, and where reliable data are available there appears to be agreement.
C.A. Lütken, Introduction to the role of modular symmetries in graphene and other 2-‐dimensional materials, Contemp. Phys. (2014), http://dx.doi.org/10.1080/00107514.2014.949445
C.A. Lütken, G.G. Ross, Quantum critical Hall exponents, Phys. Lett. A 378 (2014) 262–265, http://dx.doi.org/10.1016/j.physleta.2013.11.001
Pasquale Dario Serpico, LAPTh, Univ. de Savoy, CNRS
Despite its remarkable success, the Standard Model (SM) of particle physics does not address key facts revealed by cosmological and astrophysical observations. Until now, no signs of new physics have been discovered in laboratory experiments, leaving unclear what is the path chosen by Nature for the physics beyond the SM (BSM). I will discuss in this talk how indirect signals from Dark Matter (DM) might help us in this challenging "theoretical selection problem", with implications on foundational aspects of BSM physics. I will illustrate this point with possible DM interpretations of recent anomalies in multimessenger observations of energetic radiation of Galactic and extragalactic origin.
Universality in the AC Conductance of Keratinized Tissues
Statistical Analysis of Concentration Fluctuations as Detected by LIDAR backscatter
Development and application of a method for imaging interstitial iron distribution in multicrystalline silicon
Self-improving CNC milling machine
Jesús Zavala Franco, University of Copenhagen [slides]
Although there is substantial gravitational evidence for the existence of dark matter, its nature as a new particle beyond the Standard Model remains one of the biggest mysteries in modern astrophysics. The favourite theoretical model, Cold Dark Matter (CDM), assumes that non-gravitational dark matter interactions are irrelevant for galaxy formation and evolution.
Surprisingly, there is no strong evidence for the CDM hypothesis. Current astronomical observations allow significant departures that have a relevant impact on our understanding of how galaxies form and evolve. Moreover, the observed properties of the smallest galaxies have been consistently in conflict with the predictions of the CDM model.
In this talk, I will argue that to explain galaxy formation and evolution in the broadest sense, an effective dark matter theory must contain a wider range of dark matter particle physics without spoiling the success of CDM in reproducing the large-scale structure of the Universe, while addressing its outstanding challenges at the scales of individual galaxies.
Syntese- og diffraksjonsstudie av faser i systemene Nb–Fe–Sb og Ti–Co–Sn
Ivica Picek, Univ. of Zagreb
After the discovery of the Higgs boson, searching for the dark matter (DM) is one of the main targets for the LHC. In light of evidence for neutrino mass it would be appealing that DM particles account for a solution to the small neutrino mass. A radiative neutrino mass realization dubbed "scotogenic" (with DM particles in a loop) imposes an exactly conserved Z_2 symmetry to eliminate tree-level neutrino masses and to simultaneously stabilize a DM candidate.
In this talk I will discuss the possibility to avoid such ad hoc Z_2 symmetry: either by promoting it to a local gauge U(1)_D symmetry or by requiring that it arises "accidentally" (on account of the SM symmetry and a choice of the field content). In this context, I will discuss the testability of Majorana singlet, triplet and quintet DM candidates at the LHC.
Alejandro Ibarra, Technische Universität München [slides]
The search for the gamma-rays which are presumably produced in dark matter annihilations is hindered by the existence of large, and still poorly understood, astrophysical backgrounds. In this talk we will emphasize the importance of sharp spectral features for the identification of a dark matter signal. We will review the status of the search of the various spectral features that arise in Particle Physics scenarios and we will discuss the interplay with other search strategies.
Diffraction effects in sonar array
Near-field Characterization of Sonars
Total Pressure Wavefield Computation for Rough Sea-Surfaces
Pat Scott , Imperial College London [slides]
Searches for particle physics beyond the Standard Model come in many forms, from searches for new particles at accelerators to gamma-ray and neutrino telescopes, cosmic ray detectors and ultra-clean experiments deep underground. Efforts to combine multiple search channels in 'global fits' to new physics scenarios typically consider only a subset of the available channels, and apply them to a very small range of possible theories. Astroparticle searches in particular are usually only included in a very approximate way, if at all. In this talk I will review recent progress in improving this situation, and preview some of the future developments and challenges in this field.
Michael Kachelriess, NTNU [slides]
The IceCube Collaboration announced 2012 evidence for the first detection of extraterrestrial neutrinos. Meanwhile, the discovery of a extraterrestrial neutrino flux (of surprisingly large magnitude) has been established. After a review of the basic ideas of high-energy neutrino astrophysics, I discuss possible sources for these neutrinos and their signatures. I discuss the neutrino yield from collisions of cosmic ray nuclei with gas and the possibility that Galactic sources can explain the IceCube excess. I review also the cascade bound on extragalactic neutrinos and its consequences.
Assessing glucose metabolism in tumor and normal tissues for patients with lung cancer following fractionated radiotherapy
Jörn Kersten, Universitetet i Bergen [slides]
Despite the astonishing success of the standard LambdaCDM cosmological scenario, there is mounting evidence for a tension with observations. For example, some measurements indicate that a part of the dark matter is hot. In addition, the observed properties of relatively small galaxies do not quite agree with the predictions by simulations of structure formation.
I will discuss a simple particle physics model containing cold dark matter (DM) and sterile neutrinos. Both are charged under a new gauge interaction. The resulting DM self-interactions and DM-neutrino interactions resolve the problems with structure formation. The sterile neutrinos can account for both a small hot DM component and the neutrino anomalies found in short-baseline experiments.