UCL HEP Seminars 2014
12/12/2014 : Teppei Katori (QMUL)
Liquid argon detector R&D in USA
Liquid Argon time projection chamber (LArTPC) is the candidate technology for the next generation large neutrino detectors. Unprecedented resolution and capability of particle ID (ionization energy loss, scintillation light) make it attractive for future high precision neutrino experiments. The necessary technologies were developed by the ICARUS collaboration in Italy and they are further studied in USA. In this talk, I would like to describe the overview of the LArTPC efforts in USA, with a special emphasis on the liquid argon scintillation light detection technology.
05/12/2014 : Gary Royle (UCL)
Proton and Advanced Radiotherapy
Radiation therapy is a technology based clinical area which uses an array of photons and particles to target cancer sites. It has a number of areas in common with high energy physics. The talk will cover the basis of radiation therapy, the future technological needs, areas where high energy physicists can get involved from research to careers, and will highlight some clinical problems within the treatment of cancer patients that are relevant to the translation of high energy physics concepts and technology.
01/12/2014 : Jorge S Diaz (KIT)
Extra ordinary seminar: Testing Lorentz and CPT invariance with neutrinos (NEMO-3 and (Super)NEMO data)
Lorentz symmetry is a cornerstone of modern physics. As the spacetime symmetry of special relativity, Lorentz invariance is a basic component of the standard model of particle physics and general relativity, which to date constitute our most successful descriptions of nature. Deviations from exact symmetry would radically change our view of the universe and current experiments allow us to test the validity of this assumption. In this talk, I will describe how we can search for deviations from exact Lorentz and CPT invariance with neutrino oscillations, time-of-flight measurements, ultra-high-energy neutrinos, and double beta decay.
28/11/2014 : Prof. Philip Burrows (Oxford)
Precison Higgs Physics: The International Linear Collider Higgs Factory
An international team has recently completed the Technical Design Report for the International Linear Collider (ILC). The ILC is an electron-positron collider with a design target centre-of-mass energy of 500 GeV. Following the Higgs boson discovery it has been proposed to realise the ILC by building a 250 GeV ‘Higgs Factory’, and subsequently to upgrade it in stages to higher energies of 350 GeV, where it would also serve as a ‘top factory’, and eventually to 500 GeV to allow access to the top-Higgs and Higgs self- couplings. The Japanese particle physics community has proposed to host the collider in Japan. I will describe the programme of precision Higgs-boson measurements at the ILC. I will give an overview of the collider design, and report on the project status.
21/11/2014 : Richard Savage (Warwick)
Using machine learning to cure cancer (!)
Medicine is undergoing a data revolution. From whole-genome sequencing to digital imaging and electronic health records, new sources of data are promising to revolutionise how we treat disease. With these opportunities, however, come significant challenges. The data are often high-dimensional, noisy, with complex underlying structure. And we may wish to combine multiple data types from very different sources. I'll give a tour of some of these issues, focusing on some of the projects we're working on to use statistical machine learning to get the most out of these data and hence improve, in particular, the treatment and curing of cancer.
14/11/2014 : Stuart Mangles (Imperial)
Laser wakefield accelerators : a laboratory source of femtosecond x-ray pulses
Laser wakefield accelerators are now capable of accelerating electron beams up to 1 GeV in just 1 centimetre of plasma. During the acceleration process the electron beam can oscillate, producing very bright femtosecond duration x-rays. In this talk I will introduce some of the key concepts of laser wakefield acceleration and x-ray generation. The x-rays we can generate have some highly useful properties including an ultra short (few femtosecond) duration, micrometer sized source and broad spectral coverage. I will discuss the use of this unique source of x-rays for applications such as probing matter under extreme conditions and medical imaging.
07/11/2014 : Cristina Lazzeroni (Birmingham)
Search for rare and forbidden Kaon decays at NA62
The NA62 Kaon programme will be reviewed. A selection of recent results on rare and Standard Model forbidden kaon decays will be presented, and the current status of the experiment and prospects for the measurement of the decay K+ to pi+ nu nubar will be summarised.
31/10/2014 : Malcolm Fairbarn (Kings College)
Future Dark Matter searches and the Neutrino Background.
I will describe very simple models of dark matter and show how even with reasonable masses, effects such as resonances can lead to very small cross sections at direct detection experiments. I will then briefly discuss the usefulness in slightly more complicated simplified models than the effective operator approach. I will then present some work constraining such models using dijet studies at the LHC and indirect detection and show how direct detection cross sections can be very small in such scenarios, even with good relic abundance. Small cross sections run the risk of being potentially undetectable due to the neutrino background, even with very large future direct detection experiments. I will spend the rest of my talk explaining future strategies for getting the dark matter signal out of the neutrino background.
17/10/2014: Aurélien Benoit-Lévy (UCL)
Inflation, B-modes and dust: Planck's view on BICEP2 results.
The Planck collaboration has recently published new results on the characterisation of polarised dust emission at intermediate and high Galactic latitudes. Although these results specifically focus on the properties of Galactic dust, they are relevant for cosmological studies. Indeed dust is a known contaminant of the long sought-after primordial B modes from Inflation. In this talk, I will focus on how these new results from Planck impact the interpretation of the recent claims from the BICEP2 collaboration.
24/09/2014 : 13:00-17:00 : HEP Group Day (E3/E7)
23/09/2014 : 10:30 - 16:00 : 1st Year PhD Talks (E3/E7)
11/09/2014 : Richard Ruiz (University of Pittsburgh)
State-of-the-Art Tests of Lepton Number Violation and Seesaw Mechanisms at Hadron Colliders
13/06/2014 : Prof. Ulrik Egede (Imperial)
Search for HIdden Particles (SHIP) at the SPS
Particles physics faces the contradiction of a Standard Model, that seems perfect and can exist without corrections to the Planck scale, and the inability of the same Standard Model to explain dark matter, neutrino masses and baryogenesis. I will give a brief overview of the vMSM, a minimal extension to the Standard Model that may solve this contradiction. The vMSM predicts the existence of new GeV mass neutral leptons and I will present how a fixed target experiment located at a new beamline of the SPS is ideal to search for these. Possibilities for involvement of UK groups will be discussed.
27/05/2014 : Jouni Suhonen (University of Jyväskylä) - 2pm-3pm
Rare Weak Decays and Nuclear Structure
I will discuss different types of rare decays. I divide these decays in three categories: A. Decays with (ultra) low Q values; B. Decays between states with large differences in the initial and final angular momenta; C. Weak-interaction processes of higher order. The A category contains potential candidates for neutrino-mass measurements in beta decays. Category B highlights cases where single and double beta decays compete. Category C highlights the large variety of different double beta decays that are possible via exchange of a light Majorana neutrino. In particular, the less discussed positron-emission modes of double beta decays, including the interesting resonant neutrinoless double electron capture mode, are elucidated.
27/05/2014 : Mikhail Shaposhnikov (EPFL) - 4pm-5pm
Higgs inflation at the critical point
Higgs inflation can occur if the Standard Model is a self-consistent effective field theory up to inflationary scale. This leads to a lower bound on the Higgs boson mass, M_h > M_crit. If M_h is more than a few hundreds of MeV above the critical value, the Higgs inflation predicts the universal values of inflationary indexes, r= 0.003 and n_s= 0.97, independently on the Standard Model parameters. We show that in the vicinity of the critical point M_crit the inflationary indexes acquire an essential dependence on the mass of the top quark m_t and M_h, and can be consistent with BICEP 2 data.
16/5/2014, Phillipe Mermod (Geneva)
"Magnetic monopoles at the LHC and in the Cosmos"
Dirac showed in 1931 that the existence of one magnetic monopole in the Universe would explain why electric charge is quantised. The monopole also arises as a natural consequence of Grand Unification theories. While collider experiments provide direct laboratory studies, stable particles with masses beyond the reach of man-made accelerators could have been produced in the early Universe and still be present today. I shall review experimental searches for monopoles at colliders, focusing on recent developments at the LHC. I shall also provide a survey of monopole searches with cosmic-ray detectors and trapped in matter, and propose a few promising avenues for the future.
09/05/2014 : Moritz McGarrie (University of the Witwatersrand)
SUSY model building for a 126 GeV Higgs
his talk will review the current status of minimal models of supersymmetry breaking and explore two possible models which can achieve the correct Higgs mass and still allow for sparticles accessible to the LHC's reach. In the first example we use the HEP tool SARAH to build two tailor made spectrum generators to analyse a Higgs extension (non decoupled D-terms) of the MSSM. We then explore the LHC & ILC's capability to determine their effect through their enhancement of Higgs branching ratios with respect to the Standard Model. In the second model, we explore flavour-gauge mediation to obtain light 3rd generation squarks, whilst keeping the 1st and 2nd generation above exclusions. In particular this model can also generate non-degenerate 1st and 2nd generation squarks and, although in the framework of gauge mediation, leads to mild flavour changing neutral currents at, below and above current limits.
04/04/2014 : Dimitris Varouchas(LPNHE-Paris)
H -> tautau in ATLAS
In this seminar, a search for the Standard Model (SM) Higgs boson with a mass of 125 GeV decaying into a pair of tau leptons will be reported. The analysis is based on data samples of p-p collisions collected by the ATLAS experiment at the LHC, corresponding to an integrated luminosity of 20.3.0 1/fb at centre-of-mass energy of sqrt(s)=8 TeV. The observed (expected) deviation from the background-only hypothesis corresponds to a significance of 4.1 (3.2) standard deviations, and the measured signal strength is μ = 1.4+0.5 −0.4. This is evidence for the existence of H → τ+τ− decays, consistent with the Standard Model expectation for a Higgs boson with mH = 125 GeV. A brief comparison with the respective CMS result will be also presented.
28/03/2014 : MOVED to 31/03/2014 ! UCL third year students
MOVED! UCL third year student IOP practise talks!
The UCL third year student IOP practise talks will now be on Monday 31/03/2014!
21/03/2014 : Prof. Tegid Jones (UCL)
Forty years since the Neutral Current (Z0) Discovery in Gargamelle. The UCL Contribution.
The discovery of neutral currents (1973/74) was the first confirmation of the SU(2)xU(1) electro-weak unified theory. UCL HEP was part of the Gargamelle collaboration which made the first truly significant discovery at CERN. Forty years later the UCL-HEP group contributed to the discovery of the Higgs Boson, thereby completing the understanding of symmetry breaking in the SU(2)xU(1) model.
14/03/2014 : Ian P. Shipsey (Oxford)
The Large Synoptic Survey Telescope (for particle physicists)
Recent technological advances have made it possible to carry out deep optical surveys of a large fraction of the visible sky. These surveys enable a diverse array of astronomical and fundamental physics investigations including: the search for small moving objects in the solar system, studies of the assembly history of the Milky Way, the exploration of transient sky, and the establishment of tight constraints on models of dark energy using a variety of independent techniques. The Large Synoptic Survey Telescope (LSST) brings together astrophysicists, particle physicists and computer scientists in the most ambitious project of this kind that has yet been proposed. With an 8.4 m primary mirror, and a 3.2 Gigapixel, 10 square degree CCD camera, LSST will provide nearly an order of magnitude improvement in survey speed over all existing optical surveys, or those which are currently in development. Expected to begin construction later in 2014, and to enter commissioning in 2020, in its first month of operation LSST will survey more of the universe than all previous telescopes built by mankind. Over the full ten years of operation, it will survey half of the sky in six optical colors down to 27th magnitude. Four billion new galaxies and 10 million supernovae will be discovered. At least 800 distinct images will be acquired of every field, enabling a plethora of statistical investigations for intrinsic variability and for control of systematic uncertainties in deep imaging studies. LSST will produce 15 terabytes of data per night, yielding a data set of over 100 petabytes over ten years. Dedicated Computing Facilities will process the image data in near real time, and issue worldwide alerts within 60 seconds for objects that change in position or brightness. In this talk some of the science that will be made possible by the construction of LSST, especially dark energy science, which constitutes a profound challenge to particle physics and cosmology, and an overview of the technical design and current status of the project will be given.
28/02/2014 : Jo van den Brand (NIKHEF)
Probing dynamical spacetimes
Albert Einstein's theory of general relativity, published in 1915, gave science a radically new way of understanding how space, time and gravity are related. Gravity is defined as the curvature of spacetime and is caused by the four-momentum of matter and radiation. Einstein predicted that accelerating objects will cause vibrations in the fabric of spacetime itself, so-called gravitational waves. The detection of gravitational waves is the most important single discovery to be made in the physics of gravity. Gravitational waves exist in any theory of gravity that incorporates a dynamical gravitational field, be it a metric theory such as general relativity (or one of its generalizations), or a non-metric theory such as string theory. Observations of binary pulsars, whose orbital motion evolves in agreement with general relativity, revealed that gravitational radiation must exist. However, no direct observation of gravitational waves has been reported to date. Discovering gravitational waves would confirm once and for all that gravity is a fundamental dynamical phenomenon. The Virgo detector for gravitational waves consists mainly of a Michelson laser interferometer made of two orthogonal arms being each 3 kilometres long. Virgo is located within the site of EGO, European Gravitational Observatory, based at Cascina, near Pisa on the river Arno plain. Virgo scientists, in collaboration with LIGO in the USA and GEO in Germany, have developed advanced techniques in the field of high power ultra-stable lasers, high reflectivity mirrors, seismic isolation and position and alignment control. In 2015 these collaborations with turn on their advanced instruments in their quest for first detection of gravitational wave events.
26/02/2014 : George Efstathiou (Cambridge)
SPREADBURY LECTURE (JZ Young LT) : The Birth Of The Universe
Modern physics attempts to explain the full complexity of the physical world in terms of three principles: gravity, relativity and quantum mechanics. This raises important fundamental questions such as why is our Universe so large and old? Why is it almost, but not perfectly, homogeneous and isotropic? I will describe how recent measurements of the cosmic microwave background radiation made with the Planck Satellite can be used to answer these questions and to elucidate what happened within 10-35 seconds of the creation of our Universe.
21/02/2014 : Nikos Konstantinidis (UCL)
The High Luminosity LHC programme
As the LHC machine and experiments are preparing frantically to start data taking at design energy and luminosity (and slightly above), an equally intense and exciting programme of R&D and physics studies is ongoing for the High Luminosity (HL-) LHC project, proposed to start in about 10 years, that would deliver 3000/fb to each general purpose detector by the mid-2030s. I will discuss the science case for HL-LHC, the challenges for the accelerator and the experiments, and the ongoing R&D, particularly on the tracking and triggering systems of the experiments
14/02/2014 : Werner Vogelsang (UNI Tuebingen)
QCD resummation for jet and hadron production
Cross sections for the production of jets or identified hadrons in pp collisions play an important role in particle physics. At colliders, jets are involved in many reactions sensitive to new physics and their backgrounds. In lower-energy collisions, produced hadrons probe the inner structure of the nucleon and the fragmentation process. Both observables have in common that their use crucially relies on our ability to do precision computations of the underlying hard-scattering reactions in QCD perturbation theory. In this talk, we discuss the role of higher-order QCD corrections to these reactions. Specifically, we address the resummation of large logarithmic "threshold" corrections to the relevant partonic cross sections. Among other things, this allows us to determine dominant next-to-next-to-leading order QCD corrections to jet production at the LHC and Tevatron. Detailed phenomenological studies are presented.
07/02/2014 : Paschal Coyle (In2p3, France)
Neutrinos out of the blue
The road to neutrino astronomy has been long and hard. The recent observation of a diffuse flux of cosmic neutrinos by IceCube heralds just the start of this new astronomy. In this seminar a brief outline of the various experimental efforts worldwide to detect cosmic neutrinos are described and a selection of the physics results presented. Particular emphasis is given to ANTARES, a neutrino telescope located in the deep sea 40km off the southern coast of France. The European neutrino astronomy community has recently started the construction of KM3NeT, a several cubic kilometre neutrino telescope in the Mediterranean Sea. The plans of this new research infrastructure are described. Finally, the potential for a measurement of the neutrino mass hierarchy, with a densely instrumented detector configuration in ice (PINGU) and water (ORCA) is discussed.
31/01/2014 : Alexander Mitov (Cambridge)
Recent developments in top physics at hadron colliders
I will review the available NNLO results for top pair production at hadron colliders and will demonstrate their effect on various analyses of SM and bSM physics. I will then discuss the prospects for further NNLO level calculations in top physics and how they may influence existing results and open problems in top physics and beyond.
24/01/2014 : Jennifer Smillie (University of Edinburgh)
Jets, Jets, Higgs & Jets
The LHC is pushing the limits of our theoretical descriptions, especially in multi-jet processes. I will discuss the challenges posed by the large higher-order perturbative corrections, and describe the High Energy Jets framework which provides an alternative all-order description encoding the dominant pieces of the hard-scattering matrix elements. I will illustrate the effectiveness of this method with comparisons to LHC data, and what it teaches us about QCD at the LHC. In the last part of the talk, I will discuss the importance of this in the light of Higgs+dijets studies with an emphasis on vector boson fusion (VBF) channels and will discuss the implications of the previous results. I will show some results from ongoing work to describe the impact of VBF cuts on the gluon-gluon fusion contribution.