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HEP Seminars

04 Apr 2020

UCL HEP Seminars 2016

16/12/2016 Eric Jansen (CMCC)

Numerical ocean modelling and the case of MH370

In this seminar I will take you on a small excursion into the world of numerical ocean modelling, and more specifically: data assimilation. The field of ocean data assimilation is concerned with updating ocean forecasts using daily observations of the ocean state in order to produce more accurate forecasts for the next day. Observations are incredibly diverse: buoys and moorings that measure time-series in a specific location, autonomous vehicles that can dive and resurface, coastal radar systems that measure currents, but also satellite measurements of the sea surface. I will discuss how we can assimilate these observations using a Kalman filter technique, applied to an ensemble of ocean model realisations. The second part of the seminar will focus on how we can apply these ocean models to a real-world problem: the disappearance of flight MH370. Malaysia Airlines flight 370 was a commercial flight from Kuala Lumpur to Beijing, which vanished without a trace in March 2014. It is believed to have crashed somewhere off the west-coast of Australia, but despite extensive search operations the main wreckage was never found. Now, more than two years later, parts belonging to the aircraft are found 4000km away on the African coast. How can we use this information to locate the crash site?

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NOTE UNUSUAL DAY!: 14/12/2016 Prof. Un-Ki Yang (Seoul National Univ.) 4pm, UNUSUAL LOCATION: E7

Searches for heavy neutrinos at the LHC

Heavy neutrinos occur in various extensions of the Standard Model (SM) and may explain the observed small masses of the SM neutrinos via several possible variants of the seesaw mechanism. We present results on searches for heavy neutrinos at the LHC. Searches are performed in the dilepton+jets channel and the trilepton channel, and results are interpreted in terms of the Left-Right Symmetrical model, Type-I, and the Type-III seesaw mechanism.

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02/12/2016 Clare Burrage (Nottingham)

Detecting Dark Energy with Atom Interferometry

I will discuss the possibility that the nature of the dark energy driving the observed acceleration of the Universe on giga-parsec scales may be determined first through metre scale laboratory based atom interferometry experiments. I will begin by discussing why our attempts to solve the cosmological constant problem lead to the introduction of new, light degrees of freedom. In order to be compatible with fifth force constraints these fields must have a screening mechanism to hide their effects dynamically. However, this doesn’t mean that they are impossible to detect. I will discuss the constraints that arise from a range of laboratory experiments from precision atomic spectroscopy to collier physics. Finally I will show that atom-interferometry experiments are ideally suited to detect a large class of the screening mechanisms known as chameleon. This will then allow us to either rule out large regions of the chameleon parameter space or to detect the force due to the dark energy field in the laboratory.

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25/11/2016 Lucian Harland-Lang (UCL))

Photon-photon collisions at the LHC

I will discuss the possibilities for using the LHC as a photon colliding machine. The colour singlet nature of the photon means that it can readily lead to exclusive or semi-exclusive events, with limited or no extra particle production in the final state. I will show how such processes provide a well understood environment in which to test the Standard Model and search for BSM physics. This is particularly relevant at the LHC, where these events may be selected using dedicated 'proton tagging' detectors installed in association with ATLAS and CMS. I will also consider the impact of photon-initiated processes on the more common inclusive production modes at the LHC. Here, the photon must be included in addition to the quarks and gluons as a parton in the proton. I will demonstrate that, despite indications to the contrary from earlier studies, the photon parton density in the proton is in fact quite precisely known, and consider the implications for LHC (and FCC) phenomenology.

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18/11/2016 James Currie (IPPP Durham)

Jet Production at NNLO

Jet production is one of the most ubiquitous yet important reactions at the LHC. Calculating higher order corrections to this observable allows us to gain sensitivity to phenomenological parameters such as the strong coupling and the gluon PDF as well as providing a rigorous test of QCD over a vast kinematic range. It is well known that calculating higher order corrections is a non-trivial task and requires a powerful method to subvert the various infrared singularities present in the calculation. I will introduce the Antenna Subtraction method as a means of calculating finite cross sections and present some recent results obtained by applying this method to the problem of jet production at NNLO.

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11/11/2016 Marcel Vos (IFIC Valencia))

Future of top Physics

In this seminar I discuss the potential of planned facilities - lepton and hadron colliders - to bring our understanding of the top quark to the next level. The focus is on measurements of top quark properties and interactions with exquisite sensitivity for signals of the physics that lies behind the Standard Model: the top quark mass measurement, the search for FCNC interactions involving top quarks and those characterizing the top quark couplings to the gluon, EW gauge bosons and the Higgs boson. The precision that new experiments can achieve in these key measurements is compared to the current state-of-the-art and the expectation for the complete LHC programme.

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04/11/2016 Marco Pappagallo (University of Bari & INFN)

exotic hadronic states in LHCb (Penta/Tetra quarks)

The latest years have seen a resurrection of interest in searches for exotic states. Using the data collected at pp collisions at 7 and 8 TeV by the LHCb experiment, unambiguous new observations of exotic charmonia hadrons produced in B and Lambdab decays are presented. Results of a search for a tetraquark state decaying to Bs pi+- are reported as well

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28/10/2016 Jeff Foreshaw(Manchester) NOTE: earlier time: 3pm! different room: E7!

“Probabilities and Signalling in Quantum Field Theory”

I will talk about a way to compute transition probabilities that works directly that the level of probabilities and not amplitudes. The formalism guarantees that the initial and final states are always linked by a chain of retarded propagators and it has a nice diagrammatic approach.

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26/10/2016 NOTE time and place!

Gravitational Wave Symposium

26th October 14.00 Imperial College London, Blackett Laboratories LT1 lecture theatre
A half day physics meeting on gravitational waves. Leading scientists from the Astro and HEP communities will present the recent discovery of gravitational waves and future prospects of this new field in fundamental physics. The talks are aimed at interested researchers at all levels across all of London's universities. See: https://indico.cern.ch/event/563302

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21/10/2016 2nd year PhD Students, NOTE different time/place!

2nd year PhD talks!

1pm-5pm in E3/E7

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14/10/2016 Sally Shaw (UCL)

The LUX & LZ Dark Matter Experiments: WIMP Hunting in the Black Hills

Discovery of the nature of dark matter is recognised as one of the greatest contemporary challenges in science, fundamental to our understanding of the universe. Weakly Interacting Massive Particles (WIMPs) that arise naturally in several models of physics beyond the Standard Model are compelling candidates for dark matter. The LUX experiment, operated 1.5 km underground in the Davis Cavern of the SURF laboratory, USA, is the world leader in the direct hunt for WIMPs. I will present the latest LUX results and describe the unique in-situ calibrations that have allowed low energy nuclear recoil measurements in liquid xenon, greatly enhancing our sensitivity to low mass WIMPs. I will also discuss the status of LUX’s multi-tonne successor, LZ, demonstrating how its sensitivity is ideally matched to explore the bulk of the remaining theoretically favoured electroweak phase space towards galactic dark matter discovery.

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07/10/2016 Leszek Roszkowski (Sheffield and NCBJ)

Particle dark matter: what it is and how to determine its properties

After a brief introduction I will comment on some recently discussed WIMP candidates for dark matter. In particular, I will provide arguments that a supersymmetric neutralino with mass around 1 TeV and well defined properties has emerged as an attractive and experimentally testable candidate for dark matter in light of measured Higgs boson properties and ensuing implications for supersymmetry searches at the LHC. On the other hand, for a wide range of WIMPs, and independent of any specific particle physics scenarios, when a dark matter signal is eventually measured in direct or indirect search experiments, or both, it may prove rather challenging to work out ensuing WIMP properties.

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19/07/2016 Mark Scott (TRIUMF)

T2K and NuPRISM: An experimental solution to the problems of neutrino interactions in long baseline neutrino experiments

T2K is a long baseline neutrino experiment in Japan that has published world-leading measurements of neutrino oscillations and has the potential to find evidence of CP violation in the lepton sector. The first half of this talk will give a brief description of neutrino oscillations before presenting the latest neutrino oscillation results from the T2K experiment. The difficulties of neutrino interaction modelling and how this affects oscillation analyses will be discussed before introducing the NuPRISM detector. NuPRISM is an intermediate water Cherenkov detector that continuously samples the neutrino beam across a range of off-axis angles. This detector can remove the problems associated with neutrino interactions by recreating the oscillated far detector spectrum using near detector data. The second half of the talk will describe the NuPRISM analysis method, highlighting the unique abilities of the detector and will present an oscillation analysis that is insensitive to incorrect neutrino interaction modelling.

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1/07/2016 Srubabati Goswami (Physical Research Laboratory, Navrangpura, Ahmedabad)

Probing the Leptonic CP violation in current and future experiments

In this talk I will summarize the current status of the CP phase in the lepton sector. I will discuss the main difficulties associated with the measurement of this parameter. In particular I will discuss the problem of parameter degeneracies. How the synergy between beam based and atmospheric neutrino experiments can help in the determination of the CP phase will be shown. I will also discuss the sensitivity of the DUNE experiment to measure this parameter.

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17/06/2016 Andreas Korn (UCL)

Impressions from DM@LHC2016

I will give my personal impressions from the Dark Matter workshop DM@LHC2016. Slides from my own talk, titled "Latest results in the mono-jet and di-jet channels" will be reused and augmented by selected highlights from a spectrum of other talks.

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10/06/2016 Suchita Kulkarni (HEPHY Viena)

Impact of LHC monojet searches on new physics scenarios

Dark matter searches at the LHC are exploring new models and new regime with every new result. I take a specific example of monojet dark matter searches at the LHC and sketch their impact on two dark matter scenarios. I discuss the complementarity of the results with the direct and indirect detection searches. The two models under considerations are, dark matter motivated explanations of the 750 GeV diphoton excess and dark matter interactions with the Standard Models involving derivative couplings.

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03/06/2016 Miguel Arratia (Cambridge)

"Inelastic proton-proton cross-section at 13 TeV with ATLAS,

The inelastic proton-proton cross-section is a basic property of proton interactions, yet it cannot be calculated from first principles. In 1973 experiments at CERN discovered that it rises with energy—as Heisenberg had predicted. Today, the LHC sets the energy frontier at 13 TeV, and theory predicts an asymptotic “black-disk” limit. In this seminar, I will present a recent measurement of the inelastic cross-section with the ATLAS detector. One of the key ingredients for this study is the rate at which the LHC produces proton collisions—the luminosity. I will illustrate how we measure the LHC luminosity and achieve a percent-level accuracy. Finally, I will describe how this result relates to one of the open questions in cosmic ray physics. "

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27/05/2016 Heidi Sandaker (Oslo)

“The AEGIS experiment”

The AEGIS experiment, situated at the Antimatter Decelerator (AD) at CERN aim to measure for the first time the Earth’s gravitational acceleration of anti-Hydrogen. To achieve this the AEGIS collaboration plan to produce a pulsed cold anti-Hydrogen beam and send it through a classical Moire deflectometer before the anti-Hydrogen is detected by a system of position sensitive detectors. Beyond the gravitational measurements, AEGIS will also provide long-term anti-matter spectroscopy measurements. This talk will present both the scope and current status of the AEGIS experiment as well as discuss future measurements.

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13/05/2016 Kazuki Sakurai (Durham)

“Search for Sphalerons: LHC vs. IceCube"

In a recent paper, Tye and Wong (TW) have argued that sphaleron-induced transitions in high-energy interactions should be enhanced compared to previous calculations, based on a construction of a Bloch wave function in the periodic sphaleron potential and the corresponding pass band structure. In this talk, I present our resent work studying future prospects of observing sphaleron transitions at high energy hadron colliders and IceCube, based on TW results. I first discuss the production rate and possible signatures of the sphaleron-induced processes at high energy hadron colliders. We recast the early ATLAS Run-2 search for microscopic black holes to constrain the rate of sphaleron transitions at 13 TeV LHC. In the second half of the talk, I will discuss the possibility of observing sphaleron transitions induced by cosmogenic neutrinos at IceCube. I calculate the sphaleron event rate at IceCube and discuss the signature of such events. Finally I compare the performance of the sphaleron searches at the LHC and IceCube and find complementarity of these experiments.

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06/05/2016 David Hesketh (Tradinghub)

Financial Rogue Trading and Market Abuse – Finding the Signal in the Noise

The actions of Jerome Kerviel and Kweku Adobole resulted in billion dollar losses for SocGen and UBS. Similarly, the FX and LIBOR scandals have seen banks fined in the hundreds of millions of dollars. This presentation asks why the banks struggle to identify the signals left by these traders. Topics covered include what the traders were doing in each case, the big data statistical approaches used by the anti-terrorist sections of the CIA and MI5 that have been co-opted by the banks and the unique statistical performance metrics used by TradingHub to solve the problem.

The amount of data from various sources: intelligence networks, traffic monitoring, social media, mobile phones, genomics, health etc) data now available for analysis has increased substantially in the last couple of years. However at the same time the requirements on the privacy of the underlying data have become more stringent requiring the need for algorithms to be developed that preserve the privacy of the underlying data while still extracting information with value (economic and otherwise). In this talk the algorithms and methodology being deployed by Privatar will be described.

Jason Mcfall (Privitar)

Privacy in the age of data science

The collection of vast data sets, and the availability huge compute power to analyse them, brings striking new threats to individual privacy. I'll talk through some of the risks and examples of privacy breaches, and survey some promising techniques for protecting data privacy by statistical means, and talk about why this is a hard problem to solve.

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15/04/2016 Richard Amos (UCL/UCLH)

Targeting cancer with proton beams: developments at UCL Hospital

Proton beam therapy (PBT) offers potential clinical advantages over conventional radiotherapy for cancer due to the physical characteristics of charged particle interaction. As protons traverse patient anatomy they lose energy, becoming more densely ionising as they approach their end-of-range, at which point they stop. This manifests into dose deposition as a function of depth that increases to a maximum, the Bragg peak, towards their end-of-range, with no dose beyond. By choosing proton beams of initial energy such that the Bragg peak region is delivered at the depth of the clinical target volume, the therapeutic dose can be realized with reduced dose to surrounding healthy tissue compared to that delivered by photons. Reduced dose to surrounding tissue offers the potential for reduced acute toxicity and secondary cancer risk. These potential clinical advantages have led to a rapid growth in availability of PBT worldwide in recent years and such capability will soon be available at UCL Hospital (UCLH) for NHS patients indicated for protons.

This presentation will describe contemporary PBT technology and practice with particular emphasis given to recent developments and the current status of the UCLH PBT project.

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08/04/2016 Nick Ryder (Oxford)

A SoliD seminar: The SoLid experiment: searching for neutrino oscillations within 10 m from a nuclear reactor

The SoLid collaboration aim to solve the reactor neutrino anomaly by determining whether it is due to oscillations to a new type of `sterile' neutrino. By measuring the anti-neutrino flux as a function of energy and distance between 5 and 10 m from a reactor core, 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 later this year.

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POSTPONED! now: 15/04/2016 Richard Amos (UCL/UCLH)

Targeting cancer with proton beams: developments at UCL Hospital

Proton beam therapy (PBT) offers potential clinical advantages over conventional radiotherapy for cancer due to the physical characteristics of charged particle interaction. As protons traverse patient anatomy they lose energy, becoming more densely ionising as they approach their end-of-range, at which point they stop. This manifests into dose deposition as a function of depth that increases to a maximum, the Bragg peak, towards their end-of-range, with no dose beyond. By choosing proton beams of initial energy such that the Bragg peak region is delivered at the depth of the clinical target volume, the therapeutic dose can be realized with reduced dose to surrounding healthy tissue compared to that delivered by photons. Reduced dose to surrounding tissue offers the potential for reduced acute toxicity and secondary cancer risk. These potential clinical advantages have led to a rapid growth in availability of PBT worldwide in recent years and such capability will soon be available at UCL Hospital (UCLH) for NHS patients indicated for protons.

This presentation will describe contemporary PBT technology and practice with particular emphasis given to recent developments and the current status of the UCLH PBT project.

11/03/2016: IOP Practise TALKS!

3rd years!

Exciting new results!

09/03/2016 Prof. Chris Done (Durham University)

XXVI SPREADBURY LECTURE: Black Holes - Science fact, fiction or fantasy ?

Black holes are a key plot device in science fiction and fantasy: wormholes through space and time ! In this lecture I'll separate out the fact from the fiction, and talk about how black holes went from a speculative extension of Einstein's gravity to a mainstream observational science via the development of rockets at the start of the space age.

26/02/2016: Chiara Casella (Geneva)

The SAFIR (Small Animal Fast Insert for mRi) experiment

SAFIR - Small Animal Fast Insert for mRi - is a non conventional positron emission tomography (PET) detector for fast and simultaneous hybrid PET/MRI imaging on small animals. The PET detector is designed specifically to be used inside the bore of a commercial 7T pre-clinical magnetic resonance scanner and with ultra short acquisition durations of the order of a few seconds, to enable quantitative dynamic studies of fast biological processes (e.g. blood perfusion and cerebral blood flow with 15O tracers). To compensate for the statistics losses due to the short scan durations, SAFIR will use up to 500 MBq injected activities, one order of magnitude increase with respect to state-of-the-art preclinical systems. Beside the clear MR compatibility, severe important challenges have to be met by the SAFIR detector, mainly in terms of spatial resolution, timing resolution and sensitivity, high number of readout channels, high rate capability per channel and huge data throughput. The detector will rely on matrices of L(Y)SO crystals, optically coupled to SiPM arrays and readout by existing fast readout ASICs. The seminar will describe the SAFIR goal, its concept and the status of the project, with particular emphasis on the characterization measurements of the detector components, including the recent high rate tests performed with different ASICs for the SiPM readout.

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19/02/2016 Uli Haisch (Oxford)

Indirect probes of Higgs effective theory

I review the existing indirect constraints on Wilson coefficients entering the Higgs effective theory. These limits are compared to the direct bounds obtained from LHC and LEP physics.

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12/02/2016 Katharina Bierwagen (MIT)

Measurement of inclusive W/Z production cross sections and CMS performance at sqrt(s)=13 TeV

Precise measurements of W and Z boson production provide an important test of the SM and can be used to further constrain the Parton Distribution Functions. The production of W and Z bosons is well understood in the SM and the clean signatures of the decay particles provide an ideal test bench for the commissioning of the electron, muon and missing energy reconstruction algorithms in the LHC environment. The first results of inclusive W and Z production cross section measurements in pp collisions at sqrt(s)=13 TeV with the CMS detector are presented.

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5/02/2016 Will Barter (CERN)

Recent LHCb measurements of electroweak boson production in Run-1

We present the latest LHCb measurements of forward Electroweak Boson Production using proton-proton collisions recorded in LHC Run-1. The seminar shall discuss measurements of the 8 TeV W & Z boson production cross-sections. These results make use of LHCb's excellent integrated luminosity determination to provide constraints on the parton distribution functions which describe the inner structure of the proton. These LHCb measurements probe a region of phase space at low Bjorken-x where the other LHC experiments have limited sensitivity. We also present measurements of cross-section ratios, and ratios of results in 7 TeV and 8 TeV proton-proton collisions. These results provide precision tests of the Standard Model.

The seminar shall also present a measurement of the forward-backward asymmetry (A_FB) in Z boson decays to two muons. This result allows for precision tests of the vector and axial-vector couplings of the Z boson, providing sensitivity to the effective weak mixing angle (sin^2(theta_W^eff)). The A_FB distribution visible in the LHCb acceptance is particularly sensitive to this angle, as the forward phase-space means that the initial state quark direction is better known than in the central region. This reduces theoretical uncertainties in extracting sin^2(theta_W^eff) from A_FB, and allows LHCb to make the currently most precise determination of sin^2(theta_W^eff) at the LHC.

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22/01/2016, Prof. Andre Schoening (Heidelberg)

The Mu3e Experiment

The Mu3e experiment will search for the Lepton Flavour violating decay mu^+ -> e^+ e^+ e^- with unprecedented sensitivity of 1 out of 10^16 muon decays. This process is heavily suppressed in the Standard Model and any signal would be a clear sign of new physics. The Mu3e experiment is based on the new HV-MAPS detector technology which allows to build ultra-light and fast high resolution pixel detectors.

15/01/2016 Ben Allanach (Cambridge)

Anatomy of the ATLAS diboson excess

I shall discuss some measurements from 8 TeV Run I LHC data that showed an excess over 2 sigma with respect to Standard Model expectations. In particular, we shall review the ATLAS di-boson excess, and show a couple of new physics scenarios that explain the excess. If there is time, I shall then discuss some excesses in CMS data: in a W_R search, in a di-leptoquark search and a new physics explanation that has implications for neutrinoless double beta decay.

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