IOP 2014 Joint HEPP & APP Group Meeting

Apr 7, 2014, 10:30 AM → Apr 9, 2014, 5:30 PM Europe/London

Windsor Building (Royal Holloway, University of London)

Jocelyn Monroe (MIT)

This is the joint meeting of the Institute of Physics High Energy Particle Physics and Astro Particle Physics groups. The meeting will take place at Royal Holloway, University of London starting Monday 7th April. Registration will be in the Windsor Building foyer from 10:30 am, and the conference will begin at 13:30. An STFC town meeting will follow on 9th April from 14:00 until 17:30 in the Boilerhouse.

Twitter hashtag : #IOPRHUL2014
 

The 40th Annual Bubble Chamber HEP football tournament will be held on Sunday 6th April.  For further details please see Bubble chamber tournament pages.

Registration will close 1st April 2014

Programme Summary iop2014_timetable.pdf

Mon, April 7

Registration

12:30 PM Lunch

Plenary 1: The Energy Frontier Programme

Convener: Session chair: Prof. Mark Lancaster

1 Welcome

Speaker: Prof. Paul Layzell, Principal

2 The Status of Standard Model Measurements at the LHC

A review of recent Standard Model results from the ATLAS and CMS experiments utilising data from Run I of the LHC is given. Results on jets, bosons plus jets, dibosons and top quark physics are discussed as well as observations of rare Standard Model processes.

Speaker: Dr Emily Nurse (University College London)

Slides LHCSMIOP2014.pdf

3 The Status of Beyond Standard Model Searches at the LHC

The search for physics beyond the Standard Model is a priority in the physics programme of the ATLAS and CMS collaborations. These searches cover a wide variety of experimental signatures and proposed models, ranging from, e.g., supersymmetry to heavy gauge bosons, extra dimensions and dark matter. In this talk the latest results obtained with up to 20/fb of data collected at 8 TeV centre-of-mass energy are presented and the implications on the parameter space of different new physics models are discussed.

Speaker: Dr Henning Flaecher (University of Bristol)

Slides IoP-RHUL-NewPhysics-Flaecher.pdf

4 The Status of the LHC Higgs Programme

The LHC Higgs programme has been spectacularly successful in discovering what has been variously called 'A new boson', 'a Higgs-like boson' and 'a Higgs boson' even while the machine was running well below design energy. But what do we really know about this particle? Why don't we just call it 'The Higgs boson', and will we ever do so? And what can it tell us about the remaining mysteries such as Dark Matter? Bill Murray has been closely involved with this search with the ATLAS experiment at CERN's LHC, and this talk contains the latest results on all these questions.

Speaker: Prof. William Murray (STFC/Warwick)

Slides royal-holloway.odp royal-holloway.pdf

5 125 GeV Higgs, Now What?

I will summarize the theoretical context for the search for the avatar of electroweak symmetry breaking, review what we have learned about H(125), and outline what we need to learn about the new particle. I will describe some of the questions raised and opportunities opened by the discovery of H(125), and how they influence our thinking about future accelerators. Finally, I will try to connect our studies of the Higgs sector with other explorations in particle physics.

Speaker: Dr Chris Quigg (Fermi National Accelerator Lab. (US))

Slides CQIOPHiggs14final.key.zip CQIOPHiggs14.pdf

3:50 PM Coffee

Plenary 2: The Cosmic Frontier Programme

Convener: Session chair: Prof. Dan Tovey

6 PLANCK: 2013 Results and Future Prospects

I review the main cosmology results from the 2013 Planck release. I will also discuss some developments since the original submission of the papers, and put the Planck results in the context of more recent results from the BICEP2 experiment.

Speaker: Dr Anthony Challinor

Slides 1_AChallinor.pdf

7 Gamma Ray Astronomy

Gamma-rays provide a unique probe of the non-thermal universe, allowing us to investigate a wide range of astroparticle physics and astronomy. At present, instruments such as the space-borne Fermi telescope and the ground-based HESS, MAGIC and VERITAS telescopes are providing us with a wealth of results, covering active galactic nuclei, supernova remnants, pulsars, gamma-ray bursts and many more object classes, as well as areas of fundamental physics. This talk will look at the methods used to detect gamma rays, consider a few recent results that are relevant to astroparticle physics and provide an introduction to the next-generation ground-based instrument, the Cherenkov Telescope Array (CTA).

Speaker: Prof. Paula Chadwick

Slides 2_PChadwick.pdf

8 Dark Matter Direct Detection

Physicists are still looking for what makes up most of our galaxy, and while there may be some hints, dark matter still has not been conclusively observed in the lab. I will present the current status of direct dark matter detection and the direction in which this research is headed.

Speaker: Dr James Nikkel

Slides JNIkkel_DM_IOP_2014.pdf

9 Cosmology: What Will the Next Big Discovery Be?

Cosmology has just had a major discovery: gravity waves from the early Universe. The Cosmic Microwave Background polarization experiment BICEP2 has announced detection of B-modes, which can be explained as the gravitational wave signature of inflation. I will discuss the significance of these ground-breaking results for cosmology. This discovery, if confirmed in future data sets, is a “smoking gun” for inflation. Further, when combined with data from the Planck satellite, thousands of inflation models have now been ruled out. Remaining simple models are few, and include natural inflation and quadratic potentials. Natural inflation uses “axions” as the inflaton, where the term “axion” is used loosely for a field with a flat potential as a result of a shift symmetry. That inflation could be so dramatically confirmed so quickly as a theory of the earliest Universe comes as a great surprise, and now the details of the inflaton even stand to be tested. A second major direction for the near future of cosmology is the identification of the dark matter of the Universe. The approach is three-pronged: the hunt for new physics at the Large Hadron Collider; underground laboratories searching for astrophysical WIMPs; and indirect detection of dark matter annihilation products. The excitement in the community is palpable: the searches are unearthing unexplained signals that may herald dark matter particles as the next big discovery in cosmology.

Speaker: Prof. Katherine Freese

Slides Freese_UK.pdf

6:30 PM Reception

Tue, April 8

Plenary 3: Flavour Physics

Convener: Session chair: Dr. Jonas Rademacker

10 Status of Quark Flavour Physics

With the successful start of the Large Hadron Collider at CERN quark flavour physics has entered a new era. Unprecedented samples of Beauty and charmed mesons and baryons have been collected by the LHCb experiment, which was built for this purpose, ATLAS and CMS also have large flavour physics data samples and the Tevatron and B-factory experiments continue to produce interesting results. Highlights include the measurements of CP violation in Bs mesons and the observation of the very rare decay Bs->mumu as well as precision measurements of Bs and charm mixing and B-hadron lifetimes. These results place strong constraints on the parameter space of many models of physics beyond the Standard Model.

Speaker: Prof. Franz Muheim

Slides iop-2014-muheim-final.pdf

11 Probing New Physics through Flavour Violation

Observation of charged lepton flavour violation (CLFV) would provide a clear signal for physics beyond the Standard Model. Selected recent experimental results and near-term prospects for the searches for CLFV processes are discussed. The processes considered include μ→e conversion, μ→eγ decay and lepton flavour violating decays of the charged kaons.

Speaker: Dr Evgueni Goudzovski

Slides goudzovski_080414.pdf

12 Electric Dipole Moments, Recent Results and Prospects

Measurement of a non-zero permanent electric dipole moment (EDM) would be clear evidence of a new source of CP violation outside of the quark mixing CKM matrix, and would be a possible signature of Supersymmetry. I will give an overview of current EDM experiments, including searches for atomic EDMs, recent improvements on the electron EDM upper bound measured in polar molecules, and the status of efforts to improve the neutron EDM limit. I will also discuss the Fermilab muon g-2 experiment and its prospects for measuring the muon EDM.

Speaker: Dr Clark Griffith

Slides GriffithIOP-EDMs.pdf

10:00 AM Coffee / Poster Session I

Plenary 4: The Neutrino Sector

Convener: Session chair: Prof. Christos Touramanis

13 Long Baseline Neutrino Oscillation Results from Current Experiments

In the last decade, neutrino experiments have provided overwhelming evidence for physics beyond the Standard Model. In this talk I will introduce the theory of neutrino oscillations and discuss current long-baseline neutrino oscillation experiments. Recent results from the T2K and MINOS experiments and prospects for the current generation of experiments will be presented.

Speaker: Dr Helen O'Keeffe

Slides okeeffe_iop2014.pdf

14 Neutrino Mass Searches with Beta Decay Experiments

Neutrinos are the second most abundant particle in the universe and yet one of the least understood. Their fundamental nature, whether they are their own antiparticle, is not yet known and the heaviest neutrino has a mass that we currently only known to within a range that spans about two orders of magnitude. In this talk I will review single beta decay experiments, which give us a model independent measure of neutrino mass based solely on kinematic parameters and energy conservation; and double beta decay experiments that allow us to probe the nature of the neutrino and the scale of absolute neutrino mass. Recent results from experiments and updates on the next generation of experiments, in particular SNO+ and SuperNEMO will be described.

Speaker: Dr Jeff Hartnell

Slides hartnellNuMassIoPRHUL2014.pdf

15 Neutrino Particle Astrophysics

Neutrino particle astrophysics is a frontier field at the crossroads of particle physics and astrophysics. Given the low fluxes of astrophysical neutrinos, gigantic detection volumes are necessary to detect the weakly interacting particles. The past twelve months have been an exciting time in the field on neutrino particle astrophysics, with the IceCube experiment claiming the first evidence for high energy extra-terrestrial neutrinos. If confirmed this evidence will be the first time since 1987 that neutrinos have been detected from outside of our solar system. Results from the current generation of neutrino particle astrophysics experiments will be presented, along with the prospects of imminent future experiments. Finally, the possibilities for utilising neutrino particle astrophysics detectors to measure neutrino oscillations will briefly be addressed.

Speaker: Dr Ryan Nichol

Slides neutrinoParticleAstrophysicsIOP2014.pdf

HEPP Group AGM

12:00 PM Lunch

Parallel 1A: Standard Model

Convener: Session chair: Dr. Veronique Boisvert

16 Measurement of the distribution of $\varphi^\star$ in events containing dimuon pairs with masses between 30 and 500 GeV in 10.4 fb$^{−1}$ of proton-antiproton collisions

The variable $\varphi^\star$ probes the same physical effects as the $Z/\gamma^\star$ boson transverse momentum, but is less susceptible to the effects of experimental resolution and efficiency. Using 10.4 fb$^{−1}$ of proton-antiproton collisions collected by the D0 detector at the Fermilab Tevatron, we measure the distribution of the variable $\varphi^\star$ in events containing dimuon pairs with masses between 30 and 500 GeV. The data are corrected for detector effects and presented in bins of dimuon rapidity and mass.

Speaker: Mr Xingguo Li (Manchester University)

Slides IOP.pdf

17 A measurement of the $\phi^{\star}$ angle in Drell-Yan di-lepton pairs

The $\phi_{\eta}^{\star}$ angle of Drell-Yan di-lepton pairs probes initial state gluon radiation and its definition relies only upon the well-measured lepton directions. The $\phi_{\eta}^{\star}$ distribution is sensitive to similar but complementary physics to the intermediate boson transverse momentum distribution. A measurement of the normalised $\phi_{\eta}^{\star}$ differential cross section around the Z-pole was made using the ATLAS detector at 7 TeV. In this talk progress towards an updated measurement using the full 8 TeV dataset is presented.

Speaker: Samuel Webb (University of Manchester (GB))

Slides 20140407_IOP_SamuelWebb_v8p3.pdf

18 Observation of electroweak Zjj production

Events with jets produced in association with a $Z$ boson in proton-proton collisions can be used to study distributions sensitive to the vector boson fusion (VBF) process at CERN's Large Hadron Collider. This process is interesting to study because of its similarity to the VBF production of a Higgs boson as well as its sensitivity to new physics via the WWZ triple gauge coupling. Evidence for electroweak $Zjj$ production beyond the $5\sigma$ level is presented using data collected by the ATLAS experiment in 2012. This constitutes the first observation of a process involving a VBF diagram. The detector-corrected cross sections measured in two fiducial regions are in excellent agreement with the Standard Model expectations.

Speaker: Christian Gutschow (University College London (UK))

Slides cg_iop-talk.pdf

19 Production of a Z Boson in association with b-jets measured with the ATLAS detector

This talk will present the first differential cross section measurements for the production of a Z boson produced in association with at least two b-jets. Data was collected using the ATLAS detector running at a centre of mass energy of 7 TeV during 2011. The analysis selects events with a leptonically decaying Z boson (to two electrons or two muons) produced in conjunction with two jets tagged as originating from a b-hadron. The results are compared to different predictions calculated at LO and NLO.

Speaker: Peter Robert Davison (University College London (UK))

Slides peterDavison_iop2014.pdf

20 QCD Estimation in V+jet Production at the LHC

One of the most challenges backgrounds to vector boson production in association with jets is that of QCD multijets. Current Monte Carlos struggle to model the background well and in adequate sample sizes. As a result data driven methods of estimation have been developed for use in precision analyses at the LHC. In this talk I will summarise the development of these methods in W+jet and R-jet (W/Z+jet) measurements at the LHC using the 2011 ATLAS dataset.

Speaker: Craig Anthony Sawyer (University of Oxford (GB))

Slides IOP2014_v3.pdf

21 Central exclusive production at LHCb: current analyses and future detectors

Central exclusive production (CEP) is a mechanism by which a final state is produced in isolation at central rapidity in an elastic collision. CEP provides a uniquely clean environment in which to carry out meson spectroscopy, and to search for evidence of phenomena such as gluon saturation. We introduce CEP and discuss the suitability of the LHCb detector to its study. LHCb measurements of central exclusive charmonium production using dimuon final states are presented, and ongoing analyses extending these measurements to hadronic final states discussed. The predominant background to CEP analyses at LHCb is contamination from inelastic production; HeRSCheL, a system of forward detectors to be installed to veto this background, is presented.

Speaker: Scott Stevenson (University of Oxford (GB))

Slides SS_20140408_IOP.pdf

22 Low Mu Run analysis on Measurement of the 2012 Inclusive Jet Cross Section in pp collisions at $\sqrt{s}=$8 TeV using the ATLAS detector

Jets are defined choosing the anti-kt algorithm with two radius parameters of 0.4 and 0.6. The inclusive double-differential cross section measurement at $\sqrt{s}=$8 TeV at 2012 is performed as a function of jet transverse momentum, in bins of jet rapidity. The data sample with no pile-up has been collected on low mu run for detector calibration and “clean” physics studies. Additionally, it provides to measure the low-$p_T$ . This talk will represent analysis of the inclusive jet double-differential cross-section on low mu run using function of the jet transverse momentum $p_T$ and jet rapidity y, covering a range of 20 $\leq p_T$ < 430 GeV and |y| < 4.4.

Speaker: Hilal Kucuk (University of London (GB))

Slides IOPPresentaion.pdf

23 B-tagging Calibration Bias Using Semileptonic Jets

The ATLAS experiment has several algorithms which are used to identify b-jets. In this talk I concentrate on the so-called “MV1” b-tagging algorithm, which includes information on displaced secondary vertices and the impact parameters of tracks as inputs into a Neural Network. To calibrate this b-tagging algorithm we test how well it works on b-jets in simulation and then compare this with its performance on b-jets in data. This calibration is performed on two types of b-jets, those that decay to a soft muon and neutrino, and those that do not. A ratio of performance in simulation and data is calculated to give a scale factor for each type of b-jet. A further comparison between the scale factors of the two types b-jet is provided in order to see if performing the calibration on b-jets that decay to a soft muon causes a bias. The calibration is performed on events with exactly two opposite sign leptons, two good jets, and large missing energy or large combined lepton plus jets transverse energy. This event selection provides a top pair enriched sample, which due to the large branching ratio of top quarks to b-quarks, also provides a sample enriched in b-jets.

Speaker: Joshuha Thomas-Wilsker (Royal Holloway, University of London (GB))

Slides 8_14h45_JTW_IOP-SL_BTaggingTalk_April_2014.pdf

24 Top pair differential cross-section measurements with respect to MET, HT and other global distributions at CMS

Measurements of the top-quark pair differential cross-section with respect to global distributions including missing transverse energy, scalar sum of jet transverse momenta, scalar sum of total event scalar sum, leptonic W boson transverse momentum and leptonic W boson transverse mass have been carried out on 19.7fb^-1 of data at 8TeV obtained from the CMS detector at the LHC. After a tight selection, signal and background templates are fitted to data and the resulting number of signal events is unfolded to the true distribution using the Singular Value Decomposition method. The differential cross-section calculation produces results which were found to be consistent with Monte Carlo simulation. This study complements a previous study with respect to missing transverse energy on 5.1fb^-1 of data at 7TeV. A combined measurement on 7TeV and 8TeV data is currently in progress and is expected to be completed shortly.

Speaker: Jeson Abe Jacob (University of Bristol (GB))

Slides IoP_2014.pdf

25 First Observation of the Associated Production of a Single Top Quark with a W Boson

The observation of the associated production of a single top quark and W boson using 12.2 fb$^{-1}$ of pp collisions at $\sqrt{s} = 8$ TeV with the CMS experiment is presented. A multivariate analysis based on kinematic variables was used to discriminate signal from the dominant ttbar background. The observed signal has a significance of 6.0$\sigma$ and a cross section of `$23.9^{+5.7}_{-5.6}$` pb. A cut and count cross check analysis was also carried out, finding a signal with a significance of 3.6$\sigma$ and a cross section of `$33.9^{+8.6}_{-8.6}$`. The results are in agreement with the standard model expectation of $22.2\pm 0.6\pm 1.4$ pb.

Speaker: Mr Duncan Leggat (University of Brunel)

Slides Leggat_Duncan.pdf

Parallel 1B: Flavour Physics 1

Convener: Session chair: Dr. Mitesh Patel

26 Search for the decay $\Lambda_b^0 \rightarrow \Lambda^0 \eta^{(\prime)}$ at LHCb

Decays involving $\eta$ and $\eta\prime$ mesons are particularly interesting to theorists, as they allow some insight into the relatively poorly understood topic of $\eta-\eta\prime$ mixing. This subject has been covered extensively using decays of $B$ and $B_s$ mesons, however, no equivalent processes have been observed in the baryonic sector. This talk outlines the search for the rare decay $\Lambda_b^0 \rightarrow \Lambda^0 \eta(\prime)$, using data recorded by the LHCb experiment. Results of the recent search in the data recorded during 2012 are presented, and the prospects for improvement using the full data set are outlined.

Speaker: James Mccarthy (University of Birmingham (GB))

Slides jmccarthy-iop2014.pdf

27 Measurement of the differential branching fraction of the rare decay $\Lambda_{b} \to pK\mu\mu$ at LHCb

Using the data from the LHCb experiment at CERN , the flavour structure of physics beyond standard model (SM) is probed using one of the rare B-decay channels, namely the $\Lambda_{b} \to pK\mu\mu$ decay. This decay occurs through a flavour changing neutral current process mediated by electroweak penguin and box diagrams in the SM. It is forbidden at the tree level and suppressed at the one-loop level by the GIM (Glashow–Iliopoulos–Maiani) mechanism. The first goal of the analysis is to use a dataset corresponding to 3fb-1 integrated luminosity collected by LHCb during 2011-12 to measure the differential branching fraction of this channel as function of the dimuon invariant mass squared. A multivariate event selection method was developed for this channel and the control channel $\Lambda_{b} \to pK J/\psi $. The general strategy of the analysis will be described. The features of the selection procedure and the steps involved in extracting the branching fraction will be presented. The systematic errors for this measurement also will be discussed.

Speaker: Mr Michael Kiss (STFC (RAL))

Slides IOP_presentation.pdf

28 The analysis of $B^0\rightarrow K^{{\star}0}\mu\mu$ decays at including S-wave contributions at LHCb

A status report for the analysis of $B^0\rightarrow K^{\star}(892)^{0} (\rightarrow K^+ \pi^-) \mu^+\mu^- $ decays at the LHCb detector at the LHC is presented. This process is the decay of a beauty meson to a vector meson final state and produces an angular distribution in the final state decay products. This angular distribution is highly sensitive to the contributions from Beyond Standard Model theories. There is a scalar $K^{{\star}0}$ component which enters into the analysis which has the effect of diluting the angular distribution. This so-called 'S-wave pollution' is addressed.

Speaker: Sam Cunliffe (Imperial College Sci., Tech. & Med. (GB))

Slides SCunliffe140407.pdf

29 Rare B decays in ATLAS: results and most recent updates on the 2012 analyses

Weak decays that are naturally suppressed in the Standard Model, such as processes with flavour-changing neutral-currents, are perfect for indirect searches of new physics. These decays allow us to investigate higher energy ranges with respect to direct searches thus representing a fundamental complementary tool. Results on the ATLAS search for the $B_s\rightarrow \mu^+\mu^-$ rare decay will be presented together with the most recent updates on the 2012 analysis that will be published soon. The ATLAS study of $B_d\rightarrow K^{\star}\mu^+\mu-$ is also reported where the parameters $A_{FB}$ and $F_L$ are extracted from the angular distribution of the final state.

Speaker: Cristiano Alpigiani

Slides IOP2014_CristianoAlpigiani_RareBsdecay_08042014.pdf

30 CP asymmetries in $B\rightarrow K^{(\star)}\mu\mu$ decays

Measurements of the direct $CP$ asymmetry, $A_{CP}$, and the $CP$ difference in the $\mu^+ \mu^-$ forward-backward asymmetry, $\Delta A_{FB}$, are made for the $B^{0} \rightarrow K^{\star{0}}\mu^+\mu^-$ and $B^+ \rightarrow K^+\mu^+\mu^-$ decay modes using $pp$ collision data corresponding to an integrated luminosity of 3$fb^{-1}$ collected by LHCb in 2011 and 2012. The respective control modes $B^0 \rightarrow J/\psi K^{\star{0}}$ and $B^+ \rightarrow J/\psi K^+$ are used to account for detection and production asymmetries. The measurements are made in several bins of $\mu^+ \mu^-$ invariant mass squared, $q^2$, vetoing the $\phi$ and charmonium resonance regions.

Speaker: Simon Robert Magee Wright (University of Cambridge (GB))

Slides SRMW_IOP_080414_v2.pdf

31 $B_{s}^{0} \rightarrow D_s^{(\ast)+} D_s^{(\ast)-}$ Decays in LHCb

The decay of a $B_{s}^{0}$ meson to two oppositely charged $D_{s}$ mesons is one that is postulated to be almost exclusively CP even. Measuring the properties of this decay can therefore give important information about the behaviour of the $B_{s}^{0}$ system. This presentation will focus on the measurement of the inclusive branching fraction of $B_{s}^{0} \rightarrow D_s^{(\ast)+} D_s^{(\ast)-}$, and will also consider other measurements made at LHCb using the same decay.

Speaker: Adrian Andrew Pritchard (University of Liverpool (GB))

Slides IOPPresentationFINAL.pdf

32 Search for $B_s^0 \to \phi \pi^+ \pi^-$ and $B_d^0 \to \phi \pi^+ \pi^-$ decays in LHCb

Using 3fb$^{-1}$ of $pp$ collision data collected at $\sqrt{s} = 7$ and 8 TeV by LHCb experiment in 2011 and 2012, first observation is made of the suppressed flavor changing neutral current (FCNC) decay mode $B_s^0 \to \phi (K^+ K^-) f_0(980) (\pi^+ \pi^-)$. In the $\pi^+ \pi^-$ invariant mass range below 1100 MeV/c$^2$, the branching ratio, using the reference decay $B_s^0 \to \phi \phi$, is measured to be: `$\mathcal{B}(B_s^0 \to \phi \pi^+ \pi^-) = [1.73 \pm 0.14 \pm 0.12 ^{+ 0.55}_{- 0.46}\, \mathcal{B}({B_s^0 \to \phi \phi})] \times 10^{-6} $` This presentation also focus on the measurement other decays with same final state and give some evidence for $B_s^0 \to \phi \rho^0(770)$ and $B_d^0 \to \phi \pi^+ \pi^-$ decays.

Speaker: Haofei Luo (University of Edinburgh (GB))

Slides IOP.pdf

33 Towards measurements of CKM parameters with loops and trees at LHCb

Elements of the Cabibbo-Kobayashi-Maskawa (CKM) matrix are accessible through a variety of processes. The Decay $B^+\!'\rightarrow D_s^+\phi$ is an annihilation diagram at tree level, which is sensitive to $V_{ub}$. While, contributions from the matrix element $V_{ts}$ are present in the loop level decays $B^+\!\rightarrow K^+\pi^+\pi^-\mu^+\mu^-$ and $B^+\!\rightarrow \phi K^+\mu^+\mu^-$. Results from LHCb for all these decays are presented.

Speaker: Mr Sam Hall (Imperial College London)

Slides iop_scph.pdf

34 A measurement of the CP-violation parameter $\gamma$ from $B^{\pm}\rightarrow [hh]_{D}K^{\pm}$ decays

Determination of the CKM angle $\gamma = \mbox{arg}[-V_{ud} V_{ub}^{\star}/(V_{cd} V_{cb}^{\star})]$ is one of the key goals of the LHCb experiment. The cleanest method to access this weak phase is through measurements of $\gamma$-sensitive observables in $B^{\pm} \rightarrow DK^{\pm}$ and $B^{\pm} \rightarrow D\pi^{\pm}$ decays. The largest interference and asymmetries, and thus the greatest sensitivities to $\gamma$, are expected in $B^{\pm} \rightarrow DK^{\pm}$ decays. The $D$ meson must be reconstructed in a final state accessible to both $D^{0}$ and $\bar{D}^{0}$ mesons, such that interference between the two amplitudes can provide access to phase information. Two-body $D$ meson decays into $K\pi$, $\pi K$, $KK$ and $\pi \pi$ provide such a platform. In this talk, current LHCb results and imminent prospects on the subject will be presented.

Speaker: Mr Donal Hill (University of Oxford, LHCb Experiment)

Slides IOP_2014_talk.pdf

3:15 PM End

Parallel 1C: SUSY

Convener: Session chair: Dr. Joanna Cole

35 Compressed and Split Spectra in Minimal SUSY SO(10)

The non-observation of supersymmetric signatures in searches at the Large Hadron Collider strongly constrains minimal supersymmetric models like the CMSSM. We explore the consequences on the SUSY particle spectrum in a minimal SO(10) with large D-terms and non-universal gaugino masses at the GUT scale. This changes the sparticle spectrum in a testable way and for example can sufficiently split the coloured and non-coloured sectors. The splitting provided by use of the SO(10) D-terms can be exploited to obtain light first generation sleptons or third generation squarks, the latter corresponding to a compressed spectrum scenario.

Speaker: Mr Tomas Gonzalo (UCL)

Slides IOP2014TomasGonzalo.pdf

36 Searching for supersymmetry with compressed mass spectra at CMS

Supersymmetry scenarios in which squarks, particularly in the third generation, are close in mass to the lightest supersymmetric particle are well motivated and offer a possibility for hidden, natural SUSY. Traditional searches are insensitive to these compressed mass spectra scenarios due to the very soft decay products. A search for light top squarks close in mass to the LSP at the CMS detector in 19.7 fb$^{-1}$ of pp collisions at $\sqrt{s}$= 8 TeV is presented using events with one high p$_{T}$ jet and a large transverse energy imbalance. By using monojet events to search for Initial State Radiation produced in association with top squarks, sensitivity to very compressed spectra is attained.

Speaker: Robyn Lucas (Imperial College Sci., Tech. & Med. (GB))

Slides IoP_CompressedSUSY.pdf

37 Supersymmetry searches in three lepton events at ATLAS

The ATLAS experiment at the Large Hadron Collider (LHC) has collected an unprecedented amount of data in the 3 years of data taking since its start. In this talk I will discuss the latest results from the Supersymmetry (SUSY) searches in events with three leptons (electron/muon/tau) in the final state. The search is performed on the full dataset collected by the experiment in 2012, at a centre-of-mass energy of 8 TeV. No evidence of SUSY is found. Observations are consistent with the Standard Model and exclusion limits are set on various SUSY models (pMSSM and simplified models). These results improve on previous searches performed at ATLAS in final states with only electrons and muons.

Speaker: Itzebelt Santoyo Castillo (University of Sussex (GB))

Slides ItzebeltSantoyo_IoP_2014.pdf

38 A search for supersymmetry using four or more leptons at ATLAS

A search for supersymmetry is presented, using four or more leptons with the ATLAS detector using $\sqrt{s} =$ 8 TeV data taken at the LHC during 2012. The motivations for this search. optimisation procedure and background estimation are outlined, and results presented for a number of RPC and RPV interpretations.

Speaker: Zara Jane Grout (University of Sussex (GB))

Slides 14_04_09_IOP.pdf

39 Search for strongly produced SUSY particles in events with zero leptons, jets and missing transverse energy with the ATLAS detector.

The strong production of Supersymmetric particles at the LHC offers one of the best current direct discovery prospects for Supersymmetry. This talk will focus on the event topologies of zero leptons 2-6 jets and missing transverse energy. Based on recent searches with the ATLAS detector on 8 TeV LHC data searching for squarks and gluinos.

Speaker: Gareth Thomas Fletcher (University of Sheffield (GB))

Slides IOP_talk_final_v2.pdf

40 Searching for SUSY in the Jets+MET channel with the AlphaT kinematic variable

A search for Supersymmetry in the all-hadronic channel using the CMS detector will be presented. The analysis looks for a jets + MET signature using the alphaT kinematic variable. Events are categorised in independent bins of jet multiplicity, b-tagged jet multiplicity, and HT, the scalar sum of jet pT. Interpretations are shown in a variety of Simplified Model Spectra, including both gluino-mediated and direct squark production. Some investigations into future analysis sensitivity for compressed spectra models will also be discussed.

Speaker: Christopher Lucas (University of Bristol (GB))

Slides iop_april_2014_v3.pdf

41 Searching for supersymmetry in events with large jet multiplicities using b-tagging and large-radius jets with 20 fb$^{−1}$ of ATLAS data

The Large Hadron Collider (LHC) ran in 2012 at the highest energy reached in a collider so far, allowing us to probe particle masses at the TeV scale. Strongly interacting particles at this mass scale are expected to decay in cascades, producing many jets from emissions of quarks and/or gluons and missing energy from weakly interacting daughters. This is the main target of the search for events with no leptons and large jet multiplicities, published recently by the ATLAS collaboration. The newest multi-jet analysis covers the full 2012 ATLAS data set, and has new features which improve sensitivity to various theoretical models. The results of the analysis are interpreted in various supersymmetric models, both R-parity conserving and violating. The new plans to measure the cross section of multijet events in 2012 data will also be briefly discussed.

Speaker: Mireia Crispin Ortuzar (University of Oxford (GB))

Slides mireiacrispin_IOP.v4.pdf

42 Searching for strongly produced SUSY with like-charge leptons at ATLAS

The most recent ATLAS analysis searching for two like-charge or three leptons places improved bounds on several strongly-produced supersymmetric models, both simplified and phenomenological. Whilst the targeted event signatures have very low backgrounds from the standard model, there are contributions from fake and charge-flipped leptons. I shall present an overview covering the data-driven methods that are used to estimate the contribution from these in our signal regions, and summarise the main results of this analysis.

Speaker: Thomas Gillam (University of Cambridge (GB))

Slides 2014-04-07_IOP_blinded.pdf

43 The CMSSM and NUHM1 after LHC Run 1

We show the results of global fits of the two constrained models of supersymmetry (SUSY): the constrained MSSM (cMSSM) and non-universal Higgs mass "1" (NUHM1). We take into account constraints from cosmology, electroweak precision observables, B-physics, Higgs physics and direct searches for SUSY at the LHC.

Speaker: Kees Jan De Vries (Imperial College Sci., Tech. & Med. (GB))

Slides Kees_Jan_de_Vries_IOP2014.pdf

3:15 PM End

Parallel 1D: Dark Matter I

Convener: Session chair: Dr. Chamkaur Ghag

44 Is there evidence for a Dark Matter signal in CoGeNT data?

The CoGeNT collaboration claim to have observed a signal of light Dark Matter scattering off nuclei in their detector, to a significance of approximately 2.5 sigma. I will critically assess these recent, and earlier, claims. I present a Bayesian analysis of the 1136 live days CoGeNT data, with particular focus on the removal of surface events through the use of nuisance parameters. I derive statistically robust confidence intervals using CoGeNT data, which fully incorporate this uncertainty, and show that the claims of signal in CoGeNT data are premature.

Speaker: Jonathan Davis (IPPP, Durham University)

Slides davis_iop_rhul.pdf

45 First results from the LUX dark matter experiment

A large number of astronomical and cosmological observations point towards the existence of an unknown dark component dominating the matter content of our Universe. The most compelling candidates for dark matter are Weakly Interacting Massive Particles (WIMPs), which may be detected in low background experiments located deep underground, searching for direct interactions of WIMPs with dedicated target materials. The Large Underground Xenon (LUX) experiment, operated in the Davis Campus of the SURF laboratory, USA, has announced results from its first science run in late 2013. From an exposure of 85 live days, having found no evidence of signal above expected background, LUX has set constraints on scalar WIMP-nucleon interactions above 7.6$\times$10$^{-46}$ cm$^{2}$ at 33 GeV/c$^{2}$ WIMP mass (90% CL). The sensitivity for light WIMPs (<10 GeV/c$^{2}$) is some 20 times higher than that of any other experiment, and the LUX result seriously challenges the interpretation of hints of signal claimed by other experiments as arising from low-mass WIMPs.

Speaker: Dr Lea Reichhart (University College London)

Slides IOP_04_2014_LUX_LR.pdf

46 Delayed Coincidence Analysis for Determining the 85Kr Background in LUX

$^{85}$Kr is an anthropogenic radioisotope which makes up a very small fraction of the Kr abundance in the atmosphere, and contributes to the background in double-phase xenon detectors searching for WIMP dark matter. It has a half-life of 10.8 years and decays predominantly via a $\beta^-$ decay with an endpoint of 687 keV. Commercially available xenon procured for LUX contained 130 ppb g/g Kr/Xe, which would lead to unacceptably high background. Before the start of the experiment this was reduced to 4±1 ppt g/g by chromatographic separation, as this noble gas is not removed further by the standard purification methods during operation. Current measurements of the $^{85}$Kr concentration use gas sampling assays to determine the overall Kr content with ppt sensitivity, and then assume a ratio of $^{85}$Kr/Kr as measured in the atmosphere. It is prudent to try to assess this background by determining the $^{85}$Kr content directly. This is possible due to a low branching ratio $\beta^-$ decay providing a delayed $\beta - \gamma$ coincidence with $T_{1/2}$ ~1 $\mu$s. We present results from a search of these rare decays performed on the LUX data used to derive the WIMP result previously published.

Speaker: Mr Adam Bailey (Imperial College)

Slides ABailey_Kr85Analysis_IOP.pdf

47 Multi Higgs doublet models

Multi Higgs-doublet models (NHDMs) are amongst the simplest extensions of the Standard Model, motivated for instance by Supersymmetric scenarios. I will discuss NHDMs with various symmetry groups which contain viable dark matter candidates, preserved by the remnant of the symmetry after EWSB. I will describe the dark matter phenomenology of these models and look into new Higgs decay channels offered by the extra doublets and their effect on the Standard Model Higgs couplings.

Speaker: Dr Venus Keus (University of Southampton)

Slides IOP-RHUL-2014.pdf

48 A DEAP Search for Dark Matter: An Overview of the DEAP-3600 Experiment

DEAP-3600 is a single-phase liquid Argon dark matter detector currently under construction at SNOLAB in Canada with first physics data expected in the summer, 2014. DEAP has been designed to achieve extremely low background rates, including those from 39Ar β decays, neutron scatters, and surface α contamination, with the goal of measuring the spin-independent WIMP-nucleon cross section down to 10$^{-46}$ cm$^{2}$ for a 100 GeV WIMP - a factor of 10 below current limits. Here an overview of the DEAP program will be presented including new results from DEAP-1 describing the background discrimination techniques and radon background measurements.

Speaker: Dr Joseph Walding (Royal Holloway, University of London)

Slides 5_walding.pdf

49 A DEAPer Search for Dark Matter: Getting Ready for Data

DEAP-3600 is a single phase liquid Argon dark matter detector based at SNOLab. Commissioning will start in May 2014 with first physics data is expected in the fall of 2014. This talk will present an overview of the analysis and calibration framework. In particular, some of the challenges found in characterising the photomultiplier tubes and their effect on timing based particle identification will be discussed.

Speaker: Alistair Butcher (R)

Slides AButcher_IOP_8Apr14.pdf

50 The long term future of direct detection Experiments and the Neutrino barrier.

The continuing search for dark matter will run into problems in the medium term future due to the background of neutrinos (especially from the Sun) which acts as a floor on the M-sigma plane beyond which it seems impossible to probe. We ask how far one can improve this situation using detailed energy, time and directional event information.

Speaker: Dr Malcolm Fairbairn (King's College London)

51 DMTPC Progress on Directional Dark Matter Detection

The Dark Matter Time Projection Chamber (DMTPC) project aims to detect the direction of dark matter-induced nuclear recoils, in order to correlate a candidate signal with the astrophysical dark matter wind associated with the Earth's motion through the galactic dark matter halo. This talk will discuss recent progress with emphasis on directionality.

Speaker: Mr Richard Eggleston (RHUL)

Slides REggleston_IOP2014_8.4.14.pdf

52 Simple steps to analyse direct detection experiments without halo uncertainties

Uncertainty in the local velocity distribution of dark matter is a key difficulty in the analysis of data from direct detection experiments. In my talk, I will propose a completely new approach for dealing with this uncertainty that does not involve any assumptions about astrophysics. By decomposing the dark matter velocity distribution into a sum of a large number of streams with different speeds and densities, we can find the velocity integral which best describes a given set of direct detection data for a hypothetical dark matter model. This method is conceptually simple, and numerically very efficient. I will discuss how to apply this method to estimate dark matter parameters independent of astrophysical uncertainties, choosing the ratio of proton to neutron couplings of dark matter as an interesting example.

Speaker: Felix Kahlhoefer (University of Oxford)

Slides 1D_Kahlhoefer.pdf

3:15 PM End

Parallel 1E: Rare/Precision Lepton Physics

Convener: Session chair: Dr. Simon Peeters

53 Search for Neutrinoless Double-β Decay of $\rm{^{100}Mo}$ in the final NEMO-3 dataset

The NEMO-3 detector, installed in the Modane underground laboratory, ran between February 2003 and January 2011. The NEMO-3 experiment employed a tracker and calorimeter detector technology to fully reconstruct the topology of the events generated in thin foils of active material. Thanks to its unique design, NEMO-3 studied the details of the Double-β decay in seven isotopes ($\rm{^{100}Mo}$, $\rm{^{82}Se}$, $\rm{^{116}Cd}$, $\rm{^{150}Nd}$, $\rm{^{96}Zr}$, $\rm{^{48}Ca}$ and $\rm{^{130}Te}$). We searched for neutrinoless Double-β (0νββ) decay of 100Mo, the largest sample of NEMO-3, using the complete set of collected data. With an exposure of 34.7 kg·y, no evidence for the 0νββ signal has been found, yielding the best limit for the light Majorana neutrino mass mechanism in this isotope. Taking into account nuclear model uncertainties this result is in the same sensitivity range as recently reported constraints on for the isotopes of $\rm{^{136}Xe}$ and $\rm{^{76}Ge}$. The same dataset is used to constrain other lepton number violating mechanisms of the 0νββ decay. In particular the most stringent constraints so far have been obtained for right-left symmetric and SUSY models. We describe this measurement.

Speaker: Dr Stefano Torre (UCL)

Slides Torre_NEMO3_IOP2014.pdf

54 Results of the NEMO-3 experiment and Low-radioactivity measurements for SuperNEMO with the BiPo detector

The main goal of the SuperNEMO collaboration is to search for neutrinoless double-$\beta$ decay. This would prove that the neutrino is a Majorana particle ($\nu$ = $\overline{\nu}$). Today the best lower limits on half-lives of this process are set around 10$^{24}$ - 10$^{26}$ years as obtained by the NEMO-3 experiment (for the 2$\beta$ isotope $^{100}$Mo) and other experiments. Several analyses are still ongoing, studying the different isotopes used for NEMO-3: $^{100}$Mo, $^{82}$Se, $^{96}$Zr, $^{150}$Nd, $^{48}$Ca, $^{116}$Cd. SuperNEMO is the next generation experiment based on the NEMO-3 tracker-calorimeter detection principle. Given the rareness of the processes studied here, the lowest possible levels of background are required. These levels are too low to be reached using non destructive techniques such as High Purity Germanium detectors. A new type of detector has been constructed, BiPo-3, targeting activities lower than can be achieved through $\gamma$ spectrometry. This detector is designed to measure contaminations in $^{208}$Tl (around few $\mu$Bq/kg) and $^{214}$Bi (few dozen $\mu$Bq/kg) in thin materials. BiPo-3 has been fully operational at the Laboratorio Subterr$\acute{a}$neo de Canfranc (LSC, Spain) since January, 2013. The NEMO-3 experiment, the status of the current analysis on $^{96}$Zr and the results on $^{100}$Mo and $^{82}$Se will be presented. The BiPo-3 detector will be described along with the radiopurity requirements for SuperNEMO source foils measurements.

Speaker: Mr Guillaume Eurin (University College London (UK))

Slides IoP_NEMO.pdf

55 Status of the SuperNEMO experiment

The SuperNEMO experiment aims to search for neutrinoless double beta decay. If observed, this would show that the neutrino is its own antiparticle and be the first evidence for total lepton number violation. With 100 kg of source, a half-life sensitivity of order $10^{26}$ years (effective neutrino mass sensitivity down to 50 meV) can be achieved. The experimental techniques are similar to the predecessor NEMO-3 experiment, with a tracker-calorimeter setup. Decay electrons from a source foil pass through a magnetised tracker, aiding in particle identification, and the calorimeter measures their energy. The setup is able to measure the angular distribution of the decay products, which can aid in determining the underlying physical process behind the lepton number violation if observed. The unique design with separation of source and detector also allows the study of different isotopes concurrently. To prove the challenging radiopurity requirements of the experiment are achievable, a Demonstrator module is currently under construction and will start taking data next year. The current status of the Demonstrator production will be presented.

Speaker: Pawel Guzowski (University of Manchester)

Slides pguzowski_iop_talk_2014.pdf

56 The SNO+ Experiment

A summary of the current status of the SNO+ experiment. The SNO+ experiment located in the SNOLAB facility in Sudbury, Ontario, Canada will primarily search for neutrinoless double beta decay by deploying Te130 into a kTonne of liquid scintillator. The experiment will additionally study solar, geo, supernova (if one occurs) and reactor neutrinos as well as nucleon decay in a separate water phase.

Speaker: Dr Philip Jones (QMUL)

Slides IoP2014.pdf

57 Developing criteria for SNO+ Data Quality and Run Selection

The multi-purpose SNO+ detector, part of SNOLAB, is currently being filled with ultra-pure water, marking the first step before the addition of liquid scintillator and then Tellurium. While the level of water in the detector rises, the level of activity in preparation for commissioning is accordingly steadily increasing. Recent periods of continuous operation—each lasting of order two weeks—produced a wealth of “dark” data, which has already proved invaluable for testing critical systems. After presenting an overview of the SNO+ experiment, this presentation will focus on Front-end Calibrations, particularly Data Quality and Run Selection, based on analysis of the current “dark” data. An account of how the Data Quality Criteria were developed, is presented, followed by a discussion of how they are being verified and tuned using the recent SNO+ data.

Speaker: Ashley Back (Queen Mary, University of London)

Slides ARBackIOP.pdf

58 The FNAL muon g-2 experiment

The 2004 measurement of the muon’s anomalous magnetic moment by the E821 experiment at Brookhaven is the second most cited paper in experimental particle physics behind the observation of neutrino oscillations. This measured value differs by 3.6σ from the Standard Model (SM) prediction. This may be indicative of new physics beyond the SM or a statistical fluctuation. In this talk I will outline the role the UK is playing in a new experiment, E989, at FNAL, that will measure the muon’s anomalous magnetic moment with a precision four times better than the E821 experiment and so resolve this issue. This precision is sufficient to establish evidence for new physics beyond the SM at more than 5σ should the present anomaly be confirmed.

Speaker: Mark Lancaster (University College London (UK))

59 Magnetometry standard for the muon g−2 experiment

A key requirement of the g−2 experiment, aiming to measure the muon anomalous magnetic dipole moment to 0.14ppm, is to monitor the magnitude of the magnetic field around the storage ring to 0.07ppm. This will be done with several hundred proton NMR magnetometers. These must all be calibrated against a standard magnetometer, to account for the ~0.1ppm shifts of individual probes due to the magnetic properties of the materials. We are developing a 3He magnetometer to provide an independent check of the standard calibration probe used for the Brookhaven g−2 experiment, which was based on a spherical water sample.

Speaker: Dr Sam Henry (University of Oxford)

Slides g2_magnet_IOP_SH_v2.pdf

60 A Search for Muon to Electron Conversion with COMET

I will describe the COMET experiment, which will search for muon to electron conversion in aluminium, and I will also present some of the work I have done for it.

Speaker: Andrew Edmonds (UCL)

Slides IoP_COMET.pdf

61 SQUID Magnetometry for Neutron EDM Experiments

Neutron electric dipole moment (nEDM) experiments require precision magnetometry to correct for systematic effects due to magnetic field fluctuations. I discuss the options for such magnetometers and present details of a 12-SQUID magnetometry system constructed for use in a cryogenic nEDM experiment. This has been developed to operate in 0.5 K superfluid helium and installed and tested in apparatus at the Institut Laue Langevin, Grenoble. The system is designed to track fields at the 0.1 pT level, consistent with a proposed experimental limit on an nEDM of $d_n \sim 10^{-27}\,e$cm.

Speaker: Ms Amy Cottle (University of Oxford)

Slides IOPTalk.pdf

62 A prototype atomic interferometer for fundamental physics

Atom interferometers are precision instruments, currently capable of measuring forces an unprecedented precision, with this precision becoming more precise with the development of new techniques. Using atomic interferometers, a parameter search can be made to investigate the dark contents of the vacuum and shed some light on fundamental physics questions such as "What is the nature of dark energy?". A prototype device is currently under construction at the University of Liverpool, and this talk will discuss the atom interferometer concept and the construction progress.

Speaker: Oliver Burrow (University of Liverpool)

Slides IOP_RH_OliverBurow.pdf

3:30 PM Coffee

Parallel 2A: Detectors

Convener: Session chair: Dr. Antonin Vacheret

63 A software framework and toolkit for developing simulations of 2D pixel detectors

X-CSIT (X-ray Camera SImulation Toolkit) is a software framework and toolkit for creating simulations of 2D X-ray pixel detectors. As a toolkit, X-CSIT is designed to be highly modular and adaptable to the wide variety and variations found in X-ray cameras. X-CSIT is under development at UCL for European XFEL, and will be used to create simulations of the three bespoke 2D detectors at European XFEL, AGIPD, LPD and DSSC. These simulations and X-CSIT will be integrated into the European XFEL software framework, Karabo, and through that be available to users to aid with planning of experiments and analysis of data. In addition X-CSIT will be released standalone publicly for other users, collaborations and groups to create simulations of their own detectors.

Speaker: Mr Ashley Joy (UCL)

Slides Slides

64 3D Silicon and 3D Diamond detectors for future upgrades of LHC experiments

I present an overview on the development of cutting edge 3D diamond and 3D silicon detectors for future upgrades of LHC experiments, with a focus on work done in Manchester. A 3D geometry and its beneficial effects on a detectors radiation tolerance, signal speed and power dissipation have been extensively studied in silicon. As such, 3D silicon is a proven technology; it is included in the current phase 0 upgrade of ATLAS, and is a serious candidate for innermost layer tracking detectors at the High Luminosity LHC. Following the success of silicon, we are applying the concept of a 3D geometry to other semiconductor materials, specifically diamond, in the hope of creating a super radiation tolerant detector.

Speaker: Iain Haughton (University of Manchester (GB))

Slides

• IOPConfTalk.pdf
• IOPConfTalk.pptx
• IOPConfTalk.pptx

65 Characterisation of ATLAS planar pixel modules for ATLAS Upgrade

Planar pixel sensors based on the Front-End-I4 (FE-I4) read-out developed for the Insertible b-Layer (IBL) are being characterised in laboratory tests and in test beams. Systematic tests are being performed to judge the performance of these sensors and read-out chips. Multiple geometries of pixel sensor have been developed. Laboratory tests include threshold and time-over-threshold tuning as well as source scans to determine bump-bond yield from the module-building process. Both data acquisition systems USBPix, developed at Bonn, and the RCE system, developed at SLAC, have been used to perform characterisations in the laboratory. A selection of modules have been irradiated to fluences expected after 10 years running at 14TeV in the pixel barrel of ATLAS. Both irradiated and un-irradiated modules have been tested in test beams in CERN (80GeV pions) and DESY (4GeV electrons) in conjunction with the EUTelescope. The data from the test beams is being reconstructed and analysed in order to determine efficiency and resolution of the sensors.

Speaker: Kate Doonan (University of Glasgow (GB))

Slides kdoonan_IOP2014_ATLAS-Pixels.pdf kdoonan_IOP2014_ATLAS-Pixels.pptx

66 The CBC2 ASIC for 2S Modules at HL-LHC

I will present the front-end readout ASIC for the High-Luminosity Upgrade of the CMS Strip Tracker. The CMS Binary Chip 2 is a full-scale prototype ASIC with 254 channels, capable of identifying high transverse-momentum trigger primitives by correlating hits between the two closely-spaced silicon strip sensors of the Tracker module. I will present the performance of the chip, together with the plans for its final version and an overview of current R&D activities, which include a first beam test of a prototype module and preliminary irradiation testing.

Speaker: Davide Braga (RAL/STFC)

Slides CBC2_IOP2014_comp.pdf CBC2_IOP2014_comp.pptx

67 TORCH - a Cherenkov based Time-of-Flight Detetor

TORCH (Time Of internally Reflected CHerenkov radiation) is an innovative time-of-flight system designed to provide particle identification over large areas up to a momentum of 10 GeV/c. Cherenkov photons emitted within a 1 cm thick quartz radiator are propagated by internal reflection and imaged on to an array of Micro-Channel Plate photomultiplier tubes (MCPs). Performing 3-$\sigma$ pion/kaon separation at the limits of this momentum regime requires a time-of-flight resolution per track of 10-15 ps, over a ~10m flight path. With ~30 detected photons per track the required single-photon time resolution is ~70 ps. This presentation will discuss the development of the TORCH R&D program and present an outline for future work.

Speaker: Euan Niall Cowie (University of Bristol (GB))

Slides Euan Niall Cowie - TORCH: a Cherenkov based Time-of-Flight detector.

68 LHCb's future vertex detector

A major upgrade of the LHCb experiment is planned to start taking data in 2020. The LHCb Vertex Locator will be replaced by a new and highly novel detector. It will be based on radiation hard hybrid pixel sensors, with a pixel dimension of $55\times{}55\,{\mu{}}\text{m}$, cooled using $\text{CO}_2$ flowing through microchannels integrated into the silicon. During operation, the sensors will be only $5\,\text{mm}$ from the LHC beams. The general design, optimisation process and expected performance of this Vertex Locator will be described.

Speaker: Thomas Bird (University of Manchester (GB))

Slides TBirdVeloIOP.pdf

69 Sensor R&D for the stable operation of the LZ detector

Maintaining stable operating conditions is of utmost importance in any dark matter detector. The LZ detector will be the largest two-phase liquid xenon detector ever constructed and as such will require unsurpassed levels of monitoring. This talk will discuss R&D efforts to this end in the UK and will cover the development of position, liquid level and piezo-electric bubble sensors and of loop antennae for the detection of electric discharges.

Speaker: Paul Scovell (University of Oxford)

Slides PRS_IoP.pdf

70 High voltage delivery in LZ

LUX-ZEPLIN (LZ) is a next-generation direct dark matter search experiment based on a 7-tonne double-phase xenon detector. The large active xenon target brings many benefits, namely outstanding self-shielding of an inner fiducial volume, but also some practical challenges, in particular the need to provide high voltages to sustain the required electric fields. LZ is undertaking a comprehensive R&D programme to address the different aspects involved, such as the development of feedthroughs with a design voltage of 200 kV, aiming for an operating voltage of 100 kV at the cathode electrode. Intriguing phenomenology has been emerging from previous attempts to sustain strong electric fields in ultrapure liquid noble gases, and our programme addresses the physics processes involved at a microscopic level too. Our understanding of the HV breakdown mechanisms will inform the engineering solutions and procedures adopted in LZ. In particular, a test system is being operated at Imperial College to study high field phenomena at the surface of thin metal wires, one of the most challenging aspects of HV delivery to noble liquids.

Speaker: Dr Alfredo Tomas Alquezar (Imperial College London)

Slides IoP2014_HVinLZ_ATomas.pdf

71 The SoLid Experiment

Oscillation to sterile neutrinos is considered as a possible explanation for the reactor and Gallium neutrino anomalies, which both measured a deficit of neutrinos at short distances from the respective sources. The SoLid experiment will test this hypothesis by measuring neutrino energy spectra between 6-8 m from a reactor core and looking for distortions in the spectra at different distances caused by any oscillation. The experiment uses a novel detector design built up from PVT scintillator cubes with one face covered by a mixture of lithium-6 fluoride and silver activated zinc sulphide. Electron anti-neutrinos from the reactor are reconstructed from the detection of the positron and neutron from Inverse Beta Decay (IBD) events. The positrons are detected in the PVT scintillator, while the neutrons thermalise and then react with the lithium-6, producing particles which are detected in the zinc sulphide scintillator. Due to the properties of the two scintillators the positron and neutron signals can easily be distinguished. The highly segmented detector means that precision timing and location of the detected neutron (relative to the prompt positron signal) can be used in identifying IBD events, enabling a strong suppression of an accidental combination of the background neutron signal with the high rate of gamma rays coming from the reactor. The experiment will be performed at the BR2 research reactor at SCK-CEN in Mol, Belgium. A small (8 kg) prototype detector was constructed in 2013 and has been deployed at the experimental site during a number of reactor on/off cycles. The prototype detector is being used to understand the background signals expected for the experiment and to measure the detector response so that the full scale detector's design can be optimised. In this talk the motivation for the experiment will be reviewed, the experimental set-up will be introduced and the detection principle will be explained using data collected by the prototype.

Speaker: Nick Ryder (University of Oxford (GB))

Slides ryder-solid-iop.pdf

72 Detecting Special Nuclear Material With Muon Scattering Tomography

We present a novel approach to the detection of special nuclear material using cosmic rays. Muon Scattering Tomography (MST) is a method for using cosmic muons to scan cargo con- tainers and vehicles for special nuclear material. Cosmic muons are abundant, highly penetrating, not harmful for organic tissue, cannot be screened against, and can easily be detected, which makes them highly suited to the use of cargo scanning. Muons undergo multiple Coulomb scattering when passing through material, and the amount of scattering is roughly proportional to the square of the atomic number Z of the material. By reconstructing incoming and outgoing tracks, we can obtain variables to identify high-Z material. In a real life application, this has to happen on a timescale of 1 min and thus with small numbers of muons. We have built a detector system using resistive plate chambers (RPCs): 12 layers of RPCs allow for the readout of 6 x and 6 y positions, by which we can reconstruct incoming and outgoing tracks. We also present the performance of an algorithm by which we separate high-Z targets from low-Z background, both for real data from our prototype setup and for MC simulation of a cargo container-sized setup.

Speaker: Mr Christian Thomay (University of Bristol)

Slides CThomaytalk_iop2014.pdf

Parallel 2B: Flavour Physics II

Convener: Session chair: Dr. Marcella Bona

73 Search for CP violation in $B\rightarrow DK$, $D\rightarrow hh\pi^0$ decays at LHCb

Charged $B$ decays of the form $B^\pm \rightarrow DK^\pm$ (where $D$ represents either a $D^0$ or a $\bar{D^0}$) are powerful tools in the measurement of the $CP$-violating CKM angle $\gamma$. Channels where the $D$ decays to a final state involving a $\pi^0$, such as $D \rightarrow \pi^\pm K^\mp \pi^0$, $D \rightarrow \pi^\pm \pi^\mp \pi^0$ and $D \rightarrow K^\pm K^\mp \pi^0$ are promising modes for these studies, but present challenges in the fierce environment of the LHC. In this talk I shall demonstrate that the excellent performance of the LHCb detector allows for high purity samples of these decay modes to be isolated, and consequently, their use in an ongoing $CP$-violation analysis using 3.0 fb$^{-1}$ of data.

Speaker: Nazim Hussain (University of Oxford (GB))

Slides NH_IOP_Final.pdf

74 Dalitz plot analysis of $B_s\rightarrow D^0K\pi$

Dalitz plot analyses of $B^0_{(s)}\rightarrow D^0K\pi$ are interesting for multiple reasons. The decay $B^0\rightarrow D^0K\pi$ can be used to make a measurement of the CKM angle $\gamma$. The $B^0_s$ decay is interesting both as a potential background to the $\gamma$ measurement but also to obtain branching fraction measurements for the various two body decays that contribute to $B^0_s\rightarrow D^0K\pi$ and to investigate $D_s^{**}$ spectroscopy. I present preliminary results from a Dalitz plot analysis of $B^0_s\rightarrow D^0K\pi$ based on data from the LHCb experiment.

Speaker: Daniel Charles Craik (University of Warwick (GB))

Slides 20140408_IOP_B2DKpi_DanielCraik_v2.pdf

75 Charmless three body decays at LHCb

The study of charmless three body decays with final states including a $K^{0}$ meson has an extensive number of application. In this talk a review of the recent and ongoing analyses at LHCb will be reported. First, a search for previously unobserved decays of beauty baryons to the final states `$K^{0}_{\mathrm{S}}p\pi^{-}$` and `$K^{0}_{\mathrm{S}}pK^{-}$` is reported. The analysis is based on a data sample corresponding to an integrated luminosity of $1.0$ fb$^{-1}$ of pp collisions. The `$\Lambda^{0}_{b} \rightarrow K^{0}_{\mathrm{S}}p\pi^{-}$` decay is observed for the first time with a significance of 8.6$\,\sigma$, and a measurement is made of the $CP$ asymmetry, which is consistent with zero. Moreover, with the recent measurement of branching fractions of the `$B^{0}_{(s)} \rightarrow K^{0}_{\mathrm{S}}h^{+}h^{‘-}$` decay modes ($h^{(′)} = \pi, K$) with 2011 data, a number of developments have been performed towards the analysis of the full dataset. In particular, the details considering a time integrated untagged Dalitz plot analysis will be described.

Speaker: Rafael Silva Coutinho (University of Warwick (GB))

Slides Talk.pdf

76 Search for the two-body charmless baryonic $B$-decays $B^{0} \to p \bar{p}$ and $B_{s}^{0} \to p \bar{p}$ at LHCb

Results from the recently published search for the rare decays $ {B^0}\to p\bar{p} $ and $ B_s^0\to p\bar{p} $ carried out using 0.92 fb$^{-1}$ of 7 TeV proton-proton collisions collected by the LHCb experiment in 2011 will be presented ([arXiv:1308.0961 [hep-ex]][1]). The talk covers the physics motivation for the analysis and the tensions between existing theoretical predictions of the branching fractions, the selection criteria applied and a description of the Feldman-Cousins statistical analysis methods used to extract the branching fractions for the two decay channels. The status of an updated $B^{0} \to p \bar{p}$ and $B_{s}^{0} \to p \bar{p}$ analysis on the combined 2011 and 2012 data sets will also be presented as will details of a new analysis searching for the decay $B^{+} \to p \bar{\Lambda}$. [1]: http://arxiv.org/abs/1308.0961

Speaker: John Beddow (University of Glasgow (GB))

Slides JBeddow-IOP2014.pdf

77 Time-dependent measurements of CP violation in charm

The method for the measurement of two charm CP violating observables, $A_{\Gamma}$ and $y_{CP}$, is presented. The results for $A_{\Gamma}$ are shown to be the most precise to date.

Speaker: Mark Elliot Smith (University of Manchester (GB))

Slides Mark_Smith_IOP4.pdf

78 D mixing in multi-body decays

Although mixing in neutral K and B systems has long been established, mixing in neutral D mesons has only recently been observed. In fact, in 2012 LHCb published the first single observation of D mixing in $D^{0} \to K^{-}\pi^{+}$ decays. LHCb has now collected enough data to study D mixing in multi-body D decays such as $D^{0} \to K^{+}\pi^{-}\pi^{0}$ and $D^{0} \to K^{+}\pi^{-}\pi^{+}\pi^{-}$. Whilst these decay modes do not necessarily provide as much sensitivity to mixing, they provide us with another exciting opportunity. D mixing results in a time dependent superposition of $D^{0}$ and $\bar{D}^{0}$ states. This superposition is defined by the dimensionless mixing parameters $x$ and $y$. With knowledge of $x$ and $y$ from other analyses, we can now use D mixing to investigate the interference effects betweek $D^{0}$ and $\bar{D}^{0}$ amplitudes, including information on their relative phase. In particular, one can constrain the coherence factor, $R_{K\pi\pi\pi}$, and average strong phase difference $\delta_{ K \pi\pi\pi }$. These two parameters provide important input to extracting the CP violating phase $\gamma$ in $B^{\pm}\to DK^{\pm}$ decays.

Speaker: Samuel Thomas Harnew (University of Bristol (GB))

Slides SamHarnew.pdf

79 Crystal collimation for LHC

One of the main challenges at the CERN Large Hadron Collider (LHC) is to handle the unprecedented stored beam energies that are expected to be up to 360MJ with 7~TeV beams at 25~ns bunch spacing. This may increase to 500~MJ in the LHC High Luminosity upgrade project (HL-LHC). A complex collimation system, able to intercept and to absorb beam halo particles efficiently is used to minimize losses onto superconducting magnets that could cause them to quench. The present collimation system consists of about 50 two-sided collimators per beam, which are precisely placed at the edge of the transverse beam envelope in a four-stage hierarchy. This system has worked very well during LHC Run~1 at 3.5 and 4 TeV, essentially achieving the design cleaning inefficiency of about $10^{-5}$. However, this will be not enough for the future operational challenges of the LHC and its upgrades. A very promising technology to overcome the limitations of the present system is based on silicon crystals instead of amorphous primary collimators. A bent crystal can be used as a primary collimator, using the principle of channeling by the atomic planes, to deflect halo particles onto a heavy absorber. Experimental tests have been carried out over the last 4 years at the CERN Super Proton Synchrotron (SPS), showing the feasibility of beam cleaning using channeling. Application in the LHC requires detailed simulations and the execution of beam tests in the LHC itself, which are foreseen in 2015. Extensive design studies have been carried out to integrate suitable crystals into the collimation system layout, and samples are presently being installed in the LHC. According to simulations, this should lead to an improvement of up to a factor 10 in collimation cleaning thanks to efficient steering of halo particles onto a single absorber. The design of the crystal layout for the first LHC beam tests and the state of simulation tools for crystal collimation studies, bench-marked against the SPS beam measurements, will be discussed.

Speaker: Daniele Mirarchi (Imperial College Sci., Tech. & Med. (GB))

Slides IoP2014_DM.pdf IoP2014_DM.pptx

80 Investigating the Microbunching Instability at Diamond Light Source

Diamond Light Source is a third generation synchrotron facility dedicated to producing radiation of outstanding brightness. Above a threshold current, the electron bunches are susceptible to a phenomenon known as the microbunching instability. The key feature of this instability is the emission of coherent radiation bursts, which have wavelengths of the order of the bunch length and smaller. The bursting at the threshold is emitted quasi-periodically, however increasing to a higher current results in the bursting to appear random in nature. The high frequencies involved in these emissions make characterizing the phenomenon a challenging task. A setup at Diamond has been built, dedicated to the investigation of this phenomenon. An overview of the project will be presented, including a description of the instability, the experimental setup, and recent results.

Speaker: Mr William Shields (Royal Holloway, University of London)

Slides WILLIAM_SHIELDS_IOP_2014.pdf WILLIAM_SHIELDS_IOP_2014.pptx

81 The AWAKE experiment beam-plasma interaction simulations

Speaker: Scott Mandry (University College London, Max-Planck-Institut für Physik)

Slides iop-talk.ppt

82 Muon tomography to monitor carbon sequestration

Speaker: Sam Telfer (The University of Sheffield)

Slides telfer_iop_rhul.pdf

Parallel 2C: Higgs

Convener: Session chair: Dr. Jon Hays

83 Evidence for Higgs Boson Decays to the $\tau\tau$ Final State with the ATLAS Detector

I will present results of a search for the 125 GeV Higgs boson decaying to a pair of tau leptons. The dataset used is 20.3fb$^{-1}$ of proton-proton collision recorded by the ATLAS detector at a centre of mass energy of 8 TeV. The observed (expected) deviation from the background only hypothesis corresponds to a significance of 4.1 (3.2) standard deviations. The measured signal strength is $\mu = 1.4^{+0.5}_{-0.4}$. This constitutes evidence for the existence of Higgs to $\tau\tau$ decays and is consistent with the Standard Model expectation of a Higgs Boson with mass 125 GeV.

Speaker: Carl Jeske (University of Warwick)

Slides carl_iop_higgs_tautau.pdf

84 ATLAS results on the Higgs boson properties in the decay channel $H\rightarrow ZZ\rightarrow 4\ell$

This contribution will review the latest ATLAS results on the properties of the Higgs boson in the decay channel $H\rightarrow ZZ\rightarrow 4\ell$ using approximately 25 fb-1 of pp collision data collected during the LHC Run1 at 7 TeV and 8 TeV. The measurements of the mass and the couplings of the newly discovered boson are presented together with the spin-parity analysis results.

Speaker: Ludovica Aperio Bella (University of Birmingham (GB))

Slides H4l_IOP_2013_LAB.pdf

85 Overview of 0-Lepton $Z(\nu\nu) + H(b\bar{b})$ Analysis and b-tagging MC Calibration

Since its discovery a large effort has been made to improve analyses and confirm the properties of the Higgs Boson. At a mass of 125 GeV Higgs to $b\bar{b}$ is the dominant decay mode, however large QCD backgrounds prevent direct analysis, instead an analysis of Higgs to $b\bar{b}$ is considered where the Higgs is produced in association with a Vector Boson ($W$/$Z$). A brief overview of this analysis will be presented with particular focus on the $Z$($\nu\nu$) $H$($b\bar{b}$) channel. Common to other analyses where high $p_T$ jets are required flavour tagging is a dominant systematic in this analysis. Details of Monte Carlo studies helping to reduce these systematics are also presented.

Speaker: Matthew Ian Jackson (University of Liverpool (GB))

Slides IoP.pdf

86 The matrix element method in the search for dileptonic ttH(H$\to$bb)

With the expected reach of ttH(H$\to$bb) not quite approaching Standard Model sensitivity, it is important to squeeze as much information out of the data as possible. The matrix element method calculates the probability of an event coming from signal (ttH) and background (ttbb) decay process by calculating the most likely kinematics of the hard scattering partons and comparing with the kinematics of the reconstructed objects. This talk will focus on ttH physics and the theory, implementation and results of the matrix element method in this channel.

Speaker: Ian Allan Connelly (Royal Holloway, University of London)

Slides IOP_IanConnelly_MEM_ttH.pdf

87 Novel Techniques to improve the Invariant Dijet Mass Reconstruction in the Standard Model Higgs boson resonance search $H\rightarrow b\bar{b}$ in association with a W/Z boson using the ATLAS detector

An updated direct search for a Standard Model Higgs boson decaying into pairs of $b$ quarks in association with a W or Z boson using the ATLAS detector at the LHC is presented. The search is performed in the three decay modes $ZH\rightarrow\nu\nu b\bar{b}$, $WH\rightarrow\ell\nu b\bar{b}$ and $ZH\rightarrow\ell\ell b\bar{b}$ with $\ell$ denoting either electrons or muons and has to cope with overwhelming backgrounds from the dijet production expected from QCD interactions. Final state radiation and reconstruction effects may decrease the $b\bar{b}$ resonance resolution significantly while comparably decreasing the probability of observing the decay over the background. This talk presents the development and evaluation of advanced techniques to improve the invariant dijet mass reconstruction.

Speaker: Manuel Proissl (University of Edinburgh (GB))

Slides Proissl_IOP.pdf

88 Search for the Higgs Boson $b\bar{b}$ decay with the ATLAS detector

One of the main results of the Large Hadron Collider Run I was the discovery of the Higgs boson by ATLAS and CMS experiments. The boson has been discovered with a mass of around 125 GeV and all measurements performed so far are compatible with the Standard Model predictions. However, clear evidence of the boson decaying to a pair of $b$-quarks has not been observed yet, despite it being the dominant decay mode predicted by theory, making this a crucial measurement to establish the nature of the boson. The ATLAS search for the $b\bar{b}$ decay with the full Run I dataset is presented, considering the Higgs boson production in association with a vector boson ($W$, $Z$). The analysis is validated with a measurement of $WZ$ and $ZZ$ production, with $Z\rightarrow b\bar{b}$, which is found to be compatible with the Standard Model expectation.

Speaker: Ines Ochoa (University of London (GB))

Slides IOP_iochoa_080414.pdf

89 Search for the Standard Model Higgs Boson decaying to bb produced in association with a W boson with the ATLAS detector

The most recent published results for the ATLAS search for a Standard Model Higgs Boson decaying to bb in association with a W boson will be presented. The Higgs decay to bb is a crucial test of the Standard Model Higgs Boson but the search must be made in associated production modes. The search has been performed using 4.7 fb$^{-1}$ of data collected at $\sqrt{s}$=7TeV and 20.3 fb$^{-1}$ at $\sqrt{s}$=8TeV. No significant excess is observed and limits are placed on the cross section times branching ratio.

Speaker: Benedict Allbrooke (University of Birmingham (GB))

Slides WHbb.pdf

90 Using a Regressional Analysis to Improve the b-jet energy correction in $WH\rightarrow\ell\nu bb$ Searches at ATLAS

Presented is a method to improve the b-jet energy resolution with the task of increasing the signal sensitivity in searches decaying to a b, anti-b quark pair in the final state. The machinery has been tested using Monte Carlo simulated samples in the process $WH \rightarrow l\nu bb$. The method trains a function through regression applying a correction factor to bring the reconstructed jet energy closer to that of generator level energy. This narrows the b anti-b jet mass peak of the signal, and therefore increases the signal to background separation

Speaker: Thomas Olivier Ravenscroft (University of Glasgow (GB))

Slides travensc_Regression_iop_2014.pdf

91 Evidence for the 125GeV Higgs boson decaying to a pair of tau leptons at CMS

A search for the standard model Higgs boson decaying into a pair of tau leptons is presented, using data recorded by the CMS experiment in 2011 and 2012. The analysis includes all 6 possible final states of the two taus, each of which decays either hadronically or leptonically into an electron or muon. An excess of events over the expected contribution from backgrounds is observed, corresponding to a local significance of larger than 3 sigma for Higgs masses between 110 and 130 GeV. The excess is consistent with standard model predictions and provides evidence for the 125 GeV Higgs boson decaying into a pair of tau leptons.

Speaker: Rebecca Charlotte Lane (Imperial College Sci., Tech. & Med. (GB))

Slides RLane-IOP-HttEvidence_Final.pdf

92 Search for invisible Higgs decays in the VBF channel using the CMS detector

All measurements of the 125 GeV boson to date indicate compatibility with a SM Higgs boson, but the associated uncertainties are large, and the possibility for non-SM properties remains. In addition, although additional SM-like Higgs bosons have been excluded over a wide mass range, additional Higgs bosons with exotic decay modes remains a possibility, and are predicted by many models. Invisible Higgs boson decay modes are possible, for example, through decays to neutralinos in supersymmetric models, or graviscalars in models with extra dimensions. A search for invisible decays of Higgs bosons is present using the vector boson fusion production mode, using the full 2012 $\sqrt{s}=8$ TeV dataset recorded by the CMS experiment. Events are selected with a dedicated trigger based on the vector boson fusion tag jet topology, together with large missing transverse energy. The offline selection makes further use of the tag jet topology. The results of this analysis were further combined with the associated production ZH channel to obtain additional sensitivity.

Speaker: João Pela (Imperial College Sci., Tech. & Med. (GB))

Slides 20140407_IoP2014Meeting_JPela_VBFHiggsToInv.pdf

Parallel 2D: Dark Matter II / Exotic Searches

Convener: Session chair: Dr. Joseph Walding

93 Using cosmological data to study Dark Matter interactions with Standard Model particles

Despite the large number of dedicated experiments, an understanding of the particle nature of dark matter and direct evidence for its existence have remained elusive. However, detection methods generally assume that dark matter consists of cold, massive particles (CDM). In this talk, I will discuss how cosmological data from the CMB and Large-Scale Structure can be used to study dark matter interactions in a model-independent framework. I will show how small interactions with photons and neutrinos can have significant impact on structure formation, potentially solving key problems with the standard CDM cosmology.

Speaker: Mr Ryan Wilkinson (IPPP, Durham University)

Slides Ryan_Wilkinson_IOP_Seminar.pdf

94 The LZ dark matter experiment

The LUX-ZEPLIN (LZ) experiment is a next-generation search for Weakly Interacting Massive Particles, scaling the very successful double-phase xenon technology to multi-tonne target mass. LZ will be deployed at the 4850-ft level of the Sanford Underground Research Facility (South Dakota, USA) after completion of LUX, which is presently operating there. At its core, LZ will feature a 7-tonne (active) liquid xenon TPC surrounded by two outer ‘veto’ detectors. Particle interactions in the WIMP target generate two signatures: prompt scintillation light and ionisation charge, the latter transduced to a pulse of electroluminescence light in a thin gaseous layer above the liquid. Our strategy is to mitigate radiogenic backgrounds from detector materials through a combination of self-shielding, precise vertex location, coincidence vetoing, and xenon purification – to expose a background from astrophysical neutrinos. Electron recoils from solar pp neutrino scattering can be mostly discriminated by the ratio of the two signatures, which differs from that for nuclear recoil interactions which should be generated by WIMPs. We present the project status and the sensitivity reach of this exciting instrument.

Speaker: Henrique Araujo (Imperial College London)

Slides LZ-IOP-RHUL-HA140408.pdf

95 Building the background screening capability for LZ

The LZ dark matter experiment will require an unprecedented low background rate within its fiducial volume, defining strict constraints on radioactivity from construction materials that is further mitigated through the combination of powerful self-shielding from liquid xenon, 3D event vertex reconstruction, and external veto detector systems. An aggressive screening campaign with cutting-edge instrumentation must be performed, prior to construction, to measure the trace levels of radioisotopes in materials and construct the experiments background model. To provide sufficient sensitivity for LZ and next generation rare event search experiments we are re-developing the UK’s low-background screening capability. New ultra-low background HPGe detectors will be installed at the Boulby Underground Laboratory, itself undergoing substantial facility re-furbishment, to provide high sensitivity gamma spectroscopy for all DMUK and neutrino-less double beta decay interests. Dedicated low-activity mass spectrometry instrumentation is being developed at UCL for part per trillion level contaminant identification to complement underground screening for complete assays and deliver crucial throughput demands. Finally, emanation screening at UCL, developed for SuperNEMO, delivers mitigation of radon background inaccessible to gamma or mass spectrometry techniques.

Speaker: Dr Chamkaur Ghag (University College London)

Slides GhagLowBackgroundScreening.pdf

96 Beyond DEAP-3600: Development of a 50-tonne Next-Generation Liquid Argon Detector at SNOLAB

Building on the experience with single-phase Liquid Argon detectors, wich are particularly well-suited for high-mass WIMP sensitivity, I will present a conceptual design for a next-generation 50-tonne detector. In this large detector, surface background events which are one of the primary concerns for DEAP-3600, are mitigated more readily with position reconstruction, ultimately allowing a more conventional and cost-effective detector design. The high-discrimination of LAr of electronic events also mitigates the effect the neutrino background is the limiting factor in the ultimate sensitivity of all dark matter detectors.

Speaker: Simon Peeters (University of Sussex)

Slides IoP2014_CLEAN.pdf

97 The search for heavy neutrinos at NA62

Heavy neutrinos are predicted by many beyond-the-Standard-Model theories of particle physics, with proposed masses ranging from a few eV/$c^{2}$ up to the Planck scale. Two-body kaon decays provide a method to search for these particles in a model independent manner, for masses between 100 MeV/$c^{2}$ and 388 MeV/$c^{2}$. In 2007, the NA62 experiment at CERN collected a large sample of charged kaon decays with a low intensity beam and minimum bias trigger conditions, which can be used to put limits on the mixing between heavy neutrinos and the Standard Model muon neutrino. Here, the method is discussed and the predicted sensitivity is compared with existing limits in the literature.

Speaker: Francis Oliver Newson (University of Birmingham (GB))

Slides IOP2014.monday.pdf

98 A search for long lived neutral particles decaying to photons at the ATLAS detector

Long lived neutral particles that decay within the volume of a particle detector to a photon and a dark matter candidate will leave a unique signature which cannot be explained by any Standard Model process providing clear evidence of new physics. This talk will present an analysis performed on the data collected by the ATLAS Collaboration in 2011 at a center of mass energy of 7TeV searching for events containing two photons and a large amount of missing energy from the decay of long lived neutral particles. The results are interpreted in terms of Gauge Mediated Symmetry Breaking where the lightest neutralino is the long lived neutral particle which decays to a photon and a gravitino, the lightest Supersymmetric particle and dark matter candidate. Limits are set on the mass and the lifetime of the lightest neutralino. Improvements made to the method being used to analyse the 8TeV center of mass data collected in 2012 and preliminary results will also be presented.

Speaker: Allan Kenneth Lehan (University of Liverpool (GB))

Slides ALehan_IOP.pdf

99 Search for high-mass dilepton resonances in 21 fb$^{−1}$ of $pp$ collisions at $\sqrt{s} =$ 8 TeV with the ATLAS experiment

The ATLAS detector at the Large Hadron Collider is used to search for high mass resonances decaying to an electron-positron pair or a muon-antimuon pair. Results are presented from the analysis of pp collisions at a center-of-mass energy of 8 TeV corresponding to an integrated luminosity of approximately 21 $fb^{−1}$. A narrow resonance with Standard Model Z couplings to fermions is excluded at 95% C.L. for masses below 2.79 TeV in the electron channel, 2.53 TeV in the muon channel, and 2.90 TeV in the two channels combined. Limits on other model interpretations are also presented, including a Grand Unification model based on the E6 gauge group, $Z^∗$ bosons, Minimal $Z^{'}$ Models, a spin-2 Randall-Sundrum graviton, quantum black holes and a Minimal Walking Technicolor model with a composite Higgs boson.

Speaker: Marc Bret Cano (University of London (GB))

Slides presentation_IOP2014.pdf

100 Searches for violation of lepton flavour and baryon number in tau lepton decays at LHCb

We report on searches for the lepton-flavour violating decay $\tau^-\rightarrow\mu^-\mu^+\mu^-$ and the lepton-flavour and baryon-number violating decays $\tau^-\rightarrow p\mu^-\mu^-$ and $\tau^-\rightarrow\bar{p}\mu^+\mu^-$, carried out using 1.0 inverse femtobarn of proton-proton collision data taken by the LHCb experiment at 7 TeV during 2011. No evidence has been found for any signal, and limits have been set at 90% confidence level on the branching fractions: BF($\tau^-\rightarrow\mu^-\mu^+\mu^-$) $< 8.0 \times 10^{-8}$, BF($\tau^-\rightarrow p\mu^-\mu^-$) $< 3.3 \times 10^{-7}$ and BF($\tau^-\rightarrow\bar{p}\mu^+\mu^-$) < $4.6 \times 10^{-7}$. The result for BF($\tau^-\rightarrow\mu^-\mu^+\mu^-$) is consistent with previous limits, while the measurements of the $\tau^-\rightarrow p\mu^-\mu^-$ and $\tau^-\rightarrow\bar{p}\mu^+\mu^-$ decay modes represent the first experimental limits on these channels.

Speaker: Jon Harrison (University of Manchester (GB))

Slides IoP_2014.pdf

101 Axion search prospects with the LZ experiment

Whilst Weakly Interactive Massive Particles (WIMPs) remain the favoured candidates for dark matter, recent LHC results significantly constrain the available parameter space for several models, including supersymmetric neutralinos. Amongst alternative explanations for the astrophysical evidence of dark matter, axions – more specifically the so-called ‘invisible’ axions and axion-like-particles (ALPs) – are well motivated. Stars and the galaxy can be considered as the primary sources, while the most credited models presently are hadronic DFSZ and the GUT KSVZ. Liquid xenon is widely considered to be one of the best target media for detection of WIMPs using nuclear recoils. However these detectors also provide an extremely low radioactivity environment for electron recoils. Thus, very weakly interacting low-mass particles (<100 keV/c$^2$), such as the hypothetical axion, could be detected as well in this case using the axio-electric effect. This process is equivalent of a photo-electric effect with the absorption of an axion instead of a photon. We present the LZ potential for these searches, testing the axion coupling to electron (gAe) and setting constraints on the solar axion mass according to the aforementioned models.

Speaker: Dr Paolo Beltrame (University of Edinburgh)

Slides LZ_Axions_IoP_J_HEPP_&_APP_2014.pdf

6:15 PM End

Parallel 2E: Neutrino Oscillations

Convener: Session chair: Dr. Roxanne Guenette

102 Neutrino interactions and the T2K experiment

The T2K experiment is a long baseline neutrino oscillation experiment. One of the largest sources of uncertainty in neutrino oscillation experiments comes from our poor understanding of neutrino interaction cross-sections. I will explain why this is the case, and summarise the work that is being done to improve on the current situation.

Speaker: Mr Andrew Furmanski (University of Warwick)

Slides Furmanski_NeutrinoInteractions_IOP.pdf

103 Neutrinos in Gas at T2K

Cross-section measurements are extremely important for reducing systematic uncertainties in neutrino oscillation experiments, but are limited by our understanding of effects inside the target nucleus. Measuring neutrino interactions in gaseous detector allows the models used to simulate these effects to be empirically tested, thanks to the high spatial resolution of the detector and the relatively long range of even low-energy particles originating from the vertex (e.g. protons with a kinetic energy of 0.5 MeV). This talk will give a brief overview of the project of measuring these interactions in the ND280 time projection chambers, before focusing on my work in developing a veto to reject entering backgrounds. It will then cover the future prospects for this work, which aims to make a world first measurement of neutrino interactions on gaseous argon.

Speaker: Pip Hamilton (Imperial College London)

Slides IOP.pdf

104 Proton selection in the T2K near detector ND280

To study the neutrino interaction with one proton at the final state we need to make a proton selection. I will present my latest results of my proton selection. It is a very interesting channel and help us understand the CP violation in the lepton sector. The theory is well understood but the analysis is challenging as the background is much greater than the signal.

Speaker: Mr Michail Lazos (Liverpool University)

Slides Michail_Lazos_IOP_2014.pdf

105 Towards measuring charged current neutrino interactions in T2K’s electromagnetic calorimeters

We present the physics opportunities which can be explored with the Electromagnetic Calorimeters (ECals) of the Tokai-to-Kamioka (T2K) off-axis near detector (ND280). Due to the ECal's high mass, a large fraction of the neutrinos incident on ND280 interact within the constituent lead layers which form the ECal. This makes the ECal an excellent detector for use in making the world's first neutrino-lead charged current inclusive cross-section measurement at about 1 GeV as well as providing unique information about the T2K neutrino beam flux. The ECal reconstruction algorithms are currently tailored towards topologies for oscillation analyses. Such topologies prefer single charged particle tracks which originate from outside of the ECal fiducial volume. To fully reach the physics potential of the ECal, the reconstruction algorithms are being updated with a method of pattern recognition which is capable of reconstructing neutrino interaction vertices. The reconstruction enhancement, together with the large T2K dataset, will provide important information about the neutrino interaction picture.

Speaker: Mr Dominic Brailsford (Imperial College)

Slides DBrailsford_IOP2014_ECalNuInteractions.pdf

106 Selecting electron anti-neutrino charge current events in the ND280 tracker at T2K

In 2014 the T2K experiment will reverse the polarity of the magnetic horns and begin running with an anti-neutrino beam for the first time. Differences in the oscillation probabilities between neutrinos and anti-neutrinos may provide insight into charge-parity violation in the leptonic sector. In order to measure the the anti-electron neutrino contamination in T2K's anti-muon neutrino beam, an anti-neutrino selection has been developed for the ND280 near detector and tested using Monte-Carlo simulations of an anti-neutrino beam. The electron anti-neutrino selection faces new challenges not seen in the electron neutrino selection. The most significant challenge is the removal of protons which were removed by the charge requirement in the electron neutrino selection but are a significant background in the electron anti-neutrino analysis.

Speaker: Luke Southwell (Lancaster University)

Slides IOP_TALK.pdf

107 Sensitivities to neutrino oscillation parameters of the Hyper-K experiment

Hyper-Kamiokande is a next generation underground water Cherenkov detector which will serve as far detector of a long-baseline neutrino experiment in Japan (the natural extension of the already successful T2K experiment). The upgraded facilities at J-PARC will deliver an off-axis narrow band (~0.6 GeV) (anti-)neutrino beam (750kW~1MW) and direct it to Hyper-K that will measure the appearance and disappearance parameters with unprecedented precision as well as potentially discover CP violation in the lepton sector. Hyper-K consists of two cylindrical tanks lying side-by-side, whose total (fiducial) mass is 0.99 (0.56) million metric tons (about 20 (25) times larger than that of Super-K). The inner detector region of the Hyper-K detector is covered by 99,000 20-inch PMTs (20% photo-cathode coverage of PMT density). The near detector complex will include: INGRID and ND280 (on-axis and off-axis detector at 280 m from the target, already used by the T2K experiment) and a new near detector to be possibly built at 2 km from the target. The near detectors will help constraining the neutrino flux and systematic errors. If the mass hierarchy is known, Hyper-K is expected to determine the CP phase to better than 19 degrees for all possible values of delta and CP violation can be determined at 3 sigmas for 76% of the delta parameter space (considering 5 years exposure to neutrino beam produced by the 1.66 MW J-PARC proton synchrotron).

Speaker: Ms Linda Cremonesi (Queen Mary University of London)

Slides Cremonesi_HyperK_IoP.pdf

108 Near Detector Simulations in LAGUNA-LBNO

LAGUNA-LBNO (Large Appartus studying Grand Unification and Neutrino Astrophysics for Long Baseline Neutrino Oscillations) is a feasibility study with the intent to host next generation neutrino detectors. These experiments possess the ability to probe the universe further with proposed detectors of the 100 kton scale. A basic overview of the long baseline experiment is presented with the focus on the Near Detector design. Monte Carlo simulations form the basis of the study. A high pressure gas Argon TPC design is implemented and its capabilities are presented with neutrino energy reconstruction techniques employed.

Speaker: Mr Thomas Stainer (University of Liverpool)

Slides IoP2014_LAGUNA_talk.pdf

109 Neutrino Oscillation Search With MINOS+

Analysis of the complete set of MINOS accelerator and atmospheric data, combining `$\nu_{\mu}$` disappearance and `$\nu_{e}$` appearance, was published in March 2014. This yielded precision measurements of `$\Delta m^{2}_{32}$` and `$sin^{2}(\theta_{23})$` as well as early constraints on `$\delta_{CP}$`. The first results from MINOS+, adding 2 years of atmospheric and 6 months of beam `$\nu_{\mu}$` disappearance data to the MINOS analysis, are due in the summer. Here I present work towards these results.

Speaker: Mr Joseph O'Connor (University College London)

Slides joconnor_iop.pdf

110 Manifest causality in QFT with sources and detectors

In arXiv: 1312.3871, we introduce a way to compute transition amplitudes in quantum field theory for scatterings between sources and detectors, that is scatterings over finite space-time domains. Our amplitudes are manifestly causal, by which we mean that the source and detector are always linked by a connected chain of retarded propagators. We illustrate how these amplitudes may be obtained from a path-integral representation that closely resembles the in-in formalism of thermal field theory, introduced by Schwinger and Keldysh. Finally, we prove the tree-level equivalence of these amplitudes with the S-matrix and comment on potential deviations at the level of loops.

Speaker: Dr Peter Millington (University of Manchester and IPPP, Durham University)

Slides HEPPAPP_[Millington].pdf HEPPAPP_[Millington].pptx

111 The $N_2$-dominated scenario of leptogenesis

I shall briefly review the main aspects of leptogenesis, describing both the unflavoured and the flavoured versions of the $N_2$-dominated scenario. A study of the success rates of both classes of models has been carried out and I will comment on that, as well as on the incidence of corrective effects to the simplest scenario. I will then focus on the flavoured case and consider the conditions required by strong thermal leptogenesis, where the final asymmetry is fully independent of the initial conditions. Barring strong cancellations in the seesaw formula and in the flavoured decay parameters, I will show that strong thermal leptogenesis favours a lightest neutrino mass $m_1>\sim10\,\rm{meV}$ for normal ordering and $m_1>\sim3\,\rm{meV}$ for inverted ordering. Finally, I shall briefly comment on the power of future absolute neutrino mass scale experiment to either support or severely corner strong thermal leptogenesis. This work is mainly based on *arXiv:1401.6185*

Speaker: Mr Michele Re Fiorentin (University of Southampton)

7:00 PM Conference Banquet

Wed, April 9

Plenary 5: Near-Future Prospects

Convener: Session chair: Prof. Antonella De Santo

112 LHC Detector Upgrades

Over the next decade a series of upgrades to both the LHC machine and the experiments which operate at the LHC will be carried out. Some of them are already under way. A brief summary will be given of the motivations for detector upgrades, with the accelerator schedule as it is currently foreseen, and a short review of the major elements of the upgrade plans for the four LHC experiments, highlighting the most important challenges.

Speaker: Prof. Geoff Hall (Imperial College London)

Slides Hall_IoP_LHCUpgrades_0414.pdf Hall_IoP_LHCUpgrades_0414.pptx

113 The Next-Generation Particle Accelerator

Options for the next high-energy electron-positron collider are reviewed, by comparing a linear-collider design - the ILC - with proposed circular collider Higgs factories such as FCC-ee/TLEP. This presentation sketches relative construction costs, some key intrinsic features of circular and linear colliders, issues related to electrical power consumption, interaction-point spot sizes, luminosity potential, energy scaling laws, technical risks, empirical commissioning times, and several possible future scenarios.

Speaker: Dr Frank Zimmermann (CERN)

Slides The_Next_Accelerator_-_final.pdf The_Next_Accelerator_-_final.pptx

114 Future Long Baseline Neutrino Oscillation Experiments and Detectors

The next generation of accelerator neutrino oscillation experiments will have significant discovery potential for CP violation in the lepton sector. I will review the physics prospects of these experiments, with emphasis on the UK's role in them.

Speaker: Dr Morgan Wascko

Slides wascko_20140409.pdf

115 Gravitational Wave Detection: the Advanced Generation of Gravitational-Wave Detectors

This talk will cover the status of activities for the construction and commissioning of the imminent generation of the gravitational GW detectors due to start first science runs next year. It will focus on the status of and plans for the Advanced LIGO observatories (in Hanford Washington, and Livingston Louisiana, USA) and Advanced Virgo (near Cascina, Italy), and their operation in the global network.

Speaker: Prof. Sheila Rowan

Slides IoP_HEPP_AP_AGM_2014_SR.pptx

10:30 AM Coffee / Poster Session II

Plenary 6: Far-Future Programme

Convener: Session chair: Prof. Jordan Nash

116 Why do we live in a Matter Dominated Universe?

With the discovery of neutrino oscillations, the existence neutrino masses have been established pointing towards new Physics beyond the Standard Model. New compelling questions are open for the future: is lepton number conserved? Is there CP-violation? Where does the observed leptonic flavour structure come from? After a very brief overview of the related phenomenological issues, I will discuss the physics beyond the Standard Model which may be responsible for neutrino masses and how this can be related to the origin of the baryon asymmetry in the leptogenesis framework.

Speaker: Prof. Silvia Pascoli

Slides IOP2014.pdf

117 Particle Theory: Where We Go From Here

Speaker: Prof. John March-Russell

Slides IOPtalk.pdf

118 Accelerators: How Do We Get to 100 TeV?

Particle colliders for high-energy physics have been in the forefront of scientific discoveries for more than half a century. The accelerator technology of the colliders has progressed immensely, while the beam energy, luminosity, facility size, and cost have grown by several orders of magnitude. The method of colliding beams has not fully exhausted its potential but has slowed down considerably in its progress. I will briefly review the development of the collider technology, examine near-term collider projects that are currently under development, derive a simple scaling model for the cost of large accelerators and colliding beam facilities based on costs of 17 big facilities which have been either built or carefully estimated. The cost parametrization will guide our consideration of possible future frontier accelerator facilities. I will conclude with an attempt to look beyond the current horizon and to find what paradigm changes are necessary for breakthroughs in the field.

Speaker: Dr Vladimir Shiltsev

Slides IOP2014_Shiltsev_v2.pdf IOP2014_Shiltsev_v2.pptx

APP Group AGM

12:30 PM Lunch

Plenary 7: STFC Town Meeting and the Global Programme

119 Town Meeting: State of the STFC

Speaker: Prof. John Womersley (STFC)

Slides HEPP-APP_presentation_9_April_2014_FINAL.pdf

120 Science Board Report

Speaker: Prof. Matt Griffin

Slides Prog_Rev_HEPP_Meeting.pdf Prog_Rev_HEPP_Meeting.pptx

121 Q&A

122 The Global Strategy in Particle Physics

Speaker: Prof. Tatsuya Nakada (Ecole Polytechnique Federale de Lausanne (CH))

Slides Global_Strategy.pdf

123 Panel on Future Directions in Particle Physics

Speakers: Prof. Alison Davenport, Dave Wark (RAL / Imperial College London), Prof. Grahame Blair (STFC), Prof. John Womersley (STFC), Prof. Philip Burrows (Oxford University), Prof. Tatsuya Nakada (Ecole Polytechnique Federale de Lausanne (CH))