Experimental Particle Physics

The next four-year timescale is particularly exciting with the exploitation of the LHC and upgrade developments at a critical stage. We will focus our efforts in the Higgs and top sectors for ATLAS, in the kaon sector for NA62, and in the charm and beauty sector for LHCb and in the neutrino sector at T2K and Hyper-K, including searches for BSM processes in each case. We are simultaneously entering a major construction phase which will require significant effort, building upon the synergies established between our ATLAS, LHCb and Linear Collider detector developments. We have undergone a significant transition in the neutrino sector where we have joined the T2K collaboration, contributing to its near detector upgrade through the WAGASCI/BabyMIND detectors, as a major step towards future neutrino developments. With the international community, we will contribute to the leadership needed to establish a future Linear Collider as part of the 2020 European strategy. We have developed detector development and construction capacity to contribute to our programme and have built up our technician and engineering effort in a carefully planned approach. Improved analysis techniques, well-calibrated detectors, increased computing power and theoretical input will be essential and we are at the forefront of the required developments in these areas. Most academics are heavily involved in the CERN programme and our strategy is to generate leading-edge physics results from ATLAS, LHCb and NA62 based upon expertise developed in those experiments. Having secured high-quality completion in Run 2 with significant results in Higgs H->bb modes and top production for ATLAS, we will exploit this experience to lead future ATLAS publications. Taking advantage of our work on boosted topologies and exploiting the larger Run 3 dataset, we will explore more extreme regions of phase space and use theoretical input to guide the interpretation of our results. For LHCb, we will measure the CKM angle gamma from loop and tree dominated B decays, search for CP violation and measure mixing parameters in charm decays. We will explore the spectrum of doubly-charmed baryons and measure the properties of the discovered states. For NA62 we will maintain UK computing expertise and will contribute to the analysis of the K->pi nu nu channel. We continue to invest in and promote a world-class Detector Development activity to enable longer-term initiatives and our Grid strength is aimed at maximising our impact in LHC physics as well as promoting new areas such as the linear collider. We additionally lever significant support through the University in these areas. We have set up physics analysis streams for each experiment, using the Grid, and will continue to fully exploit the LHC Run 3 data. We will also develop our involvement in longer-term initiatives exploiting our leadership roles. We presently have leading roles in the ATLAS and LHCb upgrades, the linear collider and future neutrino initiatives, such as T2K upgrades and Hyper-K. Over the next four years we will develop these areas and progress those where early investment will become most productive, consistent with our highest priority of LHC and neutrino physics exploitation. To enhance the priority programme, we have invested in generic detector developments leading to significant impact in sensors technologies. We have developed new capabilities in flip-chip bonding and chip design, complemented our well established core expertise. This has ensured that we can retain expertise in order to meet our priorities in silicon detector development via support of the LHC upgrade and other programmes. We anticipate working with the IGR and JWNC groups where we gain from joint facilities. This strategy is well suited to the skills and capacity of our core group. The associated responsive effort will be essential at a critical point in the evolution of UK particle physics.