Session C09: Beyond Standard Model Physics I

EFT of NonStandard neutrino Interactions

We present an effective theory for neutrino interactions with quarks, gluons and photons that includes operators up to dimension 7. We perform a matching of these operators into nucleon operators in order to describe low energy processes as the recently observed coherent scattering on nuclei. We compare the contribution of these new interactions with the results from COHERENT and CHARM experiments to obtain bounds on the new couplings both in the low and high energy regime. We finally review different models that can give rise to such NonStandard Interactions.   

Bump-Hunt Analysis on the 2016 Data of the Heavy Photon Search (HPS) Experiment

Theoretical and phenomenological considerations motivate the existence of a massive gauge boson associated with a new, broken U(1) gauge symmetry. This particle, called a ``heavy photon" ($A'$), would interact feebly with electrically charged particles in the Standard Model through kinetic mixing with the Standard Model photon, allowing it to be produced and detected in a laboratory setting. The Heavy Photon Search Experiment (HPS) at Jefferson Lab uses an electron beam striking a fixed tungsten foil target to attempt to produce $A'$s and detect their decay products, an $e^+e^-$ pair. HPS consists of a silicon vertex tracker inside a dipole magnet and an electromagnetic calorimeter for triggering and electron identification. The $A'$ signal would be a peak with the experimental resolution on top of a much larger QED background through both bump-hunting and a displaced vertex searches. HPS has had two successful preliminary runs at 1.05 GeV beam energy in 2015 and 2.3 GeV in 2016. Experimental setup, performance and future prospects will be summarized, while the focus of this talk will be on the bump-hunt analysis on the 2016 run.   

Dinucleon and Nucleon Decay into Two-Body Final States with No Hadrons

The violation of baryon number ($B$) is a consequence of many grand unified theories and is also one of the Sakharov conditions for baryogenesis. The Super-Kamiokande detector is a 50-kiloton tank of ultra-pure water (containing $1.2 \times 10^{34}$ nucleons) that is used to detect neutrinos and search for baryon number violating processes. In addition to searching for $\Delta B = 1$ decays such as proton decay, Super-Kamiokande data can be used to search for decays where $\Delta B = 2$. One type of $\Delta B = 2$ decay is dinucleon decay, where two nucleons in an oxygen atom decay together. We search for 10 dinucleon and proton decay modes which are characterized by a two-body final state with no hadrons. For example, our search included the dinucleon decay mode $pp \rightarrow e^{+}e^{+}$, and the proton decay mode $p \rightarrow e^{+}\gamma$. We use Super-Kamiokande data from April 1996 to April 2016, with a total exposure of 0.35 megaton-years. Here we present the search results and discuss their consequences.   

Search for New Physics with Emerging Jets

Many extensions of the Standard Model of Particle Physics that address open issues, such as dark matter and baryogenesis, call for long-lived particles that decay at macroscopic distance from the interaction point, which often result in unconventional signatures in the detector. These can easily escape the scrutiny of the existing prompt searches at the LHC. Therefore, the vast class of interesting long-lived phenomena presents rich discovery opportunities for the (HL-)LHC. In this talk I will particularly focus on a model of dark-QCD with a peculiar signature consisting of emerging jets.   

Abstract Withdrawn

Several beyond the Standard Model theories, including Composite Higgs, predict the existence of fermionic resonances that could be observed at the TeV scale. This talk presents a search for such a fermionic resonance, known as a "vector-like quark". This search specifically targets pair-produced vector-like quarks (T,B) decaying to fully-hadronic final states in $pp$ collisions at $\sqrt{s}=$ 13 TeV with the ATLAS detector. All allowed fully-hadronic decay modes are considered, and the results are interpreted in terms of SU(2) singlet and doublet models.   

A Search for Fully Hadronic Mode Vector-Like Quark Pair Production in 13 TeV pp Collisions using CMS Data

We describe a search for the production of a pair of vector-like quarks (VLQ's) with masses greater than 1000 GeV/c$^2$ decaying into a $b$ quark and a Higgs Boson using 13 TeV center-of-mass, proton-proton collision data from the CMS Experiment. Since the predominant decay mode of the Higgs Boson is to a $b \bar{b}$ pair, the analysis focuses on a final state consisting of jets resulting from the $b(\bar{b})$ quarks produced in the VLQ decays. We use a $\chi^2$ procedure based on the Higgs masses and the equality of the two VLQ masses to select the correct combinations of jets. Requiring that the jets are consistent with the production of a pair of Higgs and that the reconstructed VLQ's have equal masses greatly reduces the background from Standard Model processes. Since for highly boosted Higgs, the two jets resulting from the daughter $b(\bar{b})$ quarks might merge into a single jet, we present three independent analyses depending on the number of observed jets and the number of high invariant-mass jets. We present expected exclusion limits using 81 fb$^{-1}$ of integrated luminosity collected at CMS in 2016 and 2017.   

Searching for Dark Matter with Boosted Higgs Bosons in $pp$ collisions at $\sqrt{s}=$ 13 TeV with the ATLAS detector

If Dark Matter interacts with Standard Model particles, it could be possible to pair produce Dark Matter in association with another particle at a collider such as the LHC. If this other particle is a Higgs boson, the process is called “mono-Higgs,” since the resulting signature is a single boosted Higgs boson, reconstructed using advanced jet techniques, balanced by missing energy from the undetected Dark Matter particles. I will present the latest results of the mono-Higgs search using data taken from $pp$ collisions at $\sqrt{s}=$ 13 TeV with the ATLAS detector, including model-independent limits and limits on a 2HDM simplified model. In order to increase the sensitivity reach of the search for future iterations, I have worked closely on the development of new boosted Higgs tagging techniques, including the use of variable radius (VR) track jets. These new techniques, and their performances, will also be presented, and their application to the mono-Higgs and other BSM searches will be discussed.   

Search for Non-thermal Dark Matter in Monojet Events in Proton-Proton Collisions at $\sqrt{s}$ = 13 TeV

We will present a search for dark matter in events with one or more jets and large missing transverse energy using proton-proton collisions at center-of-mass energy of 13 TeV. The data was collected in 2016 by the Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC) corresponding to an integrated luminosity of 35.9 $\text{fb}^{-1}$. The results are interpreted in terms of Light Non-thermal dark matter model which explains presence of dark matter as well as baryon asymmetry in the universe. Model independent limit on narrow resonance is also obtained for monojet dominant coupling parameter space. There is no evidence for an excess of events above the background processes in the signal region, therefore cross section limits are set for different mediator masses.