Direct Searches For New Physics Research Articles

Publishing statistical models: Getting the most out of particle physics experiments

The statistical models used to derive the results of experimental analyses are of incredible scientific value and are essential information for analysis preservation and reuse. In this paper, we make the scientific case for systematically publishing the full statistical models and discuss the technical developments that make this practical. By means of a variety of physics cases - including parton distribution functions, Higgs boson measurements, effective field theory interpretations, direct searches for new physics, heavy flavor physics, direct dark matter detection, world averages, and beyond the Standard Model global fits - we illustrate how detailed information on the statistical modelling can enhance the short- and long-term impact of experimental results.

Anomalous triple-gauge-boson interactions in vector-boson pair production with Recola2

Diboson production at the LHC is a process of great importance both in the context of tests of the SM and for direct searches for new physics. In this paper we present a phenomenological study of mathrm {W}mathrm {W} (rightarrow mathrm {e^+}nu _{mathrm {e}}mathrm {mu ^-}bar{nu }_{mu }), mathrm {W}mathrm {Z} (rightarrow mathrm {e^-}overline{nu }_{mathrm{e}} mu ^+ mu ^-), and mathrm {Z}mathrm {Z} (rightarrow mathrm {e^+}mathrm {e^-}mu ^+ mu ^-) production considering event selections of interest for the anomalous triple-gauge-boson-coupling searches at the LHC: we provide theoretical predictions within the Standard Model at NLO QCD and NLO EW accuracy and study the effect of the anomalous triple-gauge-boson interactions at NLO QCD. For mathrm {W}mathrm {W} and mathrm {Z}mathrm {Z} the contribution of the loop-induced mathrm {g}mathrm {g}rightarrow mathrm {W}^+mathrm {W}^- and mathrm {g}mathrm {g}rightarrow mathrm {Z}mathrm {Z} processes is included. Anomalous triple-gauge-boson interactions are parametrized in the EFT framework. This paper is the first application of Recola2 in the EFT context.

The Mu2e crystal calorimeter

The Mu2e Experiment at Fermilab will search for coherent, neutrino-less conversion of negative muons into electrons in the field of an Aluminum nucleus, μ− + Al → e− +Al. Data collection start is planned for the end of 2021. The dynamics of such charged lepton flavour violating (CLFV) process is well modelled by a two-body decay, resulting in a mono-energetic electron with an energy slightly below the muon rest mass. If no events are observed in three years of running, Mu2e will set an upper limit on the ratio between the conversion and the capture rates Rμe = μ− + A(Z,N) → e− + A(Z,N)/μ− + A(Z,N) → νμ− + A(Z−1,N) of ⩽ 6 × 10−17 (@ 90% C.L.). This will improve the current limit of four order of magnitudes with respect to the previous best experiment. Mu2e complements and extends the current search for μ → e γ decay at MEG as well as the direct searches for new physics at the LHC . The observation of such CLFV process could be clear evidence for New Physics beyond the Standard Model. Given its sensitivity, Mu2e will be able to probe New Physics at a scale inaccessible to direct searches at either present or planned high energy colliders. To search for the muon conversion process, a very intense pulsed beam of negative muons (∼ 1010 μ/sec) is stopped on an Aluminum target inside a very long solenoid where the detector is also located. The Mu2e detector is composed of a straw tube tracker and a CsI crystals electromagnetic calorimeter. An external veto for cosmic rays surrounds the detector solenoid. In 2016, Mu2e has passed the final approval stage from DOE and has started its construction phase. An overview of the physics motivations for Mu2e, the current status of the experiment and the required performances and design details of the calorimeter are presented.

The Belle II imaging Time-of-Propagation (iTOP) detector

High precision flavor physics measurements are an essential complement to the direct searches for new physics at the LHC ATLAS and CMS experiments. Such measurements will be performed using the upgraded Belle II detector that will take data at the SuperKEKB accelerator. With 40x the luminosity of KEKB, the detector systems must operate efficiently at much higher rates than the original Belle detector. A central element of the upgrade is the barrel particle identification system. Belle II has built and installed an imaging-Time-of-Propagation (iTOP) detector. The iTOP uses quartz optics as Cherenkov radiators. The photons are transported down the quartz bars via total internal reflection with a spherical mirror at the forward end to reflect photons to the backward end where they are imaged onto an array of segmented Micro-Channel Plate Photo-Multiplier Tubes (MCP-PMTs). The system is read out using giga-samples per second waveform sampling Application-Specific Integrated Circuits (ASICs). The combined timing and spatial distribution of the photons for each event are used to determine particle species. This paper provides an overview of the iTOP system.

Cosmological Reflection of Particle Symmetry

The standard model involves particle symmetry and the mechanism of its breaking. Modern cosmology is based on inflationary models with baryosynthesis and dark matter/energy, which involves physics beyond the standard model. Studies of the physical basis of modern cosmology combine direct searches for new physics at accelerators with its indirect non-accelerator probes, in which cosmological consequences of particle models play an important role. The cosmological reflection of particle symmetry and the mechanisms of its breaking are the subject of the present review.

Measurement of the Higgs Boson Coupling to the Top Quark and the Higgs Boson Self-coupling at the ILC

The International Linear Collider is a proposed 50 km electron-positron collider in the Kitakami hills in northern Japan. Precision measurements of Higgs properties and direct searches for new physics will complement the LHC experiments and their upgrades in our drive to answer open questions about the universe and the origin of matter. Two detector concepts have been validated as being feasible to deliver the necessary precision. In its baseline configuration the machine has a collision energy of about 500 GeV, upgradeable to 1 TeV. The electron beam is 80% polarized. The polarization of the positron beam is 30% at 500 GeV and 20% at 1 TeV. The integrated luminosity in a high-luminosity scenario is 1.6 ab-1 at 500 GeV and 2.5 ab-1 at 1 TeV. The measurements of the Higgs boson self-coupling and the coupling to the top quark are important pieces of the ILC physics program.

Interplay of flavor and collider physics

We present an overview on the interplay between direct searches for new physics at the LHC and indirect constraints from flavor physics, with an emphasis on the implications of the recent LHCb results. The complementarity with the Higgs search results will also be addressed. We show the correlations and complementarity between the different sectors in the context of a few specific scenarios in supersymmetry.

Belle II Status and Plans

To deepen our understanding of nature it is essential to complement the direct searches for new physics at the LHC by high precision flavor physics measurements. The next-generation B factory experiment Belle II at the upgraded KEKB accelerator, SuperKEKB, is designed to perform such measurements. The status of the collider and the Belle II detector is presented in this article.

Direct searches for new physics at the Terascale with a high-precision neutrino scattering experiment: NuSOnG

High-precision neutrino scattering at energies of order 100 GeV offers a clean probe of Beyond Standard Model physics at the Terascale. NuSOnG (Neutrino Scattering On Glass) is a high-statistics neutrino experiment which has been developed under that principle and has been proposed to run at the Fermilab Tevatron in year 2015. One of its strongest features is that it offers a unique opportunity for direct searches for new physics at TeV-scale energies, providing information complementary to that of the LHC. NuSOnG is sensitive to an unmatchable spectrum of new physics: from new light neutrino properties, to new interactions manifested through rare events, to new particles such as light neutrissimos, light vector bosons, etc. A particular example which illustrates the experiment's discovery potential, is the search for evidence of ‘matrix freedom’ or non- unitarity in the neutrino sector. Non-unitarity can manifest itself in a number of ways, such as flavor-dependent neutrino couplings, or instantaneous flavor transitions, both of which would cause observable effects at NuSOnG. This poster presents these examples, thus highlighting the truly rich discovery potential of the experiment.