Search for Lepton-Flavor Violation in Z-Boson Decays with τ Leptons with the ATLAS Detector

A search for lepton-flavor-violating Z→eτ and Z→μτ decays with pp collision data recorded by the ATLAS detector at the LHC is presented. This analysis uses 139  fb^{-1} of Run 2 pp collisions at sqrt[s]=13  TeV and is combined with the results of a similar ATLAS search in the final state in which the τ lepton decays hadronically, using the same data set as well as Run 1 data. The addition of leptonically decaying τ leptons significantly improves the sensitivity reach for Z→ℓτ decays. The Z→ℓτ branching fractions are constrained in this analysis to B(Z→eτ)<7.0×10^{-6} and B(Z→μτ)<7.2×10^{-6} at 95% confidence level. The combination with the previously published analyses sets the strongest constraints to date: B(Z→eτ)<5.0×10^{-6} and B(Z→μτ)<6.5×10^{-6} at 95% confidence level.

Successful treatment of tumor stage mycosis fungoides with total skin helical tomotherapy

Total skin electron beam therapy (TSEBT) is a treatment option for mycosis fungoides (MF). In Japan, it has been rarely performed because of the time required for each treatment, physical burden on patients, and difficulties in providing uniform dosimetry. In recent years, helical tomotherapy, an intensity-modulated radiation therapy that applies helical computed tomography technology, has been used to treat cancer. Total skin helical tomotherapy (TSHT) has been suggested as a promising alternative to TSEBT for patients with MF, but there are few reports from Japan. We used TSHT to treat a 28-year-old Japanese woman with tumor stage MF. She achieved complete remission with TSHT (12 Gy in six fractions over 6 days) and remained in remission for 32 months without additional treatment. Treatment-related grade 4 myelosuppression was observed, but resolved with blood transfusions and subcutaneous injection of granulocyte colony stimulating factor. Other adverse events were tolerable. Although careful attention should be paid to myelosuppression, TSHT might be a useful treatment option for MF.

Search for New Phenomena in Final States with Two Leptons and One or No b-Tagged Jets at sqrt[s]=13 TeV Using the ATLAS Detector

A search for new phenomena is presented in final states with two leptons and one or no b-tagged jets. The event selection requires the two leptons to have opposite charge, the same flavor (electrons or muons), and a large invariant mass. The analysis is based on the full run-2 proton-proton collision dataset recorded at a center-of-mass energy of sqrt[s]=13  TeV by the ATLAS experiment at the LHC, corresponding to an integrated luminosity of 139  fb^{-1}. No significant deviation from the expected background is observed in the data. Inspired by the B-meson decay anomalies, a four-fermion contact interaction between two quarks (b, s) and two leptons (ee or μμ) is used as a benchmark signal model, which is characterized by the energy scale and coupling, Λ and g_{*}, respectively. Contact interactions with Λ/g_{*} lower than 2.0 (2.4) TeV are excluded for electrons (muons) at the 95% confidence level, still far below the value that is favored by the B-meson decay anomalies. Model-independent limits are set as a function of the minimum dilepton invariant mass, which allow the results to be reinterpreted in various signal scenarios.

Real-Space Observation of Emergent Complexity of Phase Evolution in Micrometer-Sized IrTe_{2} Crystals

We report complex behaviors in the phase evolution of transition-metal dichalcogenide IrTe_{2} thin flakes, captured with real-space observations using scanning Raman microscopy. The phase transition progresses via growth of a small number of domains, which is unlikely in statistical models that assume a macroscopic number of nucleation events. Consequently, the degree of phase evolution in the thin flakes is quite variable for the selected specimen and for a repeated measurement sequence, representing the emergence of complexity in the phase evolution. In the ∼20-μm^{3}-volume specimen, the complex phase evolution results in the emergent coexistence of a superconducting phase that originally requires chemical doping to become thermodynamically stable. These findings indicate that the complexity involved in phase evolution considerably affects the physical properties of a small-sized specimen.

Epistaxis limits the performed activities of daily living in proportion to its severity: a cross-sectional survey among patients with hereditary haemorrhagic telangiectasia

Background: We examined the severity of epistaxis in patients with hereditary haemorrhagic telangiectasia (HHT) and its relationship with the performed activities of daily living. Methodology: This cross-sectional survey included 36 patients with HHT in Japan. An anonymous questionnaire survey was conducted regarding the severity of epistaxis, the measures adopted to prevent epistaxis, and the limitations in the performed activities of daily living. The latter was assessed using a visual analogue scale (VAS). The correlation between epistaxis severity and the VAS score was analysed using Spearman’s rank correlation coefficient. Results: Of the 36 participants surveyed, 94.4% had >1 episode of epistaxis/week. The mean epistaxis severity score (ESS) was 4.3 (range, 0.9–8.4). Limitations in daily life, going out (within a day), meeting with others, eating with others, and going on overnight trips were positively correlated with the ESS. To prevent nosebleeds, 44.4% and 41.7% of the participants used medications and avoided drying their nasal cavities, respectively. Conclusions: Epistaxis impacted the daily life of patients with HHT in proportion to its severity. Nonetheless, less than half of the patients used medications or took precautions. Hence, further educational activities should be considered for medical professionals and patients.

Search for Displaced Leptons in sqrt[s]=13 TeV pp Collisions with the ATLAS Detector

A search for charged leptons with large impact parameters using 139  fb^{-1} of sqrt[s]=13  TeV pp collision data from the ATLAS detector at the LHC is presented, addressing a long-standing gap in coverage of possible new physics signatures. Results are consistent with the background prediction. This search provides unique sensitivity to long-lived scalar supersymmetric lepton partners (sleptons). For lifetimes of 0.1 ns, selectron, smuon, and stau masses up to 720, 680, and 340  GeV, respectively, are excluded at 95% confidence level, drastically improving on the previous best limits from LEP.