Measurements of neutrino oscillation parameters from the T2K experiment using 3.6×1021 protons on target

The T2K experiment presents new measurements of neutrino oscillation parameters using 19.7 ( 16.3 ) × 10 20 protons on target (POT) in (anti-)neutrino mode at the far detector (FD). Compared to the previous analysis, an additional 4.7 × 10 20 POT neutrino data was collected at the FD. Significant improvements were made to the analysis methodology, with the near-detector analysis introducing new selections and using more than double the data. Additionally, this is the first T2K oscillation analysis to use NA61/SHINE data on a replica of the T2K target to tune the neutrino flux model, and the neutrino interaction model was improved to include new nuclear effects and calculations. Frequentist and Bayesian analyses are presented, including results on sin 2 θ 13 and the impact of priors on the δ CP measurement. Both analyses prefer the normal mass ordering and upper octant of sin 2 θ 23 with a nearly maximally CP-violating phase. Assuming the normal ordering and using the constraint on sin 2 θ 13 from reactors, sin 2 θ 23 = 0 . 561 - 0.032 + 0.021 using Feldman-Cousins corrected intervals, and Δ m 32 2 = 2 . 494 - 0.058 + 0.041 × 10 - 3 eV 2 using constant Δ χ 2 intervals. The CP-violating phase is constrained to δ CP = - 1 . 97 - 0.70 + 0.97 using Feldman-Cousins corrected intervals, and δ CP = 0 , π is excluded at more than 90% confidence level. A Jarlskog invariant of zero is excluded at more than 2 σ credible level using a flat prior in δ CP , and just below 2 σ using a flat prior in sin δ CP . When the external constraint on sin 2 θ 13 is removed, sin 2 θ 13 = 28 . 0 - 6.5 + 2.8 × 10 - 3 , in agreement with measurements from reactor experiments. These results are consistent with previous T2K analyses.

Triangle Singularity as the Origin of the a_{1}(1420)

The COMPASS Collaboration experiment recently discovered a new isovector resonancelike signal with axial-vector quantum numbers, the a_{1}(1420), decaying to f_{0}(980)π. With a mass too close to and a width smaller than the axial-vector ground state a_{1}(1260), it was immediately interpreted as a new light exotic meson, similar to the X, Y, Z states in the hidden-charm sector. We show that a resonancelike signal fully matching the experimental data is produced by the decay of the a_{1}(1260) resonance into K^{*}(→Kπ)K[over ¯] and subsequent rescattering through a triangle singularity into the coupled f_{0}(980)π channel. The amplitude for this process is calculated using a new approach based on dispersion relations. The triangle-singularity model is fitted to the partial-wave data of the COMPASS experiment. Despite having fewer parameters, this fit shows a slightly better quality than the one using a resonance hypothesis and thus eliminates the need for an additional resonance in order to describe the data. We thereby demonstrate for the first time in the light-meson sector that a resonancelike structure in the experimental data can be described by rescattering through a triangle singularity, providing evidence for a genuine three-body effect.

Search for Electron Antineutrino Appearance in a Long-Baseline Muon Antineutrino Beam

Electron antineutrino appearance is measured by the T2K experiment in an accelerator-produced antineutrino beam, using additional neutrino beam operation to constrain parameters of the Pontecorvo-Maki-Nakagawa-Sakata (PMNS) mixing matrix. T2K observes 15 candidate electron antineutrino events with a background expectation of 9.3 events. Including information from the kinematic distribution of observed events, the hypothesis of no electron antineutrino appearance is disfavored with a significance of 2.40σ and no discrepancy between data and PMNS predictions is found. A complementary analysis that introduces an additional free parameter which allows non-PMNS values of electron neutrino and antineutrino appearance also finds no discrepancy between data and PMNS predictions.

Search for CP Violation in Neutrino and Antineutrino Oscillations by the T2K Experiment with 2.2×10^{21} Protons on Target

The T2K experiment measures muon neutrino disappearance and electron neutrino appearance in accelerator-produced neutrino and antineutrino beams. With an exposure of 14.7(7.6)×10^{20} protons on target in the neutrino (antineutrino) mode, 89 ν_{e} candidates and seven anti-ν_{e} candidates are observed, while 67.5 and 9.0 are expected for δ_{CP}=0 and normal mass ordering. The obtained 2σ confidence interval for the CP-violating phase, δ_{CP}, does not include the CP-conserving cases (δ_{CP}=0, π). The best-fit values of other parameters are sin^{2}θ_{23}=0.526_{-0.036}^{+0.032} and Δm_{32}^{2}=2.463_{-0.070}^{+0.071}×10^{-3}  eV^{2}/c^{4}.

First Measurement of Transverse-Spin-Dependent Azimuthal Asymmetries in the Drell-Yan Process

The first measurement of transverse-spin-dependent azimuthal asymmetries in the pion-induced Drell-Yan (DY) process is reported. We use the CERN SPS 190  GeV/c π^{-} beam and a transversely polarized ammonia target. Three azimuthal asymmetries giving access to different transverse-momentum-dependent (TMD) parton distribution functions (PDFs) are extracted using dimuon events with invariant mass between 4.3  GeV/c^{2} and 8.5  GeV/c^{2}. Within the experimental uncertainties, the observed sign of the Sivers asymmetry is found to be consistent with the fundamental prediction of quantum chromodynamics (QCD) that the Sivers TMD PDFs extracted from DY have a sign opposite to the one extracted from semi-inclusive deep-inelastic scattering (SIDIS) data. We present two other asymmetries originating from the pion Boer-Mulders TMD PDFs convoluted with either the nucleon transversity or pretzelosity TMD PDFs. A recent COMPASS SIDIS measurement was obtained at a hard scale comparable to that of these DY results. This opens the way for possible tests of fundamental QCD universality predictions.

Combined Analysis of Neutrino and Antineutrino Oscillations at T2K

T2K reports its first results in the search for CP violation in neutrino oscillations using appearance and disappearance channels for neutrino- and antineutrino-mode beams. The data include all runs from January 2010 to May 2016 and comprise 7.482×10^{20} protons on target in neutrino mode, which yielded in the far detector 32 e-like and 135  μ-like events, and 7.471×10^{20} protons on target in antineutrino mode, which yielded 4 e-like and 66  μ-like events. Reactor measurements of sin^{2}2θ_{13} have been used as an additional constraint. The one-dimensional confidence interval at 90% for the phase δ_{CP} spans the range (-3.13, -0.39) for normal mass ordering. The CP conservation hypothesis (δ_{CP}=0, π) is excluded at 90% C.L.

Measurement of Coherent π^{+} Production in Low Energy Neutrino-Carbon Scattering

We report the first measurement of the flux-averaged cross section for charged current coherent π^{+} production on carbon for neutrino energies less than 1.5 GeV, and with a restriction on the final state phase space volume in the T2K near detector, ND280. Comparisons are made with predictions from the Rein-Sehgal coherent production model and the model by Alvarez-Ruso et al., the latter representing the first implementation of an instance of the new class of microscopic coherent models in a neutrino interaction Monte Carlo event generator. We observe a clear event excess above background, disagreeing with the null results reported by K2K and SciBooNE in a similar neutrino energy region. The measured flux-averaged cross sections are below those predicted by both the Rein-Sehgal and Alvarez-Ruso et al.

Measurement of Muon Antineutrino Oscillations with an Accelerator-Produced Off-Axis Beam

T2K reports its first measurements of the parameters governing the disappearance of ν[over ¯]_{μ} in an off-axis beam due to flavor change induced by neutrino oscillations. The quasimonochromatic ν[over ¯]_{μ} beam, produced with a peak energy of 0.6 GeV at J-PARC, is observed at the far detector Super-Kamiokande, 295 km away, where the ν[over ¯]_{μ} survival probability is expected to be minimal. Using a data set corresponding to 4.01×10^{20} protons on target, 34 fully contained μ-like events were observed. The best-fit oscillation parameters are sin^{2}(θ[over ¯]_{23})=0.45 and |Δm[over ¯]_{32}^{2}|=2.51×10^{-3}  eV^{2} with 68% confidence intervals of 0.38-0.64 and 2.26-2.80×10^{-3}  eV^{2}, respectively. These results are in agreement with existing antineutrino parameter measurements and also with the ν_{μ} disappearance parameters measured by T2K.

Observation of a New Narrow Axial-Vector Meson a1(1420)

The COMPASS Collaboration at CERN has measured diffractive dissociation of 190  GeV/c pions into the π(-)π(-)π(+) final state using a stationary hydrogen target. A partial-wave analysis (PWA) was performed in bins of 3π mass and four-momentum transfer using the isobar model and the so far largest PWA model consisting of 88 waves. A narrow peak is observed in the f0(980)π channel with spin, parity and C-parity quantum numbers J(PC)=1(++). We present a resonance-model study of a subset of the spin-density matrix selecting 3π states with J(PC)=2(++) and 4(++) decaying into ρ(770)π and with J(PC)=1(++) decaying into f0(980)π. We identify a new a1 meson with mass (1414(-13)(+15))  MeV/c2 and width (153(-23)(+8))  MeV/c2. Within the final states investigated in our analysis, we observe the new a1(1420) decaying only into f0(980)π, suggesting its exotic nature.

Measurement of the charged-pion polarizability

The COMPASS collaboration at CERN has investigated pion Compton scattering, π(-)γ→π(-)γ, at center-of-mass energy below 3.5 pion masses. The process is embedded in the reaction π(-)Ni→π(-)γNi, which is initiated by 190 GeV pions impinging on a nickel target. The exchange of quasireal photons is selected by isolating the sharp Coulomb peak observed at smallest momentum transfers, Q(2)<0.0015  (GeV/c)(2). From a sample of 63,000 events, the pion electric polarizability is determined to be α(π)=(2.0±0.6(stat)±0.7(syst))×10(-4)  fm(3) under the assumption α(π)=-β(π), which relates the electric and magnetic dipole polarizabilities. It is the most precise measurement of this fundamental low-energy parameter of strong interaction that has been addressed since long by various methods with conflicting outcomes. While this result is in tension with previous dedicated measurements, it is found in agreement with the expectation from chiral perturbation theory. An additional measurement replacing pions by muons, for which the cross-section behavior is unambiguously known, was performed for an independent estimate of the systematic uncertainty.

Advanced anal squamous cell carcinoma -- radiotherapy or surgery?

BACKGROUND

Anal and rectal cancers occupy the third position of death causes in Poland. Adenocarcinoma is the most frequent among the tumours in this group. Squamous cell carcinoma can be relatively less common. This kind of carcinoma may rather affect the anus than the rectum. Although the lesion is perceived as not very malignant and as such responsive to radiant energy therapy, some cases may require surgical treatment.

METHODS

Within 1999-2008 (the observation period of 10 years) there were 18 patients treated for anal squamous cell carcinoma at the Department of Thoracic Surgery, General and Oncological Surgery of the Medical University of Lodz, at the Surgical Department of the Ministry of Interior and Administration Hospital in Lodz and at the Teleradiotherapy Department of Mikolaj Kopernik Voivodship Specialist Hospital in Lodz. Each patient underwent radiochemotherapy with Mitomycin and 5-Fluorouracil and Lucovorin. The applied radiation doses ranged between 45-54 Gy in eighteen 2.0 Gy fractions. The abdomino-perineal resection of the rectum (APR) was performed in 3 patients (16.5%) who did not show full regression of the carcinoma. In all three cases the histopathological diagnosis preceded the surgical procedure.

RESULTS

For the total number of 18 patients with anal squamous cell carcinoma the mean observation period was 5.5 years, in the group of the operated patients the mean survival rate was 48 months (the median of 14-74 months) while for the group of the patients treated conservatively the mean survival rate amounted to 55 months (the median of 17-82 months, p=0.23). The mean 5-year disease-free survival rate was rather similar to the same rate of the general group, whereas the post-operative complications occurred in 66% of surgical procedures and 27% of teleradiotherapeutic procedures.

CONCLUSIONS

Combined radiotherapy and chemotherapy can be the method of choice in treating anal squamous cell carcinoma. Surgery should be used in advanced cases, when complete regression on radiochemotherapy cannot be observed. The abdomino-perineal resection of the rectum is the kind of a procedure that may be accompanied with a vast number of complications. Nevertheless, it still remains a necessary therapeutic method in the described cases.

Post-operative radiochemotherapy in patients with gastric cancer: one department's experience of 56 patients

OBJECTIVES

Prognosis in patients with locally advanced stomach cancer undergoing surgery alone is poor. High local failure rates in gastric cancer have been reported of up to 70%. When a relapse occurs, attempts at curative treatment are generally unsuccessful. A retrospective analysis was performed in order to determine whether post-operative radiochemotherapy improves treatment results in patients with locally advanced gastric cancer.

METHODS

Between November 2004 and July 2008, 56 patients with clinical Stage IB-IV cancer of the stomach underwent curative gastrectomy and adjuvant radiochemotherapy. Patients with distant metastases were excluded from the analysis. The total radiation dose was 45.0 Gy. The chemotherapy regimen comprised a 5 day cycle of 5-fluorouracil at 425 mg m(-2) and leucovorin at 20 mg m(-2). Overall survival and disease-free survival, as well as toxicity, were estimated for all patients.

RESULTS

Within the study group there were 7 (13%) local recurrences, 4 (7%) distant metastases and 8 (14%) local and distant relapses. The 2 year overall survival was 48%. A total of 19 (34%) patients developed Grade 3 gastrointestinal toxicity. There were no treatment-related deaths.

CONCLUSION

Post-operative radiochemotherapy is an effective and safe regimen in patients with curatively resected locally advanced gastric cancer.

Development of cyanide-resistant respiration in mitochondria from potato tubers treated with ethanol, acetaldehyde, and acetic acid

Treatment of intact potato (Solanum tuberosum L.) tubers with acetaldehyde, ethanol or acetic-acid vapors led to a respiratory upsurge which was further increased when the volatiles were applied in 100% O2. Mitochondria from tubers held in 100% O2 (O2 control) displayed a substrate state, state 3, and state 4 in respiration, whereas in mitochondria from the volatile-treated tubers the respiratory rate of the different states was virtually indistinguishable. This respiratory pattern was companied by the development of a cyanide-resistant respiration since these mitochondria exhibited resistance to CN and sensitivity to CN+salicylhydroxamic acid. Acetaldehyde-treated potatoes showed a time-course development (up to 36 h) of cyanide resistance and concomitant sensitivity to salicylhydroxamic acid, indicating the onset of synthetic processes leading to the observed changes in mitochondrial respiration.

Effect of ethanol, acetaldehyde, acetic Acid, and ethylene on changes in respiration and respiratory metabolites in potato tubers

Ethanol, acetaldehyde, and acetic acid, when applied in a volatile state in air to potato tubers, led to a climacteric-like upsurge in respiration. The respiratory upsurge was markedly enhanced when the volatiles were applied in 100% O(2).Ethanol induced a decline in the level of 2-phosphoglyceric acid and phosphoenolpyruvate while leading to the accumulation of tricarboxylic acid cycle intermediates including isocitrate and alpha-ketoglutarate. The action of these compounds was similar to, but independent of, the action of ethylene.

Factors Influencing the Development of Cyanide-resistant Respiration in Potato Tissue

Ethylene, cyanide gas, and volatalized ethanol, acetaldehyde, and acetic acid were applied in a continuous flow to whole potato tubers. Freshly cut slices were obtained periodically during the treatment, and showed a progressive development of a cyanide-resistant respiration. The application of the employed volatiles in 100% O(2) accelerated the onset and the magnitude of the cyanide-resistant respiration.These results show that, similar to ethylene and cyanide, the application of ethanol, acetaldehyde, or acetic acid can also lead to the development of cyanide-resistant respiration in whole potato tubers, and that this type of respiration is retained in freshly cut slices.

Effect of Ethylene and Oxygen on the Development of Cyanide-resistant Respiration in Whole Plant Mitochondria

Mitochondria from whole potatoes (Solanum tuberosum) ordinarily fail to oxidize respiratory substrates and to consume molecular O(2) in the presence of cyanide. Mitochondrial preparations obtained from tubers previously held for 24 hours in ethylene (10 microliters per liter) in air are only partially inhibited by cyanide. Application of ethylene in 100% O(2) led to an additional increase in the resistance of the mitochondrial respiration to cyanide. The resistance to cyanide was accompanied by a decrease in the respiratory control but no change in oxidative phosphorylation as shown by the measurement of ATP synthesis.The development of resistance to cyanide following the application of ethylene appears to require whole tubers and may represent an inductive process.

Cyanide-resistant Respiration in Freshly Cut Potato Slices

Treating intact white potato (Solanum tuberosum L.) tuber with ethylene in air or O(2) made it possible to obtain freshly cut slices which exhibit cyanide-resistant respiration. The cyanide-resistant path requires induction in whole tubers. The data also indicate that high O(2) concentration is necessary for the full development of cyanide-resistant respiration.