Implications of Gravitational Waves for Supersymmetric Grand Unification

Supersymmetric grand unification based on $SO(10)$ is one of the most attractive paradigms in physics beyond the Standard Model. Inspired by the recent NANOGrav signal, we discuss the implications of detecting a stochastic gravitational wave background emitted by a network of cosmic strings for the $SO(10)$ grand unification. Starting from a minimal model with multiple steps of symmetry breaking, we show that it generally prefers a high intermediate scale above $10^{14}\, \mathrm{GeV}$ that is favored by observable primordial gravitational waves. The observed spectrum can potentially narrow the possible range of the cosmic string scale and restricts the unified couplings and the unification scale by requiring gauge coupling unification. As an indirect consequence of the high cosmic string scale, the monopole abundance places non-trivial constraints on the theory. These are complementary to the proton decay constraints and probe different facets of supersymmetric $SO(10)$ unification theories.Comment: 9 pages, 1 figure, 3 table

Organocatalytic depolymerization of poly(trimethylene carbonate)

Aliphatic polycarbonates have attracted attention as degradable and sustainable materials contributing to the circular plastic economy. Their chemical recycling has not been sufficiently studied. In this study, the efficacy of organocatalysts for depolymerization of poly(trimethylene carbonate) (PTMC), a representative aliphatic polycarbonate, is investigated using several organic acids and bases. The hydrolysis of PTMC produces the water-soluble degradates propane-1,3-diol (PD) and CO2. A phosphazene base P2-t-Bu shows high activity for the hydrolysis, yielding up to 31% and 89% of PD in the homogeneous reaction at around 27°C and the inhomogeneous reaction under the reflux condition, respectively. By contrast, 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) exhibits exceptionally high catalytic activity for the methanolysis of PTMC, producing PD and dimethyl carbonate. This is because of dual hydrogen-bonding activation, which completes the inhomogeneous reaction in a few hours at around 27°C while yielding more than 90% of PD. The reaction rate of the TBD-catalyzed methanolysis depends on the concentration of the nucleophile and catalyst, and the ratio of the nucleophile to the substrate affects the PD yield. These results provide a highly promising standard for chemical recycling of functionalized aliphatic polycarbonates that could potentially be applied to sustainable materials in the future

Value of ADC measurements for nodal staging after chemoradiation in locally advanced rectal cancer—a per lesion validation study

OBJECTIVES: To evaluate the performance of diffusion-weighted MRI (DWI) in addition to T2-weighted (T2W) MRI for nodal restaging after chemoradiation in rectal cancer. METHODS: Thirty patients underwent chemoradiation followed by MRI (1.5 T) and surgery. Imaging consisted of T2W-MRI and DWI (b0, 500, 1000). On T2W-MRI, nodes were scored as benign/malignant by two independent readers (R1, R2). Mean apparent diffusion coefficient (ADC) was measured for each node. Diagnostic performance was compared for T2W-MRI, ADC and T2W+ADC, using a per lesion histological validation. RESULTS: ADC was higher for the malignant nodes (1.43 +/- 0.38 vs 1.19 +/- 0.27 *10(-3) mm(2)/s, p < 0.001). Area under the ROC curve/sensitivity/specificity were 0.88/65%/93% (R1) and 0.95/71%/91% (R2) using T2W-MRI; 0.66/53%/82% using ADC (mean of two readers); and 0.91/56%/98% (R1) and 0.96/56%/99% (R2) using T2W+ADC. There was no significant difference between T2W-MRI and T2W+ADC. Interobserver reproducibility was good for T2W-MRI (kappa0.73) and ADC (intraclass correlation coefficient 0.77). CONCLUSIONS: After chemoradiation, ADC measurements may have potential for nodal characterisation, but DWI on its own is not reliable. Addition of DWI to T2W-MRI does not improve accuracy and T2W-MRI is already sufficiently accurate

Androgen-Regulated Transcriptional Control of Sialyltransferases in Prostate Cancer Cells

The expression of gangliosides is often associated with cancer progression. Sialyltransferases have received much attention in terms of their relationship with cancer because they modulate the expression of gangliosides. We previously demonstrated that GD1a production was high in castration-resistant prostate cancer cell lines, PC3 and DU145, mainly due to their high expression of β-galactoside α2,3-sialyltransferase (ST3Gal) II (not ST3Gal I), and the expression of both ST3Gals was regulated by NF-κB, mainly by RelB. We herein demonstrate that GD1a was produced in abundance in cancerous tissue samples from human patients with hormone-sensitive prostate cancers as well as castration-resistant prostate cancers. The expression of ST3Gal II was constitutively activated in castration-resistant prostate cancer cell lines, PC3 and DU145, because of the hypomethylation of CpG island in its promoter. However, in androgen-depleted LNCap cells, a hormone-sensitive prostate cancer cell line, the expression of ST3Gal II was silenced because of the hypermethylation of the promoter region. The expression of ST3Gal II in LNCap cells increased with testosterone treatment because of the demethylation of the CpG sites. This testosterone-dependent ST3Gal II expression was suppressed by RelB siRNA, indicating that RelB activated ST3Gal II transcription in the testosterone-induced demethylated promoter. Therefore, in hormone-sensitive prostate cancers, the production of GD1a may be regulated by androgen. This is the first report indicating that the expression of a sialyltransferase is transcriptionally regulated by androgen-dependent demethylation of the CpG sites in its gene promoter

Aiming for tops of ALPs with a muon collider

Future muon colliders with center-of-mass energy of O (1 − 10) TeV can provide a clean high-energy environment with advantages in searches for TeV-scale axion-like particles (ALPs), pseudo-Nambu-Goldstone bosons associated with spontaneously broken global symmetries, which are widely predicted in physics beyond the Standard Model (SM). We exploit ALP couplings to SM fermions, and guided by unitarity constraints, build a search strategy focusing on the ALP decay to top quark pairs at muon colliders. It is found that a large parameter space of TeV-scale ALPs with TeV-scale decay constants can be probed by utilizing the ALP-top quark coupling

Deeply learned preselection of Higgs dijet decays at future lepton colliders

Future electron-positron colliders will play a leading role in the precision measurement of Higgs boson couplings which is one of the central interests in particle physics. Aiming at maximizing the performance to measure the Higgs couplings to the bottom, charm and strange quarks, we develop machine learning methods to improve the selection of events with a Higgs decaying to dijets. Our methods are based on the Boosted Decision Tree (BDT), Fully-Connected Neural Network (FCNN) and Convolutional Neural Network (CNN). We find that the BDT and FCNN algorithms outperform the conventional cut-based method. With our improved selection of Higgs decaying to dijet events using the FCNN, the charm quark signal strength is measured with a 16% error, which is roughly a factor of two better than the 34% precision obtained by the cut-based analysis. Also, the strange quark signal strength is constrained as μss≲35 at the 95% C.L. with the FCNN, which is to be compared with μss≲70 obtained by the cut-based method