Is there a non-Standard-Model contribution in non-leptonic b -> s decays?

Precision measurements of branching fractions and CP asymmetries in non-leptonic b -> s decays reveal certain "puzzles" when compared with Standard Model expectations based on a global fit of the CKM triangle and general theoretical expectations. Without reference to a particular model, we investigate to what extent the (small) discrepancies observed in (B -> J/psi K), (B -> phi K) and (B -> K pi) may constrain new physics in (b -> s q qbar) operators. In particular, we compare on a quantitative level the relative impact of different quark flavours q=c,s,u,d.Comment: 25 pages, 7 figures, some references added, brief discussion of B -> J/psi \pi include

Theoretical Investigation of Carrier-selective Contacts Featuring Tunnel Oxides by Means of Numerical Device Simulation

AbstractRecently, a variety of different n-type Si solar cells with carrier-selective contacts featuring tunnel oxides achieving remarkable cell results has been presented. Theoretical investigations on this topic are rare, especially simulations actually accounting for tunneling through the oxide interlayer. In this work we investigate the influence of different parameters affecting the passivation quality and thus the device performance by means of numerical device simulation. Thereby, a fundamental understanding of solar cells with carrier-selective contacts featuring tunnel oxides is generated which is essential to further develop this promising technology

Sequential Flavour Symmetry Breaking

The gauge sector of the Standard Model (SM) exhibits a flavour symmetry which allows for independent unitary transformations of the fermion multiplets. In the SM the flavour symmetry is broken by the Yukawa couplings to the Higgs boson, and the resulting fermion masses and mixing angles show a pronounced hierarchy. In this work we connect the observed hierarchy to a sequence of intermediate effective theories, where the flavour symmetries are broken in a step-wise fashion by vacuum expectation values of suitably constructed spurion fields. We identify the possible scenarios in the quark sector and discuss some implications of this approach.Comment: 22 pages latex, no figure

Partition Function Zeros of a Restricted Potts Model on Lattice Strips and Effects of Boundary Conditions

We calculate the partition function $Z(G,Q,v)$ of the $Q$-state Potts model exactly for strips of the square and triangular lattices of various widths $L_y$ and arbitrarily great lengths $L_x$, with a variety of boundary conditions, and with $Q$ and $v$ restricted to satisfy conditions corresponding to the ferromagnetic phase transition on the associated two-dimensional lattices. From these calculations, in the limit $L_x \to \infty$, we determine the continuous accumulation loci ${\cal B}$ of the partition function zeros in the $v$ and $Q$ planes. Strips of the honeycomb lattice are also considered. We discuss some general features of these loci.Comment: 12 pages, 12 figure

Thermoconditional modulation of the pleiotropic sensitivity phenotype by the Saccharomyces cerevisiae PRP19 mutant allele pso4-1

The conditionally-lethal pso4-1 mutant allele of the spliceosomal-associated PRP19 gene allowed us to study this gene’s influence on pre-mRNA processing, DNA repair and sporulation. Phenotypes related to intron-containing genes were correlated to temperature. Splicing reporter systems and RT–PCR showed splicing efficiency in pso4-1 to be inversely correlated to growth temperature. A single amino acid substitution, replacing leucine with serine, was identified within the N-terminal region of the pso4-1 allele and was shown to affect the interacting properties of Pso4-1p. Amongst 24 interacting clones isolated in a two-hybrid screening, seven could be identified as parts of the RAD2, RLF2 and DBR1 genes. RAD2 encodes an endonuclease indispensable for nucleotide excision repair (NER), RLF2 encodes the major subunit of the chromatin assembly factor I, whose deletion results in sensitivity to UVC radiation, while DBR1 encodes the lariat RNA splicing debranching enzyme, which degrades intron lariat structures during splicing. Characterization of mutagen-sensitive phenotypes of rad2{Delta}, rlf2{Delta} and pso4-1 single and double mutant strains showed enhanced sensitivity for the rad2{Delta} pso4-1 and rlf2{Delta} pso4-1 double mutants, suggesting a functional interference of these proteins in DNA repair processes in Saccharomyces cerevisiae

Exact Potts Model Partition Function on Strips of the Triangular Lattice

In this paper we present exact calculations of the partition function $Z$ of the $q$-state Potts model and its generalization to real $q$, for arbitrary temperature on $n$-vertex strip graphs, of width $L_y=2$ and arbitrary length, of the triangular lattice with free, cyclic, and M\"obius longitudinal boundary conditions. These partition functions are equivalent to Tutte/Whitney polynomials for these graphs. The free energy is calculated exactly for the infinite-length limit of the graphs, and the thermodynamics is discussed. Considering the full generalization to arbitrary complex $q$ and temperature, we determine the singular locus ${\cal B}$ in the corresponding ${\mathbb C}^2$ space, arising as the accumulation set of partition function zeros as $n \to \infty$. In particular, we study the connection with the T=0 limit of the Potts antiferromagnet where ${\cal B}$ reduces to the accumulation set of chromatic zeros. Comparisons are made with our previous exact calculation of Potts model partition functions for the corresponding strips of the square lattice. Our present calculations yield, as special cases, several quantities of graph-theoretic interest.Comment: 43 pages, latex, 24 postscript figures, Physica A, in pres

A Note on the Approximability of Deepest-Descent Circuit Steps

Linear programs (LPs) can be solved by polynomially many moves along the circuit direction improving the objective the most, so-called deepest-descent steps (dd-steps). Computing these steps is NP-hard (De Loera et al., arXiv, 2019), a consequence of the hardness of deciding the existence of an optimal circuit-neighbor (OCNP) on LPs with non-unique optima. We prove OCNP is easy under the promise of unique optima, but already $O(n^{1-\varepsilon})$-approximating dd-steps remains hard even for totally unimodular $n$-dimensional 0/1-LPs with a unique optimum. We provide a matching $n$-approximation

Occurrence of high and low Mr forms of glycogen phosphorylase in extracts of human brain

Monthly newsletter with information of interest to University Hospital and the Boston University Medical Campus

Optical and electrical characterization of poly-Si/SiOx contacts and their implications on solar cell design

Abstract The scope of this paper lies on the phenomenon of free-carrier absorption (FCA) in heavily phosphorus-doped poly-Si layers, applied at solar cells featuring poly-Si/SiO x passivating contacts at the rear. Firstly, FCA is investigated on test structures featuring poly-Si contacts of different thickness and doping level. Secondly, these passivating contacts are integrated into the rear of solar cells featuring a boron-diffused emitter at the front. The infrared (IR) response of the solar cells is analyzed and FCA losses are quantified. In agreement with theory, it is shown that J sc losses due to FCA increase with poly-Si doping level and thickness. For instance, a total J sc loss of ~0.5 mA/cm² is obtained for a 145 nm thick poly-Si layer with a doping concentration of 1.9x10 20 cm -3