Photoproduction of J/ψJ/\psi in association with a ccˉc\bar{c} pair

Based on the color-singlet model, we investigate the photoproduction of $J/\psi$ associated with a $c \bar{c}$ pair with all subprocesses including the direct, single-resolved, and double-resolved channels. The amplitude squared of these subprocesses are obtained analytically. By choosing corresponding parameters, we give theoretical predictions for the $J/\psi$ transverse momentum distributions both at the LEPII and at the future photon colliders for these subprocesses. The numerical results show that at the LEPII these processes can not give enough contributions to account for the experimental data, and it indicates that the color-octet mechanism may still be needed. At the photon collider with the laser back scattering photons, the resolved photon channe will dominate over the direct one in small and moderate $p_t$ regions with large $\sqrt{s}$. By measuring the $J/\psi$ production associated with a $c\bar{c}$ pair, this process can be separated from the inclusive $J/\psi$ production and may provide a new chance to test the color-singlet contributions.Comment: 16 pages, 7 figure

Ultraquantum magnetoresistance in Kramers Weyl semimetal candidate β\beta-Ag2Se

The topological semimetal $\beta$-Ag2Se features a Kramers Weyl node at the origin in momentum space and a quadruplet of spinless Weyl nodes, which are annihilated by spin-orbit coupling. We show that single crystalline $\beta$-Ag2Se manifests giant Shubnikov-de Haas oscillations in the longitudinal magnetoresistance which stem from a small electron pocket that can be driven beyond the quantum limit by a field less than 9 T. This small electron pocket is a remainder of the spin-orbit annihilatedWeyl nodes and thus encloses a Berry-phase structure. Moreover, we observed a negative longitudinal magnetoresistance when the magnetic field is beyond the quantum limit. Our experimental findings are complemented by thorough theoretical band structure analyses of this Kramers Weyl semimetal candidate, including first-principle calculations and an effective k*p model.Comment: A new version based on arXiv:1502.0232

QED contribution to the production of J/\psi+c\bar{c}+X at the Tevatron and LHC

We calculate \alpha^{2}\alpha_{s}^{2} order QED contribution to J/\psi production in pp(\bar{p})\to J/\psi+c\bar{c} color-singlet process at the Tevatron and LHC in the framework of non-relativistic QCD. The contribution of the interference between the \alpha^{2}\alpha_{s}^{2} QED and \alpha_{s}^{4} QCD is also taken into account. The J/\psi production associated with a charm quark pair could be a measurable signal at hadron collider experiment. Our calculations show that by including the QED contribution, the p_{t} distribution is enhanced by a factor of 1.5 (1.9) at the Tevatron (LHC) at p_{t}=50 (100) GeV. In addition, the polarization of J/\psi turns from unpolarized in all region to increasingly transverse when p_{t} becomes larger.Comment: 14 pages, 6 figures, version accepted for publication in Phys Rev

Muted change in Atlantic overturning circulation over some glacial-aged Heinrich events

Heinrich events—surges of icebergs into the North Atlantic Ocean—punctuated the last glacial period. The events are associated with millennial-scale cooling in the Northern Hemisphere. Fresh water from the melting icebergs is thought to have interrupted the Atlantic meridional overturning circulation, thus minimizing heat transport into the northern North Atlantic. The northward flow of warm water passes through the Florida Straits and is reflected in the distribution of seawater properties in this region. Here we investigate the northward flow through this region over the past 40,000 years using oxygen isotope measurements of benthic foraminifera from two cores on either side of the Florida Straits. These measurements allow us to estimate water density, which is related to flow through the thermal wind balance. We infer a substantial reduction of flow during Heinrich Event 1 and the Younger Dryas cooling, but little change during Heinrich Events 2 and 3, which occurred during an especially cold phase of the last glacial period. We speculate that because glacial circulation was already weakened before the onset of Heinrich Events 2 and 3, freshwater forcing had little additional effect. However, low-latitude climate perturbations were observed during all events. We therefore suggest that these perturbations may not have been directly caused by changes in heat transport associated with Atlantic overturning circulation as commonly assumed

Study on NNˉN\bar{N} SS-wave Elastic Cross Section and Possible Bound States Within a Constituent Quark Model

In the framework of a chiral constituent quark model, considering the contributions of $\pi$ annihilation and one-gluon annihilation, the proton-antiproton $S$-wave elastic scattering cross section experimental data can be reproduced by adjusting properly one-gluon annihilation coupling constant. Meanwhile, using the fixed model parameter, we do a dynamical calculation for all possible $S$-wave nucleon-antinucleon states, the results show that, there is no $S$-wave bound state as indicated by a strong enhancement at threshold of $p\bar{p}$ in $J/\psi$ and $B$ decays.Comment: 15 pages, 8 figure

Perceptions of Black Children's Narrative Language: A Mixed-Methods Study

Version: Accepted ManuscriptPurpose: In this mixed-methods study, we address two aims. First, we examine the impact of language variation on the ratings of children’s narrative language. Secondly, we identify participants' ideologies related to narrative language and language variation. Method: 40 adults listened to and rated six Black second-grade children on the quality of 12 narratives (six fictional, six personal). Adults then completed a quantitative survey and participated in a qualitative interview. Results: Findings indicated that adults rated students with less variation from mainstream American English (MAE) more highly than students with greater variation from MAE for fictional narratives but not for personal narratives. Personal narratives tended to be evaluated more favorably by parents than teachers. Black raters tended to assign higher ratings of narrative quality than did White raters. Thematic analysis and conversation analysis of qualitative interviews supported quantitative findings and provided pertinent information about participants' beliefs. Conclusion: Taken together, quantitative and qualitative results point to a shared language ideology among adult raters of variation from MAE being more acceptable in informal contexts, such as telling a story of personal experience, and less acceptable in more formal contexts, such as narrating a fictional story prompted by a picture sequence.The Ohio State University Cross-College Seed Gran

A Single Residue Mutation in the Gαq Subunit of the G Protein Complex Causes Blindness in Drosophila.

Heterotrimeric G proteins play central roles in many signaling pathways, including the phototransduction cascade in animals. However, the degree of involvement of the G protein subunit Gαq is not clear since animals with previously reported strong loss-of-function mutations remain responsive to light stimuli. We recovered a new allele of Gαq in Drosophila that abolishes light response in a conventional electroretinogram assay, and reduces sensitivity in whole-cell recordings of dissociated cells by at least five orders of magnitude. In addition, mutant eyes demonstrate a rapid rate of degeneration in the presence of light. Our new allele is likely the strongest hypomorph described to date. Interestingly, the mutant protein is produced in the eyes but carries a single amino acid change of a conserved hydrophobic residue that has been assigned to the interface of interaction between Gαq and its downstream effector, PLC. Our study has thus uncovered possibly the first point mutation that specifically affects this interaction in vivo