Beam polarization effects on top-pair production at the ILC

Full one-loop electroweak-corrections for an $e^-e^+\rightarrow t \bar{t}$ process associated with sequential $t\rightarrow b \mu\nu_\mu$ decay are discussed. At the one-loop level, the spin-polarization effects of the initial electron and positron beams are included in the total and differential cross sections. A narrow-width approximation is used to treat the top-quark production and decay while including full spin correlations between them. We observed that the radiative corrections due to the weak interaction have a large polarization dependence on both the total and differential cross sections. Therefore, experimental observables that depend on angular distributions such as the forward-backward asymmetry of the top production angle must be treated carefully including radiative corrections. We also observed that the energy distribution of bottom quarks is majorly affected by the radiative corrections.Comment: 15 pages, 8 figure

The Student Experience of Higher Education during the COVID-19 Pandemic: How Class and Race Shape Socially Distanced Learning at a Public University

While prior research has examined trends toward growing uncertainty and precarity for young adults within the economy and higher education, the COVID-19 pandemic appears to be exacerbating these existing inequalities and risks. Drawing from 30 semi-structured in-depth interviews with college students at a large Southern and urban public university, this study examines how the COVID-19 pandemic is affecting students’ learning experiences, and how those experiences are differentially shaped, in turn, by their class and race. This exploratory research illuminates our understanding of the multiple mechanisms by which the COVID-19 pandemic is shaping existing inequalities in the higher education system, mostly by worsening the outcomes of less advantaged students. The findings reveal that less advantaged students, particularly low-income students of color, are facing greater difficulties during the pandemic in terms of obtaining reliable Internet access, reliable computers, and a reliable space to do work along with coping with related mental health impacts from the pandemic and also the national racial reckoning that took place over the summer after the deaths of George Floyd, Ahmaud Arbery, and Breonna Taylor

Negative Refraction of Excitations in the Bose-Hubbard Model

Ultracold atoms in optical lattices provide a unique opportunity to study Bose- Hubbard physics. In this work we show that by considering a spatially varying onsite interaction it is possible to manipulate the motion of excitations above the Mott phase in a Bose-Hubbard system. Specifically, we show that it is possible to "engineer" regimes where excitations will negatively refract, facilitating the construction of a flat lens.Comment: 6 pages, 4 figure

FeCr₂S₄ in magnetic fields: possible evidence for a multiferroic ground state.

We report on neutron diffraction, thermal expansion, magnetostriction, dielectric, and specific heat measurements on polycrystalline FeCr2S4 in external magnetic fields. The ferrimagnetic ordering temperatures TC ≈ 170 K and the transition at TOO ≈ 10 K, which has been associated with orbital ordering, are only weakly shifted in magnetic fields up to 9 T. The cubic lattice parameter is found to decrease when entering the state below TOO. The magnetic moments of the Cr- and Fe-ions are reduced from the spin-only values throughout the magnetically ordered regime, but approach the spin-only values for fields >5.5 T. Thermal expansion in magnetic fields and magnetostriction experiments indicate a contraction of the sample below about 60 K. Below TOO this contraction is followed by a moderate expansion of the sample for fields larger than ~4.5 T. The transition at TOO is accompanied by an anomaly in the dielectric constant. The dielectric constant depends on both the strength and orientation of the external magnetic field with respect to the applied electric field for T < TOO. A linear correlation of the magnetic-field-induced change of the dielectric constant and the magnetic-field dependent magnetization is observed. This behaviour is consistent with the existence of a ferroelectric polarization and a multiferroic ground state below 10 K

Gratitude for Better or Worse: Differential Predictors and Affective Outcomes of State Gratitude in Positive and Negative Contexts

Whereas past studies primarily examined state-level gratitude measured across long periods of time and in the context of positive events, this study assessed situational predictors of state gratitude and its affective outcomes in the context of specific positive and negative naturalistic events. Across seven weeks, 147 undergraduates recorded best and worst weekly events, depressive symptoms, as well as gratitude and positive affect (PA) anchored to those events. Independent raters coded events as dependent or independent of participants’ agency and interpersonal or noninterpersonal. Multilevel models showed there was a significant interaction between agency and interpersonal status for positive events, and simple effects tests indicated participants reported higher levels of gratitude for independent-interpersonal events compared to other potential event types. Unexpectedly, participants also reported higher gratitude for dependent events if they were interpersonal in nature. Negative event-anchored state gratitude was also higher for interpersonal events as indicated by a significant main effect. Lastly, within-person variability in event-anchored state gratitude was associated with higher state PA following both best and worst events, but only state gratitude anchored to best events was related to lower weekly depressive symptoms. Overall, results demonstrated that naturally occurring state gratitude for specific events was differentially impacted by situational factors, and that within-person variability in gratitude following both positive and negative events is related to positive affective outcomes

3D FEM to predict residual stresses of press-braked thin-walled steel sections

Cold-formed steel sections are normally produced by cold work manufacturing processes. The amount of cold work to form the sections may have induced residual stresses in the section especially in the area of bending. Hence, these cold work processes may have significant effects on the section behaviour and load-bearing capacity. There was a lack of studies in investigating the effects of residual stresses raised by press-braking operations unlike the roll-forming operation. Therefore, a 3D finite element simulation was employed to simulate this forming process. This study investigated the magnitude of the maximum residual stresses along the length of the corner region and through-thickness residual stress variations induced by the press-braking forming process. The study concluded that residual stresses are not linear longitudinally (along the corner region). Maximum residual stresses exist near the middle surface of the plate. The comparison of the 3D-FE results with the 2D-FE results illustrate that 3D-FE has a variation in transverse and longitudinal residual stresses along the plate length. In addition, 2D-FE results overestimate the residual stresses along the corner region

Life Isn\u27t Fair : Children Know What\u27s Fair, but Expect Groups to Behave Unfairly

Social mobility is partially based on access to economic and non-economic opportunities. Individuals from disadvantaged or minority groups often have difficulties with social mobility because they do not have equal access to opportunities. Early on, children develop the ability to form personal judgments about social groups and understand their own memberships within them (Patterson et al., 2016). Although children expect people to privilege their own group, they also value fairness (DeJesus, Rhodes, & Kinzler, 2013). Previous studies have focused on children’s understanding of resource distribution. In contrast, the current study examined what children think about opportunity distribution between majority and minority groups. Participants included 31 6- to 9-year-olds. When prompted to select new group members for an exclusive group, children were first asked who they expected the majority group to choose (between two majority members, a majority and a minority member, or two minority members). They were then asked who they thought were most fair for the majority group to choose. Children expected groups to distribute opportunities to majority members. However, they thought it was most fair for groups to provide opportunities to minority members. This understanding of opportunity distribution did not change between the two age groups (6-7s and 8-9s). These results suggested that children recognize what is equitable as well as the reality of opportunity distribution between majority and minority groups.https://ir.library.louisville.edu/uars/1058/thumbnail.jp