Search results for " asymmetry."
showing 7 items of 257 documents
Dark matter and baryogenesis in Higgs portal models
2016
This work focuses on two of the main issues in current understanding of particle physics described by the Standard Model. The Standard Model, despite of its success, is not complete. Existence of dark matter has been clearly verified, but its nature is unknown. Also, the baryon asymmetry in the Universe hints that the Standard Model has to be extended. In this thesis we study Higgs portal models which both contain dark matter candidates, and can provide for a successful production of the baryon asymmetry.
Comparing proton momentum distributions in A = 2 and 3 nuclei via 2H 3H and 3He (e,e′p) measurements
2019
We report the first measurement of the $(e,e'p)$ reaction cross-section ratios for Helium-3 ($^3$He), Tritium ($^3$H), and Deuterium ($d$). The measurement covered a missing momentum range of $40 \le p_{miss} \le 550$ MeV$/c$, at large momentum transfer ($\langle Q^2 \rangle \approx 1.9$ (GeV$/c$)$^2$) and $x_B>1$, which minimized contributions from non quasi-elastic (QE) reaction mechanisms. The data is compared with plane-wave impulse approximation (PWIA) calculations using realistic spectral functions and momentum distributions. The measured and PWIA-calculated cross-section ratios for $^3$He$/d$ and $^3$H$/d$ extend to just above the typical nucleon Fermi-momentum ($k_F \approx 250$ …
Can cystic lesions of the jaws be considered as the cause of mandibular asymmetry?
2021
The aim of this study is to investigate the presence of condylar and ramal asymmetry in patients with a cyst larger than 10 mm in the maxilla or mandible. Condylar and ramal asymmetry index measurements of 47 patients (mean age: 28.85 ± 15.348) in the study group and 40 patients in the control group (mean age: 33.73 ± 13.095) were performed using panoramic radiographs. The study group consists of patients with cysts larger than 10 mm in diameter in the maxilla or mandible. The control group consisted of patients with no radiolucent lesions and no history of trauma. The possible statistical difference between the groups was evaluated by the Mann-Whitney U test. No statistically significant d…
Assessment of Asymmetrical Lower Limb Loading in the Short-Track Speed Skaters
2023
Background. Short-track speed skaters who regularly participate in training are exposed to the occurrence of asymmetry in the lower limb loading. 
 Objective. The study aimed to assess the symmetry of the lower limb loading in short track skaters and the relationship between age, training experience and anthropometric variables and symmetry of lower limb loading.
 Methods. The examined group consisted of 20 short-track speed skaters (12 men and 8 women), and the control group comprised 28 university students (14 men and 14 women). Two scales were used to assess the symmetry of lower limb loading, and the lower limb's loading symmetry index (LSI) was calculated. 
 Results. In …
Biological adaptation in light of the Lewontin–Williams (a)symmetry
2022
Neo-Darwinism characterises biological adaptation as a one-sided process, in which organisms adapt to their environment but not vice versa. This asymmetric relationship – here called Williams’ asymmetry – is called into question by Niche Construction Theory, which emphasises that organisms and their environments often mutually affect each other. Here we clarify that Williams’ asymmetry is specifically concerned with (quasi-) directed modifications towards phenotypes that increase individual fitness. This directedness – which drives the adaptive fit between organism and environment – entails far more than the mere presence of cause-effect relationships. We argue that difficulties with invoki…
Nuclear Dependence of the Transverse-Single-Spin Asymmetry for Forward Neutron Production in Polarized p+A Collisions at √sNN = 200 GeV
2018
During 2015, the Relativistic Heavy Ion Collider (RHIC) provided collisions of transversely polarized protons with Au and Al nuclei for the first time, enabling the exploration of transverse-single-spin asymmetries with heavy nuclei. Large single-spin asymmetries in very forward neutron production have been previously observed in transversely polarized p + p collisions at RHIC, and the existing theoretical framework that was successful in describing the single-spin asymmetry in p + p collisions predicts only a moderate atomic-mass-number ( A ) dependence. In contrast, the asymmetries observed at RHIC in p + A collisions showed a surprisingly strong A dependence in inclusive forward neutron …
Measurement of parity-violating spin asymmetries in W± production at midrapidity in longitudinally polarized p+p collisions
2016
We present midrapidity measurements from the PHENIX experiment of large parity-violating singlespin asymmetries of high transverse momentum electrons and positrons from W =Z decays, produced in longitudinally polarized p þ p collisions at center of mass energies of ffiffi s p ¼ 500 and 510 GeV. These asymmetries allow direct access to the antiquark polarized parton distribution functions due to the parityviolating nature of the W-boson coupling to quarks and antiquarks. The results presented are based on data collected in 2011, 2012, and 2013 with an integrated luminosity of 240 pb−1, which exceeds previous PHENIX published results by a factor of more than 27. These high Q2 data probe the p…