Bulletin of the American Physical Society
Fall 2015 Joint Meeting of the Texas Section of the AAPT, Texas Section of the APS and Zone 13 of the Society of Physics Students
Volume 60, Number 15
Thursday–Saturday, October 29–31, 2015; Waco, Texas
Session N4: High Energy Physics III |
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Chair: Anzhong Wang, Baylor University Room: A.207 |
Saturday, October 31, 2015 10:30AM - 11:00AM |
N4.00001: Detecting quantum gravitational effects in the early universe?" Invited Speaker: Anzhong Wang I shall first give a brief introduction on the current development of observational cosmology and state clearly the need for accurate calculations of power spectra and spectral indices of Cosmic Microwave Background (CMB) radiation, after quantum gravitational effects in the early universe are taken into account. Then, I shall present the uniform approximation method developed recently by us, which is specially designed to investigate such effects with an upper bounds of errors less than 0.15 %. Applying it to loop quantum cosmology, I shall argue that the quantum gravitational effects can be well within the range of detectability of the forthcoming (such as, Stage IV) CMB experiments. [Preview Abstract] |
Saturday, October 31, 2015 11:00AM - 11:12AM |
N4.00002: Extrapolation Technique Pitfalls in Asymmetry Measurements at Colliders Katrina Colletti, David Toback, Jon Wilson, Ziqing Hong Asymmetry measurements are common in collider experiments and can sensitively probe particle properties. Typically, data can only be measured in a finite region covered by the detector, so an extrapolation from the visible asymmetry to the inclusive asymmetry is necessary. Often a constant multiplicative factor is more than adequate for the extrapolation and this factor can be readily determined using simulation methods. However, there is a potential, avoidable pitfall involved in the determination of this factor when the asymmetry in the simulated data sample is small. We find that, to obtain a reliable estimate of the extrapolation factor, the number of simulated events required rises as the inverse square of the simulated asymmetry, which can mean that an unexpectedly large sample size is required when determining its value. [Preview Abstract] |
Saturday, October 31, 2015 11:12AM - 11:24AM |
N4.00003: Simulating Neutron Interaction with Cryogenic Dark Matter Detectors Alex Jagrowski, Rob Agnese, Tarek Saab, Jonathen Settle The Super Cryogenic Dark Matter Search (SuperCDMS) is one of the experiments designed to directly detect dark matter in the form of weakly-interacting massive particles, or ``WIMPS''. The detectors used in this experiment are very sensitive at cryogenic temperatures and are designed to measure the recoil energy imparted to a nucleus in the detector due to collisions with WIMPs. These detectors have already achieved progressive improvements in detection technology; however, it remains unclear how the detectors will register interactions with WIMPS. Here we report on the use of Geant4, a Monte-Carlo framework, to simulate the SuperCDMS setup and its interaction with low-energy neutrons, which should closely approximate the response of the detector to WIMPs. Preliminary results of this simulation indicate a close match of the simulation to already-established physics for neutrons interactions with the materials in the simulation. This matching of the simulation to actual results suggests the future usefulness of the simulation for enabling a calibration of the detector with low-energy neutrons. [Preview Abstract] |
Saturday, October 31, 2015 11:24AM - 11:36AM |
N4.00004: Lifshitz solutions and the effects of high-order operators Xinwen Wang, Jie Yang, Miao Tian, Anzhong Wang, Yanbin Deng e study the effects of high-order operators on the nonrelativistic Lifshitz holography inthe framework of the Ho\v{r}ava-Lifshitz (HL) theory of gravity, which naturally contains high-order operatorsin order for the theory to be power-counting renormalizable, and provides an ideal place for such studies. Inparticular, we show that the Lifshitz spacetime is still a solution of the full theory of the HL gravity. Theeffects of the high-order operators on the spacetime itself is simply to shift the Lifshitz dynamical exponent. [Preview Abstract] |
Saturday, October 31, 2015 11:36AM - 11:48AM |
N4.00005: Charged Einstein-aether black holes and Smarr formula Chikun Ding, Anzhong Wang, Xinwen Wang In the framework of the Einstein-Maxwell-aether theory, we present two new classes of exact charged black hole solutions, which are asymptotically flat and possess the universal as well as Killing horizons. We also construct the Smarr formulas, and calculate the temperatures of the horizons, using the Smarr mass-area relation. We find that, in contrast to the neutral case, such obtained temperature is not proportional to its surface gravity at any of the two kinds of the horizons. Einstein-Maxwell-aether black holes with the cosmological constant and their topological cousins are also given. [Preview Abstract] |
Saturday, October 31, 2015 11:48AM - 12:00PM |
N4.00006: Quantization of 1+1 Dimensional Horava-Lifshitz Gravity Baofei Li, Anzhong Wang, Yumei Wu, Zhongchao Wu we study the quantization of the (1+1)-dimensional projectable Horava-Lifshitz gravity, and find that, when only gravity is present, the system can be quantized by following the standard Dirac quantization. The corresponding Hamilton can also be written in terms of a simple harmonic oscillator, where the expectation value of the gauge-invariant length operator defines the fundamental length of the system. When the gravity minimally couples to a scalar field, the momentum constraint can be solved explicitly only in the case where the fundamental variables are functions of time only. In this case, the coupled system can also be quantized by following the Dirac process. When the self-interaction of the scalar field vanishes, the corresponding Hamilton can be written in terms of two harmonic oscillators, one has positive energy, while the other has negative energy. A remarkable feature is that the space-time is well quantized, even when it is classically singular. [Preview Abstract] |
Saturday, October 31, 2015 12:00PM - 12:12PM |
N4.00007: Inflationary Spectra with quantum corrections in loop quantum cosmology Tao Zhu, Anzhong Wang, Gerald Cleaver, Klaus Kirsten, Qin Sheng, Qiang Wu Loop quantum cosmology (LQC) provides promising resolutions to the trans-Planckian issue and initial singularity arising in the inflationary models of general relativity. In general, LQC involves two types of quantum corrections, the holonomy and inverse-volume, to both of the cosmological background evolution and perturbations. In this work, using the uniform asymptotic approximations, we derive explicitly the observational quantities of the slow-roll inflation in the framework of LQC with these quantum corrections. We calculate the power spectra, spectral indices, and running of the spectral indices for both scalar and tensor perturbations, represent the most accurate results obtained so far in the literature. It is also shown that with the inverse-volume corrections, both scalar and tensor spectra exhibit a deviation from the usual shape at large scales. Then, using the recent released Planck data, we obtain new constraints on quantum gravitational effects from LQC corrections, and find that such effects could be within the detection of the forthcoming experiments. [Preview Abstract] |
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