Estimation of Treatment Effects for Heterogeneous Matched Pairs Data with Probit Models

Estimating the effect of medical treatments on subject responses is one of the crucial problems in medical research. Matched-pairs designs are commonly implemented in the field of medical research to eliminate confounding and improve efficiency. In this article, new estimators of treatment effects for heterogeneous matched pairs data are proposed. Asymptotic properties of the proposed estimators are derived. Simulation studies show that the proposed estimators have some advantages over the famous Heckman's estimator and inverse probability weighted (IPW) estimator. We apply the proposed methodologies to a blood lead level data set and an acute leukaemia data set

Testing Einstein's Equivalence Principle with Fast Radio Bursts

The accuracy of Einstein's Equivalence Principle (EEP) can be tested with the observed time delays between correlated particles or photons that are emitted from astronomical sources. Assuming as a lower limit that the time delays are caused mainly by the gravitational potential of the Milky Way, we prove that fast radio bursts (FRBs) of cosmological origin can be used to constrain the EEP with high accuracy. Taking FRB 110220 and two possible FRB/gamma-ray burst (GRB) association systems (FRB/GRB 101011A and FRB/GRB 100704A) as examples, we obtain a strict upper limit on the differences of the parametrized post-Newtonian parameter $\gamma$ values as low as $\left[\gamma(1.23\; \rm GHz)-\gamma(1.45\; \rm GHz)\right]<4.36\times10^{-9}$. This provides the most stringent limit up to date on the EEP through the relative differential variations of the $\gamma$ parameter at radio energies, improving by 1 to 2 orders of magnitude the previous results at other energies based on supernova 1987A and GRBs.Comment: 5 Pages, 1 Figure. Published online in Physical Review Letters 23 December 2015. The letter has been highlighted by the editors as a Suggestion of Editor

Beam energy dependence of the relativistic retardation effects of electrical fields on the π−/π+\pi^{-}/\pi^{+} ratio in heavy-ion collisions

In this article we investigate the beam energy dependence of relativistic retardation effects of electrical fields on the single and double $\pi^{-}/\pi^{+}$ ratios in three heavy-ion reactions with an isospin- and momentum-dependent transport model IBUU11. With the beam energy increasing from 200 to 400 MeV/nucleon, effects of the relativistically retarded electrical fields on the $\pi^{-}/\pi^{+}$ ratio are found to increase gradually from negligibly to considerably significant as expectedly; it is however, the interesting observation is the relativistic retardation effects of electrical fields on the $\pi^{-}/\pi^{+}$ ratio are becoming gradually insignificant as the beam energy further increasing from 400 to 800 MeV/nucleon. Moreover, we also investigate the isospin dependence of relativistic retardation effects of electrical fields on the $\pi^{-}/\pi^{+}$ ratio in two isobar reaction systems of $^{96}$Ru+$^{96}$Ru and $^{96}$Zr+$^{96}$Zr at the beam energies from 200 to 800 MeV/nucleon. It is shown that the relativistic retardation effects of electrical fields on the $\pi^{-}/\pi^{+}$ ratio are independent of the isospin of reaction. Furthermore, we also examine the double $\pi^{-}/\pi^{+}$ ratio in reactions of $^{96}$Zr+$^{96}$Zr over $^{96}$Ru+$^{96}$Ru at the beam energies from 200 to 800 MeV/nucleon with the static field and retarded field, respectively. It is shown the double $\pi^{-}/\pi^{+}$ ratio from two reactions is still an effective observable of symmetry energy without the interference of electrical field due to using the relativistic calculation compared to the nonrelativistic calculation.Comment: 8 pages, 7 figures. Abbreviated abstract to meet the criterion of arXiv platform. Accepted for publication in Physical Review C. An extended but necessary complementary study to arXiv:1709.0912

Influence of neutron-skin thickness on π−/π+\pi^{-}/\pi^{+} ratio in Pb+Pb collisions

Within an isospin- and momentum-dependent transport model IBUU11 using as an input nucleon density profiles from Hartree-Fock calculations based on a modified Skyrme-like (MSL) model, we study the influence of the uncertainty of the neutron skin thickness on the $\pi^{-}/\pi^{+}$ ratio in both central and peripheral Pb+Pb collisions at beam energies of 400 MeV/nucleon and 1000 MeV/nucleon. Within the current experimental uncertainty range of neutron skin in $^{208}$Pb, while the neutron skin effect on the \rpi ratio is negligible in central reactions at both energies, it increases gradually with increasing impact parameter and becomes comparable with or even larger than the symmetry energy effect in peripheral collisions especially at 400 MeV/nucleon. Moreover, we found that while the \rpi ratio is larger with a softer \esym in central collisions, above certain impact parameters depending on the size of the neutron skin, a stiffer \esym can lead to a larger \rpi ratio as most of the pions are produced at densities below the saturation density in these peripheral reactions. Thus, a clear impact parameter selection is important to extract reliable information about the \esym at suprasaturation densities (size of neutron skin) from the $\pi^-/\pi^+$ ratio in central (peripheral) heavy-ion collisions.Comment: 8 pages including 9 figure

Tests of the Einstein Equivalence Principle using TeV Blazars

The observed time delays between different energy bands from TeV blazars provide a new interesting way of testing the Einstein Equivalence Principle (EEP). If the whole time delay is assumed to be dominated by the gravitational field of the Milky Way, the conservative upper limit on the EEP can be estimated. Here we show that the strict limits on the differences of the parameterized post-Newtonian parameter $\gamma$ values are $\gamma_{\rm TeV}-\gamma_{\rm keV}<3.86\times10^{-3}$ for Mrk 421 and $\gamma_{\rm TeV}-\gamma_{\rm keV}<4.43\times10^{-3}$ for Mrk 501, while expanding the scope of the tested EEP energy range out to the TeV--keV range for the first time. With the small time lag from the 0.2--0.8 TeV and $>0.8$ TeV light curves of PKS 2155-304, a much more severe constraint on $\gamma$ differences of $\sim10^{-6}$ can be achieved, although the energy difference is of order of $\sim$ TeV. Furthermore, we can combine these limits on the energy dependence of $\gamma$ with the bound on the absolute $\gamma$ value $\gamma-1\sim0.3\%$ from light deflection measurements at the optical (eV) bands, and conclude that this absolute bound on $\gamma$ can be extended from optical to TeV energies.Comment: 4 pages, accepted for publication in the Astrophysical Journal Letter

A Data Readout Approach for Physics Experiment

With the increasing physical event rate and number of electronic channels, traditional readout scheme meets the challenge of improving readout speed caused by the limited bandwidth of crate backplane. In this paper, a high-speed data readout method based on Ethernet is designed for each module to have capability of transmitting data to DAQ. Features of explicitly parallel data transmitting and distributed network architecture make the readout system has advantage of adapting varying requirements of particle physics experiments. Furthermore, to guarantee the readout performance and flexibility, a standalone embedded CPU system is utilized for network protocol stack processing. To receive customized data format and protocol from front-end electronics, a field programmable gate array (FPGA) is used for logic reconfiguration. To optimize the interface and improve the data swap speed between CPU and FPGA, a sophisticated method based on SRAM is presented in this paper. For the purpose of evaluating this high-speed readout method, a simplified readout module is designed and implemented. Test results show that this module can support up to 70Mbps data throughput from the readout module to DAQ smoothly

Hadronic production of WW and ZZ bosons at large transverse momentum

We introduce a modified factorization formalism in quantum chromodynamics for hadronic production of $W$ and $Z$ bosons at large transverse momentum $p_T$. When $p_T$ is much larger than the invariant mass $Q$ of the vector boson, this new factorization formalism systematically resums the large fragmentation logarithms, $\alpha_s^m\ln^m(p_T^2/Q^2)$, to all orders in the strong coupling $\alpha_s$. Using our modified factorization formalism, we calculate the next-to-leading order (NLO) predictions for $W$ and $Z$ boson production at high $p_T$ at the CERN Large Hadron Collider and at a future 100 TeV proton-proton collider. Our NLO results are about $5\%$ larger in normalization, and they show improved convergence and moderate reduction of the scale variation compared to the NLO predictions derived in a conventional fixed-order perturbative expansion.Comment: 14 pages, 12 figures; matches journal versio

Limits on the Neutrino Velocity, Lorentz Invariance, and the Weak Equivalence Principle with TeV Neutrinos from Gamma-Ray Bursts

Five TeV neutrino events weakly correlated with five gamma-ray bursts (GRBs) were detected recently by IceCube. This work is an attempt to show that if the GRB identifications are verified, the observed time delays between the TeV neutrinos and gamma-ray photons from GRBs provide attractive candidates for testing fundamental physics with high accuracy. Based on the assumed associations between the TeV neutrinos and GRBs, we find that the limiting velocity of the neutrinos is equal to that of photons to an accuracy of $\sim1.9\times10^{-15}-2.5\times10^{-18}$, which is about $10^{4}-10^{7}$ times better than the constraint obtained with the neutrino possibly from a blazar flare. In addition, we set the most stringent limits up to date on the energy scale of quantum gravity for both the linear and quadratic violations of Lorentz invariance, namely $E_{\rm QG, 1}>6.3\times10^{18}-1.5\times10^{21}$ GeV and $E_{\rm QG, 2}>2.0\times10^{11}-4.2\times10^{12}$ GeV, which are essentially as good as or are an improvement of one order of magnitude over the results previously obtained by the GeV photons of GRB 090510 and the PeV neutrino from a blazar flare. Assuming that the Shapiro time delay is caused by the gravitational potential of the Laniakea supercluster of galaxies, we also place the tightest limits to date on Einstein's weak equivalence principle through the relative differential variations of the parameterized post-Newtonian parameter $\gamma$ values for two different species of particles (i.e., neutrinos and photons), yielding $\Delta\gamma \sim 10^{-11}-10^{-13}$. However, it should be emphasized again that these limits here obtained are at best forecast of what could be achieved if the GRB/neutrino correlations would be finally confirmed.Comment: 11 Pages, 2 Tables. Accepted by Journal of Cosmology and Astroparticle Physic

Nonlocal Double-Slit Interference with Pseudothermal Light

We perform a nonlocal double-slit interference experiment with pseudothermal light. The experimental result exhibits a typical double-slit interference fringe in the intensity correlation measurement, in agreement with the theoretical analysis by means of the property of the second-order spatial correlation of field.Comment: 2 pages, 2 figure

Constraints on the Photon Mass with Fast Radio Bursts

Fast radio bursts (FRBs) are radio bursts characterized by millisecond durations, high Galactic latitude positions, and high dispersion measures. Very recently, the cosmological origin of FRB 150418 has been confirmed by \cite{kea16}, and FRBs are now strong competitors as cosmological probes. The simple sharp feature of the FRB signal is ideal for them to probe some of the fundamental laws of physics. Here we show that by analyzing the delay time between different frequencies, the FRB data can place stringent upper limits on the rest mass of the photon. For FRB 150418 at $z=0.492$, one can potentially reach $m_{\gamma} \leq 5.2 \times 10^{-47}$ g, which is $10^{20}$ times smaller than the rest mass of electron, and is about $10^3$ times smaller than that obtained using other astrophysical sources with the same method.Comment: 4 pages, 1 figure. Accepted for publication in ApJ Letter