Showing papers in "Progress of Theoretical and Experimental Physics in 2018"
290 citations
TL;DR: In this paper, the authors examined B-DECIGO's ability to measure binary parameters and assess to what extent multiband analysis could improve the accuracy of the binary parameters estimation.
Abstract: An evolving Japanese gravitational-wave (GW) mission in the decihertz band, B-DECIGO (DECihertz laser Interferometer Gravitational wave Observatory), will enable us to detect GW150914-like binary black holes, GW170817-like binary neutron stars, and intermediate-mass binary black holes out to cosmological distances. The B-DECIGO band slots in between the aLIGO–Virgo–KAGRA–IndIGO (hectohertz) and LISA (millihertz) bands for broader bandwidth; the sources described emit GWs for weeks to years across the multiple bands to accumulate high signal-to-noise ratios. This suggests the possibility that joint detection would greatly improve the parameter estimation of the binaries. We examine B-DECIGO’s ability to measure binary parameters and assess to what extent multiband analysis could improve such measurement. Using non-precessing post-Newtonian waveforms with the Fisher matrix approach, we find for systems like GW150914 and GW170817 that B-DECIGO can measure the mass ratio to within $$< 0.1\%$$, the individual black-hole spins to within $$< 10\%$$, and the coalescence time to within $$< 5\,$$s about a week before alerting aLIGO and electromagnetic facilities. Prior information from B-DECIGO for aLIGO can further reduce the uncertainty in the measurement of, e.g., certain neutron star tidally induced deformations by a factor of $$\sim$$6, and potentially determine the spin-induced neutron star quadrupole moment. Joint LISA and B-DECIGO measurement will also be able to recover the masses and spins of intermediate-mass binary black holes at percent-level precision. However, there will be a large systematic bias in these results due to post-Newtonian approximation of exact GW signals.
111 citations
TL;DR: In this paper, a new plausible estimate for the primordial black hole abundance based on peak theory is provided, where the curvature perturbation is given as a random Gaussian field with the power spectrum characterized by a single scale.
Abstract: The production rate of primordial black holes (PBHs) is often calculated by considering a nearly Gaussian distribution of cosmological perturbations, and assuming that black holes will form in regions where the amplitude of such perturbations exceeds a certain threshold. A threshold |$\zeta_{\rm th}$| for the curvature perturbation is somewhat inappropriate for this purpose, because it depends significantly on environmental effects, not essential to the local dynamics. By contrast, a threshold |$\delta_{\rm th}$| for the density perturbation at horizon crossing seems to provide a more robust criterion. On the other hand, the density perturbation is known to be bounded above by a maximum limit |$\delta_{\rm max}$| at the horizon entry and, given that |$\delta_{\rm th}$| is comparable to |$\delta_{\rm max}$|, the density perturbation will be far from Gaussian near or above the threshold. In this paper, we provide a new plausible estimate for the primordial black hole abundance based on peak theory. In our approach, we assume that the curvature perturbation is given as a random Gaussian field with the power spectrum characterized by a single scale, while an optimized criterion for PBH formation is imposed, based on the locally averaged density perturbation around the nearly spherically symmetric high peaks. Both variables are related by the full non-linear expression derived in the long-wavelength approximation of general relativity. We do not introduce a window function, which is usually introduced to obtain the scale dependence of the spectrum. The scale of the inhomogeneity is introduced as a random variable in the peak theory, and the scale-dependent PBH fraction is automatically induced. We find that the mass spectrum is shifted to larger mass scales by one order of magnitude or so, compared to a conventional calculation. The abundance of PBHs becomes significantly larger than the conventional one, by many orders of magnitude, mainly due to the optimized criterion for PBH formation and the removal of the suppression associated with a window function.
109 citations
TL;DR: In this article, the authors conducted sensitivity studies on an alternative configuration of the Hyper-Kamiokande experiment by locating the 2nd HK detector in Korea at $\sim$1100$-\ $1300 km baseline.
Abstract: We have conducted sensitivity studies on an alternative configuration of the Hyper-Kamiokande experiment by locating the 2nd Hyper-Kamiokande detector in Korea at $\sim$1100$-\ $1300 km baseline. Having two detectors at different baselines improves sensitivity to leptonic CP violation, neutrino mass ordering as well as nonstandard neutrino interactions. There are several candidate sites in Korea with greater than 1 km high mountains ranged at an 1$-$3 degree off-axis angle. Thanks to larger overburden of the candidate sites in Korea, low energy physics, such as solar and supernova neutrino physics as well as dark matter search, is expected to be improved. In this paper sensitivity studies on the CP violation phase and neutrino mass ordering are performed using current T2K systematic uncertainties in most cases. We plan to improve our sensitivity studies in the near future with better estimation of our systematic uncertainties.
95 citations
TL;DR: In this paper, the major construction and initial phase operation of a second-generation gravitational-wave detector, KAGRA, has been completed and the entire 3 km detector is installed underground in a mine in order to be isolated from background seismic vibrations on the surface.
Abstract: The major construction and initial-phase operation of a second-generation gravitational-wave detector, KAGRA, has been completed. The entire 3 km detector is installed underground in a mine in order to be isolated from background seismic vibrations on the surface. This allows us to achieve a good sensitivity at low frequencies and high stability of the detector. Bare-bones equipment for the interferometer operation has been installed and the first test run was accomplished in March and April of 2016 with a rather simple configuration. The initial configuration of KAGRA is called iKAGRA. In this paper, we summarize the construction of KAGRA, including a study of the advantages and challenges of building an underground detector, and the operation of the iKAGRA interferometer together with the geophysics interferometer that has been constructed in the same tunnel.
91 citations
TL;DR: In this article, a relativistic jet from a neutron star merger was modeled as a cocoon with an isotropic energy, opening angle, and viewing angle, which is consistent with the observations in a unified fashion.
Abstract: Gravitational waves from a merger of two neutron stars (NSs) were discovered for the first time in GW170817, together with diverse electromagnetic (EM) counterparts. To make constraints on a relativistic jet from the NS merger, we calculate the EM signals in (1) the short gamma-ray burst sGRB 170817A from an off-axis jet, (2) the optical-infrared macronova (or kilonova), especially the blue macronova, from a jet-powered cocoon, and (3) the X-ray and radio afterglows from the interaction between the jet and interstellar medium. We find that a typical sGRB jet is consistent with these observations, and there is a parameter space to explain all the observations in a unified fashion with an isotropic energy $\sim 10^{51}$-$10^{52}$ erg, opening angle $\sim 20^{\circ}$, and viewing angle $\sim 30^{\circ}$. The off-axis emission is less de-beamed than the point-source case because the viewing angle is comparable to the opening angle. We also analytically show that the jet energy accelerates a fair fraction of the merger ejecta to a sub-relativistic velocity $\sim 0.3$-$0.4$c as a cocoon in a wide parameter range. The ambient density might be low $\sim 10^{-3}$-$10^{-6}$ cm$^{-3}$, which can be tested by future observations of radio flares and X-ray remnants.
90 citations
TL;DR: In this article, the authors present a straightforward approach to calculate the partition function on various manifolds and ground state degeneracy (GSD), mainly based on continuum/cochain topological quantum field theories (TQFTs), in any dimension.
Abstract: Distinct quantum vacua of topologically ordered states can be tunneled into each other via extended operators. The possible applications include condensed matter and quantum cosmology. We present a straightforward approach to calculate the partition function on various manifolds and ground state degeneracy (GSD), mainly based on continuum/cochain topological quantum field theories (TQFTs), in any dimension. This information can be related to the counting of extended operators of bosonic/fermionic TQFTs. On the lattice scale, anyonic particles/strings live at the ends of line/surface operators. Certain systems in different dimensions are related to each other through dimensional reduction schemes, analogous to (de)categorification. Examples include spin TQFTs derived from gauging the interacting fermionic symmetry-protected topological states (with fermion parity $\mathbb{Z}_2^f$) of symmetry groups $\mathbb{Z}_4\times \mathbb{Z}_2$ and $(\mathbb{Z}_4)^2$ in 3+1D, also $\mathbb{Z}_2$ and $(\mathbb{Z}_2)^2$ in 2+1D. Gauging the last three cases begets non-Abelian spin TQFTs (fermionic topological order). We consider situations where a TQFT lives on (1) a closed spacetime or (2) a spacetime with a boundary, such that the bulk and boundary are fully gapped and short- or long-range entangled (SRE/LRE). Anyonic excitations can be deconfined on the boundary. We introduce new exotic topological interfaces on which neither particle nor string excitations alone condense, but only fuzzy-composite objects of extended operators can end (e.g., a string-like composite object formed by a set of particles can end on a special 2+1D boundary of 3+1D bulk). We explore the relations between group extension constructions and partially breaking constructions (e.g., 0-form/higher-form/“composite” breaking) of topological boundaries, after gauging. We comment on the implications of entanglement entropy for some such LRE systems
81 citations
TL;DR: In this article, the entanglement of purification for two-dimensional holographic CFT can be obtained from conformal blocks with internal twist operators, and the authors apply it to bipartite mixed states dual to subregion of AdS${}_3$ and the static BTZ blackhole geometries.
Abstract: We argue that the entanglement of purification for two dimensional holographic CFT can be obtained from conformal blocks with internal twist operators. First, we explain our formula from the view point of tensor network model of holography. Then, we apply it to bipartite mixed states dual to subregion of AdS${}_3$ and the static BTZ blackhole geometries. The formula in CFT agrees with the entanglement wedge cross section in the bulk, which has been recently conjectured to be equivalent to the entanglement of purification.
74 citations
TL;DR: In this paper, the authors presented results of new field-theoretic simulation of cosmological axion strings, which are eight times longer than previous ones, enabling them to monitor a variety of quantities characterizing the dynamics of the physical string network for the longest term ever.
Abstract: We present results of new field-theoretic simulation of cosmological axion strings, which are eight times longer than previous ones. We have upgraded our simulation of physical strings in Hiramatsu et al. (2011) in terms of the number of grids as well as the suite of analysis methods. These improvements enable us to monitor a variety of quantities characterizing the dynamics of the physical string network for the longest term ever. Our extended simulations have revealed that global strings do not evolve according to the scaling solution but its scaling parameter, or the number of long strings per horizon, increases logarithmically in time. In addition, we have also found that the scaling parameter shows nontrivial dependence on the breaking scale of the Peccei-Quinn symmetry.
69 citations
TL;DR: In this paper, it was shown that a self-duality group in quantum field theory can have anomalies, and a simple method to determine the anomaly when the 4D theory is obtained by compactifying a 6D theory on a Riemann surface in terms of the anomaly polynomial of the parent 6D theories was proposed.
Abstract: A self-duality group $${\mathcal{G}}$$ in quantum field theory can have anomalies. In that case, the space of ordinary coupling constants $${\mathcal{M}}$$ can be extended to include the space $${\cal F}$$ of coefficients of counterterms in background fields. The extended space $${\mathcal{N}}$$ forms a bundle over $${\mathcal{M}}$$ with fiber $${\cal F}$$, and the topology of the bundle is determined by the anomaly. For example, the $${\mathcal{G}}=SL(2,{\mathbb{Z}})$$ duality of the 4D Maxwell theory has an anomaly, and the space $${\cal F}={\mathbb{S}}^1$$ for the gravitational theta angle is nontrivially fibered over $${\cal M}={\mathbb{H}}/SL(2,{\mathbb{Z}})$$. We will explain a simple method to determine the anomaly when the 4D theory is obtained by compactifying a 6D theory on a Riemann surface in terms of the anomaly polynomial of the parent 6D theory. Our observations resolve an apparent contradiction associated with the global structure of the Kahler potential on the space of exactly marginal couplings of supersymmetric theories.
54 citations
TL;DR: In this article, a feed-forward neural network was proposed to solve the sign problem in the 2D complex ρ-phi-4 system with finite chemical potential, where the variables of integration are complexified and the integration path is optimized in the complexified space by minimizing the cost function.
Abstract: We introduce the feedforward neural network to attack the sign problem via the path optimization method. The variables of integration are complexified and the integration path is optimized in the complexified space by minimizing the cost function, which reflects the seriousness of the sign problem. For the preparation and optimization of the integral path in multi-dimensional systems, we utilize the feedforward neural network. We examine the validity and usefulness of the method in the 2D complex $\lambda \phi^4$ theory at finite chemical potential as an example of the quantum field theory with the sign problem. We show that the average phase factor is significantly enhanced after the optimization and then we can safely perform the hybrid Monte Carlo method.
TL;DR: In this article, it was shown that the scalar-tensor theory and gravity are equivalent at the quantum one-loop level on shell in arbitrary dimensions in the Jordan and Einstein frames.
Abstract: The $f(R)$ gravity and scalar-tensor theory are known to be equivalent at the classical level. We study if this equivalence is valid at the quantum level. There are two descriptions of the scalar-tensor theory in the Jordan and Einstein frames. It is shown that these three formulations of the theories give the same determinant or effective action on shell, and thus they are equivalent at the quantum one-loop level on shell in arbitrary dimensions. We also compute the one-loop divergence in $f(R)$ gravity.
TL;DR: In this paper, the effects of the first-order correction of entropy, caused by thermal fluctuation, on the thermodynamics of charged black holes in gravity's rainbow will be discussed, and it is shown that such correction has profound contributions to high energy limit of thermodynamical quantities, stability conditions of the black holes and interestingly has no effect on thermodynamic phase transitions.
Abstract: Quantum fluctuation effects have an irrefutable role in high energy physics. Such fluctuation can be often regarded as a correction of infrared (IR) limit. In this paper, the effects of the first-order correction of entropy, caused by thermal fluctuation, on the thermodynamics of charged black holes in gravity's rainbow will be discussed. It will be shown that such correction has profound contributions to high energy limit of thermodynamical quantities, stability conditions of the black holes and interestingly has no effect on thermodynamical phase transitions. The coupling between gravity's rainbow and the first-order correction will be addressed. In addition, the measurement of entropy as a function of fluctuation of temperature will be done and it will be shown that de Sitter (dS) case enforces an upper limit on the values of temperature and produces cyclic like diagrams. While for the anti-de Sitter (AdS) case, a lower limit on the entropy is provided and although for special cases a cyclic like behavior could be observed, no upper or lower limit exists for the temperature. In addition, a comparison between non-correction and correction included cases on the thermodynamical properties of solutions will also be discussed and the effects of the first-order correction will be highlighted. It will be shown that the first-order correction provides the solutions with larger classes of thermal stability conditions which may result into existence of a larger number of thermodynamical structures for the black holes.
University of Tokyo1, Université Paris-Saclay2, Kyushu University3, Oak Ridge National Laboratory4, Korea Research Institute of Standards and Science5, Kyungpook National University6, Kyoto University7, Toho University8, University of Miyazaki9, Osaka University10, Technische Universität Darmstadt11, National Autonomous University of Mexico12, Tohoku University13
TL;DR: In this paper, the dependence of the singleparticle strength on the difference between proton and neutron separation energies is studied for oxygen isotopes in a wide range of isospins.
Abstract: The dependence of the single-particle strength on the difference between proton and neutron separation energies is studied for oxygen isotopes in a wide range of isospins. The cross sections of the quasi-free (p, 2p) reaction on 14,16,18,22,24O were measured at intermediate energies. The measured cross sections are compared to predictions based on the distorted wave impulse approximation and shell-model psd valence-space spectroscopic factors. The reduction factors, which are the ratio of the experimental cross sections to the theoretical predictions, show no apparent dependence on the proton–neutron separation energy difference. The result is compatible with the result of the (e, e p) reaction on stable targets and with the predictions of recent ab initio calculations.
TL;DR: In this article, the moduli of elliptic K3 surfaces with a section with the $ADE$ rank 17 were studied. And the authors investigated the gauge symmetries in F-theory compactifications on attractive K3 surface which correspond to such special points in the modulus times a K3surface.
Abstract: We study the moduli of elliptic K3 surfaces with a section with the $ADE$ rank 17. While the Picard number of a generic K3 surface in such moduli space is 19, the Picard number is enhanced to 20 at special points in the moduli. K3 surfaces become attractive K3 surfaces at these points. Either of the following two situations occurs at such special points: i) the Mordell-Weil rank of an elliptic K3 surface is enhanced, or ii) the gauge symmetry is enhanced. The first case i) is related to the appearance of a $U(1)$ gauge symmetry. In this note, we construct the moduli of K3 surfaces with $ADE$ types $E_7 D_{10}$ and $A_{17}$. We determine some of the special points at which K3 surfaces become attractive in the moduli of K3 surfaces with $ADE$ types $E_7 D_{10}$ and $A_{17}$. We investigate the gauge symmetries in F-theory compactifications on attractive K3 surfaces which correspond to such special points in the moduli times a K3 surface. $U(1)$ gauge symmetry arises in some F-theory compactifications.
TL;DR: In this paper, the conditions to preserve part of the supersymmetry of Yang-Mills theory with couplings and masses depending on space-time were derived and a lot of solutions of these conditions were found.
Abstract: We study deformations of ${\cal N}=4$ supersymmetric Yang-Mills theory with couplings and masses depending on space-time. The conditions to preserve part of the supersymmetry are derived and a lot of solutions of these conditions are found. The main example is the case with $ISO(1,1)\times SO(3)\times SO(3)$ symmetry, in which couplings, as well as masses and the theta parameter, can depend on two spatial coordinates. In the case $ISO(1,1)$ is enhanced to $ISO(1,2)$, it reproduces the supersymmetric Janus configuration found by Gaiotto and Witten. When $SO(3)\times SO(3)$ is enhanced to $SO(6)$, it agrees with the world-volume theory of D3-branes embedded in F-theory (a background with 7-branes in type IIB string theory). We also find the general solution of the supersymmetry conditions for the cases with $ISO(1,1)\times SO(2)\times SO(4)$ symmetry. The cases with time dependent couplings and/or masses are also considered.
TL;DR: In this paper, the mass spectra of the standard model particles are reproduced in the SO(11)$ gauge-Higgs grand unification in the six-dimensional warped space without introducing exotic light fermions.
Abstract: The mass spectra of the standard model particles are reproduced in the $SO(11)$ gauge-Higgs grand unification in the six-dimensional warped space without introducing exotic light fermions. Light neutrino masses are explained by the gauge-Higgs seesaw mechanism. We evaluate the effective potential of the 4d Higgs boson appearing as a fluctuation mode of the Aharonov-Bohm phase $\theta_H$ in the extra-dimensioal space, and show that the dynamical electroweak symmetry breaking takes place with the Higgs boson mass $m_H \sim 125\,$GeV and $\theta_H \sim 0.1$. The Kaluza-Klein mass scale in the fifth dimension is approximately given by $m_{\rm KK} \sim 1.230\,{\rm TeV}/\sin \theta_H$.
TL;DR: Sakatani and Uehara as discussed by the authors developed the self-duality relation known in the double sigma model is naturally generalized to M-branes, where the Hodge star operator is defined with the familiar M5-brane metric while the $$\eta$$-form contains the selfdual three-form field strength.
Abstract: We develop the M-brane actions proposed in Y. Sakatani and S. Uehara, arXiv:1607.04265, by using $$\eta$$-symbols determined in Y. Sakatani and S. Uehara, arXiv:1708.06342. Introducing $$\eta$$-forms that are defined with the $$\eta$$-symbols, we present $$U$$-duality-covariant M-brane actions which describe the known brane worldvolume theories for M$$p$$-branes with $$p=0,2,5$$. We show that the self-duality relation known in the double sigma model is naturally generalized to M-branes. In particular, for an M5-brane, the self-duality relation is nontrivially realized, where the Hodge star operator is defined with the familiar M5-brane metric while the $$\eta$$-form contains the self-dual three-form field strength. The action for a Kaluza–Klein monopole is also partially reproduced. Moreover, we explain how to treat type IIB branes in our general formalism. As a demonstration, we reproduce the known action for a $$(p,q)$$-string.
TL;DR: In this article, the determinant method in the conformal bootstrap is applied for the critical phenomena of a single polymer in arbitrary $D$ dimensions, and the scale dimensions of the polymer and the branched polymer are obtained from the small determinants.
Abstract: The determinant method in the conformal bootstrap is applied for the critical phenomena of a single polymer in arbitrary $D$ dimensions. The scale dimensions (critical exponents) of the polymer ($2< D \le 4$) and the branched polymer ($3 < D \le 8$) are obtained from the small determinants. It is known that the dimensional reduction of the branched polymer in $D$ dimensions to Yang-Lee edge singularity in $D$-$2$ dimensions holds exactly. We examine this equivalence by the small determinant method.
TL;DR: In this article, the Yang-Lee edge singularity is investigated by the determinant method of the conformal field theory and the critical dimension Dc, for which the scale dimension of scalar Delta_phi is vanishing, is discussed.
Abstract: The Yang-Lee edge singularity is investigated by the determinant method of the conformal field theory. The critical dimension Dc, for which the scale dimension of scalar Delta_phi is vanishing, is discussed by this determinant method. The result is incorporated in the Pade analysis of epsilon expansion, which leads to an estimation of the value Delta_phi between three and six dimensions. The structure of the minors is viewed from the fixed points.
TL;DR: In this paper, it was shown that an induced metric defined from the flowed field generally corresponds to the quantum information metric, called the Bures or Helstrom metric, if the flow field is normalized appropriately, and that the induced metric computed explicitly with the free flow equation always becomes the AdS metric when the theory is conformal.
Abstract: We argue that the Anti-de-Sitter (AdS) geometry in d+1 dimensions naturally emerges from an arbitrary conformal field theory in d dimensions using the free flow equation. We first show that an induced metric defined from the flowed field generally corresponds to the quantum information metric, called the Bures or Helstrom metric, if the flowed field is normalized appropriately. We next verify that the induced metric computed explicitly with the free flow equation always becomes the AdS metric when the theory is conformal. We finally prove that the conformal symmetry in d dimensions converts to the AdS isometry in d+1 dimensions after d dimensional quantum averaging. This guarantees the emergence of AdS geometry without explicit calculation.
TL;DR: In this article, the topological susceptibility of lattice QCD with dynamical quark flavors described by the Mobius domain wall fermion was computed and shown to be consistent with the prediction of chiral perturbation theory.
Abstract: We compute the topological susceptibility $\\chi_t$ of lattice QCD with $2+1$ dynamical quark flavors described by the Mobius domain wall fermion. Violation of chiral symmetry as measured by the residual mass is kept at $\\sim$1 MeV or smaller. We measure the fluctuation of the topological charge density in a `slab' sub-volume of the simulated lattice using the method proposed by Bietenholz {\\it et al.} The quark mass dependence of $\\chi_t$ is consistent with the prediction of chiral perturbation theory, from which the chiral condensate is extracted as $\\Sigma^{\\overline{\\rm MS}} (\\mbox{2GeV}) = [274(13)(29)\\mbox{MeV}]^3$, where the first error is statistical and the second one is systematic. Combining the results for the pion mass $M_\\pi$ and decay constant $F_\\pi$, we obtain $\\chi_t = 0.229(03)(13)M_\\pi^2F_\\pi^2$ at the physical point.
TL;DR: In this article, conformal quantum mechanics (CQM) from the perspective of sine-square deformation (SSD) and the entanglement Hamiltonian is revisited.
Abstract: We revisit conformal quantum mechanics (CQM) from the perspective of sine-square deformation (SSD) and the entanglement Hamiltonian. The operators that correspond to SSD and the entanglement Hamiltonian are identified. Thus, the nature of SSD and entanglement can be discussed in a much simpler CQM setting than higher-dimensional field theories.
TL;DR: In this paper, the authors revisited the NuFIT 3.2 model for leptons and neutrinos in next-to-leading-order operators and showed that the model is consistent with experimental data only for the normal hierarchy of neutrino masses.
Abstract: We revisit the $$A_4$$ model for leptons in light of the new result of NuFIT 3.2. We introduce a new flavon $$\eta$$ transforming as an $$A_4$$ singlet $$1'$$ or $$1''$$, which couples to both charged leptons and neutrinos in next-to-leading-order operators. The model consists of five parameters: the lightest neutrino mass $$m_1$$, the vacuum expectation value of $$\eta$$, and three CP-violating phases after inputting the experimental values of $$\Delta m_{\rm atm}^2$$ and $$\Delta m_{\rm sol}^2$$. The model with the $$1''$$ singlet flavon gives the prediction of $$\sin^2 \theta_{12}$$ around the best fit of NuFIT 3.2 while staying near the maximal mixing of $$\theta_{23}$$. Inputting the experimental mixing angles with the $$1\,\sigma$$ error-bar, the Dirac CP-violating phase is clearly predicted to be $$|\delta_\text{CP}|=50$$–$$120^\circ$$, which will be tested by the precise observed value in the future. In order to get the best-fit value $$\sin^2\theta_{23}=0.538$$, the sum of three neutrino masses is predicted to be larger than $$90$$meV. The cosmological observation for the sum of the neutrino masses will also provide a crucial test of our predictions. It is remarked that the model is consistent with the experimental data only for the normal hierarchy of neutrino masses.
TL;DR: In this article, a variational method for treating short-range repulsion of bare nuclear force for nuclei in antisymmetrized molecular dynamics (AMD) is proposed.
Abstract: We propose a new variational method for treating short-range repulsion of bare nuclear force for nuclei in antisymmetrized molecular dynamics (AMD). In AMD, the short-range correlation is described in terms of large imaginary centroids of Gaussian wave packets of nucleon pairs in opposite signs, causing high-momentum components in nucleon pair. We superpose these AMD basis states and name this method "high-momentum AMD" (HM-AMD), which is capable of describing strong tensor correlation (Prog. Theor. Exp. Phys. (2017) 111D01). In this paper, we extend HM-AMD by including up to two kinds of nucleon pairs in each AMD basis state utilizing the cluster expansion, which produces many-body correlations involving high-momentum components. We investigate how much HM-AMD describes the short-range correlation by showing the results for $^3$H using the Argonne V4$^\prime$ central potential. It is found that HM-AMD reproduces the results of few-body calculations and also the tensor-optimized AMD. This means that HM-AMD is a powerful approach to describe the short-range correlation in nuclei. In HM-AMD, momentum directions of nucleon pairs isotropically contribute to the short-range correlation, which is different from the tensor correlation.
TL;DR: In this paper, the authors proposed a new high-count-rate detector for future spallation neutron sources where large area and high-efficiency (amp;gt;50%) detectors are envisaged.
Abstract: Newhigh-count-rate detectors are required for future spallation neutron sources where large-area and high-efficiency (amp;gt;50%) detectors are envisaged. In this framework, Gas Electron Multiplier ...
TL;DR: In this paper, the authors studied the axion mass in a range from 10−13 to 10−3 in the presence of the Chern-Simons term and the velocity of light in the background of axion dark matter.
Abstract: It is widely believed that axions are ubiquitous in string theory and could be the dark matter. The peculiar features of the axion dark matter are coherent oscillations and a coupling to the electromagnetic field through the Chern-Simons term. In this paper, we study consequences of these two features of the axion with the mass in a range from $10^{-13}\,{\rm eV}$ to $10^{3}\,{\rm eV}$. First, we study the parametric resonance of electromagnetic waves induced by the coherent oscillation of the axion. As a result of the resonance, the amplitude of the electromagnetic waves is enhanced and the circularly polarized monochromatic waves will be generated. Second, we study the velocity of light in the background of the axion dark matter. In the presence of the Chern-Simons term, the dispersion relation is modified and the speed of light will oscillate in time. It turns out that the change of speed of light would be difficult to observe. We argue that the future radio wave observations of the resonance can give rise to a stronger constraint on the coupling constant and/or the density of the axion dark matter.