54971266
Effects on the two-point correlation function from the coupling of quintessence to dark matter
We investigate the effects of the nonminimal coupling between the scalar field dark energy (quintessence) and the dark matter on the two-point correlation function. It is well known that this coupling shifts the turnover scale as well as suppresses the amplitude of the matter power spectrum. However, these effects are too small to be observed when we limit the coupling strength to be consistent with observations. Since the coupling of quintessence to baryons is strongly constrained, species-dependent coupling may arise. This results in a baryon bias that is different from unity. Thus, we investigate the correlation function in this coupled model. We are able to observe the enhancement of the baryon acoustic oscillation (BAO) peak due to the increasing bias factor of baryon from this species-dependent coupling. In order to avoid the damping effect of the BAO signature in the matter power spectrum due to nonlinear clustering, we consider the coupling effect on the BAO bump in the linear regime. This provides an alternative method to constrain the coupling of dark energy to dark matter.
117762235
Correct sub-horizon scales linear perturbation equation for general dark energy models
118495217
Evidence for departure from \Lambda CDM with LSS
We investigate the growth index parameter \gamma and the time variation of the gravitational constant G_{eff} by using the currently available growth function f(z) data at different redshifts, with and without scaling to the fiducial \Lambda CDM model. We inquire the four different models of \gamma including a constant \gamma. From a \chi^2 minimization, we constrain the parameter spaces of models and show that \Lambda CDM model is excluded by 1-\sigma level from current f(z) data. G_{eff} is different from the Newton's gravitational constant G_{N} in modified gravity theories and interestingly, the current data shows that G_{eff} \neq G_{N} at z \gtrsim 0.2 \sim 0.3 at 3-\sigma level. From these, we conclude that Einstein's General Relativity with \Lambda CDM is ruled out by 99% confidence level from large scale structure observations.
3165699
Growth index in an accelerating universe
We obtain the exact analytic form of growth index ($f = \Omega_{m}(a)^{\gamma}$) at present epoch in a flat universe for the general value of constant equation of state of dark energy $\omega_{de}$. For the cosmological constant ($\omega_{de} = -1$) we obtain $\gamma = 0.5547$ which is very close to the well known value 6/11. However, if $\omega_{de} = -0.9$, then $\gamma$ gives rise to 0.6405. This result is quite different from that of some other literatures. This discrepancy happens because the numerical solution includes not only the growing mode solution but also the decaying one in some literatures. Thus, the numerical estimation of $\delta$ is over estimated in some references. $\Omega_{m}^{0}$ dependence of $\gamma$ is fairly small for the viable range of the current matter energy density $0.2 \leq \Omega_{m}^{0} \leq 0.3$. (0.6% and 3% changes in $\gamma$ for $\omega_{de}$ equal to -1 and -0.9, respectively.) The difference of peculiar velocity values from the different choices of $\gamma$ is about 11% for $\Omega_{m}^{0} = 0.3$. This simple but accurate formula which covers a large class of dark energy models will provide a practical tool for galaxy redshift survey to measure the matter density and the peculiar velocity.
15011888
Effect on cosmic microwave background polarization of coupling of quintessence to pseudoscalar formed from the electromagnetic field and its dual.
We present the full set of power spectra of cosmic microwave background (CMB) temperature and polarization anisotropies due to the coupling between quintessence and pseudoscalar of electromagnetism. This coupling induces a rotation of the polarization plane of the CMB, thus resulting in a nonvanishing B mode and parity-violating TB and EB modes. Using the BOOMERANG data from the flight of 2003, we derive the most stringent constraint on the coupling strength. We find that in some cases the rotation-induced B mode can confuse the hunting for the gravitational lensing-induced B mode.
1970563
Can strong gravitational lensing constrain dark energy
We discuss the ratio of the angular diameter distances from the source to the lens, D{sub ds}, and to the observer at present, D{sub s}, for various dark energy models. It is well known that the difference of D{sub s}s between the models is apparent and this quantity is used for the analysis of Type Ia supernovae. However we investigate the difference between the ratio of the angular diameter distances for a cosmological constant, (D{sub ds}/D{sub s}){sup {lambda}}, and that for other dark energy models, (D{sub ds}/D{sub s}){sup other}, in this paper. It has been known that there is lens model degeneracy in using strong gravitational lensing. Thus, we investigate the model independent observable quantity, Einstein radius ({theta}{sub E}), which is proportional to both D{sub ds}/D{sub s} and velocity dispersion squared, {sigma}{sub v}{sup 2}. D{sub ds}/D{sub s} values depend on the parameters of each dark energy model individually. However, (D{sub ds}/D{sub s}){sup {lambda}}-(D{sub ds}/D{sub s}){sup other} for the various dark energy models, is well within the error of {sigma}{sub v} for most of the parameter spaces of the dark energy models. Thus, a single strong gravitational lensing by use of the Einstein radius may not be a proper method tomore » investigate the property of dark energy. However, better understanding to the mass profile of clusters in the future or other methods related to arc statistics rather than the distances may be used for constraints on dark energy.« less
54838721
Space charge effect on betatron oscillations
The transverse motion of the beam at the AGS was studied by analyzing the coherent beam signals, digitized at a 10 ns interval, at various beam intensities. It was found that the coherent vertical tune shift of the centroid is consistent with the space charge model due to the image charge and current induced on the vacuum chamber wall. An enhanced linear coupling at a high intensity was also observed.
119519436
A dual gravity study of the (2+1)D compact U(1) gauge theory coupled with strongly interacting matter fields
Abstract We consider the D2-brane probe action in the gravity background dual to N coincident D p -branes by treating the separation between the D2- and D p -branes as a non-dynamical parameter for p = 2 , 4 , 6 . The gauge coupling, the core size of a non-BPS instanton and the mass gap of the compact U ( 1 ) gauge theory in the D2-brane are determined as a function of the separation in the type IIA gravity region. The results are interpreted in terms of the ( 2 + 1 ) D U ( 1 ) gauge theory coupled with the matter fields which are also strongly coupled with the ( p + 1 ) D SU ( N ) gauge field. It is shown that strong coupling of the matter fields to the SU ( N ) gauge field can drastically modify their screening of the U ( 1 ) gauge field. The non-perturbative dependence of the U ( 1 ) gauge coupling on the energy scale is obtained.
116792346
Evolution of longitudinal equilibrium distribution in the adiabatic regime
Evolution of longitudinal equilibrium distribution of a hadron bunch under the beam-environment interaction is investigated based on a self-consistent solution of the Vlasov equation. The effect of this interaction on the distribution can be characterized by a dimensionless quantity in analogy to the one describing the microwave-instability criterion. In the case that the coupling impedance (Z/n) is reactive and frequency independent, the change in the distribution results in a stabilization that keeps the bunch below the instability threshold; microwave instability is thus eliminated. Monte Carlo simulation for the microwave instability agrees with analytic solution of the Vlasov equation provided that bunch shape distortion due to the coupling is taken into account.
118595903
Astrophysical implications of a visible dark matter sector from a custodially warped GUT
We explore, within the warped extra dimensional framework, the possibility of finding antimatter signals in cosmic rays (CRs) from dark matter (DM) annihilation. We find that exchange of order 100 GeV radion, an integral part of this class of models, generically results in a sizable Sommerfeld enhancement of the annihilation rate for DM mass at the TeV scale. No ad hoc dark sector is required to obtain boosted annihilation cross sections and hence signals. Such a mild hierarchy between the radion and DM masses can be natural due to the pseudo-Goldstone boson nature of the radion. We study the implications of a Sommerfeld enhancement specifically in warped grand unified theory (GUT) models, where proton stability implies a DM candidate. We show, via a partially unified Pati-Salam group, how to incorporate a custodial symmetry for Z{yields}bb into the GUT framework such that a few TeV Kaluza-Klein (KK) mass scale is allowed by electroweak precision tests. Among such models, the one with the smallest SO(10) (fully unified) representation, with SU(5) hypercharge normalization, allows us to decouple the DM from the electroweak gauge bosons. Thus, a correct DM relic density can be obtained and direct detection bounds are satisfied. Looking at robust CRmore » observables, we find a possible future signal in the p/p flux ratio consistent with current constraints. Using a different choice of representations, we show how to embed in this GUT model a similar custodial symmetry for the right-handed tau, allowing it to be strongly coupled to KK particles. Such a scenario might lead to an observed signal in CR positrons; however, the DM candidate in this case cannot constitute all of the DM in the Universe. As an aside and independent of the GUT or DM model, the strong coupling between KK particles and tau's can lead to striking LHC signals.« less
119318002
Quantization of integrable systems and a 2d/4d duality
We present a new duality between the F-terms of supersymmetric field theories defined in two-and four-dimensions respectively. The duality relates $ \mathcal{N} = 2 $ super-symmetric gauge theories in four dimensions, deformed by an Ω-background in one plane, to $ \mathcal{N} = \left( {2,2} \right) $ gauged linear σ-models in two dimensions. On the four dimensional side, our main example is $ \mathcal{N} = 2 $ SQCD with gauge group G = SU(L) and NF = 2 L fundamental flavours. Using ideas of Nekrasov and Shatashvili, we argue that the Coulomb branch of this theory provides a quantization of the classical Heisenberg SL(2) spin chain. Agreement with the standard quantization via the Algebraic Bethe Ansatz implies the existence of an isomorphism between the chiral ring of the 4 d theory and that of a certain two-dimensional theory. The latter can be understood as the worldvolume theory on a surface operator/vortex string probing the Higgs branch of the same 4 d theory. We check the proposed duality by explicit calculation at low orders in the instanton expansion. One striking consequence is that the Seiberg-Witten solution of the 4 d theory is captured by a one-loop computation in two dimensions. The duality also has interesting connections with the AGT conjecture, matrix models and topological string theory where it corresponds to a refined version of the geometric transition.