ITP OpenIR
http://ir.itp.ac.cn/:80
中国科学院理论物理研究所Thu, 20 Jun 2019 05:11:56 GMT2019-06-20T05:11:56ZX (4260) revisited: A coupled channel perspective
http://ir.itp.ac.cn/:80/handle/311006/23400
Title: X (4260) revisited: A coupled channel perspective
Authors: Lu, Y; Anwar, MN; Zou, BS
Description: We calculate the probabilities of various charmed meson molecules for X (4260) under the framework of the P-3(0) model. The results indicate that, even though heavy quark spin symmetry forbids S wave coupling of D-1(D) over bar to the S-3(1) charmonia [psi(nS)], the D wave coupling is allowed and not negligible. Under this symmetry, the D-1(D) over bar can couple to D-3(1) charmonia [psi(nD)] via both S and D waves, and the overall coupling is around three times larger than that of psi(nS). The X (4260) cannot be a pure molecule but a mixture of a charmonium and various charmed meson components. Since the D-1(D) over bar couples strongly to psi(nD), our results suggest that, in the D-1(D) over bar molecular picture, the charmonium core of X (4260) is psi(nD) instead of psi(nS). As a result, the experimental fact that the R ratio has a dip around 4.26 GeV can be understood in the D-1(D) over bar molecular picture of the X (4260).Mon, 08 Apr 2019 03:38:50 GMThttp://ir.itp.ac.cn/:80/handle/311006/234002019-04-08T03:38:50ZLarge number limit of multifield inflation
http://ir.itp.ac.cn/:80/handle/311006/23401
Title: Large number limit of multifield inflation
Authors: Guo, ZK
Description: We compute the tensor and scalar spectral index n(t), n(s), the tensor-to-scalar ratio r, and the consistency relation n(t)/r in the general monomial multifield slow-roll inflation models with potentials V similar to Sigma(i)lambda(i)vertical bar phi(i)vertical bar(Pi). The general models give a novel relation that nt, ns and n(t)/r are all proportional to the logarithm of the number of fields N-f when N-f is getting extremely large with the order of magnitude around O(10(40)) thorn. An upper bound N-f less than or similar to N*e(ZN)* is given by requiring the slow variation parameter small enough where N-* is the e-folding number and Z is a function of distributions of lambda(i) and rho(i). Besides, n(t)/r differs from the single-field result - 1/8 with substantial probability except for a few very special cases. Finally, we derive theoretical boundsr r > 2/N-* (r greater than or similar to 0.03) and for nt, which can be tested by observation in the near future.Mon, 08 Apr 2019 03:38:50 GMThttp://ir.itp.ac.cn/:80/handle/311006/234012019-04-08T03:38:50ZHigher order derivative coupling to gravity and its cosmological implications
http://ir.itp.ac.cn/:80/handle/311006/23399
Title: Higher order derivative coupling to gravity and its cosmological implications
Authors: Cai, Y; Piao, YS
Description: We show that the R-(3)delta K operator in effective field theory is significant for avoiding the instability of nonsingular bounce, where R-(3) and K-mu nu are the three-dimensional Ricci scalar and the extrinsic curvature on the spacelike hypersurface, respectively. We point out that the covariant Lagrangian of R-(3)delta K, i.e., L-R(3)delta K, has the second order derivative couplings of scalar field to gravity which do not appear in Horndeski theory or its extensions but does not bring the Ostrogradski ghost. We also discuss the possible effect of L-R(3)delta K on the primordial scalar perturbation in the inflation scenario.Mon, 08 Apr 2019 03:38:49 GMThttp://ir.itp.ac.cn/:80/handle/311006/233992019-04-08T03:38:49ZLepton-flavored electroweak baryogenesis
http://ir.itp.ac.cn/:80/handle/311006/23397
Title: Lepton-flavored electroweak baryogenesis
Authors: Guo, HK; Li, YY; Liu, T; Ramsey-Musolf, M; Shu, J
Description: We explore lepton-flavored electroweak baryogenesis, driven by CP-violation in leptonic Yukawa sector, using the tau - mu system in the two Higgs doublet model as an example. This setup generically yields, together with the flavor-changing decay h -> tau mu, a tree-level Jarlskog invariant that can drive dynamical generation of baryon asymmetry during a first-order electroweak phase transition and results in CP-violating effects in the decay h -> tau tau. We find that the observed baryon asymmetry can be generated in parameter space compatible with current experimental results for the decays h -> tau mu, h -> tau tau, and tau -> mu gamma, as well as the present bound on the electric dipole moment of the electron. The baryon asymmetry generated is intrinsically correlated with the CP-violating decay h -> tau tau and the flavor-changing decay h -> tau mu, which thus may serve as "smoking guns" to test lepton-flavored electroweak baryogenesis.Mon, 08 Apr 2019 03:38:48 GMThttp://ir.itp.ac.cn/:80/handle/311006/233972019-04-08T03:38:48ZNote on the initial conditions within the effective field theory approach of cosmic acceleration
http://ir.itp.ac.cn/:80/handle/311006/23398
Title: Note on the initial conditions within the effective field theory approach of cosmic acceleration
Authors: Liu, XW; Hu, B; Zhang, Y
Description: By using the effective field theory approach, we investigate the role of initial conditions for the dark energy or modified gravity models. In detail, we consider the constant and linear parametrization of the effective Newton constant models. First, under the adiabatic assumption, the correction from the extra scalar degree of freedom in the beyond Lambda CDM model is found to be negligible. The dominant ingredient in this setup is the primordial curvature perturbation originated from the inflation mechanism, and the energy budget of the matter components is not very crucial. Second, the isocurvature perturbation sourced by the extra scalar field is studied. For the constant and linear models of the effective Newton constant, no such kind of scalar mode exists. For the quadratic model, there is a nontrivial one. However, the amplitude of the scalar field is damped away very fast on all scales. Consequently, it could not support a reasonable structure formation. Finally, we study the importance of the setup of the scalar field starting time. By setting different turn-on times, namely, a = 10(-2) and a = 10(-7), we compare the cosmic microwave background radiation temperature, lensing deflection angle autocorrelation function, and the matter power spectrum in the constant and linear models. We find there is an order of O(1%) thorn difference in the observable spectra for constant model, while for the linear model, it is smaller than O(0.1%).Mon, 08 Apr 2019 03:38:48 GMThttp://ir.itp.ac.cn/:80/handle/311006/233982019-04-08T03:38:48ZStatus and prospects of light bino-higgsino dark matter in natural SUSY
http://ir.itp.ac.cn/:80/handle/311006/23395
Title: Status and prospects of light bino-higgsino dark matter in natural SUSY
Authors: Abdughani, M; Wu, L; Yang, JM
Description: Given the recent progress in dark matter direction detection experiments, weexamine a light bino-higgsino dark matter (DM) scenario (M-1 < 100 GeV and mu < 300 GeV) in natural supersymmetry with the electroweak fine tuning measure Delta(EW) < 30. By imposing various constraints, we note that: (i) For sign(mu/M-1) = +1, the parameter space allowed by the DM relic density and collider bounds can almost be excluded by the very recent spin-independent (SI) scattering cross-section limits from the XENON1T (2017) experiment. (ii) For sign(mu/M-1) = -1, the SI limits can be evaded due to the cancelation effects in the h<(chi)over bar>(0)(1)(chi) over bar (0)(1) coupling, while rather stringent constraints come from the PandaX-II (2016) spin-dependent (SD) scattering cross-section limits, which can exclude the higgsino mass vertical bar mu vertical bar and the LSP mass m (chi) over bar (0)(1) up to about 230 and 37 GeV, respectively. Furthermore, the surviving parameter space will be fully covered by the projected XENON1T experiment or the future trilepton searches at the HL-LHC.Mon, 08 Apr 2019 03:38:47 GMThttp://ir.itp.ac.cn/:80/handle/311006/233952019-04-08T03:38:47ZLearning from Higgs physics at future Higgs factories
http://ir.itp.ac.cn/:80/handle/311006/23396
Title: Learning from Higgs physics at future Higgs factories
Authors: Gu, JY; Li, HL; Liu, Z; Su, SF; Su, W
Description: Future Higgs factories can reach impressive precision on Higgs property measurements. In this paper, instead of conventional focus of Higgs precision in certain interaction bases, we explore its sensitivity to new physics models at the electron-positron colliders. In particular, we study two categories of new physics models, Standard Model (SM) with a real scalar singlet extension, and Two Higgs Double Model (2HDM) as examples of weakly-interacting models, Minimal Composite Higgs Model (MCHM) and three typical patterns of the more general operator counting for strong interacting models as examples of strong dynamics. We perform a global fit to various Higgs search channels to obtain the 95% C.L. constraints on the model parameter space. In the SM with a singlet extension, we obtain the limits on the singlet-doublet mixing angle sin theta, as well as the more general Wilson coefficients of the induced higher dimensional operators. In the 2HDM, we analyze tree level effects in tan beta vs. cos(beta-alpha) plane, as well as the one-loop contributions from the heavy Higgs bosons in the alignment limit to obtain the constraints on heavy Higgs masses for different types of 2HDM. In strong dynamics models, we obtain lower limits on the strong dynamics scale. In addition, once deviations of Higgs couplings are observed, they can be used to distinguish different models. We also compare the sensitivity of various future Higgs factories, namely Circular Electron Positron Collider (CEPC), Future Circular Collider (FCC)-ee and International Linear Collider (ILC).Mon, 08 Apr 2019 03:38:47 GMThttp://ir.itp.ac.cn/:80/handle/311006/233962019-04-08T03:38:47ZZ(c)(3900): What has been really seen?
http://ir.itp.ac.cn/:80/handle/311006/23394
Title: Z(c)(3900): What has been really seen?
Authors: Albaladejo, M; Guo, FK; Hidalgo-Duque, C; Nieves, J
Description: The Z(c)(+/-)(3900)/Z(c)(+/-)(3885) resonant structure has been experimentally observed in the Y(4260) -> J/Psi pi pi and Y(4260) -> (D) over bar* D pi decays. This structure is intriguing since it is a prominent candidate of an exotic hadron. Yet, its nature is unclear so far. In this work, we simultaneously describe the (D) over bar* D and J/Psi pi invariant mass distributions in which the Z(c) peak is seen using amplitudes with exact unitarity. Two different scenarios are statistically acceptable, where the origin of the Z(c) state is different. They correspond to using energy dependent or independent (D) over bar *D S-wave interaction. In the first one, the Z(c) peak is due to a resonance with a mass around the D (D) over bar* threshold. In the second one, the Z(c) peak is produced by a virtual state which must have a hadronic molecular nature. In both cases the two observations, Z(c)(+/-)(3900) and Z(c)(+/-)(3885), are shown to have the same common origin, and a (D) over bar *D bound state solution is not allowed. Precise measurements of the line shapes around the D (D) over bar* threshold are called for in order to understand the nature of this state. (C) 2016 The Authors. Published by Elsevier B.V.Mon, 08 Apr 2019 03:18:24 GMThttp://ir.itp.ac.cn/:80/handle/311006/233942019-04-08T03:18:24ZWeyl magnons in breathing pyrochlore antiferromagnets
http://ir.itp.ac.cn/:80/handle/311006/23392
Title: Weyl magnons in breathing pyrochlore antiferromagnets
Authors: Li, FY; Li, YD; Kim, YB; Balents, L; Yu, Y; Chen, G
Description: Frustrated quantum magnets not only provide exotic ground states and unusual magnetic structures, but also support unconventional excitations in many cases. Using a physically relevant spin model for a breathing pyrochlore lattice, we discuss the presence of topological linear band crossings of magnons in antiferromagnets. These are the analogues of Weyl fermions in electronic systems, which we dub Weyl magnons. The bulk Weyl magnon implies the presence of chiral magnon surface states forming arcs at finite energy. We argue that such antiferromagnets present a unique example, in which Weyl points can be manipulated in situ in the laboratory by applied fields. We discuss their appearance specifically in the breathing pyrochlore lattice, and give some general discussion of conditions to find Weyl magnons, and how they may be probed experimentally. Our work may inspire a re-examination of the magnetic excitations in many magnetically ordered systems.Mon, 08 Apr 2019 03:18:23 GMThttp://ir.itp.ac.cn/:80/handle/311006/233922019-04-08T03:18:23ZWormholes supported by phantom energy from Shan-Chen cosmological fluids
http://ir.itp.ac.cn/:80/handle/311006/23393
Title: Wormholes supported by phantom energy from Shan-Chen cosmological fluids
Authors: Wang, D; Meng, XH
Description: In the present paper, the exact solutions of spherically symmetrical Einstein field equations describing wormholes supported by phantom energy that violates the null energy condition from Shan-Chen background fluid are obtained. We have considered the important case of the model parameter psi approximate to 1, which corresponds to the "saturation effect", and this regime corresponds to an effective form of "asymptotic freedom" for the fluids, but occurring at cosmological rather than subnuclear scales. Then we investigate the allowed range for the values of the model parameters g and omega when the spacetime metrics describe wormholes and discuss the possible singularities of the solutions, finding that the obtained spacetimes are geodesically complete. Furthermore, we construct two traversable wormholes through matching our obtained interior solutions to the exterior Schwarzschild solutions and analyze the traversablities of thewormholes. Finally, we consider the case of anisotropic pressure and discover that the transverse pressure also crosses the phantom divide -1 with the growth of the wormhole dimension, and it tends to be the same as the radial pressure with the growth of the wormhole radius.Mon, 08 Apr 2019 03:18:23 GMThttp://ir.itp.ac.cn/:80/handle/311006/233932019-04-08T03:18:23Z