Recently proposed two swampland criteria that arising from string theory landscape leads to the important challenge of the realization of single-field inflationary models. Especially one of swampland criteria which im...Recently proposed two swampland criteria that arising from string theory landscape leads to the important challenge of the realization of single-field inflationary models. Especially one of swampland criteria which implies a large tensor-to-scalar ratio is strongly in tension with recent observational results. In this paper, we explore the possibility the swampland conjectures could be compatible with single-field inflationary scenarios if the effects due to the quantum theory of gravity are considered. We show that the quantum gravitational effects due to the nonlinear dispersion relation provides significant modifications on the amplitude of both the scalar and tensor perturbation spectra. Such modifications could be either raise or reduce the perturbation spectra depending on the values of the parameters in the nonlinear terms of the dispersion relations. Therefore, these effects can reduce the tensor-to-scalar ratio to a smaller value, which helps to relax the tension between the swampland conjecture and observational data.展开更多
In this paper,we study a theory of gravity called mimetic f(R,T)in the presence of swampland dS conjecture.For this purpose,we introduce several inflation solutions of the Hubble parameter H(N)from f(R,T)=R+δT gravit...In this paper,we study a theory of gravity called mimetic f(R,T)in the presence of swampland dS conjecture.For this purpose,we introduce several inflation solutions of the Hubble parameter H(N)from f(R,T)=R+δT gravity model,in which R is Ricci scalar,and T denotes the trace of the energy–momentum tensor.Also,δand N are the free parameter and a number of e-fold,respectively.Then we calculate quantities such as potential,Lagrange multiplier,slow-roll,and some cosmological parameters such as nsand r.Then we challenge the mentioned inflationary model from the swampland dS conjecture.We discuss the stability of the model and investigate the compatibility or incompatibility of this inflationary scenario with the latest Planck observable data.展开更多
In this paper,using Hamiltonian formalism,we obtain solutions for constant-roll inflation according to the noncommutativity and the non-minimal coupling field of the Lagrangian.We consider three different types of cou...In this paper,using Hamiltonian formalism,we obtain solutions for constant-roll inflation according to the noncommutativity and the non-minimal coupling field of the Lagrangian.We consider three different types of couplings:power-law,exponential,and logarithmic.Subsequently,by plotting some figures,we study the effects of these coupling in constant-roll inflation with noncommutative parameters.We identify and specify the permissible regions of each case of the swampland conjecture and determine the best model.We find that the exponential,logarithmic,and power-law couplings with agree with the dS swampland conjecture.These couplings provide similar results in both cases,some of which are compatible and some incompatible with the dS swampland conjectures.Moreover,is more compatible than,and the consistency value in the second boundary condition is much higher than in the first.The order of better compatibility of couplings with the swampland conjecture is ranked as follows:exponential non-minimal coupling,logarithmic non-minimal coupling,and power-law non-minimal coupling.For each type of coupling,we calculate the values of the scalar spectral index and the tensor-to-scalar ratio r for two different potentials and compare them with the observational data from Planck 2018.We also determine the range of the free parameters of the further refining de Sitter swampland conjecture(FRDSSC)that make the model consistent with the conjecture.We find that the model satisfies the FRDSSC for all types of couplings and both potentials,with some constraints on the parameters.展开更多
In this study,we revisit supersymmetric(SUSY)hybrid inflation within the context of considering the latest Cosmic Microwave Background(CMB)observations and swampland conjectures.We demonstrate that SUSY hybrid inflati...In this study,we revisit supersymmetric(SUSY)hybrid inflation within the context of considering the latest Cosmic Microwave Background(CMB)observations and swampland conjectures.We demonstrate that SUSY hybrid inflation remains consistent with Planck 2018 data when radiative,soft mass,and supergravity(SUGRA)corrections are applied to the scalar potential.It is commonly perceived that SUSY hybrid inflation with a minimal Kahler potential results in a gauge symmetry breaking scale M of O(10^(15))GeV,leading to issues with the proton decay rate.In our analysis,we introduce a novel parameter space that alleviates the proton decay issue by achieving M~10^(16) GeV with M_(S)^(2)<0 and am_(3/2)>0.This scenario necessitates a soft SUSY breaking scale|M_(S)|■10^(6) GeV.Further,we find that the tensor-to-scalar ratio r spans from 10^(-16) to 10^(-6),indicating a very small value.This small ratio allows the modified swampland criteria to hold,although satisfying the trans-Planckian censorship conjecture(TCC)remains challenging.To address this,we also explo non-minimal Kahler potentials.By fixing the spectral index at n_(S)=0.9665,consistent with the central value of Planck 2018 data,and setting M=2×10^(16)GeV,we present our calculations.We show that the canonical measure of primordial gravitational waves,r,for M_(S)=1 TeV,m_(3/2)=1 TeV,and k_(S)<0 for N=1 and N=2,ranges from 10^(-5) to 0.01,rendering it detectable by Planck and upcoming experiments such as LiteBIRD,Simons Observatory,PRISM,PIXIE,CORE,CMB-S4,and CMB-HD.Additionally,we outline the parametric space and provide benchmark points for the non-minimal case to ensure compatibility with both the modified swampland conjecture and TCC.展开更多
The effective vacuum energy density contributed by the non-trivial contortion distribution and the bare vacuumenergy density can be viewed as the energy density of the auxiliary quintessence field potential.We find th...The effective vacuum energy density contributed by the non-trivial contortion distribution and the bare vacuumenergy density can be viewed as the energy density of the auxiliary quintessence field potential.We find thatthe negative bare vacuum energy density from string landscape leads to a monotonically decreasing quintessence potentialwhile the positive one from swampland leads to the metastable or stable de Sitter-like potential.Moreover,thenon-trivial Brans-Dicke like coupling between the quintessence field and gravitation field is necessary in the lattercase.展开更多
We have recently pointed out [1] that the string swampland conjectures [2], if true, provide important constraints on dark energy models. The constraints apply to the field range of a scalar field Φ described by an e...We have recently pointed out [1] that the string swampland conjectures [2], if true, provide important constraints on dark energy models. The constraints apply to the field range of a scalar field Φ described by an effective field theory, and to the slope of the potential Ⅴ of such fields.展开更多
In this paper,we analyze inflationary parameters and swampland conjectures in the presence of a scalar field and Chaplygin models.We examine inflationary parameters,such as slow-roll parameters,scalar and tensor power...In this paper,we analyze inflationary parameters and swampland conjectures in the presence of a scalar field and Chaplygin models.We examine inflationary parameters,such as slow-roll parameters,scalar and tensor power spectra,spectral index,and tensor-to-scalar ratio,in the presence of a scalar field and Chaplygin gas models.We also discuss recently proposed swampland conjectures.We assume that the inflationary expansion is driven by a standard scalar field with a decay ratioΓthat has a generic power-law dependence on the scalar field 0 and that the temperature of the thermal bath T is given byΓ(φ,T)=C_(φ)T^(a)/φ^(a-1),where C_(φ)is a dimensionless parameter and a is the inflation decay rate.In a scenario where our model operates within a robust dissipative environment(R>>1),we analyze both fundamental and perturbative dynamics to extract key inflationary parameters.These include the scalar power spectrum P_(R),dissipative ratio R,scalar spectral index n_(s),tensor-to-scalar ratio r,running of the scalar spectral index dn_s/dlnk,and generalized ratio of the swampland de-Sitter conjecture T'V/V'T for three different potentials.展开更多
In this study,the scenario of a two-component warm tachyon inflation is considered,where the tachyon field plays the role of the inflaton by driving the inflation.During inflation,the tachyon scalar field interacts wi...In this study,the scenario of a two-component warm tachyon inflation is considered,where the tachyon field plays the role of the inflaton by driving the inflation.During inflation,the tachyon scalar field interacts with the other component of the Universe,which is assumed to be photon gas,i.e.,radiation.The interacting term contains a dissipation coefficient,and the study is modeled based on two different and familiar choices of the coefficient that were studied in the literature.By employing the latest observational data,the acceptable ranges for the free parameters of the model are obtained.For any choice within the estimated ranges,there is an acceptable concordance between the theoretical predictions and observations.Although the model is established based on several assumptions,it is crucial to verify their validity for the obtained values of the free parameters of the model.It is found that the model is not self-consistent for all values of the ranges,and for some cases,the assumptions are violated.Therefore,to achieve both self-consistency and agreement with the data,the parameters of the model must be constrained.Subsequently,we consider the recently proposed swampland conjecture,which imposes two conditions on the inflationary models.These criteria rule out some inflationary models;however,warm inflation is among those that successfully satisfy the swampland criteria.We conduct a precise investigation,which indicates that the proposed warm tachyon inflation cannot satisfy the swampland criteria for some cases.In fact,for the first case of the dissipation coefficient,in which,there is dependency only on the scalar field,the model agrees with observational data.However,it is in direct tension with the swampland criteria.Nevertheless,for the second case,wherein the dissipation coefficient has a dependency on both the scalar field and temperature,the model exhibits acceptable agreement with observational data,and suitably satisfies the swampland criteria.展开更多
We propose a refined version of trans-Planckian censorship conjecture(TCC), which could be elaborated from the strong scalar weak gravity conjecture combined with some entropy bounds. In particular, no fine-tuning on ...We propose a refined version of trans-Planckian censorship conjecture(TCC), which could be elaborated from the strong scalar weak gravity conjecture combined with some entropy bounds. In particular, no fine-tuning on the inflation model-building is required in the refined TCC, and it automatically passes the tests from those stringy examples that support the original TCC.Furthermore, our refined TCC could be consistent with hilltop eternal inflation.展开更多
基金Supported by National Natural Science Foundation of China under Grant No.11675143the Fundamental Research for the Provincial Universities of Zhejiang in China under Grant No.RF-A2019015
文摘Recently proposed two swampland criteria that arising from string theory landscape leads to the important challenge of the realization of single-field inflationary models. Especially one of swampland criteria which implies a large tensor-to-scalar ratio is strongly in tension with recent observational results. In this paper, we explore the possibility the swampland conjectures could be compatible with single-field inflationary scenarios if the effects due to the quantum theory of gravity are considered. We show that the quantum gravitational effects due to the nonlinear dispersion relation provides significant modifications on the amplitude of both the scalar and tensor perturbation spectra. Such modifications could be either raise or reduce the perturbation spectra depending on the values of the parameters in the nonlinear terms of the dispersion relations. Therefore, these effects can reduce the tensor-to-scalar ratio to a smaller value, which helps to relax the tension between the swampland conjecture and observational data.
文摘In this paper,we study a theory of gravity called mimetic f(R,T)in the presence of swampland dS conjecture.For this purpose,we introduce several inflation solutions of the Hubble parameter H(N)from f(R,T)=R+δT gravity model,in which R is Ricci scalar,and T denotes the trace of the energy–momentum tensor.Also,δand N are the free parameter and a number of e-fold,respectively.Then we calculate quantities such as potential,Lagrange multiplier,slow-roll,and some cosmological parameters such as nsand r.Then we challenge the mentioned inflationary model from the swampland dS conjecture.We discuss the stability of the model and investigate the compatibility or incompatibility of this inflationary scenario with the latest Planck observable data.
文摘In this paper,using Hamiltonian formalism,we obtain solutions for constant-roll inflation according to the noncommutativity and the non-minimal coupling field of the Lagrangian.We consider three different types of couplings:power-law,exponential,and logarithmic.Subsequently,by plotting some figures,we study the effects of these coupling in constant-roll inflation with noncommutative parameters.We identify and specify the permissible regions of each case of the swampland conjecture and determine the best model.We find that the exponential,logarithmic,and power-law couplings with agree with the dS swampland conjecture.These couplings provide similar results in both cases,some of which are compatible and some incompatible with the dS swampland conjectures.Moreover,is more compatible than,and the consistency value in the second boundary condition is much higher than in the first.The order of better compatibility of couplings with the swampland conjecture is ranked as follows:exponential non-minimal coupling,logarithmic non-minimal coupling,and power-law non-minimal coupling.For each type of coupling,we calculate the values of the scalar spectral index and the tensor-to-scalar ratio r for two different potentials and compare them with the observational data from Planck 2018.We also determine the range of the free parameters of the further refining de Sitter swampland conjecture(FRDSSC)that make the model consistent with the conjecture.We find that the model satisfies the FRDSSC for all types of couplings and both potentials,with some constraints on the parameters.
文摘In this study,we revisit supersymmetric(SUSY)hybrid inflation within the context of considering the latest Cosmic Microwave Background(CMB)observations and swampland conjectures.We demonstrate that SUSY hybrid inflation remains consistent with Planck 2018 data when radiative,soft mass,and supergravity(SUGRA)corrections are applied to the scalar potential.It is commonly perceived that SUSY hybrid inflation with a minimal Kahler potential results in a gauge symmetry breaking scale M of O(10^(15))GeV,leading to issues with the proton decay rate.In our analysis,we introduce a novel parameter space that alleviates the proton decay issue by achieving M~10^(16) GeV with M_(S)^(2)<0 and am_(3/2)>0.This scenario necessitates a soft SUSY breaking scale|M_(S)|■10^(6) GeV.Further,we find that the tensor-to-scalar ratio r spans from 10^(-16) to 10^(-6),indicating a very small value.This small ratio allows the modified swampland criteria to hold,although satisfying the trans-Planckian censorship conjecture(TCC)remains challenging.To address this,we also explo non-minimal Kahler potentials.By fixing the spectral index at n_(S)=0.9665,consistent with the central value of Planck 2018 data,and setting M=2×10^(16)GeV,we present our calculations.We show that the canonical measure of primordial gravitational waves,r,for M_(S)=1 TeV,m_(3/2)=1 TeV,and k_(S)<0 for N=1 and N=2,ranges from 10^(-5) to 0.01,rendering it detectable by Planck and upcoming experiments such as LiteBIRD,Simons Observatory,PRISM,PIXIE,CORE,CMB-S4,and CMB-HD.Additionally,we outline the parametric space and provide benchmark points for the non-minimal case to ensure compatibility with both the modified swampland conjecture and TCC.
基金Supported by the National Natural Science Foundation of China(11775080,11865016)。
文摘The effective vacuum energy density contributed by the non-trivial contortion distribution and the bare vacuumenergy density can be viewed as the energy density of the auxiliary quintessence field potential.We find thatthe negative bare vacuum energy density from string landscape leads to a monotonically decreasing quintessence potentialwhile the positive one from swampland leads to the metastable or stable de Sitter-like potential.Moreover,thenon-trivial Brans-Dicke like coupling between the quintessence field and gravitation field is necessary in the lattercase.
基金supported by the Funding from the European Research Council(ERC)under the European Unions Horizon 2020 Research and Innovation Program(Grant No.801781)the Swiss National Science Foundation(Grant No.1797400)+1 种基金an NSERC Discovery Grantthe Canada Research Chair Program
文摘We have recently pointed out [1] that the string swampland conjectures [2], if true, provide important constraints on dark energy models. The constraints apply to the field range of a scalar field Φ described by an effective field theory, and to the slope of the potential Ⅴ of such fields.
文摘In this paper,we analyze inflationary parameters and swampland conjectures in the presence of a scalar field and Chaplygin models.We examine inflationary parameters,such as slow-roll parameters,scalar and tensor power spectra,spectral index,and tensor-to-scalar ratio,in the presence of a scalar field and Chaplygin gas models.We also discuss recently proposed swampland conjectures.We assume that the inflationary expansion is driven by a standard scalar field with a decay ratioΓthat has a generic power-law dependence on the scalar field 0 and that the temperature of the thermal bath T is given byΓ(φ,T)=C_(φ)T^(a)/φ^(a-1),where C_(φ)is a dimensionless parameter and a is the inflation decay rate.In a scenario where our model operates within a robust dissipative environment(R>>1),we analyze both fundamental and perturbative dynamics to extract key inflationary parameters.These include the scalar power spectrum P_(R),dissipative ratio R,scalar spectral index n_(s),tensor-to-scalar ratio r,running of the scalar spectral index dn_s/dlnk,and generalized ratio of the swampland de-Sitter conjecture T'V/V'T for three different potentials.
基金The work of A.M.has been supported financially by‘Vice Chancellorship of Research and Technology,University of Kurdistan’under research Project No.98/10/34704The work of T.G.has been supported financially by‘Vice Chancellorship of Research and Technology,University of Kurdistan’under research Project No.98/11/2724。
文摘In this study,the scenario of a two-component warm tachyon inflation is considered,where the tachyon field plays the role of the inflaton by driving the inflation.During inflation,the tachyon scalar field interacts with the other component of the Universe,which is assumed to be photon gas,i.e.,radiation.The interacting term contains a dissipation coefficient,and the study is modeled based on two different and familiar choices of the coefficient that were studied in the literature.By employing the latest observational data,the acceptable ranges for the free parameters of the model are obtained.For any choice within the estimated ranges,there is an acceptable concordance between the theoretical predictions and observations.Although the model is established based on several assumptions,it is crucial to verify their validity for the obtained values of the free parameters of the model.It is found that the model is not self-consistent for all values of the ranges,and for some cases,the assumptions are violated.Therefore,to achieve both self-consistency and agreement with the data,the parameters of the model must be constrained.Subsequently,we consider the recently proposed swampland conjecture,which imposes two conditions on the inflationary models.These criteria rule out some inflationary models;however,warm inflation is among those that successfully satisfy the swampland criteria.We conduct a precise investigation,which indicates that the proposed warm tachyon inflation cannot satisfy the swampland criteria for some cases.In fact,for the first case of the dissipation coefficient,in which,there is dependency only on the scalar field,the model agrees with observational data.However,it is in direct tension with the swampland criteria.Nevertheless,for the second case,wherein the dissipation coefficient has a dependency on both the scalar field and temperature,the model exhibits acceptable agreement with observational data,and suitably satisfies the swampland criteria.
基金supported by the National Natural Science Foundation of China(Grant Nos.11435006,11647601,11690022,11821505,and 11851302)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB23030100)+1 种基金the Key Research Program of Frontier Sciences of Chinese Academy of Sciencessupported by the postdoctoral scholarship of Tufts University from National Science Foundation。
文摘We propose a refined version of trans-Planckian censorship conjecture(TCC), which could be elaborated from the strong scalar weak gravity conjecture combined with some entropy bounds. In particular, no fine-tuning on the inflation model-building is required in the refined TCC, and it automatically passes the tests from those stringy examples that support the original TCC.Furthermore, our refined TCC could be consistent with hilltop eternal inflation.
