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
A Dvali–Gabadadze–Porrati(DGP)brane-world model with perfect fluid brane matter including a Brans-Dicke(BD)scalar field on brane was utilized to investigate the problem of the quark-hadron phase(QHP)transition in ea...A Dvali–Gabadadze–Porrati(DGP)brane-world model with perfect fluid brane matter including a Brans-Dicke(BD)scalar field on brane was utilized to investigate the problem of the quark-hadron phase(QHP)transition in early evolution of the Universe.The presence of the BD scalar field arises with several modified terms in the Friedmann equation.Because the behavior of the phase transition strongly depends on the basic evolution equations,even a small change in these relations might lead to interesting results about the time of transition.The phase transition is investigated in two scenarios,namely the first-order phase transition and smooth crossover phase transition.For the first-order scenario,which is used for the intermediate temperature regime,the evolution of the physical quantities,such as temperature and scale factor,are investigated before,during,and after the phase transition.The results show that the transition occurs in about a micro-second.In the following part,the phenomenon is studied by assuming a smooth crossover transition,where the lattice QCD data is utilized to obtain a realistic equation for the state of the matter.The investigation for this part is performed in the high and low-temperature regimes.Using the trace anomaly in the high-temperature regime specifies a simple equation of state,which states that the quark-gluon behaves like radiation.However,in the low-temperature regime,the trace anomaly is affected by discretization effects,and the hadron resonance gas model is utilized instead.Using this model,a more realistic equation of state is found in the low-temperature regime.The crossover phase transition in both regimes is considered.The results determine that the transition lasts around a few micro-seconds.Further,the transition in the low-temperature regime occurs after the transition in the high-temperature regime.展开更多
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 financially by Vice Chancellorship of Research and Technology,University of Kurdistan under research Project(98/11/2724)supported financially by Vice Chancellorship of Research and Technology,University of Kurdistan under research Project(98/10/34704)。
文摘A Dvali–Gabadadze–Porrati(DGP)brane-world model with perfect fluid brane matter including a Brans-Dicke(BD)scalar field on brane was utilized to investigate the problem of the quark-hadron phase(QHP)transition in early evolution of the Universe.The presence of the BD scalar field arises with several modified terms in the Friedmann equation.Because the behavior of the phase transition strongly depends on the basic evolution equations,even a small change in these relations might lead to interesting results about the time of transition.The phase transition is investigated in two scenarios,namely the first-order phase transition and smooth crossover phase transition.For the first-order scenario,which is used for the intermediate temperature regime,the evolution of the physical quantities,such as temperature and scale factor,are investigated before,during,and after the phase transition.The results show that the transition occurs in about a micro-second.In the following part,the phenomenon is studied by assuming a smooth crossover transition,where the lattice QCD data is utilized to obtain a realistic equation for the state of the matter.The investigation for this part is performed in the high and low-temperature regimes.Using the trace anomaly in the high-temperature regime specifies a simple equation of state,which states that the quark-gluon behaves like radiation.However,in the low-temperature regime,the trace anomaly is affected by discretization effects,and the hadron resonance gas model is utilized instead.Using this model,a more realistic equation of state is found in the low-temperature regime.The crossover phase transition in both regimes is considered.The results determine that the transition lasts around a few micro-seconds.Further,the transition in the low-temperature regime occurs after the transition in the high-temperature regime.
