Graduate School of Science and Technology, Niigata University, Niigata 950-2181, Japan.
Phys Rev Lett. 2013 Apr 26;110(17):172001. doi: 10.1103/PhysRevLett.110.172001. Epub 2013 Apr 22.
Towards the feasibility study of the electroweak baryogenesis in realistic technicolor scenario, we investigate the phase structure of (2+N(f))-flavor QCD, where the mass of two flavors is fixed to a small value and the others are heavy. For the baryogenesis, an appearance of a first-order phase transition at finite temperature is a necessary condition. Using a set of configurations of two-flavor lattice QCD and applying the reweighting method, the effective potential defined by the probability distribution function of the plaquette is calculated in the presence of additional many heavy flavors. Through the shape of the effective potential, we determine the critical mass of heavy flavors separating the first-order and crossover regions and find it to become larger with N(f). We moreover study the critical line at finite density and the first-order region is found to become wider as increasing the chemical potential. Possible applications to real (2+1)-flavor QCD are discussed.
为了研究现实色荷情景下的电弱重子生成的可行性，我们研究了（2+N(f)）-味道 QCD 的相结构，其中两种味道的质量被固定在一个小值，而其他味道的质量则很重。对于重子生成，有限温度下的一级相变的出现是一个必要条件。我们使用一组两味道格点 QCD 的组态，并应用重加权方法，在存在额外的许多重味道的情况下，计算由 plaquette 的概率分布函数定义的有效势。通过有效势的形状，我们确定了区分一级和交越区域的重味道的临界质量，并发现它随着 N(f) 的增加而变大。我们还研究了有限密度下的临界线，发现随着化学势的增加，一级区域变得更宽。讨论了对真实（2+1）-味道 QCD 的可能应用。
