中文

Polaron测度的强耦合极限与Pekar过程

概率论 2018-06-20 v1

摘要

{\it{Polaron测度}}定义为关于有限区间[T,T][-T,T]上三维布朗增量的律P\mathbb P的变换路径测度P^ϵ,T=Zϵ,T1exp{12TTTTϵ\eϵtsω(t)ω(s)\ds\dt}\dP\widehat{\mathbb P}_{\epsilon,T}= Z_{\epsilon,T}^{-1}\,\, \exp\bigg\{\frac{1}{2}\int_{-T}^T\int_{-T}^T\frac{\epsilon\e^{-\epsilon|t-s|}}{|\omega(t)-\omega(s)|} \,\d s \,\d t\bigg\}\d\mathbb P,其中Zϵ,T Z_{\epsilon,T}为配分函数,ϵ>0\epsilon>0为常数。配分函数Zϵ,TZ_{\epsilon,T}的对数渐近行为在\cite{DV83}中已被分析,表明g0=limϵ0[limTlogZ\eps,T2T]=sup\heapψH1(R3)ψ2=1{R3R3\dx\dyψ2(x)ψ2(y)xy12ψ22}. g_0=\lim_{\epsilon \to 0}\bigg[\lim_{T\to\infty}\frac{\log Z_{\eps,T}}{2T}\bigg]=\sup_{\heap{\psi\in H^1(\R^3)}{\|\psi\|_2=1}} \bigg\{\int_{\mathbb R^3}\int_{\mathbb R^3}\d x\d y\,\frac {\psi^2(x) \psi^2(y)}{|x-y|} -\frac 12\big\|\nabla \psi\big\|_2^2\bigg\}. 在\cite{MV18}中我们分析了实际路径测度,并证明了极限P^\eps=limTP^\eps,T{\widehat {\mathbb P}}_{\eps}=\lim_{T\to\infty}\widehat{\mathbb P}_{\eps,T}存在且明确辨识了该极限,作为推论,我们还推导了在P^\eps,T\widehat{\mathbb P}_{\eps,T}(2T)1/2(ω(T)ω(T))(2T)^{-1/2}(\omega(T)-\omega(-T))的中心极限定理,并得到了极限方差σ2(\eps)\sigma^2(\eps)的表达式。在本文中,我们研究{\it{强耦合极限}}lim\eps0limTP^\eps,T=lim\eps0P^\eps\lim_{\eps\to 0} \lim_{T\to\infty} \widehat{\mathbb P}_{\eps,T}=\lim_{\eps\to 0} \widehat {\mathbb P}_\eps,并证明该极限与平稳Pekar过程的增量一致,其生成元为12Δ+(ψψ) \frac 12 \Delta+ \bigg(\frac{\nabla\psi}\psi\bigg)\cdot \nabla 对任意自由能g0g_0的极大化子ψ\psi成立。Pekar过程此前也在\cite{MV14}、\cite{KM15}和\cite{BKM15}中被辨识为{\it{平均场Polaron}}测度的极限对象。

关键词

引用

@article{arxiv.1806.06865,
  title  = {Strong coupling limit of the Polaron measure and the Pekar process},
  author = {Chiranjib Mukherjee and S. R. S. Varadhan},
  journal= {arXiv preprint arXiv:1806.06865},
  year   = {2018}
}