Pis’ma v ZhETF, vol. 105, iss. 4, pp. 229 – 229 2017 February 25 c Fluctuational shift of nematic-isotropic phase transition temperature E. I.Kats1) Landau Institute for Theoretical Physics, RAS, 142432 Chernogolovka, Russia Submitted 19 December 2016 DOI: 10.7868/S0370274X17040087 In this work we discuss a macroscopic counterpart to the microscopic mechanism of the straightening dimer mesogens conformations, proposed recently by S.M. Saliti, M.G.Tamba, S.N. Sprunt, C.Welch, G.H.Mehl, A. Jakli, J.T.Gleeson (Phys. <...> Rev. Lett. 116, 217801 (2016)) to explain their experimental observation of the unprecedentedly large shift of the nematic – isotropic transition temperature. <...> Our interpretation is based on singular longitudinal fluctuations of the nematic order parameter. <...> Since these fluctuations are governed by the Goldstone director fluctuations they exist only in the nematic state. <...> External magnetic field suppresses the singular longitudinal fluctuations of the order parameter (similarly as it is the case for the transverse director fluctuations, although with a different scaling over the magnetic field). <...> The reduction of the fluctuations changes the equilibrium value of the modulus of the order parameter in the nematic state. <...> Therefore it leads to additional (with respect to the mean field contribution) fluctuational shift of the nematic – isotropic transition temperature: ∆Tc(H) ∝ H3/2. <...> This is our main result in the work, which is ready to be confronted with experimental data. <...> Ourmechanismworks for any nematic liquid crystals, however the magnitude of the fluctuational shift increases with decrease of the Frank elastic moduli. <...> Since some of these moduli supposed to be anomalously small for so-called bent-core or dimer nematic liquid crystals, just these liquid crystals are promising candidates for the observation of the predicted fluctuational shift of the phase transition temperature. <...> This work was funded by the Russian Science Foundation (grant #14-12-00475). <...> Full text of the paper is published in JETP Letters journal. <...> In this work we discuss a macroscopic counterpart to the microscopic mechanism of the straightening dimer mesogens conformations, proposed recently by S.M. Saliti, M.G. Tamba, S.N. Sprunt, C. Welch, G.H. Mehl, A. Jakli, J.T. Gleeson (Phys. <...> Rev. Lett. 116, 217801 (2016)) to explain their <...>