اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدA Renormalization Group Approach to the Cosmological Constant Problem
116
0
0.0
(
0
)
تأليف
S.-H. Henry Tye
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
In an earlier paper, it is proposed that, due to resonance tunneling effect, tunneling from a large cosmological constant $Lambda$ site in the stringy comic landscape can be fast, while tunneling from a small $Lambda$ site may take exponentially long time. Borrowing the renormalization group analysis of the conductance in the Anderson localization transition, we treat the landscape as a multi-dimensional random potential and find that the vastness of the landscape leads to a sharp transition at a small critical value $Lambda_{c}$ from fast tunneling for $Lambda > Lambda_{c} $ to suppressed tunneling for $Lambda_{c} > Lambda >0$. Mobility in the landscape makes eternal inflation highly unlikely. As an illustration, we find that $Lambda_{c}$ can easily be exponentially small compared to the string/Planck scale. These properties may help us in finding a qualitative understanding why todays dark energy is so small.
قيم البحث
اقرأ أيضاً
Renormalization group (RG) applications to cosmological problems often encounter difficulties in the interpretation of the field independent term in the effective potential. While this term is constant with respect to field variations, it generally d
epends on the RG scale k. Since the RG running could be associated with the temporal evolution of the Universe according to the identification $k sim 1/t$, one can treat the field independent constant, i.e., the $Lambda$ term in Einsteins equations as a running (scale-dependent) parameter. Its scale dependence can be described by nonperturbative RG, but it has a serious drawback, namely $k^4$ and $k^2$ terms appear in the RG flow in its high-energy (UV) limit which results in a rampant divergent behaviour. Here, we propose a subtraction method to handle this unphysical UV scaling and provides us a framework to build up a reliable solution to the cosmological constant problem.
We consider a model with two parallel (positive tension) 3-branes separated by a distance $L$ in 5-dimensional spacetime. If the interbrane space is anti-deSitter, or is not precisely anti-deSitter but contains no event horizons, the effective 4-dime
nsional cosmological constant seen by observers on one of the branes (chosen to be the visible brane) becomes exponentially small as $L$ grows large.
In order to understand the dynamical mechanism of the friction phenomena, we heavily rely on the numerical analysis using various methods: molecular dynamics, Langevin equation, lattice Boltzmann method, Monte Carlo, e.t.c.. We propose a new method w
hich has the following characteristic points: 1) the geometrical approach to the statistical mechanical system; 2) the continuum approach using Feynmans path integral (generalized version); 3) the holographic (higher-dimensional) approach; 4) the renormalization phenomenon takes place in order to treat the statistical fluctuation.
Based on quantum mechanical framework for the minimal length uncertainty, we demonstrate that the generalized uncertainty principle (GUP) parameter could be best constrained by recent gravitational waves observations on one hand. On other hand this s
uggests modified dispersion relations (MDRs) enabling an estimation for the difference between the group velocity of gravitons and that of photons. Utilizing features of the UV/IR correspondence and the obvious similarities between GUP (including non-gravitating and gravitating impacts on Heisenberg uncertainty principle) and the discrepancy between the theoretical and the observed cosmological constant (apparently manifesting gravitational influences on the vacuum energy density), we suggest a possible solution for the cosmological constant problem.
We introduce a novel method to circumvent Weinbergs no-go theorem for self-tuning the cosmological vacuum energy: a Lorentz-violating finite-temperature superfluid can counter the effects of an arbitrarily large cosmological constant. Fluctuations of
the superfluid result in the graviton acquiring a Lorentz-violating mass and we identify a unique class of theories that are pathology free, phenomenologically viable, and do not suffer from instantaneous modes. This new and hitherto unidentified phase of massive gravity propagates the same degrees of freedom as general relativity with an additional Lorentz-violating scalar that is introduced by higher-derivative operators in a UV insensitive manner. The superfluid is therefore a consistent infrared modification of gravity. We demonstrate how the superfluid can degravitate a cosmological constant and discuss its phenomenology.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
