A key role that naturalness plays in particle physics is the narrowing of focus and the status elevation of speculative theories. There are several ways a speculative theory's status can be elevated, including the assessment that it is more likely than other speculative theories. It is argued that naturalness claims on speculative theories are just those -- claims that natural theories are...
I consider four reasons to adopt the criterion of naturalness in the context of effective field theories (EFTs) of fundamental phenomena, the first three less compelling than the fourth. The first three are (i) naturalness has had modest empirical success, (ii) it can be quantified, and (iii) it is consistent with an image of EFTs that is underwritten by what Williams (2015) calls a "central...
My aim will be to distinguish two notions of naturalness in use in BSM physics. One way of understanding naturalness is as a prohibition on sensitive dependencies of a theory's description of low-energy physics on details of the theory's description of high-energy physics. I will argue that considerations from the general structure of effective field theory provide motivation for this notion...
I argue that the SM in the Higgs phase does not suffer form a
hierarchy problem'' and that similarly thecosmological constant
problem'' resolves itself if we understand the SM as a low energy
effective theory emerging from a cut-off medium at the Planck scale.
We discuss these issues under the condition of a stable Higgs vacuum,
which allows to extend the SM up to the Planck length. The...
Naturalness arguments have been extremely influential
in the foundations of physics during the last decades.
I explain why they are based on faulty reasoning.
It is an old idea that we may live in a multiverse. The fundamental parameters we observe in our local universe are then, at least to some extent, accidental. More recently, technical progress in superstring theory, which is arguably the leading candidate for a theory of quantum gravity, has given strong support to this idea. Concretely, the crucial progress came with the discovery of a very...
Finetuning describes unlikely coincidences on an effective level of description which are expected to be explained in a more fundamental theory. In this talk a fresh view on the topic of Naturalness and Finetuning is presented which is based on a “holistic" concept for the most fundamental layer of reality. We start with recent research on the abundances of leptons, baryons and dark matter in...
Asymptotic Safety provides a possible mechanism for a consistent and
predictive high-energy completion of gravity and gravity-matter theories.
The key ingredient in the construction is an interacting renormalization
group fixed point which controls physics at trans-Planckian scales.
Relevant couplings have the task of identifying a given asymptotically
safe theory within the unstable manifold...
No evidence of "new physics" in general and supersymmetry in
particular was found so far by LHC experiments, and this
situation has led some voices in the physics community to call
for the abandonment of the "naturalness" criterion, while other
scientists have felt the need to break a lance in its defense by
claiming that, at least in some sense, it has already led to
successes and therefore...
The hierarchy problem in the Standard Model is usually understood as both a technical problem of stability of the calculation of the quantum corrections to the masses of the Higgs sector and of the unnatural difference between the Planck and gauge breaking scales. Leaving aside the gauge sector, we implement on a purely scalar toy model a mechanism for generating naturally light scalar...
The paper discusses the way in which the perspective of a universal fundamental theory without free parameters changes the role of finetuning arguments in physics. It has been suggested that finetuning arguments merely express aesthetic preferences. The assumption of a fundamental theory without free parameters allows for a substantially stronger role of finetuning arguments that is more...
Undeniably, the naturalness principle, acting as a guiding principle, has had a major role in particle physics during the last decades, in particular in model building. Nowadays, one can find a wide range of different definitions, some of them seem mutually exclusive, but traditionally its notion has been linked to the fine-tuning problem. Its operational definition can be stated as the...
Over the past century, a fruitful strategy for constructing new models in both particle physics and condensed matter physics has been to develop analogies between theories for the two domains. Two of the theoretical components at the heart of naturalness arguments in particle physics were inspired by analogies with condensed matter physics: renormalization group (RG) methods (which are...
