Search results for "hierarchy problem"
showing 10 items of 12 documents
Relaxion Stars and their detection via Atomic Physics
2019
The cosmological relaxion can address the hierarchy problem, while its coherent oscillations can constitute dark matter in the present universe. We consider the possibility that the relaxion forms gravitationally bound objects that we denote as relaxion stars. The density of these stars would be higher than that of the local dark matter density, resulting in enhanced signals in table-top detectors, among others. Furthermore, we raise the possibility that these objects may be trapped by an external gravitational potential, such as that of the Earth or the Sun. This leads to formation of relaxion halos of even greater density. We discuss several interesting implications of relaxion halos, as …
The Hunt for New Physics at the Large Hadron Collider
2010
233 páginas.-- AHEP Group: et al..-- El Pdf del artículo es la versión pre-print: arXiv.1001.2693v1.-- Trabajo presentado al "The International Workshop on Beyond the Standard Model Physics and LHC Signatures (BSM-LHC) celebrado en Boston (USA) del 2 al 4 de junio de 2009.
Heavy Higgs of the Twin Higgs models
2018
Twin Higgs models are the prime illustration of neutral naturalness, where the new particles of the twin sector, gauge singlets of the Standard Model (SM), ameliorate the little hierarchy problem. In this work, we analyse phenomenological implications of the heavy Higgs of the Mirror Twin Higgs and Fraternal Twin Higgs models, when electroweak symmetry breaking is linearly realized. The most general structure of twin Higgs symmetry breaking, including explicit soft and hard breaking terms in the scalar potential, is employed. The direct and indirect searches at the LHC are used to probe the parameter space of Twin Higgs models through mixing of the heavy Higgs with the SM Higgs and decays o…
Search for extra dimensions in diphoton events from proton-proton collisions at root s=7 TeV in the ATLAS detector at the LHC
2013
The large difference between the Planck scale and the electroweak scale, known as the hierarchy problem, is addressed in certain models through the postulate of extra spatial dimensions. A search for evidence of extra spatial dimensions in the diphoton channel has been performed using the full set of proton–proton collisions at √s = 7 TeV recorded in 2011 with the ATLAS detector at the CERN Large Hadron Collider. This dataset corresponds to an integrated luminosity of 4.9fb[superscript −1]. The diphoton invariant mass spectrum is observed to be in good agreement with the Standard Model expectation. In the context of the model proposed by Arkani–Hamed, Dimopoulos and Dvali, 95% confidence le…
Gravitational Wave Echo of Relaxion Trapping
2021
To solve the hierarchy problem, the relaxion must remain trapped in the correct minimum, even if the electroweak symmetry is restored after reheating. In this scenario, the relaxion starts rolling again until the backreaction potential, with its set of local minima, reappears. Depending on the time of barrier reappearance, Hubble friction alone may be insufficient to retrap the relaxion in a large portion of the parameter space. Thus, an additional source of friction is required, which might be provided by coupling to a dark photon.The dark photon experiences a tachyonic instability as the relaxion rolls, which slows down the relaxion by backreacting to its motion, and efficiently creates a…
Cosmology of the Planck Era from a Renormalization Group for Quantum Gravity
2001
Homogeneous and isotropic cosmologies of the Planck era before the classical Einstein equations become valid are studied taking quantum gravitational effects into account. The cosmological evolution equations are renormalization group improved by including the scale dependence of Newton's constant and of the cosmological constant as it is given by the flow equation of the effective average action for gravity. It is argued that the Planck regime can be treated reliably in this framework because gravity is found to become asymptotically free at short distances. The epoch immediately after the initial singularity of the Universe is described by an attractor solution of the improved equations w…
NEUTRINO SPECTRUM IN NONSUPERSYMMETRIC SO(10)
1996
We present a predictive scheme for fermion masses and mixings inspired by nonsupersymmetric SO(10) in which the hierarchy problem is resolved without fine tuning the Yukawa couplings. This calls for a nonminimal Higgs sector which we exploit in deriving the expressions for the mass matrices. To keep the predictivity of the model under control we limit the structure of the mass matrices by imposing U(1) symmetries. A very predictive neutrino spectrum is then obtained.
Ultraviolet complete technicolor and Higgs physics at LHC
2015
We construct a Technicolor model which provides masses for the electroweak gauge bosons and for all the Standard Model matter fields. Starting from an ultraviolet complete supersymmetric technicolor, we propose a scenario where all elementary scalars, gauginos, and higgsinos are decoupled at an energy scale substantially higher than the electroweak scale, therefore avoiding the little hierarchy problem of the minimal supersymmetric standard model. The resulting low energy theory has an SU(3) global symmetry whose breaking to SO(3) leads to electroweak symmetry breaking. We study in detail the phenomenology of this theory and demonstrate that it reproduces the present LHC data at the same le…
Fun with the Abelian Higgs model
2013
In calculations of the elementary scalar spectra of spontaneously broken gauge theories there are a number of subtleties which, though it is often unnecessary to deal with them in the order-of-magnitude type of calculations, have to be taken into account if fully consistent results are sought for. Within the "canonical" effective-potential approach these are, for instance: the need to handle infinite series of nested commutators of derivatives of field-dependent mass matrices, the need to cope with spurious IR divergences emerging in the consistent leading-order approximation and, in particular, the need to account for the fine interplay between the renormalization effects in the one-and tw…
Little Randall-Sundrum models:ϵKstrikes again
2009
A detailed phenomenological analysis of neutral kaon mixing in ``little Randall-Sundrum'' models is presented. It is shown that the constraints arising from the $CP$-violating quantity ${ϵ}_{K}$ can, depending on the value of the ultraviolet cutoff, be even stronger than in the original Randall-Sundrum scenario addressing the hierarchy problem up to the Planck scale. The origin of the enhancement is explained, and a bound ${\ensuremath{\Lambda}}_{\mathrm{UV}}g\mathrm{\text{several}}$ ${10}^{3}\text{ }\text{ }\mathrm{TeV}$ is derived, below which vast corrections to ${ϵ}_{K}$ are generically unavoidable. Implications for nonstandard ${Z}^{0}\ensuremath{\rightarrow}b\overline{b}$ couplings ar…