scholarly journals Clues on the Majorana scale from scalar resonances at the LHC

2017 ◽  
Vol 32 (06) ◽  
pp. 1750035 ◽  
Author(s):  
Oliver Fischer
Keyword(s):  
Hadron Collider ◽  
Planck Scale ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
High Energy ◽  
Mass Scale ◽  
Particle Spectrum ◽  
Neutrino Sector ◽  
Decay Properties ◽  
The Hill

In order to address the observation of the neutrino oscillations and the metastability of the Standard Model (SM), we extend the fermion sector with two right-handed (i.e. sterile) neutrinos, and the scalar sector of the SM with a real scalar, the Hill field. The latter takes the role of a Majoron and generates the Majorana masses for the neutrino sector, such that the particle spectrum features two CP-even scalars h1 and h2, and also two heavy, mass degenerate neutrinos. When the h1 is identified with the scalar resonance at [Formula: see text] 125 GeV and the condition is imposed that the h1 self-coupling and its running vanish at the Planck scale, the scalar mixing and the vacuum expectation value of the Hill field are fixed by the h2 mass. The h2 can be searched for at the LHC, and it has prospects of being discovered for the target integrated luminosities of the HL-LHC and the Future Circular hadron Collider (FCC-hh) when its mass is on the weak scale. The knowledge of the h2 mass and its decay properties can yield an insight into its coupling to the heavy neutrinos, and thus also on the heavy neutrino mass scale. This yields an interesting connection between potentially detectable heavy scalars in high-energy proton collisions and the mass scale of the heavy neutrinos that is testable at the LHC and at future colliders.

scholarly journals Weak scale from Planck scale: Mass scale generation in a classically conformal two-scalar system

2020 ◽  
Vol 2020 (3) ◽  
Author(s):  
Junichi Haruna ◽  
Hikaru Kawai
Keyword(s):  
Scalar Field ◽  
Standard Model ◽  
Planck Scale ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
The Other ◽  
Expectation Value ◽  
Weak Scale ◽  
The Standard Model ◽  
The One

Abstract In the standard model, the weak scale is the only parameter with mass dimensions. This means that the standard model itself cannot explain the origin of the weak scale. On the other hand, from the results of recent accelerator experiments, except for some small corrections, the standard model has increased the possibility of being an effective theory up to the Planck scale. From these facts, it is naturally inferred that the weak scale is determined by some dynamics from the Planck scale. In order to answer this question, we rely on the multiple point criticality principle as a clue and consider the classically conformal $\mathbb{Z}_2\times \mathbb{Z}_2$ invariant two-scalar model as a minimal model in which the weak scale is generated dynamically from the Planck scale. This model contains only two real scalar fields and does not contain any fermions or gauge fields. In this model, due to a Coleman–Weinberg-like mechanism, the one-scalar field spontaneously breaks the $ \mathbb{Z}_2$ symmetry with a vacuum expectation value connected with the cutoff momentum. We investigate this using the one-loop effective potential, renormalization group and large-$N$ limit. We also investigate whether it is possible to reproduce the mass term and vacuum expectation value of the Higgs field by coupling this model with the standard model in the Higgs portal framework. In this case, the one-scalar field that does not break $\mathbb{Z}_2$ can be a candidate for dark matter and have a mass of about several TeV in appropriate parameters. On the other hand, the other scalar field breaks $\mathbb{Z}_2$ and has a mass of several tens of GeV. These results will be verifiable in near-future experiments.

scholarly journals Triply charged Higgs bosons at a 100 TeV pp collider

2021 ◽  
Vol 81 (1) ◽  
Author(s):  
Junxing Pan ◽  
Jung-Hsin Chen ◽  
Xiao-Gang He ◽  
Gang Li ◽  
Jhih-Ying Su
Keyword(s):  
Higgs Boson ◽  
Hadron Collider ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Mass Splitting ◽  
Charged Higgs Boson ◽  
Higgs Bosons ◽  
Boson Mass ◽  
Final State ◽  
Charged Higgs

AbstractIn this work, we study the potential of searching for triply charged Higgs boson originating from a complex Higgs quadruplet in the final state with at least three same-sign leptons. A detailed collider analysis of the SM backgrounds and signals is performed at a 100 TeV pp collider for the triply charged Higgs boson mass below 1 TeV and the Higgs quadruplet vacuum expectation value $$v_\Delta $$ v Δ ranging from $$1.5\times 10^{-9}~\text {GeV}$$ 1.5 × 10 - 9 GeV to $$1.3~\text {GeV}$$ 1.3 GeV and the mass splitting $$\Delta m$$ Δ m between the nearby states of the Higgs quadruplet satisfying $$|\Delta m|\lesssim 30~\text {GeV}$$ | Δ m | ≲ 30 GeV . About $$100~\text {fb}^{-1}$$ 100 fb - 1 of data are required at most for $$5\sigma $$ 5 σ discovery. We also revisit the sensitivity at the Large Hadron Collider (LHC) and find that $$5\sigma $$ 5 σ discovery of the triply charged Higgs boson below 1 TeV can be reached for a relatively small $$v_\Delta $$ v Δ . For example, if $$v_\Delta =10^{-6}~\text {GeV}$$ v Δ = 10 - 6 GeV and $$\Delta m=0$$ Δ m = 0 , the integrated luminosity of $$330~\text {fb}^{-1}$$ 330 fb - 1 is needed. But for a relatively large $$v_\Delta $$ v Δ , i.e., $$v_\Delta \gtrsim 10^{-3}~\text {GeV}$$ v Δ ≳ 10 - 3 GeV , the triply charged Higgs boson above about 800 GeV cannot be discovered even in the high-luminosity LHC era. For $$\Delta m>0$$ Δ m > 0 , the cascade decays are open and the sensitivity can be improved depending on the value of $$v_\Delta $$ v Δ .

scholarly journals Scale-invariance, dynamically induced Planck scale and inflation in the Palatini formulation

2021 ◽  
Vol 2105 (1) ◽  
pp. 012005
Author(s):  
Ioannis D. Gialamas ◽  
Alexandros Karam ◽  
Thomas D. Pappas ◽  
Antonio Racioppi ◽  
Vassilis C. Spanos
Keyword(s):  
Scale Invariance ◽  
Planck Scale ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Scalar Fields ◽  
Scale Invariant ◽  
Expectation Value ◽  
Hilbert Action

Abstract We present two scale invariant models of inflation in which the addition of quadratic in curvature terms in the usual Einstein-Hilbert action, in the context of Palatini formulation of gravity, manages to reduce the value of the tensor-to-scalar ratio. In both models the Planck scale is dynamically generated via the vacuum expectation value of the scalar fields.

scholarly journals SPONTANEOUS VIOLATION OF LORENTZ INVARIANCE AND ULTRA-HIGH ENERGY COSMIC RAYS

2003 ◽  
Vol 12 (07) ◽  
pp. 1279-1287 ◽  
Author(s):  
J. W. MOFFAT
Keyword(s):  
Cosmic Rays ◽  
Lorentz Invariance ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
High Energy ◽  
Spontaneous Breaking ◽  
Ultra High Energy ◽  
High Energy Cosmic Rays ◽  
High Energies ◽  
Local Lorentz Invariance

We propose that local Lorentz invariance is spontaneously violated at high energies, due to a nonvanishing vacuum expectation value of a vector field ϕμ, as a possible explanation of the observation of ultra-high energy cosmic rays with an energy above the GZK cutoff. Certain consequences of spontaneous breaking of Lorentz invariance in cosmology are discussed.

scholarly journals Natural relaxation

2016 ◽  
Vol 31 (39) ◽  
pp. 1650215 ◽  
Author(s):  
Luca Marzola ◽  
Martti Raidal
Keyword(s):  
Hadron Collider ◽  
Planck Scale ◽  
Vacuum State ◽  
Relaxation Mechanism ◽  
Mass Scale ◽  
Boson Mass ◽  
Inflationary Cosmology ◽  
Vacuum Stability ◽  
Seesaw Mechanism ◽  
The One

Motivated by natural inflation, we propose a relaxation mechanism consistent with inflationary cosmology that explains the hierarchy between the electroweak scale and Planck scale. This scenario is based on a selection mechanism that identifies the low-scale dynamics as the one that is screened from UV physics. The scenario also predicts the near-criticality and metastability of the Standard Model (SM) vacuum state, explaining the Higgs boson mass observed at the Large Hadron Collider (LHC). Once Majorana right-handed neutrinos are introduced to provide a viable reheating channel, our framework yields a corresponding mass scale that allows for the seesaw mechanism as well as for standard thermal leptogenesis. We argue that considering singlet scalar dark matter extensions of the proposed scenario could solve the vacuum stability problem and discuss how the cosmological constant problem is possibly addressed.

scholarly journals Unified emergence of energy scales and cosmic inflation

2021 ◽  
Vol 2021 (8) ◽  
Author(s):  
Jisuke Kubo ◽  
Jeffrey Kuntz ◽  
Manfred Lindner ◽  
Jonas Rezacek ◽  
Philipp Saake ◽  
...  
Keyword(s):  
Scale Invariance ◽  
Planck Scale ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Spontaneous Breaking ◽  
Type I ◽  
Cosmic Inflation ◽  
Dynamical Generation ◽  
Majorana Neutrinos ◽  
Relic Abundance

Abstract In the quest for unification of the Standard Model with gravity, classical scale invariance can be utilized to dynamically generate the Planck mass MPl. However, the relation of Planck scale physics to the scale of electroweak symmetry breaking μH requires further explanation. In this paper, we propose a model that uses the spontaneous breaking of scale invariance in the scalar sector as a unified origin for dynamical generation of both scales. Using the Gildener-Weinberg approximation, only one scalar acquires a vacuum expectation value of υS ∼ (1016−17) GeV, thus radiatively generating $$ {M}_{\mathrm{P}1}\approx {\beta}_S^{1/2}{\upsilon}_S $$ M P 1 ≈ β S 1 / 2 υ S and μH via the neutrino option with right handed neutrino masses mN = yMυS ∼ 107 GeV. Consequently, active SM neutrinos are given a mass with the inclusion of a type-I seesaw mechanism. Furthermore, we adopt an unbroken Z2 symmetry and a Z2-odd set of right-handed Majorana neutrinos χ that do not take part in the neutrino option and are able to produce the correct dark matter relic abundance (dominantly) via inflaton decay. The model also describes cosmic inflation and the inflationary CMB observables are predicted to interpolate between those of R2 and linear chaotic inflationary model and are thus well within the strongest experimental constraints.

scholarly journals Exotic Higgs decays into displaced jets at the LHeC

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Kingman Cheung ◽  
Oliver Fischer ◽  
Zeren Simon Wang ◽  
Jose Zurita
Keyword(s):  
Higgs Boson ◽  
Parameter Space ◽  
Hadron Collider ◽  
Percent Level ◽  
Branching Ratio ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Decay Length ◽  
Decay Modes ◽  
Scalar Particles

Abstract Profiling the Higgs boson requires the study of its non-standard decay modes. In this work we discuss the prospects of the Large Hadron electron Collider (LHeC) to detect scalar particles with masses ,≳ 10 GeV produced from decays of the Standard Model (SM) Higgs boson. These scalar particles decay mainly to bottom pairs, and in a vast portion of the allowed parameter space they acquire a macroscopic lifetime, hence giving rise to displaced hadronic vertices. The LHeC provides a very clean environment that allows for easy identification of these final states, in contrast to hadronic colliders where the overwhelming backgrounds and high pile-up render such searches incredibly challenging. We find that the LHeC provides a unique window of opportunity to detect scalar particles with masses between 10 and 30 GeV. In the Higgs Portal scenarios we can test the mixing angle squared, sin2α, as low as 10−5–10−7, with the exact value depending on the vacuum expectation value of the new scalar.Our results are also presented in a model-independent fashion in the lifetime-branching ratio and mass-branching ratio planes. We have found that exotic branching ratios of the Higgs boson at the sub-percent level can be probed, for the scalar decay length in the range 10−4 m ≲ cτ ≲ 10−1 m. The expected coverage of the parameter space largely exceeds the published sensitivity of the indirect reach at the high-luminosity Large Hadron Collider via the invisible Higgs branching ratio.

scholarly journals COSMOLOGICAL CONCORDANCE MODEL WITH PARTICLE CREATION

2012 ◽  
Vol 18 ◽  
pp. 38-47
Author(s):  
SAULO CARNEIRO
Keyword(s):  
Vacuum Energy ◽  
Particle Creation ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
High Energy ◽  
Vacuum Energy Density ◽  
Late Time ◽  
Energy Limit ◽  
Scale Invariant ◽  
Expectation Value

The creation of ultra-light dark particles in the late-time FLRW spacetime provides a cosmological model in accordance with precise observational tests. The matter creation backreaction implies in this context a vacuum energy density scaling linearly with the Hubble parameter H, which is consistent with the vacuum expectation value of the QCD condensate in a low-energy expanding spacetime. Both the cosmological constant and coincidence problems are alleviated in this scenario. We also explore the opposite, high energy limit of the particle creation process. We show that it leads to a non-singular primordial universe where an early inflationary era takes place, with natural reheating and exit. The generated primordial spectrum is scale invariant and, by supposing that inflation lasts for 60 e-folds, we obtain a scalar expectral index n ≈ 0.97.

Doubly and singly charged Higgs pair production at high-energy e+e− linear colliders

2016 ◽  
Vol 31 (10) ◽  
pp. 1650051 ◽  
Author(s):  
Jun Cao ◽  
Xi-Yan Tian
Keyword(s):  
Pair Production ◽  
Linear Collider ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
High Energy ◽  
Higgs Bosons ◽  
Decay Modes ◽  
Charged Higgs ◽  
Triplet Model ◽  
Singly Charged

The Higgs triplet model predicts the existence of the doubly and singly charged Higgs bosons ([Formula: see text] and [Formula: see text]), whose decay modes are relevant to the vacuum expectation value of the triplet [Formula: see text] and the mass spectrum of these scalars. In this paper, we study the pair production of [Formula: see text] via the processes in [Formula: see text] collisions: [Formula: see text] and [Formula: see text]. The numerical results show that the production rates can reach the level of several fb with a center of energy at the TeV scale. The characteristic signals and relevant SM backgrounds are also discussed in both the degenerate and nondegenerate cases. In most of the parameter spaces, their possible signals might be detected via these processes in the future high-energy linear collider experiments with [Formula: see text] and [Formula: see text].

scholarly journals DAMPE excess from decaying right-handed neutrino dark matter

2018 ◽  
Vol 33 (27) ◽  
pp. 1850157 ◽  
Author(s):  
Nobuchika Okada ◽  
Osamu Seto
Keyword(s):  
Dark Matter ◽  
Mass Formula ◽  
Hadron Collider ◽  
Planck Scale ◽  
Gauge Coupling ◽  
Dark Matter Particle ◽  
Cosmic Ray ◽  
High Energy ◽  
Boson Mass ◽  
Late Time

The flux of high-energy cosmic-ray electrons plus positrons recently measured by the DArk Matter Particle Explorer (DAMPE) exhibits a tentative peak excess at an energy of around 1.4 TeV. In this paper, we consider the minimal gauged U(1)[Formula: see text] model with a right-handed neutrino (RHN) dark matter (DM) and interpret the DAMPE peak with a late-time decay of the RHN DM into [Formula: see text]. We find that a DM lifetime [Formula: see text] can fit the DAMPE peak with a DM mass [Formula: see text]. This favored lifetime is close to the current bound on it by Fermi-LAT, our decaying RHN DM can be tested, once the measurement of cosmic gamma ray flux is improved. The RHN DM communicates with the Standard Model particles through the U(1)[Formula: see text] gauge boson ([Formula: see text] boson), and its thermal relic abundance is controlled by only three free parameters: [Formula: see text], the U(1)[Formula: see text] gauge coupling [Formula: see text], and the [Formula: see text] boson mass [Formula: see text]. For [Formula: see text], the rest of the parameters are restricted to be [Formula: see text] and [Formula: see text], in order to reproduce the observed DM relic density and to avoid the Landau pole for running [Formula: see text] below the Planck scale. This allowed region will be tested by the search for a [Formula: see text] boson resonance at the future Large Hadron Collider.

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