scholarly journals The serendipity of electroweak baryogenesis

2018 ◽  
Vol 376 (2114) ◽  
pp. 20170124 ◽  
Author(s):  
Géraldine Servant
Keyword(s):  
Particle Physics ◽  
Dipole Moments ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Yukawa Couplings ◽  
Composite Higgs ◽  
The Standard Model ◽  
The Right ◽  
Right Order ◽  
The Universe

The origin of the matter–antimatter asymmetry of the universe remains unexplained in the Standard Model (SM) of particle physics. The origin of the flavour structure is another major puzzle of the theory. In this article, we report on recent work attempting to link the two themes through the appealing framework of electroweak (EW) baryogenesis. We show that Yukawa couplings of SM fermions can be the source of CP violation for EW baryogenesis if they vary at the same time as the Higgs is acquiring its vacuum expectation value, offering new avenues for EW baryogenesis. The advantage of this approach is that it circumvents the usual severe bounds from electric dipole moments. These ideas apply if the mechanism explaining the flavour structure of the SM is connected to EW symmetry breaking, as motivated for instance in Randall–Sundrum or Composite Higgs models. We compute the resulting baryon asymmetry for different configurations of the Yukawa coupling variation across the bubble wall and show that it can naturally be of the right order. This article is part of the Theo Murphy meeting issue ‘Higgs cosmology’.

scholarly journals Cosmological evolution of the proton-to-electron mass ratio in an extended Brans–Dicke theory

2019 ◽  
Vol 34 (34) ◽  
pp. 1950277
Author(s):  
Ahmad Mohamadnejad
Keyword(s):  
Particle Physics ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Energy Scale ◽  
Electron Mass ◽  
Mass Ratio ◽  
Higgs Vacuum ◽  
Proton Mass ◽  
Expansion Of The Universe ◽  
The Universe

We study variation of the proton-to-electron mass ratio [Formula: see text] by incorporating Standard Model (SM) of particle physics into an extended Brans–Dicke theory. We show that the evolution of the Higgs vacuum expectation value (VEV), with expansion of the Universe, leads to the variation of the proton-to-electron mass ratio. This is because the electron mass is proportional to the Higgs VEV, while the proton mass is mainly dependent on the quantum chromodynamics (QCD) energy scale, i.e. [Formula: see text]. Therefore, using the experimental and cosmological constraints on the variation of the [Formula: see text], we can constrain the variation of the Higgs VEV. This study is important in understanding the recent claims of the detection of a variation of the proton-to-electron mass ratio in quasar absorption spectra.

scholarly journals Evidence of the big fix

2014 ◽  
Vol 29 (17) ◽  
pp. 1450099 ◽  
Author(s):  
Yuta Hamada ◽  
Hikaru Kawai ◽  
Kiyoharu Kawana
Keyword(s):  
Maximum Entropy Principle ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Baryon Number ◽  
Quark Masses ◽  
Atomic Nuclei ◽  
The Standard Model ◽  
Entropy Principle ◽  
Fundamental Law ◽  
The Universe

We give an evidence of the Big Fix. The theory of wormholes and multiverse suggests that the parameters of the Standard Model are fixed in such a way that the total entropy at the late stage of the universe is maximized, which we call the maximum entropy principle. In this paper, we discuss how it can be confirmed by the experimental data, and we show that it is indeed true for the Higgs vacuum expectation value vh. We assume that the baryon number is produced by the sphaleron process, and that the current quark masses, the gauge couplings and the Higgs self-coupling are fixed when we vary vh. It turns out that the existence of the atomic nuclei plays a crucial role to maximize the entropy. This is reminiscent of the anthropic principle, however it is required by the fundamental law in our case.

scholarly journals Exact SMEFT formulation and expansion to $$ \mathcal{O} $$(v4/Λ4)

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Chris Hays ◽  
Andreas Helset ◽  
Adam Martin ◽  
Michael Trott
Keyword(s):  
Standard Model ◽  
Particle Physics ◽  
Input Parameter ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
New Physics ◽  
Specific Model ◽  
Effective Field ◽  
The Standard Model ◽  
Mass Dimension

Abstract The Standard Model Effective Field Theory (SMEFT) theoretical framework is increasingly used to interpret particle physics measurements and constrain physics beyond the Standard Model. We investigate the truncation of the effective-operator expansion using the geometric formulation of the SMEFT, which allows exact solutions, up to mass-dimension eight. Using this construction, we compare the exact solution to the expansion at $$ \mathcal{O} $$ O (v2/Λ2), partial $$ \mathcal{O} $$ O (v4/Λ4) using a subset of terms with dimension-6 operators, and full $$ \mathcal{O} $$ O (v4/Λ4), where v is the vacuum expectation value and Λ is the scale of new physics. This comparison is performed for general values of the coefficients, and for the specific model of a heavy U(1) gauge field kinetically mixed with the Standard Model. We additionally determine the input-parameter scheme dependence at all orders in v/Λ, and show that this dependence increases at higher orders in v/Λ.

scholarly journals EDM Experiments at Storage Rings

2018 ◽  
Vol 181 ◽  
pp. 01031
Author(s):  
Hans Ströher
Keyword(s):  
Particle Physics ◽  
Dipole Moments ◽  
Polarization Vector ◽  
Storage Rings ◽  
Ongoing Research ◽  
New Class ◽  
Double Beam ◽  
The Standard Model ◽  
Measurement Principle ◽  
The Universe

According to our present understanding, the early Universe contained the same amount of matter and anti-matter and, if the Universe had behaved symmetrically as it developed, every particle would have been annihilated by one of its antiparticles. One of the great mysteries in the natural sciences is therefore, why matter dominates over antimatter in the visible Universe. The breaking of the combined chargeconjugation and parity symmetries (CP-violation, CPV) in the Standard Model of particle physics (SM) is insufficient to explain this and further sources of CPV must be sought. These could manifest themselves in electric dipole moments (EDMs) of elementary particles, which occur when the centroids of positive and negative charges are mutually and permanently displaced. An EDM observation would also be an indication for physics beyond the SM. No EDM has been observed so far; after its discovery, investigations on different systems will be required to pin down CPV sources. In this respect the idea to search for EDMs of charged hadrons (i.p. proton and deuteron) in a new class of precision storage rings has recently been put forward. In addition, such searches bear the potential to reach sensitivities of 10-29 e·cm. The EDM measurement principle, the time development of the polarization vector subject to a perpendicular electric field, is simple, but the smallness of the effect makes this an enormously challenging project. A stepwise approach, from R&D for key-technologies towards the holy grail of a double-beam precision storage ring with counter-rotating beams, is needed. The ongoing research of the JEDI Collaboration at the cooler synchrotron COSY of Forschungszentrum Jülich (Germany) provides invaluable information: recent experimental milestones are presented and discussed.

scholarly journals Charged lepton flavor violating processes in neutrinophilic Higgs + seesaw model

2020 ◽  
Vol 2020 (7) ◽  
Author(s):  
Naoyuki Haba ◽  
Tsuneharu Omija ◽  
Toshifumi Yamada
Keyword(s):  
Charged Lepton ◽  
Higgs Field ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Charged Scalar ◽  
Yukawa Couplings ◽  
Scalar Particles ◽  
Lepton Flavor ◽  
Seesaw Model ◽  
The Right

Abstract We investigate charged lepton flavor violating (CLFV) processes in the “neutrinophilic Higgs + seesaw model”, in which right-handed neutrinos couple only with an extra Higgs field which develops a tiny vacuum expectation value and the right-handed neutrinos also have Majorana mass. The model realizes a seesaw mechanism around TeV scale without extremely small Dirac Yukawa couplings. A phenomenological feature of the model is CLFV processes induced by loop diagrams of the charged scalar particles and heavy neutrinos. Therefore, first we constrain the model’s parameter space from the search for $\mu\to e\gamma$. Next, we predict the branching ratios of other CLFV processes including the $\mu\to3e$, $\mu+{\rm Al}\to e+{\rm Al}$, $\mu+{\rm Ti}\to e+{\rm Ti}$, $Z\to e\mu$, $Z\to e\tau$, $Z\to \mu\tau$, $h\to e\tau$ and $h\to\mu\tau$ processes, and discuss their detectability in future experiments.

An Interview with the Physicist that Her Head in the Universe and Both Feet on the Earth

2019 ◽  
Author(s):  
Adib Rifqi Setiawan
Keyword(s):  
Standard Model ◽  
Particle Physics ◽  
Space Time ◽  
Additional Dimension ◽  
The Earth ◽  
The Standard Model ◽  
The Universe

Put simply, Lisa Randall’s job is to figure out how the universe works, and what it’s made of. Her contributions to theoretical particle physics include two models of space-time that bear her name. The first Randall–Sundrum model addressed a problem with the Standard Model of the universe, and the second concerned the possibility of a warped additional dimension of space. In this work, we caught up with Randall to talk about why she chose a career in physics, where she finds inspiration, and what advice she’d offer budding physicists. This article has been edited for clarity. My favourite quote in this interview is, “Figure out what you enjoy, what your talents are, and what you’re most curious to learn about.” If you insterest in her work, you can contact her on Twitter @lirarandall.

An Interview with the Physicist that Her Head in the Universe and Both Feet on the Earth

2019 ◽  
Author(s):  
Adib Rifqi Setiawan
Keyword(s):  
Standard Model ◽  
Particle Physics ◽  
Space Time ◽  
Additional Dimension ◽  
The Earth ◽  
The Standard Model ◽  
The Universe

Put simply, Lisa Randall’s job is to figure out how the universe works, and what it’s made of. Her contributions to theoretical particle physics include two models of space-time that bear her name. The first Randall–Sundrum model addressed a problem with the Standard Model of the universe, and the second concerned the possibility of a warped additional dimension of space. In this work, we caught up with Randall to talk about why she chose a career in physics, where she finds inspiration, and what advice she’d offer budding physicists. This article has been edited for clarity. My favourite quote in this interview is, “Figure out what you enjoy, what your talents are, and what you’re most curious to learn about.” If you insterest in her work, you can contact her on Twitter @lirarandall.

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 Fermion mass hierarchies from supersymmetric gauged flavour symmetry in 5D

2021 ◽  
Vol 10 (6) ◽  
Author(s):  
Ketan Patel
Keyword(s):  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Fermion Mass ◽  
Order Unity ◽  
Anomaly Cancellation ◽  
Fundamental Parameters ◽  
Yukawa Couplings ◽  
Fifth Dimension ◽  
Fermion Masses ◽  
The Masses

A mechanism to generate realistic fermion mass hierarchies based on supersymmetric gauged U(1)_FU(1)F symmetry in flat five-dimensional (5D) spacetime is proposed. The fifth dimension is compactified on S^1/Z_2S1/Z2 orbifold. The standard model fermions charged under the extra abelian symmetry along with their superpartners live in the 5D bulk. Bulk masses of fermions are generated by the vacuum expectation value of N=2N=2 superpartner of U(1)_FU(1)F gauge field, and they are proportional to U(1)_FU(1)F charges of respective fermions. This decides localization of fermions in the extra dimension, which in turn gives rise to exponentially suppressed Yukawa couplings in the effective 4D theory. Anomaly cancellation puts stringent constraints on the allowed U(1)_FU(1)F charges which leads to correlations between the masses of quarks and leptons. We perform an extensive numerical scan and obtain several solutions for anomaly-free U(1)_FU(1)F, which describe the observed pattern of fermion masses and mixing with all the fundamental parameters of order unity. It is found that the possible existence of SM singlet neutrinos substantially improves the spectrum of solutions by offering more freedom in choosing U(1)_FU(1)F charges. The model predicts Z^\primeZ′ boson mediating flavour violating interactions in both the quark and lepton sectors with the couplings which can be explicitly determined from the Yukawa couplings.

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