Bubble Expansion and the Viability of Singlet-Driven Electroweak Baryogenesis
TL;DR: In this paper, the friction on the bubble wall is computed using a kinetic theory approach and including hydrodynamic effects, and the velocities are found to be rather large, but compatible with electroweak baryogenesis in some portions of the parameter space.
Abstract: The standard picture of electroweak baryogenesis requires slowly expanding bubbles. This can be difficult to achieve if the vacuum expectation value of a gauge singlet scalar field changes appreciably during the electroweak phase transition. It is important to determine the bubble wall velocity in this case, since the predicted baryon asymmetry can depend sensitively on its value. Here, this calculation is discussed and illustrated in the real singlet extension of the Standard Model. The friction on the bubble wall is computed using a kinetic theory approach and including hydrodynamic effects. Wall velocities are found to be rather large ($v_w \gtrsim 0.2$) but compatible with electroweak baryogenesis in some portions of the parameter space. If the phase transition is strong enough, however, a subsonic solution may not exist, precluding non-local electroweak baryogenesis altogether. The results presented here can be used in calculating the baryon asymmetry in various singlet-driven scenarios, as well as other features related to cosmological phase transitions in the early Universe, such as the resulting spectrum of gravitational radiation.
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TL;DR: In this paper, the authors investigated the potential for the eLISA space-based interferometer to detect the stochastic gravitational wave background produced by strong first-order cosmological phase transitions.
Abstract: We investigate the potential for the eLISA space-based interferometer to detect the stochastic gravitational wave background produced by strong first-order cosmological phase transitions. We discuss the resulting contributions from bubble collisions, magnetohydrodynamic turbulence, and sound waves to the stochastic background, and estimate the total corresponding signal predicted in gravitational waves. The projected sensitivity of eLISA to cosmological phase transitions is computed in a model-independent way for various detector designs and configurations. By applying these results to several specific models, we demonstrate that eLISA is able to probe many well-motivated scenarios beyond the Standard Model of particle physics predicting strong first-order cosmological phase transitions in the early Universe.
352 citations
TL;DR: In this article, the correlation between the baryon-to-entropy ratio produced by electroweak baryogenesis and the gravitational wave signal from the electroweak phase transition was studied.
Abstract: We consider a real scalar singlet field which provides a strong first-order electroweak phase transition via its coupling to the Higgs boson, and gives a $CP$ violating contribution on the top quark mass via a dimension-6 operator. We study the correlation between the baryon-to-entropy ratio produced by electroweak baryogenesis, and the gravitational wave signal from the electroweak phase transition. We show that future gravitational wave experiments can test, in particular, the region of the model parameter space where the observed baryon-to-entropy ratio can be obtained even if the new physics scale, which is explicit in the dimension-6 operator, is high.
196 citations
TL;DR: In this paper, the authors survey a few classes of models in which the electroweak phase transition is strongly first order and identify the observables that would provide evidence of these models at the LHC and next generation lepton colliders, and assess whether the corresponding gravitational wave signal could be detected by eLISA.
Abstract: After the discovery of the Higgs boson, understanding the nature of electroweak symmetry breaking and the associated electroweak phase transition has become the most pressing question in particle physics. Answering this question is a priority for experimental studies. Data from the LHC and future lepton collider-based Higgs factories may uncover new physics coupled to the Higgs boson, which can induce the electroweak phase transition to become first order. Such a phase transition generates a stochastic background of gravitational waves, which could potentially be detected by a space-based gravitational wave interferometer. In this paper, we survey a few classes of models in which the electroweak phase transition is strongly first order. We identify the observables that would provide evidence of these models at the LHC and next-generation lepton colliders, and we assess whether the corresponding gravitational wave signal could be detected by eLISA. We find that most of the models with first-order electroweak phase transition can be covered by the precise measurements of Higgs couplings at the proposed Higgs factories. We also map out the model space that can be probed with gravitational wave detection by eLISA.
171 citations
Heidelberg University1, Vanderbilt University2, Imperial College London3, Queen Mary University of London4, Johns Hopkins University5, Princeton University6, Peking University7, University of Tübingen8, City University of New York9, American Museum of Natural History10, Northwestern University11, University of Wisconsin-Madison12, University of Florida13, Stevens Institute of Technology14, University of Stavanger15, Stockholm University16, University of Milan17, Albert Einstein Institution18, University of California, Berkeley19, King's College London20
TL;DR: The decihertz band is uniquely suited to observation of intermediate-mass black holes as discussed by the authors, which may form the missing link between stellar-mass and massive black holes, offering a unique opportunity to measure their properties.
Abstract: The gravitational-wave astronomical revolution began in 2015 with LIGO's observation of the coalescence of two stellar-mass black holes. Over the coming decades, ground-based detectors like LIGO will extend their reach, discovering thousands of stellar-mass binaries. In the 2030s, the space-based LISA will enable gravitational-wave observations of the massive black holes in galactic centres. Between LISA and ground-based observatories lies the unexplored decihertz gravitational-wave frequency band. Here, we propose a Decihertz Observatory to cover this band, and complement observations made by other gravitational-wave observatories. The decihertz band is uniquely suited to observation of intermediate-mass ($\sim 10^2$-$10^4 M_\odot$) black holes, which may form the missing link between stellar-mass and massive black holes, offering a unique opportunity to measure their properties. Decihertz observations will be able to detect stellar-mass binaries days to years before they merge and are observed by ground-based detectors, providing early warning of nearby binary neutron star mergers, and enabling measurements of the eccentricity of binary black holes, providing revealing insights into their formation. Observing decihertz gravitational-waves also opens the possibility of testing fundamental physics in a new laboratory, permitting unique tests of general relativity and the Standard Model of particle physics. Overall, a Decihertz Observatory will answer key questions about how black holes form and evolve across cosmic time, open new avenues for multimessenger astronomy, and advance our understanding of gravitation, particle physics and cosmology.
66 citations
TL;DR: In this article, the authors analyze the collider signatures of the real singlet extension of the Standard Model in regions consistent with a strong first-order electroweak phase transition and a singlet-like scalar heavier than the standard model-like Higgs.
Abstract: We analyze the collider signatures of the real singlet extension of the Standard Model in regions consistent with a strong first-order electroweak phase transition and a singlet-like scalar heavier than the Standard Model-like Higgs. A definitive correlation exists between the strength of the phase transition and the trilinear coupling of the Higgs to two singlet-like scalars, and hence between the phase transition and non-resonant scalar pair production involving the singlet at colliders. We study the prospects for observing these processes at the LHC and a future 100 TeV $pp$ collider, focusing particularly on double singlet production. We also discuss correlations between the strength of the electroweak phase transition and other observables at hadron and future lepton colliders. Searches for non-resonant singlet-like scalar pair production at 100 TeV would provide a sensitive probe of the electroweak phase transition in this model, complementing resonant di-Higgs searches and precision measurements. Our study illustrates a strategy for systematically exploring the phenomenologically viable parameter space of this model, which we hope will be useful for future work.
21 citations
Cites background from "Bubble Expansion and the Viability ..."
...Also, singlet models are known to suffer from fast bubble walls [105, 106]: if the bubble wall velocity in the plasma frame is larger than the sound speed, the conventional picture of non-local electroweak baryogenesis cannot occur,9 which would again likely exclude some regions with large barriers (although these points are often interesting from the standpoint of observable gravitational radiation [20])....
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References
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TL;DR: In this article, a search for the Standard Model Higgs boson in proton-proton collisions with the ATLAS detector at the LHC is presented, which has a significance of 5.9 standard deviations, corresponding to a background fluctuation probability of 1.7×10−9.
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TL;DR: In this paper, results from searches for the standard model Higgs boson in proton-proton collisions at 7 and 8 TeV in the CMS experiment at the LHC, using data samples corresponding to integrated luminosities of up to 5.8 standard deviations.
8,857 citations
TL;DR: In this article, the decay of a false vacuum in a single scalar field with nonderivative interactions is studied. But the decay is not restricted to the case of singular fields.
Abstract: It is possible for a classical field theory to have two homogeneous stable equilibrium states with different energy densities. In the quantum version of the theory, the state of higher energy density becomes unstable through barrier penetration; it is a false vacuum. This is the first of two papers developing the qualitative and quantitative semiclassical theory of the decay of such a false vacuum for theories of a single scalar field with nonderivative interactions. In the limit of vanishing energy density between the two ground states, it is possible to obtain explicit expressions for the relevant quantities to leading order in $h$; in the more general case, the problem can be reduced to solving a single nonlinear ordinary differential equation.
1,929 citations
TL;DR: In this paper, the decay of a false vacuum in a single scalar field with nonderivative interactions is studied. But the decay is not restricted to a single field theory.
Abstract: It is possible for a classical field theory to have two homogeneous stable equilibrium states with different energy densities. In the quantum version of the theory, the state of higher energy density becomes unstable through barrier penetration; it is a false vacuum. This is the first of two papers developing the qualitative and quantitative semiclassical theory of the decay of such a false vacuum for theories of a single scalar field with nonderivative interactions. In the limit of vanishing energy density between the two ground states, it is possible to obtain explicit expressions for the relevant quantities to leading order in h; in the more general case, the problem can be reduced to solving a single nonlinear ordinary differential equation.
1,654 citations
TL;DR: The Cuba library provides new implementations of four general-purpose multidimensional integration algorithms: Vegas, Suave, Divonne, and Cuhre, which can integrate vector integrands and have very similar Fortran, C/C++, and Mathematica interfaces.
916 citations
"Bubble Expansion and the Viability ..." refers methods in this paper
...[118, 121, 125] and the Vegas Monte Carlo routine included in the Cuba package [126]....
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