Affleck-Dine Baryogenesis Research Articles

Dark matter via baryogenesis: Affleck–Dine mechanism in the minimal supersymmetric standard model

We conducted an investigation into Affleck–Dine baryogenesis within the context of polynomial inflation, specifically focusing on its relationship with a recent reheating formalism. It was found that by considering a specific reheating temperature, the observed baryon asymmetry can be accounted through Affleck–Dine baryogenesis. Additionally, the majority of gravitinos are inferred to be generated from the decay of the next-to-lightest supersymmetric particle, with Q-balls potentially serving as a source of gravitinos via the NSP decay. The temperature at which decay occurs depends on the charge of the Q-balls, which is determined by the fragmentation of the Affleck–Dine condensate. Remarkably, the gravitino mass required for dark matter aligns naturally with the theoretical gravitino mass.

Antistars as possible sources of antihelium cosmic rays

A minor population of antistars in galaxies has been predicted by some of non-standard models of baryogenesis and nucleosynthesis in the early Universe, and their presence is not yet excluded by the currently available observations. Detection of an unusually high abundance of antinuclei in cosmic rays can probe the baryogenesis scenarios in the early Universe. Recent report of the AMS-02 collaboration on the tentative detection of a few antihelium nuclei in GeV cosmic rays provided a great hope on the progress in this issue. We discuss possible sources of antinuclei in cosmic rays from antistars which are predicted in a modified Affleck-Dine baryogenesis scenario by Dolgov and Silk (1993). The model allows us to estimate the expected fluxes and isotopic content of antinuclei in the GeV cosmic rays produced in scenarios involving antistars. We show that the flux of antihelium CRs reported by the AMS-02 experiment can be explained by Galactic anti-nova outbursts, thermonuclear anti-SN Ia explosions, a collection of flaring antistars, or an extragalactic source with abundances not violating existing gamma-ray and microlensing constraints on the antistar population.

Revisiting the Affleck-Dine mechanism for primordial black hole formation

We study a primordial black hole (PBH) formation scenario based on the Affleck-Dine (AD) mechanism and investigate two PBH mass regions: M ∼ 30 M ⊙ motivated by the LIGO-Virgo observations of the binary black hole mergers and M ≳ 104 M ⊙ motivated by the observations of supermassive black holes at the center of galaxies. In the previous studies, it has been considered that the inhomogeneous AD baryogenesis generates regions with a large baryon asymmetry, some of which collapse into PBHs. In this paper, we show that this scenario is severely constrained due to the baryon asymmetry remaining outside PBHs, which would spoil the success of the big bang nucleosynthesis. Then, we propose an alternative scenario where the AD leptogenesis results in the inhomogeneous formation of Q-balls with lepton charges, which collapse into PBHs. As a result, we find that our scenario can explain the favorable PBH abundance without conflicting with the observational constraints.

Freeze-In of radiative keV-scale neutrino dark matter from a new U(1)B-L

We extend the Dirac Scotogenic model with the aim of realizing neutrino masses together with the mass of a keV-scale dark matter (DM) candidate via the same one-loop topology. Two of the Standard Model (SM) neutrinos become massive Dirac fermions while the third one remains massless. Our particle content is motivated by an anomaly free U(1)B-L gauge symmetry with exotic irrational charges and we need to enforce an additional mathcal{Z} 5 symmetry. The dark matter candidate does not mix with the active neutrinos and does not have any decay modes to SM particles. DM is produced together with dark radiation in the form of right handed neutrinos via out of equilibrium annihilations of the SM fermions mediated by the heavy B-L gauge boson. In order to avoid DM over-production from Higgs decays and to comply with Lyman-α bounds we work in a low temperature reheating scenario with 4 MeV ≲ TRH ≲ 5 GeV. Our setup predicts a contribution to ∆Neff. that decreases for larger DM masses and is below the sensitivity of upcoming precision measurements such as CMB-S4. A future observation of a signal with ∆Neff. ≳ 0.012 would exclude our scenario. We further sketch how inflation, reheating and Affleck-Dine baryogenesis can also be potentially realized in this unified framework.

Baryon asymmetric Universe from spontaneous CP violation

Spontaneous CP violation, such as the Nelson-Barr (NB) mechanism, is an attractive scenario for addressing the strong CP problem while realizing the observed phase of the Cabibbo-Kobayashi-Maskawa (CKM) quark-mixing matrix. However, not only the CKM phase but also the baryon asymmetric Universe requires sources of CP violation. In this study, we show that a supersymmetric NB mechanism can naturally accommodate the Affleck-Dine (AD) baryogenesis within a CP-invariant Lagrangian. The model provides flat directions associated with new heavy quarks. Focusing on one of the directions, we find that the correct baryon asymmetry is obtained with a sufficiently low reheating temperature which does not cause the gravitino problem. Some parameter space is consistent with the gravitino dark matter. We assess radiative corrections to the strong CP phase induced by gauge-mediated supersymmetry breaking and CP-violating heavy fields and show that the strong CP problem is solved in a viable parameter space where the visible sector supersymmetric particles must be lighter than mathcal{O} (100) TeV. Even in the case that they are heavier than the TeV scale, our model predicts the neutron electric dipole moment within the reach of the near future experiments. Our model addresses the electroweak naturalness problem, strong CP problem, baryon asymmetric Universe, and dark matter. Then, the model may give a new compelling paradigm of physics beyond the Standard Model.

Detectable Gravitational Wave Signals from Affleck-Dine Baryogenesis.

In Affleck-Dine baryogenesis, the observed baryon asymmetry of the Universe is generated through the evolution of the vacuum expectation value of a scalar condensate. This scalar condensate generically fragments into nontopological solitons (Q balls). If they are sufficiently long-lived, they lead to an early matter domination epoch, which enhances the primordial gravitational wave signal for modes that enter the horizon during this epoch. The sudden decay of the Q balls results in a rapid transition from matter to radiation domination, producing a sharp peak in the gravitational wave power spectrum. Avoiding the gravitino over-abundance problem favors scenarios where the peak frequency of the resonance is within the range of the Einstein telescope and/or DECIGO. This observable signal provides a mechanism to test Affleck-Dine baryogenesis.

Strong clustering of primordial black holes from Affleck-Dine mechanism

Primordial black hole (PBH) is a fascinating candidate for the origin of binary merger events observed by LIGO-Virgo collaboration.The spatial distribution of PBHs at formation is an important feature to estimate the merger rate.We investigate the clustering of PBHs formed by Affleck-Dine (AD) baryogenesis, where dense baryon bubbles collapse to form PBHs.We found that formed PBHs show a strong clustering due to the stochastic dynamics of the AD field.Including the clustering, we evaluate the merger rate and isocurvature perturbations of PBHs, which show significant deviations from those without clustering.

Affleck-Dine baryogenesis with observable neutron-antineutron oscillation

We discuss the implications of Affleck-Dine (AD) baryogenesis for different classes of baryon and lepton number violating processes: specially focussing on implications for neutron-anti-neutron ($n-\bar{n}$) oscillation. The class of AD baryogenesis scenarios we work with uses the AD field also as the inflaton which is nonminimally coupled to gravity. We find that adequate baryogenesis and no washout by the baryon number ($B$) or the lepton number ($L$) violating operators implies constraints on the observability of the process or in the case of neutrino mass with compatibility with neutrino oscillation observations. In particular, for $n-\bar{n}$ oscillation, we study some of the familiar operators that connect the AD field to $n-\bar{n}$ oscillation and find that a split scalar spectrum model turns out to be most advantageous for obtaining an observable $n-\bar{n}$ while remaining consistent with AD baryogenesis. It is interesting that this spectrum is similar to a non-supersymmetyric SO(10) model for observable $n-\bar{n}$ oscillation discussed before, suggesting that this AD scenario can be embedded into a grand unified SO(10) model. We also find that for a low scale (all scales in the 100 TeV range), there is a narrow range of parameters where the observable $n-\bar{n}$ oscillation is compatible with viable AD baryogenesis. A feature of this baryogenesis scenario for $n-\bar{n}$ oscillation is that it necessarily predicts processes with $\Delta B=4$ or higher, all be it with highly suppressed amplitudes.

Minimal approach to baryogenesis via the Affleck-Dine mechanism and inflaton mass terms

We present a minimal approach to the generation of the baryon ($B$) asymmetry of the Universe, in which the asymmetry is generated in a complex inflaton condensate via $B$-violating quadratic inflaton potential terms using the Affleck-Dine (AD) mechanism. We show that the $B$-violating quadratic mass terms create an oscillating asymmetry in the complex inflaton condensate at late times. The final asymmetry transferred to the Standard Model sector at reheating is naturally reduced to the magnitude of the observed $B$ asymmetry by the effect of averaging over the $B$ oscillations. This approach to baryogenesis can easily be realised in a wide range of inflation models. We also show that AD baryogenesis via inflaton mass terms is free of the tuning of field dynamics required by the conventional AD mechanism.

Inflaton as the Affleck-Dine baryogenesis field in hilltop supernatural inflation

In this paper, we investigate the parameter space in the framework of hilltop supernatural inflation in which the inflaton field can play the role of Affleck-Dine field to produce successful baryogenesis. The suitable value of reheating temperature could coincide with the reheating temperature required to produce lightest supersymmetric particle dark matter. The baryon isocurvature perturbation is shown to be negligible. We consider $p=3$, $p=4$, and $p=6$ type III hilltop inflation and discuss how to connect the models to supersymmetric theories.

Q-ball decay through A-term in the gauge-mediated SUSY breaking scenario

Q-balls are non-topological solitons whose classical stability is ensured by a global U(1) charge. In particular, Q-balls are produced in the framework of the Affleck-Dine baryogenesis where U(1) charge is the baryon number. Since some type of Q-balls is stable against quantum decay into nucleons, it can work as the dark matter. When the dark matter Q-balls are captured into the neutron star, they absorb the surrounding neutrons and grow to consume all the neutrons, which leads to a stringent constraint on the Q-ball dark matter. However, the Q-ball growth stops due to the U(1) breaking A-term. We revisit the constraint by the neutron star for the gauge-mediation type and the new type Q-ball, and find the allowed parameter space, in which Q-balls work as the dark matter.

Baryogenesis via gravitational spontaneous symmetry breaking

We study baryogenesis in effective field theories where a $\mathrm{U}(1)_{ B-L}$-charged scalar couples to gravity via curvature invariants. We analyze the general possibilities in such models, noting the relationships between some of them and existing models, such as Affleck-Dine baryogenesis. We then identify a novel mechanism in which $\mathrm{U}(1)_{ B-L}$ can be broken by couplings to the Gauss-Bonnet invariant during inflation and reheating. Using analytic methods, we demonstrate that this mechanism provides a new way to dynamically generate the net matter-anti-matter asymmetry observed today, and verify this numerically.

Quintessential Affleck–Dine baryogenesis with non-minimal couplings

We present a novel Affleck–Dine scenario for the generation of the observed baryon asymmetry of the Universe based on the non-trivial interplay between quintessential inflationary models containing a kinetic dominated post-inflationary era and a non-minimally coupled U(1) field with a weakly broken B−L symmetry. The non-minimal coupling to gravity renders heavy the Affleck–Dine field during inflation and avoids the generation of isocurvature fluctuations. During the subsequent kinetic era the Ricci scalar changes sign and the effective mass term of the Affleck–Dine field becomes tachyonic. This allows the field to dynamically acquire a large expectation value. The symmetry of the Affleck–Dine potential is automatically restored at the onset of radiation domination, when the Ricci scalar approximately equals zero. This inverse phase transition results in the coherent oscillation of the scalar field around the origin of its effective potential. The rotation of the displaced Affleck–Dine field in the complex plane generates a non-zero B−L asymmetry which can be eventually converted into a baryon asymmetry via the usual transfer mechanisms.

Axion inflation and Affleck-Dine baryogenesis

String theory generically predicts the coupling between the Affleck-Dine field and axion field through higher-dimensional operators. We thus explore the Affleck-Dine baryogenesis on an axion background. It turns out that the axion oscillation produces an enough amount of baryon asymmetry of the Universe just after the inflation, even without a soft supersymmetry-breaking A-term. This baryogenesis scenario is applicable to the string axion inflation.

Superheavy thermal dark matter and primordial asymmetries

The early universe could feature multiple reheating events, leading to jumps in the visible sector entropy density that dilute both particle asymmetries and the number density of frozen-out states. In fact, late time entropy jumps are usually required in models of Affleck-Dine baryogenesis, which typically produces an initial particle-antiparticle asymmetry that is much too large. An important consequence of late time dilution, is that a smaller dark matter annihilation cross section is needed to obtain the observed dark matter relic density. For cosmologies with high scale baryogenesis, followed by radiation-dominated dark matter freeze-out, we show that the perturbative unitarity mass bound on thermal relic dark matter is relaxed to 1010 GeV. We proceed to study superheavy asym-metric dark matter models, made possible by a sizable entropy injection after dark matter freeze-out, and identify how the Affleck-Dine mechanism would generate the baryon and dark asymmetries.

Affleck-Dine baryogenesis in type IIB string models

We present a viable string embedding of Affleck-Dine baryogenesis in type IIB sequestered models where the late-time decay of the lightest modulus reheats the universe to relatively low temperatures. We show that if inflation is driven by a blow-up Kaehler modulus, the Affleck-Dine field can become tachyonic during inflation if the Kaehler metric for matter fields has an appropriate inflaton-dependent contribution. We find that the Affleck-Dine mechanism can generate the observed baryon asymmetry for natural values of the underlying parameters which lead also to successful inflation and low-energy gaugino masses in a split supersymmetry scenario. The reheating temperature from the lightest modulus decay is high enough to allow thermal Higgsino-like dark matter.

Affleck-Dine baryogenesis just after inflation

We propose a new scenario of Affleck-Dine baryogenesis where a flat direction in the MSSM generates B-L asymmetry just after the end of inflation. The resulting amount of baryon asymmetry is independent of low-energy supersymmetric models but is dependent on inflation models. We consider the hybrid and chaotic inflation models and find that reheating temperature is required to be higher than that in the conventional scenario of Affleck-Dine baryogenesis. In particular, non-thermal gravitino-overproduction problem is naturally avoided in the hybrid inflation model. Our results imply that Affleck-Dine baryogenesis can be realized in a broader range of supersymmetry and inflation models than expected in the literature.

Thermalization process after inflation and effective potential of scalar field

We investigate the thermalization process of the Universe after inflation to determine the evolution of the effective temperature. The time scale of thermalization is found to be so long that it delays the evolution of the effective temperature, and the resulting maximal temperature of the Universe can be significantly lower than the one obtained in the literature. Our results clarify the finite density corrections to the effective potential of a scalar field and also processes of heavy particle production. In particular, we find that the maximum temperature of the Universe may be at most electroweak scale if the reheating temperature is as low as \U0001d4aa (1) MeV, which implies that the electroweak symmetry may be marginally restored. In addition, it is noticeable that the dark matter may not be produced from thermal plasma in such a low reheating scenario, since the maximum temperature can be smaller than the conventional estimation by five orders of magnitude. We also give implications to the Peccei-Quinn mechanism and the Affleck-Dine baryogenesis.

Early universe cosmology, effective supergravity, and invariants of algebraic forms

The presence of light scalars can have profound effects on early universe cosmology, influencing its thermal history as well as paradigms like inflation and baryogenesis. Effective supergravity provides a framework to make quantifiable, model-independent studies of these effects. The Riemanian curvature of the Kahler manifold spanned by scalars belonging to chiral superfields, evaluated along supersymmetry breaking directions, provides an order parameter (in the sense that it must necessarily take certain values) for phenomena as diverse as slow roll modular inflation, non-thermal cosmological histories, and the viability of Affleck-Dine baryogenesis. Within certain classes of UV completions, the order parameter for theories with $n$ scalar moduli is conjectured to be related to invariants of $n$-ary cubic forms (for example, for models with three moduli, the order parameter is given by the ring of invariants spanned by the Aronhold invariants). Within these completions, and under the caveats spelled out, this may provide an avenue to obtain necessary conditions for the above phenomena that are in principle calculable given nothing but the intersection numbers of a Calabi-Yau compactification geometry. As an additional result, abstract relations between holomorphic sectional and bisectional curvatures are utilized to constrain Affleck-Dine baryogenesis on a wide class of Kahler geometries.

ChargedQ-balls in gauge mediated SUSY breaking models

It is known that after Affleck-Dine baryogenesis, spatial inhomogeneities of Affleck-Dine field grow into non-topological solitons called Q-balls. In gauge mediated SUSY breaking models, sufficiently large Q-balls with baryon charge are stable while Q-balls with lepton charge can always decay into leptons. For a Q-ball that carries nonzero $B$ and $L$ charges, the difference between the baryonic component and the leptonic component in decay rate may induce nonzero electric charge on the Q-ball. This implies that charged Q-ball, also called gauged Q-ball, may emerge in our universe. In this paper, we investigate two complex scalar fields, a baryonic scalar field and a leptonic one, in an Abelian gauge theory. We find stable solutions of gauged Q-balls for different baryon and lepton charges. Those solutions shows that a Coulomb potential arises and the Q-ball becomes electrically charged as expected. It is energetically favored that some amount of leptonic component decays, but there is an upper bound on its amount due to the Coulomb force. The baryonic decay also becomes possible by virtue of electrical repulsion and we find the condition to suppress it so that the charged Q-balls can survive in the universe.