Affleck-Dine Field Research Articles

Revisiting Affleck-Dine leptogenesis with light sleptons

We revisit the Affleck-Dine leptogenesis via the L H_u flat direction with a light slepton field. Although the light slepton field is favored in low-energy SUSY phenomenologies, such as the muon g - 2 anomaly and bino-slepton coannihilation, it may cause a problem in the Affleck-Dine leptogenesis: it may create an unwanted charge-breaking vacuum in the Affleck-Dine field potential so that the Affleck-Dine field is trapped during the course of leptogenesis. We investigate the conditions under which such an unwanted vacuum exists and clarify that both thermal and quantum corrections are important for the (temporal) disappearance of the charge-breaking minimum. We also confirm that if the charge-breaking vacuum disappears due to the thermal or quantum correction, the correct baryon asymmetry can be produced while avoiding the cosmological gravitino problem.

Charge transfer between rotating complex scalar fields

We consider the transfer of a U(1) charge density between Bose-Einstein condensates of complex scalar fields coupled to a thermal bath, focusing on the case of a homogeneous Affleck-Dine field transmitting the charge stored in its angular motion to an axion field. We demonstrate that in the absence of additional symmetries this charge transfer, aided by cosmic expansion as well as the thermal effective potential of the Affleck-Dine field, can be very efficient. The charge redistribution between the scalar fields becomes possible if the interactions with the thermal bath break the original U(1) × U(1) symmetry down to a single U(1) symmetry; the charge distribution between the two fields is then determined by minimizing the free energy. We discuss implications for cosmological setups involving complex scalars, with applications to axion dark matter, baryogenesis, kination domination, and gravitational wave production.

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.

Magnetogenesis from a rotating scalar: \xe0 la scalar chiral magnetic effect

The chiral magnetic effect (CME) is a phenomenon in which an electric current is induced parallel to an external magnetic field in the presence of chiral asymmetry in a fermionic system. In this paper, we show that the electric current induced by the dynamics of a pseudo-scalar field which anomalously couples to electromagnetic fields can be interpreted as closely analogous to the CME. In particular, the velocity of the pseudo-scalar field, which is the phase of a complex scalar, indicates that the system carries a global U(1) number asymmetry as the source of the induced current. We demonstrate that an initial kick to the phase-field velocity and an anomalous coupling between the phase-field and gauge fields are naturally provided, in a set-up such as the Affleck-Dine mechanism. The resulting asymmetry carried by the Affleck-Dine field can give rise to instability in the (electro)magnetic field. Cosmological consequences of this mechanism are also investigated.

More about Q-ball with elliptical orbit

Q-balls formed from the Affleck-Dine field have rich cosmological implications and have been extensively studied from both theoretical and simulational approaches. From the theoretical point of view, the exact solution of the Q-ball was obtained and it shows a circular orbit in the complex plane of the field value. In practice, however, it is reported that the Q-ball that appears after the Affleck-Dine mechanism has an elliptical orbit, which carries larger energy per unit U(1) charge than the well-known solution with a circular orbit. We call them “elliptical” Q-balls. In this paper, we report the first detailed investigation of the properties of the elliptical Q-balls by 3D lattice simulation. The simulation results indicate that the elliptical Q-ball has an almost spherical spatial profile with no nodes, and we observed a highly elliptic orbit that cannot be described through small perturbations around the ground state Q-ball. Higher ellipticity leads to more excitation of the energy, whose relation is also derived as a dispersion relation. Finally, we derive two types of approximate solutions by extending the Gaussian approximation and considering the time-averaged equation of motion and we also show the consistency with the simulation results.

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.

Oscillating Affleck-Dine condensate and its cosmological implications

We study the dynamics of the Affleck-Dine field after inflation in more detail. After inflation, the Affleck-Dine field inevitably oscillates around the potential minimum. This oscillation is hard to decay and can cause accidental suppression of the consequential baryon asymmetry. This suppression is most effective for the model with non-renormalizable superpotential $W_{AD}\sim \Phi^4$ ($\Phi$: Affleck-Dine field). It is found that the Affleck-Dine leptogenesis in high-scale inflation, which suffers from serious gravitino overproduction, becomes workable owing to this effect.

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.

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.

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.

Q-ball dark matter and baryogenesis in high-scale inflation

We investigate the scenario that one flat direction creates baryon asymmetry of the universe, while Q balls from another direction can be the dark matter in the gauge-mediated supersymmetry breaking for high-scale inflation. Isocurvature fluctuations are suppressed by the fact that the Affleck–Dine field stays at around the Planck scale during inflation. We find that the dark matter Q balls can be detected in IceCube-like experiments in the future.

Towards constraining Affleck-Dine baryogenesis

Affleck-Dine baryogenesis is preconditioned on a certain structure of non-renormalizable operators in the Kahler potential. In this paper, we geometrically characterize the resulting constraint on the field space Kahler geometry and survey the Lagrangian for correlated predictions. The Affleck-Dine field backreacts on the inflaton, and by mapping the backreacted potential to an inflaton potential with a step, we find that current CMB data severely constrain some versions of the scenario.

Formation of theQball in the thermal logarithmic potential and its properties

We investigate the $Q$-ball formation in the thermal logarithmic potential by means of the lattice simulation, and reconfirm qualitatively the relation between $Q$-ball charge and the amplitude of the Affleck-Dine field at the onset of its oscillation. We find time dependence of some properties of the $Q$ ball, such as its size and the field value at its center. Since the thermal logarithmic potential decreases as the temperature falls down, the gravity-mediation potential will affect the properties of the $Q$ ball. Even in the case when the gravity-mediation potential alone does not allow $Q$-ball solution, we find the transformation from the thick-wall type of the $Q$ ball to the thin-wall type, contrary to the naive expectation that the $Q$ balls will be destroyed immediately when the gravity-mediation potential becomes dominant at the center of the $Q$ ball.

Towards the robustness of the Affleck–Dine mechanism

In this talk we considered the Affleck–Dine mechanism with various types of the Kähler potential, and investigated whether or not the Affleck–Dine field could acquire a large VEV as an initial condition for successful baryogenesis. In addition to a negative Hubble-induced mass term, we found examples that large enough Hubble-induced A-terms could also develop the minima at a large amplitude of the field. It is concluded, therefore, that the Affleck–Dine mechanism works for broader classes of the theories. This talk is based on Kasuya and Kawasaki (2006 Phys. Rev. D 74 063507). Here I extend the discussion from a more generic standpoint, and find that essentially there are three cases that large enough A-terms develop minima at large field values.

Preheating and Affleck–Dine leptogenesis after thermal inflation

Previously, we proposed a model of low energy Affleck–Dine leptogenesis in the contextof thermal inflation. The lepton asymmetry is generated at the end of thermalinflation, which occurs at a relatively low energy scale with the Hubble parametersomewhere in the range . Thus Hubble damping will be ineffective in bringing the Affleck–Dine field into the leptonconserving region near the origin, leaving the possibility that the lepton number could bewashed out. Previously, we suggested that preheating could damp the amplitude of theAffleck–Dine field allowing conservation of the lepton number. In this paper, wedemonstrate numerically that preheating does efficiently damp the amplitude of theAffleck–Dine field and that the lepton number is conserved as the result. In addition todemonstrating a crucial aspect of our model, it also opens the more general possibility oflow energy Affleck–Dine baryogenesis.

Affleck–Dine baryogenesis in anomaly-mediated supersymmetry breaking

It is known that in the anomaly-mediated supersymmetry breaking model, Affleck–Dinebaryogenesis does not work due to trapping of the Affleck–Dine field into charge breakingminima. We show that when the finite-temperature effect is properly taken into account and ifthe reheating temperature is relatively high, the problem of falling into charge breaking globalminima can be avoided and hence Affleck–Dine baryogenesis works. Moreover, for theLHu flat direction we obtain a constraint on the mass of the neutrino.

Towards the robustness of the Affleck-Dine baryogenesis

We study the Affleck-Dine mechanism with various types of the Kahler potential, and investigate whether or not the Affleck-Dine field could acquire a large VEV as an initial condition for successful baryogenesis. In addition to a negative Hubble-induced mass term, we find that large enough Hubble-induced A-terms could also develop the minimum at large amplitude of the field. Therefore, the Affleck-Dine mechanism works for broader classes of the theories.

Fate of oscillating scalar fields in a thermal bath and their cosmological implications

Relaxation process of a coherent scalar field oscillation in the thermal bath is investigated using nonequilibrium quantum field theory. The Langevin-type equation of motion is obtained which has a memory term and both additive and multiplicative noise terms. The dissipation rate of the oscillating scalar field is calculated for various interactions such as Yukawa coupling, three-body scalar interaction, and biquadratic interaction. When the background temperature is larger than the oscillation frequency, the dissipation rate arising from the interactions with fermions is suppressed due to the Pauli-blocking, while it is enhanced for interactions with bosons due to the induced effect. In both cases, we find that the microphysical detailed-balance relation drives the oscillating field to a thermal equilibrium state. That is, for low-momentum modes, the classical fluctuation-dissipation theorem holds and they relax to a state the equipartition law is satisfied, while higher-momentum modes reach the state the number density of each quanta consists of the thermal boson distribution function and zero-point vacuum contribution. The temperature-dependent dissipation rates obtained here are applied to the late reheating phase of inflationary universe. It is found that in some cases the reheat temperature may take a somewhat different value from the conventional estimates, and in an extreme case the inflaton can dissipate its energy without linear interactions that leads to its decay. Furthermore the evaporation rate of the Affleck-Dine field at the onset of its oscillation is calculated.

Curvaton scenario with Affleck-Dine baryogenesis

We discuss the curvaton scenario with the Affleck-Dine baryogenesis. In this scenario, non-vanishing baryonic entropy fluctuation may be generated even without primordial fluctuation of the Affleck-Dine field. Too large entropy fluctuation is inconsistent with the observations and hence constraints on the curvaton scenario with the Affleck-Dine baryogenesis are obtained. We calculate the baryonic entropy fluctuation (as well as other cosmological density fluctuations) in this case and derive constraints. Implications to some of the models of the curvaton are also discussed.

Curvatons in supersymmetric models

We study the curvaton scenario in supersymmetric framework paying particular attention to the fact that scalar fields are inevitably complex in supersymmetric theories. If there are more than one scalar fields associated with the curvaton mechanism, isocurvature (entropy) fluctuations between those fields in general arise, which may significantly affect the properties of the cosmic density fluctuations. We examine several candidates for the curvaton in the supersymmetric framework, such as moduli fields, Affleck-Dine field, $F$- and $D$-flat directions, and right-handed sneutrino. We estimate how the isocurvature fluctuations generated in each case affect the cosmic microwave background angular power spectrum. With the use of the recent observational result of the WMAP, stringent constraints on the models are derived and, in particular, it is seen that large fraction of the parameter space is excluded if the Affleck-Dine field plays the role of the curvaton field. Natural and well-motivated candidates of the curvaton are also listed.