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Alexander Kusenko

Publications and source records attributed to Alexander Kusenko.

At least 199 records · Page 11Linked to original sources
arXiv1997

New physics in a nutshell, or Q-ball as a power plant

Future experiments may discover new scalar particles with global charges and couplings that allow for solitonic states. If the effective potential has flat directions, the scalar VEV inside a large Q-ball can exceed the particle mass by many orders of magnitude. Models with low-energy supersymmetry breaking generically have both the scalars carrying some global charges, and the flat directions. The Q-ball interior can, therefore, provide an environment for exploring physics far beyond the TeV scale without the need for building colliders of ever-increasing energies. Some Standard Model processes, otherwise strongly suppressed, can also be studied inside the soliton, where the SU(2) symmetry can be restored, and the quark confinement may be absent. Baryon number violating processes catalyzed by the large VEV inside the Q-ball can provide an inexhaustible energy resource.

hep-ph↗
arXiv1997

Reply to Comment on "Pulsar velocities and neutrino oscillations"

We have recently proposed an explanation for the birth velocities of pulsars based on neutrino oscillations (hep-ph/9606428). One of the quantities, dN/dT, was evaluated in the approximation of constant chemical potential for the electrons. An alternative approximation based on the assumption Ye=const, used by Qian (astro-ph/9705055), yields a somewhat higher prediction for the magnetic field inside a neutron star. If the same input parameters are used, the two approximations are in reasonable agreement, given the uncertainty in the geometry of the magnetic field and the simplified picture of neutrino emission that comes with the notion of a neutrinosphere.

hep-ph↗
arXiv1997

Q-balls in the MSSM

Q-balls are generically present in models with softly broken low-energy supersymmetry. We discuss the properties of these non-topological solitons, which can precipitate a new kind of first-order phase transition in the early Universe and have other important implications for cosmology and experiment.

hep-ph↗
arXiv1997

Phase transitions precipitated by solitosynthesis

Solitosynthesis of Q-balls in the false vacuum can result in a phase transition of a new kind. Formation and subsequent growth of Q-balls via the charge accretion proceeds until the solitons reach a critical charge, at which point it becomes energetically favorable for the Q-ball interior to expand filling space with the true vacuum phase. Solitosynthesis can destabilize a false vacuum even when the tunneling rate is negligible. In models with low-energy supersymmetry, where the Q-balls associated with baryon and lepton number conservation are generically present, solitosynthesis can precipitate transitions between the vacua with different VEV's of squarks and sleptons.

hep-ph↗
arXiv1997

Solitons in the supersymmetric extensions of the Standard Model

All supersymmetric generalizations of the Standard Model allow for stable non-topological solitons of the Q-ball type which may have non-zero baryon and lepton numbers, as well as the electric charge. These solitons can be produced in the early Universe, can affect the nucleosynthesis, and can lead to a variety of other cosmological consequences.

hep-ph↗
arXiv1997

Small Q balls

We develop an adequate description of non-topological solitons with a small charge, for which the thin-wall approximation is not valid. There is no classical lower limit on the charge of a stable Q-ball. We examine the parameters of these small-charge solitons and discuss the limits of applicability of the semiclassical approximation.

hep-th↗
arXiv1997

Neutral current induced neutrino oscillations in a supernova

Neutral currents induced matter oscillations of electroweak-active (anti-)neutrinos to sterile neutrinos can explain the observed motion of pulsars. In contrast to a recently proposed explanation of the pulsar birth velocities based on the electron to tau (muon) neutrino oscillations [hep-ph/9606428], the heaviest neutrino (either active or sterile) would have to have mass of order several keV.

hep-ph↗
arXiv1996

Velocities of pulsars and neutrino oscillations

Neutrino oscillations, biased by the magnetic field, alter the shape of the neutrinosphere in a cooling protoneutron star emerging from the supernova collapse. The resulting anisotropy in the momentum of outgoing neutrinos can be the origin of the observed proper motions of pulsars. The connection between the pulsars velocities and neutrino oscillations results in a prediction for the tau neutrino mass of order 100 eV.

hep-ph↗
arXiv1996

Vacuum decay and internal symmetries

We study the effects of internal symmetries on the decay by bubble nucleation of a metastable false vacuum. The zero modes about the bounce solution that are associated with the breaking of continuous internal symmetries result in an enhancement of the tunneling rate into vacua in which some of the symmetries of the initial state are spontaneously broken. We develop a general formalism for evaluating the effects of these zero modes on the bubble nucleation rate in both flat and curved space-times.

hep-th↗
arXiv1996

The origin of pulsar velocities

We have recently proposed an explanation for the birth velocities of pulsars as resulting from asymmetries due to neutrino oscillations in the cooling protoneutron star. A specific prediction of this mechanism is that the correlation of velocities and magnetic fields should be stronger for slowly rotating neutron stars and weaker for those whose periods are less than 1 s. A remarkable agreement of this prediction with the data favors the oscillation mechanism over the alternative explanations for the proper motion of pulsars.

astro-ph↗
arXiv1996

Is the vacuum stable?

The experimental data, as well as theoretical considerations allow (and, in some cases, require) the Universe at present to rest in a false vacuum, whose approximate stability imposes constraints on the model parameters. Under very general and mild conditions, the Universe would have ended up in the standard vacuum even if the potential has deeper minima, provided there was a period in which the temperature was > 1 TeV. In many cases, the zero temperature tunneling rate is much smaller than the inverse age of the Universe. Future experiments may reveal that the physical vacuum is not entirely stable. Implications for the cosmological constant are discussed.

hep-ph↗
arXiv1996

Color and charge breaking minima in the MSSM

The scalar potential of theories with broken supersymmetry can have a number of local minima characterized by different gauge groups. Symmetry properties of the physical vacuum constrain the parameters of the MSSM. We discuss these constraints, in particular those that result from the vacuum stability with respect to quantum tunneling.

hep-ph↗
arXiv1996

Phase Transitions and Vacuum Tunneling Into Charge and Color Breaking Minima in the MSSM

The scalar potential of the MSSM may have local and global minima characterized by non-zero expectation values of charged and colored bosons. Even if the true vacuum is not color and charge conserving, the early Universe is likely to occupy the minimum of the potential in which only the neutral Higgs fields have non-zero vev's. The stability of this false vacuum with respect to quantum tunneling imposes important constraints on the values of the MSSM parameters. We analyze these constraints using some novel methods for calculating the false vacuum decay rate. Some regions of the MSSM parameter space are ruled out because the lifetime of the corresponding physically acceptable false vacuum is small in comparison to the present age of the Universe. However, there is a significant fraction of the parameter space that is consistent with the hypothesis that the Universe rests in the false vacuum that is stable on a cosmological time scale.

hep-ph↗
arXiv1995

Supersymmetry in the false vacuum

A metastable state, or a false vacuum, is not an eigenstate of the Hamiltonian in quantum field theory. Its energy density has a non-zero imaginary part equal to its decay width. Therefore, supersymmetry cannot be exact in the false vacuum. We calculate the size of this effect using the path integral approach.

hep-ph↗
arXiv1995

Tunneling in quantum field theory with spontaneous symmetry breaking

Tunneling in quantum field theory is well understood in the case of a single scalar field. However, in theories with spontaneous symmetry breaking, one has to take into account the additional zero modes which appear due to the Goldstone phenomenon. We calculate the false vacuum decay rate in this case. The result may differ significantly from the tunneling rates in the absence of symmetry breaking.

hep-ph↗
arXiv1993

A New Model for Fermion Masses in Supersymmetric Grand Unified Theories

We present a simple model for fermion mass matrices and quark mixing in the context of supersymmetric grand unified theories and show its agreement with experiment. Our model realizes the GUT mass relations $m_d=3m_e$, $m_s= m_μ/3$, $m_b=m_τ$ in a new way and is easily consistent with values of $m_t$ suggested by MSSM fits to LEP data.

hep-ph↗
arXiv1992

Invariants Describing Quark Mixing and Mass Matrices

We introduce two new sets of invariant functions of quark mass matrices, which express the constraints on these mass matrices due to knowledge of the quark mixing matrix. These invariants provide a very simple method to test candidate forms for mass matrices.

hep-ph↗