124 research outputs found
Unstable Semiclassical Trajectories in Tunneling
Some tunneling phenomena are described, in the semiclassical approximation,
by unstable complex trajectories. We develop a systematic procedure to
stabilize the trajectories and to calculate the tunneling probability,
including both the suppression exponent and prefactor. We find that the
instability of tunneling solutions modifies the power-law dependence of the
prefactor on h as compared to the case of stable solutions.Comment: Journal version; 4 pages, 2 figure
Theta--instantons in SU(2) Higgs theory
We consider topology changing processes in SU(2)--Higgs theory. In the
Standard Model of particle physics they are accompanied by baryon--and
lepton--number non--conservation. At fixed energy and multiplicity of initial
state, these processes are described by classical Theta--instanton solutions.
We describe these solutions and calculate the suppression exponents for the
probabilities of the topology changing transitions at relatively low energies.Comment: 12 pages, 5 figure
Analytic description of monodromy oscillons
We develop precise analytic description of oscillons - long-lived
quasiperiodic field lumps - in scalar field theories with nearly quadratic
potentials, e.g. the monodromy potential. Such oscillons are essentially
nonperturbative due to large amplitudes, and they achieve extreme longevities.
Our method is based on a consistent expansion in the anharmonicity of the
potential at strong fields, which is made accurate by introducing a
field-dependent "running mass." At every order, we compute effective action for
the oscillon profile and other parameters. Comparison with explicit numerical
simulations in (3+1)-dimensional monodromy model shows that our method is
significantly more precise than other analytic approaches.Comment: 9 pages, 9 figures; v2: Introduction, Sec. 4 and Discussion extended;
journal versio
Numerical study of multiparticle production in theory
We study multiparticle production in the unbroken -dimensional
theory using the semiclassical method of singular solutions. We
show that the probabilities of these processes are exponentially suppressed in
terms of a small coupling constant if the multiplicity of the
final state is large: . At the probabilities
agree with well-known perturbative results. At they are
dominated by loop effects and decrease exponentially with , as we show for
the first time.Comment: 7 pages, 2 figures. A contribution to International Conference on
Quantum Field Theory, High-Energy Physics, and Cosmology, 18-21 July 2022,
Dubna, Russian Federatio
Soliton-antisoliton pair production in particle collisions
We propose general semiclassical method for computing the probability of
soliton-antisoliton pair production in particle collisions. The method is
illustrated by explicit numerical calculations in (1+1)-dimensional scalar
field model. We find that the probability of the process is suppressed by an
exponentially small factor which is almost constant at high energies.Comment: 4 pages, 3 figures, journal versio
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