1,687 research outputs found
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.Comment: 6 page
Q-ball formation: Obstacle to Affleck-Dine baryogenesis in the gauge-mediated SUSY breaking ?
We consider the Affleck-Dine baryogenesis comprehensively in the minimal
supersymmetric standard model with gauge-mediated supersymmetry breaking.
Considering the high temperature effects, we see that the Affleck-Dine field is
naturally deformed into the form of the Q ball. In the natural scenario where
the initial amplitude of the field and the A-terms are both determined by the
nonrenormalizable superpotential, we obtain only very a narrow allowed region
in the parameter space in order to explain the baryon number of the universe
for the case that the Q-ball formation occurs just after baryon number
production. Moreover, most of the parameter sets suited have already been
excluded by current experiments. We also find new situations in which the
Q-ball formation takes place rather late compared with baryon number creation.
This situation is more preferable, since it allows a wider parameter region for
naturally consistent scenarios, although it is still difficult to realize in
the actual cosmological scenario.Comment: 27 pages, RevTeX, 21 postscript figures included. The version to be
publishe
Affleck-Dine mechanism with negative thermal logarithmic potential
We investigate whether the Affleck-Dine (AD) mechanism works when the
contribution of the two-loop thermal correction to the potential is negative in
the gauge-mediated supersymmetry breaking models. The AD field is trapped far
away from the origin by the negative thermal correction for a long time until
the temperature of the universe becomes low enough. The most striking feature
is that the Hubble parameter becomes much smaller than the mass scale of the
radial component of the AD field, during the trap. Then, the amplitude of the
AD field decreases so slowly that the baryon number is not fixed even after the
onset of radial oscillation. The resultant baryon asymmetry crucially depends
on whether the Hubble parameter, , is larger than the mass scale of the
phase component of the AD field, , at the beginning of oscillation.
If holds, the formation of Q balls plays an essential role to
determine the baryon number, which is found to be washed out due to the
nonlinear dynamics of Q-ball formation. On the other hand, if
holds, it is found that the dynamics of Q-ball formation does not affect the
baryon asymmetry, and that it is possible to generate the right amount of the
baryon asymmetry.Comment: 18 pages, RevTeX4, 9 postscript figures included, final version to
appear in Phys.Rev.
Early reionization by decaying particles and cosmic microwave background radiation
We study the reionization scenario in which ionizing UV photons emitted from
decaying particle, in addition to usual contributions from stars and quasars,
ionize the universe. It is found that the scenario is consistent with both the
first year data of the Wilkinson Microwave Anisotropy Probe and the fact that
the universe is not fully ionized until z \sim 6 as observed by Sloan Digital
Sky Survey. Likelihood analysis revealed that rather broad parameter space can
be chosen. This scenario will be discriminated by future observations,
especially by the EE polarization power spectrum of cosmic microwave background
radiation.Comment: 5 pages, 5 figures, fig 2, table 1, and some typos are correcte
Q-ball formation in the wake of Hubble-induced radiative corrections
We discuss some interesting aspects of the -ball formation during the
early oscillations of the flat directions. These oscillations are triggered by
the running of soft stemming from the nonzero energy density
of the Universe. However, this is quite different from the standard -ball formation. The running in presence of gauge and Yukawa couplings
becomes strong if is sufficiently large. Moreover, the -balls which are formed during the early oscillations constantly evolve, due
to the redshift of the Hubble-induced soft mass, until the low-energy
supersymmtery breaking becomes dominant. For smaller , -balls are not formed during early oscillations because of the shrinking of
the instability band due to the Hubble expansion. In this case the -balls are formed only at the weak scale, but typically carry smaller
charges, as a result of their amplitude redshift. Therefore, the Hubble-induced
corrections to the flat directions give rise to a successful -ball
cosmology.Comment: 7 revtex pages, few references corrected and added, final version to
appear in Phys. Rev.
Impact of dark matter decays and annihilations on reionization
One of the possible methods to distinguish among various dark matter
candidates is to study the effects of dark matter decays. We consider four
different dark matter candidates (light dark matter, gravitinos, neutralinos
and sterile neutrinos), for each of them deriving the decaying/annihilation
rate, the influence on reionization, matter temperature and CMB spectra. We
find that light dark matter particles (1-10 MeV) and sterile neutrinos (2-8
keV) can be sources of partial early reionization (z<~100). However, their
integrated contribution to Thomson optical depth is small (<~0.01) with respect
to the three year WMAP results (tau_e=0.09+/-0.03). Finally, they can
significantly affect the behavior of matter temperature. On the contrary,
effects of heavy dark matter candidates (gravitinos and neutralinos) on
reionization and heating are minimal. All the considered dark matter particles
have completely negligible effects on the CMB spectra.Comment: 6 pages, 5 figures; MNRAS, in pres
On the Moduli Problem and Baryogenesis in Gauge-mediated SUSY Breaking Models
We investigate whether the Affleck-Dine mechanism can produce sufficient
baryon number of the universe in the gauge-mediated SUSY breaking models, while
evading the cosmological moduli problem by late-time entropy production. We
find that the Q-ball formation renders the scenario very difficult to work,
irrespective of the detail mechanism of the entropy production.Comment: 11 pages, RevTeX, 5 postscript figures include
Money Matters: An Educational Intervention to Improve Financial Wellness and Literacy Among Medical Students
Objective or purpose of innovation: We created a curriculum for medical students that targets gaps in personal finance and assessed self-perception of financial wellness and literacy.
Background and/or theoretical framework and importance to the field: Financial stressors associated with student loan debt and poor financial literacy leads to burnout among medical students and professionals. Providing earlier financial training may inform proactive planning and improve overall wellness.
Design: First-year medical students participated in an education activity covering topics such as personal finance, budgeting, student loans, and loan repayment programs. Participants reviewed informational handouts and watched pre-recorded videos followed by a faculty-led debrief in small groups. A 12-question survey was delivered to participants after the activity to retrospectively evaluate self-perception of financial literacy before and after the curricular intervention (retrospective pre-post approach). Likert-scale items (1:4, strongly disagree: strongly agree) were used. Pre- and post-activity mean scores were compared using paired t-tests.
Outcomes: Out of the 77 participants, 69 (90%) completed the survey. Overall, participants felt more confident in their personal financial knowledge (2.38 vs 3.06, p<.001), and 98% of participants agreed that this activity motivated them to learn more about financial literacy. For debt management, participants felt more confident in building a strategy to manage financial debt (2.77 vs 3.33, p<0.001), cultivated a better understanding of loan terms (2.49 vs 3.57, p<0.001), and became more aware of loan repayment options (2.43 vs 3.51, p<0.001). All participants agreed that this activity should be continued for future medical students (27% somewhat agree, 73% strongly agree).
Innovationâs strengths and limitations: Financial literacy education is associated with improved understanding, confidence, and appreciation of personal finance among medical students and should be considered for inclusion in other medical education programs.
Feasibility and generalizability: A short instructional video combined with group discussion can be an effective model for addressing this sometimes under-appreciated aspect of student wellness
Numerical simulations of fragmentation of the Affleck-Dine condensate
We present numerical simulations of fragmentation of the Affleck-Dine
condensate in two spatial dimensions. We argue analytically that the final
state should consist of both Q-balls and anti-Q-balls in a state of maximum
entropy, with most of the balls small and relativistic. Such a behaviour is
found in simulations on a 100x100 lattice with cosmologically realistic
parameter values. During fragmentation process, we observe filament-like
texture in the spatial distribution of charge. The total charge in Q-balls is
found to be almost equal to the charge in anti-Q-balls and typically orders of
magnitude larger than charge asymmetry. Analytical considerations indicate
that, apart from geometrical factors, the results of the simulated two
dimensional case should apply also to the fully realistic three dimensional
case.Comment: 28 pages, 39 figure
Reheating as a surface effect
We describe a new mechanism for reheating the Universe through evaporation of
a surface charge of a fragmented inflaton condensate. We show that for a range
of Yukawa coupling of the inflaton to the matter sector evaporation gives rise
to a much smaller reheat temperature compared to the standard perturbative
decay. As a consequence, reheating through a surface effect could solve the
gravitino and moduli over production problem in inflationary models without
fine tuning the Yukawa sector.Comment: 4 page
- âŠ