64 research outputs found
The Effect of Time Variation in the Higgs Vacuum Expectation Value on the Cosmic Microwave Background
A time variation in the Higgs vacuum expectation value alters the electron
mass and thereby changes the ionization history of the universe. This change
produces a measurable imprint on the pattern of cosmic microwave background
(CMB) fluctuations. The nuclear masses and nuclear binding energies, as well as
the Fermi coupling constant, are also altered, with negligible impact on the
CMB. We calculate the changes in the spectrum of the CMB fluctuations as a
function of the change in the electron mass. We find that future CMB
experiments could be sensitive to |\Delta m_e/m_e| \sim |\Delta G_F/G_F| \sim
10^{-2} - 10^{-3}. However, we also show that a change in the electron mass is
nearly, but not exactly, degenerate with a change in the fine-structure
constant. If both the electron mass and the fine-structure constant are
time-varying, the corresponding CMB limits are much weaker, particularly for l
< 1000.Comment: 6 pages, 3 figures, Fig. 3 modified, other minor correction
Gas-liquid transition in the model of particles interacting at high energy
An application of the ideas of the inertial confinement fusion process in the
case of particles interacting at high energy is investigated. A possibility of
the gas-liquid transition in the gas is considered using different approaches.
In particular, a shock wave description of interactions between particles is
studied and a self-similar solution of Euler's equation is discussed.
Additionally, Boltzmann equation is solved for self-consistent field (Vlasov's
equation) in linear approximation for the case of a gas under external pressure
and the corresponding change of Knudsen number of the system is calculated.Comment: 24 pages, 2 figur
Phase of the Wilson Line at High Temperature in the Standard Model
We compute the effective potential for the phase of the Wilson line at high
temperature in the standard model to one loop order. Besides the trivial vacua,
there are metastable states in the direction of hypercharge. Assuming
that the universe starts out in such a metastable state at the Planck scale, it
easily persists to the time of the electroweak phase transition, which then
proceeds by an unusual mechanism. All remnants of the metastable state
evaporate about the time of the phase transition.Comment: 4 pages in ReVTeX plus 1 figure; Columbia Univ. preprint CU-TP-63
Understanding the coevolution of mask wearing and epidemics:A network perspective
Nonpharmaceutical interventions (NPIs) such as mask wearing can be effective in mitigating the spread of infectious diseases. Therefore, understanding the behavioral dynamics of NPIs is critical for characterizing the dynamics of disease spread. Nevertheless, standard infection models tend to focus only on disease states, overlooking the dynamics of "beneficial contagions," e.g., compliance with NPIs. In this work, we investigate the concurrent spread of disease and mask-wearing behavior over multiplex networks. Our proposed framework captures both the competing and complementary relationships between the dueling contagion processes. Further, the model accounts for various behavioral mechanisms that influence mask wearing, such as peer pressure and fear of infection. Our results reveal that under the coupled disease-behavior dynamics, the attack rate of a disease-as a function of transition probability-exhibits a critical transition. Specifically, as the transmission probability exceeds a critical threshold, the attack rate decreases abruptly due to sustained mask-wearing responses. We empirically explore the causes of the critical transition and demonstrate the robustness of the observed phenomena. Our results highlight that without proper enforcement of NPIs, reductions in the disease transmission probability via other interventions may not be sufficient to reduce the final epidemic size.</p
Constraints on the Variation of the Fine Structure Constant from Big Bang Nucleosynthesis
We put bounds on the variation of the value of the fine structure constant
, at the time of Big Bang nucleosynthesis. We study carefully all light
elements up to Li. We correct a previous upper limit on estimated from He primordial abundance and we find interesting new
potential limits (depending on the value of the baryon-to-photon ratio) from
Li, whose production is governed to a large extent by Coulomb barriers. The
presently unclear observational situation concerning the primordial abundances
preclude a better limit than |\Delta \alpha/\alpha| \lsim 2\cdot 10^{-2}, two
orders of magnitude less restrictive than previous bounds. In fact, each of the
(mutually exclusive) scenarios of standard Big Bang nucleosynthesis proposed,
one based on a high value of the measured deuterium primordial abundance and
one based on a low value, may describe some aspects of data better if a change
in of this magnitude is assumed.Comment: 21 pages, eps figures embedded using epsfig macr
Constraints on the Variations of the Fundamental Couplings
We reconsider several current bounds on the variation of the fine-structure
constant in models where all gauge and Yukawa couplings vary in an
interdependent manner, as would be expected in unified theories. In particular,
we re-examine the bounds established by the Oklo reactor from the resonant
neutron capture cross-section of 149Sm. By imposing variations in \Lambda_{QCD}
and the quark masses, as dictated by unified theories, the corresponding bound
on the variation of the fine-structure constant can be improved by about 2
orders of magnitude in such theories. In addition, we consider possible bounds
on variations due to their effect on long lived \alpha- and \beta-decay
isotopes, particularly 147Sm and 187Re. We obtain a strong constraint on \Delta
\alpha / \alpha, comparable to that of Oklo but extending to a higher redshift
corresponding to the age of the solar system, from the radioactive life-time of
187Re derived from meteoritic studies. We also analyze the astrophysical
consequences of perturbing the decay Q values on bound state \beta-decays
operating in the s-process.Comment: 25 pages, latex, 5 eps figure
Financial stability, wealth effects and optimal macroeconomic policy combination in the United Kingdom: A New-Keynesian Dynamic Stochastic General Equilibrium Framework
This study derives an optimal macroeconomic policy combination for financial sector stability in the United Kingdom by employing a New Keynesian Dynamic Stochastic General Equilibrium (NK-DSGE) framework. The empirical results obtained show that disciplined fiscal and accommodative monetary policies stance is optimal for financial sector stability. Furthermore, fiscal indiscipline countered by contractionary monetary stance adversely affects financial sector stability. Financial markets, e.g. stocks and Gilts show a short-term asymmetric response to macroeconomic policy interaction and to each other. The asymmetry is a reflection of portfolio adjustment. However in the long-run, the responses to suggested optimal policy combination had homogenous effects and there was evidence of co-movement in the stock and Gilt markets
Big Bang nucleosynthesis and cosmic microwave background constraints on the time variation of the Higgs vacuum expectation value
We derive constraints on the time variation of the Higgs vacuum expectation
value through the effects on Big Bang nucleosynthesis (BBN) and the
cosmic microwave background (CMB). In the former case, we include the
(previously-neglected) effect of the change in the deuteron binding energy,
which alters both the He and deuterium abundances significantly. We find
that the current BBN limits on the relative change in \higgs are , where the
exact limits depend on the model we choose for the dependence of the deuteron
binding energy on \higgs.The limits from the current CMB data are much weaker.Comment: 5 pages including 5 figures, accepted for publication in Phys. Rev.
Primordial He4 Abundance Constrains the Possible Time Variation of the Higgs Vacuum Expectation Value
We constrain the possible time variation of the Higgs vacuum expectation
value () by recent results on the primordial abundance (). For
that, we use an analytic approach which enables us to take important issues
into consideration, that have been ignored by previous works, like the
-dependence of the relevant cross sections of deuterium production and
photodisintegration, including the full Klein- Nishina cross section.
Furthermore, we take a non-equilibrium Ansatz for the freeze-out concentration
of neutrons and protons and incorporate the latest results on the neutron
decay. Finally, we approximate the key-parameters of the primordial
production (the mean lifetime of the free neutron and the binding energy of the
deuteron) by terms of (where denotes the present theoretical
estimate). Eventually, we derive the relation and the most stringent
limit on a possible time variation of is given by: .Comment: Accepted for publication in IJT
- …