Constraining a fourth generation of quarks: non-perturbative Higgs boson mass bounds

We present a non-perturbative determination of the upper and lower Higgs boson mass bounds with a heavy fourth generation of quarks from numerical lattice computations in a chirally symmetric Higgs-Yukawa model. We find that the upper bound only moderately rises with the quark mass while the lower bound increases significantly, providing additional constraints on the existence of a straight-forward fourth quark generation. We examine the stability of the lower bound under the addition of a higher dimensional operator to the scalar field potential using perturbation theory, demonstrating that it is not significantly altered for small values of the coupling of this operator. For a Higgs boson mass of $\sim125\mathrm{GeV}$ we find that the maximum value of the fourth generation quark mass is $\sim300\mathrm{GeV}$, which is already in conflict with bounds from direct searches.Comment: 6 pages, 2 figure

Housing risk and return: Evidence from a housing asset-pricing model

This paper investigates the risk-return relationship in determination of housing asset pricing. In so doing, the paper evaluates behavioral hypotheses advanced by Case and Shiller (1988, 2002, 2009) in studies of boom and post-boom housing markets. The paper specifies and tests a multi-factor housing asset pricing model. In that model, we evaluate whether the market factor as well as other measures of risk, including idiosyncratic risk, momentum, and MSA size effects, have explanatory power for metropolitan-specific housing returns. Further, we test the robustness of the asset pricing results to inclusion of controls for socioeconomic variables commonly represented in the house price literature, including changes in employment, affordability, and foreclosure incidence. We find a sizable and statistically significant influence of the market factor on MSA house price returns. Moreover we show that market betas have varied substantially over time. Also, results are largely robust to the inclusion of other explanatory variables, including standard measures of risk and other housing market fundamentals. Additional tests of model validity using the Fama-MacBeth framework offer further strong support of a positive risk and return relationship in housing. Our findings are supportive of the application of a housing investment risk-return framework in explanation of variation in metro-area cross-section and time-series US house price returns. Further, results strongly corroborate Case-Shiller survey research indicating the importance of speculative forces in the determination of U.S. housing returns

The Influence of Public Policy on Health, Wealth and Mortality

In this project we extend an augmented lifecycle model, incorporating a Grossman-style model of health capital, to enhance understanding of factors influencing consumption, wealth and health. We develop three primary results when using the model to explore the effects of stylized versions of Medicare and Social Security on wealth and longevity. First, our model calibration implies consumption and health are complements. As health depreciates with age, households will get less utility from consumption than would be in the case of a lifecycle model that does not endogenize health. Second, it appears that forward-looking households, when confronted by a substantially reduced safety net, will respond by reducing consumption and by reducing their health investment and therefore longevity. Third, there is a potentially important difference between short- and long- run responses to policy.

What Replacement Rates Should Households Use?

Common financial planning advice calls for households to ensure that retirement income exceeds 70 percent of average pre-retirement income. We use an augmented life-cycle model of household behavior to examine optimal replacement rates for a representative set of retired American households. We relate optimal replacement rates to observable household characteristics and in doing so, make progress in developing a set of theory-based, but readily understandable financial guidelines. Our work should be a useful building block for efforts to assess the adequacy of retirement wealth preparation and efforts to promote financial literacy and well-being.

Health and Wealth in a Life Cycle Model

This paper presents a preliminary model of health investments over the life cycle. Health affects both longevity and provides flow utility. We analyze the interplay between consumption choices and investments in health by solving each household’s dynamic optimization problem to obtain predictions on health investments and consumption choices over the lifecycle. Our preliminary model does a good job of matching the distribution of medical expenses across households in the sample. We illustrate the scope of future model applications by examining the effects of a stylized Medicare program on patterns of wealth and mortality.

Are All Americans Saving ‘Optimally’ for Retirement?

Many people fear that Americans are preparing poorly for retirement. But developing rigorous evidence on this issue is difficult. In this paper we briefly discuss evidence on the adequacy of retirement wealth accumulation. We conclude that existing descriptive evidence does not seem consistent with dire assessments of poor financial preparation. We then extend the straightforward, but computationally complex dynamic programming approach used in our earlier work to assess the adequacy of retirement wealth preparation of Americans born before 1954. We find only 4 percent of HRS households have net worth below their optimal targets in 2004, though this percentage is somewhat higher for more recent HRS cohorts. While our work is preliminary, we find little evidence that Americans born before 1954 have prepared poorly for retirement.