e-mail addresses: email@example.com or firstname.lastname@example.org
Publications and Citations at Google Scholar
Physics Research Interests:
The main thrust of my research in High Energy Physics is in elucidating the strongly interacting sector of the Standard Model of elementary particle interactions (interactions of quarks and gluons and the phenomenology of mesons and baryons made up of these elementary particles) using lattice Quantum Chromodynamics (Lattice QCD). The observables we have calculated include the hadron spectrum, quark masses, chiral properties of hadrons, glueballs, decay constants, semi-leptonic form factors, form factors for rare radiative decays of B mesons, matrix elements of 4-fermion operators and their B parameters and QCD at finite temperature. To understand the QCD vacuum we have also investigated chiral symmetry breaking and topology on the lattice.
Large scale simulations during 1988-2000 were done under the auspices of the DoE Grand Challenges awards. Over this period simulations were carried out on Crays and a number of parallel supercomputers including the Thinking Machines CM-2 and CM-5, the SGI Origin 2000 at the Advanced Computing Laboratory at Los Alamos, the Cray T3E at NERSC and commodity clusters. At Los Alamos, I also contributed to the development of high performance parallel computing.
A colloquium titled Discovering elementary particles and determining their masses (5.6 MB pdf file LA-UR-03-6215) describes how elementary particles are identified and how their masses are determined in high energy experiments. It also discusses how simulations of lattice QCD are used to estimate the masses of quarks which are not seen as isolated states in nature.
Since 2006, Ron Soltz and I have been co-leading the HotQCD collaboration collaboration to understand QCD at finite temperature using lattice QCD. We are using the Asqtad, p4 and HISQ improved staggered actions developed by the MILC and RBC-Bielefeld collaborations to simulate (2+1) and (2+1+1) flavor QCD at finite temperature on the BlueGene Q at LLNL and supercomputers at Fermilab, ANL and at other centers. Our goal is to elucidate the nature of the chiral and deconfining transition and determine the QCD equation of state over the temperature range 150-700 MeV relevant to heavy ion experiments at RHIC and LHC. HotQCD publications on these topics include
We are using Lattice QCD to calculate the matrix elements of quark bilinear quark operators between neutron and proton states. These matrix elements are needed to relate precision measurements of neutron decay to theory and to look for signatures of new physics at the TeV scale. The high precision experiment measuring neutron decay parameters is being done at Los Alamos using an ultra-cold neutron source. Papers formulating this project, results and the status of the calculations are
Calculations of matrix elements of novel CP violating operators that arise in the effective field theory analysis of new physics at the TeV scale and could make contributions to the neutron electric dipole moment that are large enough to explain baryogenesis.
Calculations of matrix elements of light cone operators within the proton state that shed light on the contribution of the angular momentum of quarks to the proton spin. Of particular interest is the extraction of the Sivers and Boer-Mulders distribution functions.
In addition to particle physics, I have also worked on determining the critical exponents of Statistical Mechanics systems, in particular the Ising and XY models. My favorite methods are Monte Carlo Renormalization Group and finite size scaling. Topcited papers include
Energy is key to development. The twentieth century was dominated by fossil fuels -- oil, coal and gas. Today we are faced with declining production of conventional oil in many parts of the world. Natural gas is considered the bridge fuel and its use is growing. The USA and many other parts of the world are increasingly dependent on unstable areas for their oil and natural gas supplies. Energy security is a key driver of geo-politics. Equally important, the environmental impact of burning fossil fuels has become global and there is emerging concensus regarding the urgency to address global warming. Current cumulative investment in fossil fuels already exceeds $40 trillion. Furthermore, China, India and the USA have hundreds of new coal fired power plants in planning and construction stages that will not be CO2 neutral and will continue to be in operation for most of this century. Such a large system will take a long time to change even under the best of circumstances. It is, therefore, important to plan, develop and transition to carbon neutral sources/technologies. At the same time we must ensure the availability of affordable energy for the global population so that development and opportunities are shared. Recent colloquia on this topic include
The Global Energy Observatory (GEO): Understanding the dynamics of change in energy systems
GEO is a free interactive website (a moderated Wiki) containing databases and tools developed collaboratively to make the global energy systems available to all interested readers. Our goal in building GEO is to collect, collate, manage and display data and integrate it with analysis tools to help people understand energy systems and their networks by performing real time analysis.
HIV/AIDS, Public Health and Education in the Developing World:
Since January 1999 I have been involved in developing educational material for accelerating the spread of awareness on disease prevention (in particular for HIV/AIDS), health care, education, and enviornmental among school students, industrial workers, villagers, and the public in general. Summary of my work in India can be found at AIDS Crisis in India. Based on my experiences and work in India and New Mexico, I have written a number of articles that are archived at MY WORK. In particular, a detailed analysis of the underlying reasons for the spread of HIV/AIDS in India, its consequences for development and security, and mitigation strategies is presented in the monograph Risky Sex, Addictions, and Communicable Diseases in India: Implications for Health, Development, and Security.
In a recent colloquium at Stanford and NREL, I make the connection between HIV/AIDS and the future of the poor, illiterate and marginalized populations and argue, using India as an example, why business as usual will not suffice, and why we need to help the poor in developing countries make the transition to the knowledge society (4.7 MB pdf file LA-UR-05-3139). Another talk at the University of Chicago discuses HIV, Empowerment, and how concerned people can help. (LAUR-07-3557)
Stopping the spread of HIV/AIDS is not just a matter of awareness, or of access to retroviral drugs, or of working health care systems, or of education, or of removing violence to women, or of GLT rights, or of providing job skills and jobs, or of good governance or of poverty. It is about all these issues and much more. Increasingly I believe that development requires and needs a holistic approach at all levels. To this end, a framework for a coupled systems analysis is presented in Five Global Grand Challenges. A related talk The Dynamics of change: India a case study analyzes the fast pace of change taking place globally and highlights four areas of priority that urgently need investment for accelerating the process of providing opportunities to the poor.