Physics 234A: String Theory I
Fall 2015
Basic Info
Time: Mon and Fri, 1:10pm  2:30pm (lectures);
discussions TBA.
Place: 402 Le Conte Hall
Instructor:
Petr Hořava
(email: horava@berkeley.edu)
Office: 401 Le Conte Hall.
GSI: TBD.
This course will give a thorough introduction to modern string theory.
In the past two decades or so, string theory has become the dominant
theoretical framework for addressing questions about the fundamental
structure of matter in our Universe. It has produced many new ideas and
insights in other fields of physics,
ranging from particle phenomenology to quantum gravity, cosmology, and
more recently even to condensed matter systems.
Some of this surprising power of string theory is logically explained by the
fact that string theory represents a natural extension or completion of the
language of quantum manybody systems and quantum field theory, which makes
it relevant in all those diverse areas where the methods of manybody physics
play an important role. Basics of string theory should now be in every
theorist's vocabulary, regardless of the specific field of physics.
Our main goal in this semester will be twofold. On one hand, we will develop
some practical understanding of the basic elements and techniques of string
theory. On the other hand, we will also focus on understanding the "big
picture"  how string theory produces new ideas and techniques relevant to
other areas of physics besides particle phenomenology and quantum gravity.
In that part of the semester, we will particularly discuss some recent
interactions of string theory with
condensed matter (via the AdS/CFT duality, but also stimulating the
development of topological insulators), and with inflationary cosmology (which
we will frame in the language of the effective field theory of inflation).
Throughout the semester, I will also point out some of the open questions
and puzzles of our field. String theory is a live and rapidly
developing field, which promises that many interesting surprises are still to
come, especially in the crossdisciplinary areas of condensed matter,
cosmology, and perhaps others (AMO physics? Nonequilibrium systems? Quantum
computing?).
Anticipating such future developments is one of the most exciting challenges
in string theory today.
Specifically, in this semester we will cover the following six areas:
I. Introduction: Why strings?
II. The bosonic string.
III. Superstrings, heterotic strings, supergravity.
IV. Dbranes.
V. Mtheory and string dualities.
VI. Applications in condensed matter & inflationary cosmology.
The style will be somewhat similar to the style of my course taught in
Fall 2008,
Fall 2009, and
Fall 2011. However, as the field is evolving, we will take a novel, fresh
look at some of the basic questions and applications of string theory in the
context relevant for current research.
The main textbook is going to be
K. Becker, M. Becker and J.H. Schwarz, String Theory and MTheory. A Modern Introduction (Cambridge University Press, 2006).
we will occasionally use other resources, including the two volumes of Joe Polchinski's book, the classic two volumes of GreenSchwarzWitten, or the newer book by Elias Kiritsis (String Theory in a Nutshell), and sometimes even review papers from the arXiv.
We will also take a closer look at the new exciting book
D. Baumann and L. McAllister, Inflation and String Theory (Cambridge University Press, 2015),
just published by CUP in April.
Prerequisites
In order to make Physics 234A accessible to a wide audience of students from
varying areas of physics and cosmology, I will develop the material from first
principles, such that the course can be taken without any prior knowledge of
quantum field theory (for example, it could be taken concurrently with
 or even before  232A). Some basic understanding of quantum mechanics and
relativity is however assumed.
Homework Assignments
Homework assignments will be posted on this website weekly (or sometimes
biweekly). The assignments will be due at the day/time TBD.
Most homeworks will be assigned from the list of Homework problems in
Becker&Becker&Schwarz ([BBS]), unless stated explicitly otherwise.
Occasionally, the assignment will contain also solved Exercises from [BBS];
if so, the students are encouraged to solve the problem before they look at
the solution in [BBS].
horava@berkeley.edu
