Arcadian Functor

occasional meanderings in physics' brave new world

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Location: New Zealand

Marni D. Sheppeard

Thursday, October 29, 2009

LHC Era Begins

As the LHC begins operations, real tests were run on the beam through LHCb. The LHCb RICH detector has also seen its first particle from cosmic rays, as the two rings shown here.

Monday, October 26, 2009

Multiverse Mania

Matti Pitkanen points out that any reasonable quantum cosmology involves a multiverse, in some sense. Unfortunately, the word multiverse is too widely used in the painfully ludicrous context of stringy landscapes and the Dark Force, and this classical geometry essentially defines its meaning. If AF ever lapses into some strange use of the word, without clarifying its meaning, then you have permission to swear in the comments section.

It is quite difficult to figure out which multiverse advocacy group is the most impossible to forgive. Certainly the so called theoretical physicists are high on the list. But are the philosophers any less guilty? At least the physicists have the excuse that they were never required to take courses in the history and philosophy of science and, in true 20th century camaraderie, were rewarded for playing the game and forgetting about the problems that they were actually supposed to solve.

A professional philosopher of physics, on the other hand, should be able to dismiss the objective, observer independent multiverse with three words that they learned in kindergarten: I am thinking, therefore I exist. Descartes, and many others, must be turning in their graves, to see science so debased.

Sunday, October 25, 2009

ViXra Video

Thanks to Phil Gibbs for his video on the String Wars. Make sure you watch it right to the end.

Saturday, October 24, 2009

White Dwarfs

A Kiwi astronomer has been telling me about his work on white dwarf stars, which are the end states of around 99% of all stars. In theory, white dwarfs cool quickly due to neutrino emission from the core in a photon decay process

$\gamma \mapsto \nu + \overline{\nu}$

from photons that acquire an effective mass due to the plasma medium. This mass depends on the core density of the star. One aims to measure cooling rates for such stars by observing changes in the periods of their pulsation.

A Mt John result focuses on the fairly stable pulsating hot dwarf star EC20058-5234, which is about $0.55$ the mass of the sun. This is the only known stable white dwarf of DBV type. For such a hot star, plasmon neutrino cooling should be far more important than photon emission from surface processes. However, constraints on plasmon neutrino emission for this star, in terms of period decay, currently lie around $10^{-13} s s^{-1}$.

Some authors have also considered novel cooling processes for white dwarfs, such as axion emission.

Friday, October 23, 2009

Mt John News II

I seem to be spending rather a lot of time sending futile emails to U.S. institutions requesting support for postdoctoral fellowship applications. I am doing the same with Oxford. Meanwhile the stunning spring weather continues and I am enjoying the local walks.

Wednesday, October 21, 2009

The LHC Era

My visit to the University of Warwick in September naturally made me regret my ignorance of the LHCb experiment. Very little time remains for theorists to get off their asses (yours truly included) and make some decent predictions.

The LHCb experiment will study bottom quark physics. It consists of a vertex detector, track reconstruction capabilities, and two Cherenkov detectors for velocity measurements and particle identification, which will separate pions and kaons.

In particular, LHCb will further study the beyond the standard model CDF result for the CP violation parameter $2 \beta_{s}$ in decays of the meson $B_{s}^{0}$. The definition of this parameter is

$2 \beta_{s} = 2 \textrm{arg} \frac{V_{ts} V_{tb}^{*}}{V_{cs} V_{cb}^{*}}$

in terms of the usual CKM matrix parameters. As CDF points out (cheers, Tommaso):
The presence of physics beyond the standard model could contribute additional processes and modify the magnitude
or the phase of the mixing amplitude.
The Standard Model predicts $2 \beta_{s} = 0.04$, in contrast to the observation that $2 \beta_{s}$ lies in the interval $[0.32,2.82]$, with $68%$ confidence. The D0 experiment also reports on this decay.

Tuesday, October 20, 2009

M Theory Lesson 300

Last time we considered the relation between $\Omega_{B}$, the baryonic mass fraction, and two phases appearing in Carl Brannen's mass matrices. A more natural choice involves the angles

$\phi = \frac{1}{9 \pi}$
$\alpha = \frac{1}{24}$,

where $\alpha$ comes from the phase $\pi / 12$. The difference $( \alpha - \phi )$ appears in mass relations for neutrinos, charged leptons and hadrons. We now have

$24 \alpha - 27 \phi = \Omega_{B}$

where $24 \alpha = 1$, the total of baryonic and dark matter components. Both the numbers $24$ and $27$ have a multitude of interesting number theoretic properties which M theorists enjoy. For example, $27$ is the dimension of the octonionic exceptional Jordan algebra, which in terms of $3 \times 3$ Hermitian matrices has a $24$ dimensional component coming from three octonion elements. The number $24$ decomposes into $2^3 \cdot 3$, and in Brannen's path integrals the $3$ indexes particle generation number, and $2$ stands for the fermionic spin quantum number.

Monday, October 19, 2009

Motives in Tokyo

Thanks to Motivic Stuff for pointing out a wonderful workshop in December in Tokyo: International Workshop on Motives.

Sunday, October 18, 2009

Mt John News

The snow has gone now and the weather alternates between the usual warm, clear skies and today's cold rain. I have been bathing for hours in the hot springs, eating the excellent local Japanese food, and walking with friends from Wanaka. We discussed my job options, for when I return from Australia in December. Cleaning is more appealing than waitressing, but in the sparsely populated countryside these jobs are less reliable.

One original suggestion was motivational speaker. Not bad, heh? Can you see me in a white shirt, grey suit and red tie? Earning big bucks? Yeah, right.

Meanwhile, back in the Mt John kitchen, a local astronomer assured me (entirely without prompting) that he appreciated the compelling evidence for large primordial black holes. The Milky Way black hole, which we have actually observed through the remarkable motion of orbiting objects, is far too massive to have evolved via standard theories of stellar and galactic evolution.

Thursday, October 15, 2009

Major Meltdown

Lest there be anyone remaining under the delusion that all is well in the world of physics ...

Today Woit discusses the predictable actions of the arxiv over the backward causation joke theory. This follows a jaw dropping plunge by Carroll, who was already swimming in the murky depths of the Multiverse*, into a confidant explanation of the plausibility of backward causation ideas given the non local nature of quantum gravity:
Because they are not actually crackpots, they even admit what they’re doing — in their own words, “Our model with an imaginary part of the action begins with a series of not completely convincing, but still suggestive, assumptions.”
Well, it must be all right then, mustn't it? Or is there perhaps another scent in the air? In the words of Alberich: you eternal revellers! Beware!

*The Multiverse: the bandwagon idea that quantum information theory has won the String Wars, but that mainstream theory will still be hunky dory with that.

Tuesday, October 13, 2009

Quote of the Month

From Overbye's article in The New York Times:
In an unpublished essay, Dr. Nielson said of the theory, “Well, one could even almost say that we have a model for God.” It is their guess, he went on, “that He rather hates Higgs particles, and attempts to avoid them.”

This malign influence from the future, they argue, could explain why the United States Superconducting Supercollider, also designed to find the Higgs, was canceled in 1993 after billions of dollars had already been spent, an event so unlikely that Dr. Nielsen calls it an “anti-miracle.”

You might think that the appearance of this theory is further proof that people have had ample time — perhaps too much time — to think about what will come out of the collider...

Sunday, October 11, 2009

M Theory Lesson 299

Recall that in the charged lepton and neutrino mass matrices, there is a peculiar phase given by the fraction

$\phi = \frac{1}{9 \pi}$,

in contrast to the cubed root of unity, which corresponds to the rational fraction $\omega = 1/3$. We have seen these numbers before. Observe that

$\frac{1}{3} \omega - 3 \phi = \frac{1}{9} \frac{\pi - 3}{\pi} = \frac{1}{9} \Omega_{B}$,

where $\Omega_{B} = 0.0450703$ is the baryonic matter fraction, first computed by Louise Riofrio in her varying speed of light cosmology. In other words, to put it more simply,

$27 \phi = \Omega_{DM}$,

the dark matter fraction. One suspects that the factor of $27 = 3^3$ is due to the dimensionality of the information space required to describe the dark matter quantum numbers.

Friday, October 09, 2009

From Christchurch

Now 4.50am in Christchurch and I'm wide awake. It turns out that Oxford University have yet again had difficulties making foreign salary payments, and they neglected to pay me last month. Fortunately, I pre-booked all buses and am heading to Mt John this morning. Heavy snow is expected.

Sunday, October 04, 2009

Thank You Oxford

On March 4 the Heathrow bus dropped me off on High St. Bleary eyed, I lifted my head and saw the plaque to Boyle on the stone wall beside me, and it made me smile. I dragged my broken suitcase across the cobblestones to the gate at Oriel, where they were not expecting me. But a few phone calls later, I found myself in a comfortable room right in the city, where I enjoyed my first night.

At first, with weariness and disbelief that I should find myself here at all, there was only the shock of a functioning city, with its crowds and its garbage, its generosity and corruption. My student room on Cowley Rd was noisy at night, and it was over three months before I finally settled at home in Norham Rd.

And then it was summer. I had discovered the quietest corners of the large college gardens, my favourite chapels, and my favourite walks in the countryside. I was taken to lunch and dinner at Jesus and Balliol colleges. There were wonderful mathematics workshops and endless lectures to attend. The physicists were friendly. What more could I ask for than this? I will not forget you.

One night an old man at the Sheldonian told me that, in recent years, the light had changed. He said that now when he looked at the Magdalen tower in the afternoon, it did not seem real. We looked across the street to Trinity, and it was a beautiful night.

Fare well, Oxford. How fortunate I am, to have seen your dreaming spires.

M Theory Lesson 298

A product of two Markov type limits is one way of writing down a six parameter $3 \times 3$ matrix with distinct elements. For this matrix to be Hermitian, we require that $a' = \overline{a}$, $b' = \overline{b}$ and $c' = \overline{c}$, obtaining a six real parameter class of Hermitian matrices of the form $H = A A^{\dagger}$.

Note that a general complex transition matrix $M$, with fixed column sum, satisfies a Markov type rule: a column sum $S$ for $M$ goes to a sum $S^{2}$ for $M^{2}$. Thus for $S = 1$, the limiting operator still has the Markov property. For any such complex $M$, there is then associated a unique Hermitian matrix $A A^{\dagger}$, where $A$ is the long time limit. This process reduces the $6$ complex parameters of $M$ to $3$.

Thursday, October 01, 2009

A Day Out

Criminally decadent it may be, but since the probability of returning is so low, I could not resist ... tomorrow.