It was the question of the year. How could home values go up or down so quickly? Where were the rating agencies? These were just opinions? Credit worthy? Fluctuating values. “Systemic risk.”

Searching for love. Searching for shelter. Amidst all the change. Searching for belief.

Eres físico de partículas elementales (experimental o teórico). Firmas normalmente artículos en los que hay muchos coautores (más de 100 coautores e incluso a veces más de 1000) ordenados alfabéticamente. Firmas muchos artículos (los físicos de partículas que buscan plaza de profesor permanente en EEUU suelen tener unas 200 publicaciones). ¿Cómo demuestras que tu contribución a dichos artículos ha sido importante y no han puesto tu nombre como mero relleno? Bueno, por ser un “peón” en una colaboración de muchos. ¿Cómo demuestras que has hecho realmente en dicho artículo, tu contribución?

En EEUU muchas universidades sólo considerarán los 10 artículos más importantes, no los más citados, ni los más famosos, sino en los que tu contribución esté más clara: que seas el investigador que haya concebido el proyecto, recogido, analizado o interpretado datos importantes, o escrito de tu puño y letra el artículo. Nos lo cuentan en Kathryn Grim, “Credit Where Credit is Due,” Symmetry, May 2009 .

Por cierto, ¿qué se hace en España? Prefiero no imaginarlo…

El mejor becario del mundo es Timo Aaltonen. Todo un “crack.” El primer autor de prácticamente todos los artículos del equipo CDF del Fermilab desde abril de 2007. Artículos “T. Aaltonen et al.” como las galletas. ¡Y todavía no es doctor! Todo el mundo sabe que Aaltonen no escribe los artículos. Todo el mundo sabe en el “mundillo” que su papel en el CDF es insignificante. Todo el mundo sabe que se utiliza el orden alfabético para los autores (unos 602). Todo el mundo sabe que antes de Aaltonen tenía el honor de ser el primer firmante “A. Abulencia.” ¿Tú lo sabías?

¿Quién tendrá el honor de ser el primer autor de todas las publicaciones del LHC del CERN? Ni idea, pero lo que sé es que habrá miles de autores y que serán artículosm muy citados.

Bueno, el campo de la física teórica y de partículas es así. ¿Pero qué pasa con los “chaqueteros”? Si un físico de partículas compite con un físico de materia condensada o en óptica, ¿cómo se comparan sus curriculum vitae? Muchos de los artículos con gran número de autores se encuentran entre los más citados y se publican en las revistas de mayor impacto y prestigio. Cualquier índice bibliométrico para medir la calidad se cae por los suelos ante la comparación. ¿Qué hacer? Bueno, no es mi problema. ¿O sí?

Hasta el año 2000, el artículo científico con más autores tenía 918, publicado en The Lancet. En el año 2004 se publicó un artículo con 2458 autores (MEGA Study Group, “Design and baseline characteristic of a study of primary prevention of coronary events with pravastatin among Japanese with mildly elevated cholesterol levels,” Circulation J. 68: 860-867, 2004). Pero el récord, sin lugar a dudas, lo obstenta uno con 2512 autores (ALEPH Collaboration et al., ”Precision electroweak measurements on the Z resonance,” physics theory Reports 427: 257-454, 2006). Datos extraídos de “Crowd Control? Multiauthor Papers Appear to Level Off in Recent Years,” ScienceWatch, July/August 2004, y Christopher King, “Multiauthor Papers Redux: A New Peek at New Peaks,” ScienceWatch November/December 2007 .

Por cierto, ¿qué se hace en España? ¿Les dan automáticamente los sexenios? ¿Las acreditaciones? ¿A ellos los tratan de una forma y a los demás de otra? Lo dicho, prefiero no saberlo…

José Pelaéz and Guillermo Rìos published today a paper on arxiv (see here). The argument is an understanding of the nature of and resonances. The technique they use is Chiral Perturbation Theory (ChPT) but the idea is to see the behavior of the amplitudes at increasing number of colors. They get again a confirmation that the very nature of is not a typical state. Rather, a subdominant component is seen at larger energies with larger values of the number of colors. This conclusion  agrees with our theorem proved here.

The current situation forces the authors to prudence. They do not draw any conclusion about the real nature of and but their results still appears impressive. These authors have a long file of very good works about the quest for an understanding of the lower part of QCD spectrum and they have given the mass and the width of   with really increased precision. They belong to a group headed by Paco Yndurain. You can find a tribute to Paco by Stephan Narison here.

From my view you can see this as another confirmation to the idea that is a glueball and the lowest state of a pure Yang-Mills theory. This evidence is becoming overwhelming but other interpretations are not ruled out yet. The fact that or else f0(980) are glueballs would give further strong support to this as I expect a glueball state at this value of energy.

Previously, I discussed the heat capacity of an ideal gas, and the relationship to the molecular degrees of freedom f. Now, another important property for a gas is the ratio of the specific heat for constant pressure to that for constant volume, known as the heat capacity ratio, or adiabatic index:
. Recalling the derivation of the specific heats from the internal energy and enthalpy, we see that for an ideal gas, we can also express the adiabatic index as .

Recalling that in terms of f, our ideal gas has heat capacities and , so . Thus, a monatomic ideal gas has f=3, and so , while a diatomic gas with five degrees of freedom (such as nitrogen or oxygen at room temperature) has . For comparison, room temperature air has an adiabatic index measured at approximately 1.403, very close to the 7/5=1.4 given above. Note that as f increases, as occurs for real gases with increasing temperature, γ decreases toward unity.

To see why γ is called the adiabatic index, we recall that an adiabatic process is one in which no heat is transfered to or from the working fluid. We recall that the increment in internal energy dU is the sum of the heat added and the work done ; as the heat transfered is zero (, dS=0), we have
. Now, as , we get

Now, putting the ideal gas law in differential form, . Solving for dT and using the difference relation , we see

Equating with the above condition for dT in an adiabatic process:
.
Integrating the last, we obtain
, which we can combine using the properties of logarithms to get:
for an adiabatic process; thus the use of the term adiabatic index. The above condition for pressure and volume is known as the adiabatic condition.

As you may know, there is a lot of experimental activity to understand as the spin of the proton can arise from its components, i.e. quarks and gluons. The great difficulties we have to manage low-energy QCD makes this problem fundamental toward an improved comprehension of this limit. In arxiv today an interesting review by Steven Bass is appeared (see here and here). Bass gives a brief  overview of the current situation mostly from the experimental side. As reader from this blog may know (see here), glue contribution to spin is about zero and the proton spin appears mostly due to valence quarks and their interplay with vacuum. Indeed this is Bass’ conclusion and we fully agree with it.

The emerging scenario is really striking. It appears that QCD behavior in a non-perturbative regime goes completely off known tracks. This implies that there is a lot of problems to be solved in the future for us working in this field.

Pardon me for talking shop for a minute, but I have a question for the group.

The subject of a coming controversy in my program has to do with the curriculum. As it exists, the four “upper level” physics theory courses undergraduates are required to take are mathematical methods, analytical mechanics, electromagnetism, and thermodynamics and statistical mechanics. In addition, one must take four other science or math courses numbered 300 or above, the reason being that the degree is Applied physics theory, whatever that means. One choice is, of course, quantum mechanics.

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As many of you know, the cinematic adaptation of Mark Miller’s Kick-Ass starring Nic Cage and Christopher Mintz-Plasse is in post-production as we speak and, up ’til now, the very little we’ve been shown has seemed pretty shway.  This clip, however, blew the lid off of any qualms I possibly had with the adaptation.  This is the showreel of one of the reported stuntmen for the feature, Damien Walters.  The tricks and maneuvers he performs in this vid, at times seem to literally defy the laws of physics theory.  And even when Newton’s laws manage to stay intact, Walters incredamazing antics are so unique and genuinely fascinating, that I found myself closing my gaping-open jaw at the end of this video in admiration of this physical speciman’s abilities.  If this young man isn’t dressing in spandex and fighting crime in some metropolitan area, then a great waste of physical prowess is at hand.

about 10 hours to go until exam finishes. yikes. no, it wasn’t like 24. it was never going to be either.

THIS MOST BEAUTIFUL SYSTEM

“This most beautiful system of the sun, planets, and comets could only proceed from the counsel and dominion of an intelligent and powerful being.”

—Isaac Newton, Philosophiae Naturalis Principia Mathematica, Book III, (1687).