Physicists Investigate Possibility of an \’Unhiggs\’

One of the biggest goals of the LHC is to discover the Higgs boson, the only particle in the Standard Model that has not yet been observed. In general, physicists are pretty confident that the Higgs does in fact exist, although they have spent a lot of effort searching for the particle in less powerful accelerators without success. While patiently waiting for the LHC to reach its full energy and a Higgs particle to leave a signature in a detector, some physicists are investigating alternative scenarios. One of the most recent proposals is that the Higgs is not a particle, but an unparticle called the Unhiggs.

The Unhiggs idea was first suggested in a paper published in November 2009 by physicists David Stancato and John Terning of the University of California, Davis. The Unhiggs is not all that different from the Higgs, except that it demonstrates unparticle behavior and, subsequently, does not fit in with the Standard Model. While a particle has discrete parameters, the Unhiggs’ parameters are continuous. In this sense, the Unhiggs is itself a continuum, and can be thought of as a collection of many Higgs bosons, each carrying a fraction of the Unhigg’s total value.

“In particle physics, we are used to dealing with (surprise) particles,” Adam Falkowski, a physicist at Rutgers University, told PhysOrg.com. Falkowski and Manuel Pérez-Victoria of the University of Granada are also investigating the possibility of the Unhiggs. “One property of particles is a well defined mass. For an unstable particle (such as the Higgs boson in the Standard Model), we can experimentally determine the mass by measuring the momenta of its decay products and computing the so-called invariant mass. Particles show as bumps, or resonances, in the invariant mass spectrum or other kinematical distributions.

“Unparticles, on the other hand, do not have a well defined mass; in fact, an unparticle can be thought of as a superposition of an infinite number of particles with different masses. For this reason, unparticles don’t show up as resonances. Instead, they show up as subtle modifications of kinematical distributions measured by experiment, and therefore they can be difficult to spot.”

In their study, Stancato and Terning showed that the possibility of an Unhiggs is theoretically consistent (which was not obvious a priori). The physicists found that the Unhiggs can do many things that the Higgs does. For example, both the particle and the continuum possess a non-zero vacuum expectation value, which can “break electroweak symmetry” and “unitarize WW scattering” – abilities that are important for giving other particles mass, which is a fundamental role of the Higgs. In addition, the scientists found that the Unhiggs can do something that the Higgs cannot: provide a solution to the so-called little hierarchy problem.

More recently, Falkowski and Pérez-Victoria have further investigated the properties of the Unhiggs. In their study, they have explored certain experimental predictions of the Unhiggs proposal, such as how the Unhiggs affects precision observables measured by experiment. The scientists found that the Unhiggs is even more like the Higgs than previously thought, in that it closely mimics the Higgs for some light masses. They also found that the primary difference between the Unhiggs and the Higgs is due to their different propagators: while the Higgs’ propagator is mathematically described as a pole, the Unhiggs’ propagator is a branch. This characteristic is what makes the Unhiggs difficult to detect in collider experiments.

“Propagators are mathematical functions that are used for computing amplitudes in quantum theories,” Falkowski explained. “Amplitudes determine the probability of certain events to occur in our colliders. The ‘pole’ means that the propagator becomes very large for certain values of the momenta corresponding to the particle mass; mathematically, this is the origin of resonances in kinematical distributions measured by experiment. Propagators for unparticles do not have poles, but rather branch cuts (discontinuities of the imaginary part), and therefore unparticles do not show up as resonances.”

Instead, when the Unhiggs “decays,” it becomes suppressed, making its decay product mostly invisible. Still, the physicists say that a more detailed analysis of the collider’s constraints is necessary in order to determine if the Unhiggs might be observed. If physicists do find a way to determine its existence, the Unhiggs could possibly reveal information about the elusiveness of new physics beyond the Standard Model. Falkowski and Pérez-Victoria are currently working on a theoretical framework where not only the Higgs but also the W and Z bosons have unparticle components.

“At the present stage it\’s hard to say whether the idea is useful, that is to say whether it solves any problems that are troubling particle physicists,” Falkowski said. “Our approach in the paper was rather that the Unhiggs could be the reality, and explore consequences of that assumption. As I said, a priori it was far from obvious that the Unhiggs is theoretically consistent, or if it\’s consistent with all experimental results up to date. The usefulness of this direction of research is that it allows the experimental physicists to prepare their experiments such that the Unhiggs, if present, would not be missed.”

More information:
Adam Falkowski and Manuel Pérez-Victoria. “Electroweak precision observables and the unhiggs.” Journal of High Energy Physics. Doi:10.1088/1126-6708/2009/12/061 . http://arxiv.org/abs/0901.3777

David Stancato and JoDoi:10.1088/1126-6708ggs.” Journal of High Energy Physics. Doi:10.1088/1126-6708/2009/11/101 . http://arxiv.org/abs/0807.3961
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Right-handed and left-handed people do not see the same bright side of things

Despite the almost universal association of the right with life, right, positive and good things, and the left with death, inadequacy, negative and bad things, recent researches show that left-handed people hold the opposite association. Thus, left-handers become a critical case in which conceptual associations, result of a sensory-motor experience, and those that rely on linguistic and cultural uses, are contradictory. A sensory-motor experience in itself is capable of creating abstract conceptual associations.

These are the conclusions derived from various studies compiled by professor Julio Santiago de Torres, from the Department of Experimental Psychology and Behavioural Physiology at the University of Granada, Spain, who has conducted a bibliographic review on the subject, published in Ciencia Cognitiva: Revista Electrónica de Divulgación.

One of the latest works on this subject was undertaken by researcher Daniel Casasanto (Stanford University), who found out that left-handers tend to associate the left with nice and good things and the right with ugly and bad things, which goes against the enormous power of cultural context in which they live and the language they use.

Good things and bad things

In one of his experiments, Casasanto presented participants a diagram that depicts a character who was planning a trip to the zoo, and who loves zebras and thinks they are good, but dislikes pandas and thinks they are bad. The participant had to draw a zebra in the box that best represented good things and a panda in the box that best represented bad things.

Most of right-handed people located good things in the box on the right while left-handers placed them in the box on the left. Interestingly, only 14% of participants thought that his election had to do with what his dominant hand was.

Then, to see whether the left or right location could affect rating dimensions on abstract personality, he asked another group of participants to rate pairs of objects depicted in another drawing, indicating which of the two seemed more intelligent, more honest, more attractive and happier. And in a final experiment, participants were asked to assess which candidate would they chose for a job, or what product would they buy in a store.

In all tasks, right-handers tended to evaluate the object on the right better, while left-handers favoured the one on the left. Therefore, UGR professor says, «these results demonstrate that perceptuomotor experiences, in this case the greater ease and fluidity of interaction with one or another side of space, are sufficient to generate stable associations between specific dimensions, such as space, and concepts of a high degree of abstraction, such as kindness, intelligence or honesty.»

These data provide one of the first clear demonstrations that sensory-motor experience can exert a powerful influence on the conceptualization of even our most abstract ideas.

A wrong world

As professor Santiago explains, «a left-handed person has often the feeling of having been born in a wrong world. From scissors to computer keyboards designs, everything is projected for right-handers. The fact that left-handed people are able to adapt quite well to these manual controls that are contrary to their nature, indicates a first interesting fact that it is often overlooked: undoubtedly, there is a difference in motor ability between the dominant and the non-dominant hand, but it is far from being a great difference.»

In fact, the researcher points out, «speed and accuracy differences between the right and the left hand that are usually found, do not go beyond 10%. In addition, the left hand can be trained to high levels of implementation, as in the case of musicians or typists. In contrast with the intensive use of the right hand that characterizes an average right-handed person in over 90% of the tasks.

Julio Santiago recalls in his article that association between right and left with the symbolic systems of the world cultures «is deep, and reaches almost every aspect of life. Thus, right and left are respectively associated with aristocratic and common people, male and female, sacred and profane, good and bad. Eventually, these partnerships control aspects of life as varied as the position in which dead are buried, distribution of space in homes and churches, positions in which men and women sit at the table or in the temple and the hand chosen for saluting, swearing, eating or bathing.»

Moreover, Santiago points out, «even vocabulary is also full of similar facts such as, for example, the word «siniestro», which derives from sinister, «izquierda» in Latin.
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