Quarkonium Mass Splitting Revisited: Effects of Closed Mesonic Channels

Modifications of the mass spectrum the quarkonium induced by its virtual dissociation into a pair of heavy mesons is considered. Coupling between quark and mesonic channels results in noticeable corrections to spin-dependent mass splitting. In particular, the observable hierarchy of mass splittings in the $\chi_c, \chi_b$ and $\chi'_b$ multiplets is reproduced.Comment: 9 pages, plain LaTe

Emotional abuse in sport: A case study of trichotillomania in a prepubescent female gymnast

This article is made available through the Brunel Open Access Publishing Fund. Copyright @ 2013 Gervis M, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Despite improved legislation in most countries, child abuse in sport continues to exist but is a problem which is often under reported or ignored. In elite sport ‘suffering’ is not uncommon and hence sometimes child abuse is sometimes unrecognised, de-emphasised or easily dismissed as part of a collective experience that is perceived to be necessary to ‘create’ elite athletes. However, even swearing, anger, raised voices and negative comments directed at child athletes by coaches is considered abuse and can, when regular and routine, cause long term wellbeing and health issues. Self-harm can be a consequence and here self-harm in the form of trichotillomania, self hair-pulling, is reported for the first time as a secondary consequence of abuse. The 12 year old female gymnast, subject of this case study, presented with this impulse control disorder as defined by the American Psychiatric Association and was successfully treated using cognitive behavioural therapy. However, the training environment, including coach behaviour, did not change and so the gymnast remained at risk of recurrence of self-harm. Such environments in sport have many characteristics in common with and reminiscent of religious cults; sacrifice, isolation, shared obsession, a charismatic leader, and often in the presence of severe calorie restriction. As a consequence of ageing, growth, injury and an unchanging abusive environment, a year later the gymnast retired from the sport

Absence of hyperuniformity in amorphous hard-sphere packings of nonvanishing complexity

We relate the structure factor $S(\mathbf{k} \to \mathbf{0})$ in a system of jammed hard spheres of number density $\rho$ to its complexity per particle $\Sigma(\rho)$ by the formula $S(\mathbf{k} \to \mathbf{0})=-1/ [\rho^2\Sigma''(\rho)+2\rho\Sigma'(\rho)]$. We have verified this formula for the case of jammed disks in a narrow channel, for which it is possible to find $\Sigma(\rho)$ and $S(\mathbf{k})$ analytically. Hyperuniformity, which is the vanishing of $S(\mathbf{k} \to \mathbf{0})$, will therefore not occur if the complexity is nonzero. An example is given of a jammed state of hard disks in a narrow channel which is hyperuniform when generated by dynamical rules that produce a non-extensive complexity.Comment: 5 pages, 3 figure

Understanding the ideal glass transition: Lessons from an equilibrium study of hard disks in a channel

We use an exact transfer-matrix approach to compute the equilibrium properties of a system of hard disks of diameter $\sigma$ confined to a two-dimensional channel of width $1.95\,\sigma$ at constant longitudinal applied force. At this channel width, which is sufficient for next-nearest-neighbor disks to interact, the system is known to have a great many jammed states. Our calculations show that the longitudinal force (pressure) extrapolates to infinity at a well-defined packing fraction $\phi_K$ that is less than the maximum possible $\phi_{\rm max}$, the latter corresponding to a buckled crystal. In this quasi-one-dimensional problem there is no question of there being any \emph{real} divergence of the pressure at $\phi_K$. We give arguments that this avoided phase transition is a structural feature -- the remnant in our narrow channel system of the hexatic to crystal transition -- but that it has the phenomenology of the (avoided) ideal glass transition. We identify a length scale $\tilde{\xi}_3$ as our equivalent of the penetration length for amorphous order: In the channel system, it reaches a maximum value of around $15\,\sigma$ at $\phi_K$, which is larger than the penetration lengths that have been reported for three dimensional systems. It is argued that the $\alpha$-relaxation time would appear on extrapolation to diverge in a Vogel-Fulcher manner as the packing fraction approaches $\phi_K$.Comment: 17 pages, 16 figure

Measurement of tan beta in associated t H^\pm Production in gamma gamma Collisions

The ratio of neutral Higgs field vacuum expectation values, tan beta, is one of the most important parameters to determine in type-II Two-Higgs Doublet Models (2HDM), specifically the Minimal Supersymmetric Standard Model (MSSM). Assuming the energies and integrated luminosity of a future high energy e^+e^- linear collider of sqrt{s}=500, 800, 1000, and 1500 GeV and L=1 ab^{-1} we show that associated t H^+/- production in gamma gamma collisions can be used to make an accurate determination of tan beta for low and high tan beta by precision measurements of the gamma gamma -> H^+/- t + X cross section.Comment: 7 pages, 11 figures, uses REVTEX