‘So people know I'm a Sikh’: Narratives of Sikh masculinities in contemporary Britain

This article examines British-born Sikh men's identification to Sikhism. In particular, it focuses on the appropriation and use of Sikh symbols amongst men who define themselves as Sikh. This article suggests that whilst there are multiple ways of ‘being’ a Sikh man in contemporary post-colonial Britain, and marking belonging to the Sikh faith, there is also a collectively understood idea of what an ‘ideal’ Sikh man should be. Drawing upon Connell and Messerschmidt's discussion of locally specific hegemonic masculinities (2005. “Hegemonic Masculinity: Rethinking the Concept.” Gender and Society 19 (6): 829–859), it is suggested that an ideal Sikh masculine identity is partly informed by a Khalsa discourse, which informs a particular performance of Sikh male identity, whilst also encouraging the surveillance of young men's activities both by themselves and by others. These Sikh masculinities are complex and multiple, rotating to reaffirm, challenge and redefine contextualised notions of hegemonic masculinity within the Sikh diaspora in post-colonial Britain. Such localised Sikh masculinities may both assert male privilege and reap patriarchal dividends (Connell, W. 1995. Masculinities. Cambridge: Polity Press), resulting in particular British Sikh hegemonic masculinities which seek to shape the performance of masculinity, yet in another context these very same performances of masculinity may also signify a more marginalised masculinity vis-à-vis other dominant hegemonic forms

Feshbach resonances in ultracold 85Rb-87Rb and 6Li-87Rb mixtures

We present an analysis of experimentally accessible magnetic Feshbach resonances in ultra-cold hetero-nuclear 85Rb-87Rb and 6Li-87Rb mixtures. Using recent experimental measurements of the triplet scattering lengths for 6Li-87Rb and 7Li-87Rb mixtures and Feshbach resonances for one combination of atomic states, we create model potential curves and fine tune them to reproduce the measured resonances and to predict the location of several experimentally relevant resonances in Li-Rb collisions. To model 85Rb-87Rb collisions, we use accurate Rb_2 potentials obtained previously from the analysis of experiments on 87Rb-87Rb collisions. We find resonances that occur at very low magnetic fields, below 10 G, which may be useful for entanglement generation in optical lattices or atom chip magnetic traps.Comment: 8 pages, 5 figure

Collective Oscillations of Strongly Correlated One-Dimensional Bosons on a Lattice

We study the dipole oscillations of strongly correlated 1D bosons, in the hard-core limit, on a lattice, by an exact numerical approach. We show that far from the regime where a Mott insulator appears in the system, damping is always present and increases for larger initial displacements of the trap, causing dramatic changes in the momentum distribution, $n_k$. When a Mott insulator sets in the middle of the trap, the center of mass barely moves after an initial displacement, and $n_k$ remains very similar to the one in the ground state. We also study changes introduced by the damping in the natural orbital occupations, and the revival of the center of mass oscillations after long times.Comment: 4 pages, 5 figures, published versio

Self-energy corrections in an antiferromagnet -- interplay of classical and quantum effects on quasiparticle dispersion

Self-energy corrections due to fermion-magnon interaction are studied in the antiferromagnetic state of the $t-t'-t''$ Hubbard model within the rainbow (noncrossing) approximation in the full $U$ range from weak to strong coupling. The role of classical (mean-field) features of fermion and magnon dispersion, associated with finite $U,t',t''$, are examined on quantum corrections to quasiparticle energy, weight, one-particle density of states etc. A finite-$U$ induced classical dispersion term, absent in the $t-J$ model, is found to play an important role in suppressing the quasiparticle weight for states near ${\bf k}=(0,0)$, as seen in cuprates. For intermediate $U$, the renormalized AF band gap is found to be nearly half of the classical value, and the weak coupling limit is quite non-trivial due to strongly suppressed magnon amplitude. For finite $t'$, the renormalized AF band gap is shown to vanish at a critical interaction strength $U_c$, yielding a spin fluctuation driven first-order AF insulator - PM metal transition. Quasiparticle dispersion evaluated with the same set of Hubbard model cuprate parameters, as obtained from a recent magnon spectrum fit, provides excellent agreement with ARPES data for $\rm Sr_2 Cu O_2 Cl_2$.Comment: 11 pages, 17 figure

Constraints on millicharged particles with low threshold germanium detectors at Kuo-Sheng Reactor Neutrino Laboratory

Relativistic millicharged particles ($\chi_q$) have been proposed in various extensions to the Standard Model of particle physics. We consider the scenarios where they are produced at nuclear reactor core and via interactions of cosmic-rays with the earth's atmosphere. Millicharged particles could also be candidates for dark matter, and become relativistic through acceleration by supernova explosion shock waves. The atomic ionization cross section of $\chi_q$ with matter are derived with the equivalent photon approximation. Smoking-gun signatures with significant enhancement in the differential cross section are identified. New limits on the mass and charge of $\chi_q$ are derived, using data taken with a point-contact germanium detector with 500g mass functioning at an energy threshold of 300~eV at the Kuo-Sheng Reactor Neutrino Laboratory.Comment: 8 pages, 7 figure