Standard Model Higgs boson mass from inflation

We analyse one-loop radiative corrections to the inflationary potential in the theory, where inflation is driven by the Standard Model Higgs field. We show that inflation is possible provided the Higgs mass mH$m_H$ lies in the interval mmin<mH<mmax$m_{\min }<m_H<m_{\max }$, where mmin=[136.7+(mt−171.2)×1.95] GeV$m_{\min }=[136.7+(m_t-171.2)\times 1.95]\text{GeV}$, mmax=[184.5+(mt−171.2)×0.5] GeV$m_{\max }=[184.5+(m_t-171.2)\times 0.5]\text{GeV}$ and mt$m_t$ is the mass of the top quark. In the renormalization scheme associated with the Einstein frame the predictions of the spectral index of scalar fluctuations and of the tensor-to-scalar ratio practically do not depend on the Higgs mass within the admitted region and are equal to ns=0.97$n_s=0.97$ and r=0.0034$r=0.0034$ correspondingly.     

Running inflation in the Standard Model

An interacting scalar field with largish coupling to curvature can support a distinctive inflationary universe scenario. Previously this has been discussed for the Standard Model Higgs field, treated classically or in a leading log approximation. Here we investigate the quantum theory using renormalization group methods. In this model the running of both the effective Planck mass and the couplings is important. The cosmological predictions are consistent with existing WMAP5 data, with 0.967?ns?0.98$0.967?n_s?0.98$ (for Ne=60$N_e=60$) and negligible gravity waves. We find a relationship between the spectral index and the Higgs mass that is sharply varying for mh∼120–135 GeV$m_h\sim 120\text{–}135\text{GeV}$ (depending on the top mass); in the future, that relationship could be tested against data from PLANCK and LHC. We also comment briefly on how similar dynamics might arise in more general settings, and discuss our assumptions from the effective field theory point of view.     

Electron interactions in an antidot in the integer quantum Hall regime

A quantum antidot, a submicron depletion region in a two-dimensional electron system, has been actively studied in the past two decades, providing a powerful tool for understanding quantum Hall systems. In a perpendicular magnetic field, electrons form bound states around the antidot. Aharonov–Bohm resonances through such bound states have been experimentally studied, showing interesting phenomena such as Coulomb charging, h/2e$h/2e$ oscillations, spectator modes, signatures of electron interactions in the line shape, Kondo effect, etc. None of them can be explained by a simple noninteracting electron approach. Theoretical models for the above observations have been developed recently, such as a capacitive-interaction model for explaining the h/2e$h/2e$ oscillations and the Kondo effect, numerical prediction of a hole maximum-density-droplet antidot ground state, and spin-density-functional theory for investigating the compressibility of antidot edges. In this review, we summarize such experimental and theoretical works on electron interactions in antidots.     

Relativistic particles and the geometry of 4-D null curves

We study actions in (d+1)$(d+1)$-dimensions associated with null curves, mainly when d=3$d=3$, whose Lagrangian is a linear function on the curvature of the particle path, showing that null helices are always possible trajectories of the particles. We find Killing vector fields along critical curves of the action which correspond to the linear and the angular momenta of the particle. They provide two constants of the motion which can be interpreted in terms of the mass and the spin of the system. Moreover, we are able to integrate both the Euler–Lagrange equations and the Cartan equations in cylindrical coordinates around a certain plane.     

Euler–Heisenberg effective action and magnetoelectric effect in multilayer graphene

The low energy effective field model for the multilayer graphene (at ABC stacking) is considered. We calculate the effective action in the presence of constant external magnetic field B$B$ (normal to the graphene sheet). We also calculate the first two corrections to this effective action caused by the in-plane electric field E$E$ at E/B?1$E/B?1$ and discuss the magnetoelectric effect. In addition, we calculate the imaginary part of the effective action in the presence of constant electric field E$E$ and the lowest order correction to it due to the magnetic field (B/E?1$B/E?1$).     

Generalized Chaplygin gas model: Constraints from Hubble parameter versus redshift data

We examine observational constraints on the generalized Chaplygin gas (GCG) model for dark energy from the 9 Hubble parameter data points, the 115 SNLS Sne Ia data and the size of baryonic acoustic oscillation peak at redshift, z=0.35$z=0.35$. At a 95.4% confidence level, a combination of three data sets gives 0.67?As?0.83$0.67?A_s?0.83$ and −0.21?α?0.42$-0.21?\alpha ?0.42$, which is within the allowed parameters ranges of the GCG as a candidate of the unified dark matter and dark energy. It is found that the standard Chaplygin gas model (α=1$\alpha =1$) is ruled out by these data at the 99.7% confidence level.     

Inflaton mass in the νMSM inflation

We analyze the reheating in the modification of the ν  MSM (Standard Model with three right handed neutrinos with masses below the electroweak scale) where one of the sterile neutrinos, which provides the Dark Matter, is generated in decays of the additional inflaton field. We deduce that due to rather inefficient transfer of energy from the inflaton to the Standard Model sector reheating tends to occur at very low temperature, thus providing strict bounds on the coupling between the inflaton and the Higgs particles. This in turn translates to the bound on the inflaton mass, which appears to be very light 0.1 GeV?mI?10 GeV$0.1\text{GeV}?m_I?10\text{GeV}$, or slightly heavier then two Higgs masses 300 GeV?mI?1000 GeV$300\text{GeV}?m_I?1000\text{GeV}$.     

Bogolyubov approximation for diagonal model of an interacting Bose gas

We study, using the Bogolyubov approximation, the thermodynamic behavior of a superstable Bose system whose energy operator in the second-quantized form contains a nonlinear expression in the occupation numbers operators. We prove that for all values of the chemical potential satisfying μ>λ(0)$\mu >\lambda (0)$, where λ(0)?0$\lambda (0)?0$ is the lowest energy value, the system undergoes Bose–Einstein condensation.     

Model building by coset space dimensional reduction in eight-dimensions

We investigate gauge-Higgs unification models in eight-dimensional spacetime where extra-dimensional space has the structure of a four-dimensional compact coset space. The combinations of the coset space and the gauge group in the eight-dimensional spacetime of such models are listed. After the dimensional reduction of the coset space, we identified SO(10)$\mathrm{SO}(10)$, SO(10)×U(1)$\mathrm{SO}(10)\times \mathrm{U}(1)$ and SO(10)×U(1)×U(1)$\mathrm{SO}(10)\times \mathrm{U}(1)\times \mathrm{U}(1)$ as the possible gauge groups in the four-dimensional theory that can accomodate the Standard Model and thus is phenomenologically promising. Representations for fermions and scalars for these gauge groups are tabulated.     

Competing orders in one-dimensional half-integer fermionic cold atoms: A conformal field theory approach

The physical properties of arbitrary half-integer spins F=N−1/2$F=N-1/2$ fermionic cold atoms loaded into a one-dimensional optical lattice are investigated by means of a conformal field theory approach. We show that for attractive interactions two different superfluid phases emerge for F?3/2$F?3/2$: A BCS pairing phase, and a molecular superfluid phase which is formed from bound-states made of 2N   fermions. In the low-energy approach, the competition between these instabilities and charge-density waves is described in terms of ZN${\mathbb{Z}}_N$ parafermionic degrees of freedom. The quantum phase transition for F=3/2,5/2$F=3/2,5/2$ is universal and shown to belong to the Ising and three-state Potts universality classes respectively. In contrast, for F?7/2$F?7/2$, the transition is non-universal. For a filling of one atom per site, a Mott transition occurs and the nature of the possible Mott-insulating phases are determined.     

Search for solar axions with mass around 1 eV using coherent conversion of axions into photons

A search for solar axions has been performed using an axion helioscope which is equipped with a 2.3-m long 4 T superconducting magnet, a gas container to hold dispersion-matching gas, PIN-photodiode X-ray detectors, and a telescope mount mechanism to track the sun. A mass region around ma=1 eV$m_a=1\text{eV}$ was newly explored. From the absence of any evidence, analysis sets a limit on axion–photon coupling constant to be g_aγγ<5.6–13.4×¹⁰⁻¹⁰ GeV⁻¹$g_{a\gamma \gamma }<5.6\text{–}13.4\times {10}^{\mathrm{-10}}{\text{GeV}}^{\mathrm{-1}}$ for the axion mass of 0.84<ma<1.00 eV$0.84<m_a<1.00\text{eV}$ at 95% confidence level. It is the first result to search for the axion in the g_aγγ–ma$g_{a\gamma \gamma }\text{–}{m}_a$ parameter region of the preferred axion models with a magnetic helioscope.     

Chaotic inflation,radiative corrections and precision cosmology

We employ chaotic (?²${?}^2$ and ?⁴${?}^4$) inflation to illustrate the important role radiative corrections can play during the inflationary phase. Yukawa interactions of ?  , in particular, lead to corrections of the form −κ?⁴ln(?/μ)$-\kappa {?}^4\ln (?/\mu )$, where κ>0$\kappa >0$ and μ   is a renormalization scale. For instance, ?⁴${?}^4$ chaotic inflation with radiative corrections looks compatible with the most recent WMAP (5 year) analysis, in sharp contrast to the tree level case. We obtain the 95% confidence limits 2.4×¹⁰⁻¹⁴?κ?5.7×¹⁰⁻¹⁴$2.4\times {10}^{\mathrm{-14}}?\kappa ?5.7\times {10}^{\mathrm{-14}}$, 0.931?ns?0.958$0.931?n_s?0.958$ and 0.038?r?0.205$0.038?r?0.205$, where ns$n_s$ and r   respectively denote the scalar spectral index and scalar to tensor ratio. The limits for ?²${?}^2$ inflation are κ?7.7×¹⁰⁻¹⁵$\kappa ?7.7\times {10}^{\mathrm{-15}}$, 0.929?ns?0.966$0.929?n_s?0.966$ and 0.023?r?0.135$0.023?r?0.135$. The next round of precision experiments should provide a more stringent test of realistic chaotic ?²${?}^2$ and ?⁴${?}^4$ inflation.     

Experimental search for neutron–mirror neutron oscillations using storage of ultracold neutrons

The idea of a hidden sector of mirror partners of elementary particles has attracted considerable interest as a possible candidate for dark matter. Recently it was pointed out by Berezhiani and Bento that the present experimental data cannot exclude the possibility of a rapid oscillation of the neutron n to a mirror neutron n′ with oscillation time much smaller than the neutron lifetime. A dedicated search for vacuum transitions n→n^′$\mathrm{n}\to {\mathrm{n}}^{\prime }$ has to be performed at weak magnetic field, where both states are degenerate. We report the result of our experiment, which compares rates of ultracold neutrons after storage at a weak magnetic field well below 20 nT and at a magnetic field strong enough to suppress the seeked transitions. We obtain a new limit for the oscillation time of n–n′ transitions, τosc(90% C.L.)>414 s${\tau }_{\mathrm{osc}}(90\mathrm{\%}\text{C.L.})>414\text{s}$. The corresponding limit for the mixing energy of the normal and mirror neutron states is δm(90% C.L.)<1.5×¹⁰⁻¹⁸ eV$\delta m(90\mathrm{\%}\text{C.L.})<1.5\times {10}^{\mathrm{-18}}\text{eV}$.