Coherence as ultrashort pulse train generator

Intense, well-controlled regular light pulse trains start to play a crucial role in many fields of physics. We theoretically demonstrate a very simple and robust technique for generating such periodic ultrashort pulses from a continuous probe wave which propagates in a dispersive thermal gas media

Optimal refrigerator

We study a refrigerator model which consists of two $n$-level systems interacting via a pulsed external field. Each system couples to its own thermal bath at temperatures $T_h$ and $T_c$, respectively ($\theta\equiv T_c/T_h<1$). The refrigerator functions in two steps: thermally isolated interaction between the systems driven by the external field and isothermal relaxation back to equilibrium. There is a complementarity between the power of heat transfer from the cold bath and the efficiency: the latter nullifies when the former is maximized and {\it vice versa}. A reasonable compromise is achieved by optimizing the product of the heat-power and efficiency over the Hamiltonian of the two system. The efficiency is then found to be bounded from below by $\zeta_{\rm CA}=\frac{1}{\sqrt{1-\theta}}-1$ (an analogue of the Curzon-Ahlborn efficiency), besides being bound from above by the Carnot efficiency $\zeta_{\rm C} = \frac{1}{1-\theta}-1$. The lower bound is reached in the equilibrium limit $\theta\to 1$. The Carnot bound is reached (for a finite power and a finite amount of heat transferred per cycle) for $\ln n\gg 1$. If the above maximization is constrained by assuming homogeneous energy spectra for both systems, the efficiency is bounded from above by $\zeta_{\rm CA}$ and converges to it for $n\gg 1$.Comment: 12 pages, 3 figure

Magnetic and quantum entanglement properties of the distorted diamond chain model for azurite

We present the results of magnetic properties and entanglement of the distorted diamond chain model for azurite using pure quantum exchange interactions. The magnetic properties and concurrence as a measure of pairwise thermal entanglement have been studied by means of variational mean-field like treatment based on Gibbs-Bogoliubov inequality. Such a system can be considered as an approximation of the natural material azurite, Cu3(CO3)2(OH)2. For values of exchange parameters, which are taken from experimental results, we study the thermodynamic properties, such as azurite specific heat and magnetic susceptibility. We also have studied the thermal entanglement properties and magnetization plateau of the distorted diamond chain model for azurite

Magnetic properties and concurrence for fluid 3He on kagome lattice

We present the results of magnetic properties and entanglement for kagome lattice using Heisenberg model with two-, and three-site exchange interactions in strong magnetic field. Kagome lattice correspond to the third layer of fluid 3He absorbed on the surface of graphite. The magnetic properties and concurrence as a measure of pairwise thermal entanglement are studied by means of variational mean-field like treatment based on Gibbs-Bogoliubov inequality. The system exhibits different magnetic behaviors, depending on the values of the exchange parameters (J2, J3). We have obtained the magnetization plateaus at low temperatures. The central theme of the paper is the comparing the entanglement and magnetic behavior for kagome lattice. We have found that in the antiferromagnetic region behaviour of the concurrence coincides with the magnetization one.Comment: Physics of Atomic Nuclei (accepted for publication) 201

Recoil Studies in the Reaction of 12-C Ions with the Enriched Isotope 118-Sn

The recoil properties of the product nuclei from the interaction of 2.2 GeV/nucleon 12-C ions from Nuclotron of the Laboratory of High Energies (LHE), Joint Institute for Nuclear Research (JINR) at Dubna with a 118-Sn target have been studied using catcher foils. The experimental data were analyzed using the mathematical formalism of the standard two-step vector model. The results for 12-C ions are compared with those for deuterons and protons. Three different Los Alamos versions of the Quark-Gluon String Model (LAQGSM) were used for comparison with our experimental data.Comment: 10 pages, 6 figures, submitted to Nucl. Phys.

Study of Bs-> \phi l^+ l^-$ Decay in a Single Universal Extra Dimension

Utilizing form factors calculated within the light-cone sum rules, we have evaluated the decay branching ratios of $B_s\to \phi\gamma$ and $B_s\to \phi \ell^+\ell^-$ in a single universal extra dimension model (UED), which is viewed as one of the alternative theories beyond the standard model (SM). For the decay $B_s \to \phi \ell^+\ell^-$, the dilepton invariant mass spectra, the forward-backward asymmetry, and double lepton polarization are also calculated. For each case, we compared the obtained results with predictions of the SM. In lower values of the compactification factor 1/R, the only parameter in this model, we see the considerable discrepancy between the UED and SM models. However, when 1/R increases, the results of UED tend to diminish and at $1/R = 1000 \mathrm{GeV}$, two models have approximately the same predictions. Compared with data from CDF of $B_s \to \phi \mu^+ \mu^-$, the 1/R tends to be larger than $350 \mathrm{GeV}$. We also note that the zero crossing point of the forward-backward asymmetry is become smaller, which will be an important plat to prob the contribution from the extra dimension model. The results obtained in this work will be very useful in searching new physics beyond SM. Moreover, the order of magnitude for branching ratios shows a possibility to study these channels at the Large Hadron Collider (LHC), CDF and the future super-B factory.Comment: 13 pages, 16 figure

Search for Doubly-Charged Higgs Boson Production at HERA

A search for the single production of doubly-charged Higgs bosons H^{\pm \pm} in ep collisions is presented. The signal is searched for via the Higgs decays into a high mass pair of same charge leptons, one of them being an electron. The analysis uses up to 118 pb^{-1} of ep data collected by the H1 experiment at HERA. No evidence for doubly-charged Higgs production is observed and mass dependent upper limits are derived on the Yukawa couplings h_{el} of the Higgs boson to an electron-lepton pair. Assuming that the doubly-charged Higgs only decays into an electron and a muon via a coupling of electromagnetic strength h_{e \mu} = \sqrt{4 \pi \alpha_{em}} = 0.3, a lower limit of 141 GeV on the H^{\pm\pm} mass is obtained at the 95% confidence level. For a doubly-charged Higgs decaying only into an electron and a tau and a coupling h_{e\tau} = 0.3, masses below 112 GeV are ruled out.Comment: 15 pages, 3 figures, 1 tabl

Forward pi^0 Production and Associated Transverse Energy Flow in Deep-Inelastic Scattering at HERA

Deep-inelastic positron-proton interactions at low values of Bjorken-x down to x \approx 4.10^-5 which give rise to high transverse momentum pi^0 mesons are studied with the H1 experiment at HERA. The inclusive cross section for pi^0 mesons produced at small angles with respect to the proton remnant (the forward region) is presented as a function of the transverse momentum and energy of the pi^0 and of the four-momentum transfer Q^2 and Bjorken-x. Measurements are also presented of the transverse energy flow in events containing a forward pi^0 meson. Hadronic final state calculations based on QCD models implementing different parton evolution schemes are confronted with the data.Comment: 27 pages, 8 figures and 3 table

New Physics in b -> s mu+ mu-: CP-Conserving Observables

We perform a comprehensive study of the impact of new-physics operators with different Lorentz structures on decays involving the b -> s mu+ mu- transition. We examine the effects of new vector-axial vector (VA), scalar-pseudoscalar (SP) and tensor (T) interactions on the differential branching ratios and forward-backward asymmetries (A_{FB}'s) of Bsbar -> mu+ mu-, Bdbar -> Xs mu+ mu-, Bsbar -> mu+ mu- gamma, Bdbar -> Kbar mu+ mu-, and Bdbar -> K* mu+ mu-, taking the new-physics couplings to be real. In Bdbar -> K* mu+ mu-, we further explore the polarization fraction f_L, the angular asymmetry A_T^{(2)}, and the longitudinal-transverse asymmetry A_{LT}. We identify the Lorentz structures that would significantly impact these observables, providing analytical arguments in terms of the contributions from the individual operators and their interference terms. In particular, we show that while the new VA operators can significantly enhance most of the asymmetries beyond the Standard Model predictions, the SP and T operators can do this only for A_{FB} in Bdbar -> Kbar mu+ mu-.Comment: 54 pages, JHEP format, 45 figures (included). 5/6/2013: typos in K* mu mu angular coefficients corrected, typos in Eq. (D.12) corrected, added a missing term in I3LT in Eq. (D.16). Numerical analysis unchange