35,376 research outputs found

    A proposal for testing Quantum Gravity in the lab

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    Attempts to formulate a quantum theory of gravitation are collectively known as {\it quantum gravity}. Various approaches to quantum gravity such as string theory and loop quantum gravity, as well as black hole physics and doubly special relativity theories predict a minimum measurable length, or a maximum observable momentum, and related modifications of the Heisenberg Uncertainty Principle to a so-called generalized uncertainty principle (GUP). We have proposed a GUP consistent with string theory, black hole physics and doubly special relativity theories and have showed that this modifies all quantum mechanical Hamiltonians. When applied to an elementary particle, it suggests that the space that confines it must be quantized, and in fact that all measurable lengths are quantized in units of a fundamental length (which can be the Planck length). On the one hand, this may signal the breakdown of the spacetime continuum picture near that scale, and on the other hand, it can predict an upper bound on the quantum gravity parameter in the GUP, from current observations. Furthermore, such fundamental discreteness of space may have observable consequences at length scales much larger than the Planck scale. Because this influences all the quantum Hamiltonians in an universal way, it predicts quantum gravity corrections to various quantum phenomena. Therefore, in the present work we compute these corrections to the Lamb shift, simple harmonic oscillator, Landau levels, and the tunneling current in a scanning tunneling microscope.Comment: v1: 10 pages, REVTeX 4, no figures; v2: minor typos corrected and a reference added. arXiv admin note: has substantial overlap with arXiv:0906.5396 , published in a different journa

    The Impact of Financial Determinants On Bank Deposits Using ARDL Model

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    The purpose of this research is to quantify the impact of macroeconomic factors on Jordanian bank deposits in the context of the CoVD-19 epidemic. The annual data are collected between 1980 and 2020. The novel Autoregressive distributed lag (ARDL) model is suggested to evaluate the link between bank deposits and macroeconomic factors. The findings of Grangers causality test indicate that there is a one-way causal link between deposits and macroeconomic factors. Moreover, the study shows no causal link between financial shocks and bank deposits. In addition, the border test investigates the existence of a long-term equilibrium between variables. To attain long-term equilibrium, the imbalance in the short-term equilibrium is adjusted at a rate of 11.6%. Based on the Theil test, the new model is suitable for econometric difficulties and predictability

    Final state rescattering as a contribution to BργB \to \rho \gamma

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    We provide a new estimate of the long-distance component to the radiative transition BργB \to \rho \gamma. Our mechanism involves the soft-scattering of on-shell hadronic products of nonleptonic BB decay, as in the chain BρρργB \to \rho\rho \to \rho\gamma. We employ a phenomenological fit to scattering data to estimate the effect. The specific intermediate states considered here modify the BργB \to \rho \gamma decay rate at roughly the 585 \to 8% level, although the underlying effect has the potential to be larger. Contrary to other mechanisms of long distance physics which have been discussed in the literature, this yields a non-negligible modification of the B0ρ0γB^0 \to \rho^0 \gamma channel and hence will provide an uncertainty in the extraction of VtdV_{td}. This mechanism also affects the isospin relation between the rates for BργB^- \to \rho^-\gamma and B0ρ0γB^0 \to \rho^0 \gamma and may generate CP asymmetries at experimentally observable levels.Comment: 15 pages, RevTex, 3 figure

    Supersymmetric Effects on Isospin Symmetry Breaking and Direct CP Violation in BργB \to \rho \gamma

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    We argue that one can search for physics beyond the standard model through measurements of the isospin-violating quantity Δ0Γ(Bργ)/2Γ(B0ρ0γ)1\Delta^{-0} \equiv \Gamma(B^- \to \rho^- \gamma)/2\Gamma(B^0 \to \rho^0 \gamma)-1, its charge conjugate Δ+0\Delta^{+0}, and direct CP violation in the partial decay rates of B±ρ±γB^\pm \to \rho^\pm \gamma. We illustrate this by working out theoretical profiles of the charge-conjugate averaged ratio Δ12(Δ+0+Δ0)\Delta \equiv {1 \over 2}(\Delta^{+0} +\Delta^{-0}) and the CP asymmetry ACP(B±ρ±γ)A_{CP}(B^\pm \to \rho^\pm \gamma) in the standard model and in some variants of the minimal supersymmetric standard model. We find that chargino contributions in the large tanβ\tan \beta region may modify the magnitudes and flip the signs of Δ\Delta and ACP(B±ρ±γ)A_{CP}(B^\pm \to \rho^\pm \gamma) compared to their standard-model values, providing an unmistakeable signature of supersymmetry.Comment: 10 pages, 7 figures (requires graphicx

    Ultrafast effective multi-level atom method for primordial hydrogen recombination

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    Cosmological hydrogen recombination has recently been the subject of renewed attention because of its importance for predicting the power spectrum of cosmic microwave background anisotropies. It has become clear that it is necessary to account for a large number n >~ 100 of energy shells of the hydrogen atom, separately following the angular momentum substates in order to obtain sufficiently accurate recombination histories. However, the multi-level atom codes that follow the populations of all these levels are computationally expensive, limiting recent analyses to only a few points in parameter space. In this paper, we present a new method for solving the multi-level atom recombination problem, which splits the problem into a computationally expensive atomic physics component that is independent of the cosmology, and an ultrafast cosmological evolution component. The atomic physics component follows the network of bound-bound and bound-free transitions among excited states and computes the resulting effective transition rates for the small set of "interface" states radiatively connected to the ground state. The cosmological evolution component only follows the populations of the interface states. By pre-tabulating the effective rates, we can reduce the recurring cost of multi-level atom calculations by more than 5 orders of magnitude. The resulting code is fast enough for inclusion in Markov Chain Monte Carlo parameter estimation algorithms. It does not yet include the radiative transfer or high-n two-photon processes considered in some recent papers. Further work on analytic treatments for these effects will be required in order to produce a recombination code usable for Planck data analysis.Comment: Version accepted by Phys. Rev. D. Proof of equivalence of effective and standard MLA methods moved to the main text. Some rewording

    Potential Models for Radiative Rare B Decays

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    We compute the branching ratios for the radiative rare decays of B into K-Meson states and compare them to the experimentally determined branching ratio for inclusive decay b -> s gamma using non relativistic quark model, and form factor definitions consistent with HQET covariant trace formalism. Such calculations necessarily involve a potential model. In order to test the sensitivity of calculations to potential models we have used three different potentials, namely linear potential, screening confining potential and heavy quark potential as it stands in QCD.We find the branching ratios relative to the inclusive b ->s gamma decay to be (16.07\pm 5.2)% for B -> K^* (892)gamma and (7.25\pm 3.2)% for B -> K_2^* (1430)gamma for linear potential. In the case of the screening confining potential these values are (19.75\pm 5.3)% and (4.74\pm 1.2)% while those for the heavy quark potential are (11.18\pm 4.6)% and (5.09\pm 2.7)% respectively. All these values are consistent with the corresponding present CLEO experimental values: (16.25\pm 1.21)% and (5.93\pm 0.46)%.Comment: RevTeX, 6 pages, 1 eps figur

    Radiative and Semileptonic B Decays Involving Higher K-Resonances in the Final States

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    We study the radiative and semileptonic B decays involving a spin-JJ resonant KJ()K_J^{(*)} with parity (1)J(-1)^J for KJK_J^* and (1)J+1(-1)^{J+1} for KJK_J in the final state. Using the large energy effective theory (LEET) techniques, we formulate BKJ()B \to K_J^{(*)} transition form factors in the large recoil region in terms of two independent LEET functions ζKJ()\zeta_\perp^{K_J^{(*)}} and ζKJ()\zeta_\parallel^{K_J^{(*)}}, the values of which at zero momentum transfer are estimated in the BSW model. According to the QCD counting rules, ζ,KJ()\zeta_{\perp,\parallel}^{K_J^{(*)}} exhibit a dipole dependence in q2q^2. We predict the decay rates for BKJ()γB \to K_J^{(*)} \gamma, BKJ()+B \to K_J^{(*)} \ell^+ \ell^- and BKJ()ννˉB \to K_J^{(*)}\nu \bar{\nu}. The branching fractions for these decays with higher KK-resonances in the final state are suppressed due to the smaller phase spaces and the smaller values of ζ,KJ()\zeta^{K_J^{(*)}}_{\perp,\parallel}. Furthermore, if the spin of KJ()K_J^{(*)} becomes larger, the branching fractions will be further suppressed due to the smaller Clebsch-Gordan coefficients defined by the polarization tensors of the KJ()K_J^{(*)}. We also calculate the forward backward asymmetry of the BKJ()+B \to K_J^{(*)} \ell^+ \ell^- decay, for which the zero is highly insensitive to the KK-resonances in the LEET parametrization.Comment: 27 pages, 4 figures, 7 tables;contents and figures corrected, title and references revise
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