Multi-Dimensional Cosmology and GUP

We consider a multidimensional cosmological model with FRW type metric having 4-dimensional space-time and $d$-dimensional Ricci-flat internal space sectors with a higher dimensional cosmological constant. We study the classical cosmology in commutative and GUP cases and obtain the corresponding exact solutions for negative and positive cosmological constants. It is shown that for negative cosmological constant, the commutative and GUP cases result in finite size universes with smaller size and longer ages, and larger size and shorter age, respectively. For positive cosmological constant, the commutative and GUP cases result in infinite size universes having late time accelerating behavior in good agreement with current observations. The accelerating phase starts in the GUP case sooner than the commutative case. In both commutative and GUP cases, and for both negative and positive cosmological constants, the internal space is stabilized to the sub-Planck size, at least within the present age of the universe. Then, we study the quantum cosmology by deriving the Wheeler-DeWitt equation, and obtain the exact solutions in the commutative case and the perturbative solutions in GUP case, to first order in the GUP small parameter, for both negative and positive cosmological constants. It is shown that good correspondence exists between the classical and quantum solutions.Comment: 21 pages, 15 figures, minor revision, references adde

MULTI-DIMENSIONAL COSMOLOGY AND DSR–GUP

A multi-dimensional cosmology with FRW type metric having four-dimensional spacetime and d-dimensional Ricci-flat internal space is considered with a higher-dimensional cosmological constant. The classical cosmology in commutative and Doubly Special Relativity–Generalized Uncertainty Principle (DSR–GUP) contexts is studied and the corresponding exact solutions for negative and positive cosmological constants are obtained. In the positive cosmological constant case, it is shown that unlike the commutative as well as GUP cases, in DSR–GUP case both scale factors of internal and external spaces after accelerating phase will inevitably experience decelerating phase leading simultaneously to a big crunch. This demarcation from GUP originates from the difference between the GUP and DSR–GUP algebras. The important result is that unlike GUP which results in eternal acceleration, DSR–GUP at first generates acceleration but prevents the eternal acceleration at late-times and turns it into deceleration

Form factors and decay rate of Bc∗→Ds l+l−B_c^\ast \rightarrow D_{s}~l^+ l^- decays in the QCD sum rules

Rare exclusive $B_c^\ast \rightarrow D_{s}~l^+ l^-$ decays are analyzed in the framework of the three--point QCD sum rules approach. The two gluon condensate corrections to the correlation function are included and the form factors of this transition are evaluated. Using the form factors, the decay width and integrated decay rate for these decays are also calculated.Comment: 17 pages, 3 figure

Exclusive B \rar \rho \ell^+ \ell^- Decay in the Standard Model with Fourth--Generation

We investigate the influence of the fourth generation of quarks on the branching ratio, the CP-asymmetry and the polarization asymmetries in B \rar \rho \ell^+ \ell^- decay. Taking $|V_{t'd}V_{t'b}|\sim 0.001$ with phase about $10^\circ$, which is consistent with the $sin2\phi_1$ of the CKM and the $B_d$ mixing parameter $\Delta m_{B_d}$, we obtain that for both ($\mu, \tau$) channels the branching ratio is increased and the magnitude of CP-asymmetry and polarization asymmetries decreased by the mass and mixing parameters of the 4th generation of quarks . These results can serve as a good tool to search for new physics effects, precisely, to search for the fourth generation of quarks($t', b')$ via its indirect manifestations in loop diagrams.Comment: 17 pages, 7 figure

BOLA360: Near-optimal View and Bitrate Adaptation for 360-degree Video Streaming

Recent advances in omnidirectional cameras and AR/VR headsets have spurred the adoption of 360-degree videos that are widely believed to be the future of online video streaming. 360-degree videos allow users to wear a head-mounted display (HMD) and experience the video as if they are physically present in the scene. Streaming high-quality 360-degree videos at scale is an unsolved problem that is more challenging than traditional (2D) video delivery. The data rate required to stream 360-degree videos is an order of magnitude more than traditional videos. Further, the penalty for rebuffering events where the video freezes or displays a blank screen is more severe as it may cause cybersickness. We propose an online adaptive bitrate (ABR) algorithm for 360-degree videos called BOLA360 that runs inside the client's video player and orchestrates the download of video segments from the server so as to maximize the quality-of-experience (QoE) of the user. BOLA360 conserves bandwidth by downloading only those video segments that are likely to fall within the field-of-view (FOV) of the user. In addition, BOLA360 continually adapts the bitrate of the downloaded video segments so as to enable a smooth playback without rebuffering. We prove that BOLA360 is near-optimal with respect to an optimal offline algorithm that maximizes QoE. Further, we evaluate BOLA360 on a wide range of network and user head movement profiles and show that it provides $13.6\%$ to $372.5\%$ more QoE than state-of-the-art algorithms. While ABR algorithms for traditional (2D) videos have been well-studied over the last decade, our work is the first ABR algorithm for 360-degree videos with both theoretical and empirical guarantees on its performance.Comment: 25 page

Exclusive B−−>πℓ+ℓ−B --> \pi \ell^+ \ell^- and B−−>ρℓ+ℓ−B --> \rho \ell^+ \ell^- Decays in the Universal Extra Dimension

We investigate the influence of the universal extra dimension on the branching ratio in the $B \to \pi(\rho) \ell^+ \ell^-$ decay. Taking $1/R\sim \{200-1000\}$GeV with one universal extra spatial dimension, which is consistent with the experimental data for ${\cal B}(B \to X_s \gamma)$, ${\cal B}(B \to K^\ast \mu^+\mu^-$) and the electroweak precision tests, we obtain that for both ($\mu,\tau$) channels the branching ratio strongly depends on the compactification radius 1/R.Comment: 14 pages, 4 figure

Black hole thermodynamics and modified GUP consistent with doubly special relativity

We study the black hole thermodynamics and obtain the correction terms for temperature, entropy, and heat capacity of the Schwarzschild black hole, resulting from the commutation relations in the framework of {\it Modified Generalized Uncertainty Principle} suggested by {\it Doubly Special Relativity}.Comment: 13 pages, 6 figures, minor revision, references adde

Competitive Algorithms for the Online Multiple Knapsack Problem with Application to Electric Vehicle Charging

We introduce and study a general version of the fractional online knapsack problem with multiple knapsacks, heterogeneous constraints on which items can be assigned to which knapsack, and rate-limiting constraints on the assignment of items to knapsacks. This problem generalizes variations of the knapsack problem and of the one-way trading problem that have previously been treated separately, and additionally finds application to the real-time control of electric vehicle (EV) charging. We introduce a new algorithm that achieves a competitive ratio within an additive factor of one of the best achievable competitive ratios for the general problem and matches or improves upon the best-known competitive ratio for special cases in the knapsack and one-way trading literatures. Moreover, our analysis provides a novel approach to online algorithm design based on an instance-dependent primal-dual analysis that connects the identification of worst-case instances to the design of algorithms. Finally, we illustrate the proposed algorithm via trace-based experiments of EV charging

Competitive Algorithms for the Online Multiple Knapsack Problem with Application to Electric Vehicle Charging

We introduce and study a general version of the fractional online knapsack problem with multiple knapsacks, heterogeneous constraints on which items can be assigned to which knapsack, and rate-limiting constraints on the assignment of items to knapsacks. This problem generalizes variations of the knapsack problem and of the one-way trading problem that have previously been treated separately, and additionally finds application to the real-time control of electric vehicle (EV) charging. We introduce a new algorithm that achieves a competitive ratio within an additive factor of one of the best achievable competitive ratios for the general problem and matches or improves upon the best-known competitive ratio for special cases in the knapsack and one-way trading literatures. Moreover, our analysis provides a novel approach to online algorithm design based on an instance-dependent primal-dual analysis that connects the identification of worst-case instances to the design of algorithms. Finally, we illustrate the proposed algorithm via trace-based experiments of EV charging

Analysis of the B --> \pi \ell^+ \ell^- Decay in the Standard Model with Fourth Generation

We investigate the influence of the fourth generation quarks on the branching ratio and the CP-asymmetry in B -->\pi \ell^+ \ell^- decay. Taking the |V_{t'd}V_{t'b}| ~ 0.001 with phase about 10 degree, which is consistent with the sin2\phi_1 of the CKM and the B_d mixing parameter \Delta m_{B_d}, we obtain that for both muon and tau channels the branching ratio, the magnitude of CP-asymmetry and lepton polarization depict strong dependency on the 4th generation quarks mass and mixing parameters. These results can serve as a good tool to search for new physics effects, precisely, to search for the fourth generation quarks($t', b')$ via its indirect manifestations in loop diagrams.Comment: 17 pages, 8 figure