62 research outputs found
Multi-Dimensional Cosmology and GUP
We consider a multidimensional cosmological model with FRW type metric having
4-dimensional space-time and -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 decays in the QCD sum rules
Rare exclusive 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 with phase about
, which is consistent with the of the CKM and the
mixing parameter , we obtain that for both ()
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( 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
to 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 and Decays in the Universal Extra Dimension
We investigate the influence of the universal extra dimension on the
branching ratio in the decay. Taking GeV with one universal extra spatial dimension, which is
consistent with the experimental data for , ) and the electroweak precision tests, we obtain
that for both () 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( via its indirect manifestations in loop diagrams.Comment: 17 pages, 8 figure
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