Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Isolating New Physics Effects from Hadronic Form Factor Uncertainties in B\to K^* \ell^+\ell^-  [PDF]
Diganta Das,Rahul Sinha
Physics , 2012,
Abstract: The discovery of New Physics, using weak decays of mesons is difficult due to intractable strong interaction effects needed to describe it. We show how the multitude of "related observables" obtained from B\to K^* \ell^+\ell^-, can provide many new "clean tests" of the Standard Model. The hallmark of these tests is that several of them are independent of the unknown form factors required to describe the decay using heavy quark effective theory. We derive a relation between observables that is free of form factors and Wilson coefficients, the violation of which will be an unambiguous signal of New Physics. We also derive other relations between observables and form factors that are independent of Wilson coefficients and enable verification of hadronic estimates. We find that the allowed parameter space for observables is very tightly constrained in Standard Model, thereby providing clean signals of New Physics. The relations derived will provide unambiguous signals of New Physics if it contributes to these decays.
On B -> V l l at small dilepton invariant mass, power corrections, and new physics  [PDF]
Sebastian J?ger,Jorge Martin Camalich
Physics , 2012, DOI: 10.1007/JHEP05(2013)043
Abstract: We investigate rare semileptonic \bar B -> \bar K^* l^+ l^- decays, providing a comprehensive treatment of theoretical uncertainties in the low-q^2 region as needed for interpreting current and future LHCb and B-factory data in terms of the new physics search. We go beyond the usual focus on form-factor uncertainties, paying proper attention to non-factorizable terms. A central point is the systematic exploitation of the V-A structure of SM weak interactions, which leads to the suppression of two helicity amplitudes and some of the angular coefficients. We review how this works at the level of (helicity) form factors, and show that the hierarchies extend to non-factorizable terms. For virtual charm effects, we give an argument for it in terms of light-cone QCD sum rules that continues to hold at the level of "long-distance" Lambda_QCD^2/m_c^2 power corrections, reducing an important source of theoretical uncertainty in any \bar B, \bar B_s -> V l^+ l^- (or \bar B -> V gamma) decay. The contributions of the remaining hadronic weak Hamiltonian respect a similar hierarchy. We employ a resonance model to preclude (in the \bar B -> \bar K^* case) large long-distance corrections to this. A phenomenological part pays particular attention to the region of lowest dilepton mass, 4 m_l^2 <= q^2 <= 2 GeV^2. Two observables remain theoretically clean, implying a (theoretical) sensitivity to the real (imaginary) part of the "right-handed" Wilson coefficient C_7' to 10% (1%) of C_7^SM, both in the muonic and the electronic mode. We also show that there are two near-exact relations between angular coefficients, even in the presence of new physics and when lepton masses are not neglected.
Addressing Hadronic Uncertainties in Extractions of $φ_s$  [PDF]
Robert Knegjens
Physics , 2014,
Abstract: In light of recent LHC results for the extraction of the $B_s$ mixing phase $\phi_s$, we can already conclude that if New Physics (NP) is present in this observable, it is hiding pretty well. Thus, as our hunt continues, we must be weary not to confuse NP for penguin effects, or vice versa. In this talk the progress made towards addressing hadronic uncertainties in extractions of $\phi_s$ from $B_s\to J/\psi \phi$ is reviewed, and the nature of the scalar $f_0(980)$ state, which plays a dominant role in the extraction of $\phi_s$ from the $B_s\to J/\psi \pi^+\pi^-$ decay, is discussed.
Hadronic Physics  [PDF]
Ulf-G. Mei?ner
Physics , 2000,
Abstract: I review the novel results and developments presented at the Third Workshop on Physics and Detectors for DA$\Phi$NE that deal with hadronic physics. Topics discussed include: the scalar quark condensate, kaon decays, the sector of scalar and vector mesons, kaon-nucleon scattering, pion- and kaon-nucleon sigma terms, and strange nuclear physics.
Quantifying and Reducing Model-Form Uncertainties in Reynolds-Averaged Navier-Stokes Simulations: An Open-Box, Physics-Based, Bayesian Approach  [PDF]
H. Xiao,J. -L. Wu,J. -X. Wang,R. Sun,C. J. Roy
Physics , 2015,
Abstract: Despite their well-known limitations, Reynolds-Averaged Navier-Stokes (RANS) models are still the workhorse tools for turbulent flow simulations in today's engineering application. For many practical flows, the turbulence models are by far the largest source of uncertainty. In this work we develop an open-box, physics-informed Bayesian framework for quantifying model-form uncertainties in RANS simulations. Uncertainties are introduced directly to the Reynolds stresses and are represented with compact parameterization accounting for empirical prior knowledge and physical constraints (e.g., realizability, smoothness, and symmetry). An iterative ensemble Kalman method is used to assimilate the prior knowledge and observation data in a Bayesian framework, and to propagate them to posterior distributions of velocities and other Quantities of Interest (QoIs). We use two representative cases, the flow over periodic hills and the flow in a square duct, to evaluate the performance of the proposed framework. Simulation results suggest that, even with very sparse observations, the posterior mean velocities and other QoIs have significantly better agreement with the benchmark data compared to the baseline results. At most locations the posterior distribution adequately captures the true model error within the developed model form uncertainty bounds. The framework is a major improvement over existing black-box, physics-neutral methods for model-form uncertainty quantification, and has potential implications in many fields in which the model uncertainty comes from unresolved physical processes. A notable example is climate modeling, where high-consequence decisions are made based on predictions (e.g., projected temperature rise) with major uncertainties originating from closure models that are used to account for unresolved or unknown physics including radiation, cloud, and boundary layer processes.
Introduction to Hadronic B Physics  [PDF]
Adam F. Falk
Physics , 1998,
Abstract: An overview of the theory of B physics is given, with an emphasis on issues in the strong interactions and hadronic physics. This article is taken from an introductory chapter of The BaBar Physics Book - Physics at an Asymmetric B Factory, SLAC Report SLAC-R-504. It is written at the level of a basic survey aimed at the experimental community.
Measurement of |V_cb| and the form-factor slope for Bbar -> D l^- nubar_l decays on the recoil of fully reconstructed B mesons  [PDF]
The BABAR Collaboration,B. Aubert
Physics , 2008,
Abstract: We present a measurement of the CKM matrix element |V_cb| and the form-factor slope rho^2 for Bbar -> D l^- nubar_l decays based on 417 fb-1 of data collected at the Upsilon(4S) resonance with the BaBar detector. The semileptonic decays are selected in BBar events in which the hadronic decay of the second B meson is fully reconstructed. From the measured differential decay rate of the signal decay we determine G(1) |V_cb|= (43.0 +/- 1.9 +/- 1.4) x 10^-3, rho^2 = 1.20 +/- 0.09 +/- 0.04, where G(1) is the hadronic form factor at the point of zero recoil. Using a lattice calculation for G(1) we extract |V_cb|= (39.8 +/- 1.8 +/- 1.3 +/- 0.9) x 10^-3, where the stated errors refer to the statistical, systematic, and form factor uncertainties. We also present a measurement of the exclusive branching fractions, BF(B^- -> D^0 l^- nubar_l) = (2.31 +/- 0.08 +/- 0.07)% and BF (B0bar -> D^+ l^- nubar_l)=(2.23 +/- 0.11 +/- 0.08)%.
Key Issues in Hadronic Physics  [PDF]
Simon Capstick,Steven Dytman,Roy Holt,Xiangdong Ji,John Negele,Eric Swanson
Physics , 2000,
Abstract: A group of fifty physicists met in Duck, NC, Nov. 6-9 to discuss the current status and future goals of hadronic physics. The main purpose of the meeting was to define the field by identifying its key issues, challenges, and opportunities. The conclusions, incorporating considerable input from the community at large, are presented in this white paper.
A Vision of Hadronic Physics  [PDF]
A. W. Thomas
Physics , 2014, DOI: 10.1051/epjconf/20147301018
Abstract: We present a vision for the next decade of hadron physics in which the central question being addressed is how one might win new physical insight into the way hadronic systems work. The topics addressed include the relevance of model building, the role of spontaneously broken chiral symmetry, spectroscopy, form factors and physics in the deep inelastic regime.
Towards Precise Determinations of the CKM Matrix without Hadronic Uncertainties  [PDF]
A. J. Buras
Physics , 1994,
Abstract: We illustrate how the measurements of the CP asymmetries in $B^0_{d,s}$-decays together with a measurement of $Br(K_L\to \pi^\circ\nu\bar\nu)$ or $Br(K^+\to \pi^+\nu\bar\nu)$ and the known value of $\mid V_{us}\mid $ can determine all elements of the Cabibbo-Kobayashi-Maskawa matrix essentially without any hadronic uncertainties. An analysis using the ratio $x_d/x_s$ of $B_d-\bar B_d$ to $B_s-\bar B_s$ mixings is also presented.
Page 1 /100
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.