Does gravity act faster than the speed of light, and can this be measured?

Professor Aida El-Khadra received her PhD. in 1989 from the University of California, Los Angeles, after receiving her diplom from Freie Universitaet, Berlin, Germany. She held postdoctoral research appointments at Brookhaven National Laboratory, Fermi National Accelerator Laboratory, and the Ohio State Univerity before joining the Illinois faculty in 1995. El-Khadra is a fellow of the American Physical Society, a recipient of the Department of Energy's Outstanding Junior Investigator Award, and a Sloan foundation fellow. In addition to a number of other research and teaching awards she was also recently named a Fermilab Distinguished Scholar. El-Khadra is currently serving on the APS Division of Particles and Fields (DPF) executive committee.

Prof. El-Khadra's area of research is theoretical particle physics. Her research focuses on the application of lattice Quantum Chromodynamics (also called the strong interactions) to phenomenologically interesting processes in flavor physics, which are relevant to the experimental effort at the so-called intensity frontier. She is a leader of one of the most successful collaborations working in Lattice Field Theory in the world, the Fermilab Lattice collaboration. Select highlights include the first quantitative determination of the the strong coupling from lattice QCD, a new formulation of heavy quarks on the lattice that is the foundation of many important, phenomenologically relevant lattice calculations, for example, **predictions** of the *D* and *D _{s}* meson decay constants, predictions of the shape of the semileptonic

**Phenomenology with Lattice QCD**

Quantum chromodynamics (QCD), the theory of the strong interactions, is amenable to perturbative calculations only at high energies. A quantitative understanding of the low-energy behavior of QCD, like the interactions of quarks inside hadrons, requires nonperturbative methods. Lattice field theory offers a systematic approach to solving QCD nonperturbatively. The space-time continuum is replaced by a discrete lattice. Part of our research is concerned with improvements in the formulation of lattice QCD. Other projects deal with applications of lattice QCD to phenomenologically interesting processes that test the standard model of particle physics and potentially yield insight into new physics scenarios.

- Collins Award for Innovative Teaching, COE
- Fellow, American Physical Society
- Center for Advanced Study Associate
- Frontier Fellow, Fermilab
- Beckman Fellow in the Center for Advanced Study
- Xerox for Faculty Research Award
- A. P. Sloan Foundation Fellow
- DOE Outstanding Junior Investigator Award

- A. Bazavov et al [Fermilab Lattice and MILC Collaborations]. B0(s)-mixing matrix elements from lattice QCD for the Standard Model and beyond. arXiv:1602.03560 [hep-lat]. To appear in Physical Review D (2016).
- Daping Du, A.X. El-Khadra, Steven Gottlieb, A.S. Kronfeld, J. Laiho, E. Lunghi, R.S. Van de Water, Ran Zhou. Phenomenology of Semileptonic B-Meson Decays with Form Factors from Lattice QCD. arXiv:1510.02349 [hep-ph]. Physical Review D 93, no. 3, 034005 (2016).
- J.A. Bailey et al. B -> Kl+l- decay form factors from three-flavor lattice QCD. arXiv:1509.06235 [hep-lat]. Physical Review D 93, no. 2, 025026 (2016).
- J.A. Bailey et al. B -> pi ll Form Factors for New-Physics Searches from Lattice QCD. arXiv:1507.01618 [hep-ph]. Phys. Rev. Lett. 115 (2015) 15, 152002.
- J.A. Bailey et al. |Vub| from B -> pi decays and (2+1)-flavor lattice QCD. arXiv:1503.07839 [hep-lat]. Phys.Rev. D92 (2015) 1, 014024.
- J. Bailey et al. The B -> D form factors at nonzero recoil and |Vcb| from 2+1-flavor lattice QCD. arXiv:1503.07237 [hep-lat]. Phys.Rev. D92 (2015) 3, 034506.
- A. Bazavov et al. Charmed and light pseudoscalar meson decay constants from four-flavor lattice QCD with physical light quarks. arXiv:1407.3772 [hep-lat]. Phys.Rev. D90 (2014) 074509.
- J. Bailey, et al. Update of |Vcb| from the B -> D* l nu form factor at zero recoil with three-flavor lattice QCD. arXiv:1403.0635 [hep-lat]. Phys. Rev. D89 (2014) 11, 114504.
- A. Bazavov, et al. Determination of |Vus| from a lattice-QCD calculation of the K -> pi l nu semileptonic form factor with physical quark masses. Phys.Rev.Lett. 112, 112001 (2014).
- S. Aoki, et al. Review of lattice results concerning low energy particle physics. arXiv:1310.8555 [hep-lat]. Eur.Phys.J. C74 (2014) 2890.
- A. Bazavov, et al. Kaon semileptonic vector form factor and determination of |V_{us}| using staggered fermions. Phys. Rev. D 87, 073012. (2013)
- Jon A. Bailey, et al. Refining new-physics searches in B->D tau nu decay with lattice QCD. Phys. Rev. Lett. 109, 071802 (2012).
- A. Bazavov, et al. Neutral B-meson mixing from three-flavor lattice QCD: Determination of the SU(3)-breaking ratio xi. Phys. Rev. D86 034503 (2012).
- Jon A. Bailey, et al. Bs -> Ds/B->D Semileptonic Form-Factor Ratios and Their Application to BR(B0s -> mu+ mu-). Phys. Rev. D85, 114502 (2012).
- A. Bazavov, et al. B- and D-meson decay constants from three-flavor lattice QCD. Phys. Rev. D85, 114506 (2012).
- C. Bernard, et al. Tuning Fermilab Heavy Quarks in 2+1 Flavor Lattice QCD with Application to Hyperfine Splittings. Phys. Rev. D83, 034503 (2011).
- T. Burch, et al. Quarkonium mass splittings in three-flavor lattice QCD. Phys. Rev. D 81, 034508 (2010).
- C. Bernard et al. Visualization of semileptonic form factors from lattice QCD. Phys. Rev. D 80, 034026 (2009).
- J. Bailey, et al. The B -> pi l nu semileptonic form factor from three-flavor lattice QCD: A model-independent determination of |V(ub)|. Phys. Rev. D 79, 054507 (2009).
- C. Bernard, et al. The Anti-B ---> D* l anti-nu form factor at zero recoil from three-flavor lattice QCD: A Model independent determination of |V(cb)|. Phys. Rev. D
**79**, 014506 (2009). - A. X. El-Khadra, A. Kronfeld, and P. Mackenzie. Massive quarks in lattice QCD. Phys. Rev. D 3933-3957 (1997).
- T. Primer , C. Bernard, C. DeTar, A. El-Khadra, E. Gámiz, J. Komijani, A. Kronfeld, J. Simone, D. Toussaint, R. Van de Water. [Fermilab Lattice and MILC Collaborations]. D-meson semileptonic form factors at zero momentum transfer in (2+1+1)-flavor lattice QCD. arXiv:1511.04000 [hep-lat].
- A. Bazavov et al. [MILC and Fermilab Lattice Collaborations]. Decay constants fB and fBs from HISQ simulations. PoS LATTICE2015 (2015) 331. arXiv:1511.02294 [hep-lat].
- C. Bouchard et al. Neutral B-meson mixing parameters in and beyond the SM with 2+1 flavor lattice QCD. arXiv:1412.5097 [hep-lat]. PoS LATTICE2014 (2014) 378.
- C.C. Chang, C.M. Bouchard, A.X. El-Khadra, E.D. Freeland, E. Gamiz, A.S. Kronfeld, J. Laiho, R.S. Van de Water. Update on a short-distance D^0-meson mixing calculation with Nf=2+1 flavors. arXiv:1411.6086 [hep-lat]. PoS LATTICE2014 (2014) 384.
- J. Bailey et al. $B \to \pi \ell \nu$ semileptonic form factors from unquenched lattice QCD and determination of |Vub|. arXiv:1411.6038 [hep-lat]. PoS LATTICE2014 (2014) 385.
- A. Bazavov at al. Charmed and light pseudoscalar meson decay constants from HISQ simulations. arXiv:1411.2667 [hep-lat]. PoS LATTICE2014 (2014) 382.
- T. Primer, D. Toussaint, A. El-Khadra, E. Gamiz, J. Simone. Kaon and D meson semileptonic form factors from lattice QCD. arXiv:1411.1651 [hep-lat]. PoS LATTICE2014 (2014) 374.
- A. Bazavov, et al. The $D_s$, $D^+$, $B_s$ and $B$ decay constants from $2+1$ flavor lattice QCD. arXiv:1403.6796 [hep-lat]. PoS LATTICE2013 (2014) 394
- Aida X. El-Khadra. Quark Flavor Physics Review. arXiv:1403.5252 [hep-lat]. PoS LATTICE 2013 (2014) 001.
- Yuzhi Liu, et al. Heavy-meson semileptonic decays for the Standard Model and beyond. arXiv:1312.3197 [hep-lat]. PoS LATTICE2013 (2013) 386.
- S.W. Qiu, J. Laiho, C. DeTar, A. Kronfeld, R.S. Van de Water, A. El-Khadra. Semileptonic decays $B\to D \ell \nu$ at nonzero recoil. arXiv:1312.0155 [hep-lat]. PoS LATTICE2013 (2014) 385.
- A. Bazavov, et al. Charmed and strange pseudoscalar meson decay constants from HISQ simulations. arXiv:1312.0149 [hep-lat]. PoS LATTICE2013 (2014) 405.
- E. Gamiz et al. K semileptonic form factor with HISQ fermions at the physical point. arXiv:1311.7264 [hep-lat]. PoS LATTICE2013 (2013) 395.
- C.C. Chang, et al. Matrix Elements for $D$- and $B$-Mixing from 2+1 Flavor Lattice QCD. arXiv:1311.6820 [hep-lat].
- Daping Du, et al. $B\to\pi\ell\nu$ and $B\to\pi\ell^+\ell^-$ semileptonic form factors from unquenched lattice QCD. PoS LATTICE2013 (2013) 383. arXiv:1311.6552 [hep-lat].
- E.D. Freeland, et al. Neutral B mixing from 2+1 flavor lattice QCD. 30th International Symposium on Lattice Field Theory (Lattice 2012). PoS LATTICE2012 (2012) 158 [arXiv:1212.5470].
- A. Bazavov, et al. Two-Point Correlator Fits on HISQ Ensembles. 30th International Symposium on Lattice Field Theory (Lattice 2012). PoS LATTICE2012 (2012) 158 [arXiv:1212.0613].
- Jon A. Bailey, et al. Charm semileptonic decays and |V_{cs(d)}| from heavy clover quarks and 2+1 flavor asqtad staggered ensembles. 30th International Symposium on Lattice Field Theory (Lattice 2012). PoS LATTICE2012 (2012) 272 [arXiv:1211.4964].
- Ran Zhou, et al. Form factors for semi-leptonic B decays. 30th International Symposium on Lattice Field Theory (Lattice 2012). PoS LATTICE2012 (2012) 120 [arXiv:1211.1390].
- E. Gamiz, et al. Kaon semileptonic decay form factors with HISQ valence quarks. 30th International Symposium on Lattice Field Theory (Lattice 2012). PoS LATTICE2012 (2012) 113 [arXiv:1211.0751]
- A. Bazavov, et al. Pseudoscalar meson physics with four dynamical quarks. 30th International Symposium on Lattice Field Theory (Lattice 2012). PoS LATTICE2012 (2012) 159 [arXiv:1210.8431].
- C.M. Bouchard, E.D. Freeland, C. Bernard, A.X. El-Khadra, E. Gamiz, A.S. Kronfeld, J. Laiho, R.S. Van de Water. Neutral B mixing from 2+1 flavor lattice-QCD: the Standard Model and beyond. 29th International Symposium on Lattice Field Theory. PoS LATTICE2011 (2011) 274 [arXiv:1112.5642].
- E. T. Neil, et al. B and D meson decay constants from 2+1 flavor improved staggered simulations. 29th International Symposium on Lattice Field Theory. PoS LATTICE2011 (2011) 320 [arXiv:1112.3978].
- Jon A. Bailey, A. Bazavov, A. X. El-Khadra, Steven Gottlieb, R. D. Jain, A. S. Kronfeld, R. S. Van de Water, R. Zhou. D semileptonic form factors and âˆ£Vcs(d)âˆ£ from 2+1 flavor lattice QCD. 29th International Symposium on Lattice Field Theory. PoS LATTICE2011 (2011) 270 [arXiv:1111.5471].
- C. Bernard, C. M. Bouchard, A. X. El-Khadra, E. D. Freeland, E. GÃ¡miz, A. S. Kronfeld, J. Laiho, R. S. Van de Water. B Mixing in the Standard Model and Beyond: Lattice QCD. Proceedings of the 19th Particles and Nuclei International Conference (PANIC11), Cambridge, MA, U.S.A., July 2011. AIP Conf.Proc. 1441 (2012) 672-674 [arXiv:1111.2968].
- E. Gamiz, C. DeTar, A. X. El-Khadra, A. S. Kronfeld, P. B. Mackenzie, J. Simone. Calculation of K-> pi Form Factors with Nf=2+1 Flavors of Staggered Quarks. 29th International Symposium on Lattice Field Theory. PoS LATTICE2011 (2011) 281 [arXiv:1111.2021].
- Ran Zhou, et al. Form Factors for B to Kll Semileptonic Decay from Three-Flavor Lattice QCD. 29th International Symposium on Lattice Field Theory. PoS LATTICE2011 (2011) 298 [arXiv:1111.0981].
- J. Simone et al. The decay constants f(D/s), f(D+), f(B/s) and f(B) from lattice QCD. 28th International Symposium On Lattice Field Theory. PoS LATTICE2010, 317 (2010).
- C. Bouchard, A.X. El-Khadra, E.D. Freeland, E. Gamiz, A.S. Kronfeld. B^0_s and B^0 Mixing in the Standard Model and Beyond: A Progress Report. 28th International Symposium On Lattice Field Theory. PoS LATTICE2010, 299 (2010).
- J.A. Bailey et al. Semileptonic decays of K and D mesons in 2+1 flavor QCD. 28th International Symposium On Lattice Field Theory. PoS LATTICE2010, 306 (2010).
- J.A. Bailey et al. B -> D* l nu at zero recoil: an update. 28th International Symposium On Lattice Field Theory. PoS LATTICE2010, 311 (2010).

**Office**

429 Loomis Laboratory

**Phone**

217.333.5026

**Fax**

217.333.1215

**Email**

axk@illinois.edu

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