We elaborate on various aspects of our top-down celestial holographic duality wherein the semiclassical bulk spacetime is a 4d asymptotically flat, self-dual Kähler geometry known as Burns space. The bulk theory includes an open string sector comprising a 4d WZW model and a closed string sector called “Mabuchi gravity” capturing fluctuations of the Kähler potential. Starting with the type I topological B-model on the twistor space of flat space, we obtain the twistor space of Burns space from the backreaction of a stack of $\textit{N}$ coincident D1 branes, while the chiral algebra is obtained from (a twist of) the brane worldvolume theory. One striking consequence of this duality is that all loop-level scattering amplitudes of the theory on Burns space can be expressed as correlation functions of an explicit 2d chiral algebra.

Canada

Kevin Costello

United States

Natalie Paquette

Atul Sharma

Burns space and holography

We present a model for the <math><mi>J</mi><mo>/</mo><mi>ψ</mi><mspace width="0.2em"></mspace><mi>Λ</mi></math> spectrum in <math><msup><mrow><mi>B</mi></mrow><mrow><mo>−</mo></mrow></msup><mo>→</mo><mi>J</mi><mo>/</mo><mi>ψ</mi><mspace width="0.2em"></mspace><mi>Λ</mi><mspace width="0.2em"></mspace><mover><mrow><mi>p</mi></mrow><mrow><mo>¯</mo></mrow></mover></math> decays, including the <math><msubsup><mrow><mi>P</mi></mrow><mrow><mi>ψ</mi><mi>s</mi></mrow><mrow><mi>Λ</mi></mrow></msubsup><mo>(</mo><mn>4338</mn><mo>)</mo></math> baryon recently observed by the LHCb collaboration. We assume production via triangle diagrams which couple to the final state via non-perturbative interactions which are constrained by heavy-quark and <math><mi>S</mi><msub><mrow><mi>U</mi></mrow><mrow><mn>3</mn></mrow></msub></math>-flavor symmetry. The bulk of the distribution is described by a triangle diagram with a color-favored electroweak vertex, while the sharp <math><msubsup><mrow><mi>P</mi></mrow><mrow><mi>ψ</mi><mi>s</mi></mrow><mrow><mi>Λ</mi></mrow></msubsup><mo>(</mo><mn>4338</mn><mo>)</mo></math> enhancement is due to the triangle singularity in another diagram featuring a <math><mn>1</mn><mo>/</mo><msup><mrow><mn>2</mn></mrow><mrow><mo>−</mo></mrow></msup></math> baryon consistent with <math><msub><mrow><mi>Σ</mi></mrow><mrow><mi>c</mi></mrow></msub><mo>(</mo><mn>2800</mn><mo>)</mo></math>. We predict a comparable <math><msubsup><mrow><mi>P</mi></mrow><mrow><mi>ψ</mi><mi>s</mi></mrow><mrow><mi>Λ</mi></mrow></msubsup><mo>(</mo><mn>4338</mn><mo>)</mo></math> signal in <math><msub><mrow><mi>η</mi></mrow><mrow><mi>c</mi></mrow></msub><mspace width="0.2em"></mspace><mi>Λ</mi></math>, and anticipate possible large isospin mixing effects through decays to <math><mi>J</mi><mo>/</mo><mi>ψ</mi><mspace width="0.2em"></mspace><msup><mrow><mi>Σ</mi></mrow><mrow><mn>0</mn></mrow></msup></math> and <math><msub><mrow><mi>η</mi></mrow><mrow><mi>c</mi></mrow></msub><mspace width="0.2em"></mspace><msup><mrow><mi>Σ</mi></mrow><mrow><mn>0</mn></mrow></msup></math>.

United Kingdom

T.J. Burns

E.S. Swanson

The LHCb state As a Triangle Singularity

We examine whether the LHCb vector <math><mi>u</mi><mi>d</mi><mover><mrow><mi>c</mi></mrow><mrow><mo>¯</mo></mrow></mover><mover><mrow><mi>s</mi></mrow><mrow><mo>¯</mo></mrow></mover></math> state <math><mi>X</mi><mo>(</mo><mn>2900</mn><mo>)</mo></math> can be interpreted as a kinematical cusp effect arising from <math><msup><mrow><mover><mrow><mi>D</mi></mrow><mrow><mo>¯</mo></mrow></mover></mrow><mrow><mo>⁎</mo></mrow></msup><msup><mrow><mi>K</mi></mrow><mrow><mo>⁎</mo></mrow></msup></math> and <math><msub><mrow><mover><mrow><mi>D</mi></mrow><mrow><mo>¯</mo></mrow></mover></mrow><mrow><mn>1</mn></mrow></msub><msup><mrow><mi>K</mi></mrow><mrow><mo>(</mo><mo>⁎</mo><mo>)</mo></mrow></msup></math> interactions. The production amplitude is modelled as a triangle diagram with hadronic final state interactions. A satisfactory fit to the Dalitz plot projection is obtained that leverages the singularities of the production diagram without the need for <math><mover><mrow><mi>D</mi></mrow><mrow><mo>¯</mo></mrow></mover><mi>K</mi></math> resonances. A somewhat better fit is obtained if the final state interactions are strong enough to generate resonances, although the evidence in favour of this scenario is not conclusive.

Kinematical cusp and resonance interpretations of the (2900)

A variety of options for interpreting the DØ state, X(5568) , are examined. We find that threshold, cusp, molecular, and tetraquark models are all unfavoured. Several experimental tests for unravelling the nature of the signal are suggested.