More Like this

1. Chaotic scattering of highly excited strings

   https://doi.org/10.1007/JHEP05(2021)048  

   Gross, David J.; Rosenhaus, Vladimir (May 2021, Journal of High Energy Physics)

   null (Ed.)

   A bstract Motivated by the desire to understand chaos in the S -matrix of string theory, we study tree level scattering amplitudes involving highly excited strings. While the amplitudes for scattering of light strings have been a hallmark of string theory since its early days, scattering of excited strings has been far less studied. Recent results on black hole chaos, combined with the correspondence principle between black holes and strings, suggest that the amplitudes have a rich structure. We review the procedure by which an excited string is formed by repeatedly scattering photons off of an initial tachyon (the DDF formalism). We compute the scattering amplitude of one arbitrary excited string and any number of tachyons in bosonic string theory. At high energies and high mass excited state these amplitudes are determined by a saddle-point in the integration over the positions of the string vertex operators on the sphere (or the upper half plane), thus yielding a generalization of the “scattering equations”. We find a compact expression for the amplitude of an excited string decaying into two tachyons, and study its properties for a generic excited string. We find the amplitude is highly erratic as a function of both the precise excited string state and of the tachyon scattering angle relative to its polarization, a sign of chaos. 

   more » « less
2. The effect of CO rotation from shaped pulse polarization on reactions that form C ₂

   https://doi.org/10.1039/c8cp06917d  

   Ogden, Hannah M.; Michael, Tara J.; Murray, Matthew J.; Liu, Qingnan; Toro, Carlos; Mullin, Amy S. (July 2019, Physical Chemistry Chemical Physics)

   The effect of CO rotational energy on bimolecular reactions to form electronically excited C 2 is reported here. The reactions are initiated by CO multiphoton absorption of 800 nm light in strong optical fields using two different polarization configurations based on shaped chirped pulses. The observation of Swan band emission indicates that C 2 (d 3 Π g ) is a reaction product. The optical polarization is in the form of either an optical centrifuge or a dynamic polarization grating. In each case, the strong field aligns CO molecules and induces multiphoton absorption. Power-dependent measurements indicate at least seven photons are absorbed by CO; CO(a 3 Π) is a likely reactant candidate based on kinetic modeling. Relative reaction efficiencies are determined by measuring Swan band emission intensities. For a CO pressure of 100 Torr and an optical intensity of I = 2.0 × 10 13 W cm −2 , the relative C 2 (d 3 Π g ) yield with the dynamic polarization grating is twice that with the optical centrifuge. The extent of CO rotational energy was determined for both optical polarizations using high-resolution transient IR absorption for a number of CO states with J = 62–73 and E rot up to 10 400 cm −1 . Optical centrifuge excitation generates at least 2.5 times more rotationally excited CO molecules per quantum state than the dynamic polarization grating. The results indicate that the effect of large amounts of CO rotational energy is to reduce the yield of the C 2 products. 

   more » « less
3. Photons from dark photon solitons via parametric resonance

   https://doi.org/10.1088/1475-7516/2023/05/015  

   Amin, Mustafa A; Long, Andrew J; Schiappacasse, Enrico D (May 2023, Journal of Cosmology and Astroparticle Physics)

   Wave-like dark matter made of spin-1 particles (dark photons) is expected to form ground state clumps called “vector solitons”, which can have different polarizations. In this work, we consider the interaction of dark photons with photons, expressed as dimension-6 operators, and study the electromagnetic radiation that arises from an isolated vector soliton due to parametric resonant amplification of the ambient electromagnetic field. We characterize the directional dependence and polarization of the outgoing radiation, which depends on the operator as well as the polarization state of the underlying vector soliton. We discuss the implications of this radiation for the stability of solitons and as a possible channel for detecting mergers of vector solitons through astrophysical observations. 

   more » « less
4. State-operator correspondence in celestial conformal field theory

   https://doi.org/10.1007/JHEP09(2021)132  

   Crawley, Erin; Miller, Noah; Narayanan, Sruthi A.; Strominger, Andrew (September 2021, Journal of High Energy Physics)

   A bstract The bulk-to-boundary dictionary for 4D celestial holography is given a new entry defining 2D boundary states living on oriented circles on the celestial sphere. The states are constructed using the 2D CFT state-operator correspondence from operator insertions corresponding to either incoming or outgoing particles which cross the celestial sphere inside the circle. The BPZ construction is applied to give an inner product on such states whose associated bulk adjoints are shown to involve a shadow transform. Scattering amplitudes are then given by BPZ inner products between states living on the same circle but with opposite orientations. 2D boundary states are found to encode the same information as their 4D bulk counterparts, but organized in a radically different manner. 

   more » « less
5. Integrating three-loop modular graph functions and transcendentality of string amplitudes

   https://doi.org/10.1007/JHEP02(2022)019  

   D’Hoker, Eric; Geiser, Nicholas (February 2022, Journal of High Energy Physics)

   A bstract Modular graph functions (MGFs) are SL(2 , ℤ)-invariant functions on the Poincaré upper half-plane associated with Feynman graphs of a conformal scalar field on a torus. The low-energy expansion of genus-one superstring amplitudes involves suitably regularized integrals of MGFs over the fundamental domain for SL(2 , ℤ). In earlier work, these integrals were evaluated for all MGFs up to two loops and for higher loops up to weight six. These results led to the conjectured uniform transcendentality of the genus-one four-graviton amplitude in Type II superstring theory. In this paper, we explicitly evaluate the integrals of several infinite families of three-loop MGFs and investigate their transcendental structure. Up to weight seven, the structure of the integral of each individual MGF is consistent with the uniform transcendentality of string amplitudes. Starting at weight eight, the transcendental weights obtained for the integrals of individual MGFs are no longer consistent with the uniform transcendentality of string amplitudes. However, in all the cases we examine, the violations of uniform transcendentality take on a special form given by the integrals of triple products of non-holomorphic Eisenstein series. If Type II superstring amplitudes do exhibit uniform transcendentality, then the special combinations of MGFs which enter the amplitudes must be such that these integrals of triple products of Eisenstein series precisely cancel one another. Whether this indeed is the case poses a novel challenge to the conjectured uniform transcendentality of genus-one string amplitudes. 

   more » « less