TY - JOUR

T1 - Partonic behavior of string scattering amplitudes from holographic QCD models

AU - Bianchi, Massimo

AU - Firrotta, Maurizio

AU - Sonnenschein, Jacob

AU - Weissman, Dorin

N1 - Publisher Copyright:
© 2022, The Author(s).

PY - 2022/5

Y1 - 2022/5

N2 - We study the emergence of partonic behavior in scattering processes at large Mandelstam’s variable s from string amplitudes in holographic backgrounds. We generalize the approach of Polchinski and Strassler [1] in two ways. (i) We analyze several holographic confining backgrounds, in particular the hard wall model, the soft wall model and Witten’s model. (ii) In addition to deriving the asymptotic behavior of the amplitudes at fixed angle and in the Regge limit, we also expand the amplitudes around their poles, integrate over the holographic direction and then re-sum the expansion. Due to dependence of the string tension on the holographic coordinate, the resulting singularities take the form of branch points rather than poles and the amplitudes display branch cuts and acquire a finite imaginary part. This may signal the failure of the PS prescription to reproduce the correct analytic structure at low energies. We also observe that the peaks are more pronounced in the region of small s but fade away for large s. In the fixed angle approximation we find in the hard and soft wall models that A ∼ s2−∆/2 whereas in Witten’s model A ∼ s3−∆/2 and A ∼ s7/3−2∆/3 for the 11D and 10D formulations, respectively. In the Regge regime A ∼ s2t−2+α (log s/t)−1+α where α is the power found in the fixed angle regime. Using the pole expansion the result for each model is Re [A] ∼ s−1, Im [A] ∼ sα. We compute the corresponding amplitudes for mesons using open strings and find qualitatively similar results as for closed strings.

AB - We study the emergence of partonic behavior in scattering processes at large Mandelstam’s variable s from string amplitudes in holographic backgrounds. We generalize the approach of Polchinski and Strassler [1] in two ways. (i) We analyze several holographic confining backgrounds, in particular the hard wall model, the soft wall model and Witten’s model. (ii) In addition to deriving the asymptotic behavior of the amplitudes at fixed angle and in the Regge limit, we also expand the amplitudes around their poles, integrate over the holographic direction and then re-sum the expansion. Due to dependence of the string tension on the holographic coordinate, the resulting singularities take the form of branch points rather than poles and the amplitudes display branch cuts and acquire a finite imaginary part. This may signal the failure of the PS prescription to reproduce the correct analytic structure at low energies. We also observe that the peaks are more pronounced in the region of small s but fade away for large s. In the fixed angle approximation we find in the hard and soft wall models that A ∼ s2−∆/2 whereas in Witten’s model A ∼ s3−∆/2 and A ∼ s7/3−2∆/3 for the 11D and 10D formulations, respectively. In the Regge regime A ∼ s2t−2+α (log s/t)−1+α where α is the power found in the fixed angle regime. Using the pole expansion the result for each model is Re [A] ∼ s−1, Im [A] ∼ sα. We compute the corresponding amplitudes for mesons using open strings and find qualitatively similar results as for closed strings.

KW - Bosonic Strings

KW - Gauge-Gravity Correspondence

KW - Scattering Amplitudes

UR - http://www.scopus.com/inward/record.url?scp=85132648160&partnerID=8YFLogxK

U2 - 10.1007/JHEP05(2022)058

DO - 10.1007/JHEP05(2022)058

M3 - ???researchoutput.researchoutputtypes.contributiontojournal.article???

AN - SCOPUS:85132648160

SN - 1126-6708

VL - 2022

JO - Journal of High Energy Physics

JF - Journal of High Energy Physics

IS - 5

M1 - 58

ER -