A Second Look at String-Inspired Models for Proton-Proton Scattering via Pomeron Exchange

We re-examine a string dual model for elastic proton-proton scattering via Pomeron exchange. We argue that the method of "Reggeizing" a propagator to take into account an entire trajectory of exchanged particles can be generalized, in particular by modifying the value of the mass-shell parameter in the model. We then fit the generalized model to scattering data at large s and small t. The fitting results are inconclusive, but suggest that a better fit might be obtained by allowing the mass-shell to vary. The model fits the data equally well (roughly) for a wide range of values of the mass-shell parameter, but the other fitting parameters (the slope and intercept of the Regge trajectory, and the coupling constant and dipole mass from the proton-proton-glueball coupling) are then inconsistent with what we expect. On the other hand, using the traditional method of Reggeization generates a weaker fit, but the other parameters obtain more physically reasonable values. In analyzing the fitting results, we also found that our model is more consistent with the sqrt(s) = 1800 GeV coming from the E710 experiment than that coming from the CDF experiment, and that our model has the greatest discrepancy with the data in the range 0.5 GeV^2 < |t| < 0.6 GeV^2, suggesting that the transition from soft Pomeron to hard Pomeron may occur closer to t = -0.5 GeV^2 rather than t = -0.6 GeV^2 as previously thought.Comment: 16 pages, 7 figures, 2 table

SELEX: barcodes of sequencing primers and numbers of nested PCR cycles used to attach sequencing primers (see Table 4 for sequences of sequencing primers).

<p>SELEX: barcodes of sequencing primers and numbers of nested PCR cycles used to attach sequencing primers (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0100572#pone-0100572-t004" target="_blank">Table 4</a> for sequences of sequencing primers).</p

Times at which supernatants were collected in single-step selection, barcodes of sequencing primers (see Table 4) that were used to amplify DNA from these supernatants, and number of nested PCR cycles (<b><i>n</i></b>) used to attach primers (see Table 4 for sequences of sequencing primers).

<p>Times at which supernatants were collected in single-step selection, barcodes of sequencing primers (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0100572#pone-0100572-t004" target="_blank">Table 4</a>) that were used to amplify DNA from these supernatants, and number of nested PCR cycles (<b><i>n</i></b>) used to attach primers (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0100572#pone-0100572-t004" target="_blank">Table 4</a> for sequences of sequencing primers).</p

Extraction of aptamer sequences from NGS reads.

<p><b>a)</b> Informatics pipeline as applied to DNA retained on the beads in single-step selection. Key: numbers in rectangles show the number of sequences at each stage in the pipeline. <b>b)</b> Linkers 4–6 identified in round 5 of SELEX.</p

Structure of the combinatorial library that was screened for bivalent aptamers.

<p>Structure of the combinatorial library that was screened for bivalent aptamers.</p

Sequences of aptamers investigated in affinity and inhibition assays; the sequences of APT-15 and APT-29 in bivalent aptamers are underlined.

<p>Sequences of aptamers investigated in affinity and inhibition assays; the sequences of APT-15 and APT-29 in bivalent aptamers are underlined.</p

SELEX: Concentrations of DNA, magnetic beads and number of additional PCR cycles.

<p>SELEX: Concentrations of DNA, magnetic beads and number of additional PCR cycles.</p

Workflow of single step selection.

<p><b>a)</b> Key: size selection  =  preparative electrophoresis; QC  =  quality control; NGS  =  next generation sequencing. <b>b)</b> Detail of one cycle of dissociation. Thrombin-coated magnetic beads (MBs) with bound DNA are incubated for time <b>t</b> and then magnetically precipitated. DNA in the supernatant was extracted and fed into PCR I, and the MBs were re-suspended for a new cycle of dissociation. <b>c</b>) Bar-chart showing durations (<b>t</b>) of the dissociation cycles.</p

Bivalent Aptamer Structures.

<p><b>a)</b> Predicted structure of bivalent aptamer based on Linker 2. <b>b)</b> Structures of truncated derivatives of bivalent aptamer based on linker 2; excised bases are shown as grey circles.</p

Bar graphs showing enrichment of motifs 1–3 in each cycle of single-step selection, and motifs 4–6 in each round of SELEX.

<p>Bar graphs showing enrichment of motifs 1–3 in each cycle of single-step selection, and motifs 4–6 in each round of SELEX.</p