Generalized Gribov-Lipatov Reciprocity and AdS/CFT

Planar N=4 SYM theory and QCD share the gluon sector, suggesting the investigation of Gribov-Lipatov reciprocity in the supersymmetric theory. Since the AdS/CFT correspondence links N=4 SYM and superstring dynamics on AdS5xS5, reciprocity is also expected to show up in the quantum corrected energies of certain classical string configurations dual to gauge theory twist-operators. We review recent results confirming this picture and revisiting the old idea of Gribov-Lipatov reciprocity as a modern theoretical tool useful for the study of open problems in AdS/CFT.Comment: 42 pages. Submitted to Advances in High Energy Physics, special issue on the "Gauge/String duality

New Physics signals from measurable polarization asymmetries at LHC

We propose a new type of Z polarization asymmetry in bottom-Z production at LHC that should be realistically measurable and would provide the determination of the so-called $A_b$ parameter, whose available measured value still appears to be in disagreement with the Standard Model prediction. This polarization can be measured independently of a possible existence of Supersymmetry. If Supersymmetry is found, a second polarization, i.e. the top longitudinal polarization in top-charged Higgs production, would neatly identify the $\tan \beta$ parameter. In this case, the value of $A_b$ should be in agreement with the Standard Model. If Supersymmetry does not exist, a residual disagreement of $A_b$ from the Standard Model prediction would be a clean signal of New Physics of "non Supersymmetric" origin.Comment: typo correcte

Strong and Electro-Weak Supersymmetric Corrections to Single Top Processes at the Large Hadron Collider

We present the one-loop corrections originating from Quantum Chromo-Dynamics (QCD) and Electro-Weak (EW) interactions of Supersymmetric (SUSY) origin within the Minimal Supersymmetric Standard Model (MSSM) to the single-top processes bq -> tq' and qbar q' -> tbar b. We illustrate their impact onto top quark observables accessible at the Large Hadron Collider (LHC) in the 't+jet' final state, such as total cross section, several differential distributions and left-right plus forward-backward asymmetries. We find that in many instances these effects can be observable for planned LHC energies and luminosities, quite large as well as rather sensitive to several MSSM parameters.Comment: 22 pages, 10 figures; added a brief comment on the dependence of results on the value of top mass; corrected typo

The relevance of virtual electroweak effects in the overall tt-channel single top production at LHC

We compute the complete one loop electroweak effects in the MSSM for the eight processes of single top (and single antitop) production in the $t$-channel at hadron colliders, generalizing a previous analysis performed for the dominant $dt$ final state. The results are quite similar for all processes, showing an impressively large Standard Model effect and a generally modest genuine SUSY contribution in the mSUGRA scenario. The one loop effect on the total rate is shown and the possibility of measuring it at LHC is discussed.Comment: 15 pages, 7 eps figure

Associated production of charged Higgs and top at LHC: the role of the complete electroweak supersymmetric contribution

The process of charged Higgs production in association with a top quark at the LHC has been calculated at the complete NLO electroweak level both in a Two Higgs Doublets Model and in the Minimal Supersymmetric Standard Model, assuming a mSUGRA breaking scheme. We have numerically explored the size of the one-loop corrections in two typical supersymmetric scenarios, with particular attention to the tan beta dependence, and we have found that they remain perturbatively small but possibly sizable, reaching a 20% limit for extreme values of tan beta, when the complete set of Feynman diagrams is taken into account.Comment: 22 pages, 5 figures, reference adde

Quantum corrections to spinning superstrings in AdS_3 x S^3 x M^4: determining the dressing phase

We study the leading quantum string correction to the dressing phase in the asymptotic Bethe Ansatz system for superstring in AdS_3 x S^3 x T^4 supported by RR flux. We find that the phase should be different from the BES phase appearing in the AdS_5 x S^5 case. We use the simplest example of a rigid circular string with two equal spins in S^3 and also consider the general approach based on the algebraic curve description. We also discuss the case of the AdS_3 x S^3 x S^3 x S^1 theory and find the dependence of the 1-loop correction to the effective string tension function h(\lambda) (expected to enter the magnon dispersion relation) on the parameters alpha related to the ratio of the two 3-sphere radii. This correction vanishes in the AdS_3 x S^3 x T^4 case.Comment: 34 pages; v2: typos fixed, references added, minor corrections; v3: some explanations and sect.4.4 are added; references adde

"Short" spinning strings and structure of quantum AdS_5 x S^5 spectrum

Using information from the marginality conditions of vertex operators for the AdS_5 x S^5 superstring, we determine the structure of the dependence of the energy of quantum string states on their conserved charges and the string tension proportional to lambda^(1/2). We consider states on the leading Regge trajectory in the flat space limit which carry one or two (equal) spins in AdS_5 or S^5 and an orbital momentum in S^5, with Konishi multiplet states being particular cases. We argue that the coefficients in the energy may be found by using a semiclassical expansion. By analyzing the examples of folded spinning strings in AdS_5 and S^5 as well as three cases of circular two-spin strings we demonstrate the universality of transcendental (zeta-function) parts of few leading coefficients. We also show the consistency with target space supersymmetry with different states belonging to the same multiplet having the same non-trivial part of the energy. We suggest, in particular, that a rational coefficient (found by Basso for the folded string using Bethe Ansatz considerations and which, in general, is yet to be determined by a direct two-loop string calculation) should, in fact, be universal.Comment: 42p, Latex v2: Comments and summary table of coefficients added v3: misprints corrected; dependence on winding number added in appendix

Supersymmetry spectroscopy in stop-chargino production at LHC

We consider the process of associated stop-chargino production in the MSSM at LHC and show that, at the simplest Born level, the production rate is dramatically sensitive to the choice of the benchmark points, oscillating from potentially "visible" maxima of the picobarn size to much smaller, hardly "visible", values. Adopting a canonical choice of SM type CKM matrices, we also show that in some "visible" cases the total rate exhibits a possibly relevant dependence on tan(beta).Comment: 23 pages, 18 eps figure

Associated tW production at LHC: a complete calculation of electroweak supersymmetric effects at one loop

We compute, in the MSSM framework, the total electroweak contributions at one loop for the process pp -> tW+X, initiated by the parton process bg -> tW. The supersymmetric effect is analyzed for various choices of the SUSY benchmark points. Choosing realistic unpolarized and polarized experimental quantities, we show the size of the various effects and discuss their dependence on the MSSM parameters.Comment: 32 pages, 9 eps figure

Semi-inclusive bottom-Higgs production at LHC: The complete one-loop electroweak effect in the MSSM

We present the first complete calculation of the one-loop electroweak effect in the process of semi-inclusive bottom-Higgs production at LHC in the MSSM. The size of the electroweak contribution depends on the choice of the final produced neutral Higgs boson, and can be relevant, in some range of the input parameters. A comparison of the one-loop results obtained in two different renormalization schemes is also performed, showing a very good NLO scheme independence. We further comment on two possible, simpler, approximations of the full NLO result, and on their reliabilty