125436854
The Azimuthal Asymmetry of {QCD} Jets as Experimentum Crucis for String Fragmentation Picture
119379184
Radiative corrections to the hadronic cross-section measurement at DA$\Phi$NE
Abstract. The hadronic invariant mass distribution for the process of electron–positron annihilation into a pair of charged pions accompanied by a photon radiated from the initial state has been studied for the region of DA$\Phi$NE energies. The Born cross–section and the electromagnetic radiative corrections to it are calculated for realistic conditions of the KLOE detector. The dependence on the physical parameters which define the event selection is obtained.
124029542
On the sensitivity of the inclusive distributions in parton jets to the coherence effects in QCD gluon cascades
The KNO multiplicity distributions and properties of two-particle correlations in QCD jets are considered in the framework of the perturbative approach accounting for effects of the coherence in the soft gluon bremsstrahlung.
125850380
Multiple Hadron Production in Parton {QCD} Jets
119436494
QCD Interconnection Effects
Heavy objects like the W, Z and t are short-lived compared with typical hadronization times. When pairs of such particles are produced, the subsequent hadronic decay systems may therefore become interconnected. We study such potential effects at Linear Collider energies.
117871006
Pomeron universality from identical pion correlations at the LHC
Abstract Bose–Einstein correlations of identical pions produced in high-energy pp collisions at the LHC allow a probe of the Pomeron exchange mechanism. The size of the domain which emits the pions depends on the multiplicity of events, but not on the collider energy. This confirms the universal structure of Pomeron exchange. The data at relatively low multiplicities indicate that the size of the source created by one-Pomeron exchange is much less than the size of the proton.
14801216
Instanton test of non-supersymmetric deformations of the AdS5 × S5
We consider instanton effects in a non-supersymmetric gauge theory obtained by marginal deformations of the = 4 SYM. This gauge theory is expected to be dual to type IIB string theory on the AdS5 times deformed-S5 background. From an instanton calculation in the deformed gauge theory we extract the prediction for the dilaton-axion field τ in dual string theory. In the limit of small deformations where the supergravity regime is valid, our instanton result reproduces the expression for τ of the supergravity solution found by Frolov.
14016091
Multi - instantons and Maldacena's conjecture
We examine certain n-point functions Gn in = 4 supersymmetric SU(N) gauge theory at the conformal point. In the large-N limit, we are able to sum all leading-order multi-instanton contributions exactly. We find compelling evidence for Maldacena's conjecture: (1) The large-N k-instanton collective coordinate space has the geometry of AdS5 × S5, (2) In exact agreement with type IIB superstring calculations, at the k-instanton level, Gn = N1/2g8kn−7/2e−8π2kg2∑d|kd−2Fn(x1,...,xn), where Fn is identical to a convolution of n bulk-to-boundary SUGRA propagators.
119197756
Direct SUSY Searches at the LHC in the light of LEP Higgs bounds
A bstractIn this note we compare the latest 1.04 fb−1 LHC searches for squarks and gluinos from jets and missing transverse momentum (MET) with constraints arising from the LEP Higgs bound. For General Gauge Mediation models with moderate values of tan(β) we find that the zero-lepton MET searches of supersymmetry at the LHC are only starting to be competitive with the Higgs bounds from LEP. From this perspective and for such models, the SUSY searches at the LHC are still very much in the beginning.
119190421
Mass sum rules and the role of the messenger scale in General Gauge Mediation
In General Gauge Mediation (GGM), supersymmetry breaking is communicated to the Standard Model (MSSM) sector via gauge interactions at a high scale which we refer to as the messenger scale. At this scale GGM predicts certain sum rules between the MSSM sfermion masses. We investigate the validity and the ultimate fate of these sum rules after RG evolution down to the electroweak scale where the mass spectrum will be probed at colliders. We find that the sum rules hold for the first two generations. However the third generation (where sfermions are lightest) violates one of the two sum rules by 10 to 50% over the explored parameter space. This constrains and quantifies the potential use of sum rules as a signature of gauge mediation. We also comment on the role played by the messenger scale in single-and multi-scale GGM models.
53536923
Dark matter monopoles, vectors and photons
A bstractIn a secluded dark sector which is coupled to the Standard Model via a Higgs portal interaction we arrange for the existence of ’t Hooft-Polyakov magnetic monopoles and study their implications for cosmology. We point out that a dark sector which can accommodate stable monopoles will also contain massless dark photons γ′ as well as charged massive vector bosons W±′. The dark matter in this scenario will be a combination of magnetically and electrically charged species under the unbroken U(1) subgroup of the dark sector. We estimate the cosmological production rate of monopoles and the rate of monopole-anti-monopole annihilation and conclude that monopoles with masses of few hundred TeV or greater, can produce sizeable contributions to the observed dark matter relic density. We scan over the parameter space and compute the relic density for monopoles and vector bosons. Turning to dark photons, we compute their contribution to the measured density of relativistic particles Neff and also apply observational constraints from the Bullet cluster and other large scale galaxies on long-range interactions of monopoles and of dark vector bosons. At scales relevant for dwarf galaxies we identify regions on the parameter space where self-interacting monopole and vector dark mater components can aid solving the core-vs-cusp and the too-big-to-fail problems.