120651741
Energy spectra of hadrons in deep inelastic scattering
Abstract We summarize the results of perturbative QCD analysis of particle distributions in deep inelastic lepton-hadron scattering (DIS). The role of coherent phenomena in the structure of the final state in DIS is emphasized.
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.
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.
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.
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.
125850380
Multiple Hadron Production in Parton {QCD} Jets
9965376
Telltale traces of U(1) fields in noncommutative standard model extensions
Restrictions imposed by gauge invariance in noncommutative spaces together with the effects of ultraviolet/infrared mixing lead to strong constraints on possible candidates for a noncommutative extension of the Standard Model. In this paper, we study a general class of 4-dimensional noncommutative models consistent with these restrictions. Specifically we consider models based upon a gauge theory with the gauge group U(N1) × U(N2) × ... × U(Nm) coupled to matter fields transforming in the (anti)-fundamental, bi-fundamental and adjoint representations. Noncommutativity is introduced using the Weyl-Moyal star-product approach on a continuous space-time. We pay particular attention to overall trace-U(1) factors of the gauge group which are affected by the ultraviolet/infrared mixing. We show that, in general, these trace-U(1) gauge fields do not decouple sufficiently fast in the infrared, and lead to sizable Lorentz symmetry violating effects in the low-energy effective theory. Making these effects unobservable in the class of models we consider would require pushing the constraint on the noncommutativity mass scale far beyond the Planck mass (MNC10100 MP) and severely limits the phenomenological prospects of such models.
15213237
Collinear limits in QCD from MHV rules
We consider multi-parton collinear limits of QCD amplitudes at tree level. Using the MHV formalism we specify the underlying analytic structure of the resulting multi-collinear splitting functions. We derive general results for these splitting functions that are valid for specific numbers of negative helicity partons and an arbitrary number of positive helicity partons (or vice versa).
119236962
Travels on the squark-gluino mass plane
Institut fur Theoretische Physik, Universitat Heidelberg, Germany(Dated: September 12, 2011)Soft supersymmetry breaking appears in the weak-scale e ective action but is usually generated athigher scales. For these models the structure of the renormalization group evolution down to theelectroweak scale leaves only part of the squark-gluino and slepton-gaugino mass planes accessible.Our observations divide these physical mass planes into three wedges: the rst can be reached byall models of high-scale breaking; the second can only be populated by models with a low mediationscale; in the third wedge squarks and gluinos would have to be described by an exotic theory. Allusual benchmark points reside in the rst wedge, even though an LHC discovery in the third wedge
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.
11515241
Exact results in noncommutative = 2 supersymmetric gauge theories
We study the low-energy dynamics of noncommutative = 2 supersymmetric U(N) Yang-Mills theories in the Coulomb phase. Exact results are derived for the leading terms in the derivative expansion of the wilsonian effective action. We find that in the infrared regime the U(1) subgroup decouples, and the remaining SU(N) is described by the ordinary commutative Seiberg-Witten solution. IR/UV mixing is present in the U(1), but not in SU(N). Our analysis is based on explicit perturbative and multi-instanton calculations.