We have presented the results of our next-to-next-to-leading order (NNLO) QCD analysis of nuclear parton distribution functions (nuclear PDFs) [Phys. Rev. D 93 (2016) 014026, arXiv:1601.00939 [hep-ph]] using all available neutral current charged-lepton ($\ell ^\pm$ + nucleus) deeply inelastic scattering (DIS) data as well as Drell-Yan (DY) cross-section ratios $σ_{\rm DY}^{A}/σ_{\rm DY}^{A^\prime}$ for a variety of nuclear targets. We have studied in detail the parametrizations and the atomic mass (A) dependence of the nuclear PDFs at NNLO at the input scale, $Q_0^2 = 2 \, {\rm GeV^2}$. Our {\tt KA15} nuclear PDFs provides a complete set of nuclear PDFs, $f_i^{(A, Z)}(x, Q^2)$, with a full functional dependence on $x$, A, $Q^2$. The uncertainties of the obtained nuclear modification factors for each parton flavour as well as the corresponding observables are estimated using the well-known Hessian method. The nuclear heavy quark contributions are also included into the analysis in the framework of zero-mass variable flavour number scheme (ZM-VFNS). We compare the results of our parametrization with all available nuclear DIS data and the results of other nuclear PDFs groups. We have found that our nuclear PDFs to be in reasonably good agreement with results in the literature. The estimates of errors provided by our global analysis ({\tt KA15}) are rather smaller than those of other groups. We have briefly reviewed different aspects of recent LHC heavy-ion collisions data including the first experimental data from the LHC proton+lead ($p-pb$) and lead+lead ($pb-pb$) run which can be used in the global fits of nuclear PDFs.
Une « actualité » française et internationale autour d’Epstein (colloques, publications, inédits) invite à revenir sur l’œuvre protéiforme du cinéaste qui est tout autant poète, essayiste, philosophe. C’est l’ouverture du fonds Epstein de la Cinémathèque française qui change désormais l’appréhension de cette œuvre et ouvre à de nouvelles approches. On en propose ici quelques-unes en complément des deux études de ce numéro en éclairant les rapports d’Epstein et du Dr Ramain, musicologue et esthéticien dont la correspondance, inédite, vient d’être versée au fonds de la Cinémathèque française ; en révélant, à partir des images mêmes du film les Bâtisseurs, un Epstein antifasciste ; en documentant les difficultés que rencontra le cinéaste théoricien après la Deuxième Guerre mondiale à publier et à se faire entendre, ignoré d’une nouvelle génération critique qui rejette « l’avant-garde » comme sa conception de la « machine » du cinéma.
In this thesis, I present dispersive treatments of two hadronic processes: the semileptonic kaon decay $K_{\ell4}$ and hadronic light-by-light scattering. The $K_{\ell4}$ decay is one of the best sources of information on some of the parameters of chiral perturbation theory. The dispersion relation for $K_{\ell4}$ provides a resummation of $ππ$- and $Kπ$-rescattering effects. In contrast to a pure chiral treatment, it reproduces the observed curvature of one of the form factors. The matching of the dispersion relation to the chiral representation of the form factors allows the extraction of the values of three low-energy constants. Hadronic light-by-light scattering appears as a virtual process in the calculation of the anomalous magnetic moment of the muon $(g-2)_μ$. For more than a decade, a discrepancy of about $3σ$ has persisted between the experimental determination and the standard-model prediction of the $(g-2)_μ$. It is expected that within a few years hadronic light-by-light scattering will dominate the uncertainty of the theory prediction of the $(g-2)_μ$. So far, only model calculations of the hadronic light-by-light contribution are available. However, in view of forthcoming $(g-2)_μ$ experiments at Fermilab and J-PARC it is crucial that the hadronic light-by-light calculation can be improved systematically. The dispersive description presented here provides a formalism for a data-driven determination of hadronic light-by-light scattering and hence opens up an avenue towards a model-independent evaluation of the $(g-2)_μ$.
Dominance of type-II seesaw mechanism for neutrino masses has attracted considerable attention because of a number of advantages. We show a novel approach to achieve Type-II seesaw dominance in non-supersymmetric $SO(10)$ grand unification where a low mass $Z^{\prime}$ boson and specific patterns of right-handed neutrino masses are predicted within the accessible energy range of the Large Hadron Collider. In spite of the high value of the seesaw scale, $M_{Δ_L} \simeq 10^8-10^9$ GeV, the model predicts new dominant contributions to neutrino-less double beta decay in the $W_L-W_L$ channel close to the current experimental limits via exchanges of heavier singlet fermions used as essential ingredients of this model even when the light active neutrino masses are normally hierarchical or invertedly hierarchical. We obtain upper bounds on the lightest sterile neutrino mass $m_s\lesssim 3.0$ GeV, $2.0$ GeV, and $0.7$ GeV for normally hierarchical, invertedly hierarchical, and quasi-degenerate patterns of light neutrino masses, respectively. The underlying non-unitarity effects lead to lepton flavor violating decay branching ratios within the reach of ongoing or planned experiments and the leptonic CP-violation parameter nearly two orders larger than the quark sector. Some of the predicted values on proton lifetime for $p\to e^+π^0$ are found to be within the currently accessible search limits. Other aspects of model applications including leptogenesis etc. are briefly indicated.
Part-3 of "Project X: Accelerator Reference Design, Physics Opportunities, Broader Impacts". The proposed Project X proton accelerator at Fermilab, with multi-MW beam power and highly versatile beam formatting, will be a unique world-class facility to explore particle physics at the intensity frontier. Concurrently, however, it can also facilitate important scientific research beyond traditional particle physics and provide unprecedented opportunities in applications to problems of great national importance in the nuclear energy and security sector. Part 1 is available as arXiv:1306.5022 [physics.acc-ph] and Part 2 is available as arXiv:1306.5009 [hep-ex].
Luis A. Anchordoqui, Ignatios Antoniadis, Haim Goldberg
et al.
We discuss the phenomenology and cosmology of a Standard-like Model inspired by string theory, in which the gauge fields are localized on D-branes wrapping certain compact cycles on an underlying geometry, whose intersection can give rise to chiral fermions. The energy scale associated with string physics is assumed to be near the Planck mass. To develop our program in the simplest way, we work within the construct of a minimal model with gauge-extended sector U (3)_B \times Sp (1)_L \times U (1)_{I_R} \times U (1)_L. The resulting U (1) content gauges the baryon number B, the lepton number L, and a third additional abelian charge I_R which acts as the third isospin component of an SU(2)_R. All mixing angles and gauge couplings are fixed by rotation of the U(1) gauge fields to a basis diagonal in hypercharge Y and in an anomaly free linear combination of I_R and B-L. The anomalous $Z'$ gauge boson obtains a string scale Stückelberg mass via a 4D version of the Green-Schwarz mechanism. To keep the realization of the Higgs mechanism minimal, we add an extra SU(2) singlet complex scalar, which acquires a VEV and gives a TeV-scale mass to the non-anomalous gauge boson Z". The model is fully predictive and can be confronted with dijet and dilepton data from LHC8 and, eventually, LHC14. We show that M_{Z"} \approx 3 - 4 TeV saturates current limits from the CMS and ATLAS collaborations. We also show that for M_{Z"} \alt 5 TeV, LHC14 will reach discovery sensitivity \agt 5σ. After that, we demostrate in all generality that Z" milli-weak interactions could play an important role in observational cosmology. Finally, we examine some phenomenological aspects of the supersymmetric extension of the D-brane construct.
We present new investigation of the Lamb shift (2P_{1/2}-2S_{1/2}) in muonic deuterium (mu d) atom using the three-dimensional quasipotential method in quantum electrodynamics. The vacuum polarization, nuclear structure and recoil effects are calculated with the account of contributions of orders alpha^3, alpha^4, alpha^5 and alpha^6. The results are compared with earlier performed calculations. The obtained numerical value of the Lamb shift 202.4139 meV can be considered as a reliable estimate for the comparison with forthcoming experimental data.
The discovery of $B_d - \bar B_d$ oscillations twenty years ago by the ARGUS collaboration marked a watershed event. It persuaded a significant part of the HEP community that the large time dependent \cp asymmetries predicted for some $B_d$ decays might be within the reach of specially designed experiments. This opened the successful era of the $B$ factories, which has a great future still ahead. After sketching the status of heavy flavour physics I describe why we need to continue a comprehensive heavy flavour program not only for its intrinsic reasons -- it is even mandated as an integral part of the LHC program. Notwithstanding the great success anticipated for the LHCb experiment I explain why a Super-Flavour Factory is an essential complement to the LHC program.
In this paper, we will construct a gauge field model, in which the masses of gauge fields are non-zero and the local gauge symmetry is strictly preserved. A SU(N) gauge field model is discussed in details in this paper. In the limit $α\longrightarrow 0$ or $α\longrightarrow \infty$, the gauge field model discussed in this paper will return to Yang-Mills gauge field model. This theory could be regarded as theoretical development of Yang-Mills gauge field theory.
The pions decouple from quarks while their coupling to nucleons $g_{πNN}$ remains unchanged at high density. This will have consequences for some recent papers.
We show that not only the hierarchical quark CKM mixing matrix but also the "bimaximal" lepton flavor mixing matrix can be derived from the same mass matrix ansatz based on the broken permutation symmetry, by assuming the hierarchy of neutrino masses to be $m_1\simeq m_2 <<m_3$. We also reproduce the recently measured angle of unitary triangle, $\sin 2β$, as well as all the observed experimental values of $V_{\tiny CKM}$ of the quark CKM matrix. And we predict Jarlskog rephasing invariant quantity, $J_{\tiny CP} \simeq 0.18 \times 10^{-4}$, and the upper bound of the same quantity in the lepton sector, $J^l_{\tiny CP} \leq 0.012$, which may be indeed large enough to generate the lepton number violation of the universe.
We present a more detailed account of our study (hep-ph/9903238) for the supersymmetry reach of the Tevatron in channels with isolated leptons and identified tau jets. We review the theoretical motivations for expecting such signatures, and describe the relevant parameter space in the minimal supergravity and the minimal gauge-mediated models. With explicit Monte Carlo simulations we then show that for certain parameter ranges, channels with two leptons and one tau jet offer a better reach in Run II than the clean trilepton signal. We emphasize than improving on tau ID is an important prerequisite for successful searches in multiple tau jet channels. Finally, we discuss some triggering issues.