This paper describes the ATLAS experiment as installed in i ts experimental cavern at point 1 at CERN. It also presents a brief overview of the expec ted performance of the detector.

http://absimage.aps.org/image/SES08/MWS_SES08-2008-020010.pdf

The ATLAS Experiment at the CERN Large Hadron Collider

Superstring theoryをめぐって(放談室)

We present a preliminary set of updated NLO parton distributions. For the first time we have a quantitative extraction of the strange quark and antiquark distributions and their uncertainties determined from CCFR and NuTeV dimuon cross sections. Additional jet data from HERA and the Tevatron improve our gluon extraction. Lepton asymmetry data and neutrino structure functions improve the flavour separation, particularly constraining the down quark valence distribution.

http://inspirehep.net/record/752235/files/arXiv:0706.0456.pdf

Parton distributions for the LHC

This is a review paper about neutrino mass and mixing and flavour model building strategies based on discrete family symmetry. After a pedagogical introduction and overview of the whole of neutrino physics, we focus on the PMNS mixing matrix and the latest global fits following the Daya Bay and RENO experiments which measure the reactor angle. We then describe the simple bimaximal, tri-bimaximal and golden ratio patterns of lepton mixing and the deviations required for a non-zero reactor angle, with solar or atmospheric mixing sum rules resulting from charged lepton corrections or residual trimaximal mixing. The different types of see-saw mechanism are then reviewed as well as the sequential dominance mechanism. We then give a mini-review of finite group theory, which may be used as a discrete family symmetry broken by flavons either completely, or with different subgroups preserved in the neutrino and charged lepton sectors. These two approaches are then reviewed in detail in separate chapters including mechanisms for flavon vacuum alignment and different model building strategies that have been proposed to generate the reactor angle. We then briefly review grand unified theories (GUTs) and how they may be combined with discrete family symmetry to describe all quark and lepton masses and mixing. Finally, we discuss three model examples which combine an SU(5) GUT with the discrete family symmetries A₄, S₄ and Δ(96).

https://iopscience.iop.org/article/10.1088/0034-4885/76/5/056201/pdf

Neutrino Mass and Mixing with Discrete Symmetry

This paper describes the physics case for a new fixed target facility at CERN SPS. The SHiP (search for hidden particles) experiment is intended to hunt for new physics in the largely unexplored domain of very weakly interacting particles with masses below the Fermi scale, inaccessible to the LHC experiments, and to study tau neutrino physics. The same proton beam setup can be used later to look for decays of tau-leptons with lepton flavour number non-conservation, $\tau \to 3\mu $ and to search for weakly-interacting sub-GeV dark matter candidates. We discuss the evidence for physics beyond the standard model and describe interactions between new particles and four different portals—scalars, vectors, fermions or axion-like particles. We discuss motivations for different models, manifesting themselves via these interactions, and how they can be probed with the SHiP experiment and present several case studies. The prospects to search for relatively light SUSY and composite particles at SHiP are also discussed. We demonstrate that the SHiP experiment has a unique potential to discover new physics and can directly probe a number of solutions of beyond the standard model puzzles, such as neutrino masses, baryon asymmetry of the Universe, dark matter, and inflation.

/pdf/a-facility-to-search-for-hidden-particles-at-the-cern-sps-3pxaggnjt6.pdf

A facility to search for hidden particles at the CERN SPS: the SHiP physics case.

Proton stability in grand unified theories, in strings and in branes

We demonstrate how to systematically test a well-motivated mechanism for neutrino mass generation (type II seesaw) at the LHC, in which a Higgs triplet is introduced In the optimistic scenarios with a small Higgs triplet vacuum expectation value ${v}_{\ensuremath{\Delta}}l{10}^{\ensuremath{-}4}\text{ }\text{ }\mathrm{GeV}$, one can look for clean signals of lepton-number violation in the decays of doubly charged (${H}^{\ifmmode\pm\else\textpm\fi{}\ifmmode\pm\else\textpm\fi{}}$) and singly charged (${H}^{\ifmmode\pm\else\textpm\fi{}}$) Higgs bosons to distinguish the normal hierarchy (NH), the inverted hierarchy (IH), and the quasidegenerate (QD) spectrum for the light neutrino masses The observation of either ${H}^{+}\ensuremath{\rightarrow}{\ensuremath{\tau}}^{+}\overline{\ensuremath{\nu}}$ or ${H}^{+}\ensuremath{\rightarrow}{e}^{+}\overline{\ensuremath{\nu}}$ will be particularly robust for the spectrum test since they are independent of the unknown Majorana phases The ${H}^{++}$ decays moderately depend on a Majorana phase ${\ensuremath{\Phi}}_{2}$ in the NH, but sensitively depend on ${\ensuremath{\Phi}}_{1}$ in the IH In a less favorable scenario ${v}_{\ensuremath{\Delta}}g2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}\text{ }\text{ }\mathrm{GeV}$, when the leptonic channels are suppressed, one needs to observe the decays ${H}^{+}\ensuremath{\rightarrow}{W}^{+}{H}_{1}$ and ${H}^{+}\ensuremath{\rightarrow}t\overline{b}$ to confirm the triplet-doublet mixing which in turn implies the existence of the same gauge-invariant interaction between the lepton doublet and the Higgs triplet responsible for the neutrino mass generation In the most optimistic situation, ${v}_{\ensuremath{\Delta}}\ensuremath{\sim}{10}^{\ensuremath{-}4}\text{ }\text{ }\mathrm{GeV}$, both channels of the lepton pairs and gauge boson pairs may be available simultaneously The determination of their relative branching fractions would give a measurement for the value of ${v}_{\ensuremath{\Delta}}$

Neutrino masses and the CERN LHC: Testing the type II seesaw mechanism

We investigate a simple theory where baryon number (B) and lepton number (L) are local gauge symmetries. In this theory B and L are on the same footing and the anomalies are canceled by adding a single new fermionic generation. There is an interesting realization of the seesaw mechanism for neutrino masses. Furthermore, there is a natural suppression of flavor violation in the quark and leptonic sectors since the gauge symmetries and particle content forbid tree level flavor changing neutral currents involving the quarks or charged leptons. Also one finds that the stability of a dark matter candidate is an automatic consequence of the gauge symmetry. Some constraints and signals at the Large Hadron Collider are briefly discussed.

Baryon and Lepton Number as Local Gauge Symmetries

Models where the baryon (B) and lepton (L) numbers are local gauge symmetries that are spontaneously
broken at a low scale are revisited. We find new extensions of the standard model which predict
the existence of fermions that carry both baryon and lepton numbers (i.e., leptoquarks). The local baryonic
and leptonic symmetries can be broken at a scale close to the electroweak scale and we do not need to
postulate the existence of a large desert to satisfy the experimental constraints on baryon number violating
processes like proton decay.

/pdf/gauge-theory-for-baryon-and-lepton-numbers-with-leptoquarks-4v2v4e2ehs.pdf

Gauge Theory for Baryon and Lepton Numbers with Leptoquarks

We study the minimal gauged U(1){sub B-L} supersymmetric model and show that it provides an attractive theory for spontaneous R-parity violation. Both U(1){sub B-L} and R parity are broken by the vacuum expectation value of the right-handed sneutrino (proportional to the soft supersymmetry masses), thereby linking the B-L and soft SUSY scales. In this context we find a consistent mechanism for generating neutrino masses and a realistic mass spectrum, all without extending the Higgs sector of the minimal supersymmetry standard model. We discuss the most relevant collider signals and the connection between the Z{sup '} gauge boson and R-parity violation.

Pavel Fileviez Pérez

Papers

Proton stability in grand unified theories, in strings and in branes

Neutrino masses and the CERN LHC: Testing the type II seesaw mechanism

Baryon and Lepton Number as Local Gauge Symmetries

Gauge Theory for Baryon and Lepton Numbers with Leptoquarks

Minimal gauged U(1) B-L model with spontaneous R parity violation.