Quantum Gravity Effects in Black Holes at the LHC

We study possible back-reaction and quantum gravity effects in the evaporation of black holes which could be produced at the LHC through a modification of the Hawking emission. The corrections are phenomenologically taken into account by employing a modified relation between the black hole mass and temperature. The usual assumption that black holes explode around $1$TeV is also released, and the evaporation process is extended to (possibly much) smaller final masses. We show that these effects could be observable for black holes produced with a relatively large mass and should therefore be taken into account when simulating micro-black hole events for the experiments planned at the LHC.Comment: 14 pages, 8 figures, extended version of hep-ph/0601243 with new analysis of final products, final version accepted for publication in J. Phys.

On the Spontaneous CP Breaking at Finite Temperature in a Nonminimal Supersymmetric Standard Model

We study the spontaneous CP breaking at finite temperature in the Higgs sector in the Minimal Supersymmetric Standard Model with a gauge singlet. We consider the contribution of the standard model particles and that of stops, charginos, neutralinos, charged and neutral Higgs boson to the one-loop effective potential. Plasma effects for all bosons are also included. Assuming CP conservation at zero temperature, so that experimental constraints coming from, {\it e.g.}, the electric dipole moment of the neutron are avoided, and the electroweak phase transition to be of the first order and proceeding via bubble nucleation, we show that spontaneous CP breaking cannot occur inside the bubble mainly due to large effects coming from the Higgs sector. However, spontaneous CP breaking can be present in the region of interest for the generation of the baryon asymmetry, namely inside the bubble wall. The important presence of very tiny explicit CP violating phases is also commented.Comment: 28 pages, 4 figures available upon request, DFPD 94/TH/38 and SISSA 94/81-A preprint

How generic is cosmic string formation in SUSY GUTs

We study cosmic string formation within supersymmetric grand unified theories. We consider gauge groups having a rank between 4 and 8. We examine all possible spontaneous symmetry breaking patterns from the GUT down to the standard model gauge group. Assuming standard hybrid inflation, we select all the models which can solve the GUT monopole problem, lead to baryogenesis after inflation and are consistent with proton lifetime measurements. We conclude that in all acceptable spontaneous symmetry breaking schemes, cosmic string formation is unavoidable. The strings which form at the end of inflation have a mass which is proportional to the inflationary scale. Sometimes, a second network of strings form at a lower scale. Models based on gauge groups which have rank greater than 6 can lead to more than one inflationary era; they all end by cosmic string formation.Comment: 31 pages, Latex, submitted to PR

Cosmological constraints on R-parity violation from neutrino decay

If the neutrino mass is non-zero, as hinted by several experiments, then R-parity-violating supersymmetric Yukawa couplings can drive a heavy neutrino decay into lighter states. The heavy neutrino may either decay radiatively into a lighter neutrino, or it may decay into three light neutrinos through a Z-mediated penguin. For a given mass of the decaying neutrino, we calculate its lifetime for the various modes, each mode requiring certain pairs of R-parity-violating couplings be non-zero. We then check whether the calculated lifetimes fall in zones allowed or excluded by cosmological requirements. For the latter case, we derive stringent new constraints on the corresponding products of R-parity-violating couplings for given values of the decaying neutrino mass.Comment: 13 pages, Latex, uses axodraw.sty; version to appear in Physical Review

Simple Dynamics on the Brane

We apply methods of dynamical systems to study the behaviour of the Randall-Sundrum models. We determine evolutionary paths for all possible initial conditions in a 2-dimensional phase space and we investigate the set of accelerated models. The simplicity of our formulation in comparison to some earlier studies is expressed in the following: our dynamical system is a 2-dimensional Hamiltonian system, and what is more advantageous, it is free from the degeneracy of critical points so that the system is structurally stable. The phase plane analysis of Randall-Sundrum models with isotropic Friedmann geometry clearly shows that qualitatively we deal with the same types of evolution as in general relativity, although quantitatively there are important differences.Comment: an improved version, 34 pages, 9 eps figure

Recycling universe

If the effective cosmological constant is non-zero, our observable universe may enter a stage of exponential expansion. In such case, regions of it may tunnel back to the false vacuum of an inflaton scalar field, and inflation with a high expansion rate may resume in those regions. An ``ideal'' eternal observer would then witness an infinite succession of cycles from false vacuum to true, and back. Within each cycle, the entire history of a hot universe would be replayed. If there were several minima of the inflaton potential, our ideal observer would visit each one of these minima with a frequency which depends on the shape of the potential. We generalize the formalism of stochastic inflation to analyze the global structure of the universe when this `recycling' process is taken into account.Comment: 43 pages, 10 figure

Inflation in Supersymmetric Unified Theories

We construct supersymmetric unified models which automatically lead to a period of inflation. The models all involve a U(1) symmetry which does not belong to the MSSM. We consider three different types of models depending on whether this extra U(1) is the subgroup of a non abelian gauge group, is a U(1) factor belonging to the visible sector or is a U(1) factor belonging to the hidden sector. Depending on the structure of the unified theory, on the spontaneous symmetry breaking pattern and on whether we have global or local supersymmetry, inflation may be driven by the non-vanishing vacuum expectation value of a F-term or by that of a D-term. In both scenarios cosmic strings form at the end of inflation, and they have different properties in each model. Both inflation and cosmic strings contribute to the CMBR temperature anisotropies. We show that the strings contribute to the $C_l$'s up to the level of 75 %. Hence the contribution from strings to the CMBR and to the density perturbations in the early Universe which lead to structure formation cannot be neglected. We also discuss a very interesting class of models which involve a $U(1)_{B-L}$ gauge symmetry.Comment: 22 pages, uses Revte

Non-perturbative renormalization of QCD

In these lectures, we discuss different types of renormalization problems in QCD and their non-perturbative solution in the framework of the lattice formulation. In particular the recursive finite size methods to compute the scale-dependence of renormalized quantities is explained. An important ingredient in the practical applications is the Schr\"odinger functional. It is introduced and its renormalization properties are discussed. Concerning applications, the computation of the running coupling and the running quark mass are covered in detail and it is shown how the $\Lambda$-parameter and renormalization group invariant quark mass can be obtained. Further topics are the renormalization of isovector currents and non-perturbative Symanzik improvement.Comment: 49 pages, lectures at Schladming-9

Effect of the Size of Clods Contained Covering Soil on the Seedling Emergence of Rice Plant Sown under Upland Field Condition

水稲農林23号を用いて, 覆土の土塊の大きさが, 乾田に深播き(覆土7cm)された個体の出芽ならびに幼苗諸器官の長さに及ぼす影響について, 覆土が3cmの場合と比較しながら検討した。乾田に播種された種子が大きい土塊で覆土されると, 覆土が3cmの場合には鞘葉の伸長が抑制される。しかし, 不完全葉はほとんどの個体で3cm以上に伸長する。また大土塊の間隙が小土塊で充足された場合は, 鞘葉および不完全葉ともに, 大土塊だけの場合よりも長くなる。その結果, すべての区の出芽率は, 播種後12日目には90%以上に達する。覆土が7cmの場合には, 覆土の土塊が大きくても, 鞘葉および不完全葉は覆土が3cmの場合よりも著しく長くなる。その結果, 第1本葉が不完全葉から抽出する位置が高められる。しかし, 鞘葉および不完全葉の伸長のみによっては出芽することはできず, 出芽するためには, 第2節間および第1本葉が伸長しなければならない。覆土の土塊が大きい場合には, 第2節間の伸長が抑制される。と同時に, 出芽までの間に幼芽の伸長を妨げる土塊の数も多くなるので, 出芽率は著しく低下する。しかし, 大土塊の間隙が小さい土塊によって充足されると, 第2節間が著しく長くなり, 第1本葉をおしあげる。その結果, 出芽率は単一土塊の場合に比べて著しく高まる。以上の結果と土壌中への光の侵入量との関係について, 若干考察した。 / This experiment was carried out to clarify the effects of size of clods in covering soil on the emergence and the elongation of rice seedling sown under upland field condition in pot (10cm×10cm×12cm) culture. Variety used was Norin No. 23. Seeds were covered with 3cm and 7cm depth of soil. In the case of 3cm in depth of seeding, if seeds were covered with larger clods, the elongation of coleoptile was inhibited, but the profile elongated longer than 3cm. When gaps between larger clods were filled with smaller clods, the length of coleoptile and profile became longer. Consequently, the emergence percentage of all plots reached more than 90% the 12th day after seeding. In the case of 7cm in depth of seeding, if seeds were covered with larger clods, coleoptile or profile elongated to 3 to 4cm in length, but the elongation of second internode was inhibited. As a result, the emergence percentage decreased significantly. When gaps between larger clods were filled with smaller clods, however, the length of second internode increased and first leaf was pushed up through the soil by second internode. Consequently, the emergence percentage increased significantly