New physics effects from B meson decays

In this talk, we point out some of the present and future possible signatures of physics beyond the Standard Model from B-meson decays, taking R-parity conserving and violating supersymmetry as illustrative examples. An expanded version is available on hep-ph archive.     

Comment on the supersymmetry at finite temperatures

We comment on some of the general thermostatistical properties of the global supersymmetry characterized by Grassmann parameters, which are shared by the ordinary supersymmetry as well as by the BRS supersymmetry associated with any gauge symmetry including local supersymmetry.     

Dynamical stability of the BRS supersymmetry and the Gribov problem

The stability of the Becchi-Rouet-Stora supersymmetry is studied on the basis of a simple non-gauge model invariant under BRS supersymmetry. The Nambu-Goldstone theorem is stated and the spontaneous breakdown of the BRS supersymmetry is illustrated by the above non-gauge model. This indicates that the dynamical stability of BRS supersymmetry in non-abelian gauge theories should also be carefully examined, if one takes the Faddeev-Popov lagrangian as a basis of the formal canonical treatment. We show that a better understanding of the Gribov problem is required to establish the stability of the BRS supersymmetry in non-abelian gauge theories to non-perturbative accuracy.     

Gravitational gauge mediation

It is often the case that the naive introduction of the messenger sector to supersymmetry breaking models causes restoration of supersymmetry. We discuss a possibility of stabilizing the supersymmetry breaking vacuum by gravitational interaction.     

Electroweak breaking and supersymmetry breaking

We discuss the clash between the absence of fine tuning in the Higgs potential and a sufficient suppression of flavour changing neutral current transitions in supersymmetric extensions of the standard model. It is pointed out that horizontalU(1) symmetry combined with theD-term supersymmetry breaking provides a realistic framework for solving both problems.     

Neutrino mass patterns, R-parity violating supersymmetry and associated phenomenology

Motivated by the recent super-Kamiokande results on atmospheric neutrinos, we incorporate massive neutrinos, with large angle oscillation between the second and third generations, in a theory with R-parity violating supersymmetry. The general features of such a theory are briefly reviewed. We emphasize its testability through the observation of comparable numbers of muons and taus, produced together with the W-boson, in decays of the lightest neutralino. A distinctly measurable decay gap is another remarkable feature of such a scenario.     

(1+1)自由度para粒子的超对称量子力学

讨论了同阶p的一自由度para玻色子和一自由度para费米子所组成的para粒子系统的Fock态空间结构与超对称量子力学.发现除了四种退化的特殊情况之外,这个(1+1)自由度para粒子系统的态空间结构一般具有内禀二重简并性.进一步揭示了这个para量子系统除了具有动力学超对称性之外,还存在着一层隐藏的内禀超对称性,并且这种内禀超对称性对于整个系统超对称性的严格性起着十分关键的作用. 关键词： para统计 Fock态空间 超对称性     

Constructive approach to supergravity

Starting from a first-order formulation of the Lagrangian of noninteracting massless helicity-2 and helicity-3/2 particles, we deduce global supersymmetry transformations. Then, allowing the supersymmetry transformations to become local requires, if supersymmetry is to be maintained, the introduction of a unique primitive interaction through the gravitino stress tensor and torsion. Finally, the imposition of exact supersymmetry invariance leads by a short, constructive process to full supergravity and the complete form of the supersymmetry transformations. In particular, no explicit use is made of general coordinate invariance, and the self-consistency of the gravitational coupling emerges from the local supersymmetry requirement alone.     

One Fermion-Loop Correction and Supersymmetry in the Heterotic String Theory

(2, 0) world-sheet supersymmetry is shown to be one of the necessary conditions for space-time supersymmetry in most cases. Special care is taken to study the cancellation of local Lorentz and gauge anomalies caused by one fermion-loop..My computation shows that local counterterms which simultaneously restore local Lorentz and gauge invariance of the sigma model do not satisfy the criteria of (2, 0) supersymmetry. But local counterterms and the non-local part of one loop effective action are together invariant under the (2, 0) supersymmetry transformation.     

Intersectingp — p′ branes inpp-wave background

Several supergravity solutions corresponding to bothDp, as well asDp—Dp′ systems, inNS-NS andR-R pp-wave background originating fromAdS ₃ xS ³ xR ⁴ are presented. The supersymmetry properties of these solutions are analysed along with a brief outline of the world sheet construction for thep — p′ branes.     

Vanishing scalar masses in no-scale supergravity

Radiative corrections to the effective scalar potential are studied in no-scale supergravity models with local supersymmetry spontaneously broken by a gravitino mass. A simple proof is given that gauge non-singlet scalar fields acquire no supersymmetry breaking masses at the one-loop level, and a general argument is given extending this result to all orders of perturbation theory in the effective low-energy theory, proving also that no trilinear soft supersymmetry breaking terms in the effective potential are generated. These results are applicable to the four-dimensional no-scale supergravity theory obtained from the superstring after compactification, and support suggestions that the dominant source of global supersymmetry breaking in this theory may be the gaugino mass.     

Temperature and supersymmetry

We study equal-time correlation functions at finite temperature in field theories with global supersymmetry. Global supersymmetry is found to be broken at finite temperature; the ground state is not supersymmetric but no Goldstone fermion appears. The temperature dependence of the mass spectrum in the one-loop approximation and leading order in temperature is investigated in several models. In the models that we consider with spontaneous supersymmetry breaking we find that the Goldstone fermion remains massless at the one-loop level. Ward identities describing the supersymmetry of the underlying theory are checked at the one-loop level. We also discuss the situation in supergravity.     

Can supersymmetry solve the strong CP-violation problem?

We present evidence that supersymmetry can help to solve the strong CP-violation problem. This evidence is based on the observation that the θ-vacuum in supersymmetry unbroken gauge theories is a CP-invariant. We also point out that the complicated vacua structure in supersymmetrical gauge models cannot lead itself to supersymmetry breaking.     

Explicit Construction of Supercharges of Supersymmetric Nonlinear Sigma Models in 1 + 1 Spacetime Dimensions

Considering the N = 1 supersymmetry transformations of supersymmetric nonlinear sigma models in 1 + 1 dimensions we construct explicitly conserved Noether currents associated with supersymmetry transformations and derive the associated conserved charges in terms of the basic fields. We compare this result with superspace calculations. Finally we review the connection between extended supersymmetry and the geometry of the target space and derive an explicit form of the supercharges for extended supersymmetry.     

BPS States of D=4 ␣N=1 Supersymmetry

We find the combinations of momentum and domain-wall charges corresponding to BPS states preserving 1/4, 1/2 or 3/4 of D=4 N=1 supersymmetry, and we show how the supersymmetry algebra implies their stability. These states form the boundary of the convex cone associated with the Jordan algebra of 4× 4 real symmetric matrices, and we explore some implications of the associated geometry. For the Wess–Zumino model we derive the conditions for preservation of 1/4 supersymmetry when one of two parallel domain-walls is rotated and in addition show that this model does not admit any classical configurations with 3/4 supersymmetry. Our analysis also provides information about BPS states of N=1 D=4 anti-de Sitter supersymmetry. Received: 6 April 2000/ Accepted: 10 September 2000     

二维各向同性变频率谐振子的超对称性及其不变量的超对称量子力学精确解

采用超对称量子力学与不变量相结合的方法讨论了二维各向同性变频率谐振子,给出了二维各向同性变频率谐振子的不变量,采用超对称量子力学方法精确求解了不变量的本征值和本征函数,并且给出了当频率恒定时,二维常频率谐振子的本征值和本征函数的精确解.最后对不变量的超对称性进行了讨论.     

Use of compensators to break supersymmetry in an N = 1 supergravity theory

We consider an N = 1 supergravity theory with multiple compensators and show that supersymmetry is broken by a solution to the equation of motion of a compensator. When a chiral scalar superfield is coupled to supergravity, we discuss various aspects of supersymmetry breaking and show that the super-Higgs-Kibble effect is operative. Possible applications of this mechanism of supersymmetry breaking in model building and extended supergravity theories are indicated.     

(2, 0) supersymmetry and space-time supersymmetry in the heterotic string theory

Criteria for unbroken N=1 space-time supersymmetry in the heterotic string theory in the presence of background fields are discussed. We make use of the construction of the fermion vertex operator in the Neveu-Schwarz-Ramond model. (2, 0) world-sheet supersymmetry is shown to be one of the necessary conditions for space-time supersymmetry in most cases. Constraints on the various background fields implied by (2, 0) world-sheet supersymmetry are derived, taking into account the effect of σ-model loop corrections. Special care is taken to study the effect of local Lorents and gauge anomaly on these constraints. Our analysis determines the constraints unambigously up to field redefinitions.     

Supersymmetry and LHC

Motivations for introducing supersymmetry in high-energy physics are discussed along with the possibility of discovering supersymmetry at the Large Hadron Collider (LHC). Various regions of the space of parameters of the minimal supersymmetric standard model are analyzed, and phenomenological manifestations of supersymmetry inherent in these regions are discussed. The discovery potential of LHC at the planned luminosity is indicated for various channels.     

Dynamics of O(N) chiral supersymmetry at finite energy density

We consider an O(N) version of a massive, interacting, chiral supersymmetry model solved exactly in the large N limit. We demonstrate that the system approaches a stable attractor at high energy densities, corresponding to a non-perturbative state for which the relevant field quanta are massless. The state is one of spontaneously broken O(N), which, due to the influence of supersymmetry, does not become restored at high energies. Introducing soft supersymmetry breaking to the Lagrangian results in scalar masses at the soft breaking scale m_s independent of the mass scale of supersymmetry μ, with even smaller masses for the fermions.