51693431
Supersymmetric Jarlskog invariants: The neutrino sector
We generalize the notion of the Jarlskog invariant to supersymmetric models with right-handed neutrinos. This allows us to formulate basis-independent necessary and sufficient conditions for $CP$ conservation in such models.
119352335
Constraints on gauged B-3L(tau) and related theories
We consider extensions of the Standard Model with an extra U(1) gauge boson which couples to B-(alpha L_e + beta L_mu + gamma L_tau) with alpha + beta + gamma = 3. We show that the extra gauge boson necessarily mixes with the Z leading to potentially significant corrections to the Z-f-fbar vertex. The constraints on the size of this correction imposed by the Z-pole data from LEP and SLD are derived.
17840929
Torsion constraints in the Randall-Sundrum scenario
Torsion appears due to fermions coupled to gravity and leads to the strongest particle physics bounds on flat extra dimensions. In this work, I consider torsion constraints in the case of a warped extra dimension with brane and bulk fermions. From current data I obtain a $3\ensuremath{\sigma}$ bound on the TeV-brane mass scale ${\ensuremath{\Lambda}}_{\ensuremath{\pi}}g~2.2 (10) \mathrm{TeV}$ for the anti-de Sitter curvature $k=1(0.01)$ in (reduced) Planck units. If Dirac or light sterile neutrinos reside on the brane, the bound increases to 17 (78) TeV.
118714441
The NMSSM and string theory
Abstract We study the possibility of constructing the NMSSM from the heterotic string. String-derived NMSSMs are much more rare than MSSMs due to the extra requirement that there exist a light singlet which couples to the Higgs pairs. They share the common feature that the singlet self-interactions are typically suppressed, leading to either the “decoupling” or the Peccei–Quinn limit of the NMSSM. In the latter case, the spectrum contains a light pseudoscalar which may be relevant to the MSSM fine-tuning problem. We provide a Z 6 heterotic orbifold example of the NMSSM with approximate Peccei–Quinn symmetry, whose origin lies in the string selection rules combined with our choice of the vacuum configuration.
15991488
Heterotic string backgrounds and CP violation
Abstract In the framework of Z N orbifolds, we discuss effects of heterotic string backgrounds including discrete Wilson lines on the Yukawa matrices and their connection to CP violation.
17128114
On Inflation in the Presence of a Gaugino Condensate
Abstract We study the effect of inflation on gaugino condensation in supergravity. Unless the Hubble scale H is significantly below the gaugino condensation scale, the gaugino condensate is a dynamical variable which cannot be integrated out. For a sufficiently high H , the gaugino condensate evolves to zero which in turn leads to dilaton/moduli destabilization. In practice, this often occurs at the Hubble rate about an order of magnitude below the gaugino condensation scale. This effect is independent of the specifics of moduli stabilization and thus places model-independent constraints on inflationary scenarios. It also applies more generally to any periods of fast expansion in the early Universe.
182123800
Characteristics of Transversal Coherent Beam Instability on the Plateau of 386-Oe Magnetic Field at the SERPUKHOV Accelerator. (Talk, in Russian)
126255062
EXPERIMENTAL STUDY OF COHERENT TRANSVERSE BEAM INSTABILITY AT THE IHEP ACCELERATOR
123386574
Experimental investigation of stochastic slow extraction from the U-70 synchrotron
The feasibility of developing a system for stochastic (noise) slow extraction from the U-70 proton synchrotron of the Institute for High Energy Physics is substantiated, and the results from its experimental testing are presented. The existing auxiliary 200-MHz RF system (accelerating frequency, 5.5–6 MHz) is used as a longitudinal kicker. This system is driven by the superposition of a deterministic (nonrandom) RF carrier and additive phase noise. The noise gives rise to longitudinal beam diffusion that forces protons into the third-order transverse extraction resonance. The technical constraints inherent in the U-70 machine are taken into account in the proposed scheme. The extraction technique is expected to provide flat-topped spills having a duration of a few seconds and a low contamination with ripple.
110736460
UPGRADING LONGITUDINAL BEAM BEHAVIOR IN IHEP BOOSTER
Operation of 1.5 GeV fast-cycling Booster proton synchrotron of IHEP has been long hampered by unwanted oscillations in bunch length. To identify the reason of such beam behavior, a dedicated beam-dynamics research program has been initiated. The scope of this activity has covered a variety of the might-be mechanisms behind — coherent instabilities, malfunction of voltage amplitude feedbacks, quality of the voltage program, etc. Ultimately, phase loop encircling the VCO has been upgraded, which resulted in a noticeably suppressed scale of both, dipole and quadrupole oscillations of beam. BEAM OBSERVATIONS Coherent oscillations in bunch length were incidentally observed during routine operation of the machine. These were monitored as a distortion of bunch shape prior to beam transfer. The process was accompanied by an occurrence of asymmetry in longitudinal density distribution. This picture had a rather uncertain cycle-to-cycle recurrence. Each time, the beam conduct was subject to improving noticeably with finer tuning the initial value of radio-frequency in the Booster. Still, a mismatch with phase-plane trajectories of the accepting ring, U70, persisted. It hampered subsequent accumulation and acceleration of a high intensity beam in U70. To this end, a dedicated R&D program was launched to study beam longitudinal oscillations through the entire cycle and elaborate technical cures against oscillations in bunch length, specifically.
218611448
A STOCHASTIC SLOW EXTRACTION SCHEME FOR U70 SYNCHROTRON
Outcomes of a feasibility study for a low-budget stochastic slow extraction system in the U70 proton synchrotron of IHEP are reported. The existing 200 MHz (spill) RF system is to be employed as a longitudinal kicker. It will be driven by a sum of a non-random RF carrier plus an additive random amplitude-modulated signal — either quadrature or in-phase, or both. A few novel solutions to be implemented in the longitudinal diffusion technique that would force protons into the conventional 3-rd order transverse extraction resonance are foreseen so as to comply with the technical constraints inherent in U70. Getting a-few-seconds-long and high-quality spills is assessed as being viable with the system in question.