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.
16019794
A Stringy Solution to the FCNC Problem
The solution to the supersymmetric FCNC problem may not have a simple field theory interpretation. Here I advocate a possibility based on string selection rules. The requirement of non--trivial Yukawa structures restricts the form of the soft terms such that the FCNC problem often does not arise.
42733826
Electric dipole moments in the limit of heavy superpartners.
Supersymmetric loop corrections induce potentially large CP-violating couplings of the Higgs bosons to nucleons and electrons that do not vanish in the limit of heavy superpartners. The Higgs-mediated CP-odd four-fermion operators are enhanced by tan((3)beta and induce electric dipole moments of heavy atoms which exceed the current experimental bounds for the electroweak scale Higgs masses and tan(beta greater, similar 10. If only the first two sfermion generations are heavy, the Higgs-mediated contributions typically dominate over the Barr-Zee type two-loop diagrams at tan(beta>30.
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.
119349560
Constraints on two-Higgs-doublet models at large tan {beta} from W and Z decays
We study constraints on type-II two-Higgs-doublet models at large tan {beta} from CERN LEP and SLD Z-pole data and from lepton universality violation in W decay. We perform a global fit and find that, in the context of Z decay, the LEP-SLD experimental values for lepton universality violation, R{sub b}, and A{sub b} all somewhat disfavor the model. Contributions from the neutral-Higgs sector can be used to constrain the scalar-pseudoscalar Higgs mass splittings. Contributions from the charged-Higgs sector allow us to constrain the charged-Higgs boson mass. For tan {beta}=100 we obtain the 1{sigma} classical (Bayesian) bounds of m{sub H{sup {+-}}}{>=}670 GeV (370 GeV) and 1{>=}m{sub h{sup 0}}/m{sub A{sup 0}}|{sub {alpha}}{sub ={beta}}=m{sub H{sup 0}}/m{sub A{sup 0}}|{sub {alpha}}{sub =0}{>=}0.68 (0.64). The 2{sigma} bounds are weak. Currently, the Fermilab Tevatron experimental limits on lepton universality violation in W decay provide no significant constraint on the Higgs sector. (c) 2000 The American Physical Society.
126255062
EXPERIMENTAL STUDY OF COHERENT TRANSVERSE BEAM INSTABILITY AT THE IHEP ACCELERATOR
182123800
Characteristics of Transversal Coherent Beam Instability on the Plateau of 386-Oe Magnetic Field at the SERPUKHOV Accelerator. (Talk, in Russian)
122053065
Coasting Beam in HERA-p Ring
This document is a report on stud ies of production/tr ansport mechanisms resulting in and of cures against a coasting beam halo observed at the HERA proton ring of DESY. Noises in the 208 MHz RF system, drift beyond RF buckets due to energy loss through synchrotron radiation of the highenergy protons and effect of adding the 52 MHz RF voltage are claimed to account for the diverse observations over the halation effect available by now. The work was performed under Attachment #63 to the Agreement between DESY (Hamburg, Germany) and IHEP (Protvino, Russia), re: Coasting Beam in HERA-p Ring, June 2000.
59025092
Decreasing transient beam loading in RF cavities of U-70 accelerator
The U-70 RF system was worked out to operate with the injector-linac at 100 MeV energy. A wide RF range was (2.6-6.1) MHz. For the U-70 injector Booster the wide RF range decreased and now it is (5.5-6.1) MHz. This fact and simplest method of changing the parameters in RF ferrite dominated cavities allow one to increase of the equivalent value of the cavity capacitance for the main frequency by about a factor of 2.7 and increase of the value of the cavity gap capacitance by about a factor of 5. The experimental investigation of the U-70 RF cavities due to the injection of bunches from the Booster into the U-70 orbit, near transition and on main flat-top is presented.
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.