Disentangling soft and collinear effects in QCD parton showers
Not Available
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
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Search for CP Violation in the Decay D+/- to Ks pi+/-
We report on a search for CP violation in the decay D{sup {+-}} {yields} K{sub S}{sup 0}{pi}{sup {+-}} using a data set corresponding to an integrated luminosity of 469 fb{sup -1} collected with the BABAR detector at the PEP-II asymmetric energy e{sup +}e{sup -} storage rings. The CP-violating decay rate asymmetry A{sub CP} is determined to be (-0.44 {+-} 0.13(stat) {+-} 0.10(syst))%, consistent with zero at 2.7 {sigma} and with the standard model prediction of (-0.332 {+-} 0.006)%. This is currently the most precise measurement of this parameter.
43 PARTICLE ACCELERATORS↗
Novel explanation of charmoniumlike structure in e{sup +}e{sup -}{yields}{psi}(2S){pi}{sup +}{pi}{sup -}
We first present a nonresonant description to charmoniumlike structure Y(4360) in the {psi}(2S){pi}{sup +}{pi}{sup -} invariant mass spectrum of the e{sup +}e{sup -}{yields}{psi}(2S){pi}{sup +}{pi}{sup -} process. The Y(4360) structure is depicted well by the interference effect of the production amplitudes of e{sup +}e{sup -}{yields}{psi}(2S){pi}{sup +}{pi}{sup -} via the intermediate charmonia {psi}(4160)/{psi}(4415) and direct e{sup +}e{sup -} annihilation into {psi}(2S){pi}{sup +}{pi}{sup -}. This fact shows that Y(4360) is not a genuine resonance, which naturally explains why Y(4360) was only reported in its hidden-charm decay channel {psi}(2S){pi}{sup +}{pi}{sup -} and was not observed in the exclusive open-charm decay channel or R-value scan.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Thrust at N 3 LL with power corrections and a precision global fit for α s (m Z )
Not Available
Abbate, Riccardo↗
Consequences of the BABAR and KLOE e{sup +}e{sup -}{yields}{pi}{sup +}{pi}{sup -} data for the determination of model-dependent {rho}-{omega} mixing effects in {Pi}{sub {rho}{omega}}(m{sub {rho}}{sup 2}) and (g-2){sub {mu}}
We update our analysis of {rho}-{omega} mixing effects in the pion form factor to incorporate the recently published BABAR and KLOE e{sup +}e{sup -}{yields}{pi}{sup +}{pi}{sup -} cross sections. Implications for {tau}-decay-based standard model estimates of the leading order hadronic contribution to the muon anomalous magnetic moment, and for the extraction of the off-diagonal vector meson self-energy matrix element, {Pi}{sub {rho}{omega}}(m{sub {rho}}{sup 2}), are discussed.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Global constraints on muon-neutrino nonstandard interactions
The search for new interactions of neutrinos beyond those of the standard model may help to elucidate the mechanism responsible for neutrino masses. Here, we combine existing accelerator neutrino data with restrictions coming from a recent atmospheric neutrino data analysis in order to lift parameter degeneracies and improve limits on new interactions of muon neutrinos with quarks. In particular, we reconsider the results of the E-815 experiment at Fermilab (NuTeV) in view of a new evaluation of its systematic uncertainties. We find that, although constraints for muon neutrinos are better than those applicable to tau or electron neutrinos, they lie at the fewx10{sup -2} level, not as strong as previously believed. We briefly discuss prospects for further improvement.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Study of two-photon corrections in the pp{yields}e{sup +}e{sup -} process: Hard rescattering mechanism
We investigate the two-photon corrections to the process pp{yields}e{sup +}e{sup -} at large momentum transfer, aimed to access the timelike nucleon form factors. We estimate the two-photon corrections using a hard rescattering mechanism, which has already been used to calculate the corresponding corrections to elastic electron-proton scattering. Using different nucleon distribution amplitudes, we find that the two-photon corrections to the pp{yields}e{sup +}e{sup -} cross sections in the momentum transfer range 5-30 GeV{sup 2} is below the 1% level.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Vector bosons escaping from the brane: e{sup +}e{sup -}{yields}{gamma}+ nothing
We consider phenomenological consequences of the RS2-n model with an infinite extra dimension, namely, the production, in high-energy collisions, of a photon or Z boson escaping from our brane in association with a photon remaining on the brane. This would show up as process e{sup +}e{sup -}{yields}{gamma}+ nothing. We compare the signal with the standard model background coming from e{sup +}e{sup -}{yields}{gamma}{bar {nu}}{nu}. We also make a comparison with e{sup +}e{sup -}{yields}{gamma}+ nothing in the Arkani-Hamed-Dimopoulos-Dvali model.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
N-mode coherence in collective neutrino oscillations
We study two-flavor neutrino oscillations in a homogeneous and isotropic ensemble under the influence of neutrino-neutrino interactions. For any density there exist forms of collective oscillations that show self-maintained coherence. They can be classified by a number N of linearly independent functions that describe all neutrino modes as linear superpositions. What is more, the dynamics is equivalent to another ensemble with the same effective density, consisting of N modes with discrete energies E{sub i} with i=1,...,N. We use this equivalence to derive the analytic solution for two-mode (bimodal) coherence, relevant for spectral-split formation in supernova neutrinos.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Neutrino-impact ionization of atoms in searches for neutrino magnetic moment
The ionization of atomic electrons by scattering of neutrinos is revisited. This process is the one studied in the experimental searches for a neutrino magnetic moment using germanium detectors. Current experiments are sensitive to the ionization energy comparable with the atomic energies, and the effects of the electron binding should be taken into account. We find that the so-called stepping approximation to the neutrino-impact ionization is in fact exact in the semiclassical limit and also that the deviations from this approximation are very small already for the lowest bound Coulomb states. We also consider the effects of electron-electron correlations and argue that the resulting corrections to the ionization of independent electrons are quite small. In particular, we estimate that in germanium these are at a 1% level at the energy transfer down to a fraction of keV. Exact sum rules are also presented as well as analytical results for a few lowest hydrogenlike states.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Neutrino spectral split in core-collapse supernovae: A magnetic resonance phenomenon
A variety of neutrino flavor conversion phenomena occur in core-collapse supernova, due to the large neutrino density close to the neutrinosphere, and the importance of the neutrino-neutrino interaction. Three different regimes have been identified so far, usually called the synchronization, the bipolar oscillations, and the spectral split. Using the formalism of polarization vectors, within two flavors, we focus on the spectral split phenomenon and we show for the first time that the physical mechanism underlying the neutrino spectral split is a magnetic resonance phenomenon. In particular, we show that the precession frequencies fulfill the magnetic resonance conditions. Our numerical calculations show that the neutrino energies and the location at which the resonance takes place in the supernova coincide well with the neutrino energies at which a spectral swap occurs. The corresponding adiabaticity parameters present spikes at the resonance location.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Inclusive B-meson production at the LHC in the general-mass variable-flavor-number scheme
We calculate the next-to-leading-order cross section for the inclusive production of B mesons in pp collisions in the general-mass variable-flavor-number scheme, an approach that takes into account the finite mass of the b quarks. We use realistic evolved nonperturbative fragmentation functions obtained from fits to e{sup +}e{sup -} data and compare our results for the transverse-momentum and rapidity distributions at a center-of-mass energy of 7 TeV with recent data from the CMS Collaboration at the CERN LHC. We find good agreement, in particular, at large values of p{sub T}.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Lepton number violation in top quark and neutral B meson decays
Lepton number violation can be induced by Majorana neutrinos in four-body decays of the neutral B meson and the top quark. We study the effects of Majorana neutrinos in these |{Delta}L|=2 decays in a scenario where a single heavy neutrino can enhance the amplitude via the resonant mechanism. Using current bounds on heavy neutrino mixings, the most optimistic branching ratios turn out to be at the level of 10{sup -6} for B{sup 0}{yields}D{sup +}e{sup -}e{sup -}{pi}{sup +} and t{yields}bl{sup +}l{sup +}W{sup -} decays. Searches for these lepton number violation decays at future facilities can provide complementary constraints on masses and mixings of Majorana neutrinos.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Publisher's Note: Study of radiative bottomonium transitions using converted photons [Phys. Rev. D 84, 072002 (2011)]
No abstract prepared.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Probing new spin-independent interactions through precision spectroscopy in atoms with few electrons
The very high precision of current measurements and theory predictions of spectral lines in few-electron atoms allows us to efficiently probe the existence of exotic forces between electrons, neutrons and protons. We investigate here the sensitivity to new spin-independent interactions in transition frequencies (and their isotopic shifts) of hydrogen, helium and some heliumlike ions. We find that present data probe new regions of the force-carrier couplings to electrons and neutrons around the MeV mass range. We also find that, below few keV, the sensitivity to the electron coupling in precision spectroscopy of helium and positronium is comparable to that of the anomalous magnetic moment of the electron. Finally, we interpret our results in the dark-photon model where a new gauge boson is kinetically mixed with the photon. There, we show that helium transitions, combined with the anomalous magnetic moment of the electron, provide the strongest indirect bound from laboratory experiments above 100 keV.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
Wave dispersion in a counterstreaming, relativistic thermal, magnetized, electron-positron plasma
The dispersion equation is analyzed for waves in a strongly magnetized, electron-positron plasma in which counterstreaming electrons and positrons have a relativistic thermal distribution in their respective rest frames, for propagation parallel to the magnetic field. We derive the response tensor for the medium, demonstrate the dispersion curves for different temperatures, and discuss the differences from the cold-plasma case. Application to the case of pulsar magnetospheres is discussed.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
Lorentz-Abraham-Dirac versus Landau-Lifshitz radiation friction force in the ultrarelativistic electron interaction with electromagnetic wave (exact solutions)
When the parameters of electron-extreme power laser interaction enter the regime of dominated radiation reaction, the electron dynamics changes qualitatively. The adequate theoretical description of this regime becomes crucially important with the use of the radiation friction force either in the Lorentz-Abraham-Dirac form, which possesses unphysical runaway solutions, or in the Landau-Lifshitz form, which is a perturbation valid for relatively low electromagnetic wave amplitude. The goal of the present paper is to find the limits of the Landau-Lifshitz radiation force applicability in terms of the electromagnetic wave amplitude and frequency. For this, a class of the exact solutions to the nonlinear problems of charged particle motion in the time-varying electromagnetic field is used.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
First Glances at the Transversity Parton Distribution through Dihadron Fragmentation Functions
We present first observations of the transversity parton distribution based on an analysis of pion-pair production in deep-inelastic scattering off transversely polarized targets. The extraction of transversity relies on the knowledge of dihadron fragmentation functions, which we take from electron-positron annihilation measurements. This is the first attempt to determine the transversity distribution in the framework of collinear factorization.
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗