Searcharxiv⌕ Search

SEARCH · Searcharxiv

Results for “hep-ex”

Search indexed arXiv papers on artificial intelligence, large language models, computer vision and robotics. Read source abstracts and follow links to arXiv.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources
arXiv2007

Heavy chiral bosons search at hadron colliders

The production of new spin-1 chiral bosons at the hadron colliders, the Fermilab Tevatron and the CERN LHC, is considered. The masses of the chiral bosons can be determined on the basis of experimental data of precise low-energy experiments, which already indicate indirectly their existence. They can explain, for example, the serious 4.5 sigma discrepancy between the measured and the predicted two pion branching ratio of the tau decay and the sign of the 3.3 sigma deviation of the muon (g-2) theoretical prediction from the experimental value. Quantitative evaluations of the various differential cross-sections of the chiral boson production at hadron colliders are made using the CalcHEP package. It is noteworthy that the Tevatron data already hint the existence of the lightest charged chiral boson with a mass around 500 GeV. New Tevatron data and the LHC results will definitely confirm or reject this indication. In the positive case the LHC would be able to discover all predicted charged and neutral chiral bosons spanning in mass up to 1 TeV.

hep-ph↗
arXiv2007

An Experiment to Search for Light Dark Matter in Low-Energy ep Scattering

Anomalous production of low-energy photons from the galactic center have fueled speculations on the nature and properties of dark matter particles. In particular, it has been proposed that light scalars may be responsible for the bulk of the matter density of the universe, and that they couple to ordinary matter through a light spin-1 boson. If this is the case, then such particles may be produced in the quasi-elastic low-energy scattering of electrons off protons. We present a proposal for an experiment to search for this process and assess its viability.

hep-ex↗
arXiv2007

Recent results from NA48

Recent results from the experiments NA48, NA48/1 and NA48/2 are presented, including: direct CP-violation and Dalitz plot slopes measurements for K+- --> 3 pi decays; pi pi scattering effects in K+- --> pi+- pi0 pi0 and Ke4 decays, as well as Ke4 form factors and branching fraction; measurements on radiative charged kaons and hyperon decays, semileptonic decays of neutral and charged kaons; KL --> pi+ pi- branching ratio and |eta+-| measurement; lepton universality check with Kl2 decays.

hep-ex↗
arXiv2007

MINOS Results, Progress and Future Prospects

The MINOS long baseline experiment has been collecting neutrino beam data since March 2005 and has accumulated 3 x 10^{20} protons-on-target (POT) to date. MINOS uses Fermilab's NuMI neutrino beam which is measured by two steel-scintillator tracking calorimeters, one at Fermilab and the other 735 km downstream, in northern Minnesota. By observing the oscillatory structure in the neutrino energy spectrum, MINOS can precisely measure the neutrino oscillation parameters in the atmospheric sector. From analysis of the first year of data, corresponding to 1.27 x 10^{20} POT, these parameters were determined to be |Δm^2_{32}|=2.74^{+0.44}_{-0.26} x 10^{-3} eV^2 and sin^2(2θ_{23})>0.87 (68% C.L.). MINOS is able to measure the neutrino velocity by comparing the arrival times of the neutrino beam in its two detectors. Using a total of 473 Far Detector events, (v-c)/c = (5.1 +/- 2.9) x 10^{-5} (68% C.L.) was measured. In addition, we report recent progress in the analysis of neutral current events and give an outline of experimental goals for the future.

hep-ex↗
arXiv2007

Interpretation of the atmospheric muon charge ratio in MINOS

MINOS is the first large magnetic detector deep underground and is the first to measure the muon charge ratio with high statistics in the region near 1 TeV.\cite{bib:adamson} An approximate formula for the muon charge ratio can be expressed in terms of $ε_π$ = 115 GeV, $ε_K$ = 850 GeV and $\ec$. The implications for K production in the atmosphere will be discussed.

hep-ex↗
arXiv2007

Results on axion physics from the CAST Experiment at CERN

Axions are expected to be produced in the sun via the Primakoff process. They may be detected through the inverse process in the laboratory, under the influence of a strong magnetic field, giving rise to X-rays of energies in the range of a few keV. Such an Axion detector is the CERN Axion Solar Telescope (CAST), collecting data since 2003. Results have been published, pushing the axion-photon coupling g$_{aγ}$ below the 10$^{-10}$ GeV$^{-1}$ limit at 95% CL, for axion masses less than 0.02 eV. This limit is nearly an order of magnitude lower than previous experimental limits and surpassed for the first time limits set from astrophysical arguments based on the energy-loss concept. The experiment is currently exploring axion masses in the range of 0.02 eV $< m_a <$ 1.1 eV. In the next run, currently under preparation, the axion mass explored will be extended up to the limit of 1.1 eV, testing for the first time the region of theoretical axion models with the axion helioscope method.

hep-ex↗
arXiv2007

Electroweak measurements at the Tevatron

The increasing size of the data samples recorded by the CDF and DO experiments at the Tevatron enables studies of a wide range of processes involving the electroweak bosons W and Z. Single boson production is now looked at in terms of differential cross sections such as rapidity or transverse momentum dependence. Diboson production cross-sections are several orders of magnitude smaller than single boson production cross-sections, but all combinations Wgamma, Zgamma, WW and WZ have been observed. ZZ production is expected at a rate just below the observation threshold with current data sample sizes, but this channel is expected to be accessible to the Tevatron experiments soon.

hep-ex↗
arXiv2007

Exclusive rho0 electroproduction

Exclusive rho0 electroproduction at HERA has been studied with the ZEUS detector, using 120 pb{-1} integrated luminosity, in the kinematic range of photon virtuality of 2 < Q2 < 160 GeV2, and gamma* p center-of-mass energy of 32 < W < 180 GeV. The results include the Q2 and W dependence of the gamma* p --> rho0 p cross section and the distribution of the squared-four-momentum transfer to the proton, t. Also included is the ratio of longitudinal to transverse gamma* p cross section as a function of Q2, W and t. Finally, the effective Pomeron trajectory was extracted. The results are compared to various theoretical predictions, none of which are able to reproduce all the features of the data.

hep-ex↗
arXiv2007

Measurements of Top Properties at the Tevatron

The large data samples of thousands of top events collected at the Tevatron experiments CDF and D0 allow for a variety of measurements to analyze the properties of the top quark. Guided by the question "Is the top quark observed at the Tevatron really the top quark of the standard model,'' we present Tevatron analyses studying the top production mechanism including resonant $t\bar{t}$ production, the V-A structure of the $t\to Wb$ decay vertex, the charge of the top quark, and single-top production via flavor-changing neutral currents.

hep-ex↗
arXiv2007

Applying Extensive Air Shower Universality to Ground Detector Data

Air shower universality states that the electromagnetic part of hadron-induced extensive air showers (EAS) can be completely described in terms of the primary energy and shower age. In addition, simulations show that the muon part is well characterized by an overall normalization which depends on the primary particle and hadronic interaction model. We investigate the consequences of EAS universality for ground arrays, which sample EAS at large core distances, and show how universality can be used to experimentally determine the muon content as well as the primary energy of cosmic ray air showers in a model-independent way.

astro-ph↗
arXiv2007

Direct CP Violation in B Decays

We discuss several aspects of direct CP asymmetries in B decays, which are very useful in spite of hadronic uncertainties in asymmetry calculations. 1) Asymmetries in decays to $D^{(*)}K^{(*)}$, $π^+π^-, ρ^+ρ^-$, providing precision tests for the CKM phase $γ$. 2) Null tests in $B^+\to J/ψK^+, π^+π^0$, where a nonzero asymmetry provides evidence for New Physics. 3) Isospin and broken flavor SU(3) relations among CP asymmetries in $B\to Kπ, ππ$ predicting $A_{CP}(B^0\to K^0π^0)$ and $A_{CP}(B^0\to π^0π^0)$. 4) The significance of $A_{CP}(B^0\to K^+π^-)\ne A_{CP}(B^+\to K^+π^0)$. 5) A potentially stringent constraint on $γ$ from $A_{CP}(B^+\to K^+π^0)$ and $R_c\equiv 2Γ(B^+\to K^+π^0)/Γ(B^+\to K^0π^+)$. 6) The role of direct CP asymmetries in $b\to s\bar qq$ decays for studying the origin of potential New Physics.

hep-ph↗
arXiv2007

Searching for H->WW(*) and Other Diboson Final States at CDF

We report searches for standard model (SM) Higgs production decaying to WW(*) and continuum ZZ production in the two charged lepton and two neutrino final states. The data were collected with the CDF II detector at the Fermilab Tevatron and correspond to an integrated luminosity of 1.1^fb-1. In order to separate the processes contributing to the final state, event probabilities calculated using the leading order differential cross-sections were used to construct a likelihood ratio discriminant. The observed (median expected) 95% C.L. upper limit for sigma(H->WW^(*)) with 160 GeV/c^2 mass hypothesis is 1.3 (1.8) pb which corresponds to 3.4 (4.8) times the SM prediction at next-to-next-to-leading logarithmic level (NNLL) calculation. The significance of the observed ZZ signal is 1.9 sigma and the 95% C.L. upper limit is 3.4 pb which is consistent with the next-to-leading order (NLO) calculation of 1.4+/-0.1 pb.

hep-ex↗
arXiv2007

Longitudinal Spin Measurements with Inclusive Hadrons in Polarized p+p Collisions at 200 GeV

We present measurements of the double longitudinal spin asymmetries for inclusive pi0 and pi+(-) production in polarized p+p collisions at sqrt(s) = 200 GeV at mid-rapidity with the STAR detector from the 2005 RHIC run. These measurements are used to access Delta G/G, the gluon polarization in the proton. The observed unpolarized inclusive cross sections show good agreement with NLO pQCD calculations. The double longitudinal spin asymmetries are compared to NLO pQCD calculations based on different assumptions for the gluon polarization in the nucleon to provide constraints on Delta G/G. At the present level of statistics the measured asymmetries disfavor a large positive gluon polarization, but cannot yet distinguish between other scenarios.

hep-ex↗
arXiv2007

New Heavy Quark Baryons

During the past year many interesting results were published in heavy quark baryon spectroscopy. In addition to several refined measurements, new states were directly observed both in the charm and the bottom sector. In this paper we review recent results on heavy quark baryons from B-factories and Tevatron experiments.

hep-ex↗
arXiv2007

Searches in Photon and Jet States

We present recent results from the Collider Detector at Fermilab (CDF) and D0 experiments using data from proton-antiproton collisions with sqrt(s) = 1.96 TeV at Run II of the Fermilab Tevatron. New physics may appear in events with high transverse momentum objects, including photons and quark or gluon jets. The results described here are of signature-based searches and model-based searches probing supersymmetry, leptoquarks, 4th generation quarks, and large extra dimensions.

hep-ex↗