Diffraction as a critical ingredient in soft scattering
The roll of diffraction in the formulation of soft scattering is investigated aiming to assess the resent SD TOTEM results.
hep-ex↗
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Thorium isomer for radiative emission of neutrino pair
It is proposed to use the isomer ionic ground state $^{229m}$Th$^{4+}$ embedded in transparent crystals for precision determination of unknown neutrino parameters. Isolation from solid environment of the proposed nuclear process, along with available experimental techniques of atomic physics, has a great potentiality for further study.
hep-ex↗
Status Report of LPCC Forward Physics Group
We report here about activities of newly formed working group aiming to define a forward and diffractive physics program at the LHC for the years to come.
physics.acc-ph↗
Results on ultra-peripheral interactions in Pb-Pb and p-Pb collisions in ALICE
Ultra-relativistic heavy ions generate strong electromagnetic fields which offer the possibility to study $γ$-nucleus and $γ$-proton interactions at the LHC in the so called ultra-peripheral collisions (UPC). Here we report ALICE results on J/psi photoproduction measured in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 2.76 TeV and in p-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV.
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Searches for rare and forbidden kaon decays at the NA62 experiment at CERN
The decay $K^+ \to π^+ν\barν$ is highly suppressed in the Standard Model (SM), while its rate can be predicted with minimal theoretical uncertainty. The branching ratio (BR) for this decay is thus a sensitive probe of the flavor sector of the SM; its measurement, however, is a significant experimental challenge. The primary goal of the NA62 experiment is to measure ${\rm BR}(K^+ \to π^+ν\barν)$ with $\sim$10% precision. This will require the observation of $10^{13}$ $K^+$ decays in the experiment's fiducial volume, as well as the use of high-performance systems for precision tracking, particle identification, and photon vetoing. These aspects of the experiment will also allow NA62 to carry out a rich program of searches for lepton flavor and/or number violating $K^+$ decays. Part of the experimental apparatus was commissioned during a technical run in 2012; installation continues and data taking is expected to begin in late 2014. The physics prospects and the status of the NA62 experiment are reviewed.
hep-ex↗
Search for narrow six-quark states in the reactions $γd\to πγnn$
We study the reactions $γd\toπγNN$ with the aim to search for six-quark states, the decay of which into two nucleons is forbidden by the Pauli exclusion principle. These states with the masses $M<2m_N+m_π$ should mainly decay by emitting a photon. This is a new class of metastable six-quark states with the decay widths $<< 1$keV. The recent experiment at Proton Linear Accelerator of INR (Moscow) suggests a possibility of the existence of such states with masses 1904, 1926, and 1942 MeV. The proposed experiment at MAMI-C could provide an unique opportunity to observe such dibaryon states in mass region up to 2000 MeV and determine their masses and quantum numbers.
nucl-ex↗
Snowmass CF1 Summary: WIMP Dark Matter Direct Detection
As part of the Snowmass process, the Cosmic Frontier WIMP Direct Detection subgroup (CF1) has drawn on input from the Cosmic Frontier and the broader Particle Physics community to produce this document. The charge to CF1 was (a) to summarize the current status and projected sensitivity of WIMP direct detection experiments worldwide, (b) motivate WIMP dark matter searches over a broad parameter space by examining a spectrum of WIMP models, (c) establish a community consensus on the type of experimental program required to explore that parameter space, and (d) identify the common infrastructure required to practically meet those goals.
hep-ex↗
Neutrino induced charged-current coherent $ρ$ production
We present the latest results of coherent $ρ$ (Coh$ρ$) production using the large data set collected by the NOMAD detector in which the momenta, charges, and photons are precisely measured. We discuss the application of using Coh$ρ$ process to constrain the neutrino flux with the proposed Long-Baseline Neutrino Experiment Near Detector, the high resolution Straw Tube Tracker.
hep-ex↗
Neutron-Antineutron Oscillations: A Snowmass 2013 White Paper
This paper summarizes discussions of the theoretical developments and the studies performed by the NNbarX collaboration for the 2013 Snowmass Community Summer Study.
hep-ex↗
Dark Matter in the Coming Decade: Complementary Paths to Discovery and Beyond
In this Report we discuss the four complementary searches for the identity of dark matter: direct detection experiments that look for dark matter interacting in the lab, indirect detection experiments that connect lab signals to dark matter in our own and other galaxies, collider experiments that elucidate the particle properties of dark matter, and astrophysical probes sensitive to non-gravitational interactions of dark matter. The complementarity among the different dark matter searches is discussed qualitatively and illustrated quantitatively in several theoretical scenarios. Our primary conclusion is that the diversity of possible dark matter candidates requires a balanced program based on all four of those approaches.
hep-ph↗
Dark Sectors and New, Light, Weakly-Coupled Particles
Dark sectors, consisting of new, light, weakly-coupled particles that do not interact with the known strong, weak, or electromagnetic forces, are a particularly compelling possibility for new physics. Nature may contain numerous dark sectors, each with their own beautiful structure, distinct particles, and forces. This review summarizes the physics motivation for dark sectors and the exciting opportunities for experimental exploration. It is the summary of the Intensity Frontier subgroup "New, Light, Weakly-coupled Particles" of the Community Summer Study 2013 (Snowmass). We discuss axions, which solve the strong CP problem and are an excellent dark matter candidate, and their generalization to axion-like particles. We also review dark photons and other dark-sector particles, including sub-GeV dark matter, which are theoretically natural, provide for dark matter candidates or new dark matter interactions, and could resolve outstanding puzzles in particle and astro-particle physics. In many cases, the exploration of dark sectors can proceed with existing facilities and comparatively modest experiments. A rich, diverse, and low-cost experimental program has been identified that has the potential for one or more game-changing discoveries. These physics opportunities should be vigorously pursued in the US and elsewhere.
hep-ph↗
Searching a Dark Photon with HADES
We present a search for the e+e- decay of a hypothetical dark photon, also names U vector boson, in inclusive dielectron spectra measured by HADES in the p (3.5 GeV) + p, Nb reactions, as well as the Ar (1.756 GeV/u) + KCl reaction. An upper limit on the kinetic mixing parameter squared epsilon^{2} at 90% CL has been obtained for the mass range M(U) = 0.02 - 0.55 GeV/c2 and is compared with the present world data set. For masses 0.03 - 0.1 GeV/c^2, the limit has been lowered with respect to previous results, allowing now to exclude a large part of the parameter region favoured by the muon g-2 anomaly. Furthermore, an improved upper limit on the branching ratio of 2.3 * 10^{-6} has been set on the helicity-suppressed direct decay of the eta meson, eta-> e+e-, at 90% CL.
hep-ex↗
New Particles Working Group Report of the Snowmass 2013 Community Summer Study
This report summarizes the work of the Energy Frontier New Physics working group of the 2013 Community Summer Study (Snowmass).
hep-ex↗
Search for exotic heavy top and bottom quark partners with CMS
We present searches for massive top and bottom quark partners at CMS using LHC pp collision data collected at centre-of-mass energy $\sqrt{s} = 8$ TeV. Such partners can be found in models predicting vector-like quarks to solve the hierarchy problem and stabilize the Higgs boson mass. The searches span a range of final states containing several lepton and jet multiplicities, and limits were set on mass and production cross sections as a function of branching ratios.
hep-ex↗
Top-quark Pair Production in a Running Mass Scheme
Between the Tevatron and LHC, top-quark physics is now becoming an area for precision physics. This has lead to an increase in theoretical activity to match the experimental accuracy of top anti-top production. We discuss the difficulty in properly defining the top-quark mass as measured by experiments and present results for differential distributions of top-quark pair production in a running mass scheme. The use of such a scheme shows better convergence in the perturbative expansion and improves the scale dependence as opposed to the typical on-shell scheme.
hep-ph↗
Observation of $Z_c(3900)$ both by BESIII and Belle
Using $525$ pb$^{-1}$ data collected with the BESIII detector at $e^+e^-$ central-of-mass energy 4.26 GeV, the BESIII Collaboration observed a charged charmoniumlike state $Z_c(3900)\toπ^{\pm}J/ψ$ with mass $M[Z_c(3900)]=3899.0\pm 3.6 \pm 4.9$ MeV/c$^2$, and width $Γ[Z_c(3900)]=46\pm 10 \pm 20$ MeV. The significance of this state was estimated to be $>8σ$ in all kinds of systematic tests. Using $967$ fb$^{-1}$ data recorded by the Belle detector on or near $Υ(nS)$, n=1, 2, $\cdots$, 5 resonances, the $e^+e^- \to π^+π^-J/ψ$ process has been studied through initial-state-radiation (ISR) method. Except for the $Y(4260)$ resonance, an intermediate state $Z(3900)^{\pm}$ has been observed in the $π^{\pm}J/ψ$ mass spectrum, with significance $>5.2σ$. The measured mass $M[Z(3900)^{\pm}]=3894.5\pm6.6\pm4.5$ MeV/c$^2$ and width $Γ[Z(3900)^{\pm}]=63\pm24\pm26$ MeV, shows good agreement with the BESIII measurement within errors, which means $Z_c(3900)$ and $Z(3900)^{\pm}$ is the same state.
hep-ex↗
T symmetry invariance tests in neutral meson decays
We outline how the time-reversal symmetry T can be systematically used to test the Kobayashi-Maskawa mechanism embedded in the CKM matrix using pairs of B mesons created at the Upsilon(4S) and pairs of D mesons from psi(3770).
hep-ph↗
Results on conventional and exotic charmonium at BaBar
The B factories provide a unique playground for studying the properties of conventional and exotic charmonium states. We present recent results in initial state radiation and two-photon fusion, obtained using the full data set collected by the BaBar experiment. Amongst BaBar 's harvest presented in this talk, the determination of the quantum numbers of the X(3915) resonance, a body of concording evidence pointing to JPC = 1++ for the X(3872), and updates on the family of the Y resonance to the full integrated luminosity.
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