High Energy Physics - Experiment

New submissions

[ total of 20 entries: 1-20 ]
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New submissions for Thu, 23 Nov 17

[1]
Title: Search for gauge-mediated supersymmetry in events with at least one photon and missing transverse momentum in pp collisions at $\sqrt{s} =$ 13 TeV
Comments: Submitted to Phys. Lett. B. All the figures and tables can be found at this http URL (CMS Public Pages)
Subjects: High Energy Physics - Experiment (hep-ex)

A search for gauge-mediated supersymmetry (SUSY) in final states with photons and large missing transverse momentum is presented. The data sample of pp collisions at $\sqrt{s} =$ 13 TeV was collected with the CMS detector at the CERN LHC and corresponds to an integrated luminosity of 35.9 fb$^{-1}$. Data are compared with models in which the lightest neutralino has bino- or wino-like components, resulting in decays to photons and gravitinos, where the gravitinos escape detection. The event selection is optimized for both electroweak (EWK) and strong production SUSY scenarios. The observed data are consistent with standard model predictions, and limits are set in the context of a general gauge mediation model in which gaugino masses up to 980 GeV are excluded at 95% confidence level. Gaugino masses below 780 and 950 GeV are excluded in two simplified models with EWK production of mass-degenerate charginos and neutralinos. Stringent limits are set on simplified models based on gluino and squark pair production, excluding gluino (squark) masses up to 2100 (1750) GeV depending on the assumptions made for the decay modes and intermediate particle masses. This analysis sets the highest mass limits to date in the studied EWK models, and in the considered strong production models when the mass difference between the gauginos and the squarks or gluinos is small.

[2]
Title: Measurement of the multi-TeV neutrino cross section with IceCube using Earth absorption
Comments: Preprint version of Nature paper 10.1038/nature24459
Subjects: High Energy Physics - Experiment (hep-ex); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Experiment (nucl-ex)

Neutrinos interact only very weakly, so they are extremely penetrating. However, the theoretical neutrino-nucleon interaction cross section rises with energy such that, at energies above 40 TeV, neutrinos are expected to be absorbed as they pass through the Earth. Experimentally, the cross section has been measured only at the relatively low energies (below 400 GeV) available at neutrino beams from accelerators \cite{Agashe:2014kda, Formaggio:2013kya}. Here we report the first measurement of neutrino absorption in the Earth, using a sample of 10,784 energetic upward-going neutrino-induced muons observed with the IceCube Neutrino Observatory. The flux of high-energy neutrinos transiting long paths through the Earth is attenuated compared to a reference sample that follows shorter trajectories through the Earth. Using a fit to the two-dimensional distribution of muon energy and zenith angle, we determine the cross section for neutrino energies between 6.3 TeV and 980 TeV, more than an order of magnitude higher in energy than previous measurements. The measured cross section is $1.30^{+0.21}_{-0.19}$ (stat.) $^{+0.39}_{-0.43}$ (syst.) times the prediction of the Standard Model \cite{CooperSarkar:2011pa}, consistent with the expectation for charged and neutral current interactions. We do not observe a dramatic increase in the cross section, expected in some speculative models, including those invoking new compact dimensions \cite{AlvarezMuniz:2002ga} or the production of leptoquarks \cite{Romero:2009vu}.

[3]
Title: Search for $t\bar{t}H$ and $tH$ production with $H\to γγ$ at $\sqrt{s}$ = 13 TeV with the ATLAS experiment
Authors: Isabel Nitsche (for the ATLAS Collaboration)
Comments: 4 pages, 2 figures, TOP2017 conference
Subjects: High Energy Physics - Experiment (hep-ex)

The measurement of the Yukawa coupling of the top quark is one important goal of particle physics after the discovery of the Higgs boson. There are two processes that offer the possibility to directly measure the Yukawa coupling of the top quark at the LHC. These are the production of a top-antitop-quark pair in association with a Higgs boson via the strong interaction ($t\bar{t}H$) and the electroweak production of a single top quark and a Higgs boson ($tH$). In the Standard Model, the cross section for $tH$ production is much smaller than the cross section for $t\bar{t}H$ production as there is a destructive interference between diagrams where the Higgs boson is radiated off a top quark and diagrams where it is radiated off a $W$ boson. Despite the reduced cross section, this interference provides additional sensitivity to the sign of the Yukawa coupling.
The considered Higgs boson decay into photons is promising due to the good energy resolution of the photons and the relatively small backgrounds. But it is also challenging due to the small branching ratio.
The analysis strategy and the latest results on the search for $t\bar{t}H/tH$ production in the diphoton channel at the ATLAS experiment are presented.

[4]
Title: Measurement of the absolute branching fraction of $D_{s0}^{*\pm}(2317)\to π^0 D_{s}^{\pm}$
Subjects: High Energy Physics - Experiment (hep-ex)

The process $e^+ e^- \to D_{s}^{*+} D_{s0}^{*-}(2317)+c.c.$ is observed for the first time with the data sample of 567~pb$^{-1}$ collected with the BESIII detector operating at the BEPCII collider at a center-of-mass energy $\sqrt{s} = 4.6$~GeV. The statistical significance of the $D_{s0}^{*-}(2317)$ signal is $5.8\sigma$ and the mass is measured to be ($2318.3\pm 1.2\pm 1.2$)~MeV/$c^{2}$. The absolute branching fraction $\mathcal{B}(D_{s0}^{*-}(2317)\to \pi^0 D_{s}^{-})$ is measured as $1.00^{+0.00}_{-0.14}\pm 0.14$ for the first time. The uncertainties are statistical and systematic, respectively.

[5]
Title: A measurement of the soft-drop jet mass in pp collisions at $\sqrt{s} = 13$ TeV with the ATLAS detector
Comments: 15 pages plus author list + cover pages (33 pages total), 4 figures, submitted to PRL, All figures including auxiliary figures are available at this https URL
Subjects: High Energy Physics - Experiment (hep-ex)

Calculations of jet substructure observables that are accurate beyond leading-logarithm accuracy have recently become available. Such observables are significant not only for probing the collinear regime of QCD that is largely unexplored at a hadron collider, but also for improving the understanding of jet substructure properties that are used in many studies at the Large Hadron Collider. This Letter documents a measurement of the first jet substructure quantity at a hadron collider to be calculated at next-to-next-to-leading-logarithm accuracy. The normalized, differential cross-section is measured as a function of $log_{10}{\rho^2}$, where $\rho$ is the ratio of the soft-drop mass to the ungroomed jet transverse momentum. This quantity is measured in dijet events from 32.9 fb$^{-1}$ of $\sqrt{s}=13$ TeV proton-proton collisions recorded by the ATLAS detector. The data are unfolded to correct for detector effects and compared to precise QCD calculations and leading-logarithm particle-level Monte Carlo simulations.

Cross-lists for Thu, 23 Nov 17

[6]  arXiv:1711.08023 (cross-list from hep-ph) [pdf, other]
Title: Automated QCD and Electroweak Corrections with Sherpa
Authors: Steffen Schumann
Comments: proceedings for International Workshop on Top Quark Physics, Braga, Portugal, September 17-22, 2017
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)

Precise theoretical predictions are vital for the interpretation of Standard Model measurements and facilitate conclusive searches for New Physics phenomena at the LHC. In this contribution I highlight some of the ongoing efforts in the framework of the Sherpa event generator to provide accurate and realistic simulations of Standard Model production processes. This includes the automated evaluation of NLO QCD and NLO EW corrections and their consistent consideration in the parton-shower evolution of scattering events. Particular emphasis is given to examples and applications involving the production of top quarks.

[7]  arXiv:1711.08088 (cross-list from hep-ph) [pdf, ps, other]
Title: Hadron tomography by generalized distribution amplitudes in pion-pair production process $γ^* γ\rightarrow π^0 π^0$ and gravitational form factors for pion
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex); High Energy Physics - Lattice (hep-lat); Nuclear Theory (nucl-th)

Hadron tomography can be investigated by three-dimensional structure functions such as generalized parton distributions (GPDs), transverse-momentum-dependent parton distributions, and generalized distribution amplitudes (GDAs). Here, we extract the GDAs, which are $s$-$t$ crossed quantities of the GPDs, from cross-section measurements of hadron-pair production process $\gamma^* \gamma \rightarrow \pi^0 \pi^0$ at KEKB. This work is the first attempt to obtain the GDAs from the actual experimental data. The GDAs are expressed by a number of parameters and they are determined from the data of $\gamma^* \gamma \rightarrow \pi^0 \pi^0$ by including intermediate scalar- and tensor-meson contributions to the cross section. Our results indicate that the dependence of parton-momentum fraction $z$ in the GDAs is close to the asymptotic one. The timelike gravitational form factors $\Theta_1$ and $\Theta_2$ are obtained from our GDAs, and they are converted to the spacelike ones by the dispersion relation. From the spacelike $\Theta_1$ and $\Theta_2$, gravitational densities of the pion are calculated. Then, we obtained the mass (energy) radius and the mechanical (pressure and shear force) radius from $\Theta_2$ and $\Theta_1$, respectively. They are calculated as $\sqrt {\langle r^2 \rangle_{\text{mass}}} =0.56 \sim 0.69$ fm, whereas the mechanical radius is larger $\sqrt {\langle r^2 \rangle_{\text{mech}}} =1.45 \sim 1.56$ fm. This is the first report on the gravitational radius of a hadron from actual experimental measurements. It is interesting to find the possibility that the gravitational mass and mechanical radii could be different from the experimental charge radius $\sqrt {\langle r^2 \rangle_{\text{charge}}} =0.672 \pm 0.008$ fm for the charged pion. There is a byproduct from our analysis that $f_0 (980)$ is not likely to be a $q\bar q$-type meson in comparison with the KEKB data.

[8]  arXiv:1711.08205 (cross-list from hep-ph) [pdf, ps, other]
Title: Momentum transfer dependence of the hadron GPDs and Compton form factors
Authors: O.V. Selyugin
Comments: 6 pages; 8 figures; Talk on the XVII Workshop "High Energy Spin Physics - DSPIN-17", Dubna, Russis, September 11-15 (2017)
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)

The generalized parton distributions (GPDs) of the meson and nucleon at small and large values of the momentum transfer were determined on the basis of the comparative analysis of different sets of experimental data of electromagnetic form factors of the proton and neutron, using the different sets of the parton distribution functions (PDFs). As a result, different form factors of the nucleons and meson were calculated. The t-dependence of these form factors was checked up in the description of the nucleon-nucleon and meson-nucleon elastic scattering and the differential cross sections of the real Compton scattering.

[9]  arXiv:1711.08213 (cross-list from hep-ph) [pdf, ps, other]
Title: Tetraquark mixing framework for isoscalar resonances in light mesons
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex); Nuclear Theory (nucl-th)

Recently, a tetraquark mixing framework has been proposed for light mesons and applied more or less successfully to the isovector resonances, $a_0(980), a_0(1450)$, as well as to the isodoublet resonances, $K^*_0(800), K^*_0(1430)$. In this work, we present a more extensive view on the mixing framework and extend this to the isoscalar resonances, $f_0 (500)$, $f_0(980)$, $f_0 (1370)$, $f_0(1500)$. Tetraquarks in this framework can have two spin configurations containing either spin-0 diquark or spin-1 diquark and each configuration forms a nonet in flavor space. The two spin configurations are found to mix strongly through the color-spin interactions. Their mixtures, which diagonalize the hyperfine masses, can generate the physical resonances constituting the two nonets, which, in fact, coincide roughly with the experimental observation. We identify that $f_0 (500)$, $f_0(980)$ are the isoscalar members in the light nonet, and $f_0 (1370)$, $f_0(1500)$ are the similar members in the heavy nonet. This means that the spin configuration mixing, as it relates the corresponding members in the two nonets, can generate $f_0 (500), f_0 (1370)$ among the members in light mass, and $f_0(980), f_0(1500)$ in heavy mass. The complication arises because the isoscalar members of each nonet are subject to an additional flavor mixing known as OZI rule so that $f_0 (500), f_0 (980)$, and similarly $f_0 (1370), f_0 (1500)$, are the mixture of two isoscalar members belonging to an octet and a singlet in SU$_f$(3). The tetraquark mixing framework including the flavor mixing is tested for the isoscalar resonances in terms of the mass splitting and the fall-apart decay modes.

[10]  arXiv:1711.08430 (cross-list from hep-ph) [pdf, other]
Title: Lepton Flavor Violation Induced by a Neutral Scalar at Future Lepton Colliders
Comments: 7 pages, 5 figures, 1 table
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)

Many new physics scenarios beyond the Standard Model often necessitate the existence of a (light) neutral scalar $H$, which might couple to the charged leptons in a flavor violating way, while evading all existing constraints. We show that such scalars could be effectively produced at future lepton colliders, either on-shell or off-shell depending on their mass, and induce lepton flavor violating (LFV) signals, i.e. $e^+ e^- \to \ell_\alpha^\pm \ell_\beta^\mp (+H)$ with $\alpha\neq \beta$. We find that a large parameter space of the scalar mass and the LFV couplings can be probed, well beyond the current low-energy constraints in the lepton sector. In particular, a scalar-loop induced explanation of the longstanding muon $g-2$ anomaly can be directly tested in the on-shell mode.

Replacements for Thu, 23 Nov 17

[11]  arXiv:1212.0332 (replaced) [pdf, ps, other]
Title: Neutron Beta-Decay as Laboratory for Test of Standard Model
Comments: 59 pages, 3 figures and 1 Table. Some misprints are corrected, and the values of X- and Y-integrals in Appendix I are updated
Journal-ref: Phys.Rev. D88, 073002 (2013)
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex); Nuclear Experiment (nucl-ex)
[12]  arXiv:1312.1501 (replaced) [pdf, other]
Title: Update of the ALEPH non-strange spectral functions from hadronic $τ$ decays
Comments: 12 pages, 7 figures. Version 2 fixes a minor problem in the covariance matrices of the spectral functions without affecting the main results and conclusion of the paper. Version 3 corresponds to the published one. Version 4 has the legend of Figs.5(a) and 5(b) improved
Journal-ref: Eur. Phys. J. C (2014) 74:2803
Subjects: High Energy Physics - Experiment (hep-ex); High Energy Physics - Phenomenology (hep-ph)
[13]  arXiv:1704.04708 (replaced) [pdf, ps, other]
Title: CP Asymmetries in Strange Baryon Decays
Comments: final version, slight typos corrected
Journal-ref: Chin. Phys. C42 (2018) no.1, 013101
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)
[14]  arXiv:1705.03897 (replaced) [pdf, other]
Title: Surprises from Complete Vector Portal Theories: New Insights into the Dark Sector and its Interplay with Higgs Physics
Comments: 5 pages, 3 figures; v2: minor corrections, references added, journal version
Journal-ref: Phys.Rev. D96 (2017) no.9, 095006
Subjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Experiment (hep-ex); High Energy Physics - Theory (hep-th)
[15]  arXiv:1705.09500 (replaced) [pdf, other]
Title: Study of Non-Standard Charged-Current Interactions at the MOMENT experiment
Comments: 14 pages, 5 figures. Update references and clarify the formalism of NSIs
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)
[16]  arXiv:1707.01302 (replaced) [pdf, other]
Title: Search for top quark decays $t \rightarrow qH$, with $H\toγγ$, in $\sqrt{s} = 13$ TeV $pp$ collisions using the ATLAS detector
Comments: 41 pages in total, author list starting page 25, 7 figures, 3 tables, submitted to JHEP. All figures are available at this http URL
Journal-ref: Phys. Rev. Lett. 119, 181804 (2017)
Subjects: High Energy Physics - Experiment (hep-ex)
[17]  arXiv:1707.03263 (replaced) [pdf, other]
Title: Measurement of detector-corrected observables sensitive to the anomalous production of events with jets and large missing transverse momentum in $pp$ collisions at $\sqrt{s} = 13$ TeV using the ATLAS detector
Comments: 44 pages in total, author list starting page 28, 6 figures, 2 tables, submitted to EPJC, All figures including auxiliary figures are available at this http URL
Journal-ref: Eur. Phys. J. C 77 (2017) 765
Subjects: High Energy Physics - Experiment (hep-ex)
[18]  arXiv:1709.04294 (replaced) [pdf, other]
Title: Sterile Neutrinos or Flux Uncertainties? - Status of the Reactor Anti-Neutrino Anomaly
Comments: 25 pages, 5 figures. 1 page and table 4 added. Published in JHEP
Journal-ref: JHEP 11 (2017) 099
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)
[19]  arXiv:1711.03288 (replaced) [pdf, other]
Title: Did TOTEM experiment discover the Odderon?
Comments: 6 pages, 2 figures, 3 tables. v.4. Two remaining typos were corrected
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)
[20]  arXiv:1711.04303 (replaced) [pdf, ps, other]
Title: Spin-flavor oscillations of ultrahigh-energy cosmic neutrinos in interstellar space: The role of neutrino magnetic moments
Comments: 18 pages, 4 figures; fixed misprints in Eq. (7)
Journal-ref: PRD 96 (2017) 103017
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Experiment (hep-ex)
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