High Energy Physics - Experiment

New submissions

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New submissions for Tue, 20 Mar 18

[1]
Title: Measurement of the branching fraction of $B \rightarrow D^{(*)}π \ellν$ at Belle using hadronic tagging in fully reconstructed events
Comments: 8 pages, 2 figures, submitted to PRD
Subjects: High Energy Physics - Experiment (hep-ex)

We report a measurement of the branching fraction of the decay $B \rightarrow D^{(*)}\pi \ell\nu$. The analysis uses 772$\times 10^6$ $B\bar{B}$ pairs produced in $e^+e^-\rightarrow \Upsilon(4S)$ data recorded by the Belle experiment at the KEKB asymmetric-energy $e^+e^-$ collider. The tagging $B$ meson in the decay is fully reconstructed in a hadronic decay mode. On the signal side, we reconstruct the decay $B \rightarrow D^{(*)}\pi \ell\nu$ $(\ell=e,\mu)$. The measured branching fractions are $\mathcal{B}(B^+ \rightarrow D^-\pi^+ \ell^+\nu)$ = [4.55 $\pm$ 0.27 (stat.) $\pm$ 0.39 (syst.)]$\times 10^{-3}$, $\mathcal{B}(B^0 \rightarrow \bar{D}^0\pi^- \ell^+\nu)$ = [4.05 $\pm$ 0.36 (stat.) $\pm$ 0.41 (syst.)]$\times 10^{-3}$, $\mathcal{B}(B^+ \rightarrow D^{*-}\pi^+ \ell^+\nu)$ = [6.03 $\pm$ 0.43 (stat.) $\pm$ 0.38 (syst.)]$\times 10^{-3}$, and $\mathcal{B}(B^0 \rightarrow \bar{D}^{*0}\pi^- \ell^+\nu)$ = [6.46 $\pm$ 0.53 (stat.) $\pm$ 0.52 (syst.)]$\times 10^{-3}$. These are in good agreement with the current world average values.

[2]
Title: Search for additional neutral MSSM Higgs bosons in the $ττ$ final state in proton-proton collisions at $\sqrt{s}=$ 13 TeV
Comments: Submitted to JHEP. All figures and tables can be found at this http URL (CMS Public Pages)
Subjects: High Energy Physics - Experiment (hep-ex)

A search is presented for additional neutral Higgs bosons in the $\tau\tau$ final state in proton-proton collisions at the LHC. The search is performed in the context of the minimal supersymmetric extension of the standard model (MSSM), using the data collected with the CMS detector in 2016 at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. To enhance the sensitivity to neutral MSSM Higgs bosons, the search includes production of the Higgs boson in association with b quarks. No significant deviation above the expected background is observed. Model-independent limits at 95% confidence level (CL) are set on the product of the branching fraction for the decay into $\tau$ leptons and the cross section for the production via gluon fusion or in association with b quarks. These limits range from 18 pb at 90 GeV to 3.5 fb at 3.2 TeV for gluon fusion and from 15 pb (at 90 GeV) to 2.5 fb (at 3.2 TeV) for production in association with b quarks. In the m$_{\text{h}}^{\text{mod+}}$ scenario these limits translate into a 95% CL exclusion of $\tan\beta>$ 6 for neutral Higgs boson masses below 250 GeV, where $\tan\beta$ is the ratio of the vacuum expectation values of the neutral components of the two Higgs doublets. The 95% CL exclusion contour reaches 1.6 TeV for $\tan\beta=$ 60.

[3]
Title: Search for $\mathrm{t}\overline{\mathrm{t}}$H production in the all-jet final state in proton-proton collisions at $\sqrt{s}=$ 13 TeV
Comments: Submitted to JHEP. All figures and tables can be found at this http URL (CMS Public Pages)
Subjects: High Energy Physics - Experiment (hep-ex)

A search is presented for the associated production of a Higgs boson with a top quark pair in the all-jet final state. Events containing seven or more jets are selected from a sample of proton-proton collisions at $\sqrt{s} =$ 13 TeV collected with the CMS detector at the LHC in 2016, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. To separate the $\mathrm{t}\overline{\mathrm{t}}$H signal from the irreducible $\mathrm{t}\overline{\mathrm{t}}+\mathrm{b}\overline{\mathrm{b}}$ background, the analysis assigns leading order matrix element signal and background probability densities to each event. A likelihood-ratio statistic based on these probability densities is used to extract the signal. The results are provided in terms of an observed $\mathrm{t}\overline{\mathrm{t}}$H signal strength relative to the standard model production cross section $\mu=\sigma/\sigma_\mathrm{SM}$, assuming a Higgs boson mass of 125 GeV. The best fit value is $\hat{\mu} =$ 0.9 $\pm$ 0.7 (stat) $\pm$ 1.3 (syst) = 0.9 $\pm$ 1.5 (tot), and the observed and expected upper limits are, respectively, $\mu <$ 3.8 and $<$ 3.1 at 95% confidence levels.

[4]
Title: Jet Substructure at the Large Hadron Collider : Experimental Review
Comments: 62 pages, 58 figures. L. Asquith, C. Delitzsch, A. Schmidt, editors
Subjects: High Energy Physics - Experiment (hep-ex)

Jet substructure has emerged to play a central role at the Large Hadron Collider (LHC), where it has provided numerous innovative new ways to search for new physics and to probe the Standard Model, particularly in extreme regions of phase space. In this article we focus on a review of the development and use of state-of-the-art jet substructure techniques by the ATLAS and CMS experiments. Much of the work in this field in recent years has been galvanized by the Boost Workshop Series, which continues to inspire fruitful collaborations between experimentalists and theorists. We hope that this review will prove a useful introduction and reference to experimental aspects of jet substructure at the LHC. A companion overview of recent progress in theory and machine learning approaches is given in 1709.04464, the complete review will be submitted to Reviews of Modern Physics.

Cross-lists for Tue, 20 Mar 18

[5]  arXiv:1803.06379 (cross-list from physics.ins-det) [pdf, other]
Title: Photon detector system performance in the DUNE 35-ton prototype liquid argon time projection chamber
Subjects: Instrumentation and Detectors (physics.ins-det); High Energy Physics - Experiment (hep-ex)

The 35-ton prototype for the Deep Underground Neutrino Experiment far detector was a single-phase liquid argon time projection chamber with an integrated photon detector system, all situated inside a membrane cryostat. The detector took cosmic-ray data for six weeks during the period of February 1, 2016 to March 12, 2016. The performance of the photon detection system was checked with these data. An installed photon detector was demonstrated to measure the arrival times of cosmic-ray muons with a resolution better than 32 ns, limited by the timing of the trigger system. A measurement of the timing resolution using closely-spaced calibration pulses yielded a resolution of 15 ns for pulses at a level of 6 photo-electrons. Scintillation light from cosmic-ray muons was observed to be attenuated with increasing distance with a characteristic length of $155 \pm 28$ cm.

[6]  arXiv:1803.06478 (cross-list from hep-ph) [pdf, other]
Title: Exploring physics beyond the Standard Electroweak Model in the light of supersymmetry
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)

In this thesis we try to discuss certain phenomenological aspects of an R-parity violating non-minimal supersymmetric model, called $\mu\nu$SSM. We show that $\mu\nu$SSM can provide a solution to the $\mu$-problem of supersymmetry and can simultaneously accommodate the existing three flavour global data from neutrino experiments even at the tree level with the simple choice of flavour diagonal neutrino Yukawa couplings. We show that it is also possible to achieve different mass hierarchies for light neutrinos at the tree level itself. In $\mu\nu$SSM, the effect of R-parity violation together with a seesaw mechanism with TeV scale right-handed neutrinos are instrumental for light neutrino mass generation. We also analyze the stability of tree level neutrino masses and mixing with the inclusion of one-loop radiative corrections. In addition, we investigate the sensitivity of the one-loop corrections to different light neutrino mass orderings. Decays of the lightest supersymmetric particle were also computed and ratio of certain decay branching ratios was observed to correlate with certain neutrino mixing angle. We extend our analysis for different natures of the lightest supersymmetric particle as well as with various light neutrino mass hierarchies. We present estimation for the length of associated displaced vertices for various natures of the lightest supersymmetric particle which can act as a discriminating feature at a collider experiment. We also present an unconventional signal of Higgs boson in supersymmetry which can lead to a discovery, even at the initial stage of the large hadron collider running. Besides, we show that a signal of this kind can also act as a probe to the seesaw scale. Certain other phenomenological issues have also been addressed.

[7]  arXiv:1803.06560 (cross-list from hep-ph) [pdf, ps, other]
Title: Leading Pomeron Contributions and the TOTEM Data at 13 TeV
Comments: 4 pages, 1 table, 1 figure, Poster presented at the XIV International Workshop on Hadron Physics, Florian\'opolis, Brazil, March 2018
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)

The recent data by the TOTEM Collaboration on $\sigma_{tot}$ and $\rho$ at 13 TeV, have shown agreement with a leading Odderon contribution at the highest energies, as demonstrated in the very recent analysis by Martynov and Nicolescu (MN). In order to investigate the same dataset by means of Pomeron dominance, we introduce a general class of forward scattering amplitude, with leading contributions even under crossing, associated with simple, double and triple poles in the complex angular momentum plane. For the lower energy region, we consider the usual non-degenerated Regge trajectories, with even and odd symmetry. The analytic connection between $\sigma_{tot}$ and $\rho$ is obtained by means of dispersion relations and we carry out fits to $pp$ and $\bar{p}p$ data in the interval $\sqrt{s}=5$ GeV - 13 TeV; following MN we consider only the TOTEM data at the LHC energy region. From the fits, we conclude that the general analytic model, as well as some particular cases representing standard parameterizations, are not able to describe satisfactorily the $\sigma_{tot}$ and $\rho$ data at 13 TeV. Further analyses in course and some perspectives are outlined.

[8]  arXiv:1803.06667 (cross-list from hep-ph) [pdf, other]
Title: Subleading-power corrections to the radiative leptonic $B \to γ \ell ν$ decay in QCD
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex); High Energy Physics - Lattice (hep-lat)

Applying the method of light-cone sum rules with photon distribution amplitudes, we compute the subleading-power correction to the radiative leptonic $B \to \gamma \ell \nu$ decay, at next-to-leading order in QCD for the twist-two contribution and at leading order in $\alpha_s$ for the higher-twist contributions, induced by the hadronic component of the collinear photon. The leading-twist hadronic photon effect turns out to preserve the symmetry relation between the two $B \to \gamma$ form factors due to the helicity conservation, however, the higher-twist hadronic photon corrections can yield symmetry-breaking effect already at tree level in QCD. Using the conformal expansion of photon distribution amplitudes with the non-perturbative parameters estimated from QCD sum rules, the twist-two hadronic photon contribution can give rise to approximately 30\% correction to the leading-power "direct photon" effect computed from the perturbative QCD factorization approach. In contrast, the subleading-power corrections from the higher-twist two-particle and three-particle photon distribution amplitudes are estimated to be of ${\cal O} (3 \sim 5\%)$ with the light-cone sum rule approach. We further predict the partial branching fractions of $B \to \gamma \ell \nu$ with a photon-energy cut $E_{\gamma} \geq E_{\rm cut}$, which are of interest for determining the inverse moment of the leading-twist $B$-meson distribution amplitude thanks to the forthcoming high-luminosity Belle II experiment at KEK.

[9]  arXiv:1803.06793 (cross-list from hep-ph) [pdf, ps, other]
Title: $Z^\prime$ portal dark matter in the minimal $B-L$ model
Comments: 10 pages, 5 figures, Review article to be published in Advances in High Energy Physics
Subjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Experiment (hep-ex)

In this article, we consider a dark matter scenario in the context of the minimal extension of the Standard Model (SM) with a $B-L$ (baryon number minus lepton number) gauge symmetry, where three right-handed neutrinos with a $B-L$ charge $-1$ and a $B-L$ Higgs field with a $B-L$ charge $+2$ are introduced to make the model anomaly-free and to break the $B-L$ gauge symmetry, respectively. The $B-L$ gauge symmetry breaking generates the Majorana masses for the right-handed neutrinos. We introduce a Z$_2$ symmetry to the model and assign an odd parity only for one right-handed neutrino, and hence the Z$_2$-odd right-handed neutrino is stable and the unique dark matter candidate in the model. The so-called minimal seesaw works with the other two right-handed neutrinos and reproduces the current neutrino oscillation data. We consider the case that the dark matter particle communicates with the SM particles through the $B-L$ gauge boson ($Z^{\prime}_{B-L}$ boson), and obtain a lower bound on the $B-L$ gauge coupling ($\alpha_{B-L}$) as a function of the $Z^{\prime}_{B-L}$ boson mass ($m_{Z^{\prime}}$) from the observed dark matter relic density. On the other hand, we interpret the recent LHC Run-2 results on the search for a $Z^{\prime}$ boson resonance to an upper bound on $\alpha_{B-L}$ as a function of $m_{Z^{\prime}}$. These two constraints are complementary to narrow down an allowed parameter region for this "$Z^{\prime}$ portal" dark matter scenario, leading to a lower mass bound of $m_{Z^{\prime}} \geq 3.9$ TeV.

[10]  arXiv:1803.06831 (cross-list from hep-ph) [pdf, ps, other]
Title: Electromagnetic multipole moments of the $P_c^+(4380)$ pentaquark in light-cone QCD
Authors: U. Ozdem, K. Azizi
Comments: 13 pages, 1 figure and 1 table
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex); High Energy Physics - Lattice (hep-lat)

We calculate the electromagnetic multipole moments of the $P_c^+(4380)$ pentaquark by modeling it as the diquark-diquark-antiquark and $\bar D^*\Sigma_c$ molecular state with quantum numbers $J^P = \frac{3}{2}^-$. In particular, the magnetic dipole, electric quadrupole and magnetic octupole moments of this particle are extracted in the framework of light-cone QCD sum rule. The values of the electromagnetic multipole moments obtained via two pictures differ substantially from each other, which can be used to pin down the underlying structure of $P_c^+(4380)$. The comparison of any future experimental data on the electromagnetic multipole moments of the $P_c^+(4380)$ pentaquark with the results of the present work can shed light on the nature and inner quark organization of this state.

[11]  arXiv:1803.06860 (cross-list from physics.ins-det) [pdf, other]
Title: Combined readout of a triple-GEM detector
Subjects: Instrumentation and Detectors (physics.ins-det); High Energy Physics - Experiment (hep-ex)

Optical readout of GEM based devices by means of high granularity and low noise CMOS sensors allows to obtain very interesting tracking performance. Space resolution of the order of tens of $\mu$m were measured on the GEM plane along with an energy resolution of 20%$\div$30%. The main limitation of CMOS sensors is represented by their poor information about time structure of the event. In this paper, the use of a concurrent light readout by means of a suitable photomultiplier and the acquisition of the electric signal induced on the GEM electrode are exploited to provide the necessary timing informations. The analysis of the PMT waveform allows a 3D reconstruction of each single clusters with a resolution on z of 100 $\mu$m. Moreover, from the PMT signals it is possible to obtain a fast reconstruction of the energy released within the detector with a resolution of the order of 25% even in the tens of keV range useful, for example, for triggering purpose.

Replacements for Tue, 20 Mar 18

[12]  arXiv:1703.05371 (replaced) [pdf, other]
Title: Directional Sensitivity In Light-Mass Dark Matter Searches With Single-Electron Resolution Ionization Detectors
Subjects: Instrumentation and Detectors (physics.ins-det); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Materials Science (cond-mat.mtrl-sci); High Energy Physics - Experiment (hep-ex); Computational Physics (physics.comp-ph)
[13]  arXiv:1711.01265 (replaced) [pdf, other]
Title: Science with e-ASTROGAM (A space mission for MeV-GeV gamma-ray astrophysics)
Comments: White Book, submitted to Journal of High Energy Astrophysics (Elsevier)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR); High Energy Physics - Experiment (hep-ex)
[14]  arXiv:1801.06067 (replaced) [pdf, other]
Title: The radiative corrections to double-Dalitz decays revisited
Comments: 22 pages, 9 figures; minor changes added (results unchanged). Matches the published version in PRD
Journal-ref: Phys.Rev. D97, 056010 (2018)
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex); Nuclear Theory (nucl-th)
[15]  arXiv:1802.02948 (replaced) [pdf, other]
Title: Fragmentation-fraction ratio $f_{Ξ_b}/f_{Λ_b}$ in $b$- and $c$-baryon decays
Comments: 13 pages, 1 table, 1 figure. Version published in EPJC
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex)
[16]  arXiv:1802.03421 (replaced) [pdf, ps, other]
Title: Measurement of the Decays $Λ_c\to Σππ$ at Belle
Subjects: High Energy Physics - Experiment (hep-ex)
[17]  arXiv:1802.05416 (replaced) [pdf, ps, other]
Title: Magnetic moments of the lowest-lying singly heavy baryons
Comments: 9 pages. Table III and IV in the previous version were removed. The manuscript has been revised for publication
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Experiment (hep-ex); Nuclear Theory (nucl-th)
[18]  arXiv:1803.01224 (replaced) [pdf, other]
Title: Coherent Elastic Neutrino Nucleus Scattering (CE$ν$NS) as a probe of $Z'$ through kinetic and mass mixing effects