We present a new approach to jet definition alternative to clustering methods, such as the anti-kT scheme, that exploit kinematic data directly. Instead the new method uses kinematic information to represent the particles in a multidimensional space, as in spectral clustering. After confirming its Infra-Red (IR) safety, we compare its performance in analysing gg → H 125 GeV → H 40 GeV H 40 GeV →   <math> <mi>b</mi> <mover> <mi>b</mi> <mo>¯</mo> </mover> <mi>b</mi> <mover> <mi>b</mi> <mo>¯</mo> </mover> </math>  $$ b\overline{b}b\overline{b} $$ , gg → H 500 GeV → H 125 GeV H 125 GeV →   <math> <mi>b</mi> <mover> <mi>b</mi> <mo>¯</mo> </mover> <mi>b</mi> <mover> <mi>b</mi> <mo>¯</mo> </mover> </math>  $$ b\overline{b}b\overline{b} $$  and gg,   <math> <mi>q</mi> <mover> <mi>q</mi> <mo>¯</mo> </mover> </math>  $$ q\overline{q} $$  →   <math> <mi>t</mi> <mover> <mi>t</mi> <mo>¯</mo> </mover> </math>  $$ t\overline{t} $$  →   <math> <mi>b</mi> <mover> <mi>b</mi> <mo>¯</mo> </mover> <msup> <mi>W</mi> <mo>+</mo> </msup> <msup> <mi>W</mi> <mo>−</mo> </msup> </math>  $$ b\overline{b}{W}^{+}{W}^{-} $$  →   <math> <mi>b</mi> <mover> <mi>b</mi> <mo>¯</mo> </mover> <mi>jj</mi> <mi>ℓ</mi> <msub> <mi>v</mi> <mi>ℓ</mi> </msub> </math>  $$ b\overline{b} jj\mathrm{\ell}{v}_{\mathrm{\ell}} $$  events from Monte Carlo (MC) samples, specifically, in reconstructing the relevant final states, to that of the anti-k  T  algorithm. Finally, we show that the results for spectral clustering are obtained without any change in the parameter settings of the algorithm, unlike the anti-k  T  case, which requires the cone size to be adjusted to the physics process under study.

United Kingdom

Giorgio Cerro

Srinandan Dasmahapatra

Czechia

Henry Day-Hall

Billy Ford

Stefano Moretti

Claire Shepherd-Themistocleous

Spectral clustering for jet physics

We study displaced signatures of sneutrino pairs potentially emerging at the Large Hadron Collider (LHC) in a Next-to-Minimal Supersymmetric Standard Model supplemented with right-handed neutrinos triggering a Type-I seesaw mechanism. We show how such signatures can be established through a heavy Higgs portal, the sneutrinos then decaying to charged leptons and charginos giving rise to further leptons or hadrons. We finally illustrate how the Yukawa parameters of neutrinos can be extracted by measuring the lifetime of the sneutrino from the displaced vertices, thereby characterising the dynamics of the underlying mechanism of neutrino mass generation. We show our numerical results for the case of both the current and High-Luminosity LHC.

India

Amit Chakraborty

Harri Waltari

Extraction of neutrino Yukawa parameters from displaced vertices of sneutrinos

We investigate the potential of the Large Hadron Collider (LHC) to probe one of the most compelling beyond the Standard Model frameworks—walking technicolor (WTC), involving strong dynamics and having a slowly running (walking) new strong coupling. For this purpose we use recent LHC Run 2 data to explore the full parameter space of the minimal WTC model using dilepton signatures from heavy neutral <math><msup><mi>Z</mi><mo>′</mo></msup></math> and <math><msup><mi>Z</mi><mrow><mo>′′</mo></mrow></msup></math> resonances predicted by the model. This signature is the most promising one for discovery of WTC at the LHC for the low-intermediate values of the <math><mover><mi>g</mi><mo>˜</mo></mover></math> coupling—one of the principle parameters of WTC. We have demonstrated complementarity of the dilepton signals from both resonances, established the most up-to-date limit on the WTC parameter space, and provided projections for the LHC potential to probe the WTC parameter space at higher future luminosities and upgraded energy. We have explored the whole four-dimensional parameter space of the model and have found the most conservative limit on the WTC scale <math><msub><mi>M</mi><mi>A</mi></msub></math> above 3 TeV for the low values of <math><mover><mi>g</mi><mo>˜</mo></mover></math>, which is significantly higher than previous limits established by the LHC collaborations.

Alexander Belyaev

Azaria Coupe

Denmark

Mads Frandsen

Emmanuel Olaiya

Walking technicolor in light of <math><msup><mi>Z</mi><mo>′</mo></msup></math> searches at the LHC

In this paper, we discuss the potential of observing heavy neutrino ( ν h ) signatures of a U(1) B − L enlarged Standard Model (SM) encompassing three heavy Majorana neutrinos alongside the known light neutrino states at the Large Hadron Collider (LHC). We exploit the theoretical decay via a heavy (non-SM-like) Higgs boson and Z ′ production followed by ν h → l ± W ∓(∗) and ν h → ν l Z (∗) decays, ultimately yielding a 3 l  + 2 j  +  E T miss signature and, depending upon how boosted the final state objects are, we define different possible selections aimed at improving the signal to background ratio in LHC Run 2 data for a wide range of heavy neutrino masses.

Elena Accomando

Luigi Rose

Extra Higgs boson and Z ′ as portals to signatures of heavy neutrinos at the LHC

A dedicated search is presented for new phenomena in inclusive 8- and 10-jet final states with low missing transverse momentum, with and without identification of jets originating from b quarks. The analysis is based on data from proton–proton collisions corresponding to an integrated luminosity of 19.7fb−1 collected with the CMS detector at the LHC at s=8TeV . The dominant multijet background expectations are obtained from low jet multiplicity control samples. Data agree well with the standard model background predictions, and limits are set in several benchmark models. Colorons (axigluons) with masses between 0.6 and 0.75 (up to 1.15) TeV are excluded at 95% confidence level. Similar exclusion limits for gluinos in R -parity violating supersymmetric scenarios are from 0.6 up to 1.1 TeV. These results comprise the first experimental probe of the coloron and axigluon models in multijet final states.

Armenia

Vardan Khachatryan

Albert M Sirunyan

Armen Tumasyan

Austria

Wolfgang Adam

Ece Aşılar

Thomas Bergauer

Johannes Brandstetter

Erica Brondolin

Marko Dragicevic

Janos Erö

Martin Flechl

Markus Friedl

Rudolf Fruehwirth

Vasile Mihai Ghete

Christian Hartl

Natascha Hörmann

Josef Hrubec

Manfred Jeitler

Axel König

Ilse Krätschmer

Dietrich Liko

Takashi Matsushita

Ivan Mikulec

Dinyar Rabady

Navid Rad

Babak Rahbaran

Herbert Rohringer

Jochen Schieck

Josef Strauss

Wolfgang Treberer-Treberspurg

Wolfgang Waltenberger

Claudia-Elisabeth Wulz

Belarus

Vladimir Mossolov

Nikolai Shumeiko

Juan Suarez Gonzalez

Belgium

Sara Alderweireldt

Eddi A De Wolf

Xavier Janssen

Jasper Lauwers

Merijn Van De Klundert

Hans Van Haevermaet

Pierre Van Mechelen

Nick Van Remortel

Alex Van Spilbeeck

Shimaa Abu Zeid

Freya Blekman

Jorgen D'Hondt

Nadir Daci

Isabelle De Bruyn

Kevin Deroover

Natalie Heracleous

Steven Lowette

Seth Moortgat

Lieselotte Moreels

Annik Olbrechts

Quentin Python

Stefaan Tavernier

Walter Van Doninck

Petra Van Mulders

Isis Van Parijs

Hugues Brun

Cécile Caillol

Barbara Clerbaux

Gilles De Lentdecker

Hugo Delannoy

Giuseppe Fasanella

Laurent Favart

Reza Goldouzian

Anastasia Grebenyuk

Georgia Karapostoli

Thomas Lenzi

Alexandre Léonard

Jelena Luetic

Thierry Maerschalk

Andrey Marinov

Aidan Randle-conde

Tomislav Seva

Catherine Vander Velde

Pascal Vanlaer

Ryo Yonamine

Florian Zenoni

China

Fengwangdong Zhang

Anna Cimmino

Tom Cornelis

Didar Dobur

Alexis Fagot

Guillaume Garcia

Muhammad Gul

Deniz Poyraz

Sinem Salva Diblen

Robert Schöfbeck

Michael Tytgat

Ward Van Driessche

Efe Yazgan

Nicolas Zaganidis

Hamed Bakhshiansohi

France

Camille Beluffi

Olivier Bondu

Sébastien Brochet

Giacomo Bruno

Search for new phenomena in events with high jet multiplicity and low missing transverse momentum in proton–proton collisions at s=8TeV

We examine the observability of heavy neutrino ( ν h ) signatures of a U(1)′ enlarged Standard Model (SM) encompassing three heavy Majorana neutrinos alongside the known light neutrino states at the the Large Hadron Collider (LHC). We show that heavy neutrinos can be rather long-lived particles producing distinctive displaced vertices that can be accessed in the CERN LHC detectors. We concentrate here on the gluon fusion production mechanism gg → H 1,2 → ν h ν h , where H 1 is the discovered SM-like Higgs and H 2 is a heavier state, yielding displaced leptons following ν h decays into weak gauge bosons. Using data collected by the end of the LHC Run 2, these signatures would prove to be accessible with negligibly small background.

Novel SM-like Higgs decay into displaced heavy neutrino pairs in U(1)′ models

The last few years have been witness to a proliferation of new results concerning heavy exotic hadrons. Experimentally, many new signals have been discovered that could be pointing towards the existence of tetraquarks, pentaquarks, and other exotic configurations of quarks and gluons. Theoretically, advances in lattice field theory techniques place us at the cusp of understanding complex coupled-channel phenomena, modelling grows more sophisticated, and effective field theories are being applied to an ever greater range of situations. It is thus an opportune time to evaluate the status of the field. In the following, a series of high priority experimental and theoretical issues concerning heavy exotic hadrons is presented.

United States

R.A. Briceño

T.D. Cohen

S. Coito

J.J. Dudek

E. Eichten

Germany

C.S. Fischer

M. Fritsch

W. Gradl

A. Jackura

M. Kornicer

Brazil

G. Krein

R. F. Lebed

F. A. Machado

R. E. Mitchell

C.J. Morningstar

Ireland

M. Peardon

M. R. Pennington

K. Peters

J. M. Richard

C. P. Shen

M.R. Shepherd

T. Skwarnicki

E. S. Swanson

A. P. Szczepaniak

C. Z. Yuan

Issues and Opportunities in Exotic HadronsSupported by U.S. Department of Energy (Cohen); the Institute of Modern Physics and Chinese Academy of Sciences under contract Y104160YQ0 and agreement No. 2015-BH-02 (Coito); the U.S. Department of Energy, for grant DE-AC05-06OR23177, under which Jefferson Science Associates, LLC, manages and operates Jefferson Laboratory and DE-SC0006765, Early Career award (Dudek); Fermilab, operated by the Fermi Research Alliance under contract number DEAC02-07CH11359 with the U.S. Department of Energy (Eichten); BMBF, under contract No. 06GI7121, and the DAAD under contract No. 56889822 and by the Helmholtz International Center for FAIR within the LOEWE program of the State of Hesse (Fischer); the German Research Foundation DFG under contract number Collaborative Research Centre CRC-1044 (Gradl); the Conselho Nacional de Desenvolvimento CientÃ­fico e TecnolÃ³gico - CNPq, Grant No. 305894/2009-9 and FundaÃ§Ã£o de Amparo Ã Pesquisa do Estado de SÃ£o Paulo - FAPESP, Grant No. 2013/01907-0 (Krein); U.S. National Science Foundation, under grants PHY-1068286 and PHY-1403891 (Lebed); the Brazilian National Council for Scientific and Technological Development under grant CNPq/CAPES-208188/2014-2 (Machado); U.S. Department of Energy under grant DE-FG02-05ER41374 (Mitchell); U.S. National Science Foundation under grant PHY-1306805 (Morningstar); U.S. Department of Energy, supported by Jefferson Science Associates, LLC under contract No. DE-AC05-06OR23177 (Pennington); the National Natural Science Foundation of China (NSFC) under contract No. 11575017, the Ministry of Science and Technology of China under Contract No. 2015CB856701 (Shen); U.S. Department of Energy, under grant DE-FG02-05ER41374 (Shepherd); U.S. National Science Foundation under grant PHY-1507572 (Skwarnicki); U.S. Department of Energy, under contract DE-AC05-06OR23177 and grant DE-FG0287ER40365 (Szczepaniak); the National Natural Science Foundation of China (NSFC) under contract numbers 11235011 and 11475187 (Yuan).

The Forward-Backward Asymmetry (AFB) in Z ′ physics is commonly only perceived as the observable which possibly allows one to interpret a Z ′ signal appearing in the Drell-Yan channel by distinguishing different models of such (heavy) spin-1 bosons. In this paper, we revisit this issue, showing that the absence of any di-lepton rapidity cut, which is commonly used in the literature, can enhance the potential of the observable at the LHC. We moreover examine the ability of AFB in setting bounds on or even discovering a Z ′ at the Large Hadron Collider (LHC) concluding that it may be a powerful tool for this purpose. We analyse two different scenarios: Z ′-bosons with a narrow and wide width, respectively. We find that, in the first case, the significance of the AFB search can be comparable with that of the ‘bump’ search usually adopted by the experimental collaborations; however, in being a ratio of (differential) cross sections, the AFB has the advantage of reducing experimental systematics as well as theoretical errors due to PDF uncertainties. In the second case, the AFB search can outperform the bump search in terms of differential shape, meaning the AFB distribution may be better suited for new broad resonances than the event counting strategy usually adopted in such cases.

Juri Fiaschi

Ken Mimasu

Forward-backward asymmetry as a discovery tool for Z′ bosons at the LHC