Wed·Jan 24, 2018Wednesday·January 24, 2018

1. 01*

   Phenomenology of single-inclusive jet production with jet radius and threshold resummation

   Xiaohui Liu🇨🇳 · Sven-Olaf Moch🇩🇪 · Felix Ringer🇺🇸

   We perform a detailed study of inclusive jet production cross sections at the LHC and compare the QCD theory predictions based on the recently developed formalism for threshold and jet radius joint resummation at next-to-leading logarithmic accuracy to inclusive jet data collected by the CMS collaboration at $\sqrt{S}=7$ and $13$TeV. We compute the cross sections at next-to-leading order in QCD with and without the joint resummation for different choices of jet radii $R$ and observe that the joint resummation leads to crucial improvements in the description of the data. Comprehensive studies with different parton distribution functions demonstrate the necessity of considering the joint resummation in fits of those functions based on the LHC jet data.

   hep-phhep-exnucl-exPRD(2018)·47 citations
2. 02*

   Precision calculations for $h\to WW/ZZ\to 4$ fermions in a Singlet Extension of the Standard Model with Prophecy4f

   Lukas Altenkamp🇩🇪 · Michele Boggia🇩🇪 · Stefan Dittmaier🇩🇪

   We consider an extension of the Standard Model by a real singlet scalar field with a $Z_2$-symmetric Lagrangian and spontaneous symmetry breaking with vacuum expectation value for the singlet. Considering the lighter of the two scalars of the theory to be the 125GeV Higgs particle, we parametrize the scalar sector by the mass of the heavy Higgs boson, a mixing angle $\alpha$, and a scalar Higgs self-coupling ${\lambda }_{12}$. Taking into account theoretical constraints from perturbativity and vacuum stability, we compute next-to-leading-order electroweak and QCD corrections to the decays $h\to WW/ZZ\to 4$ fermions of the light Higgs boson for some scenarios proposed in the literature. We formulate two renormalization schemes and investigate the conversion of the input parameters between the schemes, finding sizeable effects. Solving the renormalization-group equations for the MSbar parameters $\alpha$ and ${\lambda }_{12}$, we observe a significantly reduced scale and scheme dependence in the next-to-leading-order results. For some scenarios suggested in the literature, the total decay width for the process $h\to 4f$ is computed as a function of the mixing angle and compared to the width of a corresponding Standard Model Higgs boson, revealing deviations below 10%. Differential distributions do not show significant distortions by effects beyond the Standard Model. The calculations are implemented in the Monte Carlo generator Prophecy4f, which is ready for applications in data analyses in the framework of the singlet extension.

   hep-phJHEP(2018)·40 citations
3. 03*

   The effect of interference on the trident process in a constant crossed field

   B. King🇬🇧 · A. M. Fedotov🇷🇺

   We perform a complete calculation of electron-seeded pair-creation (the trident process) in a constant crossed electromagnetic background. Unlike earlier treatments, we include the interference between exchange diagrams. We find this exchange interference can be written as a contribution solely to the one-step process, and for small quantum nonlinearity parameter is of the same order as other one-step terms. We find the exchange interference further suppresses the one-step process in this parameter regime. Our findings further support the crucial assumption made in laser-plasma simulation codes that at high intensities, the trident process can be well-approximated by repeated iteration of the single-vertex subprocesses. The applicability of this assumption to higher-vertex processes has fundamental importance to the development of simulation capabilities.

   hep-phphysics.plasm-phPRD(2018)·45 citations
4. 04*

   Cosmologically allowed regions for the axion decay constant $F_a$

   Masahiro Kawasaki🇯🇵 · Eisuke Sonomoto🇯🇵 · Tsutomu T. Yanagida🇯🇵

   If the Peccei-Quinn symmetry is already broken during inflation, the decay constant $F_a$ of the axion can be in a wide region from $10^{11}$ GeV to $10^{18}$ GeV for the axion being the dominant dark matter. In this case, however, the axion causes the serious cosmological problem, isocurvature perturbation problem, which severely constrains the Hubble parameter during inflation. The constraint is relaxed when Peccei-Quinn scalar field takes a large value $\sim M_p$ (Planck scale) during inflation. In this letter, we point out that the allowed region of the decay constant $F_a$ is reduced to a rather narrow region for a given tensor-to-scalar ratio $r$ when Peccei-Quinn scalar field takes $\sim M_p$ during inflation. For example, if the ratio $r$ is determined as $r\gtrsim 10^{-3}$ in future measurements, we can predict $F_a\simeq (0.1-1.4)\times 10^{12}$ GeV for domain wall number $N_{\text{DW}}=6$.

   hep-phastro-ph.COPLB(2018)·26 citations
5. 05*

   Baryon-antibaryon dynamics in relativistic heavy-ion collisions

   Eduard Seifert🇩🇪 · Wolfgang Cassing🇩🇪

   The dynamics of baryon-antibaryon annihilation and reproduction ($B\bar{B}\leftrightarrow 3M$) is studied within the Parton-Hadron-String Dynamics (PHSD) transport approach for Pb+Pb and Au+Au collisions as a function of centrality from lower Super Proton Synchrotron (SPS) up to Large Hadron Collider (LHC) energies on the basis of the quark rearrangement model (QRM). At Relativistic Heavy-Ion Collider (RHIC) energies we find a small net reduction of baryon-antibaryon ($B\bar{B}$) pairs while for the LHC energy of $\sqrt{s_{NN}}$ = 2.76 GeV a small net enhancement is found relative to calculations without annihilation (and reproduction) channels. Accordingly, the sizeable difference between data and statistical calculations in Pb+Pb collisions at $\sqrt{s_{NN}}$= 2.76 TeV for proton and antiproton yields \cite{53}, where a deviation of 2.7 $\sigma$ was claimed by the ALICE Collaboration, should not be attributed to a net antiproton annihilation. This is in line with the observation that no substantial deviation between the data and statistical hadronization model (SHM) calculations is seen for antihyperons, since according to the PHSD analysis the antihyperons should be modified by the same amount as antiprotons. As the PHSD results for particle ratios are in line with the ALICE data (within error bars) this might point towards a deviation from statistical equilibrium in the hadronization (at least for protons/antiprotons). Furthermore, we find that the $B\bar{B}\leftrightarrow 3M$ reactions are more effective at lower SPS energies where a net suppression for antiprotons and antihyperons up to a factor of 2 -- 2.5 can be extracted from the PHSD calculations for central Au+Au collisions.

   hep-phnucl-thPRC(2018)·18 citations
6. 06*

   On the LHC sensitivity for non-thermalised hidden sectors

   Felix Kahlhoefer🇩🇪

   We show under rather general assumptions that hidden sectors that never reach thermal equilibrium in the early Universe are also inaccessible for the LHC. In other words, any particle that can be produced at the LHC must either have been in thermal equilibrium with the Standard Model at some point or must be produced via the decays of another hidden sector particle that has been in thermal equilibrium. To reach this conclusion, we parametrise the cross section connecting the Standard Model to the hidden sector in a very general way and use methods from linear programming to calculate the largest possible number of LHC events compatible with the requirement of non-thermalisation. We find that even the HL-LHC cannot possibly produce more than a few events with energy above 10 GeV involving states from a non-thermalised hidden sector.

   hep-phPLB(2018)·17 citations
7. 07*

   Spin-1 particles and perturbative QCD

   J. P. B. C. de Melo (LFTC - Cruzeiro do Sul)🇧🇷 · T. Frederico (Instituto Tecnológico de Aeronáutica - ITA)🇧🇷 · Chueng -R. Ji (Departament of Physics, North Carolina State University, NCSU)🇺🇸

   Due to the angular condition in the light-front dynamics (LFD), the extraction of the electromagnetic form factors for spin-1 particles can be uniquely determined taking into account implicitly non-valence and/or the zero-mode contributions to the matrix elements of the electromagnetic current. No matter which matrix elements of the electromagnetic current is used to extract the electromagnetic form factors, the same unique result is obtained. As physical observables, the electromagnetic form factors obtained from matrix elements of the current in LFD must be equal to those obtained in the instant form calculations. Recently, the Babar collaboration \cite{Aubert2008} has analyzed the reaction $e^{+}{e}^{-}\to {\rho }^{+}+{\rho }^{-}$ at $\sqrt{s}=10.58GeV$ to measure the cross section as well as the ratios of the helicity amplitudes $F_{{\lambda }^{\prime }\lambda }$. We present our recent analysis of the Babar data for the rho meson considering the angular condition in LFD to put a stringent test on the onset of asymptotic perturbative QCD and predict the energy regime where the subleading contributions are still considerable.

   hep-phhep-exhep-thnucl-ex+1Few Body Syst.(2018)·1 citation
8. 08*

   Leptoquark toolbox for precision collider studies

   Ilja Doršner🇭🇷 · Admir Greljo🇩🇪

   We implement scalar and vector leptoquark (LQ) models in the universal FeynRules output (UFO) format assuming the Standard Model fermion content and conservation of baryon and lepton numbers. Scalar LQ implementations include next-to-leading order (NLO) QCD corrections. We report the NLO QCD inclusive cross sections in proton-proton collisions at 13 TeV, 14 TeV, and 27 TeV for all on-shell LQ production processes. These comprise (i) LQ pair production ($pp\to \Phi \Phi$) and (ii) single LQ + lepton production ($pp\to \Phi \ell$) for all initial quark flavours ($u$, $d$, $s$, $c$, and $b$). Vector LQ implementation includes adjustable non-minimal QCD coupling. We discuss several aspects of LQ searches at a hadron collider, emphasising the implications of $SU(2)$ gauge invariance, electroweak and flavour constraints, on the possible signatures. Finally, we outline the high-$p_T$ search strategy for LQs recently proposed in the literature to resolve experimental anomalies in $B$-meson decays. In this context, we stress the importance of complementarity of the three LQ related processes, namely, $pp\to \Phi \Phi$, $pp\to \Phi \ell$, and $pp\to \ell \ell$.

   hep-phhep-exJHEP(2018)·155 citations
9. 09*

   Pion nucleus Drell-Yan process and parton transverse momentum in the pion

   Federico Alberto Ceccopieri🇧🇪 · Aurore Courtoy🇲🇽 · Santiago Noguera🇪🇸 · Sergio Scopetta🇮🇹

   We present a thorough analysis of unpolarized Drell-Yan (DY) pair production in pion-nucleus scattering. On the nucleus side, we use nuclear parton distributions along with parametrisations of the nucleon partonic transverse distribution available in the literature. Partonic longitudinal and transverse distributions of the pion are those obtained in a recent calculation in a Nambu-Jona Lasinio (NJL) framework, with Pauli-Villars regularization. The scale of the NJL model is fixed by a comparison between NLO predictions based on NJL evolved pion distributions and rapidity differential DY cross sections data. The resulting distributions are then used to describe, up to next-to-leading logarithmic accuracy, the transverse momentum spectrum of dilepton pairs up to a transverse momentum of 2 GeV. With no additional parameters, fair agreement is found with available pion-nucleus data, confirming the virtues of the NJL description of pion parton structure. We find sizable evolution effects on the shape of the distributions and on the generated average transverse momentum of the dilepton pair. We discuss the possibility of extracting details on pion unpolarized transverse momentum dependent parton distribution from pion nucleus DY data. In this respect, the region of low invariant mass of the lepton pair appears to be favored to discriminate between different descriptions of the non-perturbative pion transverse structure.

   hep-phEPJC(2018)·26 citations
10. 10*

    Complementarity for Dark Sector Bound States

    Gilly Elor🇺🇸 · Hongwan Liu🇺🇸 · Tracy R. Slatyer🇺🇸 · Yotam Soreq🇺🇸

    We explore the possibility that bound states involving dark matter particles could be detected by resonance searches at the LHC, and the generic implications of such scenarios for indirect and direct detection. We demonstrate that resonance searches are complementary to mono-jet searches and can probe dark matter masses above 1 TeV with current LHC data. We argue that this parameter regime, where the bound-state resonance channel is the most sensitive probe of the dark sector, arises most naturally in the context of non-trivial dark sectors with large couplings, nearly-degenerate dark-matter-like states, and multiple force carriers. The presence of bound states detectable by the LHC implies a minimal Sommerfeld enhancement that is appreciable, and potentially also radiative bound state formation in the Galactic halo, leading to large signals in indirect searches. We calculate these complementary constraints, which favor either models where the bound-state-forming dark matter constitutes a small fraction of the total density, or models where the late-time annihilation is suppressed at low velocities or late times. We present concrete examples of models that satisfy all these constraints and where the LHC resonance search is the most sensitive probe of the dark sector.

    hep-phastro-ph.COPRD(2018)·29 citations
11. 11*

    Resolving phenomenological problems with strongly-interacting-massive-particle models with dark vector resonances

    Soo-Min Choi🇰🇷 · Hyun Min Lee🇰🇷 · Pyungwon Ko🇰🇷 · Alexander Natale🇰🇷

    We consider a light dark matter candidate which is produced by the freeze-out mechanism with $3\to 2$ annihilations, the so called Strongly Interacting Massive Particles (SIMPs). SIMPs are identified as dark pions in dark chiral perturbation theory (ChPT) where both light mass and strong coupling needed for SIMPs can be realized by strong dynamics. In QCD-like theories with $SU(3{)}_L\times SU(3{)}_R/SU(3{)}_V$ flavor symmetry, including dark vector mesons in the hidden local symmetry scheme, we illustrate that dark vector mesons unitarize the dark ChPT efficiently, thus determine the correct relic density condition within the validity of the dark ChPT.

    hep-phPRD(2018)·66 citations
12. 12*

    A Multi-Component Model for the Observed Astrophysical Neutrinos

    Andrea Palladino🇩🇪 · Walter Winter🇩🇪

    We propose a multi-component model for the observed diffuse neutrino flux, including the residual atmospheric backgrounds, a Galactic contribution (such as from cosmic ray interactions with gas), an extra-galactic contribution from pp interactions (such as from starburst galaxies) and a hard extragalatic contribution from photo-hadronic interactions at the highest energies (such as from Tidal Disruption Events or Active Galactic Nuclei). We demonstrate that this model can address the key problems of astrophysical neutrino data, such as the different observed spectral indices in the high-energy starting and through-going muon samples, a possible anisotropy due to Galactic events, the non-observation of point sources, and the constraint from the extragalatic diffuse gamma-ray background. Furthermore, the recently observed muon track with a deposited energy of 4.5 PeV might be interpreted as evidence for the extragalactic photo-hadronic contribution. We perform the analysis based on the observed events instead of the unfolded fluxes by computing the probability distributions for the event type and reconstructed neutrino energy. As a consequence, we give the probability to belong to each of these astrophysical components on an event-to-event basis.

    ↳ astro-ph.HEhep-phAstron.Astrophys.(2018)·60 citations
13. 13*

    Towards Cosmological Dynamics from Loop Quantum Gravity

    Bao-Fei Li🇨🇳 · Parampreet Singh🇺🇸 · Anzhong Wang🇺🇸

    We present a systematic study of the cosmological dynamics resulting from an effective Hamiltonian, recently derived in loop quantum gravity using Thiemann's regularization and earlier obtained in loop quantum cosmology (LQC) by keeping the Lorentzian term explicit in the Hamiltonian constraint. We show that quantum geometric effects result in higher than quadratic corrections in energy density in comparison to LQC causing a non-singular bounce. Dynamics can be described by the Hamilton's or the Friedmann-Raychaudhuri equations, but the map between the two descriptions is not one-to-one. A careful analysis resolves the tension on symmetric versus asymmetric bounce in this model, showing that the bounce must be asymmetric and symmetric bounce is physically inconsistent, in contrast to the standard LQC. In addition, the current observations only allow a scenario where the pre-bounce branch is asymptotically de Sitter, similar to a quantization of the Schwarzschild interior in LQC, and the post-bounce branch yields the classical general relativity. For a quadratic potential, we find that a slow-roll inflation generically happens after the bounce, which is quite similar to what happens in LQC.

    ↳ gr-qcastro-ph.COhep-phhep-thPRD(2018)·90 citations
14. 14*

    Large-scale messengers from arbitrary spin fields

    Mohamed M. Anber🇺🇸

    We show that nonperturbative production of arbitrary spin fields from vacuum will accompany the generation of non-vanishing macroscopic energy-momentum tensor correlators. This argument is based on the general causal field formalism, which gives a manifestly covariant description of higher spin particles without any reference to gauge redundancy. Our findings are direct consequence of the Poincaré covariance and anlayticity of the Green's functions and independent of any detailed particle physics model. Further, we discuss the idea that any mechanism causing imbalance between the on-shell production of left- and right-handed fields leads to a helical structure in the energy momentum correlators and violation of the macroscopic parity symmetry. We check our method for fields with spin $\frac{1}{2}$ and show that it correctly reproduces previous results. However, the formalism suffers from pathologies related to non-localities that appear for massless particles with spin $\ge 1$ in flat space. We discuss the origin of these pathologies and the relevance of our findings to cosmology.

    ↳ hep-thastro-ph.COgr-qchep-phJHEP(2018)·2 citations
15. 15*

    Energy-Frontier Lepton-Hadron Collisions at CERN: the LHeC and the FCC-eh

    Masahiro Kuze🇯🇵

    Lepton-hadron colliders that use a proton or nucleus beam of current and future hadron colliders and let it collide with an electron beam from a newly built electron accelerator bring attractive physics programs which are strong and complementary to the hadron collider physics. Machine development for Energy Recovery LINAC and physics performance studies of such electron-hadron colliders, specifically the LHeC that uses the existing LHC beam and FCC-eh that is an option of Future Circular Collider program, are ongoing and reviewed in this article.

    ↳ hep-exhep-phphysics.acc-phInt.J.Mod.Phys.Conf.Ser.(2018)·9 citations
16. 16*

    Inertial Spontaneous Symmetry Breaking and Quantum Scale Invariance

    Pedro G. Ferreira🇬🇧 · Christopher T. Hill🇺🇸 · Graham G. Ross🇬🇧

    Weyl invariant theories of scalars and gravity can generate all mass scales spontaneously, initiated by a dynamical process of "inertial spontaneous symmetry breaking" that does not involve a potential. This is dictated by the structure of the Weyl current, $K_{\mu }$, and a cosmological phase during which the universe expands and the Einstein-Hilbert effective action is formed. Maintaining exact Weyl invariance in the renormalised quantum theory is straightforward when renormalisation conditions are referred back to the VEV's of fields in the action of the theory, which implies a conserved Weyl current. We do not require scale invariant regulators. We illustrate the computation of a Weyl invariant Coleman-Weinberg potential.

    ↳ hep-thgr-qchep-phPRD(2018)·86 citations
17. 17*

    Leptonic originated High energy neutrinos from astrophysical objects

    Arunava Bhadra🇮🇳 · Prabir Banik🇮🇳

    High-energy neutrinos are traditionally regarded as unambiguous signatures of hadronic cosmic rays in astrophysical environments. Here we show that TeV neutrinos can instead be produced by energetic electrons through purely electromagnetic processes in a variety of potential cosmic-ray accelerators. The resulting fluxes are comparable to those expected from hadronic interactions, suggesting that electrons may contribute a significant fraction of the neutrinos detected by the IceCube Observatory. These findings challenge the conventional interpretation of neutrino origins and underscore the need for joint gamma-ray and neutrino observations over a broad energy range to discriminate between hadronic and leptonic production mechanisms.

    ↳ astro-ph.HEhep-phJ.Phys.G(2026)·1 citation

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.