HEP Phenomenology·hep-ph
28 papers—18 primary·10 cross-listed·reconstructed*
B. Ducloué🇫🇮 · T. Lappi🇫🇮 · Y. Zhu🇫🇮
In this talk, we report our recent progress on pinning down the cause of negativity in the NLO single inclusive hadron production in pA collisions at forward rapidity.
Ligong Bian🇨🇳 · Jing Shu🇨🇳 · Yongchao Zhang🇨🇳
The production is the primary channel to directly probe the triple gauge couplings. We analyze the process at the proposed Circular Electron-Positron Collider (CEPC), and find that the anomalous triple gauge couplings and relevant dimension six operators can be probed up to the order of . We also estimate constraints at the 14 TeV LHC, with both 300 fb and 3000 fb integrated luminosity from the leading lepton and azimuthal angle difference in the di-lepton channel. The constrain is somewhat weaker, up to the order of . The limits on the triple gauge couplings are complementary to those on the electroweak precision observables and Higgs couplings.
V. Cirigliano🇺🇸 · W. Dekens🇺🇸 · J. de Vries🇳🇱 · E. Mereghetti🇺🇸
Recent lattice QCD calculations of direct CP violation in decays indicate tension with the experimental results. Assuming this tension to be real, we investigate a possible beyond-the-Standard Model explanation via right-handed charged currents. By using chiral perturbation theory in combination with lattice QCD results, we accurately calculate the modification of induced by right-handed charged currents and extract values of the couplings that are necessary to explain the discrepancy, pointing to a scale around TeV. We find that couplings of this size are not in conflict with constraints from other precision experiments, but next-generation hadronic electric dipole moment searches (such as neutron and Ra) can falsify this scenario. We work out in detail a direct link, based on chiral perturbation theory, between CP violation in the kaon sector and electric dipole moments induced by right-handed currents which can be used in future analyses of left-right symmetric models.
Gavin P. Salam🇨🇭 · Lais Schunk🇫🇷 · Gregory Soyez🇫🇷
-subjettiness ratios are in wide use for tagging heavy boosted objects, in particular the ratio of 2-subjettiness to 1-subjettiness for tagging boosted electroweak bosons. In this article we introduce a new, \emph{dichroic} ratio, which uses different regions of a jet to determine the two subjettiness measures, emphasising the hard substructure for the 1-subjettiness and the full colour radiation pattern for the 2-subjettiness. Relative to existing -subjettiness ratios, the dichroic extension, combined with SoftDrop (pre-)grooming, makes it possible to increase the ultimate signal significance by about (for jets), or to reduce non-perturbative effects by a factor of at signal efficiency while maintaining comparable background rejection. We motivate the dichroic approach through the study of Lund diagrams, supplemented with resummed analytical calculations.
Peter Cox🇯🇵 · Alexander Kusenko🇯🇵 · Olcyr Sumensari🇫🇷 · Tsutomu T. Yanagida🇯🇵
It was previously noted that SU(5) unification can be achieved via the simple addition of light scalar leptoquarks from two split multiplets. We explore the parameter space of this model in detail and find that unification requires at least one leptoquark to have mass below TeV. We point out that introducing splitting of the allows the unification scale to be raised beyond GeV, while a U(1) symmetry can be imposed to forbid dangerous proton decay mediated by the light leptoquarks. The latest bounds from LHC searches are combined and we find that a leptoquark as light as 400 GeV is still permitted. Finally, we discuss the interesting possibility that the leptoquarks required for unification could also be responsible for the deviation observed in the ratio at LHCb.
Keith Pedersen🇺🇸 · Zack Sullivan🇺🇸
Two Higgs doublet extensions of the standard model, such as supersymmetry, predict the existence of charged Higgs bosons. We explore the reach for TeV-scale charged Higgs bosons through their associated production with top quarks, and their decay to boosted top jets and tagged boosted bottom jets, at a 14 TeV CERN Large Hadron Collider and at a 100 TeV Future Circular Collider. In particular, we show the moderate "wedge" region of parameter space cannot be probed at the Large Hadron Collider for TeV-scale because the cross section is too small. However, a 100 TeV future proton collider can close the wedge region below 2 TeV, and search for up to 6 TeV.
Jai More🇮🇳 · Asmita Mukherjee🇮🇳 · Sreeraj Nair🇮🇳
We calculate quark Wigner distributions using the light-front wave functions in a dressed quark model. In this model, a proton target is replaced by a simplified spin-1/2 state, namely a quark dressed with a gluon. We calculate the Wigner distributions for different polarization configuration of quark and the target state in this model.
Aqeel Ahmed🇩🇪 · Barry M. Dillon🇬🇧
The clockwork mechanism has recently been proposed as a natural way to generate hierarchies among parameters in quantum field theories. The mechanism is characterized by a very specific pattern of spontaneous and explicit symmetry breaking, and the presence of new light states referred to as `gears'. In this paper we begin by investigating the self-interactions of these gears in a scalar clockwork model and find a parity-like selection rule at all orders in the fields. We then proceed to investigate how the clockwork mechanism can be realized in 5D linear dilaton models from the spontaneous symmetry breaking of a complex bulk scalar field. We also discuss how the clockwork mechanism is manifest in the scalar components of 5D gauge theories in the linear dilaton model, and build their 4D deconstructed analogue. Finally we discuss attempts at building both 4D and 5D realizations of a non-abelian scalar clockwork mechanism, where in the latter we consider scenarios in which the Goldstone bosons arise from 5D scalar and 5D gauge fields.
Jong-Phil Lee🇰🇷 · Kang Young Lee🇰🇷
Inspired by the recent measurement of the decays by the CMS collaboration at the LHC, we study the lepton flavour-violating (LFV) decays in the general two Higgs doublet model. Those LFV interactions could accommodate the present deviation of the muon anomalous magnetic moment and also predict the LFV decay processes such as and . We find that the decay rates should be sizable with above experimental conditions in the framework of our model. These processes are expected to be observed at the colliders such as LHCb and Belle-II in the future.
The main aspects of chiral symmetry in QCD are presented. The necessity of its spontaneous breakdown is explained. Some low-energy theorems are reviewed. The role of chiral effective Lagrangians in the formulation and realization of chiral perturbation theory is emphasized. The consequences of the presence of anomalies are sketched.
P. Basler🇩🇪 · M. Krause🇩🇪 · M. Muhlleitner🇩🇪 · J. Wittbrodt🇩🇪 · A. Wlotzka🇩🇪
The discovery of the Higgs boson by the LHC experiments ATLAS and CMS has marked a milestone for particle physics. Yet, there are still many open questions that cannot be answered within the Standard Model (SM). For example, the generation of the observed matter-antimatter asymmetry in the universe through baryogenesis can only be explained qualitatively in the SM. A simple extension of the SM compatible with the current theoretical and experimental constraints is given by the 2-Higgs-Doublet Model (2HDM) where a second Higgs doublet is added to the Higgs sector. We investigate the possibility of a strong first order electroweak phase transition in the CP-conserving 2HDM type I and type II where either of the CP-even Higgs bosons is identified with the SM-like Higgs boson. The renormalisation that we apply on the loop-corrected Higgs potential allows us to efficiently scan the 2HDM parameter space and simultaneously take into account all relevant theoretical and up-to-date experimental constraints. The 2HDM parameter regions found to be compatible with the applied constraints and a strong electroweak phase transition are analysed systematically. Our results show that there is a strong interplay between the requirement of a strong phase transition and collider phenomenology with testable implications for searches at the LHC.
In [Phys. Rev. Lett. \textbf{117}, 213201 (2016)] we have determined the angular resolved and the total energy spectrum of a positron produced via nonlinear Breit-Wheeler pair production by a high-energy photon counterpropagating with respect to a tightly focused laser beam. Here, we first generalize the results in [Phys. Rev. Lett. \textbf{117}, 213201 (2016)] by including the possibility that the incoming photon is not exactly counterpropagating with respect to the laser field. As main focus of the present paper, we determine the photon angular resolved and total energy spectrum for the related process of nonlinear Compton scattering by an electron impinging into a tightly-focused laser beam. Analytical integral expressions are obtained under the realistic assumption that the energy of the incoming electron is the largest dynamical energy of the problem and that the electron is initially almost counterpropagating with respect to the laser field. The crossing symmetry relation between the two processes in a tightly focused laser beam is also elucidated.
Manfred Lindner🇩🇪 · Werner Rodejohann🇩🇪 · Xun-Jie Xu🇩🇪
We investigate the potential to probe new neutrino physics with future experiments measuring coherent neutrino-nucleus scattering. Experiments with high statistics should become feasible soon and allow to constrain parameters with unprecedented precision. Using a benchmark setup for a future experiment probing reactor neutrinos, we study the sensitivity on neutrino non-standard interactions and new exotic neutral currents (scalar, tensor, etc). Compared to Fermi interaction, percent and permille level strengths of the new interactions can be probed, superseding for some observables the limits from future neutrino oscillation experiments by up to two orders of magnitude.
Lin Chen🇨🇳 · Guang-You Qin🇨🇳 · Shu-Yi Wei🇨🇳 · Bo-Wen Xiao🇨🇳 · Han-Zhong Zhang🇨🇳
We develop the first systematic theoretical approach to dijet asymmetries in hadron-hadron collisions based on the perturbative QCD (pQCD) expansion and the Sudakov resummation formalism. We find that the pQCD calculation at next-to-leading order is indispensable to describe the experimental data, while the Sudakov resummation formalism is vital near the end points where the pQCD expansion fails to converge due to the appearance of large Sudakov logarithms. Utilizing our resummation improved pQCD approach, we obtain good agreement with the most up-to-date fully corrected ATLAS data on dijet asymmetry in collisions. Combining with the BDMPS jet energy loss formalism, we extract the value of jet transport coefficient - for the quark-gluon-plasma created in collisions at 2.76A TeV. This work paves the way for a more complete and deeper understanding of the properties of strongly-coupled QCD medium via the studies of dijet asymmetries in relativistic heavy-ion collisions.
With the experimental evidences of and decays, it is now possible to extract both tree and penguin amplitudes of the charmless two-body baryonic decays for the first time. The extracted penguin-tree ratio agrees with the expectation. Using the topological amplitude approach with the experimental results on and decay rates as input, predictions on all other , , and decay rates, where and are the low lying octet and decuplet baryons, respectively, are given. It is non-trivial that the results do not violate any existing experimental upper limit. From the analysis it is understandable that why and modes are the first two modes with experimental evidences. Relations on rates are verified using the numerical results. We note that the predicted rate is close to the experimental bound, which has not been updated in the last ten years. Direct asymmetries of all , , and modes are explored. Relations on asymmetries are examined using the numerical results. The direct asymmetry of decay can be as large as . The asymmetries of pure penguin modes are constrained to be of few . These modes are expected to be sensitive to New Physics contributions and are good candidates to be added to the list of the tests of the Standard Model.
Long-Gang Pang🇩🇪 · Kai Zhou🇩🇪 · Nan Su🇩🇪 · Hannah Petersen🇩🇪 · Horst Stöcker🇩🇪 · Xin-Nian Wang🇨🇳
Supervised learning with a deep convolutional neural network is used to identify the QCD equation of state (EoS) employed in relativistic hydrodynamic simulations of heavy-ion collisions from the simulated final-state particle spectra . High-level correlations of learned by the neural network act as an effective "EoS-meter" in detecting the nature of the QCD transition. The EoS-meter is model independent and insensitive to other simulation inputs, especially the initial conditions. Thus it provides a powerful direct-connection of heavy-ion collision observables with the bulk properties of QCD.
Renato M. Fonseca🇪🇸 · Martin Hirsch🇪🇸
We discuss contributions to neutrinoless double beta () decay involving vector bosons. The starting point is a list of all possible vector representations that may contribute to decay via or operators at tree-level. We then identify gauge groups which contain these vectors in the adjoint representation. Even though the complete list of vector fields that can contribute to up to is large (a total of 46 vectors), only a few of them can be gauge bosons of phenomenologically realistic groups. These latter cases are discussed in some more detail, and lower (upper) limits on gauge boson masses (mixing angles) are derived from the absence of decay.
Alexander Mück🇩🇪 · Lennart Oymanns🇩🇪
We use the POWHEG method to perform parton-shower matching for Drell-Yan production of W and Z bosons at the LHC at NLO QCD and NLO electroweak accuracy. In particular, we investigate an improved treatment of the vector-boson resonances within the POWHEG method. We employ an independent implementation of the POWHEG method and compare to earlier results within the POWHEGBOX. On the technical side, we provide the FKS formalism for photon-radiation off fermions within mass regularization.
Marcus Bluhm (North Carolina State U.)🇺🇸 · Marlene Nahrgang (SUBATECH, Nantes & Duke U.)🇫🇷 · Steffen A. Bass (Duke U.)🇺🇸 · Thomas Schaefer (North Carolina State U.)🇺🇸
The non-monotonic beam energy dependence of the higher cumulants of net-proton fluctuations is a widely studied signature of the conjectured presence of a critical point in the QCD phase diagram. In this work we study the effect of resonance decays on critical fluctuations. We show that resonance effects reduce the signatures of critical fluctuations, but that for reasonable parameter choices critical effects in the net-proton cumulants survive. The relative role of resonance decays has a weak dependence on the order of the cumulants studied with a slightly stronger suppression of critical effects for higher-order cumulants.
Jacques Marteau🇫🇷 · Jean de Bremond d'Ars🇫🇷 · Dominique Gibert🇫🇷 · Kevin Jourde🇫🇷 · Jean-Christophe Ianigro🇫🇷 · Bruno Carlus🇫🇷
Muography techniques applied to geological structures greatly improved in the past ten years. Recent applications demonstrate the interest of the method not only to perform structural imaging but also to monitor the dynamics of inner movements like magma ascent inside volcanoes or density variations in hydrothermal systems. Muography time-resolution has been studied thanks to dedicated experiments, e.g. in a water tower tank. This paper presents the activities of the DIAPHANE collaboration between particle- and geo-physicists and the most recent results obtained in the field of volcanology, with a focus on the main target, the Soufrière of Guadeloupe active volcano. Special emphasis is given on the monitoring of the dome's inner volumes opacity variations, that could be inferred to the hydrothermal system dynamics (vaporization of inner liquid water in coincidence with the appearance of new fumaroles at the summit). I also breifly present results obtained in the fields of civil engineering (study of urban underground tunnels) and archaelogy (greek tumulus scanning).
M. Boudaud🇫🇷 · E. F. Bueno🇧🇷 · S. Caroff🇫🇷 · Y. Genolini🇫🇷 · V. Poulin🇫🇷 · V. Poireau🇫🇷 · A. Putze🇫🇷 · S. Rosier🇫🇷 · P. Salati🇫🇷 · M. Vecchi🇧🇷
Two years ago, the AMS collaboration released the most precise measurement of the cosmic ray positron flux. It confirms that pure secondary predictions fall below the data above 10 GeV, suggesting the presence of a primary component, e.g. annihilations of WIMPs dark matter. Most analyses have focused on the high-energy part of the spectrum, disregarding the GeV energy region where cosmic ray transport is harder to model and solar modulation comes into play. Given the high quality of AMS measurements, it is timely to re-examine the positron anomaly over the entire energy range, taking into account transport processes so far neglected, e.g. convection or diffusive re-acceleration. We devise a new semi-analytical method to take into account transport processes so far neglected, but important below a few GeV. It is based on the pinching of inverse Compton and synchrotron energy losses inside the Galactic disc. It allows to carry out extensive scans over the cosmic ray propagation parameters, which we strongly constrain by requiring that the secondary component does not overshoot the AMS measurements. Only models with large diffusion coefficients survive this test. The positron flux is a powerful and independent probe of cosmic ray propagation, complementary to the boron-to-carbon ratio. We then scan over WIMP mass to fit the annihilation cross section and branching ratios, exploring both direct annihilations into standard model particles or through light mediators. In the former case, the best fit yields a -value of 0.4% for a mass of 264 GeV, a value that does not allow to reproduce the highest energy data points. Worse quality fits are found in the latter case. The interpretation of the positron excess in terms of single DM species annihilations is strongly disfavored. This conclusion is based solely on the positron data, and no other observation needs to be invoked.
James P. Vary🇺🇸 · Lekha Adhikari🇺🇸 · Guangyao Chen🇺🇸 · Meijian Li🇺🇸 · Yang Li🇺🇸 · Pieter Maris🇺🇸 · Wenyang Qian🇺🇸 · John R. Spence🇺🇸 · Shuo Tang🇺🇸 · Kirill Tuchin🇺🇸 · Xingbo Zhao🇨🇳
Quantitative calculations of the properties of hadrons and nuclei, with assessed uncertainties, have emerged as competitive with experimental measurements in a number of major cases. We may well be entering an era where theoretical predictions are critical for experimental progress. Cross-fertilization between the fields of relativistic hadronic structure and non-relativistic nuclear structure is readily apparent. Non-perturbative renormalization methods such as Similarity Renormalization Group and Okubo-Lee-Suzuki schemes as well as many-body methods such as Coupled Cluster, Configuration Interaction and Lattice Simulation methods are now employed and advancing in both major areas of physics. New algorithms to apply these approaches on supercomputers are shared among these areas of physics. The roads to success have intertwined with each community taking the lead at various times in the recent past. I briefly sketch these fascinating paths and comment on some symbiotic relationships. I also overview some recent results from the Hamiltonian Basis Light-Front Quantization approach.
Su-Jie Lin🇨🇳 · Xiao-Jun Bi🇨🇳 · Jie Feng🇨🇳 · Peng-Fei Yin🇨🇳 · Zhao-Huan Yu🇦🇺
Recently the AMS-02 collaboration has published the measurement of the cosmic antiproton to proton ratio and the flux with a high precision up to . In this work, we perform a systematic analysis of the secondary antiproton flux generated by the cosmic ray interaction with the interstellar gas. The uncertainty of the prediction originates from the cosmic ray propagation process and the hadronic interaction models. Although the cosmic ray propagation parameters have been well controlled by the AMS-02 ratio data for a specified model, different propagation models can not be discriminated by the data. The flux is also calculated for several hadronic interaction models, which are generally adopted by the cosmic ray community. However, the results for different hadronic models do not converge. We find the EPOS LHC model, which seems to fit the collider data very well, predicts a slightly lower ratio than the AMS-02 data at the high energy end. Finally we derive the constraints on the dark matter annihilation cross section from the AMS-02 ratio for different propagation and hadronic interaction models.
Shohei Saga🇯🇵 · Kouichirou Horiguchi🇯🇵 · Kiyotomo Ichiki🇯🇵
Cosmological defects result from cosmological phase transitions in the early Universe and the dynamics reflects their symmetry-breaking mechanisms. These cosmological defects may be probed through weak lensing effects because they interact with ordinary matters only through the gravitational force. In this paper, we investigate global textures by using weak lensing curl and B modes. Non-topological textures are modeled by the non-linear sigma model (NLSM), and induce not only the scalar perturbation but also vector and tensor perturbations in the primordial plasma due to the nonlinearity in the anisotropic stress of scalar fields. We show angular power spectra of curl and B modes from both vector and tensor modes based on the NLSM. Furthermore, we give the analytic estimations for curl and B mode power spectra. The amplitude of weak lensing signals depends on a combined parameter where and are the number of the scalar fields and the vacuum expectation value, respectively. We discuss the detectability of the curl and B modes with several observation specifications. In the case of the CMB lensing observation without including the instrumental noise, we can reach . This constraint is about 10 times stronger than the current one determined from the Planck. For the cosmic shear observation, we find that the signal-to-noise ratio depends on the mean redshift and the observing number of galaxies as and , respectively. In the study of textures using cosmic shear observations, the mean redshift would be one of the key design parameters.
Yong-Liang Ma🇨🇳 · Mannque Rho🇫🇷
It is shown that explicitly broken scale symmetry is essential for dense skyrmion matter in hidden local symmetry theory. Consistency with the vector manifestation fixed point for the hidden local symmetry of the lowest-lying vector mesons and the dilaton limit fixed point for scale symmetry in dense matter is found to require that the anomalous dimension () of the gluon field strength tensor squared () that represents the quantum trace anomaly should be .
The Pierre Auger Collaboration: A. Aab🇳🇱 · P. Abreu🇵🇹 · M. Aglietta🇮🇹 · I. Al Samarai🇫🇷 · I.F.M. Albuquerque🇧🇷 · I. Allekotte🇦🇷 · A. Almela🇦🇷 · J. Alvarez Castillo🇲🇽 · J. Alvarez-Muñiz🇪🇸 · G.A. Anastasi🇮🇹 · L. Anchordoqui🇺🇸 · B. Andrada🇦🇷 and 387 other authors
Simultaneous measurements of air showers with the fluorescence and surface detectors of the Pierre Auger Observatory allow a sensitive search for EeV photon point sources. Several Galactic and extragalactic candidate objects are grouped in classes to reduce the statistical penalty of many trials from that of a blind search and are analyzed for a significant excess above the background expectation. The presented search does not find any evidence for photon emission at candidate sources, and combined -values for every class are reported. Particle and energy flux upper limits are given for selected candidate sources. These limits significantly constrain predictions of EeV proton emission models from non-transient Galactic and nearby extragalactic sources, as illustrated for the particular case of the Galactic center region.
Alessandro Georgoudis🇸🇪 · Kasper J. Larsen🇬🇧 · Yang Zhang🇨🇭
For any given Feynman graph, the set of integrals with all possible powers of the propagators spans a vector space of finite dimension. We introduce the package {\sc Azurite} ({\bf A ZUR}ich-bred method for finding master {\bf I}n{\bf TE}grals), which efficiently finds a basis of this vector space. It constructs the needed integration-by-parts (IBP) identities on a set of generalized-unitarity cuts. It is based on syzygy computations and analyses of the symmetries of the involved Feynman diagrams and is powered by the computer algebra systems {\sc Singular} and {\sc Mathematica}. It can moreover analytically calculate the part of the IBP identities that is supported on the cuts.
Antonio Padilla🇬🇧 · David Stefanyszyn🇳🇱 · Toby Wilson🇬🇧
We investigate the soft behaviour of scalar effective field theories (EFTs) when there is a number of distinct derivative power counting parameters, . We clarify the notion of an enhanced soft limit and use these to extend the scope of on-shell recursion techniques for scalar EFTs. As an example, we perform a detailed study of theories with two power counting parameters, and , that include the shift symmetric generalised galileons. We demonstrate that the minimally enhanced soft limit uniquely picks out the Dirac-Born-Infeld (DBI) symmetry, including DBI galileons. For the exceptional soft limit we uniquely pick out the special galileon within the class of theories under investigation. We study the DBI galileon amplitudes more closely, verifying the validity of the recursion techniques in generating the six point amplitude, and explicitly demonstrating the invariance of all amplitudes under DBI galileon duality.
* 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.