HEP Phenomenology·hep-ph

Mon·Dec 23, 2019Monday·December 23, 2019

45 papers—30 primary·15 cross-listed·reconstructed*

01*
Single Top Production in PDF fits
Emanuele R. Nocera🇳🇱 · Maria Ubiali🇬🇧 · Cameron Voisey🇬🇧
We study the impact of recent LHC $t$ -channel single top-quark and top-antiquark measurements at centre-of-mass energies of 7, 8 and 13 TeV on the parton distribution functions (PDFs) of the proton. We consider, namely, total cross sections, top-antitop cross section ratios, and differential distributions. We present a critical appraisal of the data, studying in particular how their description is affected by the theoretical details that enter the computation of the corresponding observables: QCD and electroweak higher-order corrections, the flavour scheme, and the value of the bottom-quark threshold. We perform a series of fits to the data within the NNPDF3.1 framework, whereby next-to-next-to-leading order QCD corrections are applied to single top measurements in a systematic way. We find that there exists an optimal combination of data that maximises consistency with the rest of the dataset, and efficiency in constraining the up, down and, partially, gluon PDFs.
hep-phhep-exJHEP(2020)·29 citations
02*
Determination of the Cabibbo-Kobayashi-Maskawa matrix element $∣ V_{c b} ∣$
Giulia Ricciardi🇮🇹 · Marcello Rotondo🇮🇹
In this review we present and discuss the determination of the magnitude of the Cabibbo-Kobayashi-Maskawa (CKM) matrix parameter $V_{c b}$ . The CKM matrix parametrizes the weak charged current interactions of quarks in the Standard Model (SM), and a precise determination of its elements has always been one of the most important targets of particle physics. The precise knowledge of the $∣ V_{c b} ∣$ value plays a pivotal role in testing the flavour sector of the SM and in the analyses of the unitarity of the CKM matrix. The SM does not predict the values of the CKM matrix elements, which have to be extracted by experimental data. Given the variety of channels that allow the extraction of $∣ V_{c b} ∣$ , different theoretical and experimental techniques are mustered for the $∣ V_{c b} ∣$ determination. The exertion toward precision represents not only a significant test of our theoretical procedures but a stimulus towards better detection performances. The most precise measurements of $∣ V_{c b} ∣$ come from semileptonic decays, that being tree level at the lowest order in the SM are generally considered unaffected by physics beyond the SM. After summarizing the characteristics of the SM that set the frame for the determination of $∣ V_{c b} ∣$ , we discuss inclusive and exclusive semileptonic $B$ decays. We analyze the $∣ V_{c b} ∣$ extraction methods and recent results, detailing both the theoretical and experimental techniques, and, finally, outline future prospects. We also comment on exclusive decays into heavy leptons, on the observables $R (D)$ and $R (D^{*})$ , on decays to excited $D$ meson states and on baryon decays.
hep-phhep-exJ.Phys.G(2020)·19 citations
03*
Isospin violating decay $D_{s}^{*} \to D_{s} π^{0}$ in chiral perturbation theory
Bin Yang🇨🇳 · Bo Wang🇨🇳 · Lu Meng🇨🇳 · Shi-Lin Zhu🇨🇳
We systematically calculate the isospin violating decay, $D_{s}^{*} \to D_{s} π^{0}$ , with the heavy meson chiral perturbation theory up to $O (p^{3})$ including the loop diagrams. The $O (p^{3})$ tree level amplitudes contain four undetermined LECs. We use two strategies to estimate them. With the nonanalytic dominance approximation, we get $Γ [D_{s}^{*} \to D_{s} π^{0}] = (3.38 \pm 0.12)$ eV. With the naturalness assumption, we give a possible range of the isospin violating decay width, $[1.11 - 6.88]$ eV. We find that the contribution of the $O (p^{3})$ corrections might be significant.
hep-phhep-exhep-latnucl-thPRD(2020)·10 citations
04*
Mining the Data Tables for Lorentz and CPT Violation
Neil Russell🇺🇸
In this conference proceedings, some comments on the present status and recent growth of efforts to find Lorentz and CPT violation are given by extracting metrics from the annually updated "Data Tables for Lorentz and CPT Violation." They reveal that tests span all the sectors of particle and gravitational physics, and have shown remarkable and consistent growth. Through numerous innovations and refinements in experiments, a large body of data has been amassed with ever-increasing precisions. The Tables are available through the Cornell preprint archive at arXiv:0801.0287.
hep-ph0 citations
05*
Fragmentation of Two Repelling Lund Strings
Cody B Duncan🇦🇺 · Peter Skands🇦🇺
Motivated by recent discoveries of flow-like effects in pp collisions, and noting that multiple string systems can form and hadronize simultaneously in such collisions, we develop a simple model for the repulsive interaction between two Lund strings with a positive (colour-oriented) overlap in rapidity. The model is formulated in momentum space and is based on a postulate of a constant net transverse momentum being acquired per unit of overlap along a common rapidity direction. To conserve energy, the strings shrink in the longitudinal direction, essentially converting a portion of the string invariant mass $m^{2}$ into $p_{⊥}^{2}$ for constant $m_{⊥}^{2} = m^{2} + p_{⊥}^{2}$ for each string. The reduction in string invariant mass implies a reduced overall multiplicity of produced hadrons; the increase in $p_{⊥}^{2}$ is local and only affects hadrons in the overlapping region. Starting from the simplest case of two symmetric and parallel strings with massless endpoints, we generalize to progressively more complicated configurations. We present an implementation of this model in the Pythia event generator and use it to illustrate the effects on hadron $p_{⊥}$ distributions and dihadron azimuthal correlations, contrasting it with the current version of the "shoving" model implemented in the same generator.
hep-phSciPost Phys.(2020)·8 citations
06*
Chiral effective theory of diquarks and the U_A(1) anomaly
Masayasu Harada🇯🇵 · Yan-Rui Liu🇨🇳 · Makoto Oka🇯🇵 · Kei Suzuki🇯🇵
The diquark is a strongly correlated quark pair that plays an important role in hadrons and hadronic matter. In order to treat the diquak as a building block of hadrons, we formulate an effective theory of diquark fields with $S U (3)_{R} \times S U (3)_{L}$ chiral symmetry. We concentrate on the scalar ( $0^{+}$ ) and pseudoscalar ( $0^{-}$ ) diquarks and construct a linear-sigma-model Lagrangian. It is found that the effective Lagrangian contains a new type of chirally symmetric meson-diquark-diquark coupling that breaks axial $U_{A} (1)$ symmetry. We discuss consequences of the $U_{A} (1)$ anomaly term to the diquark masses as well as to the singly heavy baryon spectrum, which is directly related to the diquark spectrum. We find an inverse mass ordering between strange and nonstrange diquarks. The parameters of the effective theory can be determined by the help of lattice QCD calculations of diquarks and also from the mass spectrum of the singly heavy baryons. We determine the strength of the $U_{A} (1)$ anomaly term, which is found to give a significant portion of the diquark masses.
hep-phPRD(2020)·31 citations
07*
Covariant derivative expansion for the renormalization of gravity
Rodrigo Alonso🇯🇵
The one loop UV divergences of Hilbert-Einstein gravity with a cosmological constant and spin 0, 1/2 and 1 matter are computed making use of a covariant derivative expansion and functional methods. For this purpose the transformation that yields the covariant derivative is extended to include a dynamical metric and the expansion in the fields themselves is made covariant which is relevant for the effective action due to the non-linear character of gravity
hep-phgr-qchep-thJHEP(2020)·11 citations
08*
TeV Scale Leptogenesis with Dark Matter in Non-standard Cosmology
Devabrat Mahanta🇮🇳 · Debasish Borah🇮🇳
We study the consequence of a non-standard cosmological epoch in the early universe on the generation of baryon asymmetry through leptogenesis as well as dark matter abundance. We consider two different non-standard epochs: one where a scalar field behaving like pressure-less matter dominates the early universe, known as early matter domination (EMD) scenario while in the second scenario, the energy density of the universe is dominated by a component whose energy density red-shifts faster than radiation, known as fast expanding universe (FEU) scenario. While a radiation dominated universe is reproduced by the big bang nucleosynthesis (BBN) epoch in both the scenario, the high scale phenomena like generation of baryon asymmetry and dark matter relic get significantly affected. Adopting a minimal particle physics framework known as the scotogenic model which generates light neutrino masses at one-loop level, we find that in one specific realisation of EMD scenario, the scale of leptogenesis can be lower than that in a standard cosmological scenario. The other non-standard cosmological scenarios, on the other hand, can be constrained from the requirement of successful low scale leptogenesis and generating correct dark matter abundance simultaneously. Such a low scale scenario not only gives a unified picture of baryon asymmetry, dark matter and origin of neutrino mass but also opens up interesting possibilities for experimental detection.
hep-phastro-ph.COJCAP(2020)·39 citations
09*
A Walking Dilaton Inflation
Hiroyuki Ishida🇯🇵 · Shinya Matsuzaki🇨🇳
We propose an inflationary scenario based on a many-flavor hidden QCD with eight flavors, which realizes the almost scale-invariant (walking) gauge dynamics. The theory predicts two types of composite (pseudo) Nambu-Goldstone bosons, the pions and the lightest scalar (dilaton) associated with the spontaneous chiral symmetry breaking and its simultaneous violation of the approximate scale invariance. The dilaton acts as an inflaton, where the inflaton potential is induced by the nonperturbative-scale anomaly linked with the underlying theory. The inflaton potential parameters are highly constrained by the walking nature, which are evaluated by straightforward nonperturbative analyses including lattice simulations. Due to the pseudo Nambu-Goldstone boson's natures and the intrinsic property for the chiral symmetry breaking in the walking gauge dynamics, the inflaton coupled to the pions naturally undergoes the small field inflation consistently with all the cosmological and astrophysical constraints presently placed by Planck 2018 data. When the theory is vector-likely coupled to the standard model in part in a way to realize a dynamical electroweak symmetry breaking, the reheating temperature is determined by the pion decays to electroweak gauge bosons. The proposed inflationary scenario would provide a dynamical origin for the small field inflation as well as the light pions as a smoking-gun to be probed by future experiments.
hep-phastro-ph.COhep-thPLB(2020)·16 citations
10*
Measurement of the weak mixing angle at a Super Charm-Tau factory with data-driven monitoring of the average electron beam polarization
A. Bondar🇷🇺 · A. Grabovsky🇷🇺 · A. Reznichenko🇷🇺 · A. Rudenko🇷🇺 · V. Vorobyev🇷🇺
A method for measuring the average longitudinal polarization of the electron beam at an electron-positron collider operating near the $J / ψ$ resonance is proposed. The method utilizes the differential cross-section of $J / ψ \to [Λ \to p π^{-}] [Λ ˉ \to p ˉ π^{+}]$ decay. It can be used to measure the average longitudinal polarization of electrons with the statistical precision better than $1 0^{- 3}$ at a Super Charm-Tau factory operating at the luminosity of $1 0^{35} cm^{- 2} s^{- 1}$ . The method is discussed in the context of the weak mixing angle measurement in the same experiment.
hep-phJHEP(2020)·17 citations
11*
A simplified connection between constituent quark and parton
Wei Zhu🇨🇳 · Fan Wang🇨🇳
We propose a simple way to connect Gell-Mann constituent quark model and Feynman parton model for the nucleon. Thus, we can dynamically understand a large amount of data for high energy hadronic processes starting from the first QCD principle.
hep-ph1 citation
12*
The decay $τ \to K^{* 0} (892) K^{-} ν_{τ}$ in the extended NJL model
M. K. Volkov🇷🇺 · A. A. Pivovarov🇷🇺 · K. Nurlan🇰🇿
In the extended Nambu -- Jona-Lasinio model, the decay width of $τ \to K^{* 0} (892) K^{-} ν_{τ}$ is calculated. The contributions from the contact diagram and diagrams with intermediate axial-vector, vector and pseudoscalar mesons in the ground and first radially excited states are taken into account. It is shown that axial-vector and vector channel with a contact diagram give a dominant contribution to the decay width. The obtained results for the decay width $τ \to K^{* 0} (892) K^{-} ν_{τ}$ are in satisfactory agreement with experimental data. A prediction for differential distribution over the invariant mass of the meson pair $K^{* 0} (892) K^{-}$ is given.
hep-phInt.J.Mod.Phys.A(2020)·7 citations
13*
Cho-Maison magnetic monopole: BPS limit and lower mass bound
Petr Beneš🇨🇿 · Filip Blaschke🇨🇿
We construct a class of effective extensions of the Standard Model that support finite-mass Cho-Maison magnetic monopole in the Bogomol'nyi-Prasad-Sommerfield (BPS) limit. We present an example of exact analytic monopole solution and derive a universal lower mass bound $M \geq 2 π v / g \approx 2.37 TeV$ of the Cho-Maison magnetic monopole.
hep-phhep-thJ.Phys.Conf.Ser.(2019)·2 citations
14*
New method for fitting coefficients in standard model effective theory
Geoffrey T. Bodwin🇺🇸 · Hee Sok Chung🇩🇪
We present an alternative method for carrying out a principal-component analysis of Wilson coefficients in standard model effective field theory (SMEFT). The method is based on singular-value decomposition (SVD). The SVD method provides information about the sensitivity of experimental observables to physics beyond the standard model that is not accessible in the Fisher-information method. In principle, the SVD method can also have computational advantages over diagonalization of the Fisher information matrix. We demonstrate the SVD method by applying it to the dimension-6 coefficients for the process of top-quark decay to a $b$ quark and a $W$ boson and use this example to illustrate some pitfalls in widely used fitting procedures. We also outline an iterative procedure for applying the SVD method to dimension-8 SMEFT coefficients.
hep-phPRD(2020)·5 citations
15*
Data-driven study of timelike Compton scattering
O. Grocholski🇵🇱 · H. Moutarde🇫🇷 · B. Pire🇫🇷 · P. Sznajder🇵🇱 · J. Wagner🇵🇱
In the framework of collinear QCD factorization, the leading twist scattering amplitudes for deeply virtual Compton scattering (DVCS) and timelike Compton scattering (TCS) are intimately related thanks to analytic properties of leading and next-to-leading order amplitudes. We exploit this welcome feature to make data-driven predictions for TCS observables to be measured in near future experiments. Using a recent extraction of DVCS Compton form factors from most of the existing experimental data for that process, we derive TCS amplitudes and calculate TCS observables only assuming leading-twist dominance. Artificial neural network techniques are used for an essential reduction of model dependency, while a careful propagation of experimental uncertainties is achieved with replica methods. Our analysis allows for stringent tests of the leading twist dominance of DVCS and TCS amplitudes. Moreover, this study helps to understand quantitatively the complementarity of DVCS and TCS measurements to test the universality of generalized parton distributions, which is crucial e.g. to perform the nucleon tomography.
hep-phhep-exnucl-exnucl-thEPJC(2020)·29 citations
16*
$τ \to μμμ$ at a rate of one out of $1 0^{14}$ tau decays?
Patrick Blackstone🇺🇸 · Matteo Fael🇩🇪 · Emilie Passemar🇺🇸
We present in a full analytic form the partial widths for the lepton flavour violating decays $μ^{\pm} \to e^{\pm} e^{+} e^{-}$ and $τ^{\pm} \to ℓ^{\pm} ℓ^{' +} ℓ^{' -}$ , with $ℓ, ℓ^{'} = μ, e$ , mediated by neutrino oscillations in the one-loop diagrams. Compared to the first result by Petcov in [1], obtained in the zero momentum limit $P ≪ m_{ν} ≪ M_{W}$ , we retain full dependence on $P$ , the momenta and masses of external particles, and we determine the branching ratios in the physical limit $m_{ν} ≪ P ≪ M_{W}$ . We show that the claim presented in [2] that the $τ \to ℓ ℓ^{'} ℓ^{'}$ branching ratios could be as large as $1 0^{- 14}$ , as a consequence of keeping the $P$ dependence, is flawed. We find rates of order $1 0^{- 55}$ , even smaller than those obtained in the zero momentum limit, as the latter prediction contains an unphysical logarithmic enhancement.
hep-phhep-exEPJC(2020)·48 citations
17*
Cosmic Ray Boosted Sub-GeV Gravitationally Interacting Dark Matter in Direct Detection
Wenyu Wang🇨🇳 · Lei Wu🇨🇳 · Jin Min Yang🇨🇳 · Hang Zhou🇨🇳 · Bin Zhu🇨🇳
Detections of non-gravitational interactions of massive dark matter (DM) with visible sector so far have given null results. The DM may communicate with the ordinary matter only through gravitational interaction. Besides, the majority of traditional direct detections have poor sensitivities for light DM because of the small recoil energy. Thanks to the high energy cosmic rays (CRs), the light DM can be boosted by scattering with CRs and thus may be detected in the ongoing experiments. In this work, we derive the exclusion limits on the cosmic ray boosted sub-GeV DM with gravitational mediator from the Xenon1T data. It turns out that a sizable region of such a cosmic ray boosted DM can be excluded by the current data.
hep-phastro-ph.COJHEP(2020)·82 citations
18*
String scale interacting dark matter from $π_{1}$
Andreas Mütter🇩🇪 · Patrick K.S. Vaudrevange🇩🇪
We show that in a wide class of string derived models of particle physics, heavy string modes with masses around the GUT scale can serve as a viable dark matter candidate. These heavy string modes wind around specific cycles in the extra-dimensional space, closely related to the fundamental group $π_{1}$ . As a consequence of a non-trivial $π_{1}$ , there is an exact discrete symmetry that stabilizes such winding strings. The dark matter candidate couples to the Standard Model via gravity and via the exchange of heavy string states. We find that, for reasonable values of the string coupling, our dark matter candidate can be produced in sizable amounts via freeze-in. Our scheme applies to many string constructions, including Calabi-Yau compactifications, and can be tested against constraints from the CMB.
hep-phhep-thJHEP(2020)·3 citations
19*
Resummation of double logarithms in loop-induced processes with effective field theory
Jian Wang🇨🇳
The large double logarithm in loop-induced processes is one kind of logarithm at subleading power, which has a different origin from Sudakov double logarithms. We develop a method with soft-collinear effective theory to resum these large double logarithms to all orders in the strong coupling constant.
hep-ph36 citations
20*
Pair production in temporally and spatially oscillating fields
Ivan A. Aleksandrov🇷🇺 · Christian Kohlfürst🇩🇪
Electron-positron pair production for inhomogeneous electric and magnetic fields oscillating in space and time is investigated. By employing accurate numerical methods (Furry-picture quantization and quantum kinetic theory), final particle momentum spectra are calculated and analyzed in terms of effective models. Furthermore, criteria for the applicability of approximate methods are derived and discussed. In this context, special focus is placed on the local density approximation, where fields are assumed to be locally homogeneous in space. Eventually, we apply our findings to the multiphoton regime. Special emphasis is on the importance of linear momentum conservation and the effect of its absence in momentum spectra within approximations based on local homogeneity of the fields.
hep-phphysics.comp-phPRD(2020)·58 citations
21*
Exploring the flavour structure of the high-scale MSSM
Gino Isidori🇨🇭 · Sokratis Trifinopoulos🇨🇭
We analyse the sensitivity of quark flavour-changing observables to the MSSM, in a regime of heavy superpartner masses. We analyse four distinct and motivated frameworks characterising the structure of the soft-breaking terms by means of approximate flavour symmetries. We show that a set of six low-energy observables with realistic chances of improvement in the near future, namely $Δ M_{s, d}$ , $ϵ_{K}$ , $ϵ_{K}^{'} / ϵ_{K}$ , $B (K \to π ν ν ˉ)$ , and the phase of $D$ -- $D ˉ$ mixing, could play a very important role in charactering these frameworks in a regime of superpartner masses up to $O (100)$ ~TeV. We show that these observables remain very interesting even in a long-term perspective, i.e.~even taking into account the direct mass reach of the most ambitious future high-energy colliders.
hep-phEPJC(2020)·5 citations
22*
Dimensional schemes for cross sections at NNLO
Christoph Gnendiger🇨🇭 · Adrian Signer🇨🇭
So far, the use of different variants of dimensional regularization has been investigated extensively for two-loop virtual corrections. We extend these studies to real corrections that are also required for a complete computation of physical cross sections at next-to-next-to-leading order. As a case study we consider two-jet production in electron-positron annihilation and describe how to compute the various parts separately in different schemes. In particular, we verify that using dimensional reduction the double-real corrections are obtained simply by integrating the four-dimensional matrix element over the phase space. In addition, we confirm that the cross section is regularization-scheme independent.
hep-phEPJC(2020)·7 citations
23*
NNLOPS description of the H $\to b b ˉ$ decay with MINLO
Wojciech Bizon🇩🇪 · Emanuele Re🇫🇷 · Giulia Zanderighi🇩🇪
We present an event generator that describes the Higgs boson decay into $b$ -quarks at next-to-next-to-leading-order (NNLO) in QCD and allows for a consistent matching to parton shower. For this purpose, we work within the POWHEG framework and employ the MINLO method to produce an NNLO-accurate H $\to b b ˉ$ event sample which can further be interfaced with a generic Higgs boson production mode. The resulting events, that combine Higgs production and decay, can be matched to parton shower by means of a vetoed shower. As an example, we present a short phenomenological study for associated Higgs production (HZ) and vector boson fusion (VBF) processes. We release the source code that was used to obtain these results as an $\text{h_bbg}$ user process in POWHEG-BOX-V2. We also provide tools that enable interfacing the decay events with events for an arbitrary Higgs production mode and subsequent matching of the combined Les Houches (LH) events with a parton shower.
hep-phhep-exJHEP(2020)·41 citations
24*
Off-shell vs on-shell modelling of top quarks in photon associated production
G. Bevilacqua🇭🇺 · H. B. Hartanto🇬🇧 · M. Kraus🇺🇸 · T. Weber🇩🇪 · M. Worek🇩🇪
We present a comparative study of various approaches for modelling of the $e^{+} ν_{e} μ^{-} ν ˉ_{μ} b b ˉ γ$ final state in $t t ˉ γ$ production at the LHC. Working at the NLO in QCD we compare the fully realistic description of the top quark decay chain with the one provided by the narrow-width-approximation. The former approach comprises all double, single and non-resonant diagrams, interferences, and off-shell effects of the top quarks. The latter incorporates only double resonant contributions and restricts the unstable top quarks to on-shell states. We confirm that for the integrated cross sections the finite top quark width effects are small and of the order of $O (Γ_{t} / m_{t})$ . We show, however, that they are strongly enhanced for more exclusive observables. In addition, we investigate fractions of events where the photon is radiated either in the production or in the decay stage. We find that large fraction of isolated photons comes from radiative decays of top quarks. Based on our findings, selection criteria might be developed to reduce such contributions, that constitute a background for the measurement of the anomalous couplings in the $t t ˉ γ$ vertex.
hep-phJHEP(2020)·51 citations
25*
Composite Higgs bosons from neutrino condensates in an inverted see-saw scenario
Leonardo Coito🇪🇸 · Carlos Faubel🇪🇸 · Arcadi Santamaria🇪🇸
We present a realization of the idea that the Higgs boson is mainly a bound state of neutrinos induced by strong four-fermion interactions. The conflicts of this idea with the measured values of the top quark and Higgs boson masses are overcome by introducing, in addition to the right-handed neutrino, a new fermion singlet, which, at low energies, implements the inverse see-saw mechanism. The singlet fermions also develop a scalar bound state which mixes with the Higgs boson. This allows us to obtain a small Higgs boson mass even if the couplings are large, as required in composite scalar scenarios. The model gives the correct masses for the top quark and Higgs boson for compositeness scales below the Planck scale and masses of the new particles above the electroweak scale, so that we obtain naturally a low-scale see-saw scenario for neutrino masses. The theory contains additional scalar particles coupled to the neutral fermions, which could be tested in present and near future experiments.
hep-phPRD(2020)·6 citations
26*
Precise prediction for the mass of the light MSSM Higgs boson for the case of a heavy gluino
Henning Bahl🇩🇪 · Ivan Sobolev🇩🇪 · Georg Weiglein🇩🇪
State-of-the-art predictions for the mass of the lightest MSSM Higgs boson usually involve the resummation of higher-order logarithmic contributions obtained within an effective-field-theory (EFT) approach, often combined with a fixed-order calculation into a hybrid result. For the phenomenologically interesting case of a significant hierarchy between the gluino mass and the masses of the scalar top quarks the predictions suffer from large theoretical uncertainties related to non-decoupling power-enhanced gluino contributions in the EFT results employing the $DR$ renormalisation scheme. We demonstrate that the theoretical predictions in the heavy gluino region are vastly improved by the introduction of a suitable renormalisation scheme for the EFT calculation. It is shown that within this scheme a recently proposed resummation of large gluino contributions is absorbed into the model parameters, resulting in reliable and numerically stable predictions in the heavy-gluino gluino region. We also discuss the integration of the results into the public code FeynHiggs.
hep-phPLB(2020)·27 citations
27*
Sensitivity to light sterile neutrinos at ESSnuSB
Monojit Ghosh🇸🇪 · Tommy Ohlsson🇸🇪 · Salvador Rosauro-Alcaraz🇪🇸
We present a comprehensive analysis in the 3+1 active-sterile neutrino oscillation scenario for the sensitivity of the ESSnuSB experiment in the presence of light sterile neutrinos assuming both a far (FD) and a near (ND) detector. Our analysis show that when the ND is included, the results are significantly different compared to the ones obtained with the FD only. We find that the capability of ESSnuSB to constrain the sterile mixing parameters is $sin^{2} 2 θ_{μ e} \sim 1 0^{- 4}$ for $Δ m^{2} = 1$ eV $^{2}$ if the ND is included and it becomes $sin^{2} 2 θ_{μ e} \sim 1 0^{- 2}$ without the ND. Furthermore, we show that the sensitivity can go down to $sin^{2} 2 θ_{μ e} \sim 1 0^{- 3}$ for the most conservative choice of the systematics on the ND. Comparing the sensitivity with T2HK, T2HKK, and DUNE by considering the FD only, we find that the sensitivity of ESSnuSB is smaller for most of the parameter space. Studying the CP violation sensitivity, we find that if the ND is included, it can be larger in the 3+1 scenario than in the standard one. However, if the ND is not included, the sensitivity is smaller compared to the one in the standard scenario. We also find that the CP violation sensitivity due to $δ_{13}$ is larger compared to the one induced by $δ_{24}$ . The sensitivities are slightly better for the dominant neutrino running ratio of ESSnuSB.
hep-phJHEP(2020)·23 citations
28*
Non-minimal (self-)running inflation: metric vs. Palatini formulation
Antonio Racioppi🇪🇪
We consider a model of quartic inflation where the inflaton is coupled non-minimally to gravity and the self-induced radiative corrections to its effective potential are dominant. We perform a comparative analysis considering two different formulations of gravity, metric or Palatini, and two different choices for the renormalization scale, widely known as prescription I and II. Moreover we comment on the eventual compatibility of the results with the final data release of the Planck mission.
hep-phastro-ph.COgr-qchep-thJHEP(2020)·51 citations
29*
New CTEQ global analysis of quantum chromodynamics with high-precision data from the LHC
Tie-Jiun Hou🇨🇳 · Jun Gao🇨🇳 · T. J. Hobbs🇺🇸 · Keping Xie🇺🇸 · Sayipjamal Dulat🇨🇳 · Marco Guzzi🇺🇸 · Joey Huston🇺🇸 · Pavel Nadolsky🇺🇸 · Jon Pumplin🇺🇸 · Carl Schmidt🇺🇸 · Ibrahim Sitiwaldi🇨🇳 · Daniel Stump🇺🇸 · C.-P. Yuan🇺🇸
We present the new parton distribution functions (PDFs) from the CTEQ-TEA collaboration, obtained using a wide variety of high-precision Large Hadron Collider (LHC) data, in addition to the combined HERA I+II deep-inelastic scattering data set, along with the data sets present in the CT14 global QCD analysis. New LHC measurements in single-inclusive jet production with the full rapidity coverage, as well as production of Drell-Yan pairs, top-quark pairs, and high- $p_{T}$ $Z$ bosons, are included to achieve the greatest sensitivity to the PDFs. The parton distributions are determined at NLO and NNLO, with each of these PDFs accompanied by error sets determined using the Hessian method. Fast PDF survey techniques, based on the Hessian representation and the Lagrange Multiplier method, are used to quantify the preference of each data set to quantities such as $α_{s} (m_{Z})$ , and the gluon and strange quark distributions. We designate the main resulting PDF set as CT18. The ATLAS 7 TeV precision $W / Z$ data are not included in CT18, due to their tension with other data sets in the global fit. Alternate PDF sets are generated including the ATLAS precision 7 TeV $W / Z$ data (CT18A), a new scale choice for low- $x$ DIS data (CT18X), or all of the above with a slightly higher choice for the charm mass (CT18Z). Theoretical calculations of standard candle cross sections at the LHC (such as the $g g$ fusion Higgs boson cross section) are presented.
hep-phhep-exnucl-thPRD(2021)·1013 citations
30*
The UV Fate of Anomalous $U (1)$ s and the Swampland
Nathaniel Craig🇺🇸 · Isabel Garcia Garcia🇺🇸 · Graham D. Kribs🇺🇸
Massive $U (1)$ gauge theories featuring parametrically light vectors are suspected to belong in the Swampland of consistent EFTs that cannot be embedded into a theory of quantum gravity. We study four-dimensional, chiral $U (1)$ gauge theories that appear anomalous over a range of energies up to the scale of anomaly-cancelling massive chiral fermions. We show that such theories require to be UV-completed at a finite cutoff below which a radial mode must appear, and cannot be decoupled -- a Stückelberg limit does not exist. When the infrared fermion spectrum contains a mixed $U (1)$ -gravitational anomaly, this class of theories provides a toy model of a boundary into the Swampland, for sufficiently small values of the vector mass. In this context, we show that the limit of a parametrically light vector comes at the cost of a quantum gravity scale that lies parametrically below $M_{P l}$ , and our result provides field theoretic evidence for the existence of a Swampland of EFTs that is disconnected from the subset of theories compatible with a gravitational UV-completion. Moreover, when the low energy theory also contains a $U (1)^{3}$ anomaly, the Weak Gravity Conjecture scale makes an appearance in the form of a quantum gravity cutoff for values of the gauge coupling above a certain critical size.
hep-phhep-thJHEP(2020)·26 citations
31*
De Sitter Diagrammar and the Resummation of Time
Matthew Baumgart🇺🇸 · Raman Sundrum🇺🇸
Light scalars in inflationary spacetimes suffer from logarithmic infrared divergences at every order in perturbation theory. This corresponds to the scalar field values in different Hubble patches undergoing a random walk of quantum fluctuations, leading to a simple toy "landscape" on superhorizon scales, in which we can explore questions relevant to eternal inflation. However, for a sufficiently long period of inflation, the infrared divergences appear to spoil computability. Some form of renormalization group approach is thus motivated to resum the log divergences of conformal time. Such a resummation may provide insight into De Sitter holography. We present here a novel diagrammatic analysis of these infrared divergences and their resummation. Basic graph theory observations and momentum power counting for the in-in propagators allow a simple and insightful determination of the leading-log contributions. One thus sees diagrammatically how the superhorizon sector consists of a semiclassical theory with quantum noise evolved by a first-order, interacting classical equation of motion. This rigorously leads to the "Stochastic Inflation" ansatz developed by Starobinsky to cure the scalar infrared pathology nonperturbatively. Our approach is a controlled approximation of the underlying quantum field theory and is systematically improvable.
↳ hep-thgr-qchep-phJHEP(2020)·104 citations
32*
Light meson spectroscopy at $e^{+} e^{-}$ machines
Beijiang Liu🇨🇳
The study of light hadrons is central to the understanding of confinement--a unique property of QCD. The quark model describs mesons as bound states of quarks and antiquarks. LQCD and QCD-motivated models for hadrons, however, predict a richer spectrum of mesons that takes into account not only the quark degrees of freedom but also the gluonic degrees of freedom. A selection of recent progress in the light-quark sector with unprecedented high-statistics data sets from $e^{+} e^{-}$ experiments are reviewed.
↳ hep-exhep-ph0 citations
33*
$Σ_{c} N$ interaction in chiral perturbation theory
Lu Meng🇨🇳 · Bo Wang🇨🇳 · Shi-Lin Zhu🇨🇳
We adopt the heavy baryon chiral perturbation theory to calculate the $Σ_{c} N$ interaction to the next-to-leading order. We consider the contact interactions, one-pion-exchange contributions, two-pion-exchange diagrams, and renormalization effects of the vertices, masses and wave functions. With the pion mass dependent expression, we fit the $Σ_{c} N$ interaction from HAL QCD calculation with $m_{π} \approx 410$ MeV and $m_{π} \approx 570$ MeV, and then extrapolate it to the physical pion mass. The $^{3} S_{1} (I = 1/2)$ $Σ_{c} N$ interaction is weakly attractive but no bound solution is found. We also propose a quark model to estimate the leading order $Σ_{c} N$ contact interaction with the $N N$ interaction as input. This approach combining the quark model and the chiral effective field theory predicts a very attractive interaction in $^{1} S_{0} (I = 3/2)$ $Σ_{c} N$ channel and a two-body bound state.
↳ nucl-thhep-lathep-phPRC(2020)·25 citations
34*
$S p (2 N)$ Yang-Mills towards large $N$
Jack Holligan🇬🇧 · Ed Bennett🇬🇧 · Deog Ki Hong🇰🇷 · Jong-Wan Lee🇰🇷 · C.-J. David Lin🇹🇼 · Biagio Lucini🇬🇧 · Maurizio Piai🇬🇧 · Davide Vadacchino🇮🇹
Non-perturbative aspects of the physics of $S p (2 N)$ gauge theories are interesting for phenomenological and theoretical reasons, and little studied so far, particularly in the approach to the large- $N$ limit. We examine the spectrum of glueballs and the string tension of Yang-Mills theories based upon these groups. Glueball masses are calculated numerically with a variational method from Monte-Carlo generated lattice gauge configurations. After taking continuum limits for $N$ = 1, 2, 3 and 4, we extrapolate the results towards large $N$ . We compare the resulting spectrum with that of $S U (N)$ gauge theories, both at finite $N$ and as $N$ approaches infinity.
↳ hep-lathep-phhep-thPoS(2019)·9 citations
35*
Constraining resonance properties through kaon production in pion-nucleus collisions at low energies
Vinzent Steinberg🇩🇪 · Jan Steinheimer🇩🇪 · Hannah Elfner🇩🇪 · Marcus Bleicher🇩🇪
Hadronic interactions are crucial for the dynamical description of heavy-ion reactions at low collision energies and in the late dilute stages at high collision energies. In particular, the properties and decay channels of resonances are an essential ingredient of hadronic transport approaches. The HADES collaboration measured particle production in collisions of pions with carbon and tungsten nuclei at $E_{kin} = 1.7 GeV$ . Such reactions are of high interest, because they allow to probe the properties of baryonic resonances produced in a much cleaner environment than the usual nucleus-nucleus collisions. We study these reactions with two transport approaches: SMASH (Simulating Many Accelerated Strongly-interacting Hadrons) and UrQMD (Ultra relativistic Quantum Molecular Dynamics) which follow the same underlying concept but with different implementations. The differential spectra in rapidity and transverse momentum are used to show how model parameters, as the decay channels of high mass resonances and angular distributions of kaon elastic scattering, can be constrained. It is found that the data favor the production of more particles with lower momentum over the production of few particles with higher momentum in these decays. In addition, the shape of the rapidity distribution of the kaons strongly depends on the angular distribution of the elastic kaon-nucleon cross section.
↳ nucl-thhep-phnucl-exJ.Phys.G(2021)·10 citations
36*
Gravitational-Wave Constraints on an Effective Field-Theory Extension of General Relativity
Noah Sennett🇩🇪 · Richard Brito🇩🇪 · Alessandra Buonanno🇩🇪 · Victor Gorbenko🇺🇸 · Leonardo Senatore🇺🇸
Gravitational-wave observations of coalescing binary systems allow for novel tests of the strong-field regime of gravity. Using data from the Gravitational Wave Open Science Center (GWOSC) of the LIGO and Virgo detectors, we place the first constraints on an effective field-theory based extension of General Relativity in which only higher-order curvature terms are added to the Einstein-Hilbert action. We construct gravitational-wave templates describing the quasi-circular, adiabatic inspiral phase of binary black holes in this extended theory of gravity. Then, after explaining how to properly take into account the region of validity of the effective field theory when performing tests of General Relativity, we perform Bayesian model selection using the two lowest-mass binary black-hole events reported to date by LIGO and Virgo -- GW151226 and GW170608 -- and constrain this theory with respect to General Relativity. We find that these data disfavors the appearance of new physics on distance scales around $\sim 150$ km. Finally, we describe a general strategy for improving constraints as more observations will become available with future detectors on the ground and in space.
↳ gr-qchep-phhep-thPRD(2020)·103 citations
37*
An update on moduli stabilization with antibrane uplift
Emilian Dudas🇫🇷 · Severin Lüst🇫🇷
It was recently shown that in warped compactifications based on a Klebanov-Strassler throat there is a light complex structure field, governing the size of the throat and the redshift at its tip. We show that after uplift of the cosmological constant by an anti-D3 brane at the tip of the throat, the contribution to supersymmetry breaking coming from the new light field is large. We work out the mass scales, in particular the condition for this field to be heavier than the Kähler modulus. We check that for the range of parameters relevant for the destabilization we find agreement with de Sitter swampland conjecture. Adding matter fields on distant branes, we discuss the effects on supersymmetry breaking in the observable sector. A hierarchically small scale of supersymmetry breaking translates generically into large values of localized D3 charges in the manifold.
↳ hep-thhep-phJHEP(2021)·54 citations
38*
Warm dark energy
Gianguido Dall'Agata🇮🇹 · Sergio Gonzalez-Martin🇮🇹 · Alexandros Papageorgiou🇺🇸 · Marco Peloso🇮🇹
Motivated by some of the recent swampland conjectures, we study the implementation for the late time acceleration of the Universe of a mechanism developed by Anber and Sorbo in the context of primordial inflation, in which an axion field can slowly roll in a steep potential due to additional friction provided by its coupling to some U(1) gauge field. We first study the realization of this mechanism in N = 2 supergravity models resulting from string compactifications on Calabi--Yau manifolds. We then study the transition between matter domination and the axion domination, and show that indeed the backreaction of the produced gauge field can sufficiently slow the motion of the axion, so to produce the present accelerated era. We finally study the transition from a pre-inflationary matter or radiation domination to primordial inflation. In the regime that we could explore numerically, the evolution is characterized by stages of faster axion roll (and consequent bursts of gauge field amplification) intermitted by stages of slower roll, with a pattern that "oscillates'' about the steady state Anber and Sorbo solution, but that does not appear to relax to it.
↳ hep-thastro-ph.COhep-phJCAP(2020)·62 citations
39*
Quantum mechanical path integrals in the first quantised approach to quantum field theory
James P. Edwards (IFM, UMSNH)🇲🇽 · Christian Schubert (IFM, UMSNH)🇲🇽
Perturbative quantum field theory usually uses second quantisation and Feynman diagrams. The worldline formalism provides an alternative approach based on first quantised particle path integrals, similar in spirit to string perturbation theory. Here we review the history, main features and present applications of the formalism. Our emphasis is on recent developments such as the path integral representation of open fermion lines, the description of colour using auxiliary worldline fields, incorporation of higher spin, and extension of the formalism to non-commutative space.
↳ hep-thhep-phquant-ph80 citations
40*
The Classical Symmetron Force in Casimir Experiments
Benjamin Elder🇬🇧 · Valeri Vardanyan🇳🇱 · Yashar Akrami🇫🇷 · Philippe Brax🇫🇷 · Anne-Christine Davis🇬🇧 · Ricardo S. Decca🇺🇸
The symmetron is a typical example of screened modified gravity, wherein the symmetron force is dynamically suppressed in dense environments. This allows it to hide in traditional tests of gravity. However, the past decade has seen great experimental progress towards measuring screened forces in the laboratory or in space. Screening relies on nonlinearities in the equation of motion, which significantly complicates the theoretical analysis of such forces. Here, we present a calculation of the symmetron force between a dense plate and sphere surrounded by vacuum. This is done via semi-analytical approaches in two limiting cases, based on the size of the sphere: large spheres are analyzed via the proximity force approximation, whilst small spheres are treated as screened test particles. In the intermediate regime we solve the problem numerically. Our results allow us to make contact with Casimir force experiments, which often employ a plate and sphere configuration for practical reasons, and may therefore be used to constrain symmetrons. We use our results to forecast constraints on the symmetron's parameters for a hypothetical Casimir experiment that is based on the current state of the art. The forecasts compare favorably to other leading laboratory tests of gravity, particularly atom interferometry and bouncing neutrons. We thus conclude that near-future Casimir experiments will be capable of placing tight new bounds on symmetrons. Our results for the symmetron force are derived in a scale-invariant way, such that although we here focus on Casimir experiments, they may be applied to any other plate-sphere system, ranging from microscopic to astrophysical scales.
↳ gr-qcastro-ph.COhep-phPRD(2020)·48 citations
41*
Direct determination of cosmic string loop density from simulations
Jose J. Blanco-Pillado🇪🇸 · Ken D. Olum🇺🇸
We determine the distribution of cosmic string loops directly from simulations, rather than determining the loop production function and inferring the loop distribution from that. For a wide range of loop lengths, the results agree well with a power law exponent -2.5 in the radiation era and -2 in the matter era, the universal result for any loop production function that does not diverge at small scales. Our results extend those of Ringeval, Sakellariadou, and Bouchet: we are able to run for 15 times longer in conformal time and simulate a volume 300-2400 times larger. At the times they reached, our simulation is in general agreement with the more negative exponents they found, -2.6 and -2.4. However, our simulations show that this was a transient regime; at later times the exponents decline to the values above. This provides further evidence against models with a rapid divergence of the loop density at small scales, such as ``model 3'' used to analyze LIGO data and predict LISA sensitivity.
↳ astro-ph.COgr-qchep-phPRD(2020)·44 citations
42*
Solving local anomaly equations in gauge-rank extensions of the Standard Model
B C Allanach🇬🇧 · Ben Gripaios🇬🇧 · Joseph Tooby-Smith🇬🇧
We consider local (or perturbative) gauge anomalies in models which extend the rank of the Standard Model (SM) gauge group and the chiral fermion content only by $n$ SM singlets. We give a general solution to the anomaly cancellation conditions (ACCs) of an additional $U (1)$ subgroup for the ACCs that involve only SM fermions and we examine whether a corresponding solution exists for the remaining ACCs. We show that a solution to the remaining ACCs always exists for $n \geq 5$ in the family non-universal case or $n \geq 3$ in the family-universal case. In the special case where only a single family carries non-vanishing charges, we find a general solution to all ACCs, for any value of $n$ .
↳ hep-thhep-phPRD(2020)·20 citations
43*
Double copy structure and the flat space limit of conformal correlators in even dimensions
Arthur Lipstein🇬🇧 · Paul McFadden🇬🇧
We analyse the flat space limit of 3-point correlators in momentum space for general conformal field theories in even spacetime dimensions, and show they exhibit a double copy structure similar to that found in odd dimensions. In even dimensions, the situation is more complicated because correlators contain branch cuts and divergences which need to be renormalised. We describe the analytic continuation of momenta required to extract the flat space limit, and show that the flat space limit is encoded in the leading singularity of a 1-loop triangle integral which serves as a master integral for 3-point correlators in even dimensions. We then give a detailed analysis of the renormalised correlators in four dimensions where the flat space limit of stress tensor correlators are controlled by the coefficients in the trace anomaly.
↳ hep-thhep-phPRD(2020)·82 citations
44*
Non-adiabatic cosmological production of ultra-light Dark Matter
Nathan Herring🇺🇸 · Daniel Boyanovsky🇺🇸 · Andrew R. Zentner🇺🇸
We study the non-adiabatic cosmological production of ultra light dark matter (ULDM) under a minimal set of assumptions: a free ultra light real scalar as a spectator field in its Bunch-Davies vacuum state during inflation and instantaneous reheating into a radiation dominated era. For (ULDM) fields minimally coupled to gravity, non-adiabatic particle production yields a \emph{distribution function} peaked at \emph{low} comoving momentum $N_{k} \propto 1/ k^{3}$ . The infrared behavior is a remnant of the infrared enhancement of light minimally coupled fields during inflation. We obtain the full energy momentum tensor, show explicity its equivalence with the fluid-kinetic one in the adiabatic regime, and extract the abundance, equation of state and free streaming length (cutoff in the matter power spectrum). Taking the upper bound on the scale of inflation from Planck, the (UDLM) saturates the dark matter abundance for $m ≃ 1.5 \times 1 0^{- 5} eV$ with an equation of state parameter $w ≃ 1 0^{- 14}$ and a free streaming length $λ_{f s} ≃ 70 pc$ . Thus this cosmologically produced (ULDM) yields a \emph{cold} dark matter particle. We argue that the abundance from non-adiabatic production yields a \emph{lower bound} on generic (ULDM) and axion-like particles that must be included in any assessment of (ULDM) as a dark matter candidate.
↳ gr-qcastro-ph.COhep-phhep-thPRD(2020)·50 citations
45*
LieART 2.0 -- A Mathematica Application for Lie Algebras and Representation Theory
Robert Feger🇩🇪 · Thomas W. Kephart🇺🇸 · Robert J. Saskowski🇺🇸
We present LieART 2.0 which contains substantial extensions to the Mathematica application LieART (Lie Algebras and Representation Theory) for computations frequently encountered in Lie algebras and representation theory, such as tensor product decomposition and subalgebra branching of irreducible representations. The basic procedure is unchanged: it computes root systems of Lie algebras, weight systems and several other properties of irreducible representations, but new features and procedures have been included to allow the extensions to be seamless. The new version of LieART continues to be user friendly. New extended tables of properties, tensor products and branching rules of irreducible representations are included in the supplementary material for use without Mathematica software. LieART 2.0 now includes the branching rules to special subalgebras for all classical and exceptional Lie algebras up to and including rank 15.
↳ hep-thhep-phmath-phmath.GR+2Comput.Phys.Commun.(2020)·147 citations

* 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.