Tue·Sep 3, 2019Tuesday·September 3, 2019

1. 01*

   Low-$Q^2$ empirical parametrizations of the $N^{\ast }$ helicity amplitudes

   G. Ramalho🇧🇷

   The data associated with the electromagnetic excitations of the nucleon (${\gamma }^{\ast }N\to N^{\ast }$) are usually parametrized by helicity amplitudes at the resonance $N^{\ast }$ rest frame. The properties of the ${\gamma }^{\ast }N\to N^{\ast }$ transition current at low $Q^2$ can be, however, better understood when expressed in terms of structure form factors, particularly near the pseudothreshold, when the magnitude of the photon three-momentum vanishes ($|\mathbf{q}|=0$). At the pseudothreshold the invariant four-momentum square became $q^2=(M_R-M_N{)}^2$, well in the timelike region $Q^2=-q^2<0$ [$M_N$ and $M_R$ are the mass of the nucleon and of the resonance, respectively]. In the helicity amplitude representation, the amplitudes have well-defined dependences on $|\mathbf{q}|$, near the pseudothreshold, and there are correlations between different amplitudes. Those constraints are often ignored in the empirical parametrizations of the helicity amplitudes. In the present work, we show that the structure of the transition current near the pseudothreshold has an impact on the parametrizations of the data. We present a method which modifies analytic parametrizations of the data at low $Q^2$, in order to take into account the constraints of the transition amplitudes near the pseudothreshold. The model dependence of the parametrizations on the low-$Q^2$ data is studied in detail.

   hep-phhep-exnucl-exnucl-thPRD(2019)·16 citations
2. 02*

   Inverse Radon transform and the transverse-momentum dependent functions

   I.V. Anikin🇷🇺 · L. Szymanowski🇵🇱

   We revisit the standard representation of the (inverse) Radon transform which is well-known in the mathematical literature. We extend this representation to the case involving the parton distributions. We have found the new additional contribution which is essentially related to the generalized transverse-momentum dependent parton distribution and double-distribution functions. We discuss the possible relationship of this term with the Sivers function.

   hep-phPRD(2019)·6 citations
3. 03*

   Improved pion mean fields and masses of singly heavy baryons

   June-Young Kim🇰🇷 · Hyun-Chul Kim🇰🇷

   A singly heavy baryon can be viewed as $N_c-1$ ($N_c$ as the number of colors) light valence quarks bound by the pion mean fields that are created by the presence of the $N_c-1$ valence quarks self-consistently, while the heavy quark inside a singly heavy baryon is regarded as a static color source. We investigate how the pion mean fields are created by the presence of $N_c$, $N_c-1$, and $N_c-2$ light valence quarks, which correspond to the systems of light baryons, singly heavy baryons, and doubly heavy baryons. As the number of color decreases from $N_c$ to $N_c-1$, the pion mean fields undergo changes. As a result, the valence-quark contributions to the moments of inertia of the soliton become larger than the case of the $N_c$ valence quarks, whereas the sea-quark contributions decrease systematically. On the other hand, the presence of the $N_c-2$ valence quarks is not enough to produce the strong pion mean fields, which leads to the fact that the classical soliton can not be formed. It indicates that the pion mean-field approach is not suitable to describe doubly heavy baryons. We show that the mass spectra of the singly heavy baryons are better described by the improved pion mean fields, compared with the previous work in which the pion mean fields are assumed to be intact with $N_c$ varied.

   hep-phhep-exnucl-thPTEP(2020)·15 citations
4. 04*

   V and heavy flavour production: status and recent theoretical developments

   Davide Napoletano🇫🇷

   In this talk, we review the status of the associated production of a vector boson and heavy flavour quarks, and some recent theoretical developments. While some aspects of these multiscale processes are not yet completely under control, a general understanding on how to treat them is emerging, thanks to many efforts to match a completely massless, with a completely massive approach.

   hep-phhep-exPoS(2019)·1 citation
5. 05*

   CKM matrix and FCNC suppression in $SO(5)\times U(1)\times SU(3)$ gauge-Higgs unification

   Shuichiro Funatsu🇨🇳 · Hisaki Hatanaka🇯🇵 · Yutaka Hosotani🇯🇵 · Yuta Orikasa🇨🇿 · Naoki Yamatsu🇯🇵

   The Cabibbo-Kobayashi-Maskawa (CKM) mixing matrix and flavor-changing neutral currents (FCNC's) in the quark sector are examined in the GUT inspired $SO(5)\times U(1)\times SU(3)$ gauge-Higgs unification in which the 4D Higgs boson is identified with the Aharonov-Bohm phase in the fifth dimension. Gauge invariant brane interactions play an important role for the flavor mixing in the charged-current weak interactions. The CKM matrix is reproduced except that the up quark mass needs to be larger than the observed one. FCNC's are naturally suppressed as a consequence of the gauge invariance, with a factor of order $10^{-6}$. It is also shown that induced flavor-changing Yukawa couplings are extremely small.

   hep-phPRD(2020)·21 citations
6. 06*

   A study of the corrections to factorization in ${\bar{B}}^0\to D^{\ast +}\omega {\pi }^{-}$

   S.I. Eidelman🇷🇺 · L.V. Kardapoltsev🇷🇺 · D.V. Matvienko🇷🇺

   A factorization hypothesis is tested by examining a form factor of the $\omega \pi$ production in hadronic $B^0\to D^{\ast \pm }\omega {\pi }^{\mp }$ decays. The form factor is compared to that from available $\tau$-lepton as well as $e^{+}{e}^{-}$ data using the conserved vector current hypothesis. The difference of normalizations of form factor shapes from $B$ and $\tau (e^{+}{e}^{-})$ data indicates the important role of the large $N_c$ limit in QCD. Moreover, the growth of the difference between the form factors with the $\omega \pi$ invariant mass is related to the perturbative QCD corrections of factorization. The current precision of $B$ data does not allow one to find any evidence of corrections to factorization. A promising study could be performed with the Belle II and LHCb data sets.

   hep-phJHEP(2020)·2 citations
7. 07*

   Relaxation time for quark spin and thermal vorticity alignment in heavy-ion collisions

   Alejandro Ayala🇲🇽 · David de la Cruz🇲🇽 · S. Hernández-Ortíz🇲🇽 · L. A. Hernández🇲🇽 · Jordi Salinas🇲🇽

   We compute the relaxation time for quark/antiquark spin and thermal vorticity alignment in a quark-gluon plasma at finite temperature and quark chemical potential. We model the interaction of quark/antiquark spin with thermal vorticity as driven by a phenomenological modification of the elementary quark interaction with gluons. We find that in a scenario where the angular velocity of the quark-gluon plasma produced in a peripheral heavy-ion collision is small, quarks/antiquarks take a long time to align their spin with the vorticity. However, when the angular velocity created in the reaction is large, the alignment is efficient and well within the lifetime of the system created in the reaction. The relaxation time is larger for antiquarks which points out to a difference for the polarization of hadrons and antihadrons when this alignment is preserved during hadronization.

   hep-phnucl-thPLB(2020)·38 citations
8. 08*

   Coupled-channel approach in hadron-hadron scattering

   J.A. Oller🇪🇸

   Coupled-channel dynamics for scattering and production processes in partial-wave amplitudes is discussed from a perspective that emphasizes unitarity and analyticity. We elaborate on several methods that have driven to important results in hadron physics, either by themselves or in conjunction with effective field theory. We also develop and compare with the use of the Lippmann-Schwinger equation in near-threshold scattering. The final(initial)-state interactions are discussed in detail for the elastic and coupled-channel case. Emphasis has been put in the derivation and discussion of the methods presented, with some applications examined as important examples of their usage.

   hep-phcond-mat.quant-gasnucl-thPPNP(2020)·77 citations
9. 09*

   Multiplicity fluctuations in the Glauber Monte Carlo approach

   Maksym Deliyergiyev🇵🇱 · Maciej Rybczynski🇵🇱

   We discuss multiplicity fluctuations of charged particles produced in nuclear collisions measured event-by-event by the NA49 experiment at CERN SPS within the Glauber Monte Carlo approach. We use the concepts of wounded nucleons and wounded quarks in the mechanism of multiparticle production to characterize multiplicity fluctuations expressed by the scaled variance of multiplicity distribution. Although Wounded Nucleon Model correctly reproduce the centrality dependence of the average multiplicity in Pb+Pb collisions, it completely fails in description of corresponding centrality dependence of scaled variance of multiplicity distribution. Using subnucleonic degrees of freedom, i.e. wounded quarks within Wounded Quark Model, it is possible to describe quite well the multiplicity distribution of charged particles produced in proton+proton interactions. However, the Wounded Quark Model with parameters describing multiplicity distribution of particles produced in proton+proton interactions substantially exceeds the average multiplicity of charged particles produced in Pb+Pb collisions. To obtain values of average multiplicities close to those experimentally measured in Pb+Pb collisions, the concept of shadowed quark sources is implemented. Wounded Quark Model with implemented shadowing source scenario reproduces the centrality dependence of scaled variance of multiplicity distribution of charged particles produced in Pb+Pb collisions in the range from the most central to mid-peripheral interactions.

   hep-phnucl-thPRC(2020)·6 citations
10. 10*

    Scalar leptoquark effects on $B\to \mu \bar{\nu }$ decay

    Wei-Shu Hou🇹🇼 · Tanmoy Modak🇹🇼 · Gwo-Guang Wong🇹🇼

    Purely leptonic $B$ meson decays provide unique probes for physics Beyond the Standard Model. We study the impact of a scalar leptoquark, $S_1$, on $B\to \mu \bar{\nu }$ decay. We find that, for $m_{S_1}\sim 1$ TeV, the $S_1$ leptoquark can modify the $B\to \mu \bar{\nu }$ rate significantly. Such a leptoquark can in prinicple also alter the $B\to \tau \bar{\nu }$ rate. However, current searches from LHC and low energy physics provide some constraints on the parameter space.

    hep-phhep-exEPJC(2019)·10 citations
11. 11*

    Recent QCD results from the xFitter project: Probing the strange content of the proton with charm production in charged current at LHeC

    xFitter Developers Team: Hamed Abdolmaleki🇮🇷 · Valerio Bertone🇮🇹 · Daniel Britzger🇩🇪 · Stefano Camarda🇨🇭 · Amanda Cooper-Sarkar🇬🇧 · Achim Geiser🇩🇪 · Francesco Giuli🇮🇹 · Alexander Glazov🇩🇪 · Agnieszka Luszczak🇵🇱 · Ivan Novikov🇷🇺 · Fred Olness🇺🇸 · Andrey Sapronov🇷🇺 · Oleksandr Zenaiev🇩🇪

    We investigate charm production in charged-current deep-inelastic scattering (DIS) using the xFitter program. xFitter is an open-source software framework for the determination of PDFs and the analysis of QCD physics, and has been used for a variety of LHC studies. The study of charged current DIS charm production provides an important perspective on the strange quark PDF, s(x). We make use of the xFitter tools to study the present s(x) constraints, and then use LHeC pseudodata to infer how these might improve. Furthermore, as xFitter implements both Fixed Flavor and Variable Flavor number schemes, we can examine the impact of these different theoretical choices; this highlights some interesting aspects of multi-scale calculations. This study provides a practical illustration of the many features of xFitter.

    hep-phPoS(2019)·1 citation
12. 12*

    nCTEQ PDFs at the LHC: Vector boson production in heavy ion collisions

    The nCTEQ Collaboration: D. B. Clark🇺🇸 · E. Godat🇺🇸 · T. J. Hobbs🇺🇸 · T. Ježo🇨🇭 · J. Kent🇺🇸 · C. Keppel🇺🇸 · M. Klasen🇩🇪 · K. Kovarík🇩🇪 · A. Kusina🇵🇱 · F. Lyonnet🇺🇸 · J.G. Morfin🇺🇸 · F. I. Olness🇺🇸 and 3 other authors

    Extraction of the strange quark PDF is a long-standing puzzle. We use the nCTEQ nPDFs with uncertainties to study the impact of the LHC W/Z production data on both the flavor differentiation and nuclear corrections; this complements the information from neutrino-DIS data. As the proton flavor determination is dependent on nuclear corrections (from heavy target DIS, for example), LHC heavy ion measurements can also help improve proton PDFs. We introduce a new implementation of the nCTEQ code (nCTEQ++) based on C++ which has a modular strucure and enables us to easily integrate programs such as HOPPET, APPLgrid, and MCFM. Using ApplGrids generated from MCFM, we use nCTEQ++ to perform a preliminary fit including the pPb LHC W/Z vector boson data.

    hep-phPoS(2019)·3 citations
13. 13*

    General COHERENT Constraints on Neutrino Non-Standard Interactions

    C. Giunti🇮🇹

    We present the results of a systematic study of the constraints on neutrino neutral-current non-standard interactions (NSI) that can be obtained from the analysis of the COHERENT spectral and temporal data. First, we consider the general case in which all the ten relevant neutral-current NSI parameters are considered as free. We show that they are very weakly constrained by the COHERENT data because of possible cancellations between the up and down quark contributions. However, the up-down average parameters are relatively well constrained and the strongest constraints are obtained for an appropriate linear combination of up and down NSI parameters. We also consider the case in which there are only NSI with either up or down quarks, and we show that the LMA-Dark fit of solar neutrino data is excluded at $5.6\sigma$ and $7.2\sigma$ respectively, for NSI with up and down quark. We finally present the tight constraints that can be obtained on each NSI parameter if it is the dominant one, assuming that the effects of the others are negligible.

    hep-phhep-exPRD(2020)·124 citations
14. 14*

    The Role of the $t\bar{t}h$ Rest Frame in Direct Top-Quark Yukawa Coupling Measurements

    Andrea Ferroglia🇺🇸 · Miguel C. N. Fiolhais🇺🇸 · Emanuel Gouveia🇵🇹 · António Onofre🇵🇹

    This paper studies new possibilities to directly measure a hypothetical $CP$-odd (pseudoscalar) component in the top-quark Yukawa coupling. In particular, the role of the $t\bar{t}h$ center-of-mass rest frame in the associated production of a top pair and a $h$ boson at the LHC is explored. The $h$ boson is assumed to have both a $CP$-even (scalar) and a $CP$-odd coupling to the top quark. The relative strength of the scalar and pseudoscalar components is regulated by an angle $\alpha$. Observables sensitive to the nature of the top-quark Yukawa coupling are proposed. These observables are defined in terms of the transverse and longitudinal projections of $t$, $\bar{t}$ and $h$ momenta with respect to the beam axis in the $t\bar{t}h$ rest frame. Distributions differential with respect to those observables are evaluated up to NLO in QCD. These distributions are found to be sensitive to the $CP$ nature of the coupling. Dileptonic final states of the $t\bar{t}h$ system (with $h\to b\bar{b}$) are used, after fast DELPHES detector simulation and full event reconstruction through a kinematic fit, as a case study to test the observables' sensitivity to the $CP$ nature of the coupling. Confidence levels are presented as a function of the total integrated LHC luminosity for the case of exclusion of a pure $CP$-odd coupling against the Standard Model $CP$-even hypothesis. By using observables evaluated in the $t\bar{t}h$ system, the luminosity needed to directly probe the $CP$ properties of the top-quark Yukawa coupling at the High-Luminosity run of the LHC can be decreased by a few hundred inverse femtobarns, when compared to analyses that use observables in the laboratory rest frame. In addition, transverse momentum distributions of the $h$ boson and top quarks are found to provide no more discriminant power than a counting experiment.

    hep-phPRD(2019)·26 citations
15. 15*

    Constraining the top quark effective field theory using the top quark pair production in association with a jet at future lepton colliders

    Reza Jafari🇮🇷 · Parvin Eslami🇮🇷 · Mojtaba Mohammadi Najafabadi🇮🇷 · Hamzeh Khanpour🇮🇷

    Our main aim in this paper is to constrain the effective field theory describing the top quark couplings through the $e^{-}{e}^{+}\to t\bar{t}+$jet process. The analysis is carried out considering two different center-of-mass energies of 500 and 3000 GeV including a realistic simulation of the detector response and the main sources of background processes. The expected limits at 95\% CL are derived on the new physics couplings such as $t\bar{t}\gamma$, $t\bar{t}Z$, and $t\bar{t}g$ for each benchmark scenario using the dileptonic $t\bar{t}$ final state. We show that the 95\% CL limits on dimensionless Wilson coefficients ${\bar{c}}_i$ considered in this analysis could be probed down to $10^{-4}$.

    hep-phPLB(2020)·7 citations
16. 16*

    Study of the sensitivity to CKM angle $\gamma$ under simultaneous determination from multiple $B$ meson decay modes

    J. Garra Ticó🇬🇧 · V. Gibson🇬🇧 · S. C. Haines🇬🇧 · C. R. Jones🇬🇧 · M. Kenzie🇬🇧 · G. Lovell🇬🇧

    Several methods exist to measure $CP$ violation observables related to the CKM unitarity triangle angle $\gamma$ using $B$ meson decays. These observables are different for every $B$ meson decay considered, although the information they contain on $\gamma$ is encoded in a similar way for all of them. This paper describes a strategy for a simultaneous measurement of $\gamma$ using several $B$ meson decays that takes into account possible correlations between them. Sensitivity studies demonstrate that the simultaneous analysis of several $B$ meson decay modes results in smaller uncertainties and improved statistical behaviour compared to a combination of standalone measurements.

    hep-phPRD(2020)·11 citations
17. 17*

    Temperatures and chemical potentials at kinetic freeze-out in relativistic heavy ion collisions from coarse grained transport simulations

    Gabriele Inghirami🇫🇮 · Paula Hillmann🇩🇪 · Boris Tomášik🇸🇰 · Marcus Bleicher🇩🇪

    Using the UrQMD/coarse graining approach we explore the kinetic freeze-out stage in central Au + Au collisions at various energies. These studies allow us to obtain detailed information on the thermodynamic properties (e.g. temperature and chemical potential) of the system during the kinetic decoupling stage. We explore five relevant collision energies in detail, ranging from $\sqrt{s_{NN}}=2.4\mathrm{GeV}$ (GSI-SIS) to $\sqrt{s_{NN}}=200\mathrm{GeV}$ (RHIC). By adopting a standard Hadron Resonance Gas equation of state, we determine the average temperature $⟨T⟩$ and the average baryon chemical potential $⟨{\mu }_{\mathrm{B}}⟩$ on the space-time hyper-surface of last interaction. The results highlight the nature of the kinetic freeze-out as a continuous process. This differential decoupling is an important aspect often missed when summarizing data as single points in the phase diagram as e.g. done in Blast-Wave fits. We compare the key properties of the system derived by using our approach with other models and we briefly review similarities and differences.

    hep-phnucl-exnucl-thJ.Phys.G(2020)·15 citations
18. 18*

    The Price of Tiny Kinetic Mixing

    Tony Gherghetta🇺🇸 · Joern Kersten🇳🇴 · Keith Olive🇺🇸 · Maxim Pospelov🇺🇸

    We consider both "bottom-up" and "top-down" approaches to the origin of gauge kinetic mixing. We focus on the possibilities for obtaining kinetic mixings $ϵ$ which are consistent with experimental constraints and are much smaller than the naive estimates ($ϵ\sim 10^{-2}-10^{-1}$) at the one-loop level. In the bottom-up approach, we consider the possible suppression from multi-loop processes. Indeed we argue that kinetic mixing through gravity alone, requires at least six loops and could be as large as $\sim 10^{-13}$. In the top-down approach we consider embedding the Standard Model and a $U(1{)}_X$ in a single grand-unified gauge group as well as the mixing between Abelian and non-Abelian gauge sectors.

    hep-phPRD(2019)·136 citations
19. 19*

    Relating amplitude and PDF factorisation through Wilson-line geometries

    Giulio Falcioni🇬🇧 · Einan Gardi🇬🇧 · Calum Milloy🇬🇧

    We study long-distance singularities governing different physical quantities involving massless partons in perturbative QCD by using factorisation in terms of Wilson-line correlators. By isolating the process-independent hard-collinear singularities from quark and gluon form factors, and identifying these with the ones governing the elastic limit of the perturbative Parton Distribution Functions (PDFs) -- $\delta (1-x)$ in the large-$x$ limit of DGLAP splitting functions -- we extract the anomalous dimension controlling soft singularities of the PDFs, verifying that it admits Casimir scaling. We then perform an independent diagrammatic computation of the latter using its definition in terms of Wilson lines, confirming explicitly the above result through two loops. By comparing our eikonal PDF calculation to that of the eikonal form factor by Erdogan and Sterman and the classical computation of the closed parallelogram by Korchemsky and Korchemskaya, a consistent picture emerges whereby all singularities emerge in diagrammatic configurations localised at the cusps or along lightlike lines, but where distinct contributions to the anomalous dimensions are associated with finite (closed) lightlike segments as compared to infinite (open) ones. Both are relevant for resumming large logarithms in physical quantities, notably the anomalous dimension controlling Drell-Yan or Higgs production near threshold on the one hand, and the gluon Regge trajectory controlling the high-energy limit of partonic scattering on the other.

    hep-phhep-thJHEP(2019)·37 citations
20. 20*

    Light scalar $K_0^{\ast }(700)$ meson in vacuum and a hot medium

    K. Azizi🇮🇷 · B. Barsbay🇹🇷 · H. Sundu🇹🇷

    The $K_0^{\ast }(700)$ meson appears as the lightest strange scalar meson in PDG. Although there were a lot of experimental and theoretical efforts to establish this particle and determine its properties and nature, it still needs confirmation in an experiment and its internal quark-gluon organization needs to be clarified. In this connection, we study some spectroscopic properties of this state in a hot medium as well as a vacuum by modeling it as a usual meson of a quark and an aniquark. In particular, we investigate its mass and coupling or decay constant in terms of the temperature of a hot medium by including the medium effects by the fermionic and gluonic parts of the energy momentum tensor as well as the temperature-dependent continuum threshold, quark, gluon and mixed condensates. We observe that the mass of $K_0^{\ast }(700)$ remains unchanged up to $T\simeq 0.6T_c$ with $T_c$ being the critical temperature, but it starts to diminish after this point and approaches zero near to the critical temperature referring to the melting of the meson. The coupling of $K_0^{\ast }(700)$ is also sensitive to $T$ at higher temperatures. It starts to grow rapidly after $T\simeq 0.85T_c$. We turn off the medium effects and calculate the mass and coupling of the $K_0^{\ast }(700)$ state at zero temperature. The obtained mass is in accord with the average Breit-Wigner mass value reported by PDG.

    hep-phhep-exhep-latPRD(2019)·9 citations
21. 21*

    Higgs-Boson Masses and Mixings in the MSSM with CP Violation and Heavy SUSY Particles

    Nick Murphy🇩🇰 · Heidi Rzehak🇩🇰

    We calculate the Higgs-boson mass spectrum and the corresponding mixing of the Higgs states in the Minimal Supersymmetric Standard Model (MSSM). We assume a mass-hierarchy with heavy SUSY particles and light Higgs bosons. To investigate this scenario, we employ an effective-field-theory approach with a low-energy Two-Higgs-Doublet Model (2HDM) where both Higgs doublets couple to up- as well as down-type fermions. We perform a one-loop matching of the MSSM to the 2HDM and evolve the parameters to the low energy scale by exploiting two-loop renormalization group equations, taking the complex parameters into account. For the calculation of the pole mass, we compare three different options: one suitable for large charged Higgs masses, one for low charged Higgs masses, and one approximation that interpolates between these scenarios. The phase dependence of the mass of the lightest neutral Higgs boson can be sizeable, i.e. on the order of a couple of GeV depending on the scenario. In addition, we discuss the CP composition of the neutral Higgs bosons.

    hep-phEPJC(2022)·20 citations
22. 22*

    Fermion mass splitting in the technicolor coupled scenario

    A. Doff🇧🇷 · A. A. Natale🇧🇷

    We discuss fermion mass generation in unified models where QCD and technicolor (or any two strongly interacting theories) have their Schwinger-Dyson equations coupled. In this case the technicolor (TC) and QCD self-energies are modified in comparison with the behavior observed in the isolated theories. In these models the pseudo-Goldstone boson masses are much higher than the ones obtained in different contexts, and phenomenological signals, except from a light scalar composite boson, will be quite difficult to be observed at present collider energies. The most noticeable fact of these models is how the mass splitting between the different ordinary fermions is generated. We discuss how a necessary horizontal (or family) symmetry can be implemented in order to generate the mass splitting between fermions of different generations; how the fermionic mass spectrum may be modified due to GUT interactions, as well as how the mass splitting within the same fermionic generation are generated due to electroweak and GUT interactions.

    hep-phEPJC(2020)·3 citations
23. 23*

    Seesaw neutrinos with one right-handed singlet field and a second Higgs doublet

    D. Jurčiukonis🇱🇹 · T. Gajdosik🇱🇹 · A. Juodagalvis🇱🇹

    We study parameters of an extension of the Standard Model. The neutrino sector is enlarged by one right-handed singlet field, allowing for the seesaw mechanism type-I, and the Higgs sector contains one additional doublet, which contributes to light neutrino masses through one-loop radiative corrections. Employing an approximation for the effective light neutrino mass matrix we express the masses of the light neutrinos analytically, allowing us to parametrize the Yukawa couplings to neutrinos by the experimental measurements on the neutrino sector and only two free parameters. We focus on a CP-conserving Higgs potential for which we present the allowed ranges of the input parameters and a statistical overview over the possible values of the Yukawa couplings.

    hep-phJHEP(2019)·8 citations
24. 24*

    Quarkonium production and TMDs at LHC

    U. D'Alesio🇮🇹 · F. Murgia🇮🇹 · C. Pisano🇮🇹 · S. Rajesh🇮🇹

    In this contribution we briefly discuss an ongoing phenomenological programme on quarkonium production in unpolarized and polarized proton-proton collisions in a fixed target setup at LHCb, the LHCSpin project. Within a TMD approach, we aim at considering in particular: the relative role of the NRQCD color-singlet and color-octet production mechanisms, both for unpolarized and polarized quarkonium production; the study of azimuthal and transverse single-spin asymmetries as a phenomenological tool for learning about the almost unknown gluon Sivers function; the role of initial- and final-state interactions for spin asymmetries.

    hep-phPoS(2019)·0 citations
25. 25*

    Connecting the Higgs Potential and Primordial Black Holes

    De-Chang Dai🇨🇳 · Ruth Gregory🇬🇧 · Dejan Stojkovic🇺🇸

    It was recently demonstrated that small small black holes can act as seeds for nucleating decay of the metastable Higgs vacuum, dramatically increasing the tunneling probability. Any primordial black hole lighter than $4.5\times 10^{14}$g at formation would have evaporated by now, and in the absence of new physics beyond the standard model, would therefore have entered the mass range in which seeded decay occurs, however, such true vacuum bubbles must percolate in order to completely destroy the false vacuum; this depends on the bubble number density and the rate of expansion of the universe. Here, we compute the fraction of the universe that has decayed to the true vacuum as a function of the formation temperature (or equivalently, mass) of the primordial black holes, and the spectral index of the fluctuations responsible for their formation. This allows us to constrain the mass spectrum of primordial black holes given a particular Higgs potential and conversely, should we discover primordial black holes of definite mass, we can constrain the Higgs potential parameters.

    hep-phastro-ph.COhep-thPRD(2020)·40 citations
26. 26*

    Higgs masses and couplings in the general 2HDM with unitarity bounds

    D. Jurčiukonis🇱🇹 · L. Lavoura🇵🇹

    We investigate the general two Higgs doublet model imposing both the unitarity conditions and the bounded-from-below conditions. Both types of conditions restrict the ranges of the parameters of the scalar potential. We study the model in the Higgs basis, i.e. in the basis for the scalar doublets where only one doublet has vacuum expectation value. We use the experimental bounds on the oblique parameter T, to produce scalar particles with masses and cubic and quartic couplings of the Higgs in agreement with the phenomenology. The numerical calculations show that the cubic coupling may be up to 1.6 times larger than in the Standard Model, but it may also be zero or even negative. The quartic coupling is always positive and may be up to four times larger than in the Standard Model.

    hep-phPoS(2019)·0 citations
27. 27*

    NNLO compatibility between pQCD theory and phenomenology in determination of the $b$-quark pole and \MSbar running masses

    A. Vafaee · K. Javidan · A. B. Shokouhi

    This contribution attempts to determine the $b$-quark pole mass $M_b$ and \MSbar running mass ${\overline{m}}_b$ with two different approaches at the next-to-next-to-leading order (NNLO) corrections. At the first approach, we derive a relation between the $b$-quark pole mass $M_b$ and its \MSbar running mass ${\overline{m}}_b$ at the NNLO corrections based on the perturbative Quantum Chromo Dynamics (pQCD) predictions. At the second approach, we extract numerical values of the $b$-quark pole and \MSbar running masses based on the NNLO phenomenology of H1 and ZEUS Collaborations combined beauty vertex production experimental data. Then we discuss about the compatibility between the pQCD theory results and phenomenology approach in determination of the $b$-quark pole and \MSbar running masses at the NNLO corrections. Also, we investigate the role and influence of the $b$-quark mass as an extra degree of freedom added to the input parameters of the Standard Model Lagrangian, on the improvement of the uncertainty band of the proton parton distribution functions (PDFs) and particularly on the gluon distribution.

    hep-phMod.Phys.Lett.A(2020)·1 citation
28. 28*

    Combinatorial aspects in the one-loop renormalization of higher derivative theories

    Christian F. Steinwachs🇩🇪

    An efficient way to calculate one-loop counterterms within the Feynman diagrammatic approach and dimensional regularization is to expand the propagators in the integrands of the Feynman integrals around vanishing external momentum. In this way, a generic one-loop diagram is reduced to a sum of vacuum diagrams. The logarithmically divergent part can be extracted by power counting arguments. In case of higher derivative theories, the standard implementation of this procedure on a computer algebra system can become quickly inefficient due to a high proliferation of terms coming from the intermediate replacement of high-rank tensor-integrals with symmetrized product of metric tensors. In this note we present a simple combinatorial solution to this problem which makes the implementation much more efficient. This method is especially relevant in the renormalization of higher derivative theories, but might as well be integrated as a standard routine in existing computer algebra programs designed to automatize Feynman diagrammatic calculations.

    hep-phgr-qchep-th4 citations
29. 29*

    A Toolbox for $q_T$ and $0$-Jettiness Subtractions at N${}^3$LO

    Georgios Billis🇩🇪 · Markus A. Ebert🇺🇸 · Johannes K. L. Michel🇩🇪 · Frank J. Tackmann🇩🇪

    We derive the leading-power singular terms at three loops for both $q_T$ and 0-jettiness, ${\mathcal{T}}_0$, for generic color-singlet processes. Our results provide the complete set of differential subtraction terms for $q_T$ and ${\mathcal{T}}_0$ subtractions at N${}^3$LO, which are an important ingredient for matching N${}^3$LO calculations with parton showers. We obtain the full three-loop structure of the relevant beam and soft functions, which are necessary ingredients for the resummation of $q_T$ and ${\mathcal{T}}_0$ at N${}^3$LL${}^{\prime }$ and N${}^4$LL order, and which constitute important building blocks in other contexts as well. The nonlogarithmic boundary coefficients of the beam functions, which contribute to the integrated subtraction terms, are not yet fully known at three loops. By exploiting consistency relations between different factorization limits, we derive results for the $q_T$ and ${\mathcal{T}}_0$ beam function coefficients at N${}^3$LO in the $z\to 1$ threshold limit, and we also estimate the size of the unknown terms beyond threshold.

    hep-phEur.Phys.J.Plus(2021)·78 citations
30. 30*

    Lattice investigation of an inhomogeneous phase of the 2+1-dimensional Gross-Neveu model in the limit of infinitely many flavors

    Marc Winstel🇩🇪 · Jonas Stoll🇩🇪 · Marc Wagner🇩🇪

    We investigate the phase structure of the 2+1-dimensional Gross-Neveu model in the large-Nf limit, where Nf denotes the number of fermion flavors. We discuss two different fermion representations and their implication on the interpretation of a discrete symmetry of the action. We present numerical results, which indicate the existence of an inhomogeneous phase similar as in the 1+1-dimensional Gross-Neveu model.

    ↳ hep-lathep-phJ.Phys.Conf.Ser.(2020)·16 citations
31. 31*

    The Shape of the Correlation Function

    Jakub Cimerman🇨🇿 · Boris Tomášik🇸🇰 · Christopher Plumberg🇸🇪

    The correlation function measured in ultrarelativistic nuclear collisions is non-Gaussian. By making use of models we discuss and assess how much various effects can influence its shape. In particular, we focus on the parametrisations expressed with the help of Lévy-stable distributions. We show that the Lévy index may deviate substantially from 2 due to non-critical effects such as non-spherical shape, resonance decays, event-by-event fluctuations and functional dependence on $Q_{inv}$ or similar.

    ↳ nucl-thhep-phnucl-exPhys.Part.Nucl.(2020)·6 citations
32. 32*

    Resonant magnetogenesis from axions

    Teerthal Patel🇯🇵 · Hiroyuki Tashiro🇯🇵 · Yuko Urakawa🇯🇵

    We investigate the generation of seed magnetic field through the Chern-Simons coupling between the U(1) gauge field and an axion field that commences to oscillate at various epoch, depending on the mass scale. We address axions which begin oscillation during inflation, reheating, and also the radiation dominated era after the thermalization of the Universe. We study the resonant generation mechanisms and highlight that a small oscillation time scale with respect to that of the cosmic expansion can lead to an efficient generation of (hyper) magnetic field via resonant generation, even for $\mathcal{O}(1)$ coupling. In addition, we demonstrate that the generated field can be helical due to the tachyonic amplification phase prior to the onset of oscillation. Furthermore, it is shown that the parametric resonance during reheating can generate a circularly polarized (hyper) magnetic field in a void region with the present amplitude $B_0=3\times 10^{-15}$Gauss and the coherent length ${\lambda }_0=0.3$pc without being plagued by the backreaction issue.

    ↳ astro-ph.COhep-phhep-thJCAP(2020)·36 citations
33. 33*

    Color transparency in $\bar{p}d\to {\pi }^{-}{\pi }^{0}p$ reaction

    A.B. Larionov🇩🇪 · M. Strikman🇺🇸

    We consider exclusive two-pion production in antiproton-deuteron interactions at the beam momenta around 10 GeV/c in the kinematics with large momentum transfer in the underlying hard process $\bar{p}n\to {\pi }^{-}{\pi }^0$. The calculations are performed taking into account the antiproton and pion soft rescattering on the spectator proton in the framework of the generalized eikonal approximation. We focus on the color transparency effect that is modeled by introducing the dependence of rescattering amplitudes on the relative position of the struck and spectator nucleons along the momentum of a fast particle. As a consequence of the interplay between the impulse approximation and rescattering amplitudes the nuclear transparency ratio reveals a pretty complicated behaviour as a function of the transverse momentum of the spectator proton and the relative azimuthal angle between the ${\pi }^{-}$-meson and the proton. Color transparency significantly suppresses rescattering amplitudes which leads to substantial modifications of the nuclear transparency ratio moving it closer to the value obtained in the impulse approximation. By performing the Monte-Carlo analysis we determine that this effect can be studied at PANDA with a reasonable statistics.

    ↳ nucl-thhep-exhep-phnucl-exEPJA(2020)·7 citations
34. 34*

    Nucleon axial, tensor and scalar charges and $\sigma$-terms in lattice QCD

    C. Alexandrou (Univ. of Cyprus & The Cyprus Inst.) · S. Bacchio (The Cyprus Inst.) · M. Constantinou (Temple Univ.) · K. Hadjiyiannakou (The Cyprus Inst.) · K. Jansen (DESY-Zeuthen) · G. Koutsou (The Cyprus Inst.) · A. Vaquero Aviles-Casco (Univ. of Utah)

    We determine the nucleon axial, scalar and tensor charges within lattice Quantum Chromodynamics including all contributions from valence and sea quarks. We analyze three gauge ensembles simulated within the twisted mass formulation at approximately physical value of the pion mass. Two of these ensembles are simulated with two dynamical light quarks and lattice spacing $a=0.094$~fm and the third with $a=0.08$~fm includes in addition the strange and charm quarks in the sea. After comparing the results among these three ensembles, we quote as final values our most accurate analysis using the latter ensemble. For the nucleon isovector axial charge we find $1.286(23)$ in agreement with the experimental value. We provide the flavor decomposition of the intrinsic spin $\frac{1}{2}\Delta {\Sigma }^q$ carried by quarks in the nucleon obtaining for the up, down, strange and charm quarks $\frac{1}{2}\Delta {\Sigma }^u=0.431(8)$, $\frac{1}{2}\Delta {\Sigma }^d=-0.212(8)$, $\frac{1}{2}\Delta {\Sigma }^s=-0.023(4)$ and $\frac{1}{2}\Delta {\Sigma }^c=-0.005(2)$, respectively. The corresponding values of the tensor and scalar charges for each quark flavor are also evaluated providing valuable input for experimental searches for beyond the standard model physics. In addition, we extract the nucleon $\sigma$-terms and find for the light quark content ${\sigma }_{\pi N}=41.6(3.8)$~MeV and for the strange ${\sigma }_s=45.6(6.2)$~MeV. The y-parameter that is used in phenomenological studies we find $y=0.078(7)$.

    ↳ hep-lathep-exhep-phnucl-ex+1PRD(2020)·158 citations
35. 35*

    Analytic self-gravitating $4$-Baryons, traversable NUT-AdS wormholes, flat space-time multi-Skyrmions at finite volume and a novel transition in the $SU(3)$-Skyrme model

    Eloy Ayón-Beato🇲🇽 · Fabrizio Canfora🇨🇱 · Marcela Lagos🇨🇱 · Julio Oliva🇨🇱 · Aldo Vera🇨🇱

    We construct the first analytic self-gravitating Skyrmions with higher Baryon charge in four dimensions for the $SU(3)$-Skyrme-Einstein-$\Lambda$ theory by combining the generalized hedgehog ansatz with the approach developed by Balachandran et al. to describe the first (numerical) example of a non-embedded solution. These are genuine $SU(3)$ analytic solutions instead of trivial embeddings of $SU(2)$ into $SU(3)$ and its geometry is that of a Bianchi IX Universe. The Skyrme ansatz is chosen in such a way that the Skyrme field equations are identically satisfied in the sector with Baryon charge 4. The field equations reduce to a dynamical system for the three Bianchi IX scale factors. Particular solutions are explicitly analyzed. Traversable wormholes with NUT-AdS asymptotics supported by a topologically non-trivial $SU(3)$-sigma soliton are also constructed. The self-gravitating solutions admit also a suitable flat limit giving rise to Skyrmions of charge 4 confined in a box of finite volume maintaining the integrability of the $SU(3)$ Skyrme field equations. This formalism discloses a novel transition at finite Baryon density arising from the competition between embedded and non-embedded solutions in which the non-embedded solutions prevail at high density while are suppressed at low densities.

    ↳ hep-thgr-qchep-phnucl-thEPJC(2020)·38 citations
36. 36*

    B-mode Power Spectrum of CMB via Polarized Compton Scattering

    Jafar Khodagholizadeh🇮🇷 · Rohoollah Mohammadi🇮🇷 · Mahdi Sadegh🇮🇷 · Ali Vahedi🇮🇷

    In this work, according to some evidence from being an asymmetry in the number density of left and right-handed electrons, ${\delta }_L$, in-universe motivate us to calculate the dominated contribution of this asymmetry in the generation of B-mode power spectrum $C_{Bl}^{(S)}$. Note, in the standard cosmological scenario, Compton scattering in the presence of scalar matter perturbation can not generate magnetic like pattern in linear polarization while in the case of polarized Compton scattering, we have shown $C_{Bl}^{(S)}\propto {\delta }_L^2$. We add up the spectrum of the B-mode generated by the polarized Compton scattering to the spectra produced by weak lensing effects and Compton scattering in the presence of tensor perturbations. The results show a significant amplification in $C_{Bl}$ in large scale $l<500$ for ${\delta }_L>10^{-6}$ which will be observable in future high resolution B-mode polarization detection. Finally, we have shown that $C_{Bl}^{(S)}$ generated by polarized Compton scattering can suppress the tensor to scalar ratio, $r$ parameter so that this contamination can be comparable to a primordial tensor-to-scalar ratio spatially for ${\delta }_L>10^{-5}$.

    ↳ astro-ph.COastro-ph.HEhep-phhep-thJCAP(2020)·5 citations
37. 37*

    Dark Matter Signals on a Laser Interferometer

    Satoshi Tsuchida🇯🇵 · Nobuyuki Kanda🇯🇵 · Yousuke Itoh🇯🇵 · Masaki Mori🇯🇵

    WIMPs are promising dark matter candidates. A WIMP occasionally collides with a mirror equipped with interferometric gravitational wave detectors such as LIGO, Virgo, KAGRA and the Einstein Telescope (ET). When WIMPs collide with a mirror of an interferometer, we expect that characteristic motions of the pendulum and mirror are excited, and those signals could be extracted by highly sophisticated sensors developed for gravitational wave detection. We analyze the motions of the pendulum and mirror, and estimate the detectability of these motions. For the "Thin-ET" detector, the signal-to-noise ratio may be $1.7\left(\frac{m_{\mathrm{DM}}}{100\mathrm{GeV}}\right)$, where $m_{\mathrm{DM}}$ is the mass of a WIMP. We may set a more strict upper limit on the cross section between a WIMP and a nucleon than the limits obtained by other experiments so far when $m_{\mathrm{DM}}$ is approximately lower than 0.2 GeV. We find an order-of-magnitude improvement in the upper limit around $m_{\mathrm{DM}}=0.2\mathrm{GeV}$.

    ↳ astro-ph.HEhep-phPRD(2020)·18 citations
38. 38*

    The role of the chemical potential in coupling superfluid dark matter to baryons

    Tobias Mistele🇩🇪

    Superfluid dark matter postulates that the centers of galaxies contain superfluid condensates. An important quantity regarding these superfluids is their chemical potential $\mu$. Here, we discuss two issues related to this chemical potential. First, there is no exactly conserved quantity associated with this chemical potential due to the symmetry-breaking baryon-phonon coupling. Second, $\mu$ is sometimes introduced by shifting the phonon field by $\mu \cdot t$ which -- again due to the symmetry-breaking baryon-phonon coupling -- introduces an explicit time dependence in the Lagrangian. We investigate under which conditions introducing a chemical potential is nevertheless justified and show how to correctly introduce it when these conditions are met. We further propose a model that recovers superfluid dark matter's zero-temperature equations of motion including a chemical potential even if the aforementioned conditions for justifying a chemical potential are not met.

    ↳ astro-ph.GAhep-phhep-thJCAP(2019)·8 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.