Tue·Mar 5, 2019Tuesday·March 5, 2019

1. 01*

   Constraints on Mediator Coupled to Heavy Quarks from LHC Data

   Manuel Drees🇩🇪 · Zhongyi Zhang🇩🇪

   We apply LHC data to constrain a simplified extension of the Standard Model containing a new spin-1 mediator $R$, which does not couple to first generation quarks, and a spinor dark matter particle $\chi$. We recast ATLAS and CMS searches for final states containing one or more jet(s) + missing $E_T$, with or without $b$ tags, as well as searches for di-jet resonances with $b$ or $t$ tagging. We find that LHC constraints on the axial vector couplings of the mediator are always stronger than the unitarity bound, which scales like $m_R/m_t$. If $R$ has a sizable invisible branching ratio, the strongest LHC bound on both vector couplings and axial vector coupling comes from a di-jet + missing $E_T$ search with or without double $b$ tag. These bounds are quite strong for $m_R<1$ TeV, even though we have switched off all couplings to valence quarks. Searches for a di-jet resonance with double $b$ tag lead to comparable bounds with the previous results even if $R\to \chi \bar{\chi }$ decays are allowed; these are the only sensitive LHC searches if the invisible branching ratio of $R$ is very small or zero.

   hep-phhep-exPLB(2019)·6 citations
2. 02*

   Matching for FCNC effects in the flavour-symmetric SMEFT

   Tobias Hurth🇩🇪 · Sophie Renner🇩🇪 · William Shepherd🇩🇪

   We calculate the complete tree and one-loop matching of the dimension 6 Standard Model Effective Field Theory (SMEFT) with unbroken $U(3{)}^5$ flavour symmetry to the operators of the Weak Effective Theory (WET) which are responsible for flavour changing neutral current effects among down-type quarks. We also explicitly calculate the effects of SMEFT corrections to input observables on the WET Wilson coefficients, a necessary step on the way to a well-defined, complete prediction. These results will enable high-precision flavour data to be incorporated into global fits of the SMEFT at high energies, where the flavour symmetry assumption is widespread.

   hep-phJHEP(2019)·51 citations
3. 03*

   Gluon bremsstrahlung in finite media beyond multiple soft scattering approximation

   Yacine Mehtar-Tani🇺🇸

   We revisit the calculation of the medium-induced gluon spectrum in a finite QCD and develop a new approach that goes beyond multiple soft scattering approximation. We show by expanding around the harmonic oscillator that the first two orders encompass the two known analytic limits: single hard and multiple soft scattering regimes, valid at high and low frequencies, respectively. Finally, we investigate the sensitivity of our results to the infrared and observe that for large media the spectrum is weakly dependent on the infrared medium scale.

   hep-phnucl-thJHEP(2019)·83 citations
4. 04*

   QCD analysis of structure functions in deep inelastic neutrino-nucleon scattering without using the orthogonal polynomials approach

   A. Ghaffari Tooran🇮🇷 · A. Khorramian🇮🇷 · H. Abdolmaleki🇮🇷

   A nonsinglet QCD analysis of neutrino-nucleon structure function is performed based on all the data for charged current neutrino-nucleon deep inelastic scattering (DIS) corresponds to NLO and NNLO approximations, with taking into account the nuclear and higher twist corrections. In this analysis, we extract $x{u}_v(x,Q^2)$ and $x{d}_v(x,Q^2)$ valence parton distribution functions (PDFs) in a wide range of $x$ and $Q^2$, and determine their parametrization with the correlated errors using the xFitter framework. Our results regarding valence-quark densities with their uncertainties are compared to the prediction extracted using other PDF sets from different groups. We determine ${\alpha }_s(M_Z^2)$= 0.1199 $\pm$ 0.0031 and 0.1185 $\pm$ 0.0023 with considering the nuclear and higher twist corrections at the NLO and NNLO, respectively, and perform a comparison with other reported results. The extracted results regarding valence-quark distributions and the value of ${\alpha }_s(M_Z^2)$ are in good agreement with available theoretical models.

   hep-phPRC(2019)·11 citations
5. 05*

   Lamb shift in hydrogen-like muonic atoms to test fractal extra dimensions

   Daniela Grandón🇨🇱 · Alfredo Vega🇨🇱

   From the comparison between the experimental and theoretical results for the energy difference between 2s1/2 and 2p1/2 states in hydrogen and hydrogen-like ions with different values of Z, we estimate bounds for the presence of an extra fractional dimension. These bounds are higher when we work with muonic hydrogen and muonic deuterium, which open the possibility that future measurements of the Lamb shift in muonic atoms with one electron and higher values of Z may show evidence of the extra dimension.

   hep-phphysics.atom-ph2 citations
6. 06*

   The tetraquark $K_1(1400)$ in the decays $\tau \to [\omega (782),\varphi (1020)]K^{-}{\nu }_{\tau }$

   M. K. Volkov🇷🇺 · Aleksey A. Pivovarov🇷🇺 · K. Nurlan🇷🇺

   In the extended Nambu--Jona-Lasinio model, the decay widths of the processes $\tau \to [\omega (782),\varphi (1020)]K^{-}{\nu }_{\tau }$ were calculated. The intermediate strange quark-antiquark mesons in both the ground and the first radially excited states were taken into account. The meson $K_1(1400)$, being a possible candidate for the role of the tetraquark meson, was also taken into account as an intermediate state. The result for the process $\tau \to \omega (782)K^{-}{\nu }_{\tau }$ is in satisfactory agreement with the experimental data. Simultaneously, the result for the decay $\tau \to \varphi (1020)K^{-}{\nu }_{\tau }$ is in agreement with the experimental data with precision $1.3\sigma$.

   hep-ph1 citation
7. 07*

   Impacts of the intrinsic charm content of the proton on the ${\Xi }_{cc}$ hadroproduction at a fixed target experiment at the LHC

   Gu Chen🇨🇳 · Xing-Gang Wu🇨🇳 · Shuai Xu🇨🇳

   In the present paper, we present detailed discussions on the hadronic production of ${\Xi }_{cc}$ at a fixed target experiment at the LHC (After@LHC). The charm quarks in hadron could be either extrinsic or intrinsic. By using the BHPS model as the intrinsic charm distribution function in proton, we observe that even if by setting the proportion of finding the intrinsic charm in a proton as $A_{\mathrm{in}}=1\%$, total cross sections for the $g+c$ and $c+c$ production mechanisms shall be enhanced by nearly two times. Thus the number of ${\Xi }_{cc}$ events to be generated at the After@LHC can be greatly enhanced. Since the total cross sections and differential distributions for the ${\Xi }_{cc}$ production at the After@LHC are sensitive to the value of $A_{\mathrm{in}}$, the After@LHC could be a good platform for testing the idea of intrinsic charm.

   hep-phPRD(2019)·14 citations
8. 08*

   Yang-Mills ghost propagator in linear covariant gauges

   Fabio Siringo🇮🇹

   From first principles, using a screened expansion, a simple one-loop analytical expression is provided for the ghost propagator of pure SU(3) Yang-Mills theory in a generic linear covariant gauge. At variance with the Landau gauge, the ghost dressing function is suppressed in the infrared and vanishes at $p=0$, as predicted by other approaches in the continuum. However, in the very limited range where lattice data are available no detectable deviation is found from the Landau gauge, thus reconciling some recent lattice data and previous continuum predictions.

   hep-phhep-lathep-thPRD(2019)·14 citations
9. 09*

   Group-theoretical origin of CP violation

   Mu-Chun Chen🇺🇸 · Michael Ratz🇺🇸

   This is a short review of the proposal that CP violation may be due to the fact that certain finite groups do not admit a physical CP transformation. This origin of CP violation is realized in explicit string compactifications exhibiting the Standard Model spectrum.

   hep-phhep-thLHEP(2019)·9 citations
10. 10*

    Fracture Functions in Different Kinematic Regions and Their Factorizations

    X.P. Chai🇨🇳 · K.B. Chen🇨🇳 · J.P. Ma🇨🇳 · X.B. Tong🇨🇳

    Fracture functions are parton distributions of an initial hadron in the presence of an almost collinear particle observed in the final state. They are important ingredients in QCD factorization for processes where a particle is produced diffractively. There are different fracture functions for a process in different kinematic regions. We take the production of a lepton pair combined with a diffractively produced particle in hadron collisions to discuss this. Those fracture functions can be factorized further if there are large energy scales involved. They can be factorized with twist-2 parton distribution functions and fragmentation functions. We perform one-loop calculations to illustrate the factorization in the case with the diffractively produced particle as a real photon. Evolution equations of different fracture functions are derived from our explicit calculations. They agree with expectations. These equations can be used for re-summations of large log terms in perturbative expansions.

    hep-phJHEP(2019)·14 citations
11. 11*

    Semileptonic $D_{(s)}\to A{\ell }^{+}\nu$ and nonleptonic $D\to K_1(1270,1400)\pi$ decays in LCSR

    S. Momeni🇮🇷 · R. Khosravi🇮🇷

    In this work, the transition form factors are calculated for the semileptonic $D_{(s)}\to A{\ell }^{+}\nu$ where $A=a_1,b_1,K_1(1270,1400)$, i.e., $D^{+}\to a_1^0(b_1^0,K_1^0){\ell }^{+}\nu$, $D^0\to a_1^{-}(b_1^{-}){\ell }^{+}\nu$, and $D_s^{+}\to K_1^0{\ell }^{+}\nu$ in the frame work of the light-cone QCD sum rules (LCSR) approach up to the twist-3 distribution amplitudes (DAs). Since the masses of these axial vector mesons are comparable to the charm quark mass, we keep out in our calculations all terms including $m_A/m_c$ in expansion of two--parton DAs. Branching ratio values are estimated for the semileptonic $D_{(s)}\to A\ell \nu$ and nonleptonic $D\to K_1(1270,1400)\pi$ decays. A comparison is also made between our results and predictions of other methods and the existing experimental values.

    hep-phJ.Phys.G(2019)·24 citations
12. 12*

    Hadronization from color interactions

    Guang-Lei Li🇨🇳 · Chun-Bin Yang🇨🇳

    A quark coalescence model is presented based on semi-relativistic molecular dynamics with color interactions among quarks taken into account and applied to $pp$ collisions to study the effects of this model. A phenomenological potential with two tunable parameters is introduced to describe the color interactions between quarks and antiquarks. The interactions drive the process of hadronization and finally make them form different color neutral clusters, which can be identified as hadrons based on some criteria. A Monte Carlo generator, PYTHIA is used to generate the quarks in the initial state of hadronization, and different values of tunable parameters are used to study their effects on the final state distributions and correlations. Baryon to meson ratios, transverse momentum spectra, pseudorapidity distributions and forward-backward multiplicity correlations of hadrons produced in the hadronization process from this model with different parameters are compared with those from PYTHIA.

    hep-phCPC(2019)·0 citations
13. 13*

    The inclusive production of charged pion pairs in proton-antiproton collisions

    A.I. Ahmadov🇦🇿 · C. Aydin🇹🇷 · O. Uzun🇹🇷

    In this study, we have considered the contribution of the higher-twist (HT) effects of the subprocesses to inclusive pion pair production cross section in the high energy proton-antiproton collisions by using various pion distribution amplitudes (DAs) within the frozen coupling constant approach and compared them with the leading-twist contributions. The feature of the HT effects may help the theoretical interpretation of the future PANDA experiment. The dependencies of the HT contribution on the transverse momentum $p_T$, the center of mass energy $\sqrt{s}$, and the variable $x_T$ are discussed numerically with special emphasis put on DAs. Moreover, the obtained analytical and numerical results for the differential cross section of the pion pair production are compared with the elastic backward scattering of the pion on the proton. We show that the main contribution to the inclusive cross section comes from the HT direct production process via gluon-gluon fusion. Also, it is strongly dependent on the pion DAs, momentum cut-off parameter $△p$ and $<q_T^2>$ which is the mean square of the intrinsic momentum of either initial parton.

    hep-phPRC(2019)·0 citations
14. 14*

    Multi-Higgs-Doublet Models and Singular Alignment

    Werner Rodejohann🇩🇪 · Ulises Saldaña-Salazar🇩🇪

    We consider a 4-Higgs-doublet model in which each Higgs doublet gives mass to one of the fermion sets $\{m_t\}$, $\{m_b,m_{\tau },m_c\}$, $\{m_{\mu },m_s\}$, and $\{m_d,m_u,m_e\}$. The sets have the feature that within each of them the masses are similar. Our model explains the mass hierarchies of the sets by hierarchies of the vacuum expectation values of the Higgs doublets associated to them. All Yukawa couplings are therefore of order one. Neutrino masses are generated by a type-I seesaw mechanism with PeV-scale singlet neutrinos. To avoid the appearance of tree-level flavor changing neutral currents, we assume that all Yukawa matrices are singularly aligned in flavor space. We mean by this that the Yukawa matrices are given as linear combinations of the rank $1$ matrices that appear in the singular value decomposition of the mass matrix. In general, singular alignment allows to avoid flavor changing neutral currents in models with multiple Higgs doublets.

    hep-phJHEP(2019)·38 citations
15. 15*

    Overview of Spin Physics at EIC

    Daniël Boer🇳🇱

    The possibilities to measure spin effects at a high-energy Electron-Ion Collider (EIC) are reviewed from a theory point of view. Various types of spin distributions and promising observables are discussed.

    hep-phhep-exPoS(2019)·3 citations
16. 16*

    Impact of leptonic unitarity and dark matter direct detection experiments on the NMSSM with inverse seesaw mechanism

    Junjie Cao🇨🇳 · Yangle He🇨🇳 · Yusi Pan🇨🇳 · Yuanfang Yue🇨🇳 · Haijing Zhou🇨🇳 · Pengxuan Zhu🇨🇳

    In the Next-to-Minimal Supersymmetric Standard Model with the inverse seesaw mechanism to generate neutrino masses, the lightest sneutrino may act as a feasible dark matter candidate in vast parameter space. In this case, the smallness of the leptonic unitarity violation and the recent XENON-1T experiment can limit the dark matter physics. In particular, they set upper bounds of the neutrino Yukawa couplings ${\lambda }_{\nu }$ and $Y_{\nu }$. We study such effects by encoding the constraints in a likelihood function and carrying out elaborated scans over the parameter space of the theory with the Nested Sampling algorithm. We show that these constraints are complementary to each other in limiting the theory, and in some cases, they are very strict. We also study the impact of the future LZ experiment on the theory.

    hep-phJHEP(2020)·14 citations
17. 17*

    Nonperturbative Ball-Chiu construction of the three-gluon vertex

    A. C. Aguilar🇧🇷 · M. N. Ferreira🇧🇷 · C. T. Figueiredo🇧🇷 · J. Papavassiliou🇪🇸

    We present the detailed derivation of the longitudinal part of the three-gluon vertex from the Slavnov-Taylor identities that it satisfies, by means of a nonperturbative implementation of the Ball-Chiu construction; the latter, in its original form, involves the inverse gluon propagator, the ghost dressing function, and certain form factors of the ghost-gluon kernel. The main conceptual subtlety that renders this endeavor nontrivial is the infrared finiteness of the gluon propagator, and the resulting need to separate the vertex into two pieces, one that is intimately connected with the emergence of a gluonic mass scale, and one that satisfies the original set of Slavnov-Taylor identities, but with the inverse gluon propagator replaced by its "kinetic" term. The longitudinal form factors obtained by this construction are presented for arbitrary Euclidean momenta, as well as special kinematic configurations, parametrized by a single momentum. A particularly preeminent feature of the components comprising the tree-level vertex is their considerable suppression for momenta below 1 GeV, and the appearance of the characteristic "zero-crossing" in the vicinity of 100-200 MeV. Special combinations of the form factors derived with this method are compared with the results of recent large-volume lattice simulations as well as Schwinger-Dyson equations, and good overall agreement is found. A variety of issues related to the distribution of the pole terms responsible for the gluon mass generation are discussed in detail, and their impact on the structure of the transverse parts is elucidated. In addition, a brief account of several theoretical and phenomenological possibilities involving these newly acquired results is presented.

    hep-phhep-lathep-thPRD(2019)·48 citations
18. 18*

    Charged-lepton-flavor violation in $|\Delta S|=1$ hyperon decays

    Xiao-Gang He🇹🇼 · Jusak Tandean🇹🇼 · German Valencia🇦🇺

    Studies of lepton-flavor violation in strangeness-changing ($|\Delta S|=1$) transitions have a~long tradition in the kaon sector where they provide some of the strongest limits on physics beyond the standard model. Recent hints of violation of lepton-flavor universality in $B$-meson decays have revived interest in lepton-flavor violation as the two phenomena appear simultaneously in many extensions of the standard model. At the same time, the LHCb experiment has produced new results for the hyperon process ${\Sigma }^{+}\to p{\mu }^{+}{\mu }^{-}$ and may be in a position to study other rare hyperon decay modes. With this in mind, we investigate $|\Delta S|=1$ hyperon decays into different-flavor lepton pairs $e^{\pm }{\mu }^{\mp }$ in a model-independent manner and contrast the coverage of parameter space that can be achieved with what is known from kaon modes. We include a comparison with selected two-body leptonic decays of charged mesons, with $K\to \pi \nu \bar{\nu }$ modes, with $\mu \to e$ conversion, and with lepton-flavor violating decays of other neutral mesons, all of which constrain the same parameter space in a complementary~way.

    hep-phhep-exnucl-thJHEP(2019)·10 citations
19. 19*

    Triangle singularity in the $J/\psi \to K^{+}{K}^{-}{f}_0(980)(a_0(980))$ decays

    Wei-Hong Liang🇨🇳 · Hua-Xing Chen🇨🇳 · Eulogio Oset🇪🇸 · En Wang🇨🇳

    We study the $J/\psi \to K^{+}{K}^{-}{f}_0(980)(a_0(980))$ reaction and find that the mechanism to produce this decay develops a triangle singularity around $M_{\mathrm{inv}}(K^{-}{f}_0/K^{-}{a}_0)\approx 1515$~MeV. The differential width $d\Gamma /d{M}_{\mathrm{inv}}(K^{-}{f}_0/K^{-}{a}_0)$ shows a rapid growth around the invariant mass being 1515~MeV as a consequence of the triangle singularity of this mechanism, which is directly tied to the nature of the $f_0(980)$ and $a_0(980)$ as dynamically generated resonances from the interaction of pseudoscalar mesons. The branching ratios obtained for the $J/\psi \to K^{+}{K}^{-}{f}_0(980)(a_0(980))$ decays are of the order of $10^{-5}$, accessible in present facilities, and we argue that their observation should provide relevant information concerning the nature of the low-lying scalar mesons.

    hep-phhep-exEPJC(2019)·38 citations
20. 20*

    Higher-order corrections to jet quenching

    Yacine Mehtar-Tani🇺🇸 · Konrad Tywoniuk🇳🇴

    We compute the inclusive jet spectrum in the presence of a dense QCD medium by going beyond the single parton energy loss approximation. We show that higher-order corrections are important yielding large logarithmic contributions that must be resummed to all orders. This reflects the fact that jet quenching is sensitive to fluctuations of the jet substructure.

    hep-phnucl-thPoS(2019)·1 citation
21. 21*

    Broadening and saturation effects in dijet azimuthal correlations in p-p and p-Pb collisions at $\sqrt{{\mathbf{s}}_{\mathbf{NN}}}=$ 5.02 TeV

    Andreas van Hameren🇵🇱 · Piotr Kotko🇵🇱 · Krzysztof Kutak🇵🇱 · Sebastian Sapeta🇵🇱

    We demonstrate that the recent forward-forward dijet correlation data measured by the ATLAS collaboration for proton-proton and proton-lead collisions are consistent with the broadening effects due to both the gluon saturation and the resummation of large logarithms of the hard scale (the so-called Sudakov logarithms). We find that both effects are necessary to describe the experimental results.

    hep-phPLB(2019)·53 citations
22. 22*

    Doubly-charged Higgs Boson at Future Electron-Proton Collider

    P. S. Bhupal Dev🇺🇸 · Sarif Khan🇮🇳 · Manimala Mitra🇮🇳 · Santosh Kumar Rai🇮🇳

    We explore the discovery prospect of the doubly-charged component of an $SU(2{)}_L$-triplet scalar at the future $e^{-}p$ collider FCC-eh, proposed to operate with an electron beam energy of 60 GeV and a proton beam energy of 50 TeV. We consider the associated production of the doubly-charged Higgs boson along with leptons and jet(s), and its subsequent prompt decay to same-sign lepton pair. This occurs for $\mathcal{O}(1)$ Yukawa coupling of the scalar triplet with charged leptons, which is expected for reasonably small vacuum expectation values of the neutral component of the triplet field that governs the neutrino mass generation in the type-II seesaw. We present our analysis for two different final states, $3l+\ge 1j$ and an inclusive $\ge 2l+\ge 1j$ channel. Considering its decay to electrons only, we find that the doubly-charged Higgs with mass around a TeV could be observed at $3\sigma$ confidence level with $\mathcal{O}(200){\mathrm{fb}}^{-1}$ of integrated luminosity, while masses up to 2 TeV could be probed within a few years of data accumulation. The signal proposed here becomes essentially background-free, if it is triggered in the $\mu \mu$ mode and a $5\sigma$ discovery is achievable in this channel for a TeV-scale doubly-charged Higgs with an integrated luminosity as low as $\mathcal{O}(50){\mathrm{fb}}^{-1}$. We also highlight the sensitivity of FCC-eh to the Yukawa coupling responsible for production of the doubly-charged Higgs boson as a function of its mass in both the $ee$ and $\mu \mu$ channels.

    hep-phhep-exPRD(2019)·25 citations
23. 23*

    The doubly virtual $({\pi }^0,\eta ,{\eta }^{\prime })\to {\gamma }^{\ast }{\gamma }^{\ast }$ transition form factors in the light-front quark model

    Ho-Meoyng Choi🇰🇷 · Hui-Young Ryu🇰🇷 · Chueng-Ryong Ji🇺🇸

    We report our investigation on the doubly virtual TFFs $F_{\mathrm{P}{\gamma }^{\ast }}(Q_1^2,Q_2^2)$ for the $\mathrm{P}\to {\gamma }^{\ast }(q_1){\gamma }^{\ast }(q_2)(\mathrm{P}={\pi }^0,\eta ,{\eta }^{\prime })$ transitions using the light-front quark model (LFQM). Performing a LF calculation in the exactly solvable manifestly covariant Bethe-Salpeter (BS) model as the first illustration, we used $q_1^{+}=0$ frame and found that both LF and manifestly covariant calculations produce exactly the same results for $F_{\mathrm{P}{\gamma }^{\ast }}(Q_1^2,Q_2^2)$. This confirms the absence of the LF zero mode in the doubly virtual TFFs. We then mapped this covariant BS model to the standard LFQM using the more phenomenologically accessible Gaussian wave function provided by the LFQM analysis of meson mass spectra. For the numerical analyses of $F_{\mathrm{P}{\gamma }^{\ast }}(Q_1^2,Q_2^2)$, we compared our LFQM results with the available experimental data and the perturbative QCD (pQCD) and the vector meson dominance (VMD) model predictions. As $(Q_1^2,Q_2^2)\to \infty$, our LFQM result for doubly virtual TFF is consistent with the pQCD prediction, i.e. $F_{\mathrm{P}{\gamma }^{\ast }}(Q_1^2,Q_2^2)\sim 1/(Q_1^2+Q_2^2)$, while it differs far from the result of VMD model which behaves $F_{\mathrm{P}{\gamma }^{\ast }}^{\mathrm{VMD}}(Q_1^2,Q_2^2)\sim 1/(Q_1^2{Q}_2^2)$. Our LFQM prediction for $F_{{\eta }^{\prime }{\gamma }^{\ast }}(Q_1^2,Q_2^2)$ shows an agreement with the very recent experimental data obtained from the BaBar collaboration for the ranges of $2<Q_1^2,Q_1^2<60$ GeV${}^2$.

    hep-phnucl-thPRD(2019)·9 citations
24. 24*

    New Weinberg operator for neutrino mass and its seesaw origin

    Josu Hernandez-Garcia🇮🇹 · Stephen F. King🇬🇧

    We consider a new Weinberg operator for neutrino mass of the form $H_u\widetilde{H_d}{L}_i{L}_j$ involving two different Higgs doublets $H_u,H_d$ with opposite hypercharge, where $\widetilde{H_d}$ is the charge conjugated doublet. It may arise from a model where the two Higgs doublets carry the same charge under a $U(1{)}^{\prime }$ gauge group which forbids the usual Weinberg operator but allows the mixed one. The new Weinberg operator may be generated via two right-handed neutrinos oppositely charged under the $U(1{)}^{\prime }$, which may be identified as components of a fourth vector-like family in a complete model. Such a version of the type I seesaw model, which we refer to as type Ib to distinguish it from the usual type Ia seesaw mechanism which yields the usual Weinberg operator, allows the possibility of having potentially large violations of unitarity of the leptonic mixing matrix whose bounds we explore. We also consider the relaxation of the unitarity bounds due to the further addition of a single right-handed neutrino, neutral under $U(1{)}^{\prime }$, yielding a usual type Ia seesaw contribution.

    hep-phJHEP(2019)·26 citations
25. 25*

    The role of residual symmetries in dark matter stability and the neutrino nature

    Cesar Bonilla🇩🇪 · Eduardo Peinado🇲🇽 · Rahul Srivastava🇪🇸

    We consider the class of models where Dirac neutrino masses at one loop and the dark matter stability can be obtained using only the global $U(1{)}_{B-L}$ symmetry already present in Standard Model. We discuss how the residual ${\mathcal{Z}}_n$ subgroup, left unbroken after the breaking of $U(1{)}_{B-L}$, dictates the neutrino nature, namely if they are Dirac or Majorana particles, as well as determines the stability of the dark matter candidate in such models. In particular, we show that without the correct breaking of $U(1{)}_{B-L}$ to an appropriate residual ${\mathcal{Z}}_n$ symmetry, the Dirac nature of neutrinos and/or dark matter stability might be lost. For completeness we also provide some examples where the dark matter stability is accidental or lost completely. Finally, we discuss one example model where the Dirac neutrinos with naturally small one loop masses as well as dark matter stability, are both protected by the same residual ${\mathcal{Z}}_6$ subgroup, without need for adding any new explicit or accidental symmetries beyond the Standard Model symmetries.

    hep-phastro-ph.COLHEP(2019)·26 citations
26. 26*

    Measurements of the top-quark mass in fixed schemes and with alternative methods using the ATLAS and CMS detectors at the LHC

    Teresa Barillari🇩🇪

    Selected topics of the top-quark mass measurements in well-defined schemes are presented. The measurements have been performed using data recorded with the ATLAS and CMS detectors at the LHC at proton-proton centre-of-mass energies of 7 and 8 TeV. Precision theoretical QCD calculations for both inclusive top-antitop quark pair production and top-antitop quark pair production with an additional jet to extract the top quark mass in the pole-mass scheme have been used.

    ↳ hep-exhep-ph0 citations
27. 27*

    Gaussian Processes, Median Statistics, Milky Way Rotation Curves

    Hai Yu🇺🇸 · Aman Singal🇺🇸 · Jacob Peyton🇺🇸 · Sara Crandall🇺🇸 · Bharat Ratra🇺🇸

    We use the Iocco et al. (2015) compilation of 2,780 circular velocity measurements to analyze the Milky Way rotation curve. We find that the error bars for individual measurements are non-gaussian, and hence instead derive median statistics binned central circular velocity values and error bars from these data. We use these median statistics central values and error bars to fit the data to simple, few parameter, rotation curve functions. These simple functions are unable to adequately capture the significant small scale spatial structure in these data and so provide poor fits. We introduce and use the Gaussian Processes (GP) method to capture this small scale structure and use it to derive Milky Way rotation curves from the binned median statistics circular velocity data. The GP method rotation curves have significant small-scale spatial structure superimposed on a broad rise to galactocentric radius $R\approx 7$ kpc and a decline at larger $R$. We use the GP method median statistics rotation curve to measure the Oort $A$ and $B$ constants and other characteristic rotation curve quantities. We study correlations in the residual circular velocities (relative to the GP method rotation curve). Along with other evidence for azimuthal asymmetry of the Milky Way circular rotation velocity field, we find that larger residual circular velocities seem to favor parts of spiral arms.

    ↳ astro-ph.GAastro-ph.COgr-qchep-phAstrophys.Space Sci.(2020)·5 citations
28. 28*

    Chiral transport in strong fields from holography

    Yanyan Bu🇨🇳 · Tuna Demircik🇮🇱 · Michael Lublinsky🇮🇱

    Anomaly-induced transport phenomena in presence of strong external electromagnetic fields are explored within a 4D field theory defined holographically as $U(1{)}_V\times U(1{)}_A$ Maxwell-Chern-Simons theory in Schwarzschild-$Ad{S}_5$. Two complementary studies are reported. In the first one, we present results on the Ohmic conductivity, diffusion constant, chiral magnetic conductivity, and additional anomaly-induced transport coefficients as functions of external e/m fields. Next, gradient resummation in a constant background magnetic field is performed. All-order resummed constitutive relations are parameterised by four momenta-dependent transport coefficient functions (TCFs). A highlight of this part is a thorough study of {\it non-dissipative} chiral magnetic waves (CMW) in strong magnetic fields.

    ↳ hep-thhep-phnucl-thJHEP(2019)·12 citations
29. 29*

    The Initial Spin Probability Distribution of Primordial Black Holes

    V. De Luca🇨🇭 · V. Desjacques🇮🇱 · G. Franciolini🇨🇭 · A. Malhotra🇨🇭 · A. Riotto🇨🇭

    We study the spin of primordial black holes produced by the collapse of large inhomogeneities in the early universe. Since such primordial black holes originate from peaks, that is, from maxima of the local overdensity, we resort to peak theory to obtain the probability distribution of the spin at formation. We show that the spin is a first-order effect in perturbation theory: it results from the action of first-order tidal gravitational fields generating first-order torques upon horizon-crossing, and from the asphericity of the collapsing object. Assuming an ellipsoidal shape, the typical value of the dimensionless parameter $a_{\mathrm{s}}=S/G_N{M}^2$, where $S$ is the spin and $M$ is the mass of the primordial black hole, is about ${\sigma }_{\delta }\sqrt{1-{\gamma }^2}/2\pi$. Here, ${\sigma }_{\delta }^2$ is the variance of the overdensity at horizon crossing and the parameter $\gamma$ is a measure of the width of the power spectrum giving rise to primordial black holes. One has $\gamma =1$ for monochromatic spectra. For these narrow spectra, the suppression arises because the velocity shear, which is strongly correlated with the inertia tensor, tends to align with the principal axis frame of the collapsing object. Typical values of $a_{\mathrm{s}}$ are at the percent level.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2019)·203 citations
30. 30*

    Dark compact objects: an extensive overview

    Maksym Deliyergiyev🇵🇱 · Antonino Del Popolo🇮🇹 · Laura Tolos🇩🇪 · Morgan Le Delliou🇨🇳 · Xiguo Lee🇨🇳 · Fiorella Burgio🇮🇹

    We study the structure of compact objects that contain non-self annihilating, self-interacting dark matter admixed with ordinary matter made of neutron star and white dwarf materials. We extend the previous work Phys. Rev. D 92 123002 (2015) on these dark compact objects by analyzing the effect of weak and strongly interacting dark matter with particle masses in the range of 1-500 GeV, so as to set some constraints in the strength of the interaction and the mass of the dark matter particle. We find that the total mass of the compact objects increases with decreasing dark matter particle mass. In the strong interacting case and for dark matter particle masses in the range 1-10 GeV, the total mass of the compact objects largely exceeds the $2M_{\odot }$ constraint for neutron star masses and the nominal $1M_{\odot }$for white dwarfs, while for larger dark matter particle masses or in the weakly interacting case the compact objects show masses in agreement or smaller than these constraints, thus hinting at the exclusion of strongly self-interacting dark matter of masses 1-10 GeV in the interior of these compact objects. Moreover, we observe that the smaller the dark matter particle mass, the larger the quantity of dark matter captured is, putting constraints on the dark matter mass trapped in the compact objects so as to fullfill $\simeq 2M_{\odot }$ observations. Finally, the inhomogeneity of distribution of dark matter in the Galaxy implies a mass dependence of compact objects from the environment which can be used to put constraints on the characteristics of the Galaxy halo DM profile and on particle mass. In view of the these results, we discuss the formation of the dark compact objects in an homogeneous and non-homogeneous dark matter environment.

    ↳ gr-qcastro-ph.HEhep-phnucl-thPRD(2019)·94 citations
31. 31*

    Reply to "Comment on "How (not) to renormalize integral equations with singular potentials in effective field theory"

    E. Epelbaum🇩🇪 · A. M. Gasparyan🇷🇺 · J. Gegelia🇩🇪 · Ulf-G. Meißner🇩🇪

    We offer a brief response to the criticism put forward by Pavon Valderrama about our recent paper on "How (not) to renormalize integral equations with singular potentials in effective field theory".

    ↳ nucl-thhep-phhep-thEPJA(2019)·14 citations
32. 32*

    Masses and electric charges: gauge anomalies and anomalous thresholds

    Cesar Gomez🇪🇸 · Raoul Letschka🇪🇸

    We work out in the forward limit and up to order $e^6$ in perturbation theory the collinear divergences. In this kinematical regime we discover new collinear divergences that we argue can be only cancelled using quantum interference with processes contributing to the gauge anomaly. This rules out the possibility of a quantum consistent and anomaly free theory with massless charges and long range interactions. We use the anomalous threshold singularities to derive a gravitational lower bound on the mass of the lightest charged fermion.

    ↳ hep-thhep-phEPJC(2020)·4 citations
33. 33*

    Gluon Radiation from a Classical Point Particle

    Keijo Kajantie🇫🇮 · Larry D. McLerran🇺🇸 · Risto Paatelainen🇨🇭

    We consider an initially at rest colored particle which is struck by an ultra-relativistic nucleus. The particle is treated classically both with respect to its motion and its color charge. The nucleus is treated as a sheet of colored glass within the context of the Color Glass Condensate framework. We compute both the momentum and coordinates of the struck classical particle and the emitted radiation. Our computations generalize the classic electrodynamics computation of the radiation of an accelerated charged particle to include the radiation induced by the charged gluon field. This latter contribution adds to the classic electrodynamics result and produces a gluon rapidity distribution that is roughly constant as a function of rapidity at rapidities far from the fragmentation region of the struck particles. These computations may form the basis of a first principles treatment for the initial conditions for the evolution of matter produced in the fragmentation region of asymptotically high energy collisions.

    ↳ nucl-thhep-phPRD(2019)·9 citations
34. 34*

    Constraints on mediator-based dark matter and scalar dark energy models using $\sqrt{s}=13$ TeV $pp$ collision data collected by the ATLAS detector

    ATLAS Collaboration

    Constraints on selected mediator-based dark matter models and a scalar dark energy model using up to $37{\mathrm{fb}}^{-1}$ $\sqrt{s}=13$ TeV $pp$ collision data collected by the ATLAS detector at the LHC during 2015-2016 are summarised in this paper. The results of experimental searches in a variety of final states are interpreted in terms of a set of spin-1 and spin-0 single-mediator dark matter simplified models and a second set of models involving an extended Higgs sector plus an additional vector or pseudo-scalar mediator. The searches considered in this paper constrain spin-1 leptophobic and leptophilic mediators, spin-0 colour-neutral and colour-charged mediators and vector or pseudo-scalar mediators embedded in extended Higgs sector models. In this case, also $\sqrt{s}=8$ TeV $pp$ collision data are used for the interpretation of the results. The results are also interpreted for the first time in terms of light scalar particles that could contribute to the accelerating expansion of the universe (dark energy).

    ↳ hep-exhep-phJHEP(2019)·190 citations
35. 35*

    Scrutinizing the evidence for dark matter in cosmic-ray antiprotons

    Alessandro Cuoco🇩🇪 · Jan Heisig🇧🇪 · Lukas Klamt🇩🇪 · Michael Korsmeier🇩🇪 · Michael Krämer🇩🇪

    Global fits of primary and secondary cosmic-ray (CR) fluxes measured by AMS-02 have great potential to study CR propagation models and search for exotic sources of antimatter such as annihilating dark matter (DM). Previous studies of AMS-02 antiprotons revealed a possible hint for a DM signal which, however, could be affected by systematic uncertainties. To test the robustness of such a DM signal, in this work we systematically study two important sources of uncertainties: the antiproton production cross sections needed to calculate the source spectra of secondary antiprotons and the potential correlations in the experimental data, so far not provided by the AMS-02 Collaboration. To investigate the impact of cross-section uncertainties we perform global fits of CR spectra including a covariance matrix determined from nuclear cross-section measurements. As an alternative approach, we perform a joint fit to both the CR and cross-section data. The two methods agree and show that cross-section uncertainties have a small effect on the CR fits and on the significance of a potential DM signal, which we find to be at the level of $3\sigma$. Correlations in the data can have a much larger impact. To illustrate this effect, we determine possible benchmark models for the correlations in a data-driven method. The inclusion of correlations strongly improves the constraints on the propagation model and, furthermore, enhances the significance of the DM signal up to above $5\sigma$. Our analysis demonstrates the importance of providing the covariance of the experimental data, which is needed to fully exploit their potential.

    ↳ astro-ph.HEhep-phPRD(2019)·125 citations
36. 36*

    Application of the path optimization method to the sign problem in an effective model of QCD with a repulsive vector-type interaction

    Kouji Kashiwa🇯🇵 · Yuto Mori🇯🇵 · Akira Ohnishi🇯🇵

    The path optimization method is applied to a QCD effective model with the Polyakov loop and the repulsive vector-type interaction at finite temperature and density to circumvent the model sign problem. We show how the path optimization method can increase the average phase factor and control the model sign problem. This is the first study which correctly treats the repulsive vector-type interaction in the QCD effective model with the Polyakov-loop via the Markov-chain Monte-Carlo approach. It is shown that the complexification of the temporal component of the gluon field and also the vector-type auxiliary field are necessary to evade the model sign problem within the standard path-integral formulation.

    ↳ hep-lathep-phhep-thPRD(2019)·31 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.