Fri·Jan 25, 2019Friday·January 25, 2019

1. 01*

   The Color Glass Condensate density matrix: Lindblad evolution, entanglement entropy and Wigner functional

   Nestor Armesto🇪🇸 · Fabio Dominguez🇪🇸 · Alex Kovner🇺🇸 · Michael Lublinsky🇮🇱 · Vladimir Skokov🇺🇸

   We introduce the notion of the Color Glass Condensate (CGC) density matrix $\hat{\rho }$. This generalizes the concept of probability density for the distribution of the color charges in the hadronic wave function and is consistent with understanding the CGC as an effective theory after integration of part of the hadronic degrees of freedom. We derive the evolution equations for the density matrix and show that the JIMWLK evolution equation arises here as the evolution of diagonal matrix elements of $\hat{\rho }$ in the color charge density basis. We analyze the behavior of this density matrix under high energy evolution and show that its purity decreases with energy. We show that the evolution equation for the density matrix has the celebrated Kossakowsky-Lindblad form describing the non-unitary evolution of the density matrix of an open system. Additionally, we consider the dilute limit and demonstrate that, at large rapidity, the entanglement entropy of the density matrix grows linearly with rapidity according to $d{S}_e/dy=\gamma$, where $\gamma$ is the leading BFKL eigenvalue. We also discuss the evolution of $\hat{\rho }$ in the saturated regime and relate it to the Levin-Tuchin law and find that the entropy again grows linearly with rapidity, but at a slower rate. By analyzing the dense and dilute regimes of the full density matrix we are able to establish a duality between the regimes. Finally we introduce the Wigner functional derived from this density matrix and discuss how it can be used to determine the distribution of color currents, which may be instrumental in understanding dynamical features of QCD at high energy.

   hep-phJHEP(2019)·74 citations
2. 02*

   Constraining Sterile Neutrino Interpretations of the LSND and MiniBooNE Anomalies with Coherent Neutrino Scattering Experiments

   Carlos Blanco🇺🇸 · Dan Hooper🇺🇸 · Pedro Machado🇺🇸

   Results from the LSND and MiniBooNE experiments have been interpreted as evidence for a sterile neutrino with a mass near the electronvolt scale. Here we propose to test such a scenario by measuring the coherent elastic scattering rate of neutrinos from a pulsed spallation source. Coherent scattering is universal across all active neutrino flavors, and thus can provide a measurement of the total Standard Model neutrino flux. By performing measurements over different baselines and making use of timing information, it is possible to significantly reduce the systematic uncertainties and to independently measure the fluxes of neutrinos that originate as ${\nu }_{\mu }$ or as either ${\nu }_e$ or ${\bar{\nu }}_{\mu }$. We find that a 100 kg CsI detector would be sensitive to the large fraction of the sterile neutrino parameter space that could potentially account for the LSND and MiniBooNE anomalies.

   hep-phPRD(2020)·63 citations
3. 03*

   Differential Dyson-Schwinger equations for quantum chromodynamics

   Marco Frasca🇮🇹

   Using a technique devised by Bender, Milton and Savage, we derive the Dyson-Schwinger equations for quantum chromodynamics in differential form. We stop our analysis to the two-point functions. The 't~Hooft limit of color number going to infinity is derived showing how these equations can be cast into a treatable even if approximate form. It is seen how this limit gives a sound description of the low-energy behavior of quantum chromodynamics by discussing the dynamical breaking of chiral symmetry and confinement, providing a condition for the latter. This approach exploits a background field technique in quantum field theory.

   hep-phEPJC(2020)·14 citations
4. 04*

   Baryogenesis from B Meson Oscillations

   Ann E. Nelson🇺🇸 · Huangyu Xiao🇺🇸

   We show how CP violating B meson oscillations in conjunction with baryon number violating decays can generate the cosmological asymmetry between matter and anti-matter, and explore the parameter space of a simple, self-contained model, which can be tested via exotic B meson decays, and via the charge asymmetry in semi-leptonic decays of neutral B mesons.

   hep-phPRD(2019)·47 citations
5. 05*

   Top-quark pair production at complete-NLO accuracy with NNLO+NNLL${}^{\prime }$ corrections in QCD

   Michal Czakon🇩🇪 · Andrea Ferroglia🇺🇸 · Alexander Mitov🇬🇧 · Davide Pagani🇩🇪 · Andrew S. Papanastasiou🇬🇧 · Benjamin D. Pecjak🇬🇧 · Darren J. Scott🇳🇱 · Ioannis Tsinikos🇩🇪 · Xing Wang🇨🇳 · Li Lin Yang🇨🇳 · Marco Zaro🇳🇱

   We describe predictions for top-quark pair differential distributions at hadron colliders, which combine state-of-the-art NNLO QCD calculations and NLO electroweak corrections together with double resummation at NNLL${}^{\prime }$ accuracy of threshold logarithms and small-mass logarithms. This is the first time that such a combination has appeared in the literature. Numerical results are presented for the invariant-mass distribution, the transverse-momentum distribution as well as rapidity distributions.

   hep-phhep-exCPC(2020)·31 citations
6. 06*

   Common explanation to the $R_{K^{(\ast )}}$, $R_{D^{(\ast )}}$ and ${ϵ}^{\prime }/ϵ$ anomalies in a 3HDM+${\nu }_R$ and connections to neutrino physics

   Carlo Marzo🇪🇪 · Luca Marzola🇪🇪 · Martti Raidal🇪🇪

   Scalar theories can account for the current $R_{D^{(\ast )}}$ measurements through a vector operator ${\bar{c}}_L{\gamma }_{\mu }{b}_L{\bar{\tau }}_L{\gamma }^{\mu }{\nu }_L$ induced at the loop level. Once the vector contribution is considered on top of a subdominant tree-level scalar component, the predicted value of $R_{D^{(\ast )}}$ falls within the $1\sigma$ region indicated by the experiments. We explicitly demonstrate this claim in the framework of a three Higgs doublet model extended with GeV scale right-handed neutrinos, by matching the anomalous signal for perturbative values of the involved couplings and respecting the bounds from complementary flavour physics measurements. Remarkably, we furthermore show that the proposed framework can be employed to simultaneously explain also the present $R_{K^{(\ast )}}$ measurement, as well as the deviation in ${ϵ}^{\prime }/ϵ$ currently being debated in the literature. These results are obtained by considering the contribution of relatively light right-handed neutrinos which are fundamental in mediating the processes behind the anomalous signals. In this way our findings reveal a new possible connection that links the flavour anomalies to the phenomenology of extended Higgs sector and neutrino physics.

   hep-phPRD(2019)·30 citations
7. 07*

   Production of the Madala boson in association with top quarks

   Stefan von Buddenbrock🇿🇦

   The Madala hypothesis is the prediction of a new heavy scalar, the Madala boson, that has had previous success in explaining several anomalies in LHC Run 1 and 2 data. In the literature, the Madala boson has so far primarily been discussed in the context of its dominant production mode, gluon fusion. However, it can be shown that a study of its production in association with top quarks can provide us with crucial information about the model, as well as explain the enhancement of top associates Higgs production that has been observed in the data -- most notably in leptonic channels. For this study, Monte Carlo events have been produced and passed through a detector simulation. These events are then run through an event selection designed by a CMS search for a single top quark in association with a Higgs boson. A fit is made to the CMS data, yielding a parameter constraint on the Madala hypothesis. With the Madala hypothesis prediction, an effective signal strength is calculated and compared with the observed values.

   hep-phThe Proceedings of SAIP2017, the 62nd Ann…·0 citations
8. 08*

   eV-scale Sterile Neutrinos

   C. Giunti🇮🇹 · T. Lasserre🇫🇷

   We address the phenomenology of light sterile neutrinos, with emphasis on short-baseline neutrino oscillations. After a review of the observed short-baseline neutrino oscillation anomalies, we discuss the global fit of the data and the current appearance-disappearance tension. We also review briefly the effects of light sterile neutrinos in $\beta$ decay, neutrinoless double-$\beta$ decay and cosmology. Finally, we discuss the future perspective in the search for the effects of eV-scale sterile neutrinos.

   hep-phAnn.Rev.Nucl.Part.Sci.(2019)·219 citations
9. 09*

   On lepton flavour universality in semileptonic $B_c\to {\eta }_c,J/\psi$ decays

   Domagoj Leljak🇭🇷 · Blazenka Melic🇭🇷 · Monalisa Patra🇸🇮

   We discuss $B_c\to {\eta }_c$ and $B_c\to J/\psi$ semileptonic decays within the Standard Model (SM) and beyond. The relevant transition form factors, being the main source of theoretical uncertainties, are calculated in the sum rule approach and are provided in a full $q^2$ range. We calculate the semileptonic branching fractions and find for the ratios, $R_{{\eta }_c}{|}_{\mathrm{SM}}=0.32\pm 0.02$, $R_{J/\psi }{|}_{\mathrm{SM}}=0.23\pm 0.01$. Both predictions are in agreement with other existing calculations and support the current tension in $R_{J/\psi }$ at 2$\sigma$ level with the experiment. To extend the potential of testing the SM in the semileptonic $B_c$ decays, we consider the forward-backward asymmetry and polarization observables. We also study the 4-fold differential distributions of $B_c\to J/\psi (J/\psi \to {\tilde{\ell }}^{-}{\tilde{\ell }}^{+}){\ell }^{-}{\bar{\nu }}_{\ell }$, where $\tilde{\ell }=e,\mu$, in the presence of different new physics scenarios and find that the new physics effects can significantly modify the angular observables and can also produce effects which do not exist in the SM. Using the constraints on the new physics couplings from the recent combined analysis of BaBar, Belle and LHCb data on semileptonic $B\to D^{(\ast )}$ decays, where the effects of new physics could be visible, we find that these different new physics scenarios are not able to simultaneously explain the current experimental value of $R_{J/\psi }$.

   hep-phJHEP(2019)·74 citations
10. 10*

    A short review on recent developments in TMD factorization and implementation

    Ignazio Scimemi🇪🇸

    In the latest years the theoretical and phenomenological advances in the factorization of several collider processes using the transverse momentum dependent distributions (TMD)has greatly increased. I attempt here a short resume of the newest developments discussing also the most recent perturbative QCD calculations. The work is not strictly directed to experts in the field and it wants to offer an overview of the tools and concepts which are behind the TMD factorization and evolution. I consider both theoretical and phenomenological aspects, some of which have still to be fully explored. It is expected that actual colliders and the Electron Ion Collider (EIC) will provide important information in this respect.

    hep-phhep-exhep-latnucl-thAdv.High Energy Phys.(2019)·20 citations
11. 11*

    Next-to-next-to-leading-order QCD corrections to $e^{+}{e}^{-}\to J/\psi +{\eta }_c$ at $B$ factories

    Feng Feng🇨🇳 · Yu Jia🇨🇳 · Zhewen Mo🇨🇳 · Wen-Long Sang🇨🇳 · Jia-Yue Zhang🇨🇳

    Within the nonrelativistic QCD (NRQCD) factorization framework, we compute the long-awaited $\mathcal{O}({\alpha }_s^2)$ correction for the exclusive double charmonium production process at $B$ factories, {\it i.e.}, $e^{+}{e}^{-}\to J/\psi +{\eta }_c$ at $\sqrt{s}=10.58$ GeV. For the first time, we confirm that NRQCD factorization does hold at next-to-next-to-leading-order (NNLO) for exclusive double charmonium production. It is found that including the NNLO QCD correction considerably reduces the renormalization scale dependence, and also implies the reasonable perturbative convergence behavior for this process. Our state-of-the-art prediction is consistent with the BaBar measurement within errors.

    hep-phhep-exPLB(2024)·38 citations
12. 12*

    The Tensor Pomeron and Low-x Deep Inelastic Scattering

    Daniel Britzger🇩🇪 · Carlo Ewerz🇩🇪 · Sasha Glazov🇩🇪 · Otto Nachtmann🇩🇪 · Stefan Schmitt🇩🇪

    The tensor-pomeron model is applied to low-x deep-inelastic lepton-nucleon scattering and photoproduction. We consider c.m. energies in the range 6 - 318 GeV and Q^2 < 50 GeV^2. In addition to the soft tensor pomeron, which has proven quite successful for the description of soft hadronic high-energy reactions, we include a hard tensor pomeron. We also include f_2-reggeon exchange which turns out to be particularly relevant for real-photon-proton scattering at c.m. energies in the range up to 30 GeV. The combination of these exchanges permits a description of the absorption cross sections of real and virtual photons on the proton in the same framework. In particular, a detailed comparison of this two-tensor-pomeron model with the latest HERA data for x < 0.01 is made. Our model gives a very good description of the transition from the small-Q^2 regime where the real or virtual photon behaves hadron-like to the large-Q^2 regime where hard scattering dominates. Our fit allows us, for instance, a determination of the intercepts of the hard pomeron as 1.3008(+73,-84), of the soft pomeron as 1.0935(+76,-64), and of the f_2 reggeon. We find that in photoproduction the hard pomeron does not contribute within the errors of the fit. We show that assuming a vector instead of a tensor character for the pomeron leads to the conclusion that it must decouple in real photoproduction.

    hep-phhep-exPRD(2019)·42 citations
13. 13*

    Magnetic Moment of Leptons

    Samina Masood🇺🇸 · Holly Mein🇺🇸

    We show that the magnetic moment of leptons is significantly modified in thermal background as compared to the corresponding vacuum value. We compare the magnetic moment of all different leptons near nucleosynthesis. It is shown that the significance of thermal corrections depends on the temperature of the universe and the respective lepton mass. In the early universe, particle mass was growing quadratically with temperature which affects the corresponding value of magnetic moment. Intrinsic magnetic moment is inversely proportional to mass whereas thermal corrections to the neutrino dipole moment is proportional to neutrino mass for the Dirac type neutrino in the minimal standard model. Therefore the effect of temperature is not the same for charged leptons and neutrinos.

    hep-ph1 citation
14. 14*

    Observable signatures of dark photons from supernovae

    William DeRocco🇺🇸 · Peter W. Graham🇺🇸 · Daniel Kasen🇺🇸 · Gustavo Marques-Tavares🇺🇸 · Surjeet Rajendran🇺🇸

    A dark photon is a well-motivated new particle which, as a component of an associated dark sector, could explain dark matter. One strong limit on dark photons arises from excessive cooling of supernovae. We point out that even at couplings where too few dark photons are produced in supernovae to violate the cooling bound, they can be observed directly through their decays. Supernovae produce dark photons which decay to positrons, giving a signal in the 511 keV annihilation line observed by SPI/INTEGRAL. Further, prompt gamma-ray emission by these decaying dark photons gives a signal for gamma-ray telescopes. Existing GRS observations of SN1987a already constrain this, and a future nearby SN could provide a detection. Finally, dark photon decays from extragalactic SN would produce a diffuse flux of gamma rays observable by detectors such as SMM and HEAO-1. Together these observations can probe dark photon couplings several orders of magnitude beyond current constraints for masses of roughly 1 - 100 MeV.

    hep-phastro-ph.HEJHEP(2019)·104 citations
15. 15*

    Two-loop Doubly Massive Four-Point Amplitude Involving a half-BPS and Konishi Operator

    Taushif Ahmed🇩🇪 · Prasanna K. Dhani🇮🇹

    The two-loop four-point amplitude of two massless SU(N) colored scalars and two color singlet operators with different virtuality described by a half-BPS and Konishi operators is calculated analytically in maximally supersymmetric Yang-Mills theory. We verify the ultraviolet behaviour of the unprotected composite operator and exponentiation of the infrared divergences with correct universal values of the anomalous dimensions in the modified dimensional reduction scheme. The amplitude is found to contain lower transcendental weight terms in addition to the highest ones and the latter has no similarity with similar amplitudes in QCD.

    ↳ hep-thhep-phJHEP(2019)·8 citations
16. 16*

    Summary of WG7 at CKM 2018: "Mixing and $CP$ violation in the $D$ system: $x_D$, $y_D$, $|q/p{|}_D$, ${\varphi }_D$, and direct $CP$ violation in $D$ decays"

    Vishal Bhardwaj🇮🇳 · Mirco Dorigo🇨🇭 · Fu-Sheng Yu🇨🇳

    The "10${}^{\mathrm{th}}$ International Workshop on the CKM Unitary Triangle" took place at the University of Heidelberg on September 17${}^{\mathrm{th}}$-21${}^{\mathrm{st}}$, 2018. In this write-up, we summarize the material discussed at the workshop by the Working Group 7, which focused on latest experimental results and theoretical developments in the study of mixing and $CP$ violation in the neutral $D$ system, and of $CP$ violation and decay properties of other charm mesons and baryons.

    ↳ hep-exhep-ph2 citations
17. 17*

    Hybrid Hadronization

    Rainer J. Fries🇺🇸 · Michael Kordell🇺🇸

    We discuss Hybrid Hadronization, a hadronization model which interpolates between string fragmentation in dilute parton systems and quark recombination in dense parton systems. We lay out the basic principles, discuss some details of the implementation, and show some prelimiary results. Hybrid Hadronization is realized as a software package which works with PYTHIA 8 and will be released publicly in the near future.

    ↳ nucl-thhep-phPoS(2019)·10 citations
18. 18*

    Anomaly matching in QCD thermal phase transition

    Kazuya Yonekura🇯🇵

    We study an 't Hooft anomaly of massless QCD at finite temperature. With the imaginary baryon chemical potential at the Roberge-Weiss point, there is a ${\mathbb{Z}}_2$ symmetry which can be used to define confinement. We show the existence of a mixed anomaly between the ${\mathbb{Z}}_2$ symmetry and the chiral symmetry, which gives a strong relation between confinement and chiral symmetry breaking. The anomaly is a parity anomaly in the QCD Lagrangian reduced to three dimensions. It is reproduced in the chiral Lagrangian by a topological term related to Skyrmion charge, matching the anomaly before and after QCD phase transition. The effect of the imaginary chemical potential is suppresssed in the large $N$ expansion, and we discuss implications of the 't~Hooft anomaly matching for the nature of QCD phase transition with and without the imaginary chemical potential. Arguments based on universality alone are disfavored, and a first order phase transition may be the simplest possibility if the large $N$ expansion is qualitatively good.

    ↳ hep-thhep-lathep-phJHEP(2019)·44 citations
19. 19*

    Strangeness Enhancement in p+p, p+Pb and Pb+Pb Collisions at LHC Energies

    Y. Kanakubo🇯🇵 · M. Okai🇯🇵 · Y. Tachibana🇺🇸 · T. Hirano🇯🇵

    We investigate whether the quark gluon plasma (QGP) is created in small colliding systems from analyses of various hadron yields and their ratios in proton-proton (p+p), proton-lead (p+Pb) and lead-lead (Pb+Pb) collisions at LHC energies. Recently, the ALICE Collaboration reports enhancement of yield ratio of multi-strange hadrons to charged pions as a function of multiplicity at mid-rapidity. Motivated by these results, we develop the dynamical core-corona initialization framework and find that our results describe tendencies of the ALICE data especially for multi-strange hadrons. These results indicate that the QGP is partly formed in high multiplicity events in small colliding systems.

    ↳ nucl-thhep-phnucl-exJPS Conf.Proc.(2019)·3 citations
20. 20*

    Review on Composite Higgs Models

    Oliver Witzel🇺🇸

    Composite Higgs Models explore the possibility that the Higgs boson is an excitation of a new strongly interacting sector giving rise to electro-weak symmetry breaking. After describing how this new sector can be embedded into the Standard Model of elementary particle physics meeting experimental constraints, I will review efforts by the community to explore the physics of the new strong interaction using methods of lattice field theory. Challenges in understanding the numerical results are discussed and an outlook is given on possible future directions allowing to confirm or reject the composite Higgs hypothesis.

    ↳ hep-lathep-phPoS(2019)·92 citations
21. 21*

    Performance of various event generators in describing multijet final states at the LHC

    Stefan von Buddenbrock🇿🇦

    At the Large Hadron Collider (LHC), the most abundant processes which take place in proton-proton collisions are the generation of multijet events. These final states rely heavily on phenomenological models and perturbative corrections which are not fully understood, and yet for many physics searches at the LHC, multijet processes are an important background to deal with. It is therefore imperative that the modelling of multijet processes is better understood and improved. For this reason, a study has been done with several state-of-the-art Monte Carlo event generators, and their predictions are tested against ATLAS data using the Rivet framework. The results display a mix of agreement and disagreement between the predictions and data, depending on which variables are studied. Several points for improvement on the modelling of multijet processes are stated and discussed.

    ↳ hep-exhep-phThe Proceedings of SAIP2017, the 62nd Ann…·0 citations
22. 22*

    Viscous dark matter and 21 cm cosmology

    Jitesh R. Bhatt🇮🇳 · Arvind Kumar Mishra🇮🇳 · Alekha C. Nayak🇮🇳

    The EDGES experiment has detected the global absorption signal of 21 cm line at $z\sim 17$ in cosmic dawn era and reported its amplitude larger than the standard cosmological prediction. One of the possible explanation requires that the baryons were much cooler than the standard scenario. This requires an interaction between the dark and baryonic sectors with some appropriate cross-section, $\hat{\sigma }$. In this work, we examine the role that dissipative effects of cosmic fluid might play in influencing the 21 cm signal. We show that the presence of viscous dissipation of dark matter can significantly affect the energy transfer between the baryonic and dark matter fluids. It is demonstrated that the inclusion of the dissipative mechanism in the dark sector, strongly modify the earlier constraints on dark matter mass and $\hat{\sigma }$ obtain from EDGES observation. Further, we argue that EDGES absorption signal can put an independent bound on dark matter viscosity which is many order of magnitude larger than the maximum viscosity allowed by the structure formation.

    ↳ astro-ph.COhep-phPRD(2019)·34 citations
23. 23*

    WIMPs and stellar-mass primordial black holes are incompatible

    Julian Adamek🇬🇧 · Christian T. Byrnes🇬🇧 · Mateja Gosenca🇳🇿 · Shaun Hotchkiss🇳🇿

    We recently showed that postulated ultracompact minihalos with a steep density profile do not form in realistic simulations with enhanced initial perturbations. In this paper we assume that a small fraction of the dark matter consists of primordial black holes (PBHs) and simulate the formation of structures around them. We find that in this scenario halos with steep density profiles do form, consistent with theoretical predictions. If the rest of the dark matter consists of weakly interacting massive particles (WIMPs), we also show that WIMPs in the dense innermost part of these halos would annihilate and produce a detectable gamma-ray signal. The non-detection of this signal implies that PBHs make up at most one billionth of the dark matter, provided that their mass is greater than one millionth of the mass of the Sun. Similarly, a detection of PBHs would imply that the remaining dark matter could not be WIMPs.

    ↳ astro-ph.COhep-phhep-thPRD(2019)·167 citations
24. 24*

    Scheme dependence of asymptotically free solutions

    Holger Gies🇩🇪 · René Sondenheimer🇩🇪 · Alessandro Ugolotti🇩🇪 · Luca Zambelli🇩🇪

    Recent studies have provided evidence for the existence of new asymptotically free trajectories in non-Abelian particle models without asymptotic symmetry in the high-energy limit. We extend these results to a general $\mathrm{SU}(N_{\mathrm{L}})\times \mathrm{SU}(N_{\mathrm{c}})$ Higgs-Yukawa model that includes the non-Abelian sector of the standard model, finding further confirmation for such scenarios for a wide class of regularizations that account for threshold behavior persisting to highest energies. We construct these asymptotically free trajectories within conventional $\overline{\text{MS}}$ schemes and systematic weak coupling expansions. The existence of these solutions is argued to be a scheme-independent phenomenon, as demonstrated for mass-dependent schemes based on general momentum-space infrared regularizations. A change of scheme induces a map of the theory's coupling space onto itself, which in the present case also translates into a reparametrization of the space of asymptotically free solutions.

    ↳ hep-thhep-phEPJC(2019)·16 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.