Fri·Mar 8, 2019Friday·March 8, 2019

1. 01*

   Parton distribution functions and constraints on the intrinsic charm content of the proton using BHPS approach

   H. Abdolmaleki🇮🇷 · A. Khorramian🇮🇷

   In this work, a new set of parton distribution functions taking into account the intrinsic charm (IC) contribution is presented. We focus on the impact of the EMC measurements on the large $x$ charm structure function as the strongest evidence for the intrinsic charm when combined with the HERA, SLAC and BCDMS data. The main goal of this paper is the simultaneous determination of the intrinsic charm probability $P_{c\bar{c}/p}$ and strong coupling ${\alpha }_s$. This allows us to study the interaction of these two quantities as well as the influence on the PDFs in the presence of IC contributions. By considering ${\alpha }_s$ which can be fix or free parameter from our QCD analysis, we find that although there is not a significant change in the extracted central value of PDFs and their uncertainties, the obtained value of $P_{c\bar{c}/p}$ change by factor 7.8\%. The extracted value of $P_{c\bar{c}/p}$ in the present QCD analysis is consistent with the recent reported upper limit of $1.93\%$, which is obtained for the first time from LHC measurements. We show the intrinsic charm probability is sensitive to the strong coupling constant and also the charm mass. The extracted value of the strong coupling constant ${\alpha }_s(M_Z^2)=0.1191\pm 0.0008$ at NLO is in good agreement with world average value and available theoretical models.

   hep-phPRD(2019)·13 citations
2. 02*

   Photon radiation in hot nuclear matter by means of chiral anomalies

   Kirill Tuchin🇺🇸

   A new mechanism of photon emission in the quark-gluon plasma is proposed. Photon dispersion relation in the presence of the $CP$-odd topological regions generated by the chiral anomaly acquires an imaginary mass. It allows photon radiation through the decay $q\to q\gamma$ and annihilation $q\bar{q}\to \gamma$ processes closely related to the chiral Cherenkov radiation. Unlike previous proposals this mechanism does not require an external magnetic field. The differential photon emission rate per unit volume is computed and shown to be comparable to the rate of photon emission in conventional processes.

   hep-phnucl-thPRC(2019)·9 citations
3. 03*

   Semileptonic $\tau$ decays: powerful probes of non-standard charged current weak interactions

   Pablo Roig🇲🇽

   When looking for heavy ($\mathcal{O}$(few TeV)) New Physics, the most efficient way to benefit from both high and low-energy measurements simultaneously is the use of the Standard Model Effective Field Theory (SMEFT). In this talk I highlight the importance of semileptonic $\tau$ decays in complementing, in this respect, the traditional low-energy precision observables and high-energy measurements. This is yet another reason for considering hadronic tau decays as golden channels at Belle-II beyond the unquestionable interest of the CP violation anomaly in $\tau \to K_S\pi {\nu }_{\tau }$ decays, that I also discuss within the effective theory. A couple of new results for ${\tau }^{-}\to K^{-}{\nu }_{\tau }$ decays are also included.

   hep-phhep-exEPJ Web Conf.(2019)·10 citations
4. 04*

   Confinement from Correlated Instanton-Dyon Ensemble in SU(2) Yang-Mills Theory

   Miguel Angel Lopez-Ruiz🇺🇸 · Yin Jiang🇨🇳 · Jinfeng Liao🇺🇸

   We study the confinement phase transition in $SU(2)$ Yang-Mills theory, based on a statistical ensemble model of correlated instanton-dyons. We show for the first time that such a model provides a quantitative description, in light of the lattice data, for the temperature dependence of the order parameter. We characterize the short-range interaction which plays a crucial role for the properties of such ensemble. The chromo-magnetic charge density as well as the spatial correlations is found to be consistent with known lattice and phenomenological information.

   hep-phnucl-thPRD(2019)·4 citations
5. 05*

   Search for the $t\to ch$ decay at hadron colliders

   M. A. Arroyo-Ureña🇲🇽 · R. Gaitán-Lozano🇲🇽 · E.A. Herrera-Chacón🇲🇽 · J. H. Montes de Oca Y.🇲🇽 · T. A. Valencia-Pérez🇲🇽

   We study the observability for the flavor-changing decay of a top quark $t\to ch$ at the LHC and future hadron colliders, namely, High-Luminosity LHC (HL-LHC), High-Energy LHC (HE-LHC) and Future Circular hadron-hadron Collider (FCC-hh). Two scenarios in which the Higgs boson could decay: into a quark bottom pair $(\text{bb-channel})$ and two photons (\textit{\gamma\gamma-channel}) are analyzed. A Monte Carlo analysis of the signal and the Standard Model (SM) background is computed. Center-of-mass energies of $\sqrt{s}=14,27$\text{and}$100$ TeV and integrated luminosities from $0.3$ to $30$ ab${}^{-1}$ are explored. The theoretical framework adopted in this work is the Type-III Two-Higgs Doublet Model (THDM-III) for which, constraints on the parameter space from the Higgs boson coupling modifiers ${\kappa }_i$ are presented and used in order to evaluate the branching ratio of the $t\to ch$ decay and the ($pp\to t\bar{t},t\to ch$) production cross section. We find that with the integrated luminosity achieved at the LHC, the $t\to ch$ decay is out of the reach of detection. More promising results emerge for the HL-LHC, HE-LHC and FCC-hh in which potential discoveries could be claimed.

   hep-phJHEP(2019)·17 citations
6. 06*

   Gravitational form factors of a spin one particle

   Maxim V. Polyakov🇷🇺 · Bao-Dong Sun🇨🇳

   We define the form factors of the quark and gluon symmetric energy-momentum tensor (EMT). The static EMT is related to the spatial distributions of energy, spin, pressure and shear forces. They are obtained in the form of a multipole expansion. The relations between gravitational form factors and the generalised parton distributions are given.

   hep-phnucl-exnucl-thPRD(2019)·71 citations
7. 07*

   Bound states of relativistic nature

   V.A. Karmanov🇷🇺 · J. Carbonell🇫🇷 · H. Sazdjian🇫🇷

   Bethe-Salpeter equation, for massless exchange and large fine structure constant $\alpha >\pi /4$, in addition to the Balmer series, provides another (abnormal) series of energy levels which are not given by the Schrödinger equation. So strong field can be created by a point-like charge $Z>107$. The nuclei with this charge, though available, they are far from to be point-like that weakens the field. Therefore, the abnormal states of this origin hardly exist. We analyze the more realistic case of exchange by a massive particle when the large value of coupling constant is typical for the strong interaction. It turns out that this interaction still generates a series of abnormal relativistic states. The properties of these solutions are studied. Their existence in nature seems possible.

   hep-phhep-thnucl-th2 citations
8. 08*

   Another walk through the world of chiral dynamics

   Ulf-G. Meißner🇩🇪

   Chiral dynamics is a pretty mature field. Nonetheless, there are many exciting new developments. In this opening talk, I consider S-wave, isospin-zero pion-pion scattering and the calculation of the width of the lightest baryon resonances at two loops. New insights into the chiral dynamics of charm-strange mesons are discussed as well as recent results on the flavor decomposition of the pion-nucleon $\sigma$-term. I end with a short wish-list of lattice QCD tests pertinent to chiral dynamics.

   hep-phhep-latnucl-thPoS(2019)·2 citations
9. 09*

   Enhanced $B\to \mu \bar{\nu }$ Decay at Tree Level as Probe of Extra Yukawa Couplings

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

   With no New Physics seen at the LHC, a second Higgs doublet remains attractive and plausible. The ratio ${\mathcal{R}}_B^{\mu /\tau }=\mathcal{B}(B\to \mu \bar{\nu })/\mathcal{B}(B\to \tau \bar{\nu })$ is predicted at 0.0045 in both the Standard Model and the type II two Higgs doublet model, but it can differ if extra Yukawa couplings exist in Nature, which we deem an experimental issue. Considering recent Belle update on $B\to \mu \bar{\nu }$, we show that in the general two Higgs doublet model, the ratio could be up by a factor of two, which can be probed by the Belle~II experiment with just a few ab${}^{-1}$.

   hep-phhep-exPLB(2020)·24 citations
10. 10*

    Low-momentum pion enhancement from schematic hadronization of a gluon-saturated initial state

    Elizaveta Nazarova🇷🇺 · Łukasz Juchnowski🇵🇱 · David Blaschke🇵🇱 · Tobias Fischer🇵🇱

    We study the particle production in the early stage of the ultrarelativistic heavy-ion collisions. To this end the Boltzmann kinetic equations for gluons and pions with elastic rescattering are considered together with a simple model for the parton-hadron conversion process (hadronisation). It is shown that the overpopulation of the gluon phase space in the initial state leads to an intermediate stage of Bose enhancement in the low-momentum gluon sector which due to the gluon-pion conversion process is then reflected in the final distribution function of pions. This pattern is very similar to the experimental finding of a low-momentum pion enhancement in the ALICE experiment at CERN LHC. Relations to the thermal statistical model of hadron production and the phenomenon of thermal and chemical freeze-out are discussed in this context.

    hep-phnucl-thParticles(2019)·3 citations
11. 11*

    Exact solutions to the sector of the Standard Model Higgs

    Marco Frasca🇮🇹

    Recently, we have found an exact solution to the full set of Dyson-Schwinger equations of the non-interacting part of the Higgs sector of the Standard Model obtained by solving the 1-point correlation function equation. In this work we extend this analysis considering also the other possible solution that is the one experimentally observed in the Standard Model. Indeed, the same set of Dyson-Schwinger equations can be exactly solved for the Standard Model with a constant as a solution for the 1-point correlation function. Differently from the Standard Model solution, the one we have found has a mass spectrum of a Kaluza-Klein particle. This could be a clue toward the identification of a further space dimension. Gap equations are obtained in both cases as also the running self-coupling equations.

    hep-phhep-th0 citations
12. 12*

    Foamy Dark Matter from Monodromies

    Jürgen Berges🇩🇪 · Aleksandr Chatrchyan🇩🇪 · Joerg Jaeckel🇩🇪

    We investigate the dynamics of axion-like particle (ALP) dark matter where the field range is enlarged by a monodromy. The monodromy potential allows sufficient production of dark matter also at larger couplings to the Standard Model particles. The potential typically features a number of "wiggles" that lead to a rapid growth of fluctuations. Using classical-statistical field theory simulations we go beyond the linear regime and treat the system in the non-linear and even non-perturbative regime. For sufficiently strong wiggles the initially homogeneous field is completely converted into fluctuations. The fluctuations correspond to dark matter particles with a non-vanishing velocity and we consider the corresponding restrictions from structure formation as well as the effects on today's dark matter density. Since all the dark matter is made up from these strong fluctuations, the dark matter density features large, $\mathcal{O}(1)$ fluctuations at scales $\lesssim 10^6\mathrm{km}\sqrt{\mathrm{eV}/m_a}$.

    hep-phastro-ph.COJCAP(2019)·54 citations
13. 13*

    Scalar or vector tetraquark state candidate: $Z_c(4100)$

    Zhi-Gang Wang🇨🇳

    In this article, we separate the vector and axialvector components of the tensor diquark operators explicitly, construct the axialvector-axialvector type and vector-vector type scalar tetraquark currents and scalar-tensor type tensor tetraquark current to study the scalar, vector and axialvector tetraquark states with the QCD sum rules in a consistent way. The present calculations do not favor assigning the $Z_c(4100)$ to be a scalar or vector tetraquark state. If the $Z_c(4100)$ is a scalar tetraquark state without mixing effects, it should have a mass about $3.9\mathrm{GeV}$ or $4.0\mathrm{GeV}$ rather than $4.1\mathrm{GeV}$; on the other hand, if the $Z_c(4100)$ is a vector tetraquark state, it should have a mass about $4.2\mathrm{GeV}$ rather than $4.1\mathrm{GeV}$. However, if we introduce mixing, a mixing scalar tetraquark state can have a mass about $4.1\mathrm{GeV}$. As a byproduct, we obtain an axialvector tetraquark candidate for the $Z_c(4020)$.

    hep-phCommun.Theor.Phys.(2019)·9 citations
14. 14*

    Universal behavior of $p$-wave proton-proton fusion near threshold

    Bijaya Acharya🇩🇪 · Lucas Platter🇺🇸 · Gautam Rupak🇺🇸

    We calculate the $p$-wave contribution to the proton-proton fusion $S$ factor and its energy derivative in pionless effective field theory (EFT) up to next-to-leading order. The leading contributions are given by a recoil piece from the Gamow-Teller and Fermi operators, and from relativistic $1/m$ suppressed weak interaction operators. We obtain the value of $(2.5\pm 0.3)\times 10^{-28}\mathrm{MeV}\mathrm{f}{\mathrm{m}}^2$ for the $S$ factor and $(2.2\pm 0.2)\times 10^{-26}\mathrm{f}{\mathrm{m}}^2$ for its energy derivative at threshold. These are smaller than the results of a prior study that employed chiral EFT by several orders of magnitude. We conclude that, contrary to what has been previously reported, the $p$-wave contribution does not need to be considered in a high-precision determination of the $S$ factor at astrophysical energies. Combined with the chiral EFT calculation of Acharya {\it et al.} [Phys. Lett. B \bf{760}, 584 (2016)] for the $s$-wave channel, this gives a total threshold $S$ factor of $S(0)=(4.047_{-0.032}^{+0.024})\times 10^{-23}{\mathrm{MeV}\mathrm{fm}}^2$.

    ↳ nucl-thastro-ph.SRhep-phPRC(2019)·8 citations
15. 15*

    Asymptotic Symmetries and Weinberg's Soft Photon Theorem in Mink${}_{d+2}$

    Temple He🇺🇸 · Prahar Mitra🇺🇸

    We show that Weinberg's leading soft photon theorem in massless abelian gauge theories implies the existence of an infinite-dimensional large gauge symmetry which acts non-trivially on the null boundaries ${\mathcal{I}}^{\pm }$ of $(d+2)$-dimensional Minkowski spacetime. These symmetries are parameterized by an arbitrary function $\epsilon (x)$ of the $d$-dimensional celestial sphere living at ${\mathcal{I}}^{\pm }$. This extends the previously established equivalence between Weinberg's leading soft theorem and asymptotic symmetries from four and higher even dimensions to \emph{all} higher dimensions.

    ↳ hep-thhep-phJHEP(2019)·65 citations
16. 16*

    Axion Dark Matter Detection with CMB Polarization

    Michael A. Fedderke🇺🇸 · Peter W. Graham🇺🇸 · Surjeet Rajendran🇺🇸

    We point out two ways to search for low-mass axion dark matter using cosmic microwave background (CMB) polarization measurements. These appear, in particular, to be some of the most promising ways to directly detect fuzzy dark matter. Axion dark matter causes rotation of the polarization of light passing through it. This gives rise to two novel phenomena in the CMB. First, the late-time oscillations of the axion field today cause the CMB polarization to oscillate in phase across the entire sky. Second, the early-time oscillations of the axion field wash out the polarization produced at last-scattering, reducing the polarized fraction (TE and EE power spectra) compared to the standard prediction. Since the axion field is oscillating, the common (static) `cosmic birefringence' search is not appropriate for axion dark matter. These two phenomena can be used to search for axion dark matter at the lighter end of the mass range, with a reach several orders of magnitude beyond current constraints. We set a limit from the washout effect using existing Planck results, and find significant future discovery potential for CMB detectors searching in particular for the oscillating effect.

    ↳ astro-ph.COhep-phPRD(2019)·216 citations
17. 17*

    Photoproduction of charged final states in ultra-peripheral collisions and electroproduction at an electron-ion collider

    Spencer. R. Klein🇺🇸 · Ya-Ping Xie🇨🇳

    Ultra-peripheral collisions (UPCs) of relativistic ions are an important tool for studying photoproduction at high energies. Vector meson photoproduction is an important tool for nuclear structure measurements and other applications. A future electron-ion collider (EIC) will allow additional studies, using virtual photons with a wide range of $Q^2$. We propose a significant expansion of the UPC and EIC photoproduction physics programs to include charged final states which may be produced via Reggeon exchange. We consider two examples: $a_2^{+}(1320)$, which is a conventional $q\overline{q}$ meson, and the exotic $Z_c^{+}(4430)$ state (modeled here as a tetraquark). The $Z_c^{+}(4430)$ cross-section depends on its internal structure, so photoproduction can test whether the $Z_c^{+}(4430)$ is a tetraquark or other exotic object. We calculate the rates and kinematic distributions for $\gamma p\to X^{+}n$ in $pA$ UPCs and $ep$ collisions at an EIC and in UPCs. The rates are large enough for detailed studies of these final states. Because the cross-section for Reggeon exchange is largest near threshold, the final state rapidity distribution depends on the beam energies. At high-energy colliders like the proposed LHeC or $pA$ collisions at the LHC, the final states are produced at far forward rapidities. For lower energy colliders, the systems are produced closer to mid-rapidity, within reach of central detectors.

    ↳ nucl-thhep-phPRC(2019)·29 citations
18. 18*

    Triangle anomalies and nonrelativistic Nambu-Goldstone modes of generalized global symmetries

    Noriyuki Sogabe🇯🇵 · Naoki Yamamoto🇯🇵

    In massless QCD coupled to QED in an external magnetic field, a photon with the linear polarization in the direction of the external magnetic field mixes with the charge neutral pion through the triangle anomaly, leading to one gapless mode with the quadratic dispersion relation $\omega \sim k^2$ and one gapped mode. We show that this gapless mode can be interpreted as the so-called type-B Nambu-Goldstone (NG) mode associated with the spontaneous breaking of generalized global symmetries and that its presence is solely dictated by the anomalous commutator in the symmetry algebra. We also argue a possible realization of such nonrelativistic NG modes in 3-dimensional Dirac semimetals.

    ↳ hep-thcond-mat.mes-hallhep-phPRD(2019)·22 citations
19. 19*

    Open-Boundary Conditions in the Deconfined Phase

    Adrien Florio🇨🇭 · Olaf Kaczmarek🇩🇪 · Lukas Mazur🇩🇪

    In this work, we consider open-boundary conditions at high temperatures, as they can potentially be of help to measure the topological susceptibility. In particular, we measure the extent of the boundary effects at $T=1.5T_c$ and $T=2.7T_c$. In the first case, it is larger than at $T=0$ while we find it to be smaller in the second case. The length of this "boundary zone" is controlled by the screening masses. We use this fact to measure the scalar and pseudo-scalar screening masses at these two temperatures. We observe a mass gap at $T=1.5T_c$ but not at $T=2.7T_c$. Finally, we use our pseudo-scalar channel analysis to estimate the topological susceptibility. The results at $T=1.5T_c$ are in good agreement with the literature. At $T=2.7T_c$, they appear to suffer from topological freezing, impeding us from providing a precise determination of the topological susceptibility. It still provides us with a lower bound, which is already in mild tension with some of the existing results.

    ↳ hep-lathep-phhep-thEPJC(2019)·11 citations
20. 20*

    Direct Detection of WIMP Dark Matter: Concepts and Status

    Marc Schumann🇩🇪

    The existence of dark matter as evidenced by numerous indirect observations is one of the most important indications that there must be physics beyond the Standard Model of particle physics. This article reviews the concepts of direct detection of dark matter in the form of Weakly Interacting Massive Particles (WIMPs) in ultra-sensitive detectors located in underground laboratories, discusses the expected signatures, detector concepts, and how the stringent low-background requirements are achieved. Finally, it summarizes the current status of the field and provides an outlook on the years to come.

    ↳ astro-ph.COastro-ph.IMhep-phphysics.ins-detJ.Phys.G(2019)·729 citations
21. 21*

    Electron-positron pair production in oscillating electric fields with double-pulse structure

    L. F. Granz🇩🇪 · O. Mathiak🇩🇪 · S. Villalba-Chávez🇩🇪 · C. Müller🇩🇪

    Electron-positron pair production from vacuum in a strong electric field oscillating in time is studied. The field is assumed to consist of two consecutive pulses, with variable time delay in between. Pair production probabilities are obtained by numerical solution of the corresponding time-dependent Dirac equation. Considering symmetric field configurations comprising two identical pulses, we show that the pulse distance strongly affects the momentum spectra of produced particles and even the total production probability. Conversely, in a highly asymmetric situation when the field contains low-intensity prepulse and high-intensity main pulse, we identify a range of field parameters where the prepulse despite its weakness can leave visible traces in the particle spectra.

    ↳ physics.plasm-phhep-phPLB(2019)·23 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.