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Probing the explanation of the muon (g-2) anomaly and thermal light dark matter with the semi-visible dark photon channel
Journal
European Physical Journal C
Date Issued
2021-10-01
Author(s)
Cazzaniga, C.
Odagiu, P.
Depero, E.
Molina Bueno, L.
Andreev, Yu M.
Banerjee, D.
Bernhard, J.
Burtsev, V. E.
Charitonidis, N.
Chumakov, A. G.
Cooke, D.
Crivelli, P.
Dermenev, A. V.
Donskov, S. V.
Dusaev, R. R.
Enik, T.
Feshchenko, A.
Frolov, V. N.
Gardikiotis, A.
Gerassimov, S. G.
Girod, S.
Gninenko, S. N.
Hösgen, M.
Kachanov, V. A.
Karneyeu, A. E.
Kekelidze, G.
Ketzer, B.
Kirpichnikov, D. V.
Kirsanov, M. M.
Kolosov, V. N.
Konorov, I. V.
Kramarenko, V. A.
Kravchuk, L. V.
Krasnikov, N. V.
Lysan, V.
Matveev, V. A.
Mikhailov, Yu V.
Peshekhonov, D. V.
Polyakov, V. A.
Radics, B.
Rojas, R.
Rubbia, A.
Samoylenko, V. D.
Shchukin, D.
Sieber, H.
Tikhomirov, V. O.
Tlisova, I. V.
Tlisov, D. A.
Toropin, A. N.
Trifonov, A. Yu
Vasilishin, B. I.
Arenas, G. Vasquez
Volkov, P. V.
Volkov, V. Yu
Ulloa, P.
Abstract
<jats:title>Abstract</jats:title><jats:p>We report the results of a search for a new vector boson (<jats:inline-formula><jats:alternatives><jats:tex-math>$$ A'$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mml:msup>
<mml:mi>A</mml:mi>
<mml:mo>′</mml:mo>
</mml:msup>
</mml:math></jats:alternatives></jats:inline-formula>) decaying into two dark matter particles <jats:inline-formula><jats:alternatives><jats:tex-math>$$\chi _1 \chi _2$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mml:mrow>
<mml:msub>
<mml:mi>χ</mml:mi>
<mml:mn>1</mml:mn>
</mml:msub>
<mml:msub>
<mml:mi>χ</mml:mi>
<mml:mn>2</mml:mn>
</mml:msub>
</mml:mrow>
</mml:math></jats:alternatives></jats:inline-formula> of different mass. The heavier <jats:inline-formula><jats:alternatives><jats:tex-math>$$\chi _2$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mml:msub>
<mml:mi>χ</mml:mi>
<mml:mn>2</mml:mn>
</mml:msub>
</mml:math></jats:alternatives></jats:inline-formula> particle subsequently decays to <jats:inline-formula><jats:alternatives><jats:tex-math>$$\chi _1$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mml:msub>
<mml:mi>χ</mml:mi>
<mml:mn>1</mml:mn>
</mml:msub>
</mml:math></jats:alternatives></jats:inline-formula> and an off-shell Dark Photon <jats:inline-formula><jats:alternatives><jats:tex-math>$$ A'^* \rightarrow e^+e^-$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mml:mrow>
<mml:msup>
<mml:mi>A</mml:mi>
<mml:mrow>
<mml:mo>′</mml:mo>
<mml:mo>∗</mml:mo>
</mml:mrow>
</mml:msup>
<mml:mo>→</mml:mo>
<mml:msup>
<mml:mi>e</mml:mi>
<mml:mo>+</mml:mo>
</mml:msup>
<mml:msup>
<mml:mi>e</mml:mi>
<mml:mo>-</mml:mo>
</mml:msup>
</mml:mrow>
</mml:math></jats:alternatives></jats:inline-formula>. For a sufficiently large mass splitting, this model can explain in terms of new physics the recently confirmed discrepancy observed in the muon anomalous magnetic moment at Fermilab. Remarkably, it also predicts the observed yield of thermal dark matter relic abundance. A detailed Monte-Carlo simulation was used to determine the signal yield and detection efficiency for this channel in the NA64 setup. The results were obtained re-analyzing the previous NA64 searches for an invisible decay <jats:inline-formula><jats:alternatives><jats:tex-math>$$A'\rightarrow \chi \overline{\chi }$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mml:mrow>
<mml:msup>
<mml:mi>A</mml:mi>
<mml:mo>′</mml:mo>
</mml:msup>
<mml:mo>→</mml:mo>
<mml:mi>χ</mml:mi>
<mml:mover>
<mml:mi>χ</mml:mi>
<mml:mo>¯</mml:mo>
</mml:mover>
</mml:mrow>
</mml:math></jats:alternatives></jats:inline-formula> and axion-like or pseudo-scalar particles <jats:inline-formula><jats:alternatives><jats:tex-math>$$a \rightarrow \gamma \gamma $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mml:mrow>
<mml:mi>a</mml:mi>
<mml:mo>→</mml:mo>
<mml:mi>γ</mml:mi>
<mml:mi>γ</mml:mi>
</mml:mrow>
</mml:math></jats:alternatives></jats:inline-formula>. With this method, we exclude a significant portion of the parameter space justifying the muon g-2 anomaly and being compatible with the observed dark matter relic density for <jats:inline-formula><jats:alternatives><jats:tex-math>$$A'$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mml:msup>
<mml:mi>A</mml:mi>
<mml:mo>′</mml:mo>
</mml:msup>
</mml:math></jats:alternatives></jats:inline-formula> masses from 2<jats:inline-formula><jats:alternatives><jats:tex-math>$$m_e$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mml:msub>
<mml:mi>m</mml:mi>
<mml:mi>e</mml:mi>
</mml:msub>
</mml:math></jats:alternatives></jats:inline-formula> up to 390 MeV and mixing parameter <jats:inline-formula><jats:alternatives><jats:tex-math>$$\varepsilon $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mml:mi>ε</mml:mi>
</mml:math></jats:alternatives></jats:inline-formula> between <jats:inline-formula><jats:alternatives><jats:tex-math>$$3\times 10^{-5}$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mml:mrow>
<mml:mn>3</mml:mn>
<mml:mo>×</mml:mo>
<mml:msup>
<mml:mn>10</mml:mn>
<mml:mrow>
<mml:mo>-</mml:mo>
<mml:mn>5</mml:mn>
</mml:mrow>
</mml:msup>
</mml:mrow>
</mml:math></jats:alternatives></jats:inline-formula> and <jats:inline-formula><jats:alternatives><jats:tex-math>$$2\times 10^{-2}$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mml:mrow>
<mml:mn>2</mml:mn>
<mml:mo>×</mml:mo>
<mml:msup>
<mml:mn>10</mml:mn>
<mml:mrow>
<mml:mo>-</mml:mo>
<mml:mn>2</mml:mn>
</mml:mrow>
</mml:msup>
</mml:mrow>
</mml:math></jats:alternatives></jats:inline-formula>.</jats:p>
<mml:msup>
<mml:mi>A</mml:mi>
<mml:mo>′</mml:mo>
</mml:msup>
</mml:math></jats:alternatives></jats:inline-formula>) decaying into two dark matter particles <jats:inline-formula><jats:alternatives><jats:tex-math>$$\chi _1 \chi _2$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mml:mrow>
<mml:msub>
<mml:mi>χ</mml:mi>
<mml:mn>1</mml:mn>
</mml:msub>
<mml:msub>
<mml:mi>χ</mml:mi>
<mml:mn>2</mml:mn>
</mml:msub>
</mml:mrow>
</mml:math></jats:alternatives></jats:inline-formula> of different mass. The heavier <jats:inline-formula><jats:alternatives><jats:tex-math>$$\chi _2$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mml:msub>
<mml:mi>χ</mml:mi>
<mml:mn>2</mml:mn>
</mml:msub>
</mml:math></jats:alternatives></jats:inline-formula> particle subsequently decays to <jats:inline-formula><jats:alternatives><jats:tex-math>$$\chi _1$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mml:msub>
<mml:mi>χ</mml:mi>
<mml:mn>1</mml:mn>
</mml:msub>
</mml:math></jats:alternatives></jats:inline-formula> and an off-shell Dark Photon <jats:inline-formula><jats:alternatives><jats:tex-math>$$ A'^* \rightarrow e^+e^-$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mml:mrow>
<mml:msup>
<mml:mi>A</mml:mi>
<mml:mrow>
<mml:mo>′</mml:mo>
<mml:mo>∗</mml:mo>
</mml:mrow>
</mml:msup>
<mml:mo>→</mml:mo>
<mml:msup>
<mml:mi>e</mml:mi>
<mml:mo>+</mml:mo>
</mml:msup>
<mml:msup>
<mml:mi>e</mml:mi>
<mml:mo>-</mml:mo>
</mml:msup>
</mml:mrow>
</mml:math></jats:alternatives></jats:inline-formula>. For a sufficiently large mass splitting, this model can explain in terms of new physics the recently confirmed discrepancy observed in the muon anomalous magnetic moment at Fermilab. Remarkably, it also predicts the observed yield of thermal dark matter relic abundance. A detailed Monte-Carlo simulation was used to determine the signal yield and detection efficiency for this channel in the NA64 setup. The results were obtained re-analyzing the previous NA64 searches for an invisible decay <jats:inline-formula><jats:alternatives><jats:tex-math>$$A'\rightarrow \chi \overline{\chi }$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mml:mrow>
<mml:msup>
<mml:mi>A</mml:mi>
<mml:mo>′</mml:mo>
</mml:msup>
<mml:mo>→</mml:mo>
<mml:mi>χ</mml:mi>
<mml:mover>
<mml:mi>χ</mml:mi>
<mml:mo>¯</mml:mo>
</mml:mover>
</mml:mrow>
</mml:math></jats:alternatives></jats:inline-formula> and axion-like or pseudo-scalar particles <jats:inline-formula><jats:alternatives><jats:tex-math>$$a \rightarrow \gamma \gamma $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mml:mrow>
<mml:mi>a</mml:mi>
<mml:mo>→</mml:mo>
<mml:mi>γ</mml:mi>
<mml:mi>γ</mml:mi>
</mml:mrow>
</mml:math></jats:alternatives></jats:inline-formula>. With this method, we exclude a significant portion of the parameter space justifying the muon g-2 anomaly and being compatible with the observed dark matter relic density for <jats:inline-formula><jats:alternatives><jats:tex-math>$$A'$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mml:msup>
<mml:mi>A</mml:mi>
<mml:mo>′</mml:mo>
</mml:msup>
</mml:math></jats:alternatives></jats:inline-formula> masses from 2<jats:inline-formula><jats:alternatives><jats:tex-math>$$m_e$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mml:msub>
<mml:mi>m</mml:mi>
<mml:mi>e</mml:mi>
</mml:msub>
</mml:math></jats:alternatives></jats:inline-formula> up to 390 MeV and mixing parameter <jats:inline-formula><jats:alternatives><jats:tex-math>$$\varepsilon $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mml:mi>ε</mml:mi>
</mml:math></jats:alternatives></jats:inline-formula> between <jats:inline-formula><jats:alternatives><jats:tex-math>$$3\times 10^{-5}$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mml:mrow>
<mml:mn>3</mml:mn>
<mml:mo>×</mml:mo>
<mml:msup>
<mml:mn>10</mml:mn>
<mml:mrow>
<mml:mo>-</mml:mo>
<mml:mn>5</mml:mn>
</mml:mrow>
</mml:msup>
</mml:mrow>
</mml:math></jats:alternatives></jats:inline-formula> and <jats:inline-formula><jats:alternatives><jats:tex-math>$$2\times 10^{-2}$$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mml:mrow>
<mml:mn>2</mml:mn>
<mml:mo>×</mml:mo>
<mml:msup>
<mml:mn>10</mml:mn>
<mml:mrow>
<mml:mo>-</mml:mo>
<mml:mn>2</mml:mn>
</mml:mrow>
</mml:msup>
</mml:mrow>
</mml:math></jats:alternatives></jats:inline-formula>.</jats:p>
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