The ABC Effect and the Occurrence of a Dibaryon Resonance MIN 2016 - PowerPoint PPT Presentation

Fachbereich Physik BLINDBILD The ABC Effect and the Occurrence of a Dibaryon Resonance MIN 2016 Kyoto July 31 – August 2, 2016 Heinz Clement

The�ABC�Effect The�ABC�Effect � … … denotes�a� denotes�a� low low� �mass�enhancement mass�enhancement in�the� in�the� M M ππ � ππ ππ ππ ππ ππ ππ ππ spectrum of� of�nuclear nuclear two two� �pion pion production production spectrum � … … only�shows�up�in�double only�shows�up�in�double� �pionic� pionic� fusion fusion reactions,�if� reactions,�if� � ππ � the�produced� ππ �pair�is� pair�is� isoscalar isoscalar the�produced� � … … is�named�after� is�named�after� A A bashian,� bashian,� B B ooth�and� ooth�and� C C rowe,�who� rowe,�who� � were�the�first�to�observe�this�phenomenon�in�1960 were�the�first�to�observe�this�phenomenon�in�1960 � … … is�now�found�to�be� is�now�found�to�be� strictly�correlated strictly�correlated with�the� with�the� � appearance�of�the� dibaryon�resonance dibaryon�resonance d*(2380) d*(2380) appearance�of�the� ABC Effect and Dibaryon Resonance 2 H. Clement

The�ABC�Gallery�� The�ABC�Gallery�� The�ABC�Gallery�� pd� → 3 He� π 0 π 0 pn� → d� π 0 π 0 dd� → 4 He� π 0 π 0 pn� → d� π 0 π 0 dd� → 4 He� π 0 π 0 @�0.9�GeV @� 1.1� GeV @�1.1�GeV @� 1.1� GeV @�1.1�GeV 25 b/GeV] heavier� 20 µ [ o 15 nuclei�?? π o π /dM 10 σ d 5 0 0.2 0.3 0.4 0.5 0.6 2 M [GeV/c ] π π o o b/GeV] PRL�106�(2011)�202302�����������������PL�B�637�(2006)�223������� PRC�86�(2012)�032201(R) CELSIUS-WASA and WASA-at-COSY measurements ABC Effect and Dibaryon Resonance 3 H. Clement

The�“ “no no� �ABC ABC” ” Gallery�� Gallery�� The� The�“no�ABC” Gallery�� pp� → pp� π 0 π 0 pp� → d� π + π 0 pp� → „ 2 He“ π 0 π 0 pp� → d� π + π 0 pp� → „ 2 He“ π 0 π 0 @�1.3�GeV @� 1.1� GeV @�1.3�GeV @� 1.1� GeV @�1.3�GeV )] b/(GeV)] )] 2 [nb/(MeV/c 800 M 2 M M M b/(GeV/c π 0 π 0 π π 0 0 π π 0 0 π π 0 + 0.4 600 40 µ [ 0 µ π 0 [ π /dM 0 π - 400 0 π π + 0.2 /dM π σ /dM 20 d σ d 200 σ d 0 0 0 0.3 0.4 0.5 300 350 400 450 0.3 0.4 0.5 2 2 M [MeV/c ] M [GeV/c ] M [GeV] π + π π 0 π 0 0 π π 0 0 Phys.Lett. B� 684�(2010)�110 Phys.�Lett.� B 695�(2011)�115 well�described�by�t�channel� ∆∆ ∆∆ process ∆∆ ∆∆ ABC Effect and Dibaryon Resonance 4 H. Clement

What�is�the�reason�for�ABC�effect? What�is�the�reason�for�ABC�effect? � Check�all�observables:�exclusive�and� Check�all�observables:�exclusive�and� � kinematically�complete�measurements measurements kinematically�complete� � Look�on�the�energy�dependence� Look�on�the�energy�dependence�– – in�particular� in�particular� � of�total�cross�section of�total�cross�section ABC Effect and Dibaryon Resonance 5 H. Clement

Isovector :��Total�Cross�Sections :��Total�Cross�Sections Isovector isospin� decomposition ⇒ ⇒ ⇒ ⇒ ∆∆ ∆∆ ∆∆ ∆∆ N*(1440) ∆ (1600)�(?) Phys.�Lett.�B�679�(2009)�30 ABC Effect and Dibaryon Resonance 6 H. Clement

Isovector :��Total�Cross�Sections :��Total�Cross�Sections Isovector isospin� decomposition ⇒ ⇒ ⇒ ⇒ ∆∆ ∆∆ ∆∆ ∆∆ N*(1440) Alvarez�Ruso,�Oset NPA�633�(1998)�519 ∆ (1600)�(?) Phys.�Lett.�B�679�(2009)�30 ABC Effect and Dibaryon Resonance 7 H. Clement

Isoscalar�: … … this�is�what�we�expected! this�is�what�we�expected! Isoscalar�: ABC Effect and Dibaryon Resonance 8 H. Clement

Isoscalar�: … … and�this�is�what�we�found! and�this�is�what�we�found! Isoscalar�: CELSIUS/WASA Phys.Rev.Lett.102, 052301 (2009) ABC Effect and Dibaryon Resonance 9 H. Clement

Isoscalar :�Results�from�WASA�at�COSY :�Results�from�WASA�at�COSY Isoscalar M� ≈ ≈ ≈ 2.37�GeV ≈ m�=�2.37�GeV Γ Γ ≈ Γ Γ ≈ 70�MeV ≈ ≈ “ABC resonance” Γ Γ Γ Γ =����70�MeV Γ Γ intr ∼ Γ Γ ∼ 50 MeV ∼ ∼ Phys.Rev.Lett.106, 242302 (2011) ABC Effect and Dibaryon Resonance 10 H. Clement

* → → → → → d → → ∆∆ → → ∆∆ → ∆∆ ∆∆ ∆∆ → → d → → π 0 π π π 0 π 0 0 0 π 0 π π π 0 0 0 0 0 0 0 0 0 0 pn� → → → → d * → → → ∆∆ ∆∆ ∆∆ → → → d π π π π π π π pn� model p � π � n π � I�(J P )�=�0�(3 + ) ] 4 → π 0 π 0 /c pn d 2 3 [GeV 5 M,� Γ, Γ Γ, Γ Γ, Γ i� ∗ Γ Γ, Γ ∗ Γ ∗ Γ ∗ Γ f� ,�F(q ∆∆ ∆∆ ) M d π ∆∆ ∆∆ π 2 d π 0 0 0 0 M 2 π π 4.5 1 Phys.Rev.Lett.106, 242302 (2011) 4 0 0.1 0.2 0.3 2 2 4 M [GeV /c ] π π M ππ Θ d Θ Θ Θ * ππ ππ ππ ABC�effect ABC Effect and Dibaryon Resonance 11 H. Clement

ππ ππ � ππ ππ ππ ππ ππ ππ �invariant�mass�M invariant�mass�M ππ ππ ππ ππ ππ ππ ππ ππ Phys.Rev.Lett.106, 242302 (2011) “ABC effect” t-channel ∆∆ ∆∆ ∆∆ ∆∆ ABC Effect and Dibaryon Resonance 12 H. Clement

ABC�Effect:� ABC�Effect:� → ∆∆ ∆∆ ∆∆ on�M ∆∆ ∆∆ Mapping�of�d*�→ ∆∆ ∆∆ ∆∆ on�M ππ spectrum Mapping�of�d*� ππ spectrum ππ ππ ππ ππ ππ ππ 2 / (Λ 2 + Γ d* = Γ 0 Λ Λ Λ 2 Λ 2 2 2 / (Λ 2 / (Λ / (Λ / (Λ 2 2 2 + + + q + 2 2 ) 2 2 ) ) ) ) � S S� �wave�decay:�� wave�decay:�� Γ ∆∆ = Γ q ∆∆ ∆∆ Λ Λ Λ Λ 2 2 2 / (Λ / (Λ / (Λ 2 2 2 + + + q ∆∆ 2 2 2 2 ) ) ) 0 q � ∆∆ ∆∆ ∆∆ ∆∆ d*→ → ∆∆ ∆∆ ∆∆ ∆∆ − p = p � q q ∆∆ =�p p ∆ 1 − p ∆ 2 = p N1 +�k k 1 – p p N2 – k k 2 = ∆∆ =� N1 +� 1 – N2 – 2 = � ∆ 1 ∆ 2 =�q q NN +�q q ππ =� NN +� � � ππ � Fusion Fusion :� :�q q NN =�0���� (neglecting�Fermi�motion) NN =�0���� (neglecting�Fermi�motion) � 2 =�q 2 – ⇒ q ⇒ 2� =�M 2 q ∆∆ 2 =�q ππ 2� =�M ππ 2 – 4m 4m π 2 � � ∆∆ ππ ππ π ABC Effect and Dibaryon Resonance 13 H. Clement

Effect�of�Vertex�Function�on�M ππ Spectrum Effect�of�Vertex�Function�on�M ππ Spectrum ππ ππ ππ ππ ππ ππ � Variation�of�cutoff� Variation�of�cutoff� 5 b/GeV] � ∆ ∆ M π 0 π 0 Λ = 0.60 GeV 4 Λ : parameter� Λ : parameter� Λ = 0.30 GeV Λ = 0.20 GeV µ 3 Λ = 0.15 GeV [ best�fit: best�fit: 0 Λ = 0.10 GeV � π � 0 π 2 /M Λ =�0.16�GeV/c Λ =�0.16�GeV/c σ � � d 1 0.2 0.3 0.4 0.5 0.6 M [GeV] π π 0 0 arXiv:1502.07500 ABC Effect and Dibaryon Resonance 14 H. Clement

Effect�of�Vertex�Function�on�M ππ Spectrum Effect�of�Vertex�Function�on�M ππ Spectrum ππ ππ ππ ππ ππ ππ � Variation�of�cutoff� Variation�of�cutoff� 5 b/GeV] � ∆ ∆ M π 0 π 0 Λ = 0.60 GeV 4 Λ : parameter� Λ : parameter� Λ = 0.30 GeV Λ = 0.20 GeV µ 3 Λ = 0.15 GeV [ best�fit: best�fit: 0 Λ = 0.10 GeV � π � 0 π 2 /M Λ =�0.16�GeV/c Λ =�0.16�GeV/c σ � � d 1 0.2 0.3 0.4 0.5 0.6 identical�to� Λ Λ Λ Λ ∆ π !!! !!! !!! !!! M [GeV] ∆ ∆ ∆ →N π π π π π 0 0 arXiv:1502.07500 ABC Effect and Dibaryon Resonance 15 H. Clement

Non� �Fusion�Two Fusion�Two� �Pion�Production:� Pion�Production:� Non π 0 π π π 0 π 0 0 0 π π π 0 π 0 0 0 0 0 0 0 0 0 0 np�→ → np np π π π π π π π np� � No�ABC�effect�! No�ABC�effect�! )] )] M 2 2 � 2 2 [mb/(GeV/c [mb/(GeV/c π π 0 0 1.5 1.5 � Naturally�explained�by�vertex� Naturally�explained�by�vertex� � 1 1 0 0 π π function: 0 0 function: π π /M /M 0.5 0.5 σ σ d d no�fusion ⇒ ⇒ q q NN ≠ 0 0 no�fusion NN ≠ 0.3 0.3 0.4 0.4 0.5 0.5 � � 2 2 M M [GeV/c [GeV/c ] ] π π π π 0 0 0 0 q ∆∆ ≈ q q NN q ∆∆ ≈ � � NN [mb/GeV] [mb/GeV] M 4 4 ⇒ enhancement�in�������� pn ⇒ enhancement�in�������� � � 3 3 pn pn M pn� spectrum M pn� spectrum /dM /dM 2 2 σ σ d d 1 1 PLB�743�(2015)�325 1.9 1.9 2 2 2.1 2.1 arXiv:1502.07500 M M [GeV] [GeV] pn pn ABC Effect and Dibaryon Resonance 16 H. Clement